Antenna panel selection for a user equipment

Abstract

There is provided techniques for selecting antenna panel in a user equipment. A method is performed by the user equipment. The user equipment comprises at least two antenna panels. The method comprises obtaining measurements on downlink reference signals as received by the user equipment from a network node. The method comprises evaluating a performance metric for communicating with the network node. The performance metric is based on the measurements. One performance metric value of the performance metric is calculated per each of the antenna panels. The performance metric at least pertains to at least one of throughput and latency. The method comprises selecting, for communicating with the network node, the antenna panel having best performance metric value.

Description

[0001] ANTENNA PANEL SELECTION FOR A USER EQUIPMENT

[0002] TECHNICAL FIELD

[0003] Embodiments presented herein relate to a method, a user equipment, a computer program, and a computer program product for selecting antenna panel in the user equipment.

[0004] BACKGROUND

[0005] In general terms, reference signals can be used for different purposes in communication systems. For example, uplink reference signals, i.e., reference signals as transmitted by a user equipment (UE) at the user side to a network node at the network side, can be used for providing channel state information to the network in the uplink (i.e., in the direction from the UE to the network node). In some examples, the usage of uplink reference signals includes, e.g., deriving the appropriate transmission / reception beams and / or to perform link adaptation (i.e., setting the transmission rank and the modulation and coding scheme), and for selecting the appropriate precoder for downlink and uplink data transmissions.

[0006] Deriving the appropriate transmission / reception beams is generally referred to as beam management. Non-limiting examples where reference signals are used in the context of beam management will be disclosed next.

[0007] In some communications systems, multiple beams can be used to transmit and receive signals at the network node and the UE. As an example, for each downlink transmission beam at the network node, there is typically an associated uplink reception beam at the UE for receiving the signals sent in the downlink transmission beam. The downlink transmission beam and the associated uplink reception beam form a beam pair. Suitable beam pairs can be identified through a so-called beam management procedure.

[0008] Beam management can be performed based on downlink and / or uplink reference signals. Aspects where beam management is performed based on uplink reference signals, will be disclosed next. When a UE is triggered with an uplink reference signal-based uplink beam management procedure, the UE selects one antenna panel based on highest measured received power as measured on a downlink reference signal (e.g., as used as a quasi co location (QCL) source for the uplink reference signal resources in an uplink reference signal resource set for beam management). The UE then transmits a burst of uplink reference signal resources in different narrow beams from the selected antenna panel.

[0009] However, there is still a need for improved selection of antenna panels at the UE. SUMMARY

[0010] An object of embodiments herein is to provide improved selection of antenna panels at the UE, where the above issues are avoided, or at least have been mitigated or reduced.

[0011] For example, different antenna panels might have different number of transmit and / or receive chains, and / or experience different Power Management Maximum Power Reduction (P-MPR) events. Selecting the antenna panel based on highest measured received power might therefore result in that the best beam pair link with respect to, for example, uplink and / or downlink throughput for the UE is not identified during the uplink beam management procedure.

[0012] A particular object is to avoid the issues associated with selecting the antenna panel based on highest measured received power.

[0013] According to a first aspect there is presented a method for selecting antenna panel in a user equipment. The method is performed by the user equipment. The user equipment comprises at least two antenna panels. The method comprises obtaining measurements on downlink reference signals as received by the user equipment from a network node. The method comprises evaluating a performance metric for communicating with the network node. The performance metric is based on the measurements. One performance metric value of the performance metric is calculated per each of the antenna panels. The performance metric at least pertains to at least one of throughput and latency. The method comprises selecting, for communicating with the network node, the antenna panel having best performance metric value.

[0014] According to a second aspect there is presented a user equipment for antenna panel selection. The user equipment comprises at least two antenna panels. The user equipment further comprises processing circuitry. The processing circuitry is configured to cause the user equipment to obtain measurements on downlink reference signals as received by the user equipment from a network node. The processing circuitry is configured to cause the user equipment to evaluate a performance metric for communicating with the network node. The performance metric is based on the measurements. One performance metric value of the performance metric is calculated per each of the antenna panels. The performance metric at least pertains to at least one of throughput and latency. The processing circuitry is configured to cause the user equipment to select, for communicating with the network node, the antenna panel having best performance metric value. According to a third aspect there is presented a user equipment for antenna panel selection. The user equipment comprises at least two antenna panels. The user equipment further comprises an obtain module configured to obtain measurements on downlink reference signals as received by the user equipment from a network node. The user equipment further comprises an evaluate module configured to evaluate a performance metric for communicating with the network node. The performance metric is based on the measurements. One performance metric value of the performance metric is calculated per each of the antenna panels. The performance metric at least pertains to at least one of throughput and latency. The user equipment further comprises a select module configured to select, for communicating with the network node, the antenna panel having best performance metric value.

