TECHNICAL FIELD

The present disclosure relates to techniques for interference management in beam-formed communication networks, in particular in 5G New Radio (NR) communication systems. In particular the disclosure relates to Transmit-Receive Points (TRPs) and processing devices of such TRPs and corresponding methods that set up a communication link based on information about a set of High Risk Interfering Beams (HRIBs).

BACKGROUND

To meet the demands of higher data rates, the large amount of available bandwidth at high frequency bands (> 6 GHz) can be exploited. However, to cope with the propagation effects at higher frequencies, beamforming at the transmit (Tx) device and at the receive (Rx) device can be employed. To set up a beam pair link for communication between the Tx device and Rx device, a proper Tx beam at the Tx device 120 and Rx beam at the Rx device 140 need to be selected, e.g., via a beam sweeping procedure. The best beam pair (Tx beam, Rx beam) is usually selected (e.g., by the UE 140 in Fig. 1 ) based on the signal strength, i.e. based on the SNR, and therefore, does not consider interference from interfering Tx devices 1 10. However, neglecting such interference at the Rx device 140 could lead to selecting a beam pair (in particular a Rx beam 141 ), which could receive strong interference 1 12 and result in a transmission with low SINR.

SUMMARY

It is the object of the invention to provide efficient techniques for interference management in beam-formed communication to reduce or even avoid interference and thus improve the quality of the communication link.

This object is achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures. A basic idea of the invention as described hereinafter is to apply an efficient interference management scheme that relies on information about a set of High Risk Interference Beams (HRIBs). The interference management scheme consists of two main aspects.

The first main aspect consists in determining over a group of resource blocks, the set of Tx beams of an interfering Tx device, which are likely to cause interference at a Rx device (interfered Rx device). The Tx beams from an interfering Tx device which are likely to cause interference at a Rx device for a group of resources blocks is referred to as“High-Risk Interference Beams” (HRIBs). A group of resource blocks (RBs) refers to a group of time- frequency resources (not necessarily contiguous) allocated for transmission of a Tx device, similar to a resource block group or precoding resource block group in LTE.

The second main aspect consists in making use of the HRIBs to set up a communication link, in particular a beam pair link, between another Tx device (serving Tx device) and the interfered Rx device. The interfering Tx device can be an interfering TRP or an interfering UE in an aggressor cell. The interfered Rx device can be a TRP in a victim cell, which is receiving an uplink transmission, or a UE in a victim cell, which is not connected to the interfering Tx device and receiving a downlink transmission. Another Tx device can be the serving TRP transmitting in the downlink to the victim UE or a UE transmitting in the uplink to a serving TRP in the victim cell.

The two main aspects of the disclosed interference management scheme can be performed as follows. An interfering Tx device first determines the HRIBs on a group of resource blocks, and afterwards the HRIBs are signalled to the serving TRP in the victim cell. If the serving TRP in the victim cell is the interfered Rx device, then it can make use of the HRIBs for interference management in the uplink. If the interfered Rx device is a UE in the victim cell, the serving TRP in the victim cell can decide which of the received HRIBs to send to the UE, e.g., only a subset of the received HRIBs can be sent to the UE. The UE, as the interfered Rx device, can make use of the signalled HRIBs for interference management in the downlink.

The use of the HRIBs enables an efficient interference management scheme with a reduced signalling overhead and rate compared to prior techniques. In addition, no interference measurements are required at the interfering Tx device and furthermore, the interfering Tx device is not restricted to use a reported HRIB on a given group of resource blocks. The disclosed interference management scheme is of particular relevance to 5G NR standardization.

Thus, a main concept of the invention lies in the determination, signalling and usage of the HRIBs (set of likely to interfere Tx beams) of an interfering Tx device for an interfered Rx device over a group of resource blocks. The HRIBs can be determined at the interfering Tx device as the Tx beams of the interfering Tx device which have a high beam usage probability on the group of resource blocks or as the Tx beams of the interfering Tx device which have a high beam usage probability on the group of resource blocks and which have a high possible interference impact at the interfered Rx device. Afterwards, the HRIBs are signalled to the serving TRP in the victim cell, which can use this information for interference management and/or for selecting a beam pair link for an uplink transmission, if the interfered Rx device is the serving TRP. If the interfered Rx device is a UE in the victim cell, the serving TRP can decide which of the received HRIBs to send to the UE, such that the UE can use the signaled HRIBs when selecting a beam pair link for a downlink transmission.

In general, the HRIBs can be used at the interfered Rx device for selecting a beam pair link for a transmission, by considering potential interference based on interference measurements. For example, the interfered Rx device can avoid potential interference received with a given Rx beam from an interfering Tx beam in the set of HRIBs by choosing another Rx beam.

In the following sections, TRPs, transmit devices and receive devices are described. A transmit device is a device for sending a transmission, and a receive device is a device for receiving the transmission. A transmit device and a receive device may be implemented in a single device; such a device may be referred to as transmit-receive point (TRP). Examples of TRPs include access nodes, evolved NodeBs (eNBs), base stations (BSs), NodeBs, master eNBs (MeNBs), secondary eNBs (SeNBs), remote radio heads, access points, user equipments (UEs), mobiles, mobile stations, terminals, and the like. When referring to an interfering TX device and interfered Rx device, it is actually referring to a potential interfering Tx device and a potential interfered Rx device. In order to describe the invention in detail, the following terms, abbreviations and notations will be used:

UE: User Equipment

BS: Base Station, eNodeB, gNodeB

TRP: T ransmit-Receive-Point

HRIB: High Risk Interfering Beam

SNR: Signal-to-Noise Ratio

CSI-RS: Channel State Information - Reference Signal

Tx: Transmit

Rx: Receive

SSB: Synchronization Signal Block

SRS: Sounding Reference Signal

According to a first aspect, the invention relates to a processing device, in particular a processing device of a Transmit-Receive Point, TRP, for determining a set of high risk interfering beams, HRIBs, wherein the processing device is configured to: determine a set of HRIBs among a set of one or more interfering beams, wherein the set of HRIBs is determined based on statistics of a usage of the one or more interfering beams.

The use of the HRIBs enables an interference management scheme with a reduced signalling overhead and rate compared to prior techniques. In addition, no interference measurements are required at the interfering Tx device and furthermore, the interfering Tx device is not restricted to use a reported HRIB on a given group of resource blocks.

