TECHNICAL FIELD The proposed technology generally relates to an antenna system for dual transmission, a method for controlling such an antenna system as well as a device configure to perform the method.

BACKGROUND

Existing antenna systems that can be used in tele-communication environments typically comprises a radio unit that is connected to the antenna via cables. A particular antenna of such an antenna system may be built up of several antenna elements and may be configured to generate a radiation pattern that is intended to cover a cell sector that e.g. may be 120 degrees in case of a three-sector site. The plurality of antenna elements may be arranged in rows and columns where a column covers the whole sector and the rows are phase aligned to generate a narrow beam in the vertical plane. The only adjustment is the tilt of the main lobe in the vertical plane because the beam is rather thin and needs adjustments to the surroundings.

Another particular way to transmit radiation is to add beam steering functionality. Instead of transmitting the power to the whole sector, as was the case above, the antenna instead generates a beam to point at particular direction, e.g. a particular user device within the cell sector. The beam steering, or beam forming, is achieved by phase matching the antenna elements in both in horizontal direction and the vertical direction. In this way the energy can be concentrated to the directions where it is used and the overall disturbance of the radiation, caused by e.g. scattering from buildings or other structures within the environment, may be reduced. Beam steering transmission has become very important in 5G-technology due to the fact that 5G- technology utilizes high-frequency radiation. High frequency radiation is more prone to interact with obstacles within the cell than is low frequency radiation. The interaction between the high frequency radiation and possible obstacles in the environment will therefore cause significant disturbances on whole cell sector transmissions due to scattering and refraction. Beam steering transmissions, or beam formed transmissions, provides a way to counter these types of problems within 5G- technology. Beam steering, or beam forming transmission, is moreover a suitable means for reducing the overall signal level within an area since energy is only transmitted to directions where it is needed, e.g. to a direction where the energy is expected to be detected.

In order to have the ability to perform both whole cell sector transmissions as well as beam formed, or beam steered, transmissions several antennas needs to be utilized. Adding more antennas to a particular antenna site is however problematic due to physical limitations such as weight and wind load on the tower. There is also the added commercial drawbacks such as tower rent costs and finding suitable antenna sites. These drawbacks together makes adding more antennas problematic. The proposed technology aims to at least partially alleviate the drawbacks in the art by providing mechanisms allowing a flexible use of already existing and present antenna systems.

SUMMARY

It is an object of the proposed technology to provide mechanisms whereby it will be possible to provide a single antenna column within an antenna system with the ability to perform a dual transmission of radiation by means of transmitting using different transmission modes, one of the transmission modes being beam formed transmissions.

It is another object to provide an antenna system whereby it will be possible to simultaneously transmit radiation by means of different transmission modes from the same antenna column, one transmission mode being beam formed transmissions.

It is still another object to provide a method for controlling an antenna system that is capable to simultaneously transmit radiation by means of different transmission modes from the same antenna column.

It is yet another object to provide devices configured to control an antenna system that is capable to simultaneously transmit radiation by means of different transmission modes from the same antenna column. A further object is to provide a computer program for controlling an antenna system that is capable to simultaneously transmit radiation by means of different transmission modes from the same antenna column. These and other objects are met by embodiments of the proposed technology.

According to a first aspect, there is provided an antenna system for dual transmission. The antenna system comprising an antenna column carrying a plurality of antenna elements. The plurality of antenna elements comprises a first set of antenna elements dedicated to a first radio unit for performing a first mode of transmission. The plurality of antenna elements also comprises a second set of antenna elements dedicated to a second radio unit for performing a second mode of transmission. The second mode of transmission being different from the first mode of transmission and comprising beam formed transmissions. The first set and the second set of antenna elements of the antenna column being adapted to perform transmissions according to the first and second modes of transmission simultaneously.

According to a second aspect there is provided a method for controlling an antenna system adapted for dual transmission. The antenna system comprising an antenna column carrying a plurality of antenna elements. The method comprises selecting among the plurality of antenna elements, a first set of antenna elements and a second set of antenna elements. The method also comprises assigning the first set of antenna elements to a first radio unit adapted for performing a first mode of transmission and the second set of antenna elements to a second radio unit for performing a second mode of transmission, different from the first mode of transmission and comprising beam formed transmissions. The method also comprises initiating a feeding of the first and the second set of antenna elements from the corresponding first and second radio unit to enable the first mode of transmission and the second mode of transmission to be performed simultaneously from the antenna column.