[0015] According to a fourth aspect there is presented a computer program for selecting antenna panel in a user equipment. The computer program comprises computer code which, when run on processing circuitry of a user equipment comprising at least two antenna panels, causes the user equipment to perform actions. One action comprises the user equipment to obtain measurements on downlink reference signals as received by the user equipment from a network node. One action comprises the user equipment to evaluate a performance metric for communicating with the network node. The performance metric is based on the measurements. One performance metric value of the performance metric is calculated per each of the antenna panels. The performance metric at least pertains to at least one of throughput and latency. One action comprises the user equipment to select, for communicating with the network node, the antenna panel having best performance metric value.

[0016] According to a fifth aspect there is presented a computer program product comprising a computer program according to the fourth aspect and a computer readable storage medium on which the computer program is stored. The computer readable storage medium could be a non-transitory computer readable storage medium.

[0017] Advantageously, these aspects provide selection of antenna panels at the UE where the above issues are avoided.

[0018] Advantageously, these aspects provide selection of antenna panels at the UE where the issues associated with selecting the antenna panel based on highest measured received power are avoided.

[0019] Advantageously, in the context of beam management, these aspects enable a beam pair link to be selected during an uplink reference signal-based beam management procedure not only based on received power, but also by taking other aspects, such as throughput and latency into account. In turn, this can improve the performance in both downlink and uplink for the UE. Other objectives, features and advantages of the enclosed embodiments will be apparent from the following detailed disclosure, from the attached dependent claims as well as from the drawings.

[0020] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a / an / the element, apparatus, component, means, module, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, module, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

[0021] BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The inventive concept is now described, by way of example, with reference to the accompanying drawings, in which:

[0023] Fig. 1 is a schematic diagram illustrating a communications network according to embodiments;

[0024] Fig. 2 is a block diagram of a user equipment according to an embodiment;

[0025] Fig. 3 is a flowchart of methods according to embodiments;

[0026] Fig. 4 is a signaling diagram of a method according to an embodiment;

[0027] Fig. 5 show simulation results according to an embodiment;

[0028] Fig. 6 is a schematic diagram showing structural units of a user equipment according to an embodiment;

[0029] Fig. 7 is a schematic diagram showing functional modules of a user equipment according to an embodiment; and

[0030] Fig. 8 shows one example of a computer program product comprising computer readable storage medium according to an embodiment.

[0031] DETAILED DESCRIPTION

[0032] The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the inventive concept are shown. This inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like elements throughout the description. Any step or feature illustrated by dashed lines should be regarded as optional.

[0033] Fig. 1 is a schematic diagram illustrating a communications network 100 where embodiments presented herein can be applied. The communications network 100 comprises at least one network node 110a, 110b, such as at least one (radio) access network node, radio base station, base transceiver station, node B (NB), evolved node B (eNB), gNB, access point, access node, integrated access and backhaul (IAB) node, transmission and reception point (TRP), etc. The at least one network node 110a, 110b is configured to provide coverage, and thus network access, to a UE 200 via uplink / downlink links 130a, 130b. The UE 200 might be any of a portable wireless device, mobile station, mobile phone, handset, wireless local loop phone, smartphone, laptop computer, tablet computer, wireless sensor device, Internet of Things device, network equipped vehicle, network equipped gaming control, etc. as long as the UE 200 is capable of implementing the herein disclosed embodiments.

[0034] Fig. 2 is a block diagram of a UE 200. The UE is illustrated as having three antenna panels 240a, 240b, 240c as connectable to a baseband unit 250 via transmit and / or receive chains 260a, 260b, 260c and a switching network 270. In this respect, antenna panel 240a is an antenna array with two columns and four rows of dual-polarized antenna elements, where the antenna elements of each polarization are connectable to the baseband unit 250 via a respective transmit and / or receive chain 260a. That is, antenna panel 240a is connectable to the baseband unit 250 via two transmit and / or receive chains in total. Further, antenna panel 240b is an antenna array with four columns and one row of dual-polarized antenna elements, where the antenna elements of each polarization are connectable to the baseband unit 250 via a respective transmit and / or receive chain 260b. That is, antenna panel 240b is connectable to the baseband unit 250 via two transmit and / or receive chains in total. Finally, antenna panel 240c is an antenna array with one column and four rows of single-polarized antenna elements, where all antenna elements are connectable to the baseband unit 250 via one and the same transmit and / or receive chain 260c. This is only one example implementation of a UE 200, and the example implementation is provided to illustrate the herein disclosed embodiments. For example, for the herein disclosed embodiments it is sufficient that the UE 200 comprises at least two antenna panels 240a:240c (and thus not necessarily three antenna panels 240a:240c). It is thus noted that the herein disclosed embodiments apply also to other implementation of the UE 200 as long as the UE 200 is capable of implementing the herein disclosed embodiments.

