CYCLIC SHIFTING FOR SOUNDING REFERENCE SIGNAL PORTS

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive a configuration that indicates one or more cyclic shift parameters or one or more comb offset parameters per sounding reference signal (SRS) port. The UE may transmit one or more SRSs based at least in part on the one or more cyclic shift parameters per SRS port. Numerous other aspects are described.

FIELD OF THE DISCLOSURE

Aspects of the present disclosure generally relate to wireless communication and to techniques and apparatuses for cyclic shifting for sounding reference signal ports.

BACKGROUND

SUMMARY

Some aspects described herein relate to a method of wireless communication performed by a user equipment (UE). The method may include receiving a configuration that indicates one or more cyclic shift parameters or one or more comb offset parameters per sounding reference signal (SRS) port. The method may include transmitting one or more SRSs based at least in part on the one or more cyclic shift parameters or the one or more comb offset parameters per SRS port.

Some aspects described herein relate to a method of wireless communication performed by a network entity. The method may include transmitting a configuration that indicates one or more cyclic shift parameters or one or more comb offset parameters per SRS port. The method may include receiving one or more SRSs based at least in part on the one or more cyclic shift parameters or the one or more comb offset parameters per SRS port.

Some aspects described herein relate to a method of wireless communication performed by a UE. The method may include receiving a configuration for enabling or disabling cyclic shift hopping per SRS resource or per SRS resource set. The method may include performing cyclic shift hopping for SRSs based at least in part on the configuration.

Some aspects described herein relate to a method of wireless communication performed by a network entity. The method may include transmitting a configuration for enabling or disabling cyclic shift hopping per SRS resource or per SRS resource set. The method may include receiving SRSs according to cyclic shift hopping that is based at least in part on the configuration.

Some aspects described herein relate to a UE for wireless communication. The UE may include a memory and one or more processors coupled to the memory. The one or more processors may be configured to receive a configuration that indicates one or more cyclic shift parameters or one or more comb offset parameters per SRS port. The one or more processors may be configured to transmit one or more SRSs based at least in part on the one or more cyclic shift parameters or the one or more comb offset parameters per SRS port.

Some aspects described herein relate to a network entity for wireless communication. The network entity may include a memory and one or more processors coupled to the memory. The one or more processors may be configured to transmit a configuration that indicates one or more cyclic shift parameters or one or more comb offset parameters per SRS port. The one or more processors may be configured to receive one or more SRSs based at least in part on the one or more cyclic shift parameters or the one or more comb offset parameters per SRS port.

Some aspects described herein relate to a UE for wireless communication. The UE may include a memory and one or more processors coupled to the memory. The one or more processors may be configured to receive a configuration for enabling or disabling cyclic shift hopping per SRS resource or per SRS resource set. The one or more processors may be configured to perform cyclic shift hopping for SRSs based at least in part on the configuration.

Some aspects described herein relate to a network entity for wireless communication. The network entity may include a memory and one or more processors coupled to the memory. The one or more processors may be configured to transmit a configuration for enabling or disabling cyclic shift hopping per SRS resource or per SRS resource set. The one or more processors may be configured to receive SRSs according to cyclic shift hopping that is based at least in part on the configuration.

Some aspects described herein relate to a non-transitory computer-readable medium that stores a set of instructions for wireless communication by a UE. The set of instructions, when executed by one or more processors of the UE, may cause the UE to receive a configuration that indicates one or more cyclic shift parameters or one or more comb offset parameters per SRS port. The set of instructions, when executed by one or more processors of the UE, may cause the UE to transmit one or more SRSs based at least in part on the one or more cyclic shift parameters or the one or more comb offset parameters per SRS port.

Some aspects described herein relate to a non-transitory computer-readable medium that stores a set of instructions for wireless communication by a network entity. The set of instructions, when executed by one or more processors of the network entity, may cause the network entity to transmit a configuration that indicates one or more cyclic shift parameters or one or more comb offset parameters per SRS port. The set of instructions, when executed by one or more processors of the network entity, may cause the network entity to receive one or more SRSs based at least in part on the one or more cyclic shift parameters or the one or more comb offset parameters per SRS port.

Some aspects described herein relate to a non-transitory computer-readable medium that stores a set of instructions for wireless communication by a UE. The set of instructions, when executed by one or more processors of the UE, may cause the UE to receive a configuration for enabling or disabling cyclic shift hopping per SRS resource or per SRS resource set. The set of instructions, when executed by one or more processors of the UE, may cause the UE to perform cyclic shift hopping for SRSs based at least in part on the configuration.

Some aspects described herein relate to a non-transitory computer-readable medium that stores a set of instructions for wireless communication by a network entity. The set of instructions, when executed by one or more processors of the network entity, may cause the network entity to transmit a configuration for enabling or disabling cyclic shift hopping per SRS resource or per SRS resource set. The set of instructions, when executed by one or more processors of the network entity, may cause the network entity to receive SRSs according to cyclic shift hopping that is based at least in part on the configuration.

Some aspects described herein relate to an apparatus for wireless communication. The apparatus may include means for receiving a configuration that indicates one or more cyclic shift parameters or one or more comb offset parameters per SRS port. The apparatus may include means for transmitting one or more SRSs based at least in part on the one or more cyclic shift parameters or the one or more comb offset parameters per SRS port.