According to a third aspect there is provided a control unit for an antenna system adapted for dual transmission. The antenna system comprising an antenna column carrying a plurality of antenna elements. The control unit is configured to select, among the plurality of antenna elements, a first set of antenna elements and a second set of antenna elements. The control unit is also configured to assign the first set of antenna elements to a first radio unit adapted for performing a first mode of transmission and the second set of antenna elements to a second radio unit for performing a second mode of transmission, different from the first mode of transmission and comprising beam formed transmissions. The control unit is also configured to initiate a feeding of the first and the second set of antenna elements from the corresponding first and second radio unit to enable the first mode of transmission and the second mode of transmission to be performed simultaneously from the antenna column.

According to a fourth aspect of the proposed technology there is provided a computer program for controlling an antenna system adapted for dual transmission, the antenna system comprising an antenna column carrying a plurality of antenna elements, the computer program comprising instructions, which when executed by at least one processor, cause the at least one processor to:

• select, among plurality of antenna elements, a first set of antenna elements and a second set of antenna elements;

• assign the first set of antenna elements to a first radio unit adapted for performing a first mode of transmission and assign the second set of antenna elements to a second radio unit for performing a second mode of transmission, different from the first mode of transmission and comprising beam formed transmissions; and

^• output the assignment of the antenna elements to be communicated to the radio units; and

• initiating a feeding of the first and the second set of antenna elements from the corresponding first and second radio unit to enable the first mode of transmission and the second mode of transmission to be performed simultaneously from the antenna column .

According to a fifth aspect of the proposed technology there is provide an apparatus for controlling an antenna system adapted for dual transmission, the antenna system comprising an antenna column carrying a plurality of antenna elements, the apparatus comprises a processing module, for selecting, among plurality of antenna elements, a first set of antenna elements and a second set of antenna elements, and assigning the first set of antenna elements to a first radio unit adapted for performing a first mode of transmission and assign the second set of antenna elements to a second radio unit for performing a second mode of transmission, different from the first mode of transmission and comprising beam formed transmissions. The apparatus also comprises an output module for outputting the assignment of the antenna elements to be communicated to the radio units. The apparatus also comprises an initiation module for initiating a feeding of the first and the second set of antenna elements from the corresponding first and second radio unit to enable the first mode of transmission and the second mode of transmission to be performed simultaneously from the antenna column.

Embodiments of the proposed technology makes it possible to keep the number of antennas as well as antenna elements low. A beam steering system requires a large antenna matrix with more antenna elements than existing antenna systems. By using the proposed architecture of antenna elements an existing system for whole cell transmissions uses the same antenna matrix as the beam steering system. Moreover, the proposed technology allows one to skip adding more antennas to the site when introducing a complementary beam steering system. Adding antennas to the site is often hard because of lack of space in the mast. More antennas will also add costs.

Other advantages will be appreciated when reading the detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS The embodiments, together with further objects and advantages thereof, may best be understood by making reference to the following description taken together with the accompanying drawings, in which:

FIG. 1 A is a schematic illustration of radio units connected to a common antenna column over corresponding phase shifters.

FIG. 1 B is a schematic block diagram illustrating a traditional radio unit that can be used for transmitting and receiving information in the form of electromagnetic radio waves. FIG. 2 is a schematic diagram illustrating an embodiment of an antenna system for dual transmission according to the proposed technology. A particular set of antenna elements are used for traditional radio transmission and a subset of the antenna elements are used for beam formed radio transmissions.

FIG. 3A is a schematic diagram illustrating how a radio unit for traditional, whole cell- sector transmissions are connected to antenna elements of an antenna column. FIG. 3B is a schematic diagram illustrating how a radio unit for beam formed radio transmission is connected to the antenna elements of an antenna column.

FIG. 3C is a schematic diagram illustrating how different radio units may be connected to a common antenna column according to a particular embodiment of the proposed technology.

FIG. 4 is a schematic diagram illustrating an antenna system for dual transmission according to the proposed technology. The antenna system comprises two antenna columns.