[0035] At least some of the herein disclosed embodiments relate to technologies for the UE 200 to, based on measurements on downlink reference signals, select one or more antenna panel 240a:240c for subsequence communication with at least one network node 110a, 110b. In some embodiments, the subsequence communication involves a beam management procedure. The one or more antenna panel 240a:240c are selected based on a performance metric to yield better performance than if the selection was only based on the received power of the downlink reference signals. Examples of such performance metrics will be disclosed below.

[0036] Fig. 3 is a flowchart illustrating embodiments of methods for selecting antenna panel 240a:240c in a UE 200. The UE 200 comprises at least two antenna panels 240a:240c. The methods are performed by the UE 200. The methods are advantageously provided as computer programs 820.

[0037] In general terms, which antenna panel 240a:240c for the UE 200 to use for communicating with the network node 110a, 110b is based on measurements on downlink reference signals as received by the UE 200 from the network node 110a, 110b, as in step S104.

[0038] S104: The UE 200 obtains measurements on downlink reference signals as received by the UE 200 from the network node 110a, 110b.

[0039] Further, the selection is based on a performance metric, with one value of the performance metric being calculated per each of the antenna panels 240a:240c, as in step S106.

[0040] S106: The UE 200 evaluates a performance metric for communicating with the network node 110a, 110b. The performance metric is based on the measurements. One performance metric value of the performance metric is calculated per each of the antenna panels 240a:240c. The performance metric at least pertains to at least one of throughput and latency.

[0041] The antenna panel 240a:240c with best performance metric value is then selected, as in step S108.

[0042] S108: The UE 200 selects, for communicating with the network node 110a, 110b, the antenna panel 240a:240c having best performance metric value.

[0043] Embodiments relating to further details of selecting antenna panel 240a:240c in the user equipment 200 as performed by the user equipment 200 will now be disclosed with continued reference to Fig. 3.

[0044] Once the antenna panel 240a:240c having best performance metric value has been selected, the UE 200 could communicate with the network node 110a, 110b using the selected antenna panel 240a:240c.

[0045] Hence, in some embodiments, the UE 200 is configured to perform (optional) step S110. S110: The UE 200 communicates with the network node 110a, 110b whilst using the selected antenna panel 240a: 240c.

[0046] In general terms, one purpose of the uplink reference signals is for sounding the channel from the UE 200 to each of the network nodes 110a, 110b. In some examples the uplink reference signal is a sounding reference signal (SRS), also referred to as an SRS resource. In some examples, the SRS resource is part of an SRS resource set.

[0047] In some aspects, the network node 110a, 110b configures the UE with uplink reference signals, such as with an SRS resource set. Hence, in some embodiments, the UE 200 is configured to perform (optional) step S102.

[0048] S102: The UE 200 receives configuration of an uplink reference signal resource set from the network node 110a, 110b.

[0049] Then, communicating with the network node 110a, 110b (as in step S110) comprises the UE 200 transmitting uplink reference signals from the uplink reference signal resource set from the selected antenna panel 240a:240c.

[0050] In some aspects, the configuration is for a certain usage, such as antenna switching, codebook based uplink transmission, non-codebook based uplink transmission, or beam management. In particular, in some embodiments, the antenna panel 240a:240c is selected as part of performing an uplink beam management procedure with the network node 110a, 110b.

[0051] In some examples, the uplink reference signals are configured with a downlink reference signal as a QCL source or are configured to follow an indicated unified a transmission configuration indicator (TCI) state to the UE, to facilitate the antenna panel selection for transmitting the configured uplink reference signals.

[0052] The downlink reference signals could be transmitted periodically from the network node 110a, 110b. In some examples, the downlink reference signals are synchronization signal block (SSB) signals or channel state information reference signals (CSI-RS).

[0053] There could be different types of measurements that are performed on the downlink reference signals. In some examples, the measurements are of received power, such as of reference signal received power (RSRP). In case the configured uplink reference signals are indicated with a QCL source associated with one of the uplink reference signals, then the UE mainly can focus on measurements of that downlink reference signal when selecting the antenna panel for the configured uplink reference signals.

