Multi-resource uplink sounding and antenna subset transmission

Abstract

The present application relates to multi-resource uplink sounding and antenna subset transmission, including a method (900) for transmitting on different antenna subsets of a user equipment (UE) (50), the method (900) comprising: sending (902) an indication that the UE (50) is capable of transmitting a plurality of different sounding reference signal (SRS) resources, wherein each SRS resource comprises at least one SRS port; sending capability information, the capability information indicating that the UE (50) is capable of transmitting simultaneously on a plurality of SRS resources; receiving an SRS configuration of a plurality of SRS resource lists, wherein each SRS resource list comprises a group of SRS resources that the UE cannot transmit simultaneously; simultaneously transmitting SRS resources selected from different lists of the plurality of SRS resource lists; receiving (906) an indication of at least one SRS resource; and sending (908) a physical channel on an antenna of the UE associated with the indicated at least one SRS resource.

Description

[0001] This application is a divisional application of patent application No. 201880038763.1 in the name of PCT International Application PCT / SE2018 / 050632 entered into the Chinese national phase on June 15, 2018, with the title "Multiple Resource Uplink Sounding and Antenna Subset Transmission". TECHNICAL FIELD

[0002] The present disclosure relates generally to wireless networks, and more specifically to the use and configuration signaling of uplink sounding reference signals for wireless devices with multiple antennas, including transmission and reception on different antenna subsets in the wireless device. BACKGROUND

[0003] The next generation mobile wireless communication system currently being developed by the Third Generation Partnership Project (3GPP), often referred to as 5G or "New Radio" (NR), will support a variety of use cases and a variety of deployment scenarios. The latter includes deployments in both low frequencies (hundreds of MHz), similar to today's Long Term Evolution (LTE) systems, and very high frequencies (mmWave at tens of GHz).

[0004] As in the case of LTE, NR will use Orthogonal Frequency Division Multiplexing (OFDM) in the downlink (i.e., from network node gNB, eNB or other base station to user equipment or UE). In the uplink (i.e., from UE to gNB), both Discrete Fourier Transform (DFT)-spread OFDM and OFDM will be supported.

[0005] The basic NR physical resource can thus be seen as a time-frequency grid similar to in LTE, as FIG. 1 shown in Fig. 1, where each resource element corresponds to one OFDM subcarrier during one OFDM symbol interval. Although FIG. 1 one subcarrier interval of Δf = 15 kHz is shown in Fig. 1, different subcarrier spacing values are supported in NR. The supported subcarrier spacing values (also referred to as different numerologies) in NR are given by Δf = (15 x 2 α ) kHz, where is a non-negative integer.

[0006] Furthermore, resource allocation in LTE is often described in terms of resource blocks (RBs), where a resource block corresponds to one slot (0.5 ms) in the time domain and 12 consecutive subcarriers in the frequency domain. In the frequency domain, the resource blocks are numbered starting with 0 from one end of the system bandwidth. For NR, a resource block is also 12 subcarriers in the frequency domain, but further studies are needed in the time domain. In the following discussion, RB is also referred to as (interchangeably) physical RB (PRB).

[0007] In time domain, downlink and uplink transmissions in NR will be organized into equally sized subframes as in LTE, as shown in FIG. 2 Figure 1. In NR, the reference numerology (15 x 2 α kHz subframe length is exactly 1 / 2 α ms.

[0008] Downlink transmissions are dynamically scheduled, i.e., in each subframe, the gNB transmits downlink control information (DCI) about which UE data will be transmitted to this gNB and on which resource blocks in the current downlink subframe the data will be transmitted. According to current understanding, this control signaling will typically be transmitted in the first one or two OFDM symbols in each subframe in NR. This control information is carried on the physical control channel (PDCCH) and data is carried on the physical downlink shared channel (PDSCH). A UE first detects and decodes the PDCCH and, if the PDCCH is successfully decoded, the UE decodes the corresponding PDSCH based on the control information decoded in the PDCCH. Each UE is assigned a C-RNTI (Cell Radio Network Temporary Identifier) that is unique within the same serving cell. The CRC (Cyclic Redundancy Check) bits of the PDCCH for a UE are scrambled with the C-RNTI of this UE, so the UE identifies its PDCCH by checking the C-RNTI used to scramble the CRC bits of the PDCCH.

[0009] Uplink data transmissions are also dynamically scheduled using the PDCCH. A UE first decodes an uplink grant in the PDCCH and then transmits data on the physical uplink shared channel (PUSCH) based on the decoded control information in the uplink grant, which can specify the modulation order, coding rate, uplink resource allocation, etc.

[0010] In LTE, both uplink and downlink also support semi-persistent scheduling (SPS), whereby a series of periodic data transmissions are activated or deactivated by a single PDCCH. By using SPS, no PDCCH is transmitted for data transmissions after activation. In SPS, the CRC of the PDCCH is scrambled by an SPS-C-RNTI, which is configured to the UE if the UE supports SPS.

[0011] In addition to the PUSCH, a physical uplink control channel (PUCCH) is supported in NR to carry uplink control information (UCI), e.g., acknowledgement (ACK), negative acknowledgement (NACK) or channel state information (CSI) feedback related to HARQ (Hybrid Automatic Repeat Request).

[0012] Codebook-based precoding

[0013] Multi-antenna technology can significantly increase the data rates and reliability of a wireless communication system. The performance is particularly improved if both the transmitter and the receiver are equipped with multiple antennas, which will form a Multiple-Input Multiple-Output (MIMO) communication channel. Such systems and / or related technology are often referred to as MIMO.

[0014] Although the NR standard is currently being specified, the core components in NR are expected to support MIMO antenna deployments and MIMO related technology. It is expected that NR will support uplink MIMO and use at least 4 antenna ports with channel dependent precoding for at least 4 layers of spatial multiplexing. The spatial multiplexing mode is intended to achieve high data rates under favorable channel conditions. For the case of using CP-OFDM (Cyclic Prefix OFDM) on the uplink, FIG. 3 An illustration of the spatial multiplexing operation is provided in

[0015] It can be seen that the information carried by the symbol vector s is multiplied by N T x a precoder matrix W, which is used to allocate the transmit energy into a subspace of the N T ( corresponding to N T antenna ports) dimensional vector space. The precoder matrix is typically selected from a codebook of possible precoder matrices and is typically indicated by means of a Transmit Precoder Matrix Indicator (TPMI), which specifies a unique precoder matrix in the codebook among a given number of symbol streams. The r symbols in s correspond to one layer each, and r is referred to as the transmission rank. In this way, spatial multiplexing can be achieved since multiple symbols can be transmitted simultaneously on the same Time / Frequency Resource Element (TFRE). The number of symbols r is typically adapted to accommodate the current channel properties.

[0016] Since uplink MIMO in NR supports CP-OFDM, the NR MIMO codebook design does not need to consider the increase of UE Power Amplifier Peak to Average Power Ratio (PAPR) as a design factor as required for LTE Release 10 uplink MIMO. Therefore, both codebooks with limited PAPR increase and codebooks with relatively high PAPR increase are suitable for NR uplink MIMO. Thus, suitable codebooks for NR uplink MIMO can include the uplink MIMO codebooks defined in Section 5.3.3A of the previously existing 3GPP Technical Specification 36.211, as well as the downlink MIMO codebooks in Section 6.3.4.2.3 of 3GPP Technical Specification 36.211 and Section 7.2.4 of 3GPP Technical Specification 36.213.

[0017] The N Rx 1 vector y n (or data TFRE number n) is modeled by the following equation:

[0018]

[0019] where e n is a noise / interference vector obtained as an implementation of a random process. The precoder W can be a wideband precoder, which is constant over the entire frequency range, or frequency selective.

[0020] The precoder matrix W is typically chosen to match the properties of N Rx N T the MIMO channel matrix H n , resulting in so-called channel dependent precoding. This is also often referred to as closed loop precoding, and essentially strives to concentrate the transmit energy on a subspace that is strong in the sense of conveying a large amount of transmit energy to the UE. In addition, the precoder matrix can also be chosen to strive to make the channel orthogonal, meaning that the inter-layer interference is reduced after proper linear equalization at the UE.

[0021] One example method for the UE to select the precoder matrix W can be to select W k that maximizes the Frobenius norm of the assumed equivalent channel:

[0022]

[0023] where

[0024] is a channel estimate possibly derived from a sounding reference symbol (SRS).

[0025] W k is the assumed precoder matrix, indexed by k.

[0026] is the assumed equivalent channel.

[0027] In closed-loop precoding for NR uplink, a transmission point (TRP) sends to a UE a TPMI that the UE should use on its uplink antennas based on channel measurements in the reverse link (uplink). (The term "TRP" can correspond to a particular eNB, gNB, access point, or other transmission point, or to a controller of one or more transmission points.) A gNodeB (gNB) configures the UE to send SRS according to the number of UE antennas that it wants the UE to use for uplink transmission to enable channel measurements. A single precoder that should cover a large bandwidth (wideband precoding) can be signaled. It can also be beneficial to match the frequency variation of the channel and instead feed back a precoding report that is frequency-selective (e.g., several precoders and / or several TPMIs) per subband.

[0028] Other information than TPMI is typically used to determine the uplink MIMO transmission state, e.g., SRS resource indicator (SRI) and transmission rank indicator (TRI). These parameters, as well as the modulation and coding state (MCS) and the uplink resources in which the PUSCH is to be sent, are also determined by the channel measurements resulting from the SRS transmission from the UE. The transmission rank as well as the number of spatial multiplexing layers is reflected in the number of columns of the precoder w. To improve performance, it is important to select a transmission rank that matches the channel properties.

[0029] CSI-RS resources

[0030] In LTE, if a Type B eMIMO is used, a UE can be configured with multiple channel state information reference symbol (CSI-RS) resources for downlink channel state information (CSI) acquisition purposes. A CSI-RS resource defines a certain number of CSI-RS at a certain location in the time-frequency resource grid and can be associated with a certain quasi co-location (QCL) assumption and a relative power level with respect to another reference signal. Typically, the CSI-RS in each CSI-RS resource is precoded with a different precoding weight to form different transmit beams. As part of the CSI reporting procedure, a UE can utilize a CSI-RS resource indicator (CRI) to select a preferred CSI-RS resource corresponding to a preferred transmit beam. The UE then determines an appropriate PMI, RI, and corresponding CQI for the selected CSI-RS resource by performing a precoder search. Thus, the UE first selects the best CSI-RS resource and then applies a precoder codebook within the selected CSI-RS resource.

[0031] Control signaling

[0032] LTE control signaling can be carried in various ways, including being carried on PDCCH or PUCCH, embedded in PUSCH, in a medium access control (MAC) control element (MAC CE), or in radio resource control (RRC) signaling. Each of these mechanisms is tailored to carry a specific kind of control information.

[0033] Control information carried on PDCCH, PUCCH, or embedded in PUSCH ("based on" PUSCH) is physical layer related control information, e.g., downlink control information (DCI), uplink control information (UCI), as described in 3GPP TS 36.21 1, 3GPP TS 36.212, and 3GPP TS 36.213. DCI is typically used to instruct a UE to perform a certain physical layer function and provide the information needed to perform the function. UCI is typically used to provide the network with the information it needs, e.g., HARQ-ACK, scheduling request (SR), channel state information (CSI) including CQI, PMI, RI, and / or CRI. UCI and DCI can be sent on a subframe-by-subframe basis, and are thus designed to support rapidly changing parameters, including those that can change with a rapidly fading radio channel. Because UCI and DCI can be sent in every subframe, the UCI or DCI corresponding to a given cell tends to be on the order of tens of bits, to limit the amount of control overhead.

[0034] Control information carried in MAC CEs is carried in MAC headers on uplink and downlink shared transport channels (UL-SCH and DL-SCH), as described in 3GPP TS 36.321. Because the size of a MAC header is not fixed, control information in MAC CEs can be sent when needed, and does not necessarily represent a fixed overhead. Moreover, because MAC CEs are carried in UL-SCH or DL-SCH transport channels, MAC CEs can effectively carry larger control payloads (this is facilitated by link-adaptive HARQ), and can be Turbo encoded. MAC CEs are used to perform repetitive tasks that use a fixed set of parameters, e.g., maintaining timing advance or buffer status reporting, but these tasks typically do not require MAC CEs to be transmitted on a subframe-by-subframe basis. Thus, none of the MAC CEs in LTE up to Release 14 carry channel state information related to rapidly fading radio channels (e.g., PMI, CQI, RI, and CRI).

[0035] Multi-panel UE antenna arrays

[0036] When constructing a UE antenna array, it can be challenging to obtain antennas with the same angular coverage such that they are typically seen by a given receiving TRP with the same power level. This is particularly challenging at the millimeter wave frequencies supported by NR. Furthermore, it can be difficult to place the antennas and transmitter (TX) chains of all UEs in close proximity in the limited space available in a small mobile device. One construction practice is to use a modular approach in which the UE TX chains are divided into "panels," each panel having one or more transmit chains, as shown in FIG. 4 As discussed in 3GPP Technical Report 38.802, such multi-panel UEs are typically modeled as having panels with element patterns pointing in different directions, while the antenna elements within a panel have element patterns pointing in approximately the same direction. Because the transmit chains in different panels can be separated in the UE, it can be more difficult to maintain calibration and phase coherence between the antenna elements in different panels as compared to maintaining calibration and phase coherence between the antenna elements in one panel. Thus, there can be frequency offsets, timing misalignments, and / or phase offsets between panels. The aspects of phase coherence between the TX chains of different panels are further discussed below.

