EFFI Cl ENT CALI BRATI ON AND LI NEARI ZATI ON I N MULTI - ANTENNA SYSTEMS

Field

Various example embodiments relate to efficient calibration and linearization in multi-antenna systems. More specifically, various example embodiments exemplarily relate to measures (including methods, apparatuses and computer program products) for realizing efficient calibration and linearization in multi-antenna systems.

Backaround

The present specification generally relates to multi-antenna systems (beamforming, massive multiple input multiple output (mMIMO), from sub 6 GHz frequency range up to THz frequency range), in particular linearization of the distributed power amplifiers (PA) in order to achieve improved linearity and thus system energy efficiency, and calibration of the individual transmission (Tx) / reception (Rx) paths in order to enable beamforming, beamsteering, and mMIMO operation (e. g. coherent transmission), as well as control thereof.

Here, with respect to linearization, it is noted that modern communication standards use signals of higher modulation order in order to achieve e.g. high throughput. However, this leads to high signal peak-to-average ratios requiring operating the power amplifier with sufficient back-off leading to trade-off energy efficiency by linearity in order to meet the stringent requirements allowed to transmit the signal. Linearization techniques like digital pre-distortion (DPD) enable the power amplifier to operate with improved linearity and efficiency, but to achieve this with highest performance, adaptive linearization needs to be applied, requiring implementation of a feedback path after the PA to acquire the up-converted and amplified signal.

Further, with respect to calibration, it is noted that to make use of spatial multiplexing and further improve data throughput of 5G and future 6G systems, m ulti-antenna systems like beamforming systems, beam steering systems or m MI MO systems employing coherent transm ission are under development. However, to achieve the envisaged performance of such m ultiantenna systems, the systems have to be calibrated for their individual antenna transceiver paths with respect to phase, amplitude, and delay. To achieve this, either calibration user equipments (UE) e.g. in case of over-the- air calibration are required, or in case of system hardware internal calibration, suitable calibration measurement paths and references (e.g. dedicated transceiver (TRX)) need to be implemented.

The feedback paths for linearization and the measurement paths for calibration are independent paths and thus require extra effort and cost.

Furthermore, usually, linearization and calibration need to be done independently, leading to either extra hardware (HW) effort or less frequent linearization (e.g. DPD) and calibration adaptation of increased TRX off time.

Namely, for m ulti-antenna systems, either in fully digital or different variants of hybrid (number of antennas > number of conversion units) , various types of possible calibration specific measurement path implementations are known, such as e.g. daisy chaining, completely internal self-calibration, or over-the-air calibration using external probe antenna.

Figure 6 shows a schematic diagram of an example m ulti-antenna system with linearization and calibration equipment, and in particular illustrates such multi-antenna system with an exemplary transceiver with a DPD (as an example for linearization) feedback path and a separate calibration coupling structure with a calibration path (hardware (HW) internal implementation of a calibration measurement path). Figure 6 thus shows a basic principle implementation concept of the calibration measurement path for a hybrid multi-antenna array with e.g. 16 TRXs and 128 antennas (hybrid m ultiantenna system) . More specifically, the extract shown in Figure 6 illustrates splitting/combining of a conversion TRX to antennas (of which three are shown in Figure 6) .

Here, at least one port of the calibration line implemented in the antenna module is connected to one of the regular transceivers, which can be switched to calibration mode instead of normal operation.

With respect to a feedback path for adaptive linearization (e.g. DPD) , usually, an own full feedback Rx path is implemented (e.g. in case of frequency division duplex (FDD)) ; or at least one of the regular receivers or even up to all receivers are re-used as feedback path during downlink operation in case of time division duplex (TDD) systems. A possible implementation variant of a linearization feedback path is also depicted in Figure 6. Here, the feedback signal at the output of the PA is coupled by a specific coupler device.

That is, as also mentioned beforehand, in such typical approach applying internal hardware implementations of linearization and calibration equipment, the calibration measurement path(s) and the linearization feedback path(s) are at least partially separate paths e.g. partially requiring specific components like couplers, extra radio frequency (RF) lines to be routed, etc.

I n addition, an efficient high signal-to-noise-ratio (SNR) online (in-operation) calibration in such scenarios is not known.

Hence, the problem arises that less specific-hardware requiring approaches for com mon linearization and calibration in multi-antenna systems are needed. Hence, there is a need to provide for efficient calibration and linearization in multi-antenna systems.

Summary

Various example embodiments aim at addressing at least part of the above issues and/or problems and drawbacks.

Various aspects of example embodiments are set out in the appended claims.

According to an exemplary aspect, there is provided an antenna control apparatus, comprising a controller, a plurality of antenna lines connectable to a plurality of respective antennas, each of said antenna lines including a filter circuitry dividing said respective antenna line into an antenna-side antenna line portion and an opposite-side antenna line portion, a com mon coupling line, and a plurality of coupling structures corresponding to said plurality of respective antenna lines, each of said coupling structures being configured to couple a signal on said respective antenna line to said com mon coupling line, wherein each of said coupling structures includes a coupling switch configured such that, in a first coupling switch state, said signal on said respective antenna-side antenna line portion is coupled to said com mon coupling line, in a second coupling switch state, said signal on said respective opposite-side antenna line portion is coupled to said common coupling line, and, in a third coupling switch state, said signal on said respective antenna line is not coupled to said common coupling line, and said controller is configured to control each of said plurality of coupling switches corresponding to said plurality of coupling structures.

According to an exemplary aspect, there is provided a controller of an antenna control apparatus comprising said controller, a plurality of antenna lines connectable to a plurality of respective antennas, each of said antenna lines including a filter circuitry dividing said respective antenna line into an antenna-side antenna line portion and an opposite- side antenna line portion, a common coupling line, and a plurality of coupling structures corresponding to said plurality of respective antenna lines, each of said coupling structures being configured to couple a signal on said respective antenna line to said com mon coupling line, wherein each of said coupling structures includes a coupling switch configured such that, in a first coupling switch state, said signal on said respective antenna-side antenna line portion is coupled to said com mon coupling line, in a second coupling switch state, said signal on said respective opposite-side antenna line portion is coupled to said com mon coupling line, and, in a third coupling switch state, said signal on said respective antenna line is not coupled to said com mon coupling line, wherein said controller is configured to control each of said plurality of coupling switches corresponding to said plurality of coupling structures.

According to an exemplary aspect, there is provided a method of controlling an antenna control apparatus comprising a controller, a plurality of antenna lines connectable to a plurality of respective antennas, each of said antenna lines including a filter circuitry dividing said respective antenna line into an antenna-side antenna line portion and an opposite- side antenna line portion, a common coupling line, and a plurality of coupling structures corresponding to said plurality of respective antenna lines, each of said coupling structures being configured to couple a signal on said respective antenna line to said com mon coupling line, wherein each of said coupling structures includes a coupling switch configured such that, in a first coupling switch state, said signal on said respective antenna-side antenna line portion is coupled to said com mon coupling line, in a second coupling switch state, said signal on said respective opposite-side antenna line portion is coupled to said com mon coupling line, and, in a third coupling switch state, said signal on said respective antenna line is not coupled to said com mon coupling line, the method comprising controlling each of said plurality of coupling switches corresponding to said plurality of coupling structures.

According to an exemplary aspect, there is provided a controller of an antenna control apparatus comprising said controller, a plurality of antenna lines connectable to a plurality of respective antennas, each of said antenna lines including a filter circuitry dividing said respective antenna line into an antenna-side antenna line portion and an opposite- side antenna line portion, a common coupling line, and a plurality of coupling structures corresponding to said plurality of respective antenna lines, each of said coupling structures being configured to couple a signal on said respective antenna line to said com mon coupling line, wherein each of said coupling structures includes a coupling switch configured such that, in a first coupling switch state, said signal on said respective antenna-side antenna line portion is coupled to said com mon coupling line, in a second coupling switch state, said signal on said respective opposite-side antenna line portion is coupled to said com mon coupling line, and, in a third coupling switch state, said signal on said respective antenna line is not coupled to said com mon coupling line, the controller comprising at least one processor, at least one memory including computer program code, and at least one interface configured for com munication with at least another apparatus, the at least one processor, with the at least one memory and the computer program code, being configured to cause the controller to perform controlling each of said plurality of coupling switches corresponding to said plurality of coupling structures.

According to an exemplary aspect, there is provided a computer program product comprising computer-executable computer program code which, when the program is run on a computer (e.g. a computer of an apparatus according to any one of the aforementioned apparatus-related exemplary aspects of the present disclosure), is configured to cause the computer to carry out the method according to any one of the aforementioned method- related exemplary aspects of the present disclosure.

Such computer program product may comprise (or be embodied) a (tangible) computer-readable (storage) medium or the like on which the computerexecutable computer program code is stored, and/or the program may be directly loadable into an internal memory of the computer or a processor thereof. Any one of the above aspects enables an efficient com mon and independent linearization and calibration in m ulti-antenna systems to thereby solve at least part of the problems and drawbacks identified in relation to the prior art.

By way of example embodiments, there is provided efficient calibration and linearization in multi-antenna systems. More specifically, by way of example embodiments, there are provided measures and mechanisms for realizing efficient calibration and linearization in multi-antenna systems.

Thus, improvement is achieved by methods, apparatuses and computer program products enabling/realizing efficient calibration and linearization in multi-antenna systems.

Brief description of the drawings

I n the following, the present disclosure will be described in greater detail by way of non-limiting examples with reference to the accompanying drawings, in which

Figure 1 is a block diagram illustrating a system or apparatus according to example embodiments,

Figure 2 is a block diagram illustrating a system or apparatus according to example embodiments,

Figure 3 is a block diagram illustrating an apparatus according to example embodiments,

Figure 4 is a block diagram illustrating an apparatus according to example embodiments, Figure 5 is a schematic diagram of a procedure according to example embodiments,

Figure 6 shows a schematic diagram of an example m ulti-antenna system with linearization and calibration equipment,

Figure 7 shows a schematic diagram of a m ulti-antenna system with linearization and calibration equipment according to example embodiments,

Figure 8 shows a schematic diagram illustrating linearization and calibration actions according to example embodiments,

Figure 9 shows a schematic diagram of a m ulti-antenna system with linearization and calibration equipment according to example embodiments,

Figure 10 shows a schematic diagram of a multi-antenna system with linearization and calibration equipment according to example embodiments,

Figure 1 1 shows a schematic diagram of a multi-antenna system with linearization and calibration equipment according to example embodiments,

Figure 12 shows a schematic diagram illustrating control of com mon linearization and calibration according to example embodiments,

Figure 13 is a schematic diagram of a procedure according to example embodiments,

Figure 14 is a schematic diagram of a procedure according to example embodiments,

Figure 15 is a schematic diagram of a procedure according to example embodiments, Figure 16 is a schematic diagram of a procedure according to example embodiments,

Figure 17 shows a schematic diagram of a multi-antenna system with linearization and calibration equipment according to example embodiments,

Figure 18 shows a schematic diagram of a multi-antenna system with linearization and calibration equipment according to example embodiments,

Figure 19 shows a schematic diagram of a multi-antenna system with linearization and calibration equipment according to example embodiments,

Figure 20 shows a schematic diagram of a multi-antenna system with linearization and calibration equipment according to example embodiments,

Figure 21 shows a schematic diagram illustrating control of com mon linearization and calibration according to example embodiments,

Figure 22 is a schematic diagram of a procedure according to example embodiments,

Figure 23 is a schematic diagram of a procedure according to example embodiments,

Figure 24 is a schematic diagram of a procedure according to example embodiments, and

Figure 25 is a block diagram alternatively illustrating an apparatus according to example embodiments.