[0054] In some aspects, the network node 110a, 110b triggers the UE to transmit the configured uplink reference signals, such that the network node 110a, 110b can determine a suitable beam pair link between the network node 110a, 110b and UE 200. Therefore, in some embodiments, performing the uplink beam management procedure further comprises the UE 200 transmitting the uplink reference signals in a set of beams from the selected antenna panel 240a:240c.

[0055] In some aspects, the triggering is only performed when the usage of the configured uplink reference signals is for beam management and / or when the UE 200 is configured for aperiodic transmission of the uplink reference signals. Further, such triggering can be useful in case the receiver in the network node 110a, 110b is equipped with a digital processing capability, since then, for beam management usage, the network node 110a, 110b can evaluate all candidate beams at the network node 110a, 110b for each transmitted uplink reference signal (i.e., for each beam at the UE 200 in case each uplink reference signal is transmitted in a respective beam from the UE 200). This means that based on a single transmission of the configured uplink reference signals the network node 110a, 110b can evaluate all candidate beam pair links between the network node 110a, 110b and the antenna panel 240a:240c that the UE 200 has selected for the transmission of the uplink reference signals, assuming that the UE 200 transmits one uplink reference signal per narrow beam from the selected antenna panel 240a:240c.

[0056] As disclosed above, the antenna panel selection is based on a performance metric as based on the measurements and evaluated for communicating with the network node 110a, 110b. As further disclosed above, instead of only using RSRP (or potentially signal to interference plus noise ratio, SINR) measured on one or more downlink reference signals, the UE also takes one or more other parameters into account, at least pertaining to at least one of throughput and latency. In particular, in some embodiments, the antenna panel 240a:240c having the best performance metric value (and thus the antenna panel 240a:240c that is selected in step S108) is the antenna panel 240a:240c that, according to the performance metric, out of all the at least two antenna panels 240a:240c yields highest throughput and / or lowest latency for communicating with the network node 110a, 110b.

[0057] In some aspects, the performance metric is based on the number of transmit and / or receive chains 260a:260c for each antenna panel 240a:240c. For example, the UE 200 might further comprise a baseband unit 250 (as in the example of Fig. 2) where each of the at least two antenna panels 240a:240c is connectable to the baseband unit 250 via at least one transmit and / or receive chain 260a:260c. Then, in some embodiments, the performance metric for a given antenna panel 240a:240c increases with via how many transmit and / or receive chains 260a:260c this given antenna panel 240a:240c is connectable to the baseband unit 250. Hence, the performance metric would be higher for antenna panel 240a than for antenna panel 240c in Fig. 2 since antenna panel 240a is connectable to the baseband unit 250 via two transmit and / or receive chains 260a whereas antenna panel 240c is connectable to the baseband unit 250 via only one single transmit and / or receive chain 260c.

[0058] In some aspects, the estimated downlink and / or uplink throughput takes into consideration an estimated downlink and / or uplink link budget and / or an estimated downlink and / or uplink rank into account. In particular, in some embodiments, the performance metric for a given antenna panel 240a:240c is dependent on the uplink and / or downlink rank achievable for communication with the network node 110a, 110b using this given antenna panel 240a:240c, where the performance metric increases with increased uplink and / or downlink rank. Hence, an antenna panel 240a:240c with a higher uplink and / or downlink rank is preferred over an antenna panel 240a:240c with a lower uplink and / or downlink rank. For example, with reference to the illustrative example in Fig. 2, assume that antenna panel 240a (which is connectable to the baseband unit 250 via two transmit and / or receive chains 260a) has highest RSRP but is in line of sight with the network node 110a, 110b and only supports an uplink and / or downlink rank of only 1 layer per polarization, whereas antenna panel 240c (which is connectable to the baseband unit 250 via only one single transmit and / or receive chain 260c) is not in line of sight with the network node 110a, 110b and supports an uplink and / or downlink rank of 2 layers per polarization. According to the present embodiment, the performance metric would prioritize selection of antenna panel 240c over antenna panel 240a.

[0059] In some aspects, in case the RSRP / SINR is slightly higher for a first antenna panel than for a second antenna panel, but the second antenna panel is associated with two transmit and / or receive chains, whilst the first antenna panel only is associated with a single transmit and / or receive chain, the UE, in accordance with the performance metric, selects the second antenna panel.