FIG.5A is a schematic diagram illustrating how a control unit for controlling the antenna system according to the proposed technology ca be implemented.

FIG. 5B provides a more detailed illustration of some of the features illustrated in FIG. 5A.

FIG. 6 is a flow diagram illustrating a method for controlling an antenna system for dual transmission according to the proposed technology.

FIG. 7 is a block diagram illustrating a control unit configured to control an antenna system for dual transmission according to the proposed technology.

FIG.8 is a block diagram illustrating a computer program implementation that can be used to control an antenna system according to the proposed technology.

FIG. 9 is a flow diagram illustrating an apparatus configured to control an antenna system for dual transmission according to the proposed technology.

DETAILED DESCRIPTION Throughout the drawings, the same reference designations are used for similar or corresponding elements. For a better understanding of the proposed technology, it may be useful to begin with a brief system overview and an analysis of the technical problem.

FIG. 1 is a schematic flow diagram illustrating an example of an existing antenna system for performing traditional transmissions. With traditional transmissions is intended a transmission mode where radiation intended to cover the whole, or at least a large part, of a cell sector is transmitted. To this end a radio unit 100 of a certain effect is connected to an antenna column 10. The depicted antenna column 10 comprises a plurality of antenna elements 15. The radio unit is connected to each of the antenna elements over a phase shifter 19. Also depicted is another optional radio unit 100 ^* of a possibly different effect that is also connected to the antenna elements 15 over a corresponding phase shifter 19 ^* . The second radio unit 100 ^* also performs traditional radio transmissions according to the same transmission mode that was used by the radio unit 100. The radio units 100; 100 ^* may also be connected to the antenna elements 15 over a diplexer, the diplexer is not shown in the drawing. A diplexer is a passive device that can be used to implement frequency-domain multiplexing. To this end two different ports are multiplexed onto a third port. The different ports may carry signals that occupy different frequency bands hence making it possible for the different signals to coexist on the third port without experiencing any interference. The diplexers, or the diplex filters, combine the signals from the phase shifter for each radio unit or system/frequency. An antenna structure with distributed diplexers, or diplex filters, may be used in order to generate individual tilts of the radiation lobes for the different systems. With radio unit is herein intended a device that takes information e.g. digital information, as input, converts the information to a representation suitable for transmissions and feeds an antenna in order to transmit the information by means of a particular transmission mode. A circuit diagram for a traditional radio unit that takes digital information as input and output radio, and vice versa, is schematically illustrated in the block diagram of FIG.1 B. The radio unit 100 of FIG.1 B comprises a digital front end 101 , a digital up converter 102 and a digital down converter 108. It also comprises a power amplifier 103, a low noise amplifier 107, an isolator 104, a coupler 105 and a duplex filter unit 106. An antenna system as the one described above with reference to FIG.1 may therefore be used by different radio units for transmitting traditional radio. Traditional radio is however not a completely suitable transmission mode when using carriers of really high frequencies, as is the case with 5G-technology, since the high frequencies are more prone to interact with obstacles in the environment between the antenna and the intended receiver. This will lead to refractions and scattering of the waves which will in turn negatively affect the quality of the transmission. To overcome some of the inherent problems with high frequency transmissions it is preferred to use beam formed, or beam steering, transmissions for the high frequency transmissions. Beam formed transmissions may be described as a transmission mode where whole cell sector transmissions are replaced by more localized transmissions, e.g. a narrow beam is generated in the direction of a possible receiver. Introducing beam steering in 5G-networks as well as in Long Term Evolution networks, LTE-networks, requires that an antenna matrix is provided. The proposed technology aims to provide a particular antenna architecture that extends the existing systems transmission capabilities, e.g. the capability to perform whole cell transmissions, to also allow the capability to perform beam steering or beam formed transmissions. Such an antenna system having dual transmission capabilities would reduce the need to add more antennas at the site.