Detailed descriotion The present disclosure is described herein with reference to particular nonlimiting examples and to what are presently considered to be conceivable embodiments. A person skilled in the art will appreciate that the disclosure is by no means limited to these examples, and may be more broadly applied.

It is to be noted that the following description of the present disclosure and its embodiments mainly refers to specifications being used as non-limiting examples for certain exemplary network configurations and deployments. Namely, the present disclosure and its embodiments are mainly described in relation to 3GPP specifications being used as non-lim iting examples for certain exemplary network configurations and deployments. As such, the description of example embodiments given herein specifically refers to term inology which is directly related thereto. Such term inology is only used in the context of the presented non-lim iting examples, and does naturally not limit the disclosure in any way. Rather, any other com munication or com munication related system deployment, etc. may also be utilized as long as compliant with the features described herein.

Hereinafter, various embodiments and implementations of the present disclosure and its aspects or embodiments are described using several variants and/or alternatives. It is generally noted that, according to certain needs and constraints, all of the described variants and/or alternatives may be provided alone or in any conceivable combination (also including combinations of individual features of the various variants and/or alternatives) .

According to example embodiments, in general terms, there are provided measures and mechanisms for (enabling/realizing) efficient calibration and linearization in multi-antenna systems.

As mentioned above, in order to improve PA energy efficiency and thus reduce overall power consumption of multi-antenna systems usually adaptive linearization like DPD is applied, requiring implementation of a feedback path. Furthermore, in order to adequately operate the multi-antenna systems either as beamform ing, beam steering, m Ml MO/ coherent transmission or mixed systems, calibration of the individual antenna TRX paths is absolutely mandatory. To achieve m ulti-antenna system HW internal self-calibration, an adequate calibration measurement path to enable individual phase and amplitude characterization of the respective transm ission (TX) and reception (RX) paths is generally used.

The calibration measurement path and the linearization feedback path are usually at least partially independent paths.

The independent paths and corresponding independent specific structures disadvantageously implicate high size and costs of such equipment.

Hence, in brief, according to example embodiments, a coupling structure with a switch is provided that works as a coupling device from a calibration line to an antenna feeding point / antenna line and vice versa. The calibration line is connected to a common coupling line where the coupling is particularly effected. The switch allows to activate or prevent the coupling to the common coupling line so that signals on the antenna line do no longer couple into the calibration line (e.g. Tx to Calibration/DPD-Rx) , and/or signals on the com mon calibration line do no longer couple to the antenna path (e.g. Calibration-Tx to Rx) .

I n particular, according to example embodiments, a common/combined linearization feedback path and HW internal self-calibration measurement path is provided, which enables to calibrate the individual antenna TX and RX paths as well as allowing to monitor the individual PA output signals, thereby enabling adaptive linearization.

According to example embodiments, such structures and control thereof is provided for, among others, fully digital mMI MO systems, hybrid m ulti- antenna systems (with dedicated PAs per antenna) , and hybrid multi-antenna systems (with several antennas are controlled by a com mon PA) .

Methods/procedures of operating such a common/combined calibration measurement path and linearization feedback path are provided as well.

According to example embodiments, these include methods/procedures of operation to check and calibrate individual antenna paths during regular operation without a need to turn off the system from normal operation for calibration update, which enables improved system performance.

I n other words, according to example embodiments, a possibility to use the tapped signal for both, linearization and calibration simultaneously, and thus, perform linearization and calibration simultaneously, is provided.

However, more generally, according to example embodiments, methods/procedures for adequate controlling of the multi-antenna system and to perform either linearization only, calibration only or sim ultaneous linearization and TX calibration either for a subset of TRX or for full system/all TRX are provided.

Example embodiments are applied to m ulti-antenna systems in general (fully digital, hybrid variants/architectures, from sub 6GHz, m m-wave frequency range up to sub-THz and THz frequency range in case linearization is also applied) .

While example embodiments are described targeting 5G and future 6G distributed or central m ulti-antenna systems, the underlying principle is not limited to such application.

Further, while example embodiments are described for RF frontends in base stations, the underlying principle is not lim ited to such application, but can for example also be applied to mobile equipment (UEs, industry4.0, V2X, etc.) , if m ulti-antenna systems are used.

Example embodiments are specified below in more detail.

Figure 1 is a block diagram illustrating a system or apparatus according to example embodiments, and in particular illustrates an antenna control apparatus according to example embodiments.

Figure 2 is a block diagram illustrating a system or apparatus according to example embodiments, and in particular illustrates an antenna control apparatus according to example embodiments.

I n particular, Figure 2 illustrated a modification of the antenna control apparatus shown in Figure 1 .

As is illustrated in Figure 1 , according to example embodiments, the antenna control apparatus 10, comprises a controller 1 1 , a plurality of antenna lines 12, a common coupling line 14, and a plurality of coupling structures 15a, 15b, 15c, 16 corresponding to said plurality of respective antenna lines 12. The plurality of antenna lines 12 are connectable to a plurality of respective antennas 22 (illustrated in Figure 2), each of said antenna lines 12 including a filter circuitry 13 dividing said respective antenna line 12 into an antennaside antenna line portion 12b and an opposite-side antenna line portion 12a. Each of said coupling structures 15a, 15b, 15c, 16 being configured to couple a signal on said respective antenna line 12 to said com mon coupling line 14. Further, each of said coupling structures 15a, 15b, 15c, 16 includes a coupling switch 16 configured such that, in a first coupling switch state, said signal on said respective antenna-side antenna line portion 12b is coupled to said com mon coupling line 14, in a second coupling switch state, said signal on said respective opposite-side antenna line portion 12a is coupled to said com mon coupling line 14, and, in a third coupling switch state, said signal on said respective antenna line 12 is not coupled to said com mon coupling line 14. Still further, said controller 1 1 is configured to control each of said plurality of coupling switches 16 corresponding to said plurality of coupling structures 15a, 15b, 15c, 16.

Figure 4 is a block diagram illustrating an apparatus according to example embodiments. The apparatus may be a controller 1 1 of an antenna control apparatus. The controller may be the controller 1 1 of the antenna control apparatus of Figures 1 and 2. The controller 1 1 is configured to control each of said plurality of coupling switches 16 corresponding to said plurality of coupling structures 15a, 15b, 15c, 16. Figure 5 is a schematic diagram of a procedure according to example embodiments. The apparatus according to Figure 4 may perform the method of Figure 5 but is not limited to this method. The method of Figure 5 may be performed by the apparatus of Figure 4 but is not lim ited to being performed by this apparatus.

As shown in Figure 5, a procedure according to example embodiments comprises an operation of controlling (S51 ) each of a plurality of coupling switches 16 corresponding to a plurality of coupling structures 15a, 15b, 15c, 16 of an antenna control apparatus 10, the an antenna control apparatus 10 comprising a controller 1 1 , a plurality of antenna lines 12 connectable to a plurality of respective antennas 22, each of said antenna lines 12 including a filter circuitry 13 dividing said respective antenna line 12 into an antennaside antenna line portion 12b and an opposite-side antenna line portion 12a, a common coupling line 14, and said plurality of coupling structures 15a, 15b, 15c, 16 corresponding to said plurality of respective antenna lines 12, each of said coupling structures 15a, 15b, 15c, 16 being configured to couple a signal on said respective antenna line 12 to said common coupling line 14, wherein each of said coupling structures 15a, 15b, 15c, 16 includes a coupling switch 16 configured such that, in a first coupling switch state, said signal on said respective antenna-side antenna line portion 12b is coupled to said com mon coupling line 14, in a second coupling switch state, said signal on said respective opposite-side antenna line portion 12a is coupled to said com mon coupling line 14, and, in a third coupling switch state, said signal on said respective antenna line 12 is not coupled to said com mon coupling line 14.

I n an embodiment at least some of the functionalities of the apparatus shown in Figures 1 , 2, or 4 may be shared between two physically separate devices form ing one operational entity. Therefore, the apparatus may be seen to depict the operational entity comprising one or more physically separate devices for executing at least some of the described processes.

According to further example embodiments, each of said coupling structures 15a, 15b, 15c, 16 being configured to couple a signal on said com mon coupling line 14 to said respective antenna line 12, and said coupling switch 16 of each of said coupling structures 15a, 15b, 15c, 16 is configured such that, in said first coupling switch state, said signal on said com mon coupling line 14 is coupled to said respective antenna-side antenna line portion 12b, and, in said second coupling switch state, said signal on said common coupling line 14 is coupled to said respective opposite-side antenna line portion 12a.

According to further example embodiments, said com mon coupling line 14 is connected to a switching unit 17 (Figure 2) configured to, in a first switching unit state, interconnect said common coupling line 14 with a reception line 18 (Figure 2) connectable to a reception circuit 20 (Figure 2). According to such variation, an exemplary method according to example embodiments may comprise an operation of controlling said switching unit 17. Further, according to such example embodiments, said controller 1 1 may be configured to control said switching unit 17.

According to further example embodiments, said switching unit 17 is configured to, in a second switching unit state, interconnect said com mon coupling line 14 with a transm ission line 19 (Figure 2) connectable to a transm ission circuit 21 . According to further example embodiments, said switching unit 17 is configured to, in a third switching unit state, interconnect one of said plurality of antenna lines 12 with said reception line 18.

According to further example embodiments, said switching unit 17 includes a first switch (e.g. sw1 ) and a second switch (e.g. sw2), said first switch is configured to, in said first switching unit state, interconnect said reception line 18 with a first interconnection line, and said second switch is configured to, in said first switching unit state, interconnect said first interconnection line with said common coupling line 14.

According to further example embodiments, said second switch is configured to, in said second switching unit state, interconnect said transmission line with said common coupling line 14.

According to further example embodiments, said switching unit 17 includes a third switch (e.g. sw3) , said first switch is configured to, in said third switching unit state, interconnect said reception line 18 with a second interconnection line, and said third switch is configured to, in said third switching unit state, interconnect said second interconnection line with said one of said plurality of antenna lines 12.

According to further example embodiments, said switching unit 17 includes a first switch (e.g. sw5) , a second switch (e.g. sw7) , and a third switch (e.g. sw8) , said first switch is configured to, in said first switching unit state, interconnect said reception line 18 with a first interconnection line, said second switch is configured to, in said first switching unit state, interconnect said first interconnection line with a second interconnection line, and said third switch is configured to, in said first switching unit state, interconnect said second interconnection line with said common coupling line 14.

According to further example embodiments, said second switch is configured to, in said second switching unit state, interconnect said transmission line with said second interconnection line, and said third switch is configured to, in said second switching unit state, interconnect said second interconnection line with said com mon coupling line 14.

According to further example embodiments, said switching unit 17 includes a fourth switch (e.g. sw6) and a fifth switch (e.g. sw3) , said first switch is configured to, in said third switching unit state, interconnect said reception line 18 with a third interconnection line, said fourth switch is configured to, in said third switching unit state, interconnect said third interconnection line with a fourth interconnection line, and said fifth switch is configured to, in said third switching unit state, interconnect said fourth interconnection line with said one of said plurality of antenna lines 12.

According to further example embodiments, said antenna control apparatus further comprises said reception circuit 20, said reception line 18 is connected to said reception circuit 20, and said reception circuit 20 includes a calibration unit 31 configured to perform calibration measurement and a linearization unit 32 configured to perform linearization processing. Figure 3 is a block diagram illustrating an apparatus according to example embodiments, and in particular illustrates a reception circuit 20. The reception circuit 20 includes a calibration unit 31 and a linearization unit 32. The reception circuit 20 illustrated in Figure 3 may correspond to the reception circuit 20 shown in Figure 2.