A beam transmitted by a device other than the serving transmit device and the receive device is referred to herein as an interfering beam, regardless of whether or not a signal transmitted with the interfering beam is actually received by the receive device.

The statistics may include probabilities of employing the one or more interfering beams based on past usage and/or expected usage of the one or more interfering beams.

In this disclosure, it is understood that each beam may provide a group of one or more resource blocks, or several groups of resource blocks. A resource block is a block in the time-frequency domain. It is also understood that each of the operations involving beams described herein may be performed for a certain group of one or more resource blocks. By employing the statistics of the usage of the interfering beams, i.e. the probabilities for an interfering Tx device to employ its Tx beams, for determining the HRIBs, such a processing device provides an efficient solution for interference management in mobile radio communications. With the HRIBs available at the interfered Rx device, this enables the interfered Rx device to consider the potential interference that could be received on the different Rx beams without any explicit coordination with the interfering Tx device.

In an exemplary implementation form of the processing device, the statistics are based on past usage and/or expected usage of the one or more interfering beams.

Such statistics can be easily determined since past usage is available at the processing device and expected usage can be determined by evaluating the scheduling of the interfering beams.

In an exemplary implementation form of the processing device, the set of HRIBs is determined for a group of resource blocks.

This provides the advantage that the frequency dependency of the statistics of the usage of the interfering beams and of the scheduling decisions for the group of resource blocks can be exploited.

In an exemplary implementation form of the processing device, the set of HRIBs is determined based further on one or more potential interference impact values of the one or more interfering beams.

The potential interference impact values may be based on the environment, e.g., the location of a victim cell with respect to the interfering Tx device that emits the interfering beams. The potential interference impact values can be based further on feedback from a victim device, e.g., an interfered Rx device, regarding the interfering beams that would have a high interference impact at the victim device.

In an exemplary implementation form of the processing device, the set of HRIBs is determined for an uplink transmission or for a downlink transmission. The interfering Tx device can narrow down the selection of the set of HRIBs based on this information, i.e. distinguish between the interfering Tx beams for a TRP in the uplink (located at a specific point in the cell) or the interfering Tx beams for a UE in the downlink (located in the cell).

According to a second aspect, the invention relates to a transmit-receive point, TRP, in particular an interfering transmit device, including the processing device according to the first aspect or any one of its implementation forms.

Such a TRP can efficiently determine HRIBs, i.e. beams that have a high risk of interfering a transmission to a Rx device. This provides the advantage that the Rx device, being informed about such HRIBs, can select other Rx beams if one Rx beam has a high probability of receiving interference, thereby making transmission more reliable.

A transmit device as denoted above may comprise, for example, a signal processor, a transmitter, and an antenna. Similarly, a receive device may comprise, for example, a signal processor, a transmitter, and an antenna.

It is understood that the word“interfering” in the expressions“interfering transmit device” and“interfering transmit beams” should be interpreted as“potentially interfering”.

In an exemplary implementation form of the TRP, the TRP is configured to generate one or more transmit beams and to provide statistics of a usage of the one or more transmit beams.

This provides the advantage that multiple transmit beams can be compared with respect to their expected usage and interference.

In an exemplary implementation form of the TRP, the TRP is configured to transmit the set of HRIBs to another TRP, in particular to another base station.

This provides the advantage that a TRP in a neighbor cell which is close to the interfering TRP can be informed about the HRIBs. In an exemplary implementation form of the TRP, the TRP is configured to transmit a configuration of a pilot signal to another TRP.

An advantage thereof is that transmitting the configuration of the pilot signal to another TRP enables interference measurements in the victim cell.

According to a third aspect, the invention relates to a processing device, in particular a processing device of a Transmit-Receive Point, TRP, for beam pair selection, wherein the processing device is configured to: select a beam pair from a set of candidate beam pairs for setting up a communication link from a serving transmit device to a receive device via the selected beam pair, wherein each of the candidate beam pairs comprises a transmit beam of the serving transmit device and a receive beam of the receive device, wherein the selection is based on a set of high risk interfering beams, HRIBs, in particular a set of HRIBs determined by the processing device according to the first aspect or any one of its implementation forms.

The set of HRIBs may be determined for a group of resource blocks, for example.

The set of candidate beam pairs may be a finite set or an infinite set. In particular, the set of beam pairs may be continuous. In one implementation,“selecting” comprises determining geometrical characteristics of the receive beam and/or geometrical characteristics of the transmit beam. The geometrical characteristics may notably include a beam direction. They may further include a beam width, for example.

Such a processing device can be flexibly applied. The processing device may for example operate within a transmit device or within a receive device. It can notably be operated in a base station or access point or in a user equipment (UE). The processing device may be operated in a transmit-receive point, e.g., of an access point or a base station or UE that can transmit and/or receive.

In an exemplary implementation form of the processing device, the beam pair selection is based on signal measurements of one or more interfering beams at the receive device.

A beam pair can be selected based only on the set of HRIBs. However, other interfering beams than the HRIBs may be considered for beam pair selection. This provides the advantage that the beam pair selection can be accurately performed since detailed information about the interfering beams is available.

In an exemplary implementation form of the processing device, the processing device is configured to select the beam pair from the set of candidate beam pairs (i ) based on: determining for each of the candidate beam pairs a score SCR(i,j ) based on the set of HRIBs; and selecting, from the set of candidate beam pairs, a beam pair that has obtained a highest score.

This provides the advantage that a specific quantity, i.e. the score SCR(i,j ) can be efficiently determined for beam selection. Hence, beam selection can be easily and efficiently performed by the processing device.

In an exemplary implementation form of the processing device, the processing device is configured to determine for each of the candidate beam pairs (i, ) the respective score SCR(i,j ) based further on the following: a signal strength descriptor of the respective candidate beam pair; and one or more signal strength descriptors of one or more interfering beam pairs (i, k), each of the one or more interfering beam pairs comprising the receive beam ( of the respective candidate beam pair and one of the interfering transmit beams (/c).

A signal strength descriptor of a beam pair can be any kind of information that specifies or correlates with a stipulated, estimated, or measured signal strength of the signal received via the beam pair. The signal strength may, for example, be a signal-to-noise ratio (SNR).

This provides the advantage that the signal strength can be efficiently computed and beam selection can be efficiently processed.