[0060] In some aspects, a relative threshold is used when the performance metric values are calculated such that if the RSRP for a first antenna panel associated with a single transmit and / or receive chain is more than x dB (where x is a relative threshold value) larger than the RSRP for a second antenna panel associated with two transmit and / or receive chains, the UE selects the first antenna panel. Otherwise, the UE selects the second UE panel (e.g., if the difference in RSRP between the two antenna panels are less than x dB). Hence, in some embodiments, the measurements are RSRP values, and, according to the performance metric, a first antenna panel 240a is selected over a second antenna panel 240c when the first antenna panel 240a is connectable to the baseband unit 250 via a higher number of transmit and / or receive chains 260a:260c than the second antenna panel 240c, unless the RSRP value for the second antenna panel 240c is more than a non-zero relative threshold value higher than the RSRP value for the first antenna panel 240a. Such a relative threshold can be used in the performance metric to prioritize selection of an antenna panel associated with N2 transmit and / or receive chains over an antenna panel associated with N1 transmit and / or receive chains, where N2 > N1.

[0061] In some aspects, an absolute threshold is used when the performance metric values are calculated such that if a given antenna panel has an RSRP less than a certain absolute threshold (e.g., RSRP smaller than y dBm, where, for example -140 < y < -120), then this given antenna panel is excluded from being selected. Hence, in some embodiments, the measurements are RSRP values, and, according to the performance metric, a given antenna panel 240a:240c is excluded from being selected when the RSRP value for this given antenna panel 240a:240c is below a non-zero absolute threshold value. Examples of further performance metrics will be disclosed next. In some non-limiting examples, the performance metric further pertains to at least one of: buffer status per antenna panel 240a:240c, available transmission power per antenna panel 240a:240c, overheating per antenna panel 240a:240c, P-MPR per antenna panel 240a:240c, beamforming gain per antenna panel 240a:240c, amount of antenna elements per antenna panel 240a:240c. For example, the available transmit power per antenna panel 240a: 240c can be useful if power amplifiers with different maximum power levels are used for different antenna panels. For example, potential differences in P-MPR between different antenna panels 240a:240c could be relevant, e.g., when one antenna panel is facing a human body and the transmit power needs to be reduced for that antenna panel. For example, potential panel overheating could be relevant such that selection of an antenna panel with a low risk of overheating is prioritized over selection of an antenna panel with a higher risk of overheating.

[0062] In some aspects, separate throughputs are estimated for downlink and uplink. That is, in some embodiments, separate performance metric values are calculated for the antenna panels 240a:240c for uplink and downlink communication with the network node 110a, 110b. For example, the link budget might be different in downlink and uplink due to different output powers in the downlink compared to the uplink.

[0063] In some aspects, in case a given antenna panel has best performance metric value for the downlink and another antenna panel has best performance metric value for the uplink, the antenna panel might further be selected depending on the buffer status, e.g., depending on if the UE is expected to receive most data in the downlink or transmit most data in the uplink for some future time interval when the selected antenna panel is to be used. Besides the amount of data, the service priority of the data can also be considered by the performance metric. In this way, a data transmission representing an uplink live video streaming could be prioritized over a data transmission representing a file download in the downlink.

[0064] In some aspects, the selection of antenna panel is based on previous evaluations. In particular, in some embodiments, the performance metric values at least partly are calculated based on historically obtained measurements on downlink reference signals as received from the network node 110a, 110b or from another network node 110a, 110b. For example, the UE might have been configured with a lookup table, where a certain RSRP / SINR values for an antenna panel associated with a certain number of transmit and / or receive chains is converted to an estimated throughput.

[0065] In some aspects, in case the UE support simultaneous multi-panel transmission and is configured for simultaneous communication with two (or more) different network nodes 110a, 110b (for example with two indicated unified TCI states), the UE might be configured with two sets of uplink reference signals. In such aspects, the UE should select one antenna panel per network node 110a, 110b. The selection is then, in accordance with the above, made by evaluating a performance metric based on measurements on downlink reference signals as received by the UE from the two network nodes 110a, 110b. Hence, in some embodiments, the UE 200 is configured for simultaneous communication with at least two network nodes 110a, 110b, and a respective one of the antenna panels 240a:240c is selected for communicating with a respective one of the at least two network nodes 110a, 110b.

[0066] The selection of antenna panel per network node 110a, 110b could either be independent per network node 110a, 110b or be performed jointly for both network nodes 110a, 110b. In the latter, the performance metric might thus take into account the total performance over both network nodes 110a, 110b. The performance metric might for this purpose consider cross inter-network node interference. Such cross inter-network node interference might, for example, otherwise cause significant interference between a first beam pair link selected for communication between the UE and a first network node 110a and a second beam pair link selected for communication between the UE and a second network node 110b. Therefore, in some embodiments, the UE 200 jointly selects which of the antenna panels 240a:240c to use for communicating with which of the at least two network nodes 110a, 110b based on the performance metric as evaluated for simultaneous communication with these at least two network nodes 110a, 110b. One particular embodiment for antenna panel selection in the UE 200 based on at least some of the above-disclosed embodiments in the context of an uplink beam management procedure will be disclosed next with reference to the signaling diagram in Fig. 4. In this embodiment, the uplink reference signals are represented by SRS resources.