According to a variation of the procedure shown in Figure 5, exemplary additional operations are given, which are inherently independent from each other as such. According to such variation, an exemplary method according to example embodiments may comprise, in a normal transmission and reception operation mode of said plurality of antennas 22, an operation of controlling each of said plurality of coupling switches 16 to assume said third coupling switch state, and an operation of controlling said switching unit 17 to assume said third switching unit state. Further, according to such example embodiments, said controller 1 1 may be configured to, in a normal transmission and reception operation mode of said plurality of antennas 22, control each of said plurality of coupling switches 16 to assume said third coupling switch state, and control said switching unit 17 to assume said third switching unit state.

According to a variation of the procedure shown in Figure 5, exemplary additional operations are given, which are inherently independent from each other as such. According to such variation, an exemplary method according to example embodiments may comprise, in a transmission/transmitter calibration mode of at least one of said plurality of antenna lines 12, an operation of controlling at least one of said plurality of coupling switches 16 corresponding to said at least one of said plurality of antenna lines 12 to assume said first coupling switch state, and an operation of controlling said switching unit 17 to assume said first switching unit state. Further, according to such example embodiments, said controller 1 1 may be configured to, in a transm ission calibration mode of at least one of said plurality of antenna lines 12, control at least one of said plurality of coupling switches 16 corresponding to said at least one of said plurality of antenna lines 12 to assume said first coupling switch state, and control said switching unit 17 to assume said first switching unit state.

According to a variation of the procedure shown in Figure 5, exemplary additional operations are given, which are inherently independent from each other as such. According to such variation, an exemplary method according to example embodiments may comprise, in a reception/receiver calibration mode of at least one of said plurality of antenna lines 12, an operation of controlling at least one of said plurality of coupling switches 16 corresponding to said at least one of said plurality of antenna lines 12 to assume said first coupling switch state, and an operation of controlling said switching unit 17 to assume said second switching unit state. Further, according to such example embodiments, said controller 1 1 may be configured to, in a reception calibration mode of at least one of said plurality of antenna lines 12, control at least one of said plurality of coupling switches 16 corresponding to said at least one of said plurality of antenna lines 12 to assume said first coupling switch state, and control said switching unit 17 to assume said second switching unit state.

According to a variation of the procedure shown in Figure 5, exemplary additional operations are given, which are inherently independent from each other as such. According to such variation, an exemplary method according to example embodiments may comprise, in a linearization mode of at least one of said plurality of antenna lines 12, an operation of controlling at least one of said plurality of coupling switches 16 corresponding to said at least one of said plurality of antenna lines 12 to assume said first coupling switch state or said second coupling switch state, and an operation of controlling said switching unit 17 to assume said first switching unit state. Further, according to such example embodiments, said controller 1 1 may be configured to, in a linearization mode of at least one of said plurality of antenna lines 12, control at least one of said plurality of coupling switches 16 corresponding to said at least one of said plurality of antenna lines 12 to assume said first coupling switch state or said second coupling switch state, and control said switching unit 17 to assume said first switching unit state.

According to further example embodiments, a respective portion of at least two of said plurality of antenna lines 12 is embodied as a com mon antenna line portion, each filter circuitry 13 of said at least two of said plurality of antenna lines 12 is embodied as a com mon filter circuitry, and said com mon filter circuitry is arranged in said com mon antenna line portion.

According to further example embodiments, said antenna control apparatus 10 further comprises said plurality of antennas 22, and said plurality of antenna lines 12 is connected to said plurality of respective antennas 22.

Example embodiments outlined and specified above are explained below in more specific terms. Exemplary embodiments aim at m ulti-antenna systems where both, adaptive linearization, e.g. DPD (in order to improve system efficiency and thus reduce RF frontend power consumption), as well as hardware internal self-calibration is utilized.

As a general principle of example embodiments, coupling to the calibration line is made switchable, and the same path is used for calibration as well as for adaptive pre-distortion.

Heretofore, according to example embodiments, an enhanced common switchable linearization feedback and calibration coupler 11 using a three-pole switch (triple-throw switch, three-position switch) (swC) is applied.

Further, according to example embodiments, a com mon switchable RX/CalTRX/LinFB (receiver/calibration transceiver/linearization feedback) path I 2 is provided, which may comprise at least switches and lines for connection to a receiver and a transm itter (or a transceiver) .

Figure 7 shows a schematic diagram of a m ulti-antenna system with linearization and calibration equipment according to example embodiments, and in particular illustrates an exemplary preferred implementation of a basic com mon linearization (e.g. DPD) feedback and calibration path concept into the analogue RF multi-antenna frontend according to example embodiments. Figure 17 shows a schematic diagram of a multi-antenna system with linearization and calibration equipment according to example embodiments, and in particular illustrates an exemplary alternative implementation of a basic com mon linearization (e.g. DPD) feedback and calibration path concept into the analogue RF multi-antenna frontend according to example embodiments. An exemplary above-mentioned enhanced common switchable linearization feedback and calibration coupler 11 and an exemplary above- mentioned com mon switchable RX/CalTRX/LinFB path I2 are conceivable from Figures 7 and 17. As illustrated in Figure 7, at least one of conventional RX paths is re-used for TDD m ulti-antenna systems for calibration measurement as well as for linearization feedback measurement.

The coupling structure according to example embodiments can be flexibly activated/de-activated and is close to the respective individual antennas. This coupling structure according to example embodiments is achieved by implementation of a calibration switch (swC) as an example of the coupling switch.

This implementation allows to flexibly activate or de-activate coupling of the respective RF signal at the respective antenna into the com mon calibration and linearization feedback line/path I2. Since the switch neither has to handle high power levels nor has to support very high switching speeds, the switch device can be realized as a medium performance and thus low cost device with low control effort.

I n case of an uplink operation, in the implementation according to Figure 7, the RX path is configured for RX operation by adequately setting respective switches (sw1 , sw2) in the com mon RX/CalTRX/LinFB (receiver/calibration transceiver/linearization feedback) path I2 as well as adequately setting TDD switches (sw3) and coupling switches (swC, set to de-activate coupling in order to improve for RX operation the isolation of the com mon RX/CalTRX/LinFB path) at the antennas.

During downlink operation, the com mon RX/CalTRX/LinFB path I2 is configured by adequately setting the switches (sw1 , sw2) for adaptive predistortion and/or calibration measurement. I n this case, according to example embodiments, the following scenarios are possible: a) Perform ing linearization feedback measurement in order to improve PA performance (linearity, energy efficiency) : I n this case, the PA/path to be tapped for signal feedback is activated for signal coupling to the com mon linearization (e.g. DPD) feedback and calibration path by respective activation of the switch (swC) at the respective antenna (with the PA/path to be tapped being selectively tapped either before (a) or after (b) the filter) . The coupled signal, carrying the signal information for the linearization, is fed back to the digital RF unit by adequate configuration of the switches (sw1 , sw2) in the com mon RX/CalTRX/LinFB path and the TDD switch (sw3). Finally, in the digital RF unit, the signal is fed to the linearization (DPD) block. b) Perform ing calibration measurement in order to calibrate the individual TX and RX paths with respect to phase, amplitudes, and delay required for beamforming, beam steering and/or massive MI MO operation : I n this case, the antenna path to be tapped for signal feedback is activated for signal coupling into the com mon linearization (e.g. DPD) feedback and calibration path by respective activation of the switch (swC) at the respective antenna (with the antenna path to be tapped being selectively tapped either before (a) or after (b) the filter) . The coupled signal, carrying the signal information for the calibration (if necessary a calibration specific signal can be applied, e.g. a constant amplitude zero autocorrelation (CAZAC) sequence) is fed back to the digital RF unit by adequate configuration of the switches (sw1 , sw2) in the com mon RX/CalTRX/LinFB path and the TDD control switch (sw3) . Finally, in the digital RF unit, the signal is fed to the calibration and beamform ing block. c) Perform ing linearization and calibration: Under some conditions, an actual user signal (e.g. LTE, NR, e.g. PRS, CSI-RS, etc.) is also usable for calibration. I n such case, by coupling the signal by adequate setting of the respective antenna switch (swC) of the antenna whose signal is to be analyzed (with the antenna path to be tapped being selectively tapped either before (a) or after (b) the filter) and adequate setting of the RX/CalTRX/LinFB path switches (sw1 , sw2) and the TDD switch (sw3) , the tapped signal can be used sim ultaneously for calibration (determ ining respective phase, amplitudes, delays) and linearization. I n this case, the tapped signal is simultaneously fed to the linearization and calibration unit in the digital RF frontend for respective analysis.

I n case of an uplink operation, in the implementation according to Figure 17, the RX path is configured for RX operation by adequately setting respective switches (sw5, sw6, sw7, sw8) in the com mon RX/CalTRX/LinFB (receiver/ calibration transceiver/linearization feedback) path I2 as well as adequately setting TDD switches (sw3) and coupling switches (swC, set to de-activate coupling in order to improve for RX operation the isolation of the com mon RX/CalTRX/LinFB path) at the antennas.

During downlink operation, the com mon RX/CalTRX/LinFB path I2 is configured by adequately setting the switches (sw5, sw6, sw7, sw8) for adaptive pre-distortion and/or calibration measurement. I n this case, according to example embodiments, the following scenarios are possible: a) Perform ing linearization feedback measurement in order to improve PA performance (linearity, energy efficiency) : I n this case, the PA/path to be tapped for signal feedback is activated for signal coupling to the com mon linearization (e.g. DPD) feedback and calibration path by respective activation of the switch (swC) at the respective antenna (with the PA/path to be tapped being selectively tapped either before (a) or after (b) the filter) . The coupled signal, carrying the signal information for the linearization, is fed back to the digital RF unit by adequate configuration of the switches (sw5, sw6, sw7, sw8) in the com mon RX/CalTRX/LinFB path and the TDD switch (sw3) . Finally, in the digital RF unit, the signal is fed to the linearization (DPD) block. b) Perform ing calibration measurement in order to calibrate the individual TX and RX paths with respect to phase, amplitudes, and delay required for beamforming, beam steering and/or massive MI MO operation: I n this case, the antenna path to be tapped for signal feedback is activated for signal coupling into the com mon linearization (e.g. DPD) feedback and calibration path by respective activation of the switch (swC) at the respective antenna (with the antenna path to be tapped being selectively tapped either before (a) or after (b) the filter) . The coupled signal, carrying the signal information for the calibration (if necessary a calibration specific signal can be applied, e.g. a constant amplitude zero autocorrelation (CAZAC) sequence) is fed back to the digital RF unit by adequate configuration of the switches (sw5, sw6, sw7, sw8) in the com mon RX/CalTRX/LinFB path and the TDD control switch (sw3). Finally, in the digital RF unit, the signal is fed to the calibration and beamforming block. c) Perform ing linearization and calibration: Under some conditions, an actual user signal (e.g. LTE, NR, e.g. PRS, CSI-RS, etc.) is also usable for calibration. I n such case, by coupling the signal by adequate setting of the respective antenna switch (swC) of the antenna whose signal is to be analyzed (with the antenna path to be tapped being selectively tapped either before (a) or after (b) the filter) and adequate setting of the RX/CalTRX/LinFB path switches (sw5, sw6, sw7, sw8) and the TDD switch (sw3) , the tapped signal can be used simultaneously for calibration (determining respective phase, amplitudes, delays) and linearization. I n this case, the tapped signal is sim ultaneously fed to the linearization and calibration unit in the digital RF frontend for respective analysis.

As mentioned before and illustrated in Figures 7 and 17, according to example embodiments, the PA/path to be tapped can be selectively tapped either before (a) or after (b) the filter.