According to the proposed technology there is thus provided an antenna system 1 for dual transmission. The antenna system comprising an antenna column 10 carrying a plurality of antenna elements 15. The plurality of antenna elements 15 comprises a first set 16 of antenna elements dedicated to a first radio unit 100 for performing a first mode of transmission. The plurality of antenna elements 15 also comprises a second set 17 of antenna elements dedicated to a second radio unit 200 for performing a second mode of transmission. The second mode of transmission being different from the first mode of transmission and comprising beam formed transmissions. The first set 16 and the second set 17 of antenna elements 15 of the antenna column 10 being adapted to perform transmissions according to the first and second modes of transmission simultaneously. FIG. 2 provides a schematic illustration of an example of such an antenna system.

In other words, the antenna elements 15 of the antenna column 10 of the antenna system are shared between two different radio units 100; 200 that aims to transmit radiation according to different transmission modes. The first radio unit 100 is dedicated to a particular set 16 of the antenna elements 15 with the intention to perform transmissions according to a first transmission mode. At the same time is another set 17 of antenna elements dedicated to the second radio unit 200 with the intention to perform transmissions according to a second transmission mode. The second transmission mode is different from the first transmission mode used by the first radio unit 100 and it comprises to transmit beam formed transmissions. This allows for a dual transmitting antenna system where radiation may be transmitted according to the different first and second transmission modes simultaneously and from the same antenna column 10. With simultaneously is here intended that the different transmissions is performed with at least an overlap in time. One of the transmission mode of the dual transmitting antenna system is thus beam formed transmissions. This particular way of transmitting energy is beneficial in that it provides a suitable means for reducing the overall signal level within an area. This is due to the fact that a beam formed transmission mode only transmit energy transmitted to directions where it is needed, e.g. to those directions where the energy is expected to be detected, e.g. to the location of a User Equipment within a served cell or cell sector. The proposed technology may be used as an effective mechanism that enables a reduction of the overall signal level in an area such as a cell or cell-sector. The proposed technology provides this mechanism while at the same time ensuring that there is no need to add further antennas and at cost of only a possible minor increase in size, depending on the number of antenna columns used. Particular embodiments of the proposed technology may with advantage be used for antennas with frequencies at, or below, 10 GHz, where the antenna sizes are large and the proposed dual transmission provides an efficient with only a minor relative size increase. The proposed technology may however also be used for very high frequency beam forming, e.g. in 5G-technology, with only minor modifications. To further clarify some aspects of the proposed technology reference is made to FIGs 3A-3C. FIG. 3A provides an illustration of an example of an antenna column 10 that is used by a single radio unit 100. The radio unit 100 is connected to the antenna elements 15 of the antenna column 10 over a phase shifter 19. FIG.3B illustrates a particular example of how a second radio unit 200, intended to perform beam formed transmissions, may be connected to all of the antenna elements 15 of the antenna column 10. It is also illustrated how the radio unit 200 comprises a plurality of radios 200 ^* that are each connected to a corresponding antenna element 15. FIG. 3C illustrates how the radio unit 100 and the radio unit 200 may be connected to the antenna elements 15 in order to enable a dual transmitting antenna system. In this particular example is the radio units connected to the antenna elements over diplexers 18.

The proposed technology therefore mixes the usage of a particular antenna column between e.g. a first transmission mode corresponding to traditional radio transmissions and a second transmission mode corresponding to beam steering or beam formed radio. The antenna elements in an antenna column are thus shared between traditional radio and the beam steering system in a highly efficient way that enables the use of existing antenna columns even for very different transmission modes. It should be noted that the radio unit 200 for beam formed transmission may be an antenna integrated beam steering radio. The traditional system uses the full column as one while the beam steering system groups the elements to be able to form vertical beams. A particular embodiment of the proposed technology provides an antenna system 1 wherein the first mode of transmission comprises a mode of transmission where radiation is transmitted to cover substantially a whole cell sector. That is, the first mode of transmission may be a conventional radio transmission covering a whole cell sector, e.g. a sector with 120 degrees angular extension that form part of a three-sector site.

According to another embodiment of the proposed technology there is provided an antenna system 1 wherein the second set 17 of antenna elements comprises at least two of the first set 16 of antenna elements. Dedicating at least two of the antenna elements 15 to the second radio unit will ensure that a beam forming second transmission mode is enabled.