[0067] Step S201 : The network node 110a configures the UE 200 with an SRS resource set (SRSsetl ) with usage for beam management.

[0068] Step S202: The network node 110a periodically transmits downlink reference signal resources in different beams.

[0069] Step S203: The UE 200 performs measurements on the downlink reference signal resources. The UE 200 identifies the downlink reference signal resource that out of all the received downlink reference signal resources yield best performance.

[0070] Step S204: The network node 110a triggers the UE 200 to transmit the SRS resources in SRSsetl .

[0071] Step S205: The UE 200 determines which one or more antenna panel 240a:240c from which the SRS resources in SRSsetl are to be transmitted. The selection is performed in accordance with any of the above disclosed embodiments, aspects, or examples, for antenna panel selection.

[0072] Step S206: The UE 200 indicates to the network node 110a the downlink reference signal resources yielding best performance and transmits the SRS resources in SRSsetl from the selected one or more antenna panel 240a:240c. In particular, the UE 200 might report the RSRP for the downlink reference signal resources yielding best performance.

[0073] Step S207: The network node 110a receives, and performs measures on, the SRS resources in SRSsetl . The network node 110a identifies the SRS resource that out of all the SRS resources in SRSsetl yield best performance. The network node 110a indicates the identified SRS resource to the UE 200.

[0074] Step S208: A beam pair is identified as the beam at the network node 110a corresponding to the downlink reference signal resources yielding best performance at the UE 200 and the SRS resource yielding best performance at the network node 110. The network node 110a and the UE 200 then communicate with each other using the defined beam pair. Simulation results will be shown next with reference to Fig. 5. In Fig. 5 is shown channel capacity (in terms of bits per second and Hertz; bps / Hz) as a function of uplink signal to noise ratio (SNR) of a frequency-selective Rayleigh fading MIMO. results are shown for an evaluation example for a case where different antenna panels at the UE have different number of TX chains. In more detail, results are shown for a UE having two antenna panels; a first antenna panel with one Tx chain and a second antenna panel with two TX chains, and where the total TX power is the same for both antenna panels. For the antenna panel with one TX chain, it is for illustrative purposes assumed that the path gain is 3 dB higher than for the antenna panel with two TX chains. This corresponds to 3 dB higher RSRP for the first antenna panel. Hence, according to state-of-the-art antenna panel selection, the first antenna panel would be selected. However, based on the herein disclosed embodiments, the second antenna panel would be selected based on yielding higher (uplink) throughput. It can be seen in Fig. 5 that for low SNR values, the first antenna panel gives slightly higher capacity, but for medium and high SNR values, the second antenna panel gives significantly higher capacity. Hence, since the second antenna panel has two TX chains, higher uplink throughput can be expected with this antenna panel for a wide range of SNR values, despite of yielding lower RSRP. This demonstrates that using state-of-the-art antenna panel selection based on RSRP can be expected to give lower performance compared to the herein disclosed embodiments.

[0075] Fig. 6 schematically illustrates, in terms of a number of structural units, the components of a user equipment 200 according to an embodiment. Processing circuitry 210 is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., capable of executing software instructions stored in a computer program product 810 (as in Fig. 8), e.g. in the form of a storage medium 230. The processing circuitry 210 may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA). Particularly, the processing circuitry 210 is configured to cause the user equipment 200 to perform a set of operations, or steps, as disclosed above. For example, the storage medium 230 may store the set of operations, and the processing circuitry 210 may be configured to retrieve the set of operations from the storage medium 230 to cause the user equipment 200 to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus, the processing circuitry 210 is thereby arranged to execute methods as herein disclosed. The storage medium 230 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory. The user equipment 200 may further comprise a communications (comm.) interface 220 at least configured for communications with other entities, functions, nodes, and devices, and at least with the network nodes 110a, 110b in Fig. 1 . As such the communications interface 220 may comprise one or more transmitters and receivers, comprising analogue and digital components. In this respect, the communications interface 220 might comprise the antenna panels 240a:240c. The processing circuitry 210 controls the general operation of the user equipment 200 e.g. by sending data and control signals to the communications interface 220 and the storage medium 230, by receiving data and reports from the communications interface 220, and by retrieving data and instructions from the storage medium 230. Other components, as well as the related functionality, of the user equipment 200 are omitted in order not to obscure the concepts presented herein.