If the feedback signal for pre-distortion (i.e., linearization) is tapped after the circulator and filter (b) , in lim ited situations, namely when the signal is directly placed at the suppression edges of the filter (band edges) , it can happen that only a limited bandwidth (BW) and thus only one side of the out- of-band channels can be fed back and analyzed for the linearization. This potential issue does not exist in case of the signal was not directly placed at the band/filter edges, or if, e.g. in future, linearization techniques requiring less BW (e.g. die temperature based) are used, or in case of mm-wave or sub-THz range where large quantities of spectrum is available. On the other hand, when tapping the feedback signal for pre-distortion after the filter (b) , e.g. kind of equalization effects (over frequency) can be achieved as additional benefit.

However in the case that only a lim ited bandwidth is measured and if this constitutes a drawback, the feedback signal for the linearization can alternatively also be tapped before the filter (a) . I n this case, the (bandpass) filter is not in the measured signal path. If gain/attenuation adaptation is required for this operation, low-noise amplifiers (LNA) could e.g. either be bypassed or realized as variable low noise gain amplifiers (both not shown) .

According to example embodiments, during operation, it can be flexibly decided which feedback path signal tapping ((a) or (b)) is currently preferred in the actual operation situation.

According to example embodiments, in view of the implementation of a com mon switchable (activate (a) / activate (b) /de-activate) coupling structure for calibration and linearization together with the configurable RX/CalTRX/LinFB path furthermore supports the following calibration measurements:

- All swC switches are active ((a) or (b)) : This allows for sim ultaneous calibration of all RX paths by sending a calibration signal via the RX/CalTRX/LinFB path to the switchable couplers by which the calibration TX signal couples via the common coupling line to all RX where the respective receive signals of the individual RX paths can be received and analyzed in the digital RF unit. Usually, the system is off from normal operation during this calibration procedure, thus, overall system throughput may be adversely impacted.

Furthermore, by applying orthogonal calibration sequences per TX, also all TX paths can be calibrated simultaneously by activating all swC switches and allowing coupling all the individually applied orthogonal TX signals to the com mon RX/CalTRX/LinFB path. - Some selected swC switches are set to active ((a) or (b)) : Such a setting allows for calibration and/or linearization of selective paths e.g. during normal operation in the field. All selected RX paths can be calibrated and/or linearized simultaneously using RX/CalTRX/LinFB in calibration TX mode. I n case of selected TX path calibration, orthogonal sequences (different sub-carriers or minimum-cross-correlation sequences, etc.) have to be transm itted by the involved TX to be calibrated.

Selective TX and RX calibration and/or linearization measurement of only one selected TX or RX at the same time (selective TX and RX linearization measurement only in case of TX calibration when the power amplifier is active) : This calibration measurement option allows e.g. step-wise calibration of the system during normal operation in the field without major impact on regular operation performance, since only one TX or RX of several tens or hundreds of TRX is calibrated at a point in time and afterwards the respective TRX will be configured for normal operation again, but with updated phase and amplitude corrections.

I n other words, as a significant advantage over known approaches of system TX calibration during normal operation, according to which inherently the calibration signal is transmitted with all antennas into the air (major drawback for calibration during normal operation) , according to example embodiments, it is allowed to select only e.g. one or a few (full system is then calibrated and/or linearized step by step) TX paths for calibration and/or linearization, while the remaining paths are still in normal operation.

This also leads to a high SNR for the online calibration. I n fact, also when applying example embodiments, the TX(s) to be calibrated are transmitting via the respective related antennas into the air. However, since calibration of a very lim ited number of TX at the same time is possible, their respective TX calibration signal power can be reduced during operation or known phases can be applied to take signals corresponding to the calibration signaling out of wanted beams and thus clearly reduce impact of the actually calibrated TXs on the normal operation.

The principles and the arrangement of the switches in a preferred implementation and an alternative implementation as explained above with reference to Figures 7 and 17 and corresponding processes are applicable as well to m ulti-antenna system structures different from those illustrated in Figures 7 and 17, e.g. to m ulti-antenna system structures explained below particularly with reference to Figures 9 ( 18), 10 (19), and 1 1 (20) .

Figure 8 shows a schematic diagram illustrating linearization and calibration actions according to example embodiments, and in particular illustrates potential calibration and linearization actions assigned to system performance impacts.

More specifically, Figure 8 shows in a sum marized manner different possible calibration and linearization actions, assigned to "usually requires the system to be offline and thus impacting overall system performance" or "can be done during normal operation and thus not or only minor impacting system performance".

While known approaches usually require the system to be offline during TRX calibration (upper box), example embodiments implementing com mon switchable coupling structure for calibration and linearization together with the configurable RX/CalTRX/LinFB path, whereby a com mon linearization and calibration path is enabled, linearization and/or calibration of individual or sub-groups of TRX are enabled, and by this, step-by-step full system calibration even during normal operation with no or only minor impact on system performance is enabled (lower box). Even sim ultaneous linearization and TX calibration is enabled by implementation of example embodiments (lower box). Here, it is noted that when "Sim ultaneous all TX Linearization" is performed, swC may be activated to (a) , where linearization (e.g. DPD) FB signal is tapped at the respective PA output, or to (b), where linearization (e.g. DPD) FB signal is tapped at the respective antenna coupler. Further, when "Selective TX Linearization" is performed, swC may be activated to (b) , where full TX path calibration up to respective antenna coupler is performed, or to (a) , where only part of TX path is calibrated (up to PA output) . Further, when "Linearization and Simultaneous Selected TX Calibration" is performed, swC may be activated to (b) , where full TX path calibration up to respective antenna coupler is performed, or to (a), where only part of TX path is calibrated (up to PA output).

Figure 9 shows a schematic diagram of a m ulti-antenna system with linearization and calibration equipment according to example embodiments, and in particular illustrates an exemplary preferred implementation of the basic com mon linearization (e.g. DPD) and calibration path concept (including exemplary above-mentioned enhanced com mon switchable linearization feedback and calibration coupler 11 and an exemplary above-mentioned com mon switchable RX/CalTRX/LinFB path I2) explained above into a fully digital m ulti-antenna system frontend. Figure 18 shows a schematic diagram of a multi-antenna system with linearization and calibration equipment according to example embodiments, and in particular illustrates an exemplary alternative implementation of the basic com mon linearization (e.g. DPD) and calibration path concept (including exemplary above-mentioned enhanced com mon switchable linearization feedback and calibration coupler 11 and an exemplary above-mentioned common switchable RX/CalTRX/LinFB path I2) explained above into a fully digital m ulti-antenna system frontend.

I n the implementation according to Figure 9, sim ilarly to Figure 7, according to example embodiments, by adequately setting respective switches (sw1 , sw2, sw4) in the common RX/CalTRX/LinFB path I2 as well as adequately setting TDD switches (sw3) and coupling switches (swC) , the respective mode of operation (as e.g. indicated by Figure 8) is achieved. I n the implementation according to Figure 18, similarly to Figure 17, according to example embodiments, by adequately setting respective switches (sw4, sw5, sw6, sw7, sw8) in the common RX/CalTRX/LinFB path I2 as well as adequately setting TDD switches (sw3) and coupling switches (swC), the respective mode of operation (as e.g. indicated by Figure 8) is achieved.

Figure 10 shows a schematic diagram of a multi-antenna system with linearization and calibration equipment according to example embodiments, and in particular illustrates an exemplary preferred implementation of the basic com mon linearization (e.g. DPD) and calibration path concept (including exemplary above-mentioned enhanced com mon switchable linearization feedback and calibration coupler 11 and an exemplary above-mentioned com mon switchable RX/CalTRX/LinFB path I 2) explained above into a hybrid multi-antenna system frontend (variant 1 : individual PAs per antenna). Figure 19 shows a schematic diagram of a multi-antenna system with linearization and calibration equipment according to example embodiments, and in particular illustrates an exemplary alternative implementation of the basic com mon linearization (e.g. DPD) and calibration path concept (including exemplary above-mentioned enhanced com mon switchable linearization feedback and calibration coupler 11 and an exemplary above-mentioned com mon switchable RX/CalTRX/LinFB path I 2) explained above into a hybrid multi-antenna system frontend (variant 1 : individual PAs per antenna).

I n the implementation according to Figure 10, sim ilarly to Figure 7, according to example embodiments, by adequately setting respective switches (sw1 , sw2, sw4) in the common RX/CalTRX/LinFB path I2 as well as adequately setting TDD switches (sw3) and coupling switches (swC) , the respective mode of operation (as e.g. indicated by Figure 8) is achieved.

I n the implementation according to Figure 19, similarly to Figure 17, according to example embodiments, by adequately setting respective switches (sw4, sw5, sw6, sw7, sw8) in the common RX/CalTRX/LinFB path I2 as well as adequately setting TDD switches (sw3) and coupling switches (swC), the respective mode of operation (as e.g. indicated by Figure 8) is achieved.

Figure 1 1 shows a schematic diagram of a multi-antenna system with linearization and calibration equipment according to example embodiments, and in particular illustrates an exemplary preferred implementation of basic com mon linearization (e.g. DPD) and calibration path concept (including exemplary above-mentioned enhanced com mon switchable linearization feedback and calibration coupler 11 and an exemplary above-mentioned com mon switchable RX/CalTRX/LinFB path I 2) explained above into a hybrid multi-antenna system frontend (variant 2: com mon PA for several antennas) . Figure 20 shows a schematic diagram of a multi-antenna system with linearization and calibration equipment according to example embodiments, and in particular illustrates an exemplary alternative implementation of basic com mon linearization (e.g. DPD) and calibration path concept (including exemplary above-mentioned enhanced com mon switchable linearization feedback and calibration coupler 11 and an exemplary above-mentioned com mon switchable RX/CalTRX/LinFB path I 2) explained above into a hybrid multi-antenna system frontend (variant 2: com mon PA for several antennas) .

I n the implementation according to Figure 1 1 , sim ilarly to Figure 7, according to example embodiments, by adequately setting respective switches (sw1 , sw2, sw4) in the common RX/CalTRX/LinFB path I2 as well as adequately setting TDD switches (sw3) and coupling switches (swC, swC’), the respective mode of operation (as e.g. indicated by Figure 8) is achieved. The swC’ switches have one port less than the swC switches, since the swC’ switches are not connected to a coupler tapping a PA/path to be tapped before (a) a filter. The swC’ switches are implemented when a com mon PA is used for several antennas and in this case only one path (e.g. the com mon calibration and digital pre-distortion path) has a switch swC coupling the feedback signal at the PA/path to be tapped before (a) the filter. I n the implementation according to Figure 20, similarly to Figure 17, according to example embodiments, by adequately setting respective switches (sw4, sw5, sw6, sw7, sw8) in the common RX/CalTRX/LinFB path I2 as well as adequately setting TDD switches (sw3) and coupling switches (swC, swC’) , the respective mode of operation (as e.g. indicated by Figure 8) is achieved. The swC’ switches have one port less than the swC switches, since the swC’ switches are not connected to a coupler tapping a PA/path to be tapped before (a) a filter. The swC’ switches are implemented when a com mon PA is used for several antennas and in this case only one path (e.g. the common calibration and digital pre-distortion path) has a switch swC coupling the feedback signal at the PA/path to be tapped before (a) the filter.

I n the latter two, i.e., the implementations according to Figures 10 and 1 1 (and the implementations according to Figures 19 and 20) , the beamforming is usually done with passive devices such as phase shifters or delay lines in the analogue domain for the individual antennas/paths.