[0037] FIG. 4 The example in FIG. 1 shows a 4-panel UE array with a total of 8 antenna elements. Each panel includes 2 elements, which have similar antenna patterns, driven by independent TX chains. The beamwidth of the antenna element patterns is approximately 90 degrees, such that the 4 panels cover all directions. Note that while the term "panel" conceptually relates to the concept of having physically distinct and separate groups of antennas (e.g., as implemented on separate printed circuit boards), its use in this document should not be understood as limited to groups of antennas that are physically separate and distinct in that sense.

[0038] SRS transmission in NR

[0039] The sounding reference signal (SRS) is used in LTE for various purposes and is expected to be used for similar purposes in NR. One main use of SRS is for uplink channel state estimation, allowing for channel quality estimation to enable uplink link adaptation (including determining which MCS state the UE should transmit at) and / or frequency selective scheduling. In the context of uplink MIMO, SRS can also be used to determine a precoder and number of layers that, when used by the UE to transmit on the uplink antenna array, will provide good uplink throughput and / or SINR. Other uses include power control and uplink timing advance adjustment.

[0040] Unlike UEs designed according to Release 14 of the LTE standard, at least some NR UEs can be capable of transmitting multiple SRS resources. Conceptually, this is similar to the use of multiple CSI-RS resources on the downlink: an SRS resource includes one or more SRS ports, and a UE can apply a beamformer and / or precoder to the SRS ports within an SRS resource so that they are transmitted with the same effective antenna pattern. The primary motivation for defining multiple SRS resources in a UE is to support analog beamforming in the UE, where the UE can transmit various beam patterns, but only one at a time. Such analog beamforming can have a relatively high directivity, especially at the higher frequencies that NR can support.

[0041] Early LTE uplink MIMO and transmit diversity designs did not focus on the case where high directivity beamforming can be used on different SRS ports, so a single SRS resource was sufficient. When an NR UE transmits on different beams, the power received at a TRP can be substantially different depending on which beam is used. One approach can be to have a single SRS resource, but indicate to the UE which beam to use for transmission. However, since UE antenna designs vary widely among UEs, and UE antenna patterns can be highly irregular, it is not feasible to have a predetermined set of UE antenna patterns that a TRP can exploit to control UE uplink precoding or beamforming. Therefore, an NR UE can transmit on multiple SRS resources, using a different effective antenna pattern on each SRS resource, thereby allowing a TRP to determine the composite channel characteristics and quality of the different effective antenna patterns used by the UE. Given this association of each effective antenna pattern with a corresponding SRS resource, the TRP can then indicate to the UE which of the one or more effective antenna patterns should be used for transmission on PUSCH (or other physical channels or signals) for one or more SRS resource indicators or "SRIs."

[0042] Depending on the implementation of the UE, it can be possible to maintain the relative phase among the transmit chains to each other. In this case, the UE can select the beam on each transmit chain by using different gains and / or phases among the transmit chains, and form an adaptive array by transmitting the same modulated symbol on the selected beams of the two transmit chains. This transmission of a common modulated symbol or signal on multiple antenna elements with controlled phase can be labeled as "coherent" transmission. Support for coherent uplink MIMO transmission in LTE Release 10 was indicated by a feature group indication for relative transmit phase continuity for uplink spatial multiplexing, where the UE indicates whether it can sufficiently maintain the relative phase of the transmit chains over a period of time to support coherent transmission.

[0043] In other UE implementations, the relative phases of the transmit chains can not be well controlled, and coherent transmission can not be used. In such implementations, it can still be possible to transmit on one of the transmit chains at a time, or to transmit different modulation symbols on the transmit chains. In the latter case, the modulation symbols on each transmit chain can form a spatial multiplexing layer or "MIMO" layer. Such transmission schemes can be referred to as "non-coherent" transmission. LTE Release 10 UEs with multiple transmit chains but without support for relative transmit phase continuity can use such non-coherent transmission schemes.

[0044] FIG. 5 An example of using analog beamforming on multiple transmit chains is shown. Here, each transmit chain includes a power amplifier that can be switched between a set of beams produced by a phase array. The transmit chains are divided into two sets, each with two transmit chains. The transmit chains in each set have the same beam direction, while different sets can have beams covering different directions. For illustration, assume that each transmit chain can select one of four analog beams, and that the two sets of transmit chains point in opposite directions. Thus, each set of transmit chains can correspond to a "panel" as defined in 3GPP TR 38.900 and 3GPP TR 38.802, and the term "panel" is used herein for illustration.

[0045] In FIG. 5 In this example, assume that effective antenna patterns #0 and #7 are selected for simultaneous transmission on the first and second panels, respectively. However, due to the use of analog beamforming, for example, effective antenna patterns #0 and #1 cannot be transmitted simultaneously because they are analog beams selected within one panel. Since UE implementations can vary, a mechanism is needed to allow the TRP to determine which effective antenna patterns the UE can transmit simultaneously based on the use of multiple SRS ports and resources. A second issue is how to determine whether coherent transmission can be made between SRS ports associated with different SRS resources. The relative transmit phase continuity of LTE UEs applies to all transmit chains, which can be overly simplistic for multi-panel NR UEs since phase coherence between intra-panel elements can be easier to achieve than across panels.

[0046] Power control

[0047] In mobile systems, setting the output power levels of the transmitters, base stations in the downlink, and mobile stations in the uplink is commonly referred to as power control (PC). The goals of PC include improving capacity, coverage, improving system robustness, and reducing power consumption.

[0048] In LTE, PC mechanisms can be classified into the following groups: (i) open loop, (ii) closed loop, and (iii) combined open and closed loop. These differ in the input used for determining the transmit power. In the open loop case, the transmitter measures certain signals transmitted by the receiver and sets its output power based on this. In the closed loop case, the receiver measures the signals from the transmitter and sends a transmit power control (TPC) command to the transmitter based on this, which then sets its transmit power accordingly. In the combined open and closed loop scheme, both inputs are used for setting the transmit power.

[0049] In a system with multiple channels (e.g., traffic and control channels) between the terminal and the base station, different power control principles can be applied to different channels. Using different principles gives more freedom in adapting the power control principle to the needs of the individual channels. The drawback is the increased complexity of maintaining several principles.

[0050] For example, in LTE Release 10, the setting of the UE transmit power for physical uplink control channel (PUCCH) transmissions is defined as follows.

[0051]

[0052] Here, P PUCCH is the transmit power to be used in a given subframe, and PL DL is the path loss estimated by the UE. For PUSCH, the following equation is used instead:

[0053]

[0054] where c denotes the serving cell, and P PUSCH,c is the transmit power to be used in a given subframe. Note also that PL DL is part of the setting of the power level of the UE transmission. It is clear from this that the path loss estimation by the UE plays an important role in the PC. The path loss in turn has to be estimated from downlink (DL) transmissions, and this is typically done by measuring reference signals. SUMMARY

[0055] Although NR will support multiple SRS transmissions to facilitate the use of analog beamforming in the UE, no mechanism has been defined for determining which UE beams can be transmitted simultaneously or which can be coherently combined.

[0056] According to several embodiments described in detail below, a UE indicates that it can transmit multiple different SRS resources, where each SRS resource includes multiple SRS ports. For example, the network can use this indication to determine how many beams the UE needs to have good angular coverage and to determine how many layers the UE can transmit in a similar direction. The indication can also be used to determine how many layers the UE can transmit from a UE panel.

[0057] In some embodiments, the UE also indicates SRS resource groups, where each SRS in a group can not be transmitted at the same time, but SRS resources in different groups can be transmitted at the same time. The network can use this information to determine on which transmit chains the UE can transmit at the same time.

[0058] In some embodiments, the UE subsequently receives an indication of at least one SRS resource that it should use to determine the precoding of a PUSCH. The UE should apply the same precoder or analog beamformer as used for each SRS port in the selected SRS resource to form a virtual array of elements carrying the PUSCH, where the virtual array has the same number of PUSCH virtual antennas as in the indicated SRS resource. In some embodiments, the UE can also receive a TPMI indicating the precoder that it should use to combine the virtual elements, allowing coherent combining of the PUSCH antenna elements corresponding to the SRS ports within the selected SRS resource.

[0059] Finally, in some embodiments, the UE transmits a PUSCH using the precoding and / or analog beamforming determined from the selected SRS and / or TPMI.

[0060] According to some aspects of the techniques disclosed herein, a UE that is adapted to transmit on different antenna subsets transmits an indication that the UE can transmit multiple different RS resources, where each RS resource includes at least one RS port. The UE transmits capability information indicating that the UE is capable of transmitting on multiple RS resources at the same time, and / or receives a first and second RS configuration, where the first RS configuration is a first list of SRS resources corresponding to at least the RS resource indication for a PUSCH transmission, and the second RS configuration is a second list of RS resources that can be used for SRS transmission. The UE receives an indication of at least one RS resource, and transmits a physical channel on the UE’s antennas associated with the indicated RS resource.

[0061] According to some embodiments, a method in a UE of transmitting on different subsets of antennas in the UE includes transmitting an indication that the UE can transmit a plurality of different RS resources, where each RS resource includes a plurality of RS ports. The method includes transmitting an indication of which RS resources the UE can transmit on simultaneously. The method also includes receiving an indication of at least one RS resource, and transmitting a physical channel on the antennas of the UE associated with the indicated at least one RS resource.

[0062] In some embodiments, the UE indicates that it is unable to control the relative phase between antenna ports when it transmits on the antenna ports corresponding to different SRS resources. The UE can then receive an indication of a plurality of SRS resources, then transmit one modulation symbol on an antenna corresponding to one of the SRS resources, and a different modulation symbol on a different antenna corresponding to a second SRS resource. In this way, non-coherent MIMO transmission with different MIMO layers on different subsets of antennas can be supported in a UE that does not support coherent combining of all of its transmit chains.

[0063] In some related embodiments, the UE receives a plurality of TPMI, where each TPMI corresponds to one of a plurality of SRS resources, and indicates a precoder that is to be applied to combine virtualized PUSCH antenna elements corresponding to each of the SRS ports in each SRS resource. In this way, coherent MIMO transmission can be used on transmit chains corresponding to SRS resources, while non-coherent MIMO transmission with different MIMO layers is used for different subsets of antennas corresponding to different SRS resources.

[0064] With the techniques and apparatus described herein, a UE with analog beamforming and multiple TX chains can transmit on all of the TX chains. A UE that supports coherent combining of different analog beams can transmit MIMO layers on different analog beams. A UE that does not support coherent combining of analog beams can transmit different MIMO layers on different analog beams.

[0065] According to some embodiments, a method in a network node of a wireless network of receiving transmissions from a UE on different subsets of antennas in the UE includes receiving an indication that the UE can transmit a plurality of different RS resources, where each RS resource includes a plurality of RS ports. The method also includes receiving an indication of which RS resources the UE can transmit on simultaneously, and selecting at least one RS resource based on the received indications. The method further includes transmitting an indication of the selected at least one RS resource to the UE, and receiving a physical channel transmitted by the UE on the antennas of the UE associated with the indicated at least one RS resource.

[0066] According to some embodiments, a method in a network node of a wireless network of receiving transmissions from a UE on different antenna subsets of the UE comprises receiving an indication that the UE can transmit a plurality of different RS resources, where each RS resource comprises at least one RS port. The method further comprises receiving capability information indicating that the UE is capable of transmitting on multiple RS resources simultaneously; and / or transmitting, to the UE, first and second RS configurations, where the first RS configuration is a first list of SRS resources corresponding to at least the RS resource indication for PUSCH transmission, and the second RS configuration is a second list of RS resources available for SRS transmission; and / or transmitting, to the UE, a transmission request, where the transmission request is constructed by the network node to avoid indicating to the UE to transmit SRS resources that the UE is not capable of transmitting simultaneously. The method further comprises selecting at least one RS resource based on the received indication; transmitting, to the UE, an indication of the selected at least one RS resource; and receiving a physical channel transmitted by the UE on the UE's antennas associated with the indicated at least one RS resource.

[0067] According to some embodiments, a UE adapted to transmit on different antenna subsets of the UE comprises transceiver circuitry; a memory, operatively coupled to the transceiver circuitry; and a memory coupled to the processing circuitry, the memory storing instructions executed by the processor such that the processor is configured to control the transceiver circuitry. The transceiver circuitry is controlled to transmit an indication that the UE can transmit a plurality of different RS resources, where each RS resource comprises a plurality of RS ports; and transmit an indication of which RS resources the UE can transmit simultaneously. The transceiver circuitry is further controlled to receive an indication of at least one RS resource, and transmit a physical channel on the UE's antennas associated with the indicated at least one RS resource.

[0068] According to some embodiments, a network node of a wireless network adapted to receive transmissions from a UE on different antenna subsets of the UE comprises transceiver circuitry; a processor, operatively coupled to the transceiver circuitry; and a memory coupled to the processing circuitry, the memory storing instructions executed by the processor such that the processor is configured to control the transceiver circuitry. The transceiver circuitry is controlled to receive an indication that the UE can transmit a plurality of different RS resources, where each RS resource comprises a plurality of RS ports. The transceiver circuitry is further controlled to receive an indication of which RS resources the UE can transmit simultaneously, and select at least one RS resource based on the received indication. The transceiver circuitry is controlled to transmit, to the UE, an indication of the selected at least one RS resource, and receive a physical channel transmitted by the UE on the UE's antennas associated with the indicated at least one RS resource.