In an exemplary implementation form of the processing device, the score SCR(i,j ) is defined as: where S _t denotes a signal strength of the beam pair formed of the ;-th transmit beam from the transmit device and the i-th receive beam of the receive device, l _{i k} denotes a signal strength of the beam pair formed of the /c-th interfering transmit beam and the i-th receive beam of the receive device,“Set of HRlBs” denotes the set of HRIBs, and s% denotes a noise variance.

The score defined in this manner can be computed with little effort and it can result in effective interference management.

In an exemplary implementation form of the processing device, the processing device is configured to distinguish between interfering transmit beams of interfering transmit devices and transmit beams of the serving transmit device based on transmit device specific pilot signals.

This provides the advantage that such transmit device-specific pilot signals allow an easy separation between interference and serving signals at the Rx device.

According to a fourth aspect, the invention relates to a Transmit-Receive Point, TRP, in particular a serving TRP, in particular a base station, configured to: request, from an interfering transmit device, in particular from the TRP according to the second aspect or any of its implementation forms, information which identifies a set of high risk interfering beams, HRIBs, wherein the information is based on statistics of a usage of the one or more interfering beams by the interfering transmit device, receive the information about the set of HRIBs from the interfering transmit device, and forward the information about the set of HRIBs to another TRP.

The use of the HRIBs enables an interference management scheme with a reduced signalling overhead and rate compared to prior techniques. In addition, no interference measurements are required at the interfering Tx device and furthermore, the information of the set of HRIBs can be easily distributed among neighbouring TRPs or TRPs located close to the interfering transmit device.

The TRP may request the indication of the set of HRIBs for a group of resource blocks. The group may comprise one or more resource blocks. The TRP may be configured to receive from the interfering transmit device information which identifies the HRIBs for a group of resource blocks.

In an exemplary implementation form of the TRP, the TRP is configured to: receive from the interfering transmit device information which identifies the HRIBs for a group of resource blocks, forward the information which identifies the set of HRIBs or at least a subset of the HRIBs for the group of resource blocks to a second TRP, in particular a user equipment, in order to enable the second TRP to select a beam pair based on the set of HRIBs, and communicate with the second TRP via the selected beam pair.

The transmit-receive point can select which HRIBs to signal to the second transmit- receive point, i.e. the transmit-receive point might not necessarily forward all the HRIBs (and just a subset of the HRIBs) to the second transmit-receive point.

In an exemplary implementation form of the TRP, the TRP is configured to indicate whether the set of HRIBs is to be determined for an uplink transmission or for a downlink transmission.

The interfering Tx device can narrow down the selection of the set of HRIBs based on this information, i.e. distinguish between the interfering Tx beams for a TRP in the uplink (located at a specific point in the cell) or the interfering Tx beams for a UE in the downlink (located in the cell).

In an exemplary implementation form of the TRP, the TRP is configured to transmit information to the interfering transmit device for determining a potential interference impact of one or more interfering beams of the interfering transmit device.

This feature specifies some signaling from the victim cell to the interfering Tx device, such that the interfering Tx device has more information for determining the interference impact, which is used to determine the HRIBs. This information may include long-term (averaged over many UEs and resources) interference values, set of beams with a high interference, geographical location of the UEs.

According to a fifth aspect, the invention relates to a method for interference-aware beam selection, the method comprising: determining a set of high risk interfering beams, HRIBs, among a set of one or more interfering beams, wherein the set of HRIBs is determined based on statistics of a usage of the one or more interfering beams; and selecting a beam pair from a set of candidate beam pairs (i ), for setting up a communication link from a serving transmit device to a receive device via the selected beam pair, wherein each of the candidate beam pairs (i ) comprises a transmit beam (/) of the serving transmit device and a receive beam (i) of the receive device, wherein the selection is based on the set of high risk interfering beams, HRIBs.

Such method provides the advantage that the use of the HRIBs enables an interference management scheme with a reduced signalling overhead and rate compared to prior techniques. In addition, no interference measurements are required at the interfering Tx device and furthermore, the interfering Tx device is not restricted to use a reported HRIB on a given group of resource blocks.

A beam transmitted by a device other than the serving transmit device and the receive device is referred to herein as an interfering beam, regardless of whether or not the interfering beam is actually received by the receive device.

The statistics may include probabilities of employing the one or more interfering beams based on past usage and/or expected usage of the one or more interfering beams.

Each beam may provide a group of one or more resource blocks, or several groups of resource blocks. A resource block is a block in the time-frequency domain. It is also understood that each of the operations involving beams described herein may be performed for a certain group of one or more resource blocks.

The statistics may be based on past usage and/or expected usage of the one or more interfering beams.

The set of HRIBs may be determined for a group of resource blocks.

The set of HRIBs may be determined based on one or more potential interference impact values of the one or more interfering beams. The potential interference impact values may be based on the environment, e.g., the location of a victim cell with respect to the interfering Tx device that emits the interfering beams. The potential interference impact values can be based further on feedback from a victim device, regarding the interfering beams that would have a high interference impact at the victim device.

The beam pair selection may be further based on signal measurements of one or more interfering beams at the receive device.

In principle a beam pair can be selected based only on the set of HRIBs. However, other interfering beams than the HRIBs may be used for beam pair selection.

The set of HRIBs may be determined for an uplink transmission or a downlink

transmission.

The interfering Tx device can narrow down the selection of the set of HRIBs based on this information, i.e. distinguish between the interfering Tx beams for a TRP in the uplink (located at a specific point in the cell) or the interfering Tx beams for a UE in the downlink (located in the cell).

BRIEF DESCRIPTION OF THE DRAWINGS

Further embodiments of the invention will be described with respect to the following figures, in which:

Fig. 1 shows a schematic diagram illustrating beamformed communication in an interference scenario in which an aggressor cell 101 interferes a victim cell 102;

Fig. 2 shows a schematic diagram illustrating an example for determining High Risk Interfering Beams (HRIBs) for downlink transmission in victim cell 102;

Fig. 3 shows a flow chart of a first embodiment of an interference management scheme applied to TRP-UE interference; Fig. 4 shows a flow chart of a second embodiment of the interference management scheme applied to TRP-UE interference;

Fig. 5 shows a flow chart of an embodiment of the interference management scheme applied to TRP-TRP interference;

Fig. 6 shows a flow chart of an embodiment of the interference management scheme applied to UE-TRP interference;

Fig. 7 shows a flow chart of an embodiment of the interference management scheme applied to UE-UE interference;

Fig. 8 shows a signaling chart of an embodiment of the interference management scheme applied to TRP-UE interference;

Fig. 9 shows a signaling chart of an embodiment of the interference management scheme applied to TRP-TRP interference;

Fig. 10 shows a signaling chart of an embodiment of the interference management scheme applied to UE-TRP interference;

Fig. 1 1 shows a signaling chart of an embodiment of the interference management scheme applied to UE-UE interference; and

Fig. 12 shows a block diagram of an exemplary method 1200 for interference-aware beam selection.