As illustrated, according to example embodiments, a common RX/CalTRX/LinFB path as well as common switchable linearization feedback and calibration couplers (implementation of switches directly into the coupling configuration at the respective antennas) are utilized. Thereby, reduced frontend complexity, saving of devices (couplers) as well as the possibility to tap individual antenna signals only either for linearization or calibration, even during normal operation can be achieved, while it is allowed to individually activate or de-activate respective coupling, which can contribute to improved system performance (less required off-time for calibration, more frequent monitoring and adaptation of calibration parameters phase, amplitude, and delay).

Figure 12 shows a schematic diagram illustrating control of com mon linearization and calibration according to example embodiments, and in particular illustrates an appropriate management and control concept in relation to the com mon linearization (e.g. DPD) feedback and calibration path approach related to the preferred implementations explained above (with the preferred implementation explained above with reference to Figure 10 as an exemplary concrete control target being shown) . Figure 21 shows a schematic diagram illustrating control of com mon linearization and calibration according to example embodiments, and in particular illustrates an appropriate management and control concept in relation to the common linearization (e.g. DPD) feedback and calibration path approach related to the alternative implementations explained above (with the alternative implementation explained above with reference to Figure 19 as an exemplary concrete control target being shown) .

According to example embodiments, a control, controlling the common linearization (e.g. DPD) and calibration path implementation (including exemplary above-mentioned enhanced com mon switchable linearization feedback and calibration coupler 11 and an exemplary above-mentioned com mon switchable RX/CalTRX/LinFB path I 2) explained above, is preferably implemented in the digital RF frontend with com munication to base band.

According to example embodiments, with respect to the preferred implementations explained above, as shown in Figure 12, the control is configured to control the relevant switches (sw1 , sw2, sw3, sw4, swC, swC) and put them into adequate states for the respective mode of operations (as e.g. indicated by Figure 8) .

According to example embodiments, with respect to the alternative implementations explained above, as shown in Figure 21 , the control is configured to control the relevant switches (sw3, sw4, sw5, sw6, sw7, sw8, swC, swC) and put them into adequate states for the respective mode of operations (as e.g. indicated by Figure 8) .

According to example embodiments, the control is operated as discussed below with reference to Figures 13 to 16 and 22 to 24, respectively illustrating exemplarily global methods/procedures operating a m ulti-antenna system having the common linearization (e.g. DPD) and calibration path implementation (including exemplary above-mentioned enhanced com mon switchable linearization feedback and calibration coupler 11 and an exemplary above-mentioned common switchable RX/CalTRX/LinFB path I 2) explained above.

Figure 13 is a schematic diagram of a procedure according to example embodiments, and in particular illustrates a procedure of a selection of a mode of operation and a normal system operation configuration (Calibration procedure using common calibration/linearization (e.g. DPD) ; selection of operation and regular TRX operation) related to the preferred implementations explained above. Figure 22 is a schematic diagram of a procedure according to example embodiments, and in particular illustrates a procedure of a selection of a mode of operation and a normal system operation configuration (Calibration procedure using com mon calibration/linearization (e.g. DPD) ; selection of operation and regular TRX operation) related to the alternative implementations explained above.

Figure 14 is a schematic diagram of a procedure according to example embodiments, and in particular illustrates a procedure for regular linearization (e.g. DPD) operation and optional sim ultaneous TX calibration (Calibration procedure using com mon calibration/linearization (e.g. DPD) ; regular linearization (e.g. DPD) operation and optional simultaneous TX path calibration) related to the preferred implementations explained above. Figure 23 is a schematic diagram of a procedure according to example embodiments, and in particular illustrates a procedure for regular linearization (e.g. DPD) operation and optional sim ultaneous TX calibration (Calibration procedure using com mon calibration/linearization (e.g. DPD) ; regular linearization (e.g. DPD) operation and optional simultaneous TX path calibration) related to the alternative implementations explained above. Figure 15 is a schematic diagram of a procedure according to example embodiments, and in particular illustrates a procedure for full or partial system calibration (Calibration procedure using common calibration/linearization (e.g. DPD) ; regular calibration operation - full or partial in-operation calibration) related to the preferred implementations explained above. Figure 24 is a schematic diagram of a procedure according to example embodiments, and in particular illustrates a procedure for full or partial system calibration (Calibration procedure using com mon calibration/linearization (e.g. DPD) ; regular calibration operation - full or partial in-operation calibration) related to the alternative implementations explained above.

Figure 16 is a schematic diagram of a procedure according to example embodiments, and in particular illustrates a system operation procedure in case of TRX subset calibration (Calibration procedure using com mon calibration/linearization (e.g. DPD) ; system operation procedure in case of subset (Figure 15) calibration) related to the preferred implementations and the alternative implementations explained above.

I n step S1301 of Figure 13, a kind of system operation is determined.

If the kind of system operation is determ ined to be Linearization (and Calibration) (step S1302 of Figure 13) , the procedure proceeds to step S1303.

I n step S1303 of Figure 13, the procedure of Figure 14 is entered, where after the procedure returns to step S1301 .

If the kind of system operation is determ ined to be Normal TRX Operation (step S1304 of Figure 13) , the procedure proceeds to step S1305. I n step S1305 of Figure 13, all swC (and swC) # n are set/switched to Term ination, and sw1 is set/switched to Rx (connect sw3) , and the procedure proceeds to step S1306.

I n step S1306 of Figure 13, CalLNA is turned off, and the procedure proceeds to step S1307.

I n step S1307, the system is in normal operation, where after the procedure returns to step S1301 .

If the kind of system operation is determ ined to be Calibration (step S1308 of Figure 13) , the procedure proceeds to step S1309.

I n step S1309 of Figure 13, the procedure of Figure 15 (and potentially of Figure 16) is entered, where after the procedure returns to step S1301 .

I n step S2201 of Figure 22, a kind of system operation is determined.

If the kind of system operation is determ ined to be Linearization (and Calibration) (step S2202 of Figure 22) , the procedure proceeds to step S2203.

I n step S2203 of Figure 22, the procedure of Figure 23 is entered, where after the procedure returns to step S2201 .

If the kind of system operation is determ ined to be Normal TRX Operation (step S2204 of Figure 22) , the procedure proceeds to step S2205.

I n step S1305 of Figure 13, all swC (and swC) # n are set/switched to Term ination, switches sw5, sw6 are set to bypass sw7 and sw8 and to connect the opposite-side antenna line portion (circulator) to the down-conversion unit (normal operation, no calibration mode), and sw3 is set/switched to Rx or termination related to the actual operation mode (uplink or downlink) in normal operation, and the procedure proceeds to step S2206.

I n step S2206 of Figure 22, CalLNA is turned off, and the procedure proceeds to step S2207.

I n step S2207, the system is in normal operation, where after the procedure returns to step S2201 .

If the kind of system operation is determ ined to be Calibration (step S2208 of Figure 22) , the procedure proceeds to step S2209.

I n step S2209 of Figure 22, the procedure of Figure 24 (and potentially of Figure 16) is entered, where after the procedure returns to step S2201 .

I n step S1401 of Figure 14, it is determ ined whether linearization (e.g. DPD) is active and commencing. If so, the procedure proceeds to step S1402.

An alternative approach (subordinate approach, as it is causing an interrupt of operation (signal off/on) , thus potentially applied only when putting the system into operation, during maintenance or for m MI MO muted TRX) can be to stop the system signal sending, then the system/frontend configuration (switches, set correct operation mode (TX or RX) , etc.) for the respective operation (linearization and calibration, calibration, ...) is done followed by activating the system sending signal. This could be done in case of e.g. hot- switching would cause an issue/defect to the switches.

I n step S1402 of Figure 14, it is determined whether TRX (# n) enters Tx Phase (e.g. turnaround) . If so, the procedure proceeds to step S1403.

I n step S1403 of Figure 14, swC # n is switched either to PA output coupler (a) or antenna (b) , and the procedure proceeds to step S1404. I n step S1404 of Figure 14, sw4 (if applicable) is set to normal TX operation, sw3 is set to Term ination, sw1 , sw2 are set to connect the coupling line (sw1 connects sw2) to RX (down-converter) , and the procedure proceeds to step S1405.

I n step S1405 of Figure 14, Tx (# n) signal is received and Pre-distortion Coefficient(s) is/are calculated.

Optionally, only if linearization (e.g. DPD) and calibration are to be done simultaneously, the procedure proceeds to step S1406.

Otherwise, the procedure returns to step S1402.

I n step S1406 of Figure 14, Tx (# n) Calibration Coefficients are calculated.

I n the procedure of Figure 14, optionally, serialized Tx linearization (e.g. DPD) is performed.

I n addition, with respect to the procedure of Figure 14, while linearization (e.g. DPD) measurement on a Tx is active, the Calibration of the respective Tx can also be done sim ultaneously.

I n step S2301 of Figure 23, it is determ ined whether linearization (e.g. DPD) is active and commencing. If so, the procedure proceeds to step S2302.

An alternative approach (subordinate approach, as it is causing an interrupt of operation (signal off/on) , thus potentially applied only when putting the system into operation, during maintenance or for m MI MO muted TRX) can be to stop the system signal sending, then the system/frontend configuration (switches, set correct operation mode (TX or RX) , etc.) for the respective operation (linearization and calibration, calibration, ...) is done followed by activating the system sending signal. This could be done in case of e.g. hot- switching would cause an issue/defect to the switches. I n step S2302 of Figure 23, it is determined whether TRX (# n) enters Tx Phase (e.g. turnaround) . If so, the procedure proceeds to step S2303.

I n step S2303 of Figure 14, swC # n is switched either to PA output coupler (a) or antenna (b) , and the procedure proceeds to step S2304.

I n step S2304 of Figure 23, sw4 (if applicable) is set to normal TX operation, sw3 is set to Term ination, sw5 and sw6 are set to connect sw7 and sw8, sw7 is set to connect the RX path, sw8 is set to connect the coupling line, and the procedure proceeds to step S2305.

I n step S2305 of Figure 23, Tx (# n) signal is received and Pre-distortion Coefficient(s) is/are calculated.

Optionally, only if linearization (e.g. DPD) and calibration are to be done simultaneously, the procedure proceeds to step S2306.

Otherwise, the procedure returns to step S2302.

I n step S2306 of Figure 23, Tx (# n) Calibration Coefficients are calculated.

I n the procedure of Figure 23, optionally, serialized Tx linearization (e.g. DPD) is performed.

I n addition, with respect to the procedure of Figure 23, while linearization (e.g. DPD) measurement on a Tx is active, the Calibration of the respective Tx can also be done sim ultaneously.

I n step S1501 of Figure 15, it is determined whether calibration is active and com mencing. If so, the procedure proceeds to steps S1502 and S1507. An alternative approach (subordinate approach, as it is causing an interrupt of operation (signal off/on) , thus potentially applied only when putting the system into operation, during maintenance or for m MI MO muted TRX) can be to stop the system signal sending, then the system/frontend configuration (switches, set correct operation mode (TX or RX) , etc.) for the respective operation (linearization and calibration, calibration, ...) is done followed by activating the system sending signal. This could be done in case of e.g. hot- switching would cause an issue/defect to the switches.

I n step S1502 of Figure 15, it is determ ined whether TRXs enter Tx Period for transm itter (TX) calibration (sw4 (if applicable) is set to normal TX operation). If so, the procedure proceeds to step S1503.

I n step S1507 of Figure 15, it is determined whether TRXs enter Rx Period for receiver (RX) calibration (sw4 (if applicable) is connected to CalTX (to sw2)). If so, the procedure proceeds to step S1508.

With respect to steps S1502 and S1507, it is noted that acyclic operation is possible: If the system is in UL mode, DL Tx could be calibrated without creating interference. Likewise, if the system is in DL mode, instead of transmitting to UEs the system could do Rx calibration.