Yet another embodiment of the proposed technology provides an antenna system 1 wherein the first set 16 of antenna elements comprises all the antenna elements 15 of the antenna column 10. This particular embodiment allows the first radio unit to transmit traditional radio using the full antenna column as one while the beam steering system may utilize some a grouping of a subset of the antenna elements in order to form vertical beams.

Still another particular embodiment of the proposed technology provides an antenna system 1 wherein the first set 16 of antenna elements 1 5 is identical to the second set 17 of antenna elements 15, whereby each antenna element 15 of the antenna column 10 is adapted to simultaneously perform both the first mode of transmission and the second mode of transmission. This embodiment ensures that all the antenna elements 15 of the antenna column may be utilized for dual transmission.

By way of example, the proposed technology also provides an antenna system 1 wherein the second set 17 of antenna elements comprises a plurality of antenna elements 15, the antenna elements 15 being combined into at least two groups of antenna elements each group being adapted to perform the second mode of transmission.

A particular embodiment of the proposed technology provides for an antenna system wherein the second radio unit 200 and the first radio unit 100 are combined to a common antenna element.

An alternative embodiment provides an antenna system wherein the second radio unit 200 and the first radio unit 100 are connected to a common antenna element over a diplexer 18. An example of such an antenna system is illustrated in FIG.3C.

An optional embodiment of the proposed system provides an antenna system 1 wherein the antenna system comprises a plurality of antenna columns 10, one antenna column 10, 10' for each radio unit 100, 100' connected to the antenna system and adapted to transmitting radiation according to the first transmission mode, wherein a specific one of the plurality antenna columns is dedicated to a corresponding radio unit. This is illustrated in FIG.4. FIG.4 illustrates two particular antenna columns, antenna column 10 and antenna column 10'. Antenna elements 15 of the antenna column 10 are dedicated to first 100 and second 200 radio units for transmitting radiation according to first and second transmission modes as was described earlier. Antenna elements 15' of the antenna column 10' are instead dedicated to first 100' and second 200' radio units for transmitting radiation according to corresponding first and second transmission modes. The various transmission modes may differ between the antenna columns but the second transmission mode of the both the antenna columns may be beam formed transmission.

The main feature of this embodiment is that one may add antenna columns to allow for more diversified transmissions. Each added antenna column may be utilized by two different radio units, one radio unit for traditional transmission and one for beam formed transmission. The first 10 and second antenna column 10' may be used for the same beam formed transmission. This is beneficial for Active Antenna Systems, AAS system, since the use of more than one antenna column provides for a better beam forming capacity. In that case the passive system, i.e. the system performing traditional whole cell-sector transmissions, is mixed with the AAS system in each antenna column. The radio unit 100 may use all the antenna elements of the antenna column for the same signal while the more active radio unit, e.g. the AAS system, transmits different signals to different groups of antenna elements to form a beam.

As an example, consider the case where an initial antenna system comprises two antenna columns used for traditional radio transmission, i.e. not beam formed transmission, if two more antenna columns are added to such an antenna system, in order to get 4 columns, the addition of antenna columns frees the diplex port from the traditional system so that it can be used by the beam steering system.

The proposed antenna system 1 may be used as part of a radio base station or network node to enable transmission of information to a wireless communication device. The same antenna system may thus be used to transmit both traditional radio, e.g. transmission covering substantially all of a cell-sector, as well as beam formed radio from the same antenna column. As used herein, the non-limiting terms "wireless communication device", "station", "User Equipment UE", and "terminal" may refer to a mobile phone, a cellular phone, a Personal Digital Assistant PDA, equipped with radio communication capabilities, a smart phone, a laptop or Personal Computer PC, equipped with an internal or external mobile broadband modem, a tablet with radio communication capabilities, a target device, a device to device UE, a machine type UE or UE capable of machine to machine communication, Customer Premises Equipment CPE, Laptop Embedded Equipment LEE, Laptop Mounted Equipment LME, USB dongle, a portable electronic radio communication device, a sensor device equipped with radio communication capabilities or the like. In particular, the term "wireless communication device" should be interpreted as non-limiting terms comprising any type of wireless device communicating with a network node in a wireless communication system and/or possibly communicating directly with another wireless communication device. In other words, a wireless communication device may be any device equipped with circuitry for wireless communication according to any relevant standard for communication.