DETAILED DESCRIPTION OF EMBODIMENTS

In the following detailed description, reference is made to the accompanying drawings, which form a part thereof, and in which is shown by way of illustration specific aspects in which the disclosure may be practiced. It is understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims.

It is understood that comments made in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if a specific method step is described, a corresponding device may include a unit to perform the described method step, even if such unit is not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary aspects described herein may be combined with each other, unless specifically noted otherwise.

The methods and devices described herein may also be implemented in wireless communication networks based on mobile communication standards similar to, e.g.,LTE, in particular 4.5G, 5G NR and beyond. The methods and devices described herein may also be implemented in wireless communication networks, in particular communication networks similar to WiFi communication standards according to IEEE 802.1 1. The described devices may include integrated circuits and/or passives and may be

manufactured according to various technologies. For example, the circuits may be designed as logic integrated circuits, analog integrated circuits, mixed signal integrated circuits, optical circuits, memory circuits and/or integrated passives.

The devices described herein may be configured to transmit and/or receive radio signals. Radio signals may be or may include radio frequency signals radiated by a radio transmitting device (or radio transmitter or sender).

The devices and systems described herein may include processors, memories and transceivers, i.e. transmitters and/or receivers. In the following description, the term “processor” or“processing device” describes any device that can be utilized for processing specific tasks (or blocks or steps). A processor or processing device can be a single processor or a multi-core processor or can include a set of processors or can include means for processing. A processor or processing device can process software or firmware or applications etc. In the following, base stations and User Equipments are described. Examples of a base station may include access nodes, evolved NodeBs (eNBs), gNBs, NodeBs, master eNBs (MeNBs), secondary eNBs (SeNBs), remote radio heads and access points.

Fig. 1 shows a schematic diagram illustrating beamformed communication in an interference scenario in which an aggressor cell 101 interferes a victim cell 102.

The serving TRP 120 in Fig. 1 can set up a transmission to UE 1 , 140 in the victim cell 102, if the serving TRP 120 (serving Tx device) transmits with Tx beam #3 and UE 1 , 140 (interfered Rx device) receives with Rx beam #4. Although the transmission with this beam pair link can have a high SNR, the transmission with this beam pair link can result in a low SINR if the interfering TRP 1 10 (interfering Tx device) in the aggressor cell 101 transmits with Tx beam #9, 1 12, for example to transmit to UE 2, 130 in the aggressor cell 101 .

The interference from interfering Tx device 1 10 can be avoided if the Rx device 140 selects another beam pair for its transmission, assuming the Rx device 140 is aware of the Tx beams 1 12 that the interfering Tx device(s) 1 10 will use. Nonetheless, the Rx device 140 is generally unaware of the Tx beams 1 12 that the interfering Tx device(s) 1 10 will use. The interference management scheme as presented in this disclosure can be used to provide the Rx device 140 with sufficient information about the Tx beams 1 12 that the interfering Tx device(s) 1 10 may use in order to enable the Rx device 140 to select other beam pairs for its transmission, hence resulting in improved beamformed communication.

In the following it is elaborated in detail how the HRIBs are determined at the interfering Tx device 1 10 and afterwards how the HRIBs are employed at the interfered Rx device 140, e.g., for a TRP or UE in the victim cell 102.

Fig. 2 shows a schematic diagram illustrating an example for determining High Risk Interfering Beams (HRIBs) for downlink transmission in victim cell 102.

The HRIBs 206 can be determined at the interfering Tx device 1 10 based on the statistics of a usage 203 of the Tx beams 1 1 1 of the interfering Tx device 1 10, in particular on a group of resource blocks. In addition, the HRIBs 206 can be determined also considering the potential interference impact 204 of the Tx beams 1 1 1 of the interfering Tx device 1 10 at the interfered Rx device (e.g., UE 1 , 140 as shown in Fig. 1 ). The statistics of a usage 203 of the Tx beams 1 1 1 of the interfering Tx device 1 10 on a group of resource blocks can be determined at the interfering Tx device 1 10 based on past usage of the Tx beam 1 1 1 by the interfering Tx device 1 10 on the group of resource blocks and/or based on expected usage of the Tx beams 1 1 1 by the interfering Tx device 1 10 on the group of resource blocks, e.g., by considering predefined scheduling decisions or prediction capabilities (e.g., for UE tracking) of the interfering Tx device 1 10. For example, a TRP can determine the probability of using a Tx beam on a group of resource blocks, based on the number of times the TRP has used the Tx beam on the given group of resource blocks over a certain time window, e.g., for past transmissions to UEs in its cell.

For instance in Fig. 2, based on past transmission to UE 2, 130 on a given group of resource blocks, the probability for the interfering TRP 1 10 in the aggressor cell 101 to use Tx beams #6, 7, 8 and 9 on the given group of resource blocks is high. The probability of using a Tx beam depends on the spatial distribution of the Rx devices to which the interfering Tx device 1 10 is transmitting to, e.g., the distribution of the UEs 130 in the aggressor cell 101 . Since the distribution of these Rx devices 130 is usually not static and can change over time, the probability of using a Tx beam is time-dependent. For example, some Tx beams of a TRP in a cell may be employed more often depending on the current UE distribution in a cell, where the UE distribution can depend on the time of the day.