I n step S1503 of Figure 15, all or a subset (entering procedure of Figure 16 in case of a subset) of swC (swC) are switched to antenna (b) for full path calibration or to (a) to calibrate only a part of TX, and the procedure proceeds to step S1504.

I n step S1504 of Figure 15, sw1 , sw2 are set to connect coupling line (sw1 connected to sw2) to RX (down-converter) , sw3 is set to Term ination, and the procedure proceeds to step S1505.

I n step S1505 of Figure 15, a Calibration Sequence is received (from all/a subset of Tx) via Calibration Rx, and the procedure proceeds to step S1506. I n step S1506 of Figure 15, Tx Calibration Coefficients are calculated.

I n step S1508 of Figure 15, all or a subset (entering procedure of Figure 16 in case of a subset) of swC (swC) are switched to the common coupling line, and the procedure proceeds to step S1509.

I n step S1509 of Figure 15, sw1 is set to connect RX (connect to sw3), sw2, CalLNA Tx are set to connect to the common coupling line, CalLNA is activated, and the procedure proceeds to step S1510.

I n step S1510 of Figure 15, a Calibration Signal is transmitted to Calibration Line, and the procedure proceeds to step S151 1 .

I n step S151 1 of Figure 15, Calibration Sequence is received and RX Calibration Coefficients are calculated.

For Tx calibration, all or only a subset of Tx can be switched to the receiving calibration Rx via calibration line; this can be done in-operation using the regular Tx-signal or using a special Calibration Sequence for just the subset of Txs.

For Rx calibration, all or only a subset of Rx can be switched to the calibration LNA via the calibration line. These Rx will experience a superposition of the regular Rx signal via the antenna and the (stronger) Cali-LNA sequence, possibly in-operation.

I n step S2401 of Figure 24, it is determined whether calibration is active and com mencing. If so, the procedure proceeds to steps S2402 and S2407.

An alternative approach (subordinate approach, as it is causing an interrupt of operation (signal off/on) , thus potentially applied only when putting the system into operation, during maintenance or for m MI MO muted TRX) can be to stop the system signal sending, then the system/frontend configuration (switches, set correct operation mode (TX or RX) , etc.) for the respective operation (linearization and calibration, calibration, ...) is done followed by activating the system sending signal. This could be done in case of e.g. hot- switching would cause an issue/defect to the switches.

I n step S2402 of Figure 24, it is determ ined whether TRXs enter Tx Period for transm itter (TX) calibration (sw4 (if applicable) is set to normal TX operation). If so, the procedure proceeds to step S2403.

I n step S2407 of Figure 24, it is determined whether TRXs enter Rx Period for receiver (RX) calibration (sw4 (if applicable) is set to CalTX (to sw7)) . If so, the procedure proceeds to step S2408.

With respect to steps S2402 and S2407, it is noted that acyclic operation is possible: If the system is in UL mode, DL Tx could be calibrated without creating interference. Likewise, if the system is in DL mode, instead of transmitting to UEs the system could do Rx calibration.

I n step S2403 of Figure 24, all or a subset (entering procedure of Figure 16 in case of a subset) of swC (swC) are switched to antenna (b) for full path calibration or to (a) to calibrate only a part of TX, and the procedure proceeds to step S2404.

I n step S2404 of Figure 24, sw3 is set to Termination, sw5 and sw6 are set to connect sw7 and sw8, sw7 is connected to RX path, sw8 is connected to coupling line, and the procedure proceeds to step S2405.

I n step S2405 of Figure 24, a Calibration Sequence is received (from all/a subset of Tx) via Calibration Rx, and the procedure proceeds to step S2406.

I n step S2406 of Figure 24, Tx Calibration Coefficients are calculated. I n step S2408 of Figure 24, all or a subset (entering procedure of Figure 16 in case of a subset) of swC (swC) are switched to the common coupling line, and the procedure proceeds to step S2409.

I n step S2409 of Figure 24, sw7, sw8, CalLNA Tx are set to connect to com mon coupling line, sw5 and sw6 are set to bypass sw7 and sw8 for RX measurement, CalLNA is activated, and the procedure proceeds to step S2410.

I n step S2410 of Figure 24, a Calibration Signal is transmitted to Calibration Line, and the procedure proceeds to step S241 1 .

I n step S241 1 of Figure 24, Calibration Sequence is received and RX Calibration Coefficients are calculated.

For Tx calibration, all or only a subset of Tx can be switched to the receiving calibration Rx via calibration line; this can be done in-operation using the regular Tx-signal or using a special Calibration Sequence for just the subset of Txs.

For Rx calibration, all or only a subset of Rx can be switched to the calibration LNA via the calibration line. These Rx will experience a superposition of the regular Rx signal via the antenna and the (stronger) Cali-LNA sequence, possibly in-operation.

I n step S1601 of Figure 16, Calibration of a Subset of TX or RX during normal operation is entered from the procedure of Figure 15 or Figure 24 (respectively in case of a subset) , and the procedure proceeds to step S1602.

I n step S1602 of Figure 16, (single or set of) TX(s) or RX(s) to be calibrated is/ are selected, and the procedure proceeds to step S1603. The selection could e.g. be done based on monitoring, where TX(s) or RX(s) with largest changes or TX(s) or RX(s) which have not been re-calibrated since a longer time may have priority. Further criterions could e.g. be that TRX(s) paths which e.g. have been re-activated from MI MO m uting or set to clearly different new power levels may have priority. Other criterions for selection are also possible.

I n step S1603 of Figure 16, concerned TX(s) or RX(s) to be calibrated are set to be not considered for beamforming during respective calibration phase, and the procedure proceeds to step S1604.

I n step S1604 of Figure 16, normal system operation with adapted beamforming weights without TX(s) or RX(s) to be calibrated is performed, and the procedure proceeds to step S1605.

I n step S1605 of Figure 16, selected TX(s) or RX(s) are calibrated and a new calibration set is created, and the procedure proceeds to step S1606.

I n step S1606 of Figure 16, beamform ing is updated considering new calibration sets of calibrated TX(s) and RX(s) , and the procedure proceeds to step S1607.

I n step S1607 of Figure 16, calibrated TX(s) and RX(s) are set to normal operation, and the procedure proceeds to step S1608.

I n step S1608 of Figure 16, a reiteration (returning to step S1601 ) is done in case of new TX(s) or RX(s) subset is to be calibrated. Otherwise, normal operation of full system is performed.

For Tx calibration, all or only a subset of Tx can be switched to the receiving calibration Rx via calibration line; this can be done in-operation using the regular Tx-signal or using a special Calibration Sequence for just the subset of Txs. For Rx calibration, all or only a subset of Rx can be switched to the calibration LNA via the calibration line. These Rx will experience a superposition of the regular Rx signal via the antenna and the (stronger) Cali-LNA sequence, possibly in-operation.

Concluding, example embodiments show implementation of a calibration switch arrangement which enables new advanced features like sim ultaneous linearization and calibration or calibration of sub-groups of TRX even during normal operation, which can clearly improve performance of the system since system off-time for calibration during normal operation can be avoided. As an example, during low load times, when not all TRX are needed to serve a lower number of users, sub-groups of TRX can be easily defined and calibrated during operation by the disclosed calibration network implementation.

Furthermore, example embodiments show control functions and blocks for the disclosed calibration network implementation as shown in Figure 12 (and Figure 21 ) as well as the related procedures to operate such a system and to perform different functions like com mon linearization and calibration, or calibration of TRX sub-groups only or calibration of a full system .

As indicated in Figure 16, TRX can be selected for sub-group calibration during normal operation e.g. based on duration since last calibration, or in case of operation conditions have been changed for specific TRX (like e.g. change of load, PA supply voltage adaptation, selective linearization (e.g. DPD) has been done, have been activated from MI MO muting, etc.) .

Example embodiments can be applied to different m ulti-antenna architectures, such as e.g. fully digital or hybrid systems, operating e.g. in frequency ranges of sub-6 GHz to m m-wave range, THz frequency range, etc. Compared to implementation of individual linearization feedback path and calibration measurement path, advantageously, the com mon/combined linearization feedback path and calibration measurement paths and the related methods of control and operation thereof as provided herein allow for calibration during operation, as well as reduced complexity and cost (e.g. saving of couplers for linearization feedback path, less RF lines) .

According to example embodiments, reduced frontend complexity, saving of devices (couplers) as well as the possibility to tap individual antenna signals only either for linearization or calibration, even during normal operation, can be achieved. It is allowed to individually activate or de-activate respective coupling, which can contribute to improved system performance (less required off-time for calibration, more frequent monitoring and adaptation of calibration parameters phase, amplitude, and delay) .

The above-described procedures and functions may be implemented by respective functional elements, processors, or the like, as described below.

I n the foregoing exemplary description of the network entity, only the units that are relevant for understanding the principles of the disclosure have been described using functional blocks. The network entity may comprise further units that are necessary for its respective operation. However, a description of these units is om itted in this specification. The arrangement of the functional blocks of the devices is not construed to limit the disclosure, and the functions may be performed by one block or further split into sub-blocks.

When in the foregoing description it is stated that the apparatus, i.e. network entity (or some other means) is configured to perform some function, this is to be construed to be equivalent to a description stating that a (i.e. at least one) processor or corresponding circuitry, potentially in cooperation with computer program code stored in the memory of the respective apparatus, is configured to cause the apparatus to perform at least the thus mentioned function. Also, such function is to be construed to be equivalently implementable by specifically configured circuitry or means for performing the respective function (i.e. the expression “unit configured to" is construed to be equivalent to an expression such as “means for”).

I n Figure 25, an alternative illustration of apparatuses according to example embodiments is depicted. As indicated in Figure 25, according to example embodiments, the apparatus (controller) 1 1 ’ (corresponding to the controller 1 1 ) comprises a processor 251 , a memory 252 and an interface 253, which are connected by a bus 254 or the like. The apparatuses may be connected via link 255 e.g. to other apparatuses.

The processor 251 and/or the interface 253 may also include a modem or the like to facilitate comm unication over a (hardwire or wireless) link, respectively. The interface 253 may include a suitable transceiver coupled to one or more antennas or com munication means for (hardwire or wireless) com munications with the linked or connected device(s), respectively. The interface 253 is generally configured to comm unicate with at least one other apparatus, i.e. the interface thereof.

The memory 252 may store respective programs assumed to include program instructions or computer program code that, when executed by the respective processor, enables the respective electronic device or apparatus to operate in accordance with the example embodiments.

I n general terms, the respective devices/ apparatuses (and/or parts thereof) may represent means for perform ing respective operations and/or exhibiting respective functionalities, and/or the respective devices (and/or parts thereof) may have functions for performing respective operations and/or exhibiting respective functionalities.

When in the subsequent description it is stated that the processor (or some other means) is configured to perform some function, this is to be construed to be equivalent to a description stating that at least one processor, potentially in cooperation with computer program code stored in the memory of the respective apparatus, is configured to cause the apparatus to perform at least the thus mentioned function. Also, such function is to be construed to be equivalently implementable by specifically configured means for perform ing the respective function (i.e. the expression “processor configured to [cause the apparatus to] perform xxx-ing” is construed to be equivalent to an expression such as “means for xxx-ing”) .

According to example embodiments, an apparatus representing the controller 1 1 comprises at least one processor 251 , at least one memory 252 including computer program code, and at least one interface 253 configured for com munication with at least another apparatus. The processor (i.e. the at least one processor 251 , with the at least one memory 252 and the computer program code) is configured to perform controlling each of a plurality of coupling switches corresponding to a plurality of coupling structures (thus the apparatus comprising corresponding means for controlling).

For further details regarding the operability/functionality of the individual apparatuses, reference is made to the above description in connection with any one of Figures 1 to 16, respectively.