[0069] Further embodiments can include apparatuses, computer program products, and non-transitory computer-readable media storing instructions that, when executed by processing circuitry, perform the operations of the above-described embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0070] FIG. 1 A basic NR physical resource is shown.

[0071] FIG. 2 An LTE time domain structure with 15 kHz subcarrier spacing is shown.

[0072] FIG. 3 A transmission structure for precoding spatial multiplexing in NR is shown.

[0073] FIG. 4 An example 4-panel, 8-element UE antenna array is shown.

[0074] FIG. 5 An example 2-panel UE antenna array, each panel having four different effective antenna patterns, is shown.

[0075] FIG. 6 is a process and signal flow diagram illustrating an example technique in accordance with some embodiments of the application.

[0076] FIG. 7 A UE that supports different numbers of SRS resources per panel is shown.

[0077] FIG. 8 An example UE is shown.

[0078] FIG. 9 is a process flow diagram illustrating an example method in accordance with some embodiments.

[0079] FIG. 10 An example network node is shown.

[0080] FIG. 11 is a process flow diagram illustrating another example method in accordance with some embodiments.

[0081] FIG. 12 and FIG. 13 Channel gains achievable between different transmission schemes and different codebooks when 1 -stage transmission through 2 single-port panels at 28 GHz is shown.

[0082] FIG. 14 and FIG. 15 Channel gains achievable between different transmission schemes and different codebooks when 1 -stage transmission through 4 single-port panels at 28 GHz is shown.

[0083] FIG. 16 is a functional representation of an example UE.

[0084] FIG. 17 is a functional representation of an example network node. DETAILED DESCRIPTION

[0085] PUSCH transmission based on multiple SRIs

[0086] As mentioned above, a UE can be instructed to transmit PUSCH using multiple SRIs, and this transmission can be done coherently or non-coherently. In order for the TRP or gNB to associate a given SRI with a UE effective antenna pattern, the eNB (or gNB, or other base station or access point) should know how many effective antenna patterns the UE requires, and also how many antenna ports the UE must transmit simultaneously using the same effective antenna pattern.

[0087] FIG. 6 A flowchart summarizing some embodiments of the techniques described herein for addressing these issues is shown. In this figure, as in the rest of this document, the term "UE" can be understood to refer to any wireless device that supports transmitting SRS on multiple SRS resources, while the term "TRP" can correspond to a specific eNB, gNB, access point, or other transmission point, or to the controller of one or more transmission points. Similarly, the term "gNB," which is typically used in NR to describe a base station, should be understood herein to refer more generally to any base station, access point, or transmission point.

[0088] exist FIG. 6 In the first step shown, the UE sends information about how many SRS resources the UE wants to use, how many SRS resources can be sent simultaneously, and the number of ports for each SRS resource (box 602). This may include indicating the number of SRS resource groups, the number of SRS resources per group, and the number of SRS ports per SRS resource. In some embodiments, this step includes an indication of which SRS resources the UE can send simultaneously. In some embodiments described in more detail below, a fixed mapping can be used to determine the SRS resources that can be sent simultaneously based on the number of SRS resource groups and the number of SRS resources per group. In other embodiments, more parameters are used to identify the SRS resources that can be sent simultaneously. Generally, as will be described in more detail below, this step can be accomplished in many different ways.

[0089] exist FIG. 6 In the next step shown, the TRP defines the SRS resources that should be used for the UE based on the information about the UE capabilities received in the first step and signals this information to the UE (block 604). This may include configuring the SRS resources and corresponding SRI for the UE based on the information in the UE capabilities.

[0090] Whenever the UE should be scheduled for UL transmission, the TRP starts sending SRS transmission requests to the UE, informing it which SRS resources it should send (block 606). Based on the earlier configuration of the SRS resources, the UE can map each SRS resource directly to a certain beam of a certain transmit chain. The TRP can use the indication about which SRS resources the UE can send simultaneously to avoid instructing the UE to send SRS resources that the UE cannot send simultaneously.

[0091] In the next step, the UE sends the SRS resources (block 608) and performs TRP measurements on them and determines the preferred SRS resource and the corresponding TPMI for the upcoming UL transmission (block 610). The TRP then signals the SRI and TPMI to the UE, and the UE applies them to the upcoming PUSCH transmission (block 612). Note that the arrows and text blocks with dashed lines are optional elements, as they do not necessarily have to be present in every implementation or instance of the illustrated method.

[0092] UE capabilities for SRS resources and PUSCH transmission

[0093] Mechanisms to indicate the UE capabilities for SRS resources and PUSCH transmission are described herein. By way of example configurations, these mechanisms can be understood where analog beamforming is used on 4 transmit chains, each “panel” has 2 transmit chains, and the panels cover different directions. Of course, the mechanisms herein can be generalized to cover any number of “panels”, or sets of transmit chains, each set having an arbitrary number of transmit chains. FIG. 5

[0094] In the example configuration, the UE has 4 transmit chains, each of which can be used to transmit a SRS resource. The UE can be configured to transmit 2 SRS resources simultaneously, each on a different transmit chain. The UE can be configured to transmit 4 SRS resources simultaneously, each on a different transmit chain. The UE can be configured to transmit 2 SRS resources simultaneously, each on a different transmit chain, and to transmit 2 SRS resources simultaneously, each on a different transmit chain. The UE can be configured to transmit 4 SRS resources simultaneously, each on a different transmit chain, and to transmit 4 SRS resources simultaneously, each on a different transmit chain. FIG. 5 ​In the example shown, since there are 4 unique beams per panel (assuming that each transmit chain in a panel uses the same 4 beam boresight as another transmit chain in the same panel), the UE can generate 8 unique beams. These unique beams are numbered 0 to 7 in the figure. Since the TRP can receive each beam at a different power level, the TRP should be informed of the total number of beams (or more generally, the effective antenna pattern) that the UE can generate. One way to do this is for the UE to indicate to the TRP that the UE can support (or alternatively require) 8 SRS resources as a UE capability. Typically, the number of SRS resources in the UE capability can reflect the case where the number of beams per panel is different, in which case the number of SRS resources is just the sum of all SRS resources required for each panel, i.e., the number of different beams that can be generated by each panel or the number required to provide sufficient angular coverage for the beams in that panel. In some cases, the UE can have overlapping beams across panels, so a given beam direction can be used in only one panel, and the total number of SRS resources in the UE capability will be the number of beams that are sufficiently non-overlapping.

[0095] To continue this example, let's assume that the UE is then configured with 8 SRS resources, each with 2 SRS ports, corresponding to each transmit chain in one of the panels. If the TRP wants the UE to transmit on all TX chains, it must know which SRS resources correspond to each TX chain. This can be equivalently identified, and the UE can use this identification to transmit the SRS resources simultaneously.

[0096] In an embodiment, applicable to the case where the UE supports only one beam per panel, the SRS resources that can be transmitted simultaneously are determined by a rule based on the number of SRS resources associated with each panel. In the two-panel example, the index is 0...N b The SRS resource of -1 is implicitly sent on panel #1, while the index is N b ...2*N b -1 SRS resources are applicable to panel #2, where N b is the number of beams (or equivalent SRS resources) per panel (and, in FIG. 5 In the example N b =4). More generally, the two panels have the same number of beams N b In the case of Then the TRP may assume that two SRS resource indices k1 and k2 can be sent simultaneously, for example in the same OFDM symbol. If more than one pair of SRS resources are to be sent simultaneously, the rule To determine whether all SRS resources can be sent simultaneously, where k i and k jare the ith and jth SRS resource indices to be paired, and all paired combinations of SRS resources to be transmitted simultaneously must satisfy this rule. SRS resources that cannot be transmitted together can be labeled as “SRS resource groups” or “SRS resource sets,” while the number N b may or alternatively be identified as the number of SRS resources in an SRS resource group or SRS resource set. Thus, for example, indices 0...N b -1 and N b ...2*N b -1 can be considered to be in the first and second SRS resource groups.

[0097] The SRS resource indices used to determine which SRS resources can be transmitted simultaneously or on the uplink can be different from the indices used to indicate how to transmit PUSCH using SRI. This is because the set of SRS resources that can be transmitted by a UE at any given point in time is typically larger than the number of SRS that a UE will be configured to use for PUSCH transmission. Configuring a UE to transmit PUSCH using a subset of all the SRS resources it can transmit allows for fewer SRI bits to be used to transmit that subset, rather than the entire possible set of SRS resources. Thus, in some embodiments, a UE is configured to have a first list of SRS resources corresponding to SRS resource indication (SRI) for PUSCH transmission, and a second list of SRS resources on which the UE can transmit SRS.

[0098] In some embodiments, the number of beams per panel can be different. Assuming panel k (or equivalent SRS resource group k) uses N b,k beams (or equivalent SRS resources), then SRS resources 0...N b,1 -1 are implicitly associated with panel #1 and cannot be transmitted simultaneously, while SRS resources N b,1 ,…,N b,1 +N b,2 -1 are associated with panel #2 and cannot be transmitted simultaneously, and so on.

[0099] In other embodiments, applicable to the case where different number of beams can be supported per panel UE, it is possible to configure for each panel which SRS resources can be transmitted simultaneously. A number of SRS resource lists are constructed, where each list includes a set of SRS resources that can not be transmitted simultaneously. All other combinations of SRS resources can be transmitted simultaneously. Each list of these SRS resources can correspond to beams in each panel that cannot be transmitted simultaneously, e.g., the analog beams selected for each panel. The lists do not have to be of the same length, or can also not have to identify the same number of beams that cannot be transmitted simultaneously, which allows for associating different number of beams with each list, and thus with each panel. In an embodiment, each list with index / includes a bitmap of length N b,max , and the bit with index m in list / corresponds to SRS resource k, where k = / N b,max + m and k, / and m are integers with minimum value zero. The number N b,max is alternatively identified as the maximum number of SRS resources in each SRS resource list, and each SRS resource list can be identified as a “SRS resource group” or “SRS resource set”.

[0100] Usage examples of these latter embodiments can be illustrated using the UE configuration below FIG. 7 , where panel #1 supports 4 beams and panel #2 has 2 beams. Two lists are needed (one per panel), where the first and second lists are denoted as {1111} and {1100}, respectively. SRS resources k e {0, 1, 2, 3} cannot be transmitted simultaneously and will be associated with the first list (and panel), while SRS resources k e {4, 5} cannot be transmitted simultaneously and will be associated with the second list (and panel),

[0101] In a variation of the previous embodiment, each list includes a bitmap of K max bits, where K max is the total number of SRS resources and each bit corresponds to one SRS resource. For the UE configuration in FIG. 7 , the two lists defining which resources can not be transmitted simultaneously are denoted by {111100} and {000011}, respectively.

[0102] In another variation of the previous embodiment connected to FIG. 7 , the signaling is done by signaling that resources can not be transmitted simultaneously {4, 2}, which means that SRS resources k e {0, 1, 2, 3} cannot be transmitted simultaneously, while SRS resources k e {4, 5} cannot be transmitted simultaneously. Thus, the order of this signaling can be important and used to label the individual SRS resources; the signaling {4, 2} can be translated into the following lists:

[0103] SRS resource index 0: panel 1, beam 0 within the panel,

[0104] SRS resource index 1: panel 1, beam 1 within the panel,

[0105] SRS resource index 2: panel 1, beam 2 within the panel,

[0106] SRS resource index 3: panel 1, beam 3 within the panel,

[0107] SRS resource index 4: panel 1, beam 0 within the panel,

[0108] SRS resource index 5: panel 1, beam 1 within the panel.

[0109] Thus, to indicate a certain beam, any gNB signaling can use this index. Based on the UE capability signaling {4, 2}, it also implicitly indicates the mapping of SRS resource indices to beams. For example, this mapping can clearly state that SRI ∈ {0, 1, 2, 3} corresponds to panel 1, while SRI ∈ {4, 5} corresponds to panel 2. For the more general case {N1, N2, …, Nq}, this means that SRS resource indices 0,.., N1-1 correspond to N1 beams from panel 1, the next N2 SRS resource indices correspond to N2 beams from panel 2, and so on.

[0110] In other embodiments, suitable for any SRS resource can be associated with any panel case, a list of all possible combinations of SRS resources of a given number of panels (or equivalent SRS resource groups, SRS resource group sets) is used to identify which combinations of SRS resources can be transmitted. The list of allowed SRS resource combinations is generated as a combination index r, which is defined as:

[0111]

[0112] where, is a set of length N p containing ordered SRS resource indices s i such that (1 ≤ s i ≤ N M，tot , S i < s i+1 ), where is the extended binomial coefficient, generating a unique label where N p is the number of SRS resources (or equivalently the number of panels, SRS resource sets, or SRS groups), N b,totis the total number of SRS resources allocated to the UE from which to choose for SRS transmission. Note that for clarity, the SRS resource index s i has a minimum value of 1 and a maximum value of N b while other embodiments have SRS indices that start from zero.

[0113] As mentioned above, a UE with UL MIMO capability can not be able to coherently transmit between some or all of its Tx chains, and the TRP should be aware of this limitation. In the simplest case, the UE is not able to coherently transmit between any group of its Tx chains. Such a UE can indicate that it is not able to coherently transmit on any combination of transmit chains. In an embodiment, when a UE with UL MIMO capability does not indicate that it can support relative phase continuity between Tx chains, an indication can be recognized that it is not able to coherently transmit on any transmit chain.