Some aspects described herein relate to an apparatus for wireless communication. The apparatus may include means for transmitting a configuration that indicates one or more cyclic shift parameters or one or more comb offset parameters per SRS port. The apparatus may include means for receiving one or more SRSs based at least in part on the one or more cyclic shift parameters or the one or more comb offset parameters per SRS port.

Some aspects described herein relate to an apparatus for wireless communication. The apparatus may include means for receiving a configuration for enabling or disabling cyclic shift hopping per SRS resource or per SRS resource set. The apparatus may include means for performing cyclic shift hopping for SRSs based at least in part on the configuration.

Some aspects described herein relate to an apparatus for wireless communication. The apparatus may include means for transmitting a configuration for enabling or disabling cyclic shift hopping per SRS resource or per SRS resource set. The apparatus may include means for receiving SRSs according to cyclic shift hopping that is based at least in part on the configuration.

Aspects generally include a method, apparatus, system, computer program product, non-transitory computer-readable medium, UE, base station, network entity, wireless communication device, and/or processing system as substantially described herein with reference to and as illustrated by the drawings and specification.

DETAILED DESCRIPTION

FIG.1is a diagram illustrating an example of a wireless network100, in accordance with the present disclosure. The wireless network100may be or may include elements of a 5G (e.g., NR) network and/or a 4G (e.g., Long Term Evolution (LTE)) network, among other examples. The wireless network100may include a user equipment (UE)120or multiple UEs120(shown as a UE120a, a UE120b, a UE120c, a UE120d, and a UE120e). The wireless network100may also include one or more network entities, such as base stations110(shown as a BS110a, a BS110b, a BS110c, and a BS110d), and/or other network entities. A base station110is a network entity that communicates with UEs120. A base station110(sometimes referred to as a BS) may include, for example, an NR base station, an LTE base station, a Node B, an eNB (e.g., in 4G), a gNB (e.g., in 5G), an access point, and/or a transmission reception point (TRP). Each base station110may provide communication coverage for a particular geographic area. In the Third Generation Partnership Project (3GPP), the term “cell” can refer to a coverage area of a base station110and/or a base station subsystem serving this coverage area, depending on the context in which the term is used.

The wireless network100may include one or more relay stations. A relay station is a network entity that can receive a transmission of data from an upstream station (e.g., a network entity or a UE120) and send a transmission of the data to a downstream station (e.g., a UE120or a network entity). A relay station may be a UE120that can relay transmissions for other UEs120. In the example shown inFIG.1, the BS110d(e.g., a relay base station) may communicate with the BS110a(e.g., a macro base station) and the UE120din order to facilitate communication between the BS110aand the UE120d. A base station110that relays communications may be referred to as a relay station, a relay base station, a relay, or the like.

A network controller130may couple to or communicate with a set network entities and may provide coordination and control for these network entities. The network controller130may communicate with the base stations110via a backhaul communication link. The network entities may communicate with one another directly or indirectly via a wireless or wireline backhaul communication link.

The frequencies between FR1 and FR2 are often referred to as mid-band frequencies. Recent 5G NR studies have identified an operating band for these mid-band frequencies as frequency range designation FR3 (7.125 GHz – 24.25 GHz). Frequency bands falling within FR3 may inherit FR1 characteristics and/or FR2 characteristics, and thus may effectively extend features of FR1 and/or FR2 into mid-band frequencies. In addition, higher frequency bands are currently being explored to extend 5G NR operation beyond 52.6 GHz. For example, three higher operating bands have been identified as frequency range designations FR4a or FR4-1 (52.6 GHz - 71 GHz), FR4 (52.6 GHz – 114.25 GHz), and FR5 (114.25 GHz – 300 GHz). Each of these higher frequency bands falls within the EHF band.

In some aspects, the UE120may include a communication manager140. As described in more detail elsewhere herein, the communication manager140may receive a configuration that indicates one or more cyclic shift parameters or one or more comb offset parameters per sounding reference signal (SRS) port. The communication manager140may transmit one or more SRSs based at least in part on the one or more cyclic shift parameters or the one or more comb offset parameters per SRS port.

In some aspects, the communication manager140may receive a configuration for enabling or disabling cyclic shift hopping per SRS resource or per SRS resource set. The communication manager140may perform cyclic shift hopping for SRSs based at least in part on the configuration. Additionally, or alternatively, the communication manager140may perform one or more other operations described herein.

In some aspects, the network entity may include a communication manager150. As described in more detail elsewhere herein, the communication manager150may transmit a configuration that indicates one or more cyclic shift parameters or one or more comb offset parameters per SRS port. The communication manager150may receive one or more SRSs based at least in part on the one or more cyclic shift parameters or the one or more comb offset parameters per SRS port.

In some aspects, the communication manager150may transmit a configuration for enabling or disabling cyclic shift hopping per SRS resource or per SRS resource set. The communication manager150may receive SRSs according to cyclic shift hopping that is based at least in part on the configuration. Additionally, or alternatively, the communication manager150may perform one or more other operations described herein.

The network controller130may include a communication unit294, a controller/processor290, and a memory292. The network controller130may include, for example, one or more devices in a core network. The network controller130may communicate with the network entity via the communication unit294.