For the purpose of the present disclosure as described herein above, it should be noted that

- method steps likely to be implemented as software code portions and being run using a processor at a network server or network entity (as examples of devices, apparatuses and/or modules thereof, or as examples of entities including apparatuses and/or modules therefore) , are software code independent and can be specified using any known or future developed program ming language as long as the functionality defined by the method steps is preserved;

- generally, any method step is suitable to be implemented as software or by hardware without changing the idea of the embodiments and its modification in terms of the functionality implemented; - method steps and/or devices, units or means likely to be implemented as hardware components at the above-defined apparatuses, or any module(s) thereof, (e.g., devices carrying out the functions of the apparatuses according to the embodiments as described above) are hardware independent and can be implemented using any known or future developed hardware technology or any hybrids of these, such as MOS (Metal Oxide Sem iconductor) , CMOS (Complementary MOS) , BiMOS (Bipolar MOS) , BiCMOS (Bipolar CMOS) , ECL (Em itter Coupled Logic) , TTL (Transistor-Transistor Logic) , etc., using for example ASI C (Application Specific IC (I ntegrated Circuit)) components, FPGA (Field-program mable Gate Arrays) components, CPLD (Complex Program mable Logic Device) components or DSP (Digital Signal Processor) components;

- devices, units or means (e.g. the above-defined network entity or network register, or any one of their respective units/means) can be implemented as individual devices, units or means, but this does not exclude that they are implemented in a distributed fashion throughout the system , as long as the functionality of the device, unit or means is preserved;

- an apparatus like the user equipment and the network entity /network register may be represented by a semiconductor chip, a chipset, or a (hardware) module comprising such chip or chipset; this, however, does not exclude the possibility that a functionality of an apparatus or module, instead of being hardware implemented, be implemented as software in a (software) module such as a computer program or a computer program product comprising executable software code portions for execution/being run on a processor;

- a device may be regarded as an apparatus or as an assembly of more than one apparatus, whether functionally in cooperation with each other or functionally independently of each other but in a same device housing, for example.

I n general, it is to be noted that respective functional blocks or elements according to above-described aspects can be implemented by any known means, either in hardware and/or software, respectively, if it is only adapted to perform the described functions of the respective parts. The mentioned method steps can be realized in individual functional blocks or by individual devices, or one or more of the method steps can be realized in a single functional block or by a single device.

Generally, any method step is suitable to be implemented as software or by hardware without changing the idea of the present disclosure. Devices and means can be implemented as individual devices, but this does not exclude that they are implemented in a distributed fashion throughout the system , as long as the functionality of the device is preserved. Such and similar principles are to be considered as known to a skilled person.

Software in the sense of the present description comprises software code as such comprising code means or portions or a computer program or a computer program product for performing the respective functions, as well as software (or a computer program or a computer program product) embodied on a tangible medium such as a computer-readable (storage) medium having stored thereon a respective data structure or code means/portions or embodied in a signal or in a chip, potentially during processing thereof.

The present disclosure also covers any conceivable combination of method steps and operations described above, and any conceivable combination of nodes, apparatuses, modules or elements described above, as long as the above-described concepts of methodology and structural arrangement are applicable.

I n view of the above, there are provided measures for efficient calibration and linearization in m ulti-antenna systems. Such measures exemplarily comprise a controller of an antenna control apparatus comprising said controller, a plurality of antenna lines connectable to a plurality of respective antennas, each of said antenna lines including a filter circuitry dividing said respective antenna line into an antenna-side antenna line portion and an opposite-side antenna line portion, a com mon coupling line, and a plurality of coupling structures corresponding to said plurality of respective antenna lines, each of said coupling structures being configured to couple a signal on said respective antenna line to said com mon coupling line, wherein each of said coupling structures includes a coupling switch configured such that, in a first coupling switch state, said signal on said respective antenna-side antenna line portion is coupled to said com mon coupling line, in a second coupling switch state, said signal on said respective opposite-side antenna line portion is coupled to said com mon coupling line, and, in a third coupling switch state, said signal on said respective antenna line is not coupled to said com mon coupling line, wherein said controller is configured to control each of said plurality of coupling switches corresponding to said plurality of coupling structures.

Even though the disclosure is described above with reference to the examples according to the accompanying drawings, it is to be understood that the disclosure is not restricted thereto. Rather, it is apparent to those skilled in the art that the present disclosure can be modified in many ways without departing from the scope of the inventive idea as disclosed herein.

Among others, following example Items are covered by the above-disclosed details.

Item 1 . An antenna control apparatus, comprising a controller, a plurality of antenna lines connectable to a plurality of respective antennas, each of said antenna lines including a filter circuitry dividing said respective antenna line into an antenna-side antenna line portion and an opposite- side antenna line portion, a com mon coupling line, and a plurality of coupling structures corresponding to said plurality of respective antenna lines, each of said coupling structures being configured to couple a signal on said respective antenna line to said com mon coupling line, wherein each of said coupling structures includes a coupling switch configured such that, in a first coupling switch state, said signal on said respective antenna-side antenna line portion is coupled to said common coupling line, in a second coupling switch state, said signal on said respective opposite-side antenna line portion is coupled to said common coupling line, and, in a third coupling switch state, said signal on said respective antenna line is not coupled to said common coupling line, and said controller is configured to control each of said plurality of coupling switches corresponding to said plurality of coupling structures.

Item 2. The antenna control apparatus according to Item 1 , wherein each of said coupling structures being configured to couple a signal on said common coupling line to said respective antenna line, and said coupling switch of each of said coupling structures is configured such that, in said first coupling switch state, said signal on said com mon coupling line is coupled to said respective antenna-side antenna line portion, and, in said second coupling switch state, said signal on said common coupling line is coupled to said respective opposite-side antenna line portion.

Item 3. The antenna control apparatus according to Item 1 or 2, wherein said com mon coupling line is connected to a switching unit configured to, in a first switching unit state, interconnect said common coupling line with a reception line connectable to a reception circuit, and said controller is configured to control said switching unit.

Item 4. The antenna control apparatus according to Item 3, wherein said switching unit is configured to, in a second switching unit state, interconnect said com mon coupling line with a transm ission line connectable to a transm ission circuit.

Item 5. The antenna control apparatus according to Item 3 or 4, wherein said switching unit is configured to, in a third switching unit state, interconnect one of said plurality of antenna lines with said reception line.

Item 6. The antenna control apparatus according to any of Items 3 to 5, wherein said switching unit includes a first switch and a second switch, said first switch is configured to, in said first switching unit state, interconnect said reception line with a first interconnection line, and said second switch is configured to, in said first switching unit state, interconnect said first interconnection line with said common coupling line.

Item 7. The antenna control apparatus according to Item 6, wherein said second switch is configured to, in said second switching unit state, interconnect said transmission line with said com mon coupling line.

Item 8. The antenna control apparatus according to Item 6 or 7, wherein said switching unit includes a third switch, said first switch is configured to, in said third switching unit state, interconnect said reception line with a second interconnection line, and said third switch is configured to, in said third switching unit state, interconnect said second interconnection line with said one of said plurality of antenna lines.

Item 9. The antenna control apparatus according to any of Items 3 to 5, wherein said switching unit includes a first switch, a second switch, and a third switch, said first switch is configured to, in said first switching unit state, interconnect said reception line with a first interconnection line, said second switch is configured to, in said first switching unit state, interconnect said first interconnection line with a second interconnection line, and said third switch is configured to, in said first switching unit state, interconnect said second interconnection line with said com mon coupling line.

Item 10. The antenna control apparatus according to Item 9, wherein said second switch is configured to, in said second switching unit state, interconnect said transmission line with said second interconnection line, and said third switch is configured to, in said second switching unit state, interconnect said second interconnection line with said com mon coupling line.

Item 1 1 . The antenna control apparatus according to Item 9 or 10, wherein said switching unit includes a fourth switch and a fifth switch, said first switch is configured to, in said third switching unit state, interconnect said reception line with a third interconnection line, said fourth switch is configured to, in said third switching unit state, interconnect said third interconnection line with a fourth interconnection line, and said fifth switch is configured to, in said third switching unit state, interconnect said fourth interconnection line with said one of said plurality of antenna lines.

Item 12. The antenna control apparatus according to any of Items 3 to 1 1 , further comprising said reception circuit, wherein said reception line is connected to said reception circuit, and said reception circuit includes a calibration unit configured to perform calibration measurement and a linearization unit configured to perform linearization processing.

Item 13. The antenna control apparatus according to any of Items 5 to 12, wherein said controller is configured to, in a normal transm ission and reception operation mode of said plurality of antennas, control each of said plurality of coupling switches to assume said third coupling switch state, and control said switching unit to assume said third switching unit state.

Item 14. The antenna control apparatus according to any of Items 5 to 13, wherein said controller is configured to, in a transm ission calibration mode of at least one of said plurality of antenna lines, control at least one of said plurality of coupling switches corresponding to said at least one of said plurality of antenna lines to assume said first coupling switch state, and control said switching unit to assume said first switching unit state.

Item 15. The antenna control apparatus according to any of Items 5 to 14, wherein said controller is configured to, in a reception calibration mode of at least one of said plurality of antenna lines, control at least one of said plurality of coupling switches corresponding to said at least one of said plurality of antenna lines to assume said first coupling switch state, and control said switching unit to assume said second switching unit state.

Item 16. The antenna control apparatus according to any of Items 5 to 15, wherein said controller is configured to, in a linearization mode of at least one of said plurality of antenna lines, control at least one of said plurality of coupling switches corresponding to said at least one of said plurality of antenna lines to assume said first coupling switch state or said second coupling switch state, and control said switching unit to assume said first switching unit state.

Item 17. The antenna control apparatus according to any of Items 1 to 16, wherein a respective portion of at least two of said plurality of antenna lines is embodied as a common antenna line portion, each filter circuitry of said at least two of said plurality of antenna lines is embodied as a com mon filter circuitry, and said common filter circuitry is arranged in said common antenna line portion.

Item 18. The antenna control apparatus according to any of Items 1 to 17, further comprising said plurality of antennas, wherein said plurality of antenna lines is connected to said plurality of respective antennas.

Item 19. A controller of an antenna control apparatus comprising said controller, a plurality of antenna lines connectable to a plurality of respective antennas, each of said antenna lines including a filter circuitry dividing said respective antenna line into an antenna-side antenna line portion and an opposite-side antenna line portion, a com mon coupling line, and a plurality of coupling structures corresponding to said plurality of respective antenna lines, each of said coupling structures being configured to couple a signal on said respective antenna line to said com mon coupling line, wherein each of said coupling structures includes a coupling switch configured such that, in a first coupling switch state, said signal on said respective antenna-side antenna line portion is coupled to said com mon coupling line, in a second coupling switch state, said signal on said respective opposite-side antenna line portion is coupled to said com mon coupling line, and, in a third coupling switch state, said signal on said respective antenna line is not coupled to said com mon coupling line, wherein said controller is configured to control each of said plurality of coupling switches corresponding to said plurality of coupling structures.

Item 20. The controller according to Item 19, wherein each of said coupling structures being configured to couple a signal on said common coupling line to said respective antenna line, and said coupling switch of each of said coupling structures is configured such that, in said first coupling switch state, said signal on said com mon coupling line is coupled to said respective antenna-side antenna line portion, and, in said second coupling switch state, said signal on said common coupling line is coupled to said respective opposite-side antenna line portion.

Item 21 . The controller according to Item 19 or 20, wherein said com mon coupling line is connected to a switching unit configured to, in a first switching unit state, interconnect said common coupling line with a reception line connectable to a reception circuit, and said controller is configured to control said switching unit.