[0114] A UE can also support coherent transmission on Tx chains within a panel, but not across panels. In an embodiment, such a UE indicates which SRS resources can be coherently jointly transmitted by indicating whether the UE can coherently transmit PUSCH DMRS antenna ports corresponding to SRS resources in different SRS resource lists (or equivalently, different panels, SRS resource sets, or SRS groups) in addition to the PUSCH DMRS antenna ports corresponding to the SRS ports in each of its SRS resources. Such an indication can be that it supports relative phase continuity between all SRS resources corresponding to different SRS resource lists (or equivalently, different panels, SRS resource sets, or SRS groups).

[0115] In other cases, a UE can only be able to coherently transmit between some of its panels. Thus, in another embodiment, a UE indicates that in addition to the PUSCH DMRS antenna ports corresponding to the SRS ports in each of its SRS resources, the UE can also coherently transmit PUSCH DMRS antenna ports corresponding to SRS resources in a subset of SRS resource lists (or equivalently, a subset of panels, SRS resource sets, or SRS groups). Such an indication can be that it supports relative phase continuity between the set of SRS resource lists (or equivalently, different panels, SRS resource sets, or SRS groups). The set of SRS resource lists can be identified by a bitmap of coherent SRS resource lists, the length of which is N p where N pis the number of SRS resource lists (or equivalently, the number of panels, SRS resource sets, or SRS groups). For example, a “1” in the bitmap for a coherent SRS resource list indicates that all PUSCH DMRS ports associated with the SRS resources in the corresponding SRS resource list can be coherently transmitted with other DMRS ports associated with SRS resources in the coherent SRS resource list that also have a “1” in the bitmap. A “0” in the bitmap for a coherent SRS resource list indicates that all PUSCH DMRS ports associated with the SRS resources in the corresponding SRS resource list cannot be coherently transmitted with any other PUSCH DMRS port.

[0116] In some embodiments, the DCI format including the UL grant scheduling the PUSCH transmission is sized according to the indicated UE capability for SRS resources. For example, according to some embodiments, since SRS resources in a SRS resource list cannot be simultaneously transmitted, at most one SRS resource per SRS resource list (or equivalently, SRS group) can be indicated in the form of SRI in the DCI scheduling the PUSCH. Thus, in one embodiment, the SRI indication field includes N p subfields, where each subfield k = 1, …, N P includes bits. Each subfield is associated with a SRS resource list (or equivalently, SRS group) including N b,k SRS resources that cannot be simultaneously transmitted. Each codepoint in the bitfield indicates SRS resources in the list or no SRS resources in the list are used.

[0117] Uplink antenna subset transmission

[0118] When a UE is configured to be capable of transmitting using multiple SRIs, SRS resources can be associated with different Tx chains, and thus with subsets of UE antennas. If there are multiple SRS ports in a SRS resource, the TRP can use the SRS ports to determine a TPMI that identifies a precoder to be used on the antenna subset for PUSCH transmission. Thus, each SRS resource, and optionally each TPMI, will correspond to a different subset of UE antennas. Thus, in embodiments, when an SRI is transmitted to a UE, the UE transmits a physical channel such as a PUSCH on the UE antennas associated with the notified SRS resource using the precoder indicated by the TPMI.

[0119] In some embodiments supporting multiple SRIs, when the UE also indicates that each of the combination of SRS resources can be transmitted simultaneously and the multiple SRIs that the UE can transmit simultaneously are signaled, the UE transmits simultaneously on multiple subsets of its antennas. In some related embodiments, in the case that the UE can also coherently transmit PUSCH on the antennas corresponding to the SRS resources, a single TPMI can be transmitted to the UE that identifies a single precoder or precoder matrix to apply to the PUSCH on all of the antennas corresponding to the multiple SRIs informed to the UE. In other related embodiments in which the UE cannot coherently transmit PUSCH on the antennas corresponding to the SRS resources, the UE transmits different modulation symbols, and thus different MIMO layers, on different subsets of antennas corresponding to the informed SRIs. In similar embodiments in which the UE cannot coherently transmit, a single TPMI can be informed to the UE for each SRS resource that identifies a single precoder or precoder matrix to apply to the PUSCH on the subset of antennas corresponding to each of the multiple SRIs informed to the UE.

[0120] Uplink power control

[0121] Since different panels can point in different directions, the propagation environment they experience can be completely different. They can also be transmitting to different TRPs in a multi-TRP transmission. Therefore, in some embodiments of the invention, the UL power control is connected to the panel. Thus, going back to the previous embodiments in FIG. 7 of using analog beamforming on 4 transmit chains, each “panel” having 2 transmit chains, and the panels covering different directions, the UE can connect its power control to the panel. Thus, for example, if the power control is based on CSI-RS, the UE can be configured with two different CSI-RS, then the power control for panel 1 is based on CSI-RS1, while the power control for panel 2 is based on CSI-RS2. Since the path loss estimate for the power control depends on the panel, in this way, the open loop part of the power control will depend on the panel. Moreover, to do the power control, a set of parameters (a, P0, etc.) is usually configured, then they can be configured per panel based on the UE capability informed.

[0122] In other embodiments, two independent power control loops are used, but the path loss estimate is based on the same CSI-RS. In other embodiments, the path loss is instead based on a synchronization signal (SS).

[0123] In some embodiments, closed loop power control for each panel is accomplished by sending TPC commands per panel. In such cases, one or both of the SRS and PUSCH power sent from a panel can be used for uplink power measurements, and both SRS and PUSCH can have their transmit power controlled by TPC commands. Thus, power control commands for each panel can be associated with SRS resources, and in some embodiments, with SRS resource groups or lists.

[0124] In some related embodiments with per-panel power control, when multiple SRIs are indicated to the UE, it transmits using the power level corresponding to each power control command, which in turn corresponds to each SRS resource. Since SRS resources, groups, or lists can correspond to subsets of UE antennas, in the case of multiple SRIs being indicated, the power control commands can be used to set the power in different antenna subsets differently when transmitted simultaneously on different antenna subsets. This can bring the advantage of allowing different amplitude weighting of antenna elements even if the codebook associated with the TPMI has only unit magnitude weights. Such unequally weighted antenna arrays can have improved performance.

[0125] In some embodiments, each panel reports PHR (power headroom report).

[0126] FIG. 8 A block diagram of a wireless device 50 in a wireless communication system (e.g., a cellular communication system) in which embodiments of the disclosure can be implemented is shown. The wireless device 50 can be a UE. As used herein, the term “UE” broadly refers to any wireless device. Accordingly, the terms “wireless device” and “UE” can be used interchangeably herein. Generally, the wireless device 50 can additionally represent a target device, a D2D UE, a machine-type UE, or a UE capable of machine-to-machine (M2M) communication, a sensor equipped with a UE, an iPAD, a tablet, a mobile terminal, a smart phone, a laptop embedded equipment (LEE), a laptop mounted equipment (LME), a universal serial bus (USB) dongle, a customer premises equipment (CPE), an IoT (Internet of Things) enabled device, or any other device capable of communicating with a 5G and / or NR network, etc.

[0127] As FIG. 8As shown, wireless device 50 includes processing circuitry 52, which comprises one or more processors 62 (e.g., central processing units (CPUs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), and / or the like) and memory 64 that stores computer program 68 and, optionally, configuration data 68. Wireless device 50 also includes transceiver circuitry 56, which comprises one or more transmitters or receivers coupled to one or more antennas 54. In some embodiments, the functionality of wireless device 50 described above can be fully or partially implemented in software that is stored, e.g., in memory 64 and executed by processor 62.

[0128] In some embodiments, a carrier containing the computer program product described herein is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory).

[0129] In some embodiments, a computer program comprising instructions which, when executed by at least one processor, causes at least one processor of a wireless device 50 to carry out any of the UE-related techniques described herein.

[0130] Wireless device 50 (e.g., a UE) or a similar wireless device can be configured to, e.g., perform FIG. 9 the method 900 shown. Method 900 includes transmitting an indication that the UE can transmit a plurality of different RS resources, where each RS resource includes a plurality of RS ports (this is shown at block 902). Example method 900 also includes transmitting an indication of which RS resources the UE can transmit simultaneously, as shown at block 904, and receiving an indication of at least one RS resource, as shown at block 906. Note that transmitting an indication of which RS resources the UE can transmit simultaneously is a specific example of the UE transmitting capability information indicating that the UE 50 is capable of transmitting on multiple resources simultaneously.

[0131] In example method 900, which is not shown but is discussed above, the UE 50 can receive a first and second RS configuration from the network, e.g., where the first RS configuration is a first list of SRS resources corresponding at least to RS resource indications for PUSCH transmissions, and the second RS configuration is a second list of RS resources available for SRS transmissions. In various embodiments, this step can be an alternative to the steps shown in block 904, or an additional step.

[0132] Method 900 also includes transmitting a physical channel on the UE’s antennas associated with the indicated at least one RS resource, as shown at block 908.

[0133] In some embodiments, the method 900 further includes transmitting MIMO layers on different antenna subsets in the UE. In these embodiments, the method 900 further includes transmitting an indication that the UE is unable to control the relative phase between antenna ports on which it transmits when corresponding to different RS resources. The step of receiving the indication of at least one RS resource further includes receiving a plurality of RS resources and a precoder corresponding to each of the plurality of RS resources. The step of transmitting the physical channel includes using the indicated precoder on the UE’s antennas associated with each indicated RS resource.

[0134] The method 900 can further include receiving an indication of at least one precoder corresponding to each of the at least one RS resource and transmitting a physical channel on the UE’s antennas associated with the indicated RS resource using the indicated precoder.

[0135] The method 900 can include adjusting the transmission power of the plurality of RS resources, wherein the RS resources are transmitted simultaneously and the transmission power of each RS resource is adjusted by a power control command that is different from the power control commands adjusting the power of the other RS resources. In some embodiments, the method 900 can include adjusting the transmission power of the PUSCH corresponding to one or more RS resource indicators or adjusting the transmission power of one or more SRS resources corresponding to individual RS resource indicators or both, wherein the transmission power corresponding to each of the one or more RS resource indicators or each of the individual RS resource indicators is adjusted by a power control command that is different from the power control commands adjusting the transmission power corresponding to other RS resource indicators of the one or more RS resource indicators or the individual RS resource indicators.

[0136] In some embodiments, the UE is indicated a plurality of RS resources and the method 900 further includes transmitting a physical channel using a precoder on a plurality of antenna subsets corresponding to the plurality of indicated RS resources, the precoder jointly adjusting the phase of all RS ports included in the plurality of indicated RS resources.

[0137] FIG. 10is a block diagram illustrating an example network node 30 in a wireless communication system (e.g., a cellular communication system) in which embodiments of the disclosure can be implemented. The network node 30 can be a network access point, e.g., such as an eNB or gNB. In the illustrated example, the network node 30 is a radio access node, a transmission and reception point (TRP), a base station, or other general radio node that allows communication within a radio network. In various embodiments, the network node 30 can also represent, for example, a base transceiver station, a base station controller, a network controller, an enhanced or evolved NodeB (eNB), a NodeB, a gNB (an access point that supports NR or 5G), a multi-cell / multicast coordination entity (MCE), a relay node, an access point, a radio access point, or a remote radio unit (RRU) remote radio head (RRH). It will be understood that some of these examples do not include radio circuitry for communicating with UEs, but rather connect with one or more other network nodes via communication interface circuitry 38. In some embodiments, the network node 30 provides wireless access to other nodes (e.g., wireless devices 50 or other access nodes) within a coverage area of the network node 30 (e.g., a cell). The network node 30 described herein is configured to operate in an NR network, but can be applicable to other networks or standards using the techniques discussed herein.

[0138] As FIG. 10 illustrated, the network node 30 includes processing circuitry 32 including one or more processors 42 (e.g., CPUs, ASICs, FPGAs, etc.) and memory 44 storing computer program 46 and, optionally, configuration data 48. The network node 30 can include communication interface circuitry 38 for communicating with a core network or other network nodes. The illustrated network node 30 also includes transceiver circuitry 36, which can include one or more transmitters and receivers coupled to one or more antennas 34 for communicating with wireless devices (e.g., wireless devices 50). In some embodiments, the functionality of the network node 30 described herein can be fully or partially implemented in software that is, for example, stored in memory 44 and executed by processor(s) 42.

[0139] In some embodiments, the memory 44 of the network node 30 stores instructions that, when executed by the one or more processors 42, configure the network node 30 to perform one or more of the techniques described herein.

[0140] Whether operating alone or in conjunction with one or more other network nodes, the network node 30 can be configured to perform, for example, FIG. 11 illustrated methods and variations thereof. As FIG. 11As shown, the method 1100 includes receiving an indication of a plurality of different RS resources that the UE can transmit, where each RS resource includes a plurality of RS ports (shown at block 1102). The example method 1100 also includes receiving an indication of which RS resources the UE can transmit simultaneously, as shown at block 1104, and selecting at least one RS resource based on the received indication, as shown at block 1106. It will be understood that the indication of which RS resources the UE can transmit simultaneously is a specific example of more general UE capability information that indicates that the UE is capable of transmitting on multiple resources simultaneously.

[0141] Although not shown in the example method 1100, in some embodiments, the network node 30 can transmit, to the UE, a first and second RS configuration, where the first RS configuration is a first list of SRS resources corresponding to at least the RS resource indication for PUSCH transmission, and the second RS configuration is a second list of RS resources available for SRS transmission. In some embodiments, the network node 30 can transmit, to the UE, a transmission request, where the transmission request is structured by the network node 30 to avoid instructing the UE to transmit SRS resources that the UE is not capable of transmitting simultaneously, e.g., using capability information provided by the UE.