The potential interference impact of a Tx beam from an interfering Tx device 1 10 at the interfered Rx device (e.g., UE 1 , 140 shown in Fig. 1 or Serving TRP 120) can be determined at the interfering Tx device 1 10 based on the possible transmit power and elevation of the Tx beam 1 1 1 , as well as based on environment information depending on the location of the interfered Rx device 140, 120. The potential interference impact of a Tx beam 1 1 1 based on environment information depending on the location of the interfered Rx device 140, 120 can be obtained based on whether the interfered Rx device 140, 120 is receiving a downlink or an uplink transmission, i.e. whether the interfered Rx device 140, 120 is a UE 140 or a TRP 120 in the victim cell 102 receiving a downlink or an uplink transmission, respectively. For example, based on the location of the victim cell 102 with respect to the interfering Tx device 1 10, the interfering Tx device 1 10 can determine which of its Tx beams 1 1 1 can have a higher potential interference impact for a downlink transmission in the victim cell 102, or which of its Tx beams 1 1 1 can have a higher potential interference impact for an uplink transmission in the victim cell 102. For example, the Tx beams #7, 8, 9 and 10 of the interfering TRP 1 10 in Fig. 2 can have a high potential interference impact 204 for a downlink transmission in the victim cell 102, in particular for UEs near the cell edge of the victim cell 102.

The HRIBs 206 of an interfering Tx device 1 10 for a group of resource blocks can be determined at the interfering TRP 1 10 as those Tx beams 201 of the interfering Tx device 1 10 which have a high beam usage probability 203 on the group of resource blocks (e.g., based on past or expected usage of the Tx beams 1 1 1 ). In this case, the HRIBs 206 can be specific to the interfering Tx device 1 10 and the group of resource blocks.

The HRIBs 206 can also be determined as those Tx beams 201 , 202 of the interfering Tx device 1 10 which have a high beam usage probability 203 on the group of resource blocks (e.g., based on past or expected usage of the Tx beams) and which have a high potential interference impact 204 at the interfered Rx device 140 (e.g., based on whether the interfered Rx device 140 is receiving a downlink or an uplink transmission) as shown in Fig. 2. In this case, the HRIBs 206 can be specific to the interfering Tx device 1 10, the group of resource blocks, to the victim cell 102 and to whether the interfered Rx device 140, 120 in the victim cell is receiving a downlink or an uplink transmission. In the example shown on Fig. 2, the HRIBs 206 would correspond to Tx beams #7, 8 and 9.

The interfering Tx device 1 10 is not restricted to use any of the Tx beams 1 1 1 which are determined and signalled as HRIBs 206 on a given group of resource blocks.

After determining 205 the HRIBs 206 at the interfering Tx device 1 10, the interfering Tx device 1 10 signals the HRIBs 206 on a group of resource blocks to the serving TRP 120 in the victim cell 102. If the serving TRP 120 is the interfered Rx device, it can make use of the HRIBs 206 when selecting a beam pair link, in particular an Rx beam, for an uplink transmission. For example, if the serving TRP 120 would like to use an Rx beam but determines, based on interference measurements, that with this Rx beam it could receive interference from an interfering Tx beam in the set of HRIBs 206, the serving TRP 120 can decide to use instead another Rx beam to avoid the potential interference.

If the interfered Rx device is a UE in the victim cell 102 (e.g., UE 1 , 140), the serving TRP 120 can decide which of the received HRIBs 206 to send to the UE 140, such that the UE can perform interference management. For example, if the serving TRP 120 in the victim cell 102 has information about the location of the UE 140, it can select to send only a subset of the HRIBs 206 of an interfering TRP 1 10 to reduce the signaling overhead. The serving TRP 120 in the victim cell 102 can also realize that for a given UE there are no relevant HRIBs 206 on a group of resource and can make use of this information to schedule the UE on the group of resource blocks (without signaling any HRIBs 206 to the UE), as it can expect that the UE would not receive interference from the interfering TRP 1 10. If HRIBs 206 are signaled to the UE, it can make use of the HRIBs 206 when selecting a beam pair link, in particular a Rx beam, for a downlink transmission from the serving TRP 120. For example, if the UE would like to use a Rx beam but determines, based on interference measurements, that with this Rx beam it can receive interference from an interfering Tx beam in the set of HRIBs 206, the UE 140 can decide to use instead another Rx beam to avoid the potential interference. Consider for instance the example in Fig. 1 , where UE 1 , 140 can select Rx beam #7 instead of Rx beam #4 to avoid potential interference from the interfering Tx device 1 10, if Tx beam #9 of the interfering TRP 1 10 in the aggressor cell is signaled as a HRIB 206 to the UE 140.

For exploiting the HRIBs 206 at the interfered Rx device 140, interference measurements can be used at the interfered Rx device 140. To obtain the interference measurements, the interfered Rx device 140 can employ different pilot/reference/sounding signals of the interfering Tx device 1 10, such as the synchronization signal block (SSB) or CSI-RS (channel state information reference signal) in the aggressor cell 101 , if the interfering Tx device 1 10 is an interfering TRP. SSB, which is cell specific, has already been agreed to be used for neighbor cell reporting in 5G NR. CSI-RS, which is UE specific, can also be used to obtain interference measurements. For example, the CSI-RS assigned to a UE (e.g., UE 2, 130) which is connected to the interfering TRP 1 10 in the aggressor cell 101 , e.g., near the cell edge of the victim cell 102, may be used for interference measurements at the interfered Rx device 140 in the victim cell 102. For this, the interfering TRP 1 10 may share the CSI-RS configuration with the serving TRP 120 of the victim cell 102. If the interfered Rx device is a UE (e.g., UE 1 , 140), the serving TRP 120 can forward the CSI-RS configuration of the interfering TRP 1 10 to the UE 140 in the victim cell 102. Note that the interfered UE 140 is not connected to the interfering TRP 1 10.

On the other hand, if the interfering Tx device 1 10 in the aggressor cell 101 is an interfering UE (e.g., UE 2, 130), which is connected to the interfering TRP 1 10 in the aggressor cell 101 , SRS used by the interfering UE 130 can be used for obtaining interference measurements at the interfered Rx device 140 in the victim cell 102. For this purpose, the interfering TRP 1 10 may share the SRS configuration with the serving TRP 120 of the victim cell 102. If the interfered Rx device is a UE (e.g., UE 1 , 140), the serving TRP 120 may forward the SRS configuration to the interfered UE 140 in the victim cell 102.