Item 22. The controller according to Item 21 , wherein said switching unit is configured to, in a second switching unit state, interconnect said com mon coupling line with a transm ission line connectable to a transm ission circuit.

Item 23. The controller according to Item 21 or 22, wherein said switching unit is configured to, in a third switching unit state, interconnect one of said plurality of antenna lines with said reception line.

Item 24. The controller according to any of Items 21 to 23, wherein said switching unit includes a first switch and a second switch, said first switch is configured to, in said first switching unit state, interconnect said reception line with a first interconnection line, and said second switch is configured to, in said first switching unit state, interconnect said first interconnection line with said common coupling line. Item 25. The controller according to Item 24, wherein said second switch is configured to, in said second switching unit state, interconnect said transmission line with said com mon coupling line.

Item 26. The controller according to Item 24 or 25, wherein said switching unit includes a third switch, said first switch is configured to, in said third switching unit state, interconnect said reception line with a second interconnection line, and said third switch is configured to, in said third switching unit state, interconnect said second interconnection line with said one of said plurality of antenna lines.

Item 27. The controller according to any of Items 21 to 23, wherein said switching unit includes a first switch, a second switch, and a third switch, said first switch is configured to, in said first switching unit state, interconnect said reception line with a first interconnection line, said second switch is configured to, in said first switching unit state, interconnect said first interconnection line with a second interconnection line, and said third switch is configured to, in said first switching unit state, interconnect said second interconnection line with said com mon coupling line.

Item 28. The controller according to Item 27, wherein said second switch is configured to, in said second switching unit state, interconnect said transmission line with said second interconnection line, and said third switch is configured to, in said second switching unit state, interconnect said second interconnection line with said com mon coupling line.

Item 29. The controller according to Item 27 or 28, wherein said switching unit includes a fourth switch and a fifth switch, said first switch is configured to, in said third switching unit state, interconnect said reception line with a third interconnection line, said fourth switch is configured to, in said third switching unit state, interconnect said third interconnection line with a fourth interconnection line, and said fifth switch is configured to, in said third switching unit state, interconnect said fourth interconnection line with said one of said plurality of antenna lines.

Item 30. The controller according to any of Items 21 to 29, wherein said antenna control apparatus further comprises said reception circuit, said reception line is connected to said reception circuit, and said reception circuit includes a calibration unit configured to perform calibration measurement and a linearization unit configured to perform linearization processing.

Item 31 . The controller according to any of Items 23 to 30, wherein said controller is configured to, in a normal transm ission and reception operation mode of said plurality of antennas, control each of said plurality of coupling switches to assume said third coupling switch state, and control said switching unit to assume said third switching unit state.

Item 32. The controller according to any of Items 23 to 31 , wherein said controller is configured to, in a transm ission calibration mode of at least one of said plurality of antenna lines, control at least one of said plurality of coupling switches corresponding to said at least one of said plurality of antenna lines to assume said first coupling switch state, and control said switching unit to assume said first switching unit state. Item 33. The controller according to any of Items 23 to 32, wherein said controller is configured to, in a reception calibration mode of at least one of said plurality of antenna lines, control at least one of said plurality of coupling switches corresponding to said at least one of said plurality of antenna lines to assume said first coupling switch state, and control said switching unit to assume said second switching unit state.

Item 34. The controller according to any of Items 23 to 33, wherein said controller is configured to, in a linearization mode of at least one of said plurality of antenna lines, control at least one of said plurality of coupling switches corresponding to said at least one of said plurality of antenna lines to assume said first coupling switch state or said second coupling switch state, and control said switching unit to assume said first switching unit state.

Item 35. The controller according to any of Items 19 to 34, wherein a respective portion of at least two of said plurality of antenna lines is embodied as a common antenna line portion, each filter circuitry of said at least two of said plurality of antenna lines is embodied as a com mon filter circuitry, and said common filter circuitry is arranged in said common antenna line portion.

Item 36. The controller according to any of Items 19 to 35, wherein said antenna control apparatus further comprises said plurality of antennas, and said plurality of antenna lines is connected to said plurality of respective antennas. Item 37. A method of controlling an antenna control apparatus comprising a controller, a plurality of antenna lines connectable to a plurality of respective antennas, each of said antenna lines including a filter circuitry dividing said respective antenna line into an antenna-side antenna line portion and an opposite-side antenna line portion, a com mon coupling line, and a plurality of coupling structures corresponding to said plurality of respective antenna lines, each of said coupling structures being configured to couple a signal on said respective antenna line to said com mon coupling line, wherein each of said coupling structures includes a coupling switch configured such that, in a first coupling switch state, said signal on said respective antenna-side antenna line portion is coupled to said com mon coupling line, in a second coupling switch state, said signal on said respective opposite-side antenna line portion is coupled to said com mon coupling line, and, in a third coupling switch state, said signal on said respective antenna line is not coupled to said com mon coupling line, the method comprising controlling each of said plurality of coupling switches corresponding to said plurality of coupling structures.

Item 38. The method according to Item 37, wherein each of said coupling structures being configured to couple a signal on said common coupling line to said respective antenna line, and said coupling switch of each of said coupling structures is configured such that, in said first coupling switch state, said signal on said com mon coupling line is coupled to said respective antenna-side antenna line portion, and, in said second coupling switch state, said signal on said common coupling line is coupled to said respective opposite-side antenna line portion.

Item 39. The method according to Item 37 or 38, wherein said com mon coupling line is connected to a switching unit configured to, in a first switching unit state, interconnect said common coupling line with a reception line connectable to a reception circuit, and the method further comprises controlling said switching unit. Item 40. The method according to Item 39, wherein said switching unit is configured to, in a second switching unit state, interconnect said com mon coupling line with a transm ission line connectable to a transm ission circuit.

Item 41 . The method according to Item 39 or 40, wherein said switching unit is configured to, in a third switching unit state, interconnect one of said plurality of antenna lines with said reception line.

Item 42. The method according to any of Items 39 to 41 , wherein said switching unit includes a first switch and a second switch, said first switch is configured to, in said first switching unit state, interconnect said reception line with a first interconnection line, and said second switch is configured to, in said first switching unit state, interconnect said first interconnection line with said common coupling line.

Item 43. The method according to Item 42, wherein said second switch is configured to, in said second switching unit state, interconnect said transmission line with said com mon coupling line.

Item 44. The method according to Item 42 or 43, wherein said switching unit includes a third switch, said first switch is configured to, in said third switching unit state, interconnect said reception line with a second interconnection line, and said third switch is configured to, in said third switching unit state, interconnect said second interconnection line with said one of said plurality of antenna lines.

Item 45. The method according to any of Items 39 to 41 , wherein said switching unit includes a first switch, a second switch, and a third switch, said first switch is configured to, in said first switching unit state, interconnect said reception line with a first interconnection line, said second switch is configured to, in said first switching unit state, interconnect said first interconnection line with a second interconnection line, and said third switch is configured to, in said first switching unit state, interconnect said second interconnection line with said com mon coupling line.

Item 46. The method according to Item 45, wherein said second switch is configured to, in said second switching unit state, interconnect said transmission line with said second interconnection line, and said third switch is configured to, in said second switching unit state, interconnect said second interconnection line with said com mon coupling line.

Item 47. The method according to Item 45 or 46, wherein said switching unit includes a fourth switch and a fifth switch, said first switch is configured to, in said third switching unit state, interconnect said reception line with a third interconnection line, said fourth switch is configured to, in said third switching unit state, interconnect said third interconnection line with a fourth interconnection line, and said fifth switch is configured to, in said third switching unit state, interconnect said fourth interconnection line with said one of said plurality of antenna lines.

Item 48. The method according to any of Items 39 to 47, wherein said antenna control apparatus further comprises said reception circuit, said reception line is connected to said reception circuit, and said reception circuit includes a calibration unit configured to perform calibration measurement and a linearization unit configured to perform linearization processing.

Item 49. The method according to any of Items 41 to 48, further comprising in a normal transmission and reception operation mode of said plurality of antennas, controlling each of said plurality of coupling switches to assume said third coupling switch state, and controlling said switching unit to assume said third switching unit state.

Item 50. The method according to any of Items 41 to 49, further comprising in a transmission calibration mode of at least one of said plurality of antenna lines, controlling at least one of said plurality of coupling switches corresponding to said at least one of said plurality of antenna lines to assume said first coupling switch state, and controlling said switching unit to assume said first switching unit state.

Item 51 . The method according to any of Items 41 to 50, further comprising in a reception calibration mode of at least one of said plurality of antenna lines, controlling at least one of said plurality of coupling switches corresponding to said at least one of said plurality of antenna lines to assume said first coupling switch state, and controlling said switching unit to assume said second switching unit state.

Item 52. The method according to any of Items 41 to 51 , further comprising in a linearization mode of at least one of said plurality of antenna lines, controlling at least one of said plurality of coupling switches corresponding to said at least one of said plurality of antenna lines to assume said first coupling switch state or said second coupling switch state, and controlling said switching unit to assume said first switching unit state. Item 53. The method according to any of Items 37 to 42, wherein a respective portion of at least two of said plurality of antenna lines is embodied as a common antenna line portion, each filter circuitry of said at least two of said plurality of antenna lines is embodied as a com mon filter circuitry, and said common filter circuitry is arranged in said common antenna line portion.

Item 54. The method according to any of Items 37 to 53, wherein said antenna control apparatus further comprises said plurality of antennas, and said plurality of antenna lines is connected to said plurality of respective antennas.

Item 55. A controller of an antenna control apparatus comprising said controller, a plurality of antenna lines connectable to a plurality of respective antennas, each of said antenna lines including a filter circuitry dividing said respective antenna line into an antenna-side antenna line portion and an opposite-side antenna line portion, a com mon coupling line, and a plurality of coupling structures corresponding to said plurality of respective antenna lines, each of said coupling structures being configured to couple a signal on said respective antenna line to said com mon coupling line, wherein each of said coupling structures includes a coupling switch configured such that, in a first coupling switch state, said signal on said respective antenna-side antenna line portion is coupled to said com mon coupling line, in a second coupling switch state, said signal on said respective opposite-side antenna line portion is coupled to said com mon coupling line, and, in a third coupling switch state, said signal on said respective antenna line is not coupled to said com mon coupling line, the controller comprising at least one processor, at least one memory including computer program code, and at least one interface configured for comm unication with at least another apparatus, the at least one processor, with the at least one memory and the computer program code, being configured to cause the controller to perform the method according to any of Items 37 to 54.

Item 56. A computer program product comprising computer-executable computer program code which, when the program is run on a computer, is configured to cause the computer to carry out the method according to any one of Items 37 to 54.

Item 57. The computer program product according to Item 56, wherein the computer program product comprises a computer-readable medium on which the computer-executable computer program code is stored, and/or wherein the program is directly loadable into an internal memory of the computer or a processor thereof.

List of acronyms and abbreviations

3GPP Third Generation Partnership Project

A/D Analogue-to-Digital (conversion) att attenuator

BW bandwidth

CalLNA low noise amplifier in calibration TX path

CalRX calibration receiver

CAZAC constant amplitude zero autocorrelation

D/A Digital-to-Analogue (conversion)

DPD digital pre-distortion

FB feedback

FDD frequency division duplex

HW hardware

Lin linearization

LNA low-noise amplifier mMI MO massive m ultiple input m ultiple output

OTA over-the-air PA power amplifier

RF radio frequency

Rx, RX reception, receiver

SNR signal-to-noise-ratio TDD time division duplex

TRX transceiving, transceiver

Tx, TX transm ission, transm itter

UE user equipment

V2X vehicle-to-everything