A controller/processor of a network entity, (e.g., the controller/processor240of the base station110), the controller/processor280of the UE120, and/or any other component(s) ofFIG.2may perform one or more techniques associated with cyclic shift parameters and comb offset parameters per SRS port and/or cyclic shift hopping for SRS, as described in more detail elsewhere herein. For example, the controller/processor240of the base station110, the controller/processor280of the UE120, and/or any other component(s) ofFIG.2may perform or direct operations of, for example, process900ofFIG.9, process1000ofFIG.10, process1100ofFIG.11, process1200ofFIG.12, and/or other processes as described herein. The memory242and the memory282may store data and program codes for the network entity and the UE120, respectively. In some examples, the memory242and/or the memory282may include a non-transitory computer-readable medium storing one or more instructions (e.g., code and/or program code) for wireless communication. For example, the one or more instructions, when executed (e.g., directly, or after compiling, converting, and/or interpreting) by one or more processors of the network entity and/or the UE120, may cause the one or more processors, the UE120, and/or the network entity to perform or direct operations of, for example, process900ofFIG.9, process1000ofFIG.10, process1100ofFIG.11, process1200ofFIG.12, and/or other processes as described herein. In some examples, executing instructions may include running the instructions, converting the instructions, compiling the instructions, and/or interpreting the instructions, among other examples.

In some aspects, the UE120includes means for receiving a configuration that indicates one or more cyclic shift parameters or one or more comb offset parameters per SRS port; and/or means for transmitting one or more SRSs based at least in part on the one or more cyclic shift parameters or the one or more comb offset parameters per SRS port. The means for the UE120to perform operations described herein may include, for example, one or more of communication manager140, antenna252, modem254, MIMO detector256, receive processor258, transmit processor264, TX MIMO processor266, controller/processor280, or memory282.

In some aspects, the UE120includes means for receiving a configuration for enabling or disabling cyclic shift hopping per SRS resource or per SRS resource set; and/or means for performing cyclic shift hopping for SRSs based at least in part on the configuration.

In some aspects, the network entity includes means for transmitting a configuration that indicates one or more cyclic shift parameters or one or more comb offset parameters per SRS port; and/or means for receiving one or more SRSs based at least in part on the one or more cyclic shift parameters or the one or more comb offset parameters per SRS port. In some aspects, the means for the network entity to perform operations described herein may include, for example, one or more of communication manager150, transmit processor220, TX MIMO processor230, modem232, antenna234, MIMO detector236, receive processor238, controller/processor240, memory242, or scheduler246.

In some aspects, the network entity includes means for transmitting a configuration for enabling or disabling cyclic shift hopping per SRS resource or per SRS resource set; and/or means for receiving SRSs according to cyclic shift hopping that is based at least in part on the configuration.

FIG.3is a diagram illustrating an example of a disaggregated base station300, in accordance with the present disclosure.

The disaggregated base station300architecture may include one or more CUs310that can communicate directly with a core network320via a backhaul link, or indirectly with the core network320through one or more disaggregated base station units (such as a Near-RT RIC325via an E2 link, or a Non-RT RIC315associated with a Service Management and Orchestration (SMO) Framework305, or both). A CU310may communicate with one or more DUs330via respective midhaul links, such as an F1 interface. The DUs330may communicate with one or more RUs340via respective fronthaul links. The fronthaul link, the midhaul link, and the backhaul link may be generally referred to as “communication links.” The RUs340may communicate with respective UEs120via one or more RF access links. In some aspects, the UE120may be simultaneously served by multiple RUs340. The DUs330and the RUs340may also be referred to as “O-RAN DUs (O-DUs”) and “O-RAN RUs (O-RUs)”, respectively. A network entity may include a CU, a DU, an RU, or any combination of CUs, DUs, and RUs. A network entity may include a disaggregated base station or one or more components of the disaggregated base station, such as a CU, a DU, an RU, or any combination of CUs, DUs, and RUs. A network entity may also include one or more of a TRP, a relay station, a passive device, an intelligent reflective surface (IRS), or other components that may provide a network interface for or serve a UE, mobile station, sensor/actuator, or other wireless device.

Lower-layer functionality can be implemented by one or more RUs340. In some deployments, an RU340, controlled by a DU330, may correspond to a logical node that hosts RF processing functions, or low-PHY layer functions (such as performing fast Fourier transform (FFT), inverse FFT (iFFT), digital beamforming, physical random access channel (PRACH) extraction and filtering, or the like), or both, based at least in part on the functional split, such as a lower layer functional split. In such an architecture, the RU(s)340can be implemented to handle over the air (OTA) communication with one or more UEs120. In some implementations, real-time and non-real-time aspects of control and user plane communication with the RU(s)340can be controlled by the corresponding DU330. In some scenarios, this configuration can enable the DU(s)330and the CU310to be implemented in a cloud-based RAN architecture, such as a vRAN architecture.

FIG.4is a diagram illustrating an example400of SRS resource sets, in accordance with the present disclosure.

An uplink channel may include a physical uplink control channel (PUCCH) that carries uplink control information (UCI) or a physical uplink shared channel (PUSCH) that carries uplink data, among other examples. The uplink channel may also carry an uplink reference signal, such as a sounding reference signal (SRS). An SRS may carry information used for uplink channel estimation, which may be used for scheduling, link adaptation, precoder selection, or beam management, among other examples. The base station110may configure one or more SRS resource sets for the UE120, and the UE120may transmit SRSs on the configured SRS resource sets. An SRS resource set may have a configured usage, such as uplink channel state information (CSI) acquisition, downlink CSI acquisition for reciprocity-based operations, uplink beam management, among other examples. The base station110may measure the SRSs, may perform channel estimation based at least in part on the measurements, and may use the SRS measurements to configure communications with the UE120.