As used herein, the non-limiting term "network node" may refer to base stations, access points, network control nodes such as network controllers, radio network controllers, base station controllers, access controllers, and the like. In particular, the term "base station" may encompass different types of radio base stations including standardized base station functions such as Node Bs, or evolved Node Bs eNBs, and also macro/micro/pico radio base stations, home base stations, also known as femto base stations, relay nodes, repeaters, radio access points, Base Transceiver Stations BTSs, and even radio control nodes controlling one or more Remote Radio Units RRUs, or the like.

Having described the proposed antenna system in great detail, below is provided a description of a proposed method that can be used to control the described antenna system, to this end there is provided a method for controlling an antenna system that is adapted for dual transmission. The antenna system comprising an antenna column 10 carrying a plurality of antenna elements 15. The method comprises selecting S1 , among the plurality of antenna elements 15, a first set 16 of antenna elements and a second set 17 of antenna elements. The method also comprises assigning S1 the first set of antenna elements to a first radio unit 100 adapted for performing a first mode of transmission and the second set 17 of antenna elements to a second radio unit 200 for performing a second mode of transmission, different from the first mode of transmission and comprising beam formed transmissions. The method also comprises initiating S3 a feeding of the first 16 and the second 17 set of antenna elements from the corresponding first 100 and second 200 radio unit to enable the first mode of transmission and the second mode of transmission to be performed simultaneously from the antenna column 10. A flow diagram illustrating the method is provided in FIG. 6.

In other words, the method aims to provide mechanisms whereby the earlier described antenna system for dual transmission may be controlled in order to ensure that the radio units perform timely transmissions of the first and second transmission mode. The method may begin by selecting S1 the particular sets of the antenna elements that should be used for a particular transmission mode, i.e. a first or a second transmission mode where the second transmission mode comprises beam formed transmissions. The method may proceed and assign, in a step S2, the different sets of antenna element to a corresponding radio unit. The step of selecting and assigning particular sets to corresponding radio units may be performed manually, e.g. by manually connecting specified antenna elements to corresponding radio units through cables or wires. The method also comprises the step S3 of initiating a feeding of the different antenna elements from corresponding radio units. By initiating the feeding of selected and assigned antenna elements the method may ensure, in a controlled manner, a simultaneous transmission of radiation according to the first and second transmission mode from the single antenna column. A particular embodiment of the proposed method provides a method wherein the step of selecting S1 comprises selecting all antenna elements 15 of the antenna column as the first set of antenna elements and selecting at least two of the antenna elements 15 as the second set of antenna elements. Another embodiment of the proposed method provides a method wherein the step of selecting S1 comprises selecting all antenna elements 15 of the antenna column as the second set of antenna elements.

Yet another embodiment of the proposed method provides a method that also comprises the step of combining antenna elements of the second set 17 of antenna elements 15 into at least two groups of antenna elements, whereby each of the at least two groups are adapted to perform transmissions according to the second mode of transmission.

Still another embodiment of the proposed technology provides a method wherein the step of assigning S1 comprises assigning the first set of antenna elements to the first radio unit 100 adapted for performing a first mode of transmission in the form of radiation transmitted to cover substantially a whole cell sector and assigning the second set of antenna elements to the second radio unit 200 for performing a second mode of transmission in the form of beam formed transmissions.

The proposed technology also provides for a control unit that is configured to perform the proposed method described above. This control unit may in particular be used when the physical connection between the radio units 100; 200 and the antenna elements already have been accomplished, i.e. the connections between the radio units and the antenna elements have been established physically. The control unit may then automatically control the dual transmission mode in a way to be described.

A particular aspect of the proposed technology therefore provides a control unit 1000 for an antenna system 1 adapted for dual transmission. The antenna system comprising an antenna column 10 carrying a plurality of antenna elements 15. The control unit 1000 is configured to select, among the plurality of antenna elements 15, a first set 16 of antenna elements and a second set 17 of antenna elements. The control unit 1000 is also configured to assign the first set of antenna elements to a first radio unit 100 adapted for performing a first mode of transmission and the second set 17 of antenna elements to a second radio unit 200 for performing a second mode of transmission, different from the first mode of transmission and comprising beam formed transmissions. The control unit 1000 is also configured to initiate a feeding of the first 16 and the second 17 set of antenna elements from the corresponding first 100 and second 200 radio unit to enable the first mode of transmission and the second 5 mode of transmission to be performed simultaneously from the antenna column 10.