For exploiting the HRIBs 206, the Tx beams 1 1 1 of the interfering Tx device 1 10 may be identified. However, the Tx beam 1 1 1 may not be explicitly described in the standard. Nevertheless, the Tx beam 1 1 1 of an interfering Tx device 1 10 can be identified via the index of the signaling field or the indicator of the resource, where the interfering Tx device 1 10 sent a pilot/reference/sounding signal with the Tx beam 1 1 1 . Depending on the signal used for the interference measurements at the interfered Rx device 140 in the victim cell 102, the Tx beam 1 1 1 of the interfering Tx device 1 10 can be identified, e.g., via Synchronization Signal Block (SSB) index, the CSI-RS resource indicator or the SRS resource indicator. Thus, when mentioning Tx beam or Tx beam index in this description, it actually refers to an identifier of the Tx beam, which is mapped to the resource indicator corresponding to that Tx beam.

The use of the HRIBs 206 enables an efficient interference management scheme with a reduced signalling overhead and rate compared to prior techniques. In addition, no interference measurements are required at the interfering Tx device 1 10 and furthermore, the interfering Tx device 1 10 is not restricted to use a reported HRIB 206 on a given group of resource blocks.

Based on the above description, various embodiments of transmit devices and receive devices of UEs and TRPs together with corresponding processing devices can be implemented. In the following exemplary representations of such devices are described.

A first processing device, in particular a processing device of a first T ransmit-Receive Point, TRP, e.g., an interfering TRP 1 10, may be used for determining 205 a set of high risk interfering beams, HRIBs 206. The first processing device is configured to determine a set of HRIBs 206 among a set of one or more interfering beams 201 , 202, wherein the set of HRIBs 206 is determined based on statistics of a usage 203 of the one or more interfering beams 201 , 202. The statistics 203 may be based on past usage and/or expected usage of the one or more interfering beams 201 . The set of HRIBs 206 may be determined for a group of resource blocks. The set of HRIBs 206 may be determined based further on one or more potential interference impact values 204 of the one or more interfering beams 201 , 202, e.g., as exemplarily shown in the two tables at the bottom of Fig. 2. In this example, TX beam #6 has a beam usage probability of 24%, TX beam #7 has a beam usage probability of 32%, TX beam #8 has a beam usage probability of 18% and TX beam #9 has a beam usage probability of 26% while the other TX beams #1 to #5 and #10 have each a beam usage probability of 0%. Thus, the HRIBs 206 are selected from these TX beams #6 to #9. Further, the selection may be based on potential interference impact 204 for DL in victim cell. In this example, TX beams #7 to #10 have a high potential interference impact while the other TX beams #1 to #6 have a low potential interference impact. Thus, the HRIBs 206 may be selected from these TX beams #7 to #10. Considering both conditions, the HRIBs 206 are selected from TX beams #7 to #9 as shown in the table at the bottom of Fig. 2.

The set of HRIBs 206 may be determined for an uplink transmission or for a downlink transmission.

A first TRP 1 10, in particular an interfering transmit device as shown in Fig. 2, includes the first processing device described above. The first TRP 1 10 is configured to generate one or more transmit beams 201 , 1 1 1 and to provide statistics of a usage 203 of the one or more transmit beams 201 , 1 1 1 . The first TRP may be configured to transmit the set of HRIBs 206 to another TRP, 120 in particular to another base station. The first TRP 1 10 may be configured to transmit a configuration of a pilot signal to another TRP, 120.

A second processing device, in particular a processing device of a second Transmit- Receive Point, TRP, in particular a UE, 140, for beam pair selection, is configured to select a beam pair from a set of candidate beam pairs for setting up a communication link from a serving transmit device 120 to a receive device 140 via the selected beam pair, wherein each of the candidate beam pairs (i ) comprises a transmit beam (/) of the serving transmit device 120 and a receive beam (i) of the receive device 140, wherein the selection is based on a set of high risk interfering beams, HRIBs 206, in particular a set of HRIBs 206 determined by the first processing device described above. Such a second TRP may be a serving TRP 120 or alternatively a UE 140 in the victim cell. The beam pair selection may be based on signal measurements of one or more interfering beams 1 12 at the receive device, e.g., at UE 1 , 140. The second processing device may be configured to select the beam pair from the set of candidate beam pairs (i ) based on: determining for each of the candidate beam pairs (i ) a score SCR(i,j ) based on the set of HRIBs 206; and selecting, from the set of candidate beam pairs (i ), a beam pair that has obtained a highest score.

The second processing device may be configured to determine for each of the candidate beam pairs (i ) the respective score SCR(i,j ) based further on the following: a signal strength descriptor of the respective candidate beam pair (i ) ; and one or more signal strength descriptors of one or more interfering beam pairs, each of the one or more interfering beam pairs comprising the receive beam (i) of the respective candidate beam pair (i ) and one of the interfering transmit beams 1 1 1 . The second processing device may be configured to distinguish between interfering transmit beams of interfering transmit devices 1 10 and transmit beams of the serving transmit device 120 based on transmit device-specific pilot signals.

A third Transmit-Receive Point, TRP 120, in particular a serving TRP, in particular a base station, is configured to: request, from an interfering transmit device 1 10, in particular from the first TRP as described above, information which identifies a set of high risk interfering beams, HRIBs 206, wherein the information is based on statistics of a usage 203 of the one or more interfering beams 201 , 202 by the interfering transmit device 1 10, receive the information about the set of HRIBs 206 from the interfering transmit device 1 10, and forward the information about the set of HRIBs 206 to another TRP, in particular a UE 140.

The third TRP 120 may be configured to: receive from the interfering transmit device 1 10 information which identifies the HRIBs 206 for a group of resource blocks, forward the information which identifies the set of HRIBs 206 or at least a subset of the HRIBs for the group of resource blocks to a second TRP, in particular a user equipment 140, in order to enable the second TRP to select a beam pair based on the set of HRIBs 206, and communicate with the second TRP via the selected beam pair.

The third TRP 120 may be configured to indicate whether the set of HRIBs 206 is to be determined for an uplink transmission or for a downlink transmission. The third TRP 120 may be configured to transmit information to the interfering transmit device 1 10 for determining a potential interference impact 204 of one or more interfering beams 202 of the interfering transmit device 1 10.

Depending on whether the interfering Tx device is a TRP (e.g., interfering TRP 1 10) or a UE (e.g., UE 2, 130) in the aggressor cell 101 and whether the interfered Rx device is a TRP (e.g., serving TRP 120) or a UE (e.g., UE 1 , 140) in the victim cell 102, different types of interference can exist, namely: TRP-UE interference, TRP-TRP interference, UE-TRP interference and UE-UE interference. In the following several embodiments of the disclosed interference management technique are presented with respect to Figures 3 to 1 1 for these different types of interference.