A base station110may configure a UE120with one or more SRS resource sets to allocate resources for SRS transmissions by the UE120. For example, a configuration for SRS resource sets may be indicated in a radio resource control (RRC) message (e.g., an RRC configuration message or an RRC reconfiguration message). As shown by reference number405, an SRS resource set may include one or more resources (e.g., shown as SRS resources), which may include time resources (e.g., a slot a symbols, a periodicity) and/or frequency resources (e.g., a resource block (RB)).

As shown by reference number410, an SRS resource may include one or more antenna ports on which an SRS is to be transmitted (e.g., in a time-frequency resource). Thus, a configuration for an SRS resource set may indicate one or more time-frequency resources in which an SRS is to be transmitted and may indicate one or more antenna ports on which the SRS is to be transmitted in those time-frequency resources. In some aspects, the configuration for an SRS resource set may indicate a use case (e.g., in an SRS-SetUse information element) for the SRS resource set. For example, an SRS resource set may have a use case of antenna switching, codebook, non-codebook, or beam management.

An antenna switching SRS resource set may be used to indicate downlink CSI with reciprocity between an uplink and downlink channel. For example, when there is reciprocity between an uplink channel and a downlink channel, a base station110may use an antenna switching SRS (e.g., an SRS transmitted using a resource of an antenna switching SRS resource set) to acquire downlink CSI (e.g., to determine a downlink precoder to be used to communicate with the UE120).

A codebook SRS resource set may be used to indicate uplink CSI when a base station110indicates an uplink precoder to the UE120. For example, when the base station110is configured to indicate an uplink precoder to the UE120(e.g., using a precoder codebook), the base station110may use a codebook SRS (e.g., an SRS transmitted using a resource of a codebook SRS resource set) to acquire uplink CSI (e.g., to determine an uplink precoder to be indicated to the UE120and used by the UE120to communicate with the base station110). In some aspects, virtual ports (e.g., a combination of two or more antenna ports) with a maximum transmit power may be supported at least for a codebook SRS.

A non-codebook SRS resource set may be used to indicate uplink CSI when the UE120selects an uplink precoder (e.g., instead of the base station110indicated an uplink precoder to be used by the UE120. For example, when the UE120is configured to select an uplink precoder, the base station110may use a non-codebook SRS (e.g., an SRS transmitted using a resource of a non-codebook SRS resource set) to acquire uplink CSI. In this case, the non-codebook SRS may be precoded using a precoder selected by the UE120(e.g., which may be indicated to the base station110).

A beam management SRS resource set may be used for indicating CSI for millimeter wave communications. An SRS resource can be configured as periodic, semi-persistent (sometimes referred to as semi-persistent scheduling (SPS)), or aperiodic. A periodic SRS resource may be configured via a configuration message that indicates a periodicity of the SRS resource (e.g., a slot-level periodicity, where the SRS resources occurs every Y slots) and a slot offset. In some cases, a periodic SRS resource may always be activated, and may not be dynamically activated or deactivated. A semi-persistent SRS resource may also be configured via a configuration message that indicates a periodicity and a slot offset for the semi-persistent SRS resource, and may be dynamically activated and deactivated (e.g., using downlink control information (DCI) or a medium access control (MAC) control element (CE) (MAC CE)). An aperiodic SRS resource may be triggered dynamically, such as via DCI (e.g., UE-specific DCI or group common DCI).

In some aspects, the UE120may be configured with a mapping between SRS ports (e.g., antenna ports) and corresponding SRS resources. The UE120may transmit an SRS on a particular SRS resource using an SRS port indicated in the configuration. In some aspects, an SRS resource may span N adjacent symbols within a slot (e.g., where N equals 1, 2, or 4). The UE120may be configured with X SRS ports (e.g., where X ≤ 4). In some aspects, each of the X SRS ports may mapped to a corresponding symbol of the SRS resource and used for transmission of an SRS in that symbol.

As shown inFIG.4, in some aspects, different SRS resource sets indicated to the UE120(e.g., having different use cases) may overlap (e.g., in time and/or in frequency, such as in the same slot). For example, as shown by reference number415, a first SRS resource set (e.g., shown as SRS Resource Set 1) is shown as having an antenna switching use case. As shown, this example antenna switching SRS resource set includes a first SRS resource (shown as SRS Resource A) and a second SRS resource (shown as SRS Resource B). Thus, antenna switching SRS may be transmitted in SRS Resource A (e.g., a first time-frequency resource) using antenna port 0 and antenna port 1 and may be transmitted in SRS Resource B (e.g., a second time-frequency resource) using antenna port 2 and antenna port 3.

As shown by reference number420, a second SRS resource set (e.g., shown as SRS Resource Set 2) may be a codebook use case. As shown, this example codebook SRS resource set includes only the first SRS resource (shown as SRS Resource A). Thus, codebook SRSs may be transmitted in SRS Resource A (e.g., the first time-frequency resource) using antenna port 0 and antenna port 1. In this case, the UE 120 may not transmit codebook SRSs in SRS Resource B (e.g., the second time-frequency resource) using antenna port 2 and antenna port 3.

FIG.5is a diagram illustrating an example500of a comb spacing and comb offsets slot format, in accordance with the present disclosure. Time-frequency resources in a radio access network may be partitioned into RBs, sometimes referred to as physical resource blocks (PRBs). Example500shows an RB505that may include a set of subcarriers (e.g., 12 subcarriers) and a set of symbols (e.g., 14 symbols) that are schedulable by a base station110as a unit. In some aspects, an RB505may include a set of subcarriers in a single slot. As shown, a single time-frequency resource included in an RB505may be referred to as a resource element (RE)510. An RE510may include a single subcarrier (e.g., in frequency) and a single symbol (e.g., in time). A symbol may be referred to as an OFDM symbol. An RE510may be used to transmit one modulated symbol, which may be a real value or a complex value.