[0142] The method 1100 also includes transmitting, to the UE, an indication of the selected at least one RS resource, as shown at block 1108, and receiving a physical channel transmitted by the UE on the UE’s antennas associated with the indicated at least one RS resource, as shown at block 1110.

[0143] The method 1100 can also include receiving MIMO layers transmitted on different subsets of antennas in the UE, and receiving an indication that the UE is unable to control the relative phase between antenna ports when transmitting on the antenna ports corresponding to different RS resources. The step of transmitting the indication of the at least one RS resource can include transmitting a plurality of RS resources and a precoder corresponding to each of the plurality of RS resources. The received physical channel is transmitted on the UE’s antennas associated with each indicated RS resource using the indicated precoder.

[0144] The method 1100 can also include receiving an indication of at least one precoder corresponding to each of the at least one RS resource, and transmitting the physical channel on the UE’s antennas associated with the indicated RS resource using the indicated precoder.

[0145] The method 1100 can include transmitting, to the UE, a power control command for each of a plurality of RS resources of the UE, where the RS resources are transmitted simultaneously and the transmit power of each RS resource is adjusted by a power control command that is different from the power control command adjusting the other RS resources.

[0146] In some embodiments, the plurality of RS resources are indicated to the UE, and the method 1100 further includes receiving a physical channel transmitted using a precoder on a plurality of antenna subsets corresponding to the plurality of indicated RS resources, the precoder jointly adjusting phases of all RS ports included in the plurality of indicated RS resources.

[0147] Other embodiments of the inventive technology and apparatus disclosed herein include computer programs and computer program products containing instructions that, when executed by at least one processor of the wireless device 50, cause the at least one processor of the wireless device 50 to perform one or more of the above-described methods. Similarly, embodiments include computer programs and computer program products containing instructions that, when executed by at least one processor of the network node, cause the at least one processor of the network node 30 to perform one or more of the above-described methods for the network node 30.

[0148] The following provides context and additional details for supplementing the various techniques described above.

[0149] Some agreements on UL-MIMO codebook structure (e.g., from RAN1#88 and RAN1#88bis) include support for UL-MIMO scheduling by DCI for NR. This support can include an indication of SRI that the UE has transmitted in a previous time instance. Each configured SRS resource is associated with at least one UL Tx beam / precoder; no SRI is needed when a single SRS resource is configured. The support for UL-MIMO can also include a TRI taking values up to the number of SRS ports configured in the indicated SRI and a wideband TPMI. The TPMI is used to indicate the preferred precoder on SRS ports in the selected SRS resource by SRI. The precoding matrix can depend on the number of SRS ports configured in the indicated SRI. This field can be used for non-codebook-based UL-MIMO transmission and can signal subband TPMI. There can be multiple ways to indicate the selection of multiple SRS resources.

[0150] When a UE is configured with UL frequency-selective precoding and if subband TPMI signaling is supported, one of the following alternative methods can be supported: 1) subband TPMI is transmitted to the UE via DCI only for the allocated PRBs of a given PUSCH transmission; or 2) subband TPMI is transmitted to the UE via DCI for all PRBs in the UL, regardless of the actual RA of a given PUSCH transmission. If a two-stage codebook is supported, the subband TPMI can correspond to W2. Wideband TPMI can always be transmitted together with subband TPMI.

[0151] Furthermore, there can be a predetermined minimum number of X and Y ports and definitions for supporting frequency selective precoding for multiple schemes (e.g., schemes A and B). For this protocol, scheme A is a codebook-based UL transmission related to previous protocols involving support of frequency selective precoding for CP-OFDM when the number of transmission ports is equal to or greater than X. Scheme B is a non-codebook-based UL transmission involving support of frequency selective precoding for CP-OFDM when the number of transmission ports is equal to or greater than Y.

[0152] The main difference between the codebook-based UL transmission scheme and the non-codebook-based UL transmission scheme in NR is that for codebook-based UL transmission, a TPMI is sent to the UE, while for non-codebook-based UL transmission, no TPMI is sent. Another difference is that for codebook-based UL transmission, the power amplifier (PA) is not intended (not allowed) to be mapped to more than one SRS port in order to preserve the utilization of the power amplifier when other precoding is applied on the SRS port. On the other hand, for non-codebook-based UL transmission, the PA is intended (allowed) to be mapped to multiple SRS ports because no other precoding is applied on the SRS port.

[0153] In some embodiments, for codebook-based UL transmission, at least one TPMI is sent back to the UE to determine the precoder for UL transmission. In other embodiments, for non-codebook-based UL transmission, no TPMI is sent back to the UE. Instead, an SRI can be sent back to the UE to determine the precoder for UL transmission.

[0154] The main driver of TPMI overhead is whether to support wideband or frequency selective TPMI. TPMI overhead can be reasonably carried in PDCCH and can determine the upper limit of the gain that can be obtained from frequency selective precoding.

[0155] The signaling to support codebook-based frequency selective precoding is fundamentally different on the uplink and downlink. In the downlink, TPMI signaling can be avoided because the UE can determine the effective channel by measuring the DMRS. However, in codebook-based UL MIMO, the UE must be aware of the precoding required by the gNB and therefore must be sent through TPMI.

[0156] A second distinction between uplink and downlink precoding is that the UCI payload can have multiple sizes, while the UE is only configured with a small number of DCI formats with fixed sizes. Thus, the PMI for DL MIMO can have multiple sizes, while the TPMI for UL MIMO should preferably have a fixed size. Note that a two-stage DCI signaling can carry additional overhead, but such a two-stage design would typically complicate the NR control signaling significantly and can not be preferred in at least the first release of NR.

[0157] Another distinction is that the UCI can be carried on multiple PUCCH formats and PUSCH, which allows the UCI to be adapted according to coverage requirements. While the PDCCH supports compact and larger DCI formats to allow for different coverage conditions, the flexibility is much reduced.

[0158] Another observation is that the NR PDCCH should have similar coverage as the LTE PDCCH, so the format sizes should be similar. This can be used as a rough guideline for the TPMI size for NR UL MIMO. Note that up to 6 bits are used for 4Tx precoding and rank indication, and 5 bits for the MCS of the second transport block, with 1 bit for the new data indicator. Thus, relative to LTE, there will be a consistent amount of overhead for all TPMI, SRI, and RI, in terms of UL MIMO operation.

[0159] It has been observed that around 10 DCI bits for all TPMI, SRI, and RI can be used as a starting point for the NR UL MIMO codebook design.

[0160] The performance of wideband and subband TPMI will now be discussed. The number of bits required for frequency-selective TPMI tends to scale with the number of subbands. In this section, advanced simulation results obtained by the inventors are presented comparing the ideal array gain for transmissions based on 1st order subband TPMI with the ideal array gain using wideband transmissions. The upper and lower bound performance is evaluated by ideal closed-loop (CL) MIMO based on SVD of the subband-dependent matrix and ideal transmit diversity (TXD) schemes. To make the performance comparison, the Rel-8 codebook and an example codebook are evaluated using non-constant modulus elements. 1st order precoding is used as this is where the maximum gain tends to be, and thus can be used as a preliminary check on the advantages of subband TPMI. The figures shown in FIG. 12-15 are obtained by modeling the single link using channels with 3GPP evaluation assumptions extracted from a system level simulator. Thus, system level considerations (e.g., inter-UE interference) are not captured in the performance comparison. Ideal channel estimation is used. Thus, the results can be considered as an upper bound on the gain of frequency-selective precoding. FIG. 12-15Simulation results are shown for a UE equipped with multiple panels. Two (four) UE antennas are implemented as two (four) single-port panels to transmit signals from different angles, i.e., azimuth angles of 0 and 180 degrees (0, 90, 180, and 270 degrees).

[0161] FIG. 12-13 Evaluation results are shown for 1 -stage transmission on 2 single-port panels with 10MHz channel bandwidth at 28GHz frequency. In these simulations, three different subband sizes are compared, i.e., in addition to wideband transmission, each subband has 1 PRB and 12 PRBs, respectively, assuming a total of 48 PRBs, which are grouped in the figure with ellipses as different curves.

[0162] From these results, it is observed that up to 0.4dB (maximum, basically theoretically) gain can be achieved by TPMI-based subband transmission with 1 PRB per subband compared to wideband transmission. A more practical number of subbands (e.g., 4 subbands) yields a median gain of about 0.15dB.

[0163] A comparison of codebooks can show that the example codebook tends to be significantly better than the Rel-8 codebook, with a median gain of typically about 1.0dB. Even the Rel-8 codebook with more bits (per subband TPMI), the wideband example codebook with 3 bits of overhead is actually better than the Rel-8 codebook. Since the example codebook is expected to have a large gain due to the use of non-constant modulus elements, it can be concluded that a larger codebook with non-constant modulus elements can be a better solution than using more subbands with Rel-8 (constant modulus) codebooks. This is especially true for mmWave cases, since the directionality of different panels can cause a large variation in received power levels from the panels at the gNB.

[0164] FIG. 12 and FIG. 13 Performance comparisons in terms of achievable channel gain between different transmission schemes and different codebooks are shown for 1 -stage transmission over 2 single-port panels at 28GHz frequency.

[0165] FIG. 14 and FIG. 15 Performance comparisons in terms of achievable channel gain between different transmission schemes and different codebooks are shown for 1 -stage transmission over 4 single-port panels at 28GHz frequency. FIG. 14 and 15Simulation results are provided for 1-level transmission with 4 one-port panels. Similar observations can be made for the 4 one-port panels. In particular, the gain from the actual number of subbands in frequency-selective precoding is again in the tenths of dB. However, since the 4-port codebook is larger than the 2-port codebook, the TPMI overhead for 4-port subband precoding to achieve the same gain as 2-port subband precoding is much larger. Therefore, the impact of subband TPMI for 4 ports appears to be less than for 2 ports.

[0166] It has been observed that the gain of subband TPMI with actual number of bits in the actual channel can be modest. For example, for 2 and 4 ports at 28 GHz, it has been observed that the median gain for UMa is about 0.15-0.3 dB. It has also been observed that increasing the codebook size and using non-constant modulus elements can provide substantially better gain than increasing the subband size in a multi-panel UE.

[0167] Based on the simulation results presented in this contribution, in some embodiments, subband TPMI can be needed. The value of X can not be determined by the UL MIMO subband precoding gain. Codebooks with non-constant modulus can be considered as an alternative to subband TPMI for UL MIMO.

[0168] With respect to antenna element radiation patterns, polarization characteristics, antenna element spacing, and pointing directions, the antenna array topology of a UE is expected to be quite arbitrary. For UE implementations, especially at higher frequencies, it can be expected that different antenna placements within a UE (where each antenna placement (e.g., a single antenna element or panel) is assumed to be connected to one baseband port) will experience low or no correlation in the channel due to, for example, radiation patterns pointing in different directions, large spacing between antenna devices, or orthogonal polarizations. This is not to say that a simple i.i.d. model is suitable. Rather, an evaluation of the real channel and models for these various UE configurations is needed to produce a robust codebook.

[0169] Therefore, it is desirable to create a codebook that works well under a variety of UE antenna configurations and channel conditions. A DL DFT-based codebook with uniformly spaced antenna elements, where the codebook is based on a uniform linear array of antenna elements or subarrays, can not be sufficient for UEs.

[0170] It has been observed that to support full UE antenna implementation freedom, NR codebooks should be designed considering a variety of UE antenna configurations and channel conditions.

[0171] Furthermore, the UL codebook design can be optimized in multiple ways. Since the uplink supports both DFT-S-OFDM and CP-OFDM, the codebook can be designed for both sets of waveforms. Depending on the amount of UL overhead that can be tolerated and the channel conditions, a multi-stage or single-stage codebook can be supported. A cubic metric preserving codebook or a codebook with non-constant modulus elements can be configured to allow some potential power saving versus performance tradeoff, etc. Thus, it can be desirable to start with a simple, robust design as a baseline and add codebooks one by one after determining their performance gain, complexity benefit, and use cases.

[0172] The optimization should keep in mind the use cases of UL MIMO. The primary target of multiple Tx chains in a UE is typically SU-MIMO since it allows higher peak rates that end users can benefit from. The gain in system capacity is more likely to come from uplink sectorization and / or MU-MIMO since gNBs tend to have more (perhaps much more) receive antennas. If multiple Tx antennas are a UE capability, it is not possible to set cell coverage based on multiple Tx antennas, and thus, multiple UE antennas are typically not an effective way to increase range. Therefore, the design should focus as much as possible on getting the most "bang for the buck" out of the DCI bits and use simple schemes.

[0173] It is observed that multiple codebooks can be designed for CP-OFDM versus DFT-S-OFDM, CM preserving versus non-constant modulus, single-stage versus multi-stage, etc. Thus, it can be desirable to prioritize designing robust, simple codebooks as a baseline and add other codebooks depending on the gain, complexity, and use cases.

[0174] It is not yet determined whether 8-port SRS is supported. As mentioned above, the UL MIMO design is primarily driven by peak rates. NR needs to achieve 15 bps / Hz peak spectral efficiency on the uplink, and this can be met by four 64QAM MIMO layers with a coding rate of 5 / 8 per layer. Thus, it does not seem that 8 MIMO layers are needed, nor a codebook to support 8 SRS ports, at least in the first release of NR. Note that forward compatibility should be kept in mind, and thus, even if Release 15 NR does not support 8 MIMO layers, it can be desirable to have 8 DMRS and 8 SRS ports in Release 15. It has been observed that 4-layer SU-MIMO can meet the NR peak spectral efficiency requirement of 15 bps / Hz. Release 15 NR can support up to 4 layers for SU-MIMO transmission and codebook.