[0076] Fig. 7 schematically illustrates, in terms of a number of functional modules, the components of a user equipment 200 according to an embodiment. The user equipment 200 of Fig. 7 comprises a number of functional modules; an obtain module 210b configured to perform step S104, an evaluate module 210c configured to perform step S106, and a select module 21 Od configured to perform step S108. The user equipment 200 of Fig. 7 may further comprise a number of optional functional modules, such as any of a receive module 210a configured to perform step S102, and a communicate (Comm.) module 21 Oe configured to perform step S110. In general terms, each functional module 210a:21 Oe may in one embodiment be implemented only in hardware and in another embodiment with the help of software, i.e., the latter embodiment having computer program instructions stored on the storage medium 230 which when run on the processing circuitry makes the user equipment 200 perform the corresponding steps mentioned above in conjunction with Fig 7. It should also be mentioned that even though the modules correspond to parts of a computer program, they do not need to be separate modules therein, but the way in which they are implemented in software is dependent on the programming language used. Preferably, one or more or all functional modules 210a:21 Oe may be implemented by the processing circuitry 210, possibly in cooperation with the communications interface 220 and / or the storage medium 230. The processing circuitry 210 may thus be configured to from the storage medium 230 fetch instructions as provided by a functional module 210a:21 Oe and to execute these instructions, thereby performing any steps as disclosed herein.

[0077] Fig. 8 shows one example of a computer program product 810 comprising computer readable storage medium 830. On this computer readable storage medium 830, a computer program 820 can be stored, which computer program 820 can cause the processing circuitry 210 and thereto operatively coupled entities and devices, such as the communications interface 220 and the storage medium 230, to execute methods according to embodiments described herein. The computer program 820 and / or computer program product 810 may thus provide means for performing any steps as herein disclosed. In the example of Fig. 8, the computer program product 810 is illustrated as an optical disc, such as a CD (compact disc) or a DVD (digital versatile disc) or a Blu-Ray disc. The computer program product 810 could also be embodied as a memory, such as a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), or an electrically erasable programmable read-only memory (EEPROM) and more particularly as a non-volatile storage medium of a device in an external memory such as a USB (Universal Serial Bus) memory or a Flash memory, such as a compact Flash memory. Thus, while the computer program 820 is here schematically shown as a track on the depicted optical disk, the computer program 820 can be stored in any way which is suitable for the computer program product 810. The inventive concept has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended patent claims.

Claims

CLAIMS1 . A method for selecting antenna panel (240a:240c) in a user equipment (200), the method being performed by the user equipment (200), the user equipment (200) comprising at least two antenna panels (240a:240c), the method comprising: obtaining (S104) measurements on downlink reference signals as received by the user equipment (200) from a network node (110a, 110b); evaluating (S106) a performance metric for communicating with the network node (110a, 110b), wherein the performance metric is based on the measurements, wherein one performance metric value of the performance metric is calculated per each of the antenna panels (240a:240c), and wherein the performance metric at least pertains to at least one of throughput and latency; and selecting (S108), for communicating with the network node (110a, 110b), the antenna panel (240a:240c) having best performance metric value.

2. The method according to claim 1, wherein the method further comprises: communicating (S110) with the network node (110a, 110b) whilst using the selected antenna panel (240a:240c).

3. The method according to claim 2, wherein the method further comprises: receiving (S102) configuration of an uplink reference signal resource set from the network node (110a, 110b); and wherein communicating with the network node (110a, 110b) comprises transmitting uplink reference signals from the uplink reference signal resource set from the selected antenna panel (240a: 240c).

4. The method according to any preceding claim, wherein the antenna panel (240a:240c) is selected as part of performing an uplink beam management procedure with the network node (110a, 110b).

5. The method according to a combination of claim 3 and claim 4, wherein performing the uplink beam management procedure further comprises the user equipment (200) transmitting the uplink reference signals in a set of beams from the selected antenna panel (240a:240c).

6. The method according to any preceding claim, wherein the antenna panel (240a:240c) having best performance metric value is the antenna panel (240a:240c) that, according to the performance metric, out of all the at least two antenna panels (240a:240c) yields highest throughput and / or lowest latency for communicating with the network node (110a, 110b).

7. The method according to any preceding claim, wherein the performance metric for a given antenna panel (240a:240c) of the antenna panels (240a:240c) is dependent on an uplink and / or downlink rank achievable for communication with the network node (110a, 110b) using said given antenna panel (240a:240c), and wherein the performance metric increases with increased uplink and / or downlink rank.

8. The method according to any preceding claim, wherein the user equipment (200) further comprises a baseband unit (250), and wherein each of the at least two antenna panels (240a:240c) is connectable to the baseband unit (250) via at least one transmit and / or receive chain (260a: 260c), and wherein the performance metric for a given antenna panel (240a:240c) of the antenna panels (240a:240c) increases with via how many transmit and / or receive chains (260a:260c) said given antenna panel (240a:240c) is connectable to the baseband unit (250).