In some telecommunication systems (e.g., NR), RBs505may span 12 subcarriers with a subcarrier spacing of, for example, 15 kilohertz (kHz), 30 kHz, 60 kHz, or 120 kHz, among other examples, over a 0.1 millisecond (ms) duration. A radio frame may include 40 slots and may have a length of 10 ms. Consequently, each slot may have a length of 0.25 ms. However, a slot length may vary depending on a numerology used to communicate (e.g., a subcarrier spacing and/or a cyclic prefix format). A slot may be configured with a link direction (e.g., downlink or uplink) for transmission. In some aspects, the link direction for a slot may be dynamically configured.

SRSs may be transmitted at different REs according to a comb pattern. A comb pattern may include a comb spacing, according to which SRSs may be spaced apart. Example500shows a comb spacing KTCthat can be configured as 2, 4, or 8 REs per SRS resource. SRS comb pattern512and SRS comb pattern514show a comb spacing of 2 REs in an OFDM symbol. SRS comb pattern516and SRS comb pattern518show a comb spacing of 4 REs in an OFDM symbol.

A comb pattern may also have a comb offset that indicates a shift of where the comb spacing starts (starting RE for an SRS). Example500shows a comb offsetkTCthat can be configured as 0, 1, ..., KTC— 1 per SRS resource. SRS comb pattern514has an offset of 1 and starts at subcarrier 1 rather than subcarrier 0. SRS comb pattern518has an offset of 2 and starts at subcarrier 2 rather than subcarrier 0.

A cyclic shift for an SRS delays a starting time reference for an SRS, which may be a different time reference than for another SRS. A UE may transmit an SRS with a cyclic shift

that can be configured as 0, 1, ...,

per SRS resource. The cyclic shift may start with the first SRS port if the SRS resource is configured withmore than one SRS port. The maximum quantity of cyclic shifts

depends on the comb spacing. For example, the maximum quantity of cyclic shifts

for a comb spacing of 2 may be 8, the maximum quantity of cyclic shifts

for a comb spacing of 4 may be 12, and the maximum quantity of cyclic shifts

for a comb spacing of 8 may be 6.

A transmission of an SRS with a cyclic shift for a base sequence may be represented as ejαinru,v(n), where aiis the cyclic shift for SRS transmission index i,ru,v(n) is the base sequence for n (quantity of RBs × quantity of REs / comb spacing KTC), u is a group identifier (ID), and v is a sequential value ID. Here j is the imaginary unit, which is used to represent a complex number, for example, a + bj, where a and b are real numbers. ejxis a complex exponential function (a different form to represent a complex number cos x + j sinx). The cyclic shift αimay be

where

is RRC-configured, Piis an antenna port number (starting from 1000), and

is the quantity of SRS ports.

Different cyclic shifts of the same base sequence are expected to be orthogonal, as long as the cyclic shift spacing does not become too small relative to the delay spread of the channel (difference between time of arrival of the earliest multi-path component and time of arrival of the latest multi-path component). Different cyclic shifts may be used for different SRS ports (in scenarios where an SRS resource has more than one SRS port) or for different SRS resources (either from the same UE or from different UEs). This may help ensure mutual orthogonality among all SRS ports of a given SRS resource, or among different SRS resources (of the same UE or of different UEs).

Even though different cyclic shifts (of the same base sequence) are theoretically orthogonal, in general, the larger the cyclic shift spacing between two SRS ports or SRS resources, the more resilient the SRS may be against a large delay spread and/or other implementation issues. Currently, for a given SRS resource with multiple ports, cyclic shifts are evenly distributed among the SRS ports, where the cyclic shift of the first port is RRC-configured for the SRS resource and represented as

For 2 ports, the assigned cyclic shifts may be (d0+ (0, 4))mod8 for a comb spacing of 2, (d0+ (0, 6))mod12 for a comb spacing of 4, and (d0+ (0, 3))mod6 for a comb spacing of 8. For 4 ports, the assigned cyclic shifts may be (d0+ (0, 2, 4, 6))mod8 for a comb spacing of 2, (d0+ (0, 3, 6, 9))mod12 for a comb spacing of 4, and (d0+ (0,3))mod6 for a comb spacing of 8 (ports (0, 2) and (1, 3) have the same cyclic shift but different comb offsets).

Given that only a subset of the maximum quantity of cyclic shifts is used for an SRS resource, other cyclic shifts may be used for other SRS resources (for the same UE or for different UEs). The maximum quantity of SRS resources that may be multiplexed on the same comb using different cyclic shifts of the same base sequence may be: for a comb spacing of 2, 8 for 1 antenna port, 4 for 2 antenna ports, or 2 for 4 antenna ports; for a comb spacing of 4, 12 for 1 antenna port, 6 for 2 antenna ports, or 3 for 4 antenna ports; and for a comb spacing of 8, 6 for 1 antenna port, 3 for 2 antenna ports, or 3 for 4 antenna ports (occupying two combs).

FIG.6is a diagram illustrating an example600of multiple TRPs that receive SRSs, in accordance with the present disclosure.