[0175] Since the assumption is that different antennas at the UE are expected to have low correlation at least in some UE implementations, a two-stage codebook (i.e., a W = W1W2 structure as defined for LTE downlink) can not be sufficient as this structure is tailored specifically for separating wideband (and possibly slowly varying) and subband behavior. Moreover, a 2 SRS port codebook would be single stage only.

[0176] However, in a UE configuration and with a large number of SRS ports, if the channel shows sufficient correlation, this approach can be utilized to reduce feedback as done by a two-stage codebook. In some embodiments, the UL codebook can include a two-stage structure. It has been observed that a single stage codebook structure can be needed to handle low channel correlation. In some embodiments, a multi-stage codebook structure (e.g., W = W1W2 as in DL) can be used to reduce overhead if the channel correlation allows.

[0177] The two alternatives from RANI #88bis have a fundamental impact on whether the TPMI persists over time. In alternative 1, the subband TPMI can be sent to the UE via DCI only for the PRBs allocated for a given PUSCH transmission. In alternative 2, the subband TPMI can be sent to the UE via DCI for all PRBs in the UL regardless of the actual RA of a given PUSCH transmission.

[0178] In alternative 1, the TPMI is only applicable to the PUSCH transmission. This means that there is no inter-dependence or accumulation of TPMI between subframes, i.e., the TPMI is a “single shot”. Allowing the TPMI to be persistent can be used to reduce overhead, e.g., in a multi-stage codebook, the long-term “W1” is transmitted less frequently than the short-term “W2”. Similarly, different TPMIs in different subframes can be applicable to different subbands. However, whether or how much overhead can be saved depends on the channel characteristics and how many PUSCH transmissions the UE makes.

[0179] Furthermore, TPMI is only applied to PUSCH, not to other signals (e.g., SRS). This is in contrast to Alternative 2, which allows precoded SRS controlled by TPMI. Because the eNB knows the TPMI and has unprecoded SRS or DMRS, the eNB should be able to determine the composite channel after precoding and there is no benefit from, e.g., interference estimation or power control perspective. Furthermore, multiple SRS resources can be used to track the beamforming gain of the Tx chain. TPMI can control SRS precoding. Finally, it is unclear whether Alternative 2 is applicable outside of the bandwidth part. In some embodiments, at least wideband TPMI and single-stage codebook support a variant of Alternative 1 from RANI #88bis: TPMI is sent to the UE via DCI only for the PRBs allocated for a given PUSCH transmission.

[0180] In some embodiments, the codebook that can be used for codebook-based UL transmission contains only port-combining precoders (i.e., no port-selection precoders, as this can be handled via SRI), in order to minimize the size of the codebook and thus reduce overhead signaling.

[0181] Since NR can support only a limited number of ports in the codebook, while the number of SRS resources will be more flexible, it is advantageous to use SRI instead of codebook for port selection. It has been observed that SRI can be used for UE Tx antenna selection without increasing the TPMI overhead. In some embodiments, the codebook used for codebook-based UL transmission should contain only port-combining precoders.

[0182] Since antenna directional patterns, orientations, and polarization behavior can vary greatly in UEs, it can not be practical to develop models specifically for multi-panel UEs. However, a codebook design that supports uncorrelated elements can provide benefits in a variety of antenna configurations. Thus, a sufficiently robust single-panel design can be used in a multi-panel situation. It has been observed that a robust single-panel design can be used for multi-panel applications. In some embodiments, the UL codebook design is targeted for single-panel operation, and multi-panel operation can be supported with a single-panel design.

[0183] It is natural to send different panels on different SRS resources, since the spatial characteristics of the elements in the panel can vary between panels. However, it can also be beneficial to send on multiple panels simultaneously to produce a higher rank, more directional transmission, and / or to combine transmit power from multiple power amplifiers. Thus, it should be possible to form a port on which a codebook can be applied by pooling SRS resources. When multiple SRIs are indicated, the TPMI is applied on all ports in the indicated resources, and a codebook corresponding to the pooled resources is used. In some embodiments, TPMI can be applied to pooled SRS resources indicated by multiple SRIs.

[0184] Concepts are currently being developed for NR for UL beam management to control the beams (or more precisely the effective antenna patterns) of individual UE panels. It is expected that UL beam management is performed by having the UE transmit different SRS resources in different UE panel beams, for which the TRP performs RSRP measurements and sends back the SRI corresponding to the SRS resource with the highest RSRP value. If a multi-panel UE is scheduled for SRS transmission from multiple beams of each of multiple panels, the TRP and the UE need to have a common agreement on which combinations of SRS resources can be transmitted simultaneously from different panels. Otherwise, for example, when the SRS resources correspond to different switched analog beams in the panels, the TRP can select SRS resources that cannot be transmitted simultaneously. One way to solve this problem is to identify groups of SRS resources, where only one resource in a group of SRS resources can be transmitted at a time. One resource in each group of SRS resources can be transmitted simultaneously with each of the other selected SRS resources in the other groups. Knowing the number of SRS groups and which SRS resources are in the groups, the TRP can determine which SRS resources the UE can be instructed to transmit when multiple SRIs are sent.

[0185] Note that the concept of SRS resource groups here is similar in purpose to the DMRS port groups defined for NR downlink and to the SRS port groups. Assume that SRI refers to SRS resources, and since SRS antenna port groups seem to imply some selection or subdivision within one SRS resource, "SRS resource groups" seems more appropriate to describe the intended behavior.

[0186] In some embodiments, SRS resource groups can be defined, where it can be assumed that the UE can only transmit one SRS resource in one SRS resource group at a time, and where the UE can transmit one SRS resource from each of multiple SRS resource groups simultaneously.

[0187] Various issues related to UL MIMO codebooks have been explored, including the definition of codebook-based and non-codebook-based UL transmissions, the design of UL MIMO codebooks, the amount of TPMI overhead that can be used to support them, the benefit of frequency-selective precoding, whether TPMI should be persistent, and the number of ports and layers that UL SU-MIMO and codebooks should be designed for. It has been observed that about 10 DCI bits for all TPMI, SRI, and RI can be used as a starting point for NR UL MIMO codebook design; and that the gain from subband TPMI with actual bits in the actual channel can not be large. For example, for 2 and 4 ports at 28 GHz, the median gain that has been observed in UMa is about 0.15-0.3 dB.

[0188] It has also been observed that increasing the codebook size and using non-constant modulus elements can provide substantially better gains compared to increasing the subband size in multi-panel UEs. To support full UE antenna implementation freedom, the NR codebook should be designed considering multiple UE antenna configurations and channel conditions. It has been observed that multiple codebooks can be designed for CP-OFDM vs. DFT-S-OFDM, CM preservation vs. non-constant modulus, single-stage vs. multi-stage, etc. It has been observed that 4-layer SU-MIMO can meet the NR peak spectral efficiency requirement of 15 bps / Hz. Single-stage codebook structure can be needed to handle low channel correlation.

[0189] It has also been observed that SRI can be used for UE Tx antenna selection without increasing the TPMI overhead, and a robust single-panel design can be used for multi-panel applications.

[0190] In some embodiments, for codebook-based UL transmission, at least TPMI is fed back to the UE to determine the precoder for UL transmission. For non-codebook-based UL transmission, no TPMI is fed back to the UE, but SRI is fed back to the UE to determine the precoder for UL transmission. In some cases, subband TPMI can be used.

[0191] In some embodiments, the value of X is not determined by the UL MIMO subband precoding gain. Codebooks with non-constant modulus can be considered as an alternative to subband TPMI for UL MIMO.

[0192] In some embodiments, a robust, simple codebook can be prioritized for design as a baseline, and other codebooks can be added according to gain, complexity, and use cases. Release 15 NR can support up to 4 layers for SU-MIMO transmission and codebook. If channel correlation allows, a multi-stage codebook structure (e.g., using W = W1W2 as in DL) can be used to reduce overhead.

[0193] In some embodiments, at least wideband TPMI and single-stage codebook support a variant of Alternative 1 from RANI #88bis: TPMI is sent to the UE via DCI only for the PRBs allocated for a given PUSCH transmission. In some cases, the codebook for codebook-based UL transmission should contain only port combination precoders.

[0194] UL codebook design can be for single-panel operation, and single-panel design can support multi-panel operation.

[0195] A TPMI can be applied to a summarized SRS resource indicated by multiple SRIs. SRS resource groups can be defined, where it can be assumed that a UE can only transmit one SRS resource in one SRS resource group at a time, and where the UE can transmit one SRS resource from each of multiple SRS resource groups at the same time.

[0196] FIG. 16 is a schematic block diagram of a wireless device 50 according to some other embodiments of the present disclosure. The node includes one or more modules, each of which is implemented in software. These modules provide the functionality of a wireless device according to any of several UE-related techniques described herein, and include an indication transmitting module 1602 for transmitting an indication that a UE can transmit multiple different RS resources, where each RS resource includes multiple RS ports; and for transmitting an indication of which RS resources the UE can transmit on at the same time. The illustrated wireless device 50 also includes an indication receiving module 1604 for receiving an indication of at least one RS resource; and a physical channel transmitting module 1606 for transmitting a physical channel on the UE's antenna associated with the indicated at least one RS resource.

[0197] Similarly, FIG. 17 is a schematic block diagram of a network node according to some other embodiments of the present disclosure. The node includes one or more modules, each of which is implemented in software. According to some embodiments, these modules provide the functionality of a network node, and include an indication receiving module 1702 for receiving an indication that a UE can transmit multiple different RS resources, where each RS resource includes multiple RS ports; and for receiving an indication of which RS resources the UE can transmit on at the same time; and a selecting module 1704 for selecting at least one RS resource based on the received indications. The illustrated network node 30 also includes a transmitting module 1706 for transmitting an indication of the selected at least one RS resource to the UE; and a physical channel receiving module 1708 for receiving a physical channel transmitted by the UE on the UE's antenna associated with the indicated at least one RS resource.

[0198] It should be noted that modifications and other embodiments of the disclosed implementations are possible, and thus, the foregoing description is intended for purposes of illustration only and should not be construed as limiting the scope of the disclosure. Although specific terms can be employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

[0199] Embodiments of the technology and apparatus disclosed above include, but are not limited to, the following examples:

[0200] (a) In a UE, a method of transmitting on different subsets of antennas in the UE, the method comprising:

[0201] transmitting an indication that the UE can transmit a plurality of different RS resources, wherein each RS resource comprises a plurality of RS ports;

[0202] transmitting an indication of which RS resources the UE can transmit on simultaneously;

[0203] receiving an indication of at least one RS resource;

[0204] transmitting a physical channel on the antennas of the UE associated with the indicated at least one RS resource.

[0205] (b) The method of example embodiment (a), wherein the method further comprises transmitting MIMO layers on different subsets of antennas in the UE, wherein:

[0206] the method further comprises transmitting an indication that the UE is unable to control the relative phase between antenna ports on which it transmits corresponding to different RS resources;

[0207] the step of receiving an indication of at least one RS resource further comprises receiving a plurality of RS resources and a precoder corresponding to each of the plurality of RS resources; and

[0208] the step of transmitting a physical channel comprises using the indicated precoder on the antennas of the UE associated with each indicated RS resource.

[0209] (c) The method of example embodiment (a) or (b), further comprising:

[0210] receiving an indication of at least one precoder corresponding to each of the at least one RS resource;

[0211] transmitting the physical channel on the antennas of the UE associated with the indicated RS resource using the indicated precoder.

[0212] (d) The method of any of example embodiments (a)-(c), further comprising adjusting the transmit power of a plurality of RS resources, wherein the RS resources are transmitted simultaneously and the transmit power of each RS resource is adjusted by a power control command that is different from the power control commands that adjust the power of the other RS resources.

[0213] (e) The method of any of example embodiments (a)-(d), wherein the UE is indicated of multiple RS resources, and the method further comprises transmitting a physical channel using a precoder that jointly adjusts phases of all RS ports included in the multiple indicated RS resources on multiple antenna subsets corresponding to the multiple indicated RS resources.

[0214] (F) A method of receiving, in a network node of a wireless network, transmissions from a UE on different antenna subsets of the UE, the method comprising:

[0215] receiving an indication that the UE can transmit multiple different RS resources, wherein each RS resource includes multiple RS ports;

[0216] receiving an indication of which RS resources the UE can transmit on simultaneously;

[0217] selecting at least one RS resource based on the received indications;

[0218] transmitting an indication of the selected at least one RS resource to the UE;

[0219] receiving a physical channel transmitted by the UE on antennas of the UE associated with the indicated at least one RS resource.

[0220] (g) The method of example embodiment (f), wherein the method further comprises receiving MIMO layers transmitted on different antenna subsets in the UE, wherein:

[0221] the method further comprises receiving an indication that the UE is unable to control relative phases between antenna ports on which the UE transmits corresponding to different RS resources;

[0222] the step of transmitting an indication of at least one RS resource comprises transmitting multiple RS resources and a precoder corresponding to each of the multiple RS resources; and

[0223] transmitting the received physical channel using the indicated precoder on antennas of the UE associated with each indicated RS resource.