Fig. 3 shows a flow chart of a first embodiment of the efficient interference management scheme applied to TRP-UE interference. The flow chart shows the case of TRP-UE interference, i.e. where UE C (e.g., corresponding to UE1 , 140 depicted in Fig. 1 ), being served by serving TRP A (e.g., corresponding to Serving TRP 120 depicted in Fig. 2), can be potentially interfered by TRP B (e.g., corresponding to Interfering TRP 1 10 depicted in Fig. 2). For this embodiment, the HRIBs may be determined at TRP B based on a beam usage probability of the Tx beams of the interfering TRP B on a group of resource blocks. In this case, the set of HRIBs corresponds to the set of Tx beams which have a beam usage probability higher than a threshold. The HRIBs are sent to the serving TRP A, which then selects which HRIBs to send to UE C. Afterwards the selected HRIBs are sent to UE C, which then performs the beam pair selection based on the interference measurements and considering the signaled HRIBs 206, e.g., as described above with respect to Fig. 2.

Fig. 4 shows a flow chart of a second embodiment of the efficient interference

management scheme applied to TRP-UE interference. The flow chart shows the case of TRP-UE interference, i.e. where UE C (e.g., corresponding to UE1 , 140 depicted in Fig.

1 ), being served by serving TRP A (e.g., corresponding to Serving TRP 120 depicted in Fig. 2), can be potentially interfered by TRP B (e.g., corresponding to Interfering TRP 1 10 depicted in Fig. 2). For this embodiment, the HRIBs may be determined at TRP B based on a beam usage probability of the Tx beams of the interfering TRP B on a group of resource blocks and on the potential interference impact of the Tx beams of the interfering TRP B on a downlink transmission by the serving TRP A. In this case, the set of HRIBs correspond to the set of Tx beams which have a beam usage probability higher than a probability threshold and a potential interference impact above an interference threshold. The HRIBs are sent to the serving TRP A, which then selects which HRIBs to send to UE C. Afterwards, the selected HRIBs are sent to UE C, which then performs the beam pair selection based on the interference measurements and considering the signaled HRIBs 206, e.g., as described above with respect to Fig. 2.

Fig. 5 shows a flow chart of an embodiment of the efficient interference management scheme applied to TRP-TRP interference. The flow chart shows the case of TRP-TRP interference, i.e. where TRP A (e.g., corresponding to Serving TRP 120 depicted in Fig. 2) can be potentially interfered by TRP B (e.g., corresponding to Interfering TRP 1 10 depicted in Fig. 2). For this embodiment, the HRIBs may be determined at TRP B based on a beam usage probability of the Tx beams of the interfering TRP 6 on a group of resource blocks and on the potential interference impact of the Tx beams of the interfering TRP B on a uplink transmission received at TRP A. In this case, the set of HRIBs correspond to the set of Tx beams which have a beam usage probability higher than a probability threshold and a potential interference impact above an interference threshold. The HRIBs are sent to the serving TRP A, which then performs the beam pair selection based on the interference measurements and considering the signaled HRIBs 206, e.g., as described above with respect to Fig. 2.

Fig. 6 shows a flow chart of an embodiment of the efficient interference management scheme applied to UE-TRP interference. The flow chart shows the case of UE-TRP interference, i.e. where the TRP A (e.g., corresponding to Serving TRP 120 depicted in Fig. 2) can be potentially interfered by UE B (e.g., corresponding to UE2, 130 depicted in Fig. 2), which is being served by TRP D (e.g., corresponding to Interfering TRP 1 10 depicted in Fig. 2). For this embodiment, the HRIBs may be determined at UE B based on a beam usage probability of the Tx beams of the interfering UE B on a group of resource blocks and on the potential interference impact of the Tx beams of the interfering UE B on a uplink transmission received at TRP A. In this case, the set of HRIBs correspond to the set of Tx beams which have a beam usage probability higher than a probability threshold and a potential interference impact above an interference threshold. The HRIBs are sent to the serving TRP D of UE B, which then sends the HRIBs to TRP A. After receiving the HRIBs, TRP A performs the beam pair selection based on the interference measurements and considering the signaled HRIBs 206, e.g., as described above with respect to Fig. 2. Fig. 7 shows a flow chart of an embodiment of the interference management scheme applied to UE-UE interference. The flow chart shows the case of UE-UE interference, i.e. where UE C (e.g., corresponding to UE1 , 140 depicted in Fig. 1 ), which is being served by TRP A (e.g., corresponding to Serving TRP 120 depicted in Fig. 2), can be potentially interfered by UE B (e.g., corresponding to UE2, 130 depicted in Fig. 2), which is being served by TRP D (e.g., corresponding to Interfering TRP 1 10 depicted in Fig. 2). For this embodiment, the HRIBs may be determined at UE B based on a beam usage probability of the Tx beams of the interfering UE B on a group of resource blocks and on the potential interference impact of the Tx beams of the interfering UE B on a downlink transmission from the serving TRP A. In this case, the set of HRIBs correspond to the set of Tx beams which have a beam usage probability higher than a probability threshold and a potential interference impact above an interference threshold. The HRIBs are sent to the serving TRP D of UE B, which then sends the HRIBs to TRP A. The serving TRP D can also select which HRIBs to send to the serving TRP A. After receiving the HRIBs, TRP A selects which HRIBs to send to UE C. Afterwards the selected HRIBs are sent to UE C, which then performs the beam pair selection based on the interference measurements and considering the signaled HRIBs 206, e.g., as described above with respect to Fig. 2.

Fig. 8 shows a signaling chart of an embodiment of the interference management scheme applied to TRP-UE interference. The signaling chart shows the case of TRP-UE interference, i.e. where an interfering TRP (e.g., interfering TRP 1 10 in Fig. 2) in the aggressor cell 101 can interfere with a UE (e.g., UE1 , 140 shown in Fig. 1 ) in the victim cell 102. The TRP 120 in the victim cell 102 requests HRIBs for a DL transmission on a group of resource blocks to the interfering TRP 1 10 in the aggressor cell 102. After receiving the HRIBs, the TRP 120 in the victim cell 102 selects which HRIBs to send to the UE 140 in the victim cell 102. The signaling of the pilot signal of the interfering TRP 1 10 for enabling interference measurements at the UE 140 in the victim cell 102 is also shown. The beam pair selection is then performed at the UE 140 in the victim cell 102 based on the interference measurements and considering the HRIBs 206, e.g., as described above with respect to Fig. 2.