Example600shows clusters of 4 UEs that may each transmit an SRS to one of multiple TRPs. Coherent joint transmission (CJT) may involve beam-forming where the beam-forming antennas are not co-located but correspond to different TRPs. There may be SRS interference across the different UEs for CJT across the multiple TRPs, and any enhancements to address the SRS interference are expected to reuse existing SRS comb patterns. Example600shows that multiple TRPs may expect to receive an SRS from a given UE. For a large number of UEs, multiple UEs may need to send an SRS on the same OFDM symbols.

To account for SRS interference, a network entity may carefully assign comb offsets and cyclic shifts. However, it is not currently possible to configure a comb offset and a cyclic shift per SRS port in a given SRS resource. Rather, one comb offset and one comb cyclic shift are configured for an entire SRS resource. Cyclic shifts are evenly distributed among the SRS ports for the SRS resource. There is currently no flexibility to configure a comb offset or a cyclic shift for different SRS ports of an SRS resource. Furthermore, interference randomization may involve hopping across different cyclic shifts. However, cyclic shift hopping is not currently possible for SRS. Group/sequence hopping can only occur across different base sequences.

In other words, different SRS ports are transmitted on the same REs (same comb offset) with exceptions (for 4 ports) that are not very flexible. For example, for a comb spacing of 4 with 12 cyclic shifts involving a first UE with 2 SRS ports and a second UE with 2 SRS ports, the first UE may be assigned cyclic shifts {0, 6} and the second UE may be assigned cyclic shifts {2, 8}. However, it is not possible to assign cyclic shifts {0, 2} to the first UE and cyclic shifts {6, 8} to the second UE. In another example, for a comb spacing of 4 with 12 cyclic shifts involving a first UE with 4 SRS ports and a second UE with 2 SRS ports, the first UE may be assigned cyclic shifts {0, 3, 6, 9} and the second UE may be assigned cyclic shifts {2, 8}. However, it is not possible to assign cyclic shifts {0, 1, 2, 3} to the first UE and cyclic shifts {7, 8} to the second UE (to maximize the inter-UE cyclic shift separation). The lack of flexibility in assigning cyclic shifts and comb spacing to SRS ports may cause some SRS transmissions to be degraded and retransmitted due to SRS interference. This may consume additional processing resources and signaling resources.

FIG.7is a diagram illustrating an example700associated with configuring cyclic shift parameters and comb offsets values per SRS port, in accordance with the present disclosure. As shown inFIG.7, a network entity710(e.g., base station110) and a UE720(e.g., a UE120) may communicate with one another.

According to various aspects described herein, a network entity may configure a UE with cycle shift parameters and/or comb offset parameters per SRS port for a given SRS resource. That is, cyclic shift parameters and/or comb offset parameters may be specific to each individual SRS port, whether the parameters are configured for one SRS port, for each of some of the SRS ports of the UE, or for each of all of the SRS ports of the UE. By configuring cyclic shift parameters and/or comb offset parameters on a per-SRS-port basis (rather than per SRS resource), the UE may more accurately transmit SRSs to multiple TRPs and more successfully avoid SRS interference. By improving SRS transmissions and by better avoiding SRS interference, the network entity and the UE may conserve processing resources and signaling resources.

Example700shows an example per-SRS-port configuration. The UE720may have multiple SRS ports, such as SRS Ports 0-3. As shown by reference number725, the network entity710may transmit a configuration that indicates cyclic shift parameters and/or comb offset parameters per SRS port. In some aspects, the one or more cyclic shift parameters per SRS port may include antenna port cyclic shift values that correspond to multiple SRS ports. For example, the configuration may indicate Napcyclic shift values corresponding to each of NapSRS ports. For a first SRS port (e.g., Port 0), a shift spacing value d0may be

and Nap-1 additional shift spacing values may be used for the other SRS ports.

In some aspects, the configuration may indicate a cyclic shift spacing across consecutive ports. For example, with 4 ports and a cyclic shift spacing of 1, the configuration may indicate that the cyclic shift spacing is (d0+ {0,1,2,3})mod12 (for a comb spacing of 4). With a cyclic shift spacing 2, the cyclic shift spacing may be (d0+ {0,2,4,6})mod12. Furthermore, the configuration may indicate that the cyclic shift values associated with the cyclic spacing are sequential or evenly distributed. Sequential values may correspond to a cyclic shift spacing of 1.

In some aspects, the configuration may indicate one or more comb offset parameters per SRS port for an SRS resource with multiple SRS ports. That is, the configuration may indicate a comb offset value for each SRS port. This makes it possible for the network entity710to use different dimensions to ensure orthogonality for more flexibility. For example, the network entity710may assign the same cyclic shift (e.g., cyclic shift spacing 0) but with different comb offsets for multiple SRS ports. In some aspects, the configuration may explicitly indicate Napcomb offset values corresponding to NapSRS ports. The UE720may apply the existing comb offsetkTCto the first SRS port, and Nap-1 additional comb offsets may be used for the other SRS ports.

In some aspects, the configuration may indicate a comb offset spacing across consecutive SRS ports. For example, with 4 SRS ports and a comb offset spacing of 1, the comb offset may be (kTC+ {0,1,2,3})mod4 (for a comb spacing of 4). With a comb offset spacing of 0, the comb offset may be (kTC+ {0, 0,0,0})mod4. Instead of indicating the comb offset per SRS port, the configuration may indicate a comb offset per group of multiple SRS ports. For example, there may be one comb offset for SRS ports {1000, 1002} and another comb offset for SRS ports {1001, 1003}.