[0224] (h) The method of example embodiment (f) or (g), further comprising:

[0225] receiving an indication of at least one precoder corresponding to each of the at least one RS resource;

[0226] transmitting the physical channel using the indicated precoder on antennas of the UE associated with the indicated RS resource.

[0227] (i) The method of any of example embodiments (f)-(h), further comprising: transmitting, to the UE, a power control command for each of a plurality of RS resources of the UE, wherein the RS resources are transmitted simultaneously, and the transmit power of each RS resource is adjusted by the power control command, which is different from the power control commands that adjust the other RS resources.

[0228] (j) The method of any of example embodiments (f)-(i), wherein a plurality of RS resources are indicated to the UE, and the method further comprises: receiving a physical channel transmitted using a precoder on a plurality of antenna subsets corresponding to the plurality of indicated RS resources, the precoder jointly adjusting the phase of all RS ports included in the plurality of indicated RS resources.

[0229] (k) A UE adapted to transmit on different antenna subsets in the UE, the UE adapted to:

[0230] transmit an indication that a plurality of different RS resources can be transmitted by the UE, wherein each RS resource includes a plurality of RS ports;

[0231] transmit an indication of which RS resources the UE can transmit on simultaneously;

[0232] receive an indication of at least one RS resource;

[0233] transmit a physical channel on the UE's antennas associated with the indicated at least one RS resource.

[0234] (l) The UE of example embodiment (k), wherein the UE is further adapted to transmit MIMO layers on different antenna subsets in the UE, wherein:

[0235] the UE is adapted to provide an indication that the UE is unable to control the relative phase between antenna ports when transmitting on the antenna ports corresponding to different RS resources;

[0236] the UE is adapted to receive a plurality of RS resources and a precoder corresponding to each of the plurality of RS resources; and

[0237] the UE is adapted to transmit a physical channel on the UE's antennas associated with each indicated RS resource using the indicated precoder.

[0238] (m) The UE of example embodiment (k) or (1), wherein the UE is further adapted to:

[0239] receive an indication of at least one precoder corresponding to each of the at least one RS resource; and

[0240] transmit a physical channel using the indicated precoder on the UE's antennas associated with the indicated RS resource.

[0241] (n) The UE of any of example embodiments (k)-(m), wherein the UE is further adapted to adjust the transmit power of the plurality of RS resources, wherein the RS resources are transmitted simultaneously, and adjust the transmit power of each RS resource with a power control command that is different from the power control commands that adjust the power of the other RS resources.

[0242] (o) The UE of any of example embodiments (k)-(n), wherein the UE is indicated a plurality of RS resources, the UE is further adapted to transmit a physical channel using a precoder on a plurality of subsets of antennas corresponding to the plurality of indicated RS resources, the precoder jointly adjusts the phase of all RS ports included in the plurality of indicated RS resources.

[0243] (p) A network node of a wireless network adapted to receive transmissions from a UE on different subsets of antennas of the UE, wherein the network node is adapted to:

[0244] receive an indication that the UE can transmit a plurality of different RS resources, wherein each RS resource includes a plurality of RS ports;

[0245] receive an indication of which RS resources the UE can transmit on simultaneously;

[0246] select at least one RS resource based on the received indications;

[0247] transmit an indication of the selected at least one RS resource to the UE;

[0248] receive a physical channel transmitted by the UE on the UE's antennas associated with the indicated at least one RS resource.

[0249] (q) The network node of example embodiment (p), wherein the network node is adapted to receive MIMO layers transmitted on different subsets of antennas in the UE, wherein the network node is adapted to:

[0250] receive an indication that the UE is unable to control the relative phase between antenna ports when transmitting on the antenna ports corresponding to different RS resources; and

[0251] transmit a plurality of RS resources and a precoder corresponding to each of the plurality of RS resources to the UE; and

[0252] wherein the received channel is transmitted by the UE using the indicated precoder on the UE's antennas associated with each indicated RS resource.

[0253] (r) The network node of example embodiment (p) or (q), wherein the network node is further adapted to:

[0254] receive an indication of at least one precoder corresponding to each of the at least one RS resource;

[0255] transmit a physical channel on the UE’s antennas associated with the indicated RS resource using the indicated precoder.

[0256] (s) The network node of any of example embodiments (p)-(r), wherein the network node is further adapted to: transmit to the UE a power control command for each of a plurality of RS resources of the UE, wherein the RS resources are transmitted simultaneously and the transmit power of each RS resource is adjusted by a power control command that is different from the power control command adjusting the power of the other RS resources.

[0257] (t) The network node of any of example embodiments (p)-(s), wherein the plurality of RS resources are indicated to the UE, wherein the received physical channel is transmitted by the UE using a precoder on a plurality of antenna subsets corresponding to the plurality of indicated RS resources, the precoder jointly adjusting the phase of all RS ports included in the plurality of indicated RS resources.

[0258] (u) A UE adapted to transmit on different antenna subsets in the UE, the UE comprising:

[0259] transceiver circuitry;

[0260] a processor operably coupled to the transceiver circuitry; and

[0261] a memory coupled to the processing circuitry, the memory storing instructions executed by the processor such that the processor is configured to control the transceiver circuitry to:

[0262] transmit an indication that the UE can transmit a plurality of different RS resources, wherein each RS resource includes a plurality of RS ports;

[0263] transmit an indication of which RS resources the UE can transmit on simultaneously;

[0264] receive an indication of at least one RS resource;

[0265] transmit a physical channel on the UE’s antennas associated with the indicated at least one RS resource.

[0266] (v) The UE of example embodiment (u), wherein the processor is configured to transmit MIMO layers on different antenna subsets in the UE, wherein:

[0267] the processor is configured to transmit an indication that the UE is unable to control the relative phase between the antenna ports when the UE transmits on the antenna ports corresponding to different RS resources;

[0268] the processor is configured to receive a plurality of RS resources and a precoder corresponding to each of the plurality of RS resources; and

[0269] the processor is configured to transmit a physical channel on the UE’s antennas associated with each indicated RS resource using the indicated precoder.

[0270] (w) the UE of example embodiment (u) or (v), wherein the processor is configured to:

[0271] receive an indication of at least one precoder corresponding to each of the at least one RS resource; and

[0272] transmit a physical channel on the UE’s antennas associated with the indicated RS resource using the indicated precoder.

[0273] (x) the UE of any of example embodiments (u)-(w), wherein the processor is configured to adjust the transmit power of the plurality of RS resources, wherein the RS resources are transmitted simultaneously and the transmit power of each RS resource is adjusted by a power control command that is different from the power control command that adjusts the power of the other RS resources.

[0274] (y) the UE of any of example embodiments (u)-(x), wherein the UE is indicated the plurality of RS resources, the processor is further configured to transmit a physical channel on a plurality of subsets of antennas corresponding to the plurality of indicated RS resources using a precoder that jointly adjusts the phase of all RS ports included in the plurality of indicated RS resources.

[0275] (z) a network node of a wireless network adapted to receive transmissions from a UE on different subsets of antennas of the UE, the network node comprising:

[0276] transceiver circuitry;

[0277] a processor operably coupled to the transceiver circuitry; and

[0278] a memory coupled to the processing circuitry, the memory storing instructions executed by the processor such that the processor is configured to control the transceiver circuitry to:

[0279] receive an indication that the UE can transmit a plurality of different RS resources, wherein each RS resource includes a plurality of RS ports;

[0280] receiving an indication of which RS resources the UE can transmit on simultaneously;

[0281] selecting at least one RS resource based on the received indication;

[0282] sending an indication of the selected at least one RS resource to the UE;

[0283] receiving a physical channel transmitted by the UE on the UE’s antennas associated with the indicated at least one RS resource.

[0284] (aa) The network node of example embodiment (z), wherein the processor is configured to receive MIMO layers transmitted on different subsets of antennas in the UE, wherein the processor is configured to:

[0285] receive an indication that the UE is unable to control the relative phase between antenna ports when transmitting on the antenna ports corresponding to different RS resources; and

[0286] sending a plurality of RS resources and a precoder corresponding to each of the plurality of RS resources to the UE; and

[0287] wherein the received channel is transmitted by the UE using the indicated precoder on the UE’s antennas associated with each indicated RS resource.

[0288] (bb) The network node of example embodiment (z) or (aa), wherein the processor is configured to:

[0289] receive an indication of at least one precoder corresponding to each of the at least one RS resource;

[0290] transmit a physical channel using the indicated precoder on the UE’s antennas associated with the indicated RS resource.

[0291] (cc) The network node of any of example embodiments (z)-(bb), wherein the processor is configured to send a power control command to the UE for each of a plurality of RS resources of the UE, wherein the RS resources are transmitted simultaneously and the transmit power of each RS resource is adjusted by a power control command that is different from the power control command that adjusts the power of the other RS resources.

[0292] (dd) The network node of any of example embodiments (z) - (cc), wherein the UE is indicated of a plurality of RS resources, wherein the received physical channel is transmitted by the UE using a precoder that jointly adjusts phases of all RS ports included in the plurality of indicated RS resources on a plurality of antenna subsets corresponding to the plurality of indicated RS resources.

[0293] (ee) A UE adapted to transmit on different antenna subsets in the UE, the UE comprising:

[0294] an indication transmitting module for transmitting an indication that the UE can transmit a plurality of different RS resources, wherein each RS resource includes a plurality of RS ports, and for transmitting an indication of which RS resources the UE can transmit on simultaneously;

[0295] a receiving module for receiving an indication of at least one RS resource; and

[0296] a physical channel transmitting module for transmitting a physical channel on an antenna of the UE associated with the indicated at least one RS resource.

[0297] (ff) A network node of a wireless network adapted to receive transmissions from a UE on different antenna subsets in the UE, the network node comprising:

[0298] an indication receiving module for receiving an indication that the UE can transmit a plurality of different RS resources, wherein each RS resource includes a plurality of RS ports, and for receiving an indication of which RS resources the UE can transmit on simultaneously;

[0299] a selecting module for selecting at least one RS resource based on the received indications;

[0300] a transmission module for transmitting an indication of the selected at least one RS resource to the UE; and

[0301] a physical channel receiving module for receiving a physical channel transmitted by the UE on an antenna of the UE associated with the indicated at least one RS resource.

Claims

1. A method (900) in a user equipment (UE) (50) for transmitting on different antenna subsets in the UE (50), the method (900) comprising: Sending (902) an indication that the UE (50) is capable of sending a plurality of different sounding reference signal (SRS) resources, wherein each SRS resource comprises at least one SRS port; Transmitting capability information, the capability information indicating that the UE (50) is capable of transmitting simultaneously on a plurality of SRS resources; receiving an SRS configuration of a plurality of SRS resource lists, wherein each SRS resource list includes a group of SRS resources that the UE cannot transmit simultaneously; simultaneously sending SRS resources selected from different lists of the plurality of SRS resource lists; receiving (906) an indication of at least one SRS resource; and A physical channel is transmitted (908) on an antenna of the UE associated with the indicated at least one SRS resource.

2. The method (900) according to claim 1, wherein The capability information indicates on which SRS resources the UE (50) can transmit simultaneously.

3. The method (900) according to claim 1 or 2, wherein: The method (900) further comprises: sending non-coherent MIMO transmissions using a multiple-input multiple-output MIMO layer on different antenna subsets in the UE (50), wherein: The method (900) further comprises sending an indication that the UE (50) is unable to control relative phases between antenna ports when transmitting on antenna ports corresponding to different SRS resources; The step of receiving (906) an indication of at least one SRS resource further comprises: receiving an indication of a plurality of SRS resources; and The step of transmitting (908) the physical channel includes transmitting a non-coherent MIMO transmission utilizing a different MIMO layer associated with each indicated SRS resource.

4. The method (900) according to claim 1 or 2, further comprising: receiving an indication of at least one precoder corresponding to each of the at least one SRS resource; as well as The physical channel is transmitted on an antenna of the UE (50) associated with the indicated at least one SRS resource using the indicated precoder.

5. The method (900) according to claim 1 or 2, further comprising: Adjusting the transmit power of the PUSCH corresponding to one or more SRS resource indicators, or adjusting the transmit power of one or more SRS resources corresponding to each SRS resource indicator, or adjusting both, wherein the transmit power corresponding to each of the one or more SRS resource indicators or each of the individual SRS resource indicators is adjusted by a power control command, and the power control command is different from the power control command for adjusting the transmit power corresponding to other SRS resource indicators in the one or more SRS resource indicators or the individual SRS resource indicators.

6. The method (900) according to claim 5, wherein A parameter set is associated with each SRS resource indicator, the method comprising determining transmit power using the parameter set, and wherein each parameter set is different from parameter sets associated with other SRS resource indicators.

7. The method (900) according to claim 1 or 2, wherein: Indicating a plurality of SRS resources to the UE (50), the method (900) further comprising: transmitting the physical channel on a plurality of antenna subsets corresponding to the indicated plurality of SRS resources using a precoder, the precoder jointly adjusting the phases of all SRS ports included in the indicated plurality of SRS resources.

8. A method (1100) of receiving, in a network node (30) of a wireless network, transmissions from a user equipment (UE) (50) performed on different antenna subsets in the UE (50), the method (1100) comprising: Receiving an indication that the UE (50) is capable of transmitting a plurality of different sounding reference signal (SRS) resources, wherein each SRS resource comprises at least one SRS port; receiving capability information indicating that the UE (50) is capable of transmitting simultaneously on a plurality of SRS resources; Sending an SRS configuration of multiple SRS resource lists, wherein each SRS resource list includes a group of SRS resources that the UE cannot transmit simultaneously; concurrently receiving SRS resources selected from different lists of the plurality of SRS resource lists; sending an SRS transmission request to the UE (50), the SRS transmission request being constructed by the network node (30) to avoid instructing the UE (50) to transmit SRS resources that the UE (50) cannot transmit simultaneously; selecting at least one SRS resource based on the received indication; sending an indication of the selected at least one SRS resource to the UE (50); and A physical channel transmitted by the UE (50) on an antenna of the UE (50) associated with the indicated at least one SRS resource is received.