In other words, if there is an existing physical connection established between the radio units and the antenna elements the control unit may control the antenna system by automatically selecting and assigning particular antenna elements to the radio

10 units. Having allocated specific antenna element resources to the radio units the control unit can trigger a simultaneous transmission of the different transmission modes by e.g. sending an initiating signal to the radio units. A particular embodiment of the proposed technology where a control unit 1000 is employed is illustrated in FIG.5A. The control unit 1000 is connected, and able to communicate to, the radio unit

15 200. It should be noted that if the radio unit 200 comprises a plurality of radios 200 ^* , each feeding a particular antenna element, the radio unit 200 may comprise a central node 205 that is able to communicate with each of the radios 200 ^* . The central node takes an incoming data stream as input and processes the data stream and provide weights in order to perform beam forming. The processed and weighted data stream

20 may then be communicated to the various radios 200 ^* . This implementation is illustrated in more detail in FIG. 5B. The control unit 1000 may also be connected to the radio unit 100. It may in particular be connected to the radio unit 100 in order to initiate the feeding of the antenna elements allocated to the radio unit 100 to enable a simultaneous transmission from both the first 16 and second 17 set of antenna

25 elements. As a particular example of how such an embodiment may be used, consider the case where the radio unit 200 comprises a plurality of radios 200 ^* , as many radios 200 ^* as there is antenna elements 15 of the antenna column 10. Each individual radio 200 ^* is connected to a corresponding antenna element 15. Consider moreover that the radio unit 100 is connected to each individual antenna element 15. The control unit

30 1000 may now be configured to select and assign sets of antenna elements to be used by individual radios 200 ^* and a particular set to be used by the radio unit 100. Having assigned the particular sets to the radio units 100; 200 the control unit 1000 may initiate a simultaneous transmission from the radio units 100; 200, e.g. by communicating information that a particular time or a particular time window should be used for transmission.

Below there will be described certain embodiments of the proposed control unit 1000. These embodiments provides particular ways of implementing the earlier described method.

One particular embodiment provides a control unit 1000 that is configured to select all antenna elements 15 of the antenna column as the first set of antenna elements and configured to select at least two of the antenna elements 15 as the second set of antenna elements.

Another embodiment of a control unit provides a control unit 1000 that is configured to select all antenna elements 15 of the antenna column as the second set of antenna elements.

Yet another embodiment provides a control unit 1000 that is further configured to combine antenna elements belonging to the second set 17 of antenna elements 15 into at least two groups of antenna elements.

Still another embodiment provides a control unit 1000 that is configured to assign the first set of antenna elements to the first radio unit 100 adapted for performing a first mode of transmission in the form of radiation transmitted to cover substantially a whole cell sector and assigning the second set of antenna elements to the second radio unit 200 for performing a second mode of transmission in the form of beam formed transmissions.

FIG. 7 provides a block diagram illustration of a particular embodiment of the control unit 1000. Illustrated is a control unit 1000 that comprises at least one processor 1 100 and memory 1200, the memory 1200 comprising instructions, which when executed by the at least one processor 1 100, cause the at least one processor 1 100 to control an antenna system for dual transmission. FIG.7 also illustrates schematically that the control unit 1000 may be provided with a communication circuitry 1300 to enable signalling to radio units.

It will be appreciated that the methods and arrangements described herein can be implemented, combined and re-arranged in a variety of ways.

For example, embodiments may be implemented in hardware, or in software for execution by suitable processing circuitry, or a combination thereof. The steps, functions, procedures, modules and/or blocks described herein may be implemented in hardware using any conventional technology, such as discrete circuit or integrated circuit technology, including both general-purpose electronic circuitry and application-specific circuitry. Alternatively, or as a complement, at least some of the steps, functions, procedures, modules and/or blocks described herein may be implemented in software such as a computer program for execution by suitable processing circuitry such as one or more processors or processing units. Examples of processing circuitry includes, but is not limited to, one or more microprocessors, one or more Digital Signal Processors DSPs, one or more Central Processing Units CPUs, video acceleration hardware, and/or any suitable programmable logic circuitry such as one or more Field Programmable Gate Arrays FPGAs, or one or more Programmable Logic Controllers PLCs.