As shown by reference number730, the UE720may configure the SRS ports individually based at least in part on the configuration. As shown by reference number735, the UE720may transmit SRSs from the SRS ports using the per-SRS-port parameters.

FIG.8is a diagram illustrating an example800associated with configuring cyclic shift hopping for SRS, in accordance with the present disclosure. Example800shows the network entity710and the UE720.

Currently, group/sequence hopping may be across different base sequences r(u, v), and cyclic shift hopping is supported for PUCCH. The cyclic shift α may vary as a function of slot and symbol number. For example, the cyclic shift α may be represented by

where m0is an initial cyclic shift that is RRC configured per PUCCH resource,

is a quantity of cyclic shifts for PUCCH (e.g., 12),

is a slot number, l + l′ is a slot number within a slot, and

However, cyclic shift hopping is not currently possible for SRS.

According to various aspects described herein, the network entity710may configure UE720with cyclic shift hopping for SRS transmission. SRS transmission may benefit from cyclic shift hopping, especially for interference randomization. As shown by reference number825, the network entity710may transmit a configuration for enabling cyclic shift hopping per SRS resource or per SRS resource set. A configuration of a cyclic shift

may be used as an offset for the cyclic shift hopping. The cyclic shift in an lth OFDM symbol of an SRS resource for an ith SRS port may be represented as αi,lin an SRS transmission

For the first SRS port (i = 0), the UE720may determine the cyclic shift as a function of an OFDM symbol number (l0+ l) (cyclic shift determined per OFDM symbol), a slot number within a radio frame

the configured cyclic shift

(e.g., as an initial value/offset for the cyclic shift hopping), a maximum quantity of cyclic shifts

(which is a function of a comb spacing), and a pseudo-random sequence c(i) initialized by

(SRS sequence identity) at the beginning of each radio frame. For example,

The UE720may determine cyclic shifts for the remaining SRS antenna ports (in case the SRS resource is configured with more than one SRS port) based on the cyclic shift α0,1of the first SRS port and even/uniform distribution of cyclic shifts among the SRS ports. For example, for a second SRS port (e.g., the ith SRS port), the cyclic shift is

The UE720may then proceed with performing cyclic shift hopping for SRSs based at least in part on the configuration. As shown by reference number830, the UE720may perform a cyclic shift for a first SRS based at least in part on the configuration. As shown by reference number835, the UE720may transmit the first SRS on a first OFDM symbols. As shown by reference number840, the UE720may perform a cyclic shift with a hop for a second SRS on a second OFDM symbol based at least in part on the configuration. As shown by reference number845, the UE720may transmit the second SRS on the second OFDM symbol. By performing cyclic shift hopping for SRS transmissions, the network entity710and the UE720may better avoid SRS interference and conserve processing resources and signaling resources.

Alternatively, the network entity710may transmit a configuration that disables cyclic shift hopping for the SRS resource or the SRS resource set.

FIG.9is a diagram illustrating an example process900performed, for example, by a UE, in accordance with the present disclosure. Example process900is an example where the UE (e.g., a UE120, UE720) performs operations associated with cyclic shifting for SRS ports.

As shown inFIG.9, in some aspects, process900may include receiving a configuration that indicates one or more cyclic shift parameters or one or more comb offset parameters per SRS port (block910). For example, the UE (e.g., using communication manager1308and/or reception component1302depicted inFIG.13) may receive a configuration that indicates one or more cyclic shift parameters or one or more comb offset parameters per SRS port, as described above.

As further shown inFIG.9, in some aspects, process900may include transmitting one or more SRSs based at least in part on the one or more cyclic shift parameters or the one or more comb offset parameters per SRS port (block920). For example, the UE (e.g., using communication manager1308and/or transmission component1304depicted inFIG.13) may transmit one or more SRSs based at least in part on the one or more cyclic shift parameters or the one or more comb offset parameters per SRS port, as described above.

In a first aspect, the one or more cyclic shift parameters per SRS port include antenna port cyclic shift values corresponding to each of multiple SRS ports.

In a second aspect, alone or in combination with the first aspect, the configuration indicates a value for a cyclic shift spacing across consecutive SRS ports.

In a third aspect, alone or in combination with one or more of the first and second aspects, cycling shift values associated with the cyclic shift spacing are sequential.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, the one or more comb offset parameters per SRS port are for an SRS resource with multiple SRS ports.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, the configuration indicates a comb offset spacing across consecutive SRS ports.

FIG.10is a diagram illustrating an example process1000performed, for example, by a network entity, in accordance with the present disclosure. Example process1000is an example where the network entity (e.g., base station110, network entity710) performs operations associated with configuring cyclic shifting for SRS ports.

As shown inFIG.10, in some aspects, process1000may include transmitting a configuration that indicates one or more cyclic shift parameters or one or more comb offset parameters per SRS port (block1010). For example, the network entity (e.g., using communication manager1408and/or transmission component1404depicted inFIG.14) may transmit a configuration that indicates one or more cyclic shift parameters or one or more comb offset parameters per SRS port, as described above.

As further shown inFIG.10, in some aspects, process1000may include receiving one or more SRSs based at least in part on the one or more cyclic shift parameters or the one or more comb offset parameters per SRS port (block1020). For example, the network entity (e.g., using communication manager1408and/or reception component1402depicted inFIG.14) may receive one or more SRSs based at least in part on the one or more cyclic shift parameters or the one or more comb offset parameters per SRS port, as described above.