9. The method according to claim 8, wherein the measurements are reference signal received power, RSRP, values, and wherein, according to the performance metric, a first antenna panel (240a) of the at least two antenna panels (240a:240c) is selected over a second antenna panel (240c) of the at least two antenna panels (240a:240c) when the first antenna panel (240a) is connectable to the baseband unit (250) via a higher number of transmit and / or receive chains (260a:260c) than the second antenna panel (240c), unless the RSRP value for the second antenna panel (240c) is more than a nonzero relative threshold value higher than the RSRP value for the first antenna panel (240a).

10. The method according to any preceding claim, wherein the measurements are reference signal received power, RSRP, values, and wherein, according to the performance metric, a given antenna panel (240a:240c) of the antenna panels (240a:240c) is excluded from being selected when the RSRP value for said given antenna panel (240a:240c) is below a non-zero absolute threshold value.11 . The method according to any preceding claim, wherein the performance metric further pertains to at least one of: buffer status per antenna panel (240a:240c), available transmission power per antenna panel (240a:240c), overheating per antenna panel (240a:240c), Power Management Maximum Power Reduction per antenna panel (240a:240c), beamforming gain per antenna panel (240a:240c), amount of antenna elements per antenna panel (240a:240c).

12. The method according to any preceding claim, wherein the performance metric values at least partly are calculated based on historically obtained measurements on downlink reference signals as received from the network node (110a, 110b) or from another network node (110a, 110b).

13. The method according to any preceding claim, wherein separate performance metric values are calculated for the antenna panels (240a:240c) for uplink and downlink communication with the network node (110a, 110b).

14. The method according to any preceding claim, wherein the user equipment (200) is configured for simultaneous communication with at least two network nodes (110a, 110b), and wherein a respective one of the antenna panels (240a:240c) is selected for communicating with a respective one of the at least two network nodes (110a, 110b).

15. The method according to claim 14, wherein the user equipment (200) jointly selects which of the antenna panels (240a: 240c) to use for communicating with which of the at least two network nodes (110a, 110b) based on the performance metric as evaluated for simultaneous communication with said at least two network nodes (110a, 110b).

16. A user equipment (200) for antenna panel selection, the user equipment (200) comprising at least two antenna panels (240a:240c), the user equipment (200) further comprising processing circuitry (210), the processing circuitry being configured to cause the user equipment (200) to: obtain measurements on downlink reference signals as received by the user equipment (200) from a network node (110a, 110b); evaluate a performance metric for communicating with the network node (110a, 110b), wherein the performance metric is based on the measurements, wherein one performance metric value of the performance metric is calculated per each of the antenna panels (240a:240c), and wherein the performance metric at least pertains to at least one of throughput and latency; and select, for communicating with the network node (110a, 110b), the antenna panel (240a:240c) having best performance metric value.

17. A user equipment (200) for antenna panel selection, the user equipment (200) comprising at least two antenna panels (240a: 240c), the user equipment (200) further comprising:an obtain module (210b) configured to obtain measurements on downlink reference signals as received by the user equipment (200) from a network node (110a, 110b); an evaluate module (210c) configured to evaluate a performance metric for communicating with the network node (110a, 110b), wherein the performance metric is based on the measurements, wherein one performance metric value of the performance metric is calculated per each of the antenna panels (240a:240c), and wherein the performance metric at least pertains to at least one of throughput and latency; and a select module (21 Od) configured to select, for communicating with the network node (110a, 110b), the antenna panel (240a:240c) having best performance metric value.

18. The user equipment (200) according to claim 16 or 17, further being configured to perform the method according to any of claims 2 to 15.

19. A computer program (820) for antenna panel selection, the computer program comprising computer code which, when run on processing circuitry (210) of a user equipment (200) comprising at least two antenna panels (240a:240c), causes the user equipment (200) to: obtain (S104) measurements on downlink reference signals as received by the user equipment (200) from a network node (110a, 110b); evaluate (S106) a performance metric for communicating with the network node (110a, 110b), wherein the performance metric is based on the measurements, wherein one performance metric value of the performance metric is calculated per each of the antenna panels (240a: 240c), and wherein the performance metric at least pertains to at least one of throughput and latency; and select (S108), for communicating with the network node (110a, 110b), the antenna panel (240a:240c) having best performance metric value.

20. A computer program product (810) comprising a computer program (820) according to claim 19, and a computer readable storage medium (830) on which the computer program is stored.

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