Fig. 9 shows a signaling chart of an embodiment of the interference management scheme applied to TRP-TRP interference. The signaling chart shows the case of TRP-TRP interference, i.e. where an interfering TRP (e.g., interfering TRP 1 10 in Fig. 2) in the aggressor cell 101 can interfere with a TRP (e.g., serving TRP 120 in Fig. 2) in the victim cell 102. The TRP 120 in the victim cell 102 requests HRIBs for an UL transmission on a group of resource blocks to the interfering TRP 1 10 in the aggressor cell 101. The signaling of the pilot signal of the interfering TRP 1 10 for enabling interference

measurements at the TRP 120 in the victim cell 102 is also shown. The beam pair selection is then performed at the TRP 120 in the victim cell 102 based on the interference measurements and considering the HRIBs 206, e.g., as described above with respect to Fig. 2.

Fig. 10 shows a signaling chart of an embodiment of the interference management scheme applied to UE-TRP interference. The signaling chart shows the case of UE-TRP interference, i.e. where an interfering UE (e.g., corresponding to UE2, 130 depicted in Fig. 2) in the aggressor cell 101 can interfere with a TRP (e.g., corresponding to serving TRP 120 depicted in Fig. 2) in the victim cell 102. The TRP 120 in the victim cell 102 requests HRIBs 206 for an UL transmission on a group of resource blocks to the interfering TRP 1 10 in the aggressor cell 101 , which then requests the HRIBs 206 to the interfering UE 130 in the aggressor cell 101 . The UE 130 in the aggressor cell 101 determines the HRIBs 206 and then sends them to the TRP 1 10 in the aggressor cell 101 , which then sends the HRIBs 206 to the TRP 120 in the victim cell 102. The TRP 1 10 in the aggressor cell 101 can select which HRIBs 206 to send to the TRP 120 in the victim cell 102. The signaling of the pilot signal of the interfering TRP 1 10 for enabling interference

measurements at the TRP 120 in the victim cell 102 is also shown. The beam pair selection is then performed at the TRP 120 in the victim cell 102 based on the interference measurements and considering the HRIBs 206.

Fig. 1 1 shows a signaling chart of an embodiment of the interference management scheme applied to UE-UE interference. The signaling chart shows the case of UE-UE interference, i.e. where an interfering UE (e.g., corresponding to UE2, 130 depicted in Fig. 2) in the aggressor cell 101 can interfere with a UE (e.g., UE1 , 140 shown in Fig. 1 ) in the victim cell 102. The TRP 120 in the victim cell 102 requests HRIBs 206 for a DL transmission on a group of resource blocks to the interfering TRP 1 10 in the aggressor cell 101 , which then requests the HRIBs 206 to the interfering UE 130 in the aggressor cell 101 . The UE 130 in the aggressor cell 101 determines the HRIBs 206, e.g., as shown above with respect to Fig. 2, and then sends them to the TRP 1 10 in the aggressor cell 101 , which then sends the HRIBs 206 to the TRP 120 in the victim cell 102. The TRP 1 10 in the aggressor cell 101 can select which HRIBs 206 to send to the TRP 120 in the victim cell 102. After receiving the HRIBs 206, the TRP 120 in the victim cell 102 selects which HRIBs 206 to send to the UE (e.g., corresponding to UE1 , 140 depicted in Fig. 1 ) in the victim cell 102. The signaling of the pilot signal of the interfering TRP 1 10 for enabling interference measurements at the UE 140 in the victim cell 102 is also shown. The beam pair selection is then performed at the UE 140 in the victim cell 102 based on the interference measurements and considering the HRIBs 206, e.g., as described above with respect to Fig. 2.

Fig. 12 shows a block diagram of an exemplary method 1200 for interference aware beam selection. The method 1200 includes determining 1201 a set of high risk interfering beams, HRIBs 206, among a set of one or more interfering beams 201 , wherein the set of HRIBs 206 is determined based on statistics of a usage (203) of the one or more interfering beams 201 , e.g., as described above with respect to Fig. 2. The method 1200 further includes selecting a beam pair from a set of candidate beam pairs (i, ), for setting up a communication link from a serving transmit device 120 to a receive device 140, e.g., as described above with respect to Fig. 2, via the selected beam pair, wherein each of the candidate beam pairs (i, ) comprises a transmit beam (/) of the serving transmit device 120 and a receive beam (i) of the receive device 140, wherein the selection is based on the set of high risk interfering beams, HRIBs 206.

The present disclosure also supports a computer program product including computer executable code or computer executable instructions that, when executed, causes at least one computer to execute the performing and computing steps described herein, in particular the steps of the method described above. Such a computer program product may include a readable non-transitory storage medium storing program code thereon for use by a computer. The program code may perform the processing and computing steps described herein, in particular the method described above.

While a particular feature or aspect of the disclosure may have been disclosed with respect to only one of several implementations, such feature or aspect may be combined with one or more other features or aspects of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms "include", "have", "with", or other variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term "comprise". Also, the terms "exemplary", "for example" and "e.g." are merely meant as an example, rather than the best or optimal. The terms“coupled” and “connected”, along with derivatives may have been used. It should be understood that these terms may have been used to indicate that two elements cooperate or interact with each other regardless whether they are in direct physical or electrical contact, or they are not in direct contact with each other.

Although specific aspects have been illustrated and described herein, it will be

appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific aspects shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific aspects discussed herein.

Although the elements in the following claims are recited in a particular sequence with corresponding labeling, unless the claim recitations otherwise imply a particular sequence for implementing some or all of those elements, those elements are not necessarily intended to be limited to being implemented in that particular sequence.

Many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the above teachings. Of course, those skilled in the art readily recognize that there are numerous applications of the invention beyond those described herein. While the present invention has been described with reference to one or more particular embodiments, those skilled in the art recognize that many changes may be made thereto without departing from the scope of the present invention. It is therefore to be understood that within the scope of the appended claims and their equivalents, the invention may be practiced otherwise than as specifically described herein.