The processing circuitry including one or more processors 1 100 is thus configured to perform, when executing the computer program 1350, well-defined processing tasks such as those described herein. The processing circuitry does not have to be dedicated to only execute the above- described steps, functions, procedure and/or blocks, but may also execute other tasks. According to the proposed technology there is provided a computer program for controlling an antenna system adapted for dual transmission, the antenna system comprising an antenna column 10 carrying a plurality of antenna elements 15, a comprising instructions, which when executed by at least one processor, cause the at least one processor to:

• select, among plurality of antenna elements 15, a first set 16 of antenna elements and a second set 17 of antenna elements;

• assign the first set of antenna elements to a first radio unit 100 adapted for performing a first mode of transmission and assign the second set 17 of antenna elements to a second radio unit 200 for performing a second mode of transmission, different from the first mode of transmission and comprising beam formed transmissions; and

• output the assignment of the antenna elements to be communicated to the radio units; and

• initiating a feeding of the first 16 and the second 17 set of antenna elements from the corresponding first 100 and second 200 radio unit to enable the first mode of transmission and the second mode of transmission to be performed simultaneously from the antenna column 10.

The processing circuitry including one or more processors 1 100 is thus configured to perform, when executing the computer program 1350, well-defined processing tasks such as those described herein. FIG. 8 provides an illustration of a computer program 1350 implemented in a control unit 1000.

The proposed technology also provides a carrier 1400 comprising the computer program, wherein the carrier is one of an electronic signal, an optical signal, an electromagnetic signal, a magnetic signal, an electric signal, a radio signal, a microwave signal, or a computer-readable storage medium.

The flow diagram or diagrams presented herein may thus be regarded as a computer flow diagram or diagrams, when performed by one or more processors. A corresponding apparatus may also be defined as a group of function modules, where each step performed by the processor corresponds to a function module. In this case, the function modules are implemented as a computer program running on the processor. The term 'processor' should be interpreted in a general sense as any system or device capable of executing program code or computer program instructions to perform a particular processing, determining or computing task. The computer program residing in memory may thus be organized as appropriate function modules configured to perform, when executed by the processor, at least part of the steps and/or tasks described herein.

FIG. 9 is a schematic diagram illustrating an example of an apparatus 500 for controlling an antenna system adapted for dual transmission, the antenna system comprising an antenna column 10 carrying a plurality of antenna elements 15, the apparatus 500 comprises a processing module 510, for selecting, among plurality of antenna elements 15, a first set 16 of antenna elements and a second set 17 of antenna elements, and assigning the first set 16 of antenna elements to a first radio unit 100 adapted for performing a first mode of transmission and assign the second set 17 of antenna elements to a second radio unit 200 for performing a second mode of transmission, different from the first mode of transmission and comprising beam formed transmissions. The apparatus 500 also comprises an output module for outputting the assignment of the antenna elements to be communicated to the radio units. The apparatus also comprises an initiation module for initiating a feeding of the first 16 and the second 17 set of antenna elements from the corresponding first 100 and second 200 radio unit to enable the first mode of transmission and the second mode of transmission to be performed simultaneously from the antenna column 10. Alternatively it is possible to realize the modules in FIG. 9 predominantly by hardware modules, or alternatively by hardware, with suitable interconnections between relevant modules. Particular examples include one or more suitably configured digital signal processors and other known electronic circuits, e.g. discrete logic gates interconnected to perform a specialized function, and/or Application Specific Integrated Circuits ASICs as previously mentioned. Other examples of usable hardware include input/output I/O circuitry and/or circuitry for receiving and/or sending signals. The extent of software versus hardware is purely implementation selection. The embodiments described above are merely given as examples, and it should be understood that the proposed technology is not limited thereto. It will be understood by those skilled in the art that various modifications, combinations and changes may be made to the embodiments without departing from the present scope as defined by the appended claims. In particular, different part solutions in the different embodiments can be combined in other configurations, where technically possible.