9. The method (1100) according to claim 8, wherein The capability information indicates on which SRS resources the UE (50) can transmit simultaneously.

10. The method (1100) according to claim 8 or 9, wherein The method (1100) further comprises receiving non-coherent MIMO transmissions using MIMO layers sent on different antenna subsets in the UE (50), wherein: The method (1100) further includes receiving an indication that the UE (50) is unable to control relative phases between antenna ports when transmitting on antenna ports corresponding to different SRS resources; The step of sending an indication of at least one SRS resource includes sending a plurality of SRS resources; and The received physical channel is received using a different layer associated with each indicated SRS resource.

11. The method (1100) according to claim 8 or 9, further comprising: sending an indication of at least one precoder corresponding to each of the at least one SRS resource; as well as A physical channel transmitted using the indicated precoder is received.

12. The method (1100) according to claim 8 or 9, further comprising: A power control command corresponding to each of a plurality of SRS resource indicators for the UE (50) is sent to the UE (50) so as to adjust a transmit power corresponding to each SRS resource indicator with a power control command that is different from power control commands that adjust transmit power corresponding to other SRS resource indicators.

13. The method (1100) according to claim 8 or 9, wherein Indicating a plurality of SRS resources to the UE (50), the method (1100) further comprising: receiving a physical channel transmitted on a plurality of antenna subsets corresponding to the indicated plurality of SRS resources using a precoder, the precoder jointly adjusting the phase of all SRS ports included in the indicated plurality of SRS resources.

14. A user equipment (UE) (50) adapted to transmit on different antenna subsets in the UE (50), the UE (50) being adapted to: Sending an indication that the UE (50) is capable of sending a plurality of different sounding reference signal (SRS) resources, wherein: Each SRS resource includes at least one SRS port; Transmitting capability information, the capability information indicating that the UE (50) is capable of transmitting simultaneously on a plurality of SRS resources; receiving an SRS configuration of a plurality of SRS resource lists, wherein each SRS resource list includes a group of SRS resources that the UE cannot transmit simultaneously; simultaneously sending SRS resources selected from different lists of the plurality of SRS resource lists; receiving an indication of at least one SRS resource; and A physical channel is transmitted on an antenna of the UE (50) associated with the indicated at least one SRS resource.

15. The UE (50) according to claim 14, wherein The capability information indicates on which SRS resources the UE (50) can transmit simultaneously.

16. The UE (50) according to claim 14 or 15, wherein: The UE (50) is further adapted to send non-coherent MIMO transmissions using MIMO layers on different antenna subsets in the UE (50), wherein the UE (50) is adapted to: providing an indication that the UE (50) is unable to control relative phases between antenna ports corresponding to different SRS resources when transmitting on the antenna ports; receiving a plurality of SRS resources; and A non-coherent MIMO transmission utilizing a different MIMO layer associated with each indicated SRS resource is sent.

17. The UE (50) according to claim 14 or 15, wherein: The UE (50) is further adapted to: receiving an indication of at least one precoder corresponding to each of the at least one SRS resource; and The physical channel is transmitted on an antenna of the UE (50) associated with the indicated at least one SRS resource using the indicated precoder.

18. The UE (50) according to claim 14 or 15, wherein The UE (50) is further adapted to adjust the transmit power of a PUSCH corresponding to one or more SRS resource indicators, or to adjust the transmit power of one or more SRS resources corresponding to respective SRS resource indicators, or both, wherein the transmit power corresponding to each of the one or more SRS resource indicators or each of the respective SRS resource indicators is adjusted by a power control command that is different from a power control command that adjusts the transmit power corresponding to other SRS resource indicators of the one or more SRS resource indicators or the respective SRS resource indicators.

19. The UE (50) according to claim 18, wherein A parameter set is associated with each SRS resource indicator, wherein the UE (50) is further adapted to use the parameter set to determine transmit power, and wherein each parameter set is different from parameter sets associated with other SRS resource indicators.

20. The UE (50) according to claim 14 or 15, wherein A plurality of SRS resources are indicated to the UE (50), the UE (50) being further adapted to transmit the physical channel on a plurality of antenna subsets corresponding to the indicated plurality of SRS resources using a precoder, the precoder jointly adjusting the phases of all SRS ports included in the indicated plurality of SRS resources.

21. A network node (30) of a wireless network, adapted to receive transmissions from a user equipment (UE) (50) on different antenna subsets in the UE (50), wherein: The network node (30) is adapted to: Receiving an indication that the UE (50) is capable of transmitting a plurality of different sounding reference signal (SRS) resources, wherein each SRS resource comprises at least one SRS port; receiving capability information indicating that the UE (50) is capable of transmitting simultaneously on a plurality of SRS resources; Sending an SRS configuration of multiple SRS resource lists, wherein each SRS resource list includes a group of SRS resources that the UE cannot transmit simultaneously; concurrently receiving SRS resources selected from different lists of the plurality of SRS resource lists; sending an SRS transmission request to the UE (50), the SRS transmission request being constructed by the network node (30) to avoid instructing the UE (50) to transmit SRS resources that the UE (50) cannot transmit simultaneously; selecting at least one SRS resource based on the received indication; sending an indication of the selected at least one SRS resource to the UE (50); and A physical channel transmitted by the UE (50) on an antenna of the UE (50) associated with the indicated at least one SRS resource is received.

22. The network node (30) according to claim 21, wherein The capability information indicates on which SRS resources the UE (50) can transmit simultaneously.

23. The network node (30) according to claim 21 or 22, wherein The network node (30) is adapted to receive non-coherent MIMO transmissions using MIMO layers sent on different antenna subsets in the UE (50), wherein the network node (30) is adapted to: receiving an indication that the UE (50) is unable to control relative phases between antenna ports corresponding to different SRS resources when transmitting on the antenna ports; and Sending a plurality of SRS resources to the UE (50); The received channel is received using a different layer associated with each indicated SRS resource.

24. The network node (30) according to claim 21 or 22, wherein The network node (30) is further adapted to: sending an indication of at least one precoder corresponding to each of the at least one SRS resource; A physical channel transmitted using the indicated precoder is received.

25. The network node (30) according to claim 21 or 22, wherein The network node (30) is further adapted to send a power control command corresponding to each of a plurality of SRS resource indicators for the UE (50) to the UE (50) so as to adjust a transmit power corresponding to each SRS resource indicator with a power control command that is different from power control commands that adjust transmit power corresponding to other SRS resource indicators.

26. The network node (30) according to claim 21 or 22, wherein A plurality of SRS resources are indicated to the UE (50), wherein the received physical channel is transmitted by the UE (50) on a plurality of antenna subsets corresponding to the indicated plurality of SRS resources using a precoder that jointly adjusts the phases of all SRS ports included in the indicated plurality of SRS resources.

27. A user equipment (UE) (50) adapted to transmit on different antenna subsets in the UE (50), the UE (50) comprising: transceiver circuit (56); processing circuitry (52) operatively coupled to the transceiver circuitry (56); as well as A memory (64) coupled to the processing circuit (52), the memory (64) storing instructions for execution by the processing circuit (52), whereby the processing circuit (52) is configured to control the transceiver circuit (56) to: Sending an indication that the UE (50) is capable of sending a plurality of different sounding reference signal (SRS) resources, wherein each SRS resource includes at least one SRS port; Transmitting capability information, the capability information indicating that the UE (50) is capable of transmitting simultaneously on a plurality of SRS resources; receiving an SRS configuration of a plurality of SRS resource lists, wherein each SRS resource list includes a group of SRS resources that the UE cannot transmit simultaneously; simultaneously sending SRS resources selected from different lists of the plurality of SRS resource lists; receiving an indication of at least one SRS resource; and A physical channel is transmitted on an antenna of the UE (50) associated with the indicated at least one SRS resource.

28. The UE (50) according to claim 27, wherein The capability information indicates on which SRS resources the UE (50) can transmit simultaneously.

29. The UE (50) according to claim 27 or 28, wherein The processing circuit (52) is configured to send non-coherent MIMO transmissions using MIMO layers on different antenna subsets in the UE (50), wherein the processing circuit (52) is configured to: sending an indication that the UE (50) is unable to control relative phases between antenna ports when transmitting on antenna ports corresponding to different SRS resources; receiving a plurality of SRS resources; and A non-coherent MIMO transmission utilizing a different MIMO layer associated with each indicated SRS resource is sent.

30. The UE (50) according to claim 27 or 28, wherein The processing circuit (52) is configured to: receiving an indication of at least one precoder corresponding to each of the at least one SRS resource; and The physical channel is transmitted on an antenna of the UE (50) associated with the indicated at least one SRS resource using the indicated precoder.

31. The UE (50) according to claim 27 or 28, wherein The processing circuit (52) is configured to adjust the transmit power of the PUSCH corresponding to one or more SRS resource indicators, or to adjust the transmit power of one or more SRS resources corresponding to each SRS resource indicator, or to adjust both, wherein the transmit power corresponding to each of the one or more SRS resource indicators or each of the individual SRS resource indicators is adjusted by a power control command that is different from a power control command that adjusts the transmit power corresponding to other SRS resource indicators in the one or more SRS resource indicators or the individual SRS resource indicators.

32. The UE (50) according to claim 31, wherein A parameter set is associated with each SRS resource indicator, wherein the processing circuit is further configured to use the parameter set to determine transmit power, and wherein each parameter set is different from parameter sets associated with other SRS resource indicators.

33. The UE (50) according to claim 27 or 28, wherein A plurality of SRS resources are indicated to the UE (50), the processing circuit (52) being further configured to transmit the physical channel on a plurality of antenna subsets corresponding to the indicated plurality of SRS resources using a precoder, the precoder jointly adjusting the phases of all SRS ports included in the indicated plurality of SRS resources.

34. A network node (30) of a wireless network, adapted to receive transmissions from a user equipment (UE) (50) on different antenna subsets in the UE (50), the network node (30) comprising: transceiver circuit (36); processing circuitry (32) operatively coupled to the transceiver circuitry (36); as well as A memory (44) coupled to the processing circuit (32), the memory (44) storing instructions for execution by the processing circuit (32), whereby the processing circuit (32) is configured to control the transceiver circuit (36): Receiving an indication that the UE (50) is capable of transmitting a plurality of different reference signal SRS resources, wherein each SRS resource includes at least one SRS port; receiving capability information indicating that the UE (50) is capable of transmitting simultaneously on a plurality of SRS resources; Sending an SRS configuration of multiple SRS resource lists, wherein each SRS resource list includes a group of SRS resources that the UE cannot transmit simultaneously; concurrently receiving SRS resources selected from different lists of the plurality of SRS resource lists; sending an SRS transmission request to the UE (50), the SRS transmission request being constructed by the network node (30) to avoid instructing the UE (50) to transmit SRS resources that the UE (50) cannot transmit simultaneously; selecting at least one SRS resource based on the received indication; sending an indication of the selected at least one SRS resource to the UE (50); and A physical channel transmitted by the UE (50) on an antenna of the UE (50) associated with the indicated at least one SRS resource is received.

35. The network node (30) according to claim 34, wherein The capability information indicates on which SRS resources the UE (50) can transmit simultaneously.

36. The network node (30) according to claim 34 or 35, wherein The processing circuit (32) is configured to receive non-coherent MIMO transmissions using MIMO layers sent on different antenna subsets in the UE (50), wherein the processing circuit (32) is configured to: receiving an indication that the UE (50) is unable to control relative phases between antenna ports corresponding to different SRS resources when transmitting on the antenna ports; and Sending a plurality of SRS resources to the UE (50); The received channel is received using a different layer associated with each indicated SRS resource.

37. The network node (30) according to claim 34 or 35, wherein The processing circuit (32) is configured to: sending an indication of at least one precoder corresponding to each of the at least one SRS resource; and A physical channel transmitted using the indicated precoder is received.

38. The network node (30) according to claim 34 or 35, wherein The processing circuit (32) is configured to send a power control command corresponding to each of a plurality of SRS resource indicators for the UE (50) to the UE (50) so as to adjust a transmit power corresponding to each SRS resource indicator with a power control command that is different from power control commands that adjust transmit power corresponding to other SRS resource indicators.

39. The network node (30) according to claim 34 or 35, wherein A plurality of SRS resources are indicated to the UE (50), wherein the received physical channel is transmitted by the UE (50) on a plurality of antenna subsets corresponding to the indicated plurality of SRS resources using a precoder that jointly adjusts the phases of all SRS ports included in the indicated plurality of SRS resources.

40. A computer-readable storage medium comprising program instructions for a processing circuit (52) in a user equipment (UE) (50), wherein: The program instructions are configured to cause the UE (50) to perform the method (900) according to any one of claims 1-7 when the program instructions are executed by the processing circuit (52).

41. A computer-readable storage medium comprising program instructions for a processing circuit (32) in a network node (30), wherein: The program instructions are configured to cause the network node (30) to perform the method (1100) according to any one of claims 8-13 when the program instructions are executed by the processing circuit (32).

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