In a first aspect, the one or more cyclic shift parameters per SRS port include antenna port cyclic shift values corresponding to each of multiple SRS ports.

In a second aspect, alone or in combination with the first aspect, the configuration indicates a value for a cyclic shift spacing across consecutive SRS ports.

In a third aspect, alone or in combination with one or more of the first and second aspects, the cyclic shift spacing is sequential.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, the one or more comb offset parameters per SRS port are for an SRS resource with multiple SRS ports.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, the configuration indicates a comb offset spacing across consecutive SRS ports.

FIG.11is a diagram illustrating an example process1100performed, for example, by a UE, in accordance with the present disclosure. Example process1100is an example where the UE (e.g., a UE120, UE720) performs operations associated with cyclic shift hopping for SRS.

As shown inFIG.11, in some aspects, process1100may include receiving a configuration for enabling or disabling cyclic shift hopping per SRS resource or per SRS resource set (block1110). For example, the UE (e.g., using communication manager1308and/or reception component1302depicted inFIG.13) may receive a configuration for enabling or disabling cyclic shift hopping per SRS resource or per SRS resource set, as described above.

As further shown inFIG.11, in some aspects, process1100may include performing cyclic shift hopping for SRSs based at least in part on the configuration (block1120). For example, the UE (e.g., using communication manager1308and/or hopping component1310depicted inFIG.13) may perform cyclic shift hopping for SRSs based at least in part on the configuration, as described above.

In a first aspect, performing cyclic shift hopping includes using a cyclic shift configuration to apply an offset for the cyclic shift hopping.

In a second aspect, alone or in combination with the first aspect, process1100includes determining a cyclic shift for a first SRS port based at least in part on a symbol number, a slot number within a radio frame, the cyclic shift configuration, a maximum quantity of cyclic shifts as a function of comb spacing, and a pseudo-random sequence.

In a third aspect, alone or in combination with one or more of the first and second aspects, process1100includes determining a cyclic shift for a second SRS port based at least in part on the cyclic shift for the first SRS port and a distribution among SRS ports.

FIG.12is a diagram illustrating an example process1200performed, for example, by a network entity, in accordance with the present disclosure. Example process1200is an example where the network entity (e.g., base station110, network entity710) performs operations associated with configuring cyclic shift hopping for SRS.

As shown inFIG.12, in some aspects, process1200may include transmitting a configuration for enabling or disabling cyclic shift hopping per SRS resource or per SRS resource set (block1210). For example, the network entity (e.g., using communication manager1408and/or transmission component1404depicted inFIG.14) may transmit a configuration for enabling or disabling cyclic shift hopping per SRS resource or per SRS resource set, as described above.

As further shown inFIG.12, in some aspects, process1200may include receiving SRSs according to cyclic shift hopping that is based at least in part on the configuration (block1220). For example, the network entity (e.g., using communication manager1408and/or reception component1402depicted inFIG.14) may receive SRSs according to cyclic shift hopping that is based at least in part on the configuration, as described above.

In a first aspect, the cyclic shift hopping uses a cyclic shift configuration to apply an offset for the cyclic shift hopping.

In a second aspect, alone or in combination with the first aspect, process1200includes determining a cyclic shift for a first SRS port based at least in part on a symbol number, a slot number within a radio frame, the cyclic shift configuration, a maximum quantity of cyclic shifts as a function of comb spacing, and a pseudo-random sequence.

In a third aspect, alone or in combination with one or more of the first and second aspects, process1200includes determining a cyclic shift for a second SRS port based at least in part on the cyclic shift for the first SRS port and a distribution among SRS ports.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, receiving the SRSs includes receiving the SRSs according to the cyclic shift for the first SRS port and the cyclic shift for the second SRS port.

FIG.13is a diagram of an example apparatus1300for wireless communication. The apparatus1300may be a UE (e.g., a UE120, UE720), or a UE may include the apparatus1300. In some aspects, the apparatus1300includes a reception component1302and a transmission component1304, which may be in communication with one another (for example, via one or more buses and/or one or more other components). As shown, the apparatus1300may communicate with another apparatus1306(such as a UE, a base station, or another wireless communication device) using the reception component1302and the transmission component1304. As further shown, the apparatus1300may include the communication manager1308. The communication manager1308may control and/or otherwise manage one or more operations of the reception component1302and/or the transmission component1304. In some aspects, the communication manager1308may include one or more antennas, a modem, a controller/processor, a memory, or a combination thereof, of the UE described in connection withFIG.2. The communication manager1308may be, or be similar to, the communication manager150depicted inFIGS.1and2. For example, in some aspects, the communication manager1308may be configured to perform one or more of the functions described as being performed by the communication manager150. In some aspects, the communication manager1308may include the reception component1302and/or the transmission component1304. The communication manager1308may include a hopping component1310, among other examples.

In some aspects, the reception component1302may receive a configuration that indicates one or more cyclic shift parameters or one or more comb offset parameters per SRS port. The transmission component1304may transmit one or more SRSs based at least in part on the one or more cyclic shift parameters or the one or more comb offset parameters per SRS port.

In some aspects, the reception component1302may receive a configuration for enabling or disabling cyclic shift hopping per SRS resource or per SRS resource set.

The hopping component1310may perform cyclic shift hopping for SRSs based at least in part on the configuration. The hopping component1310may determine a cyclic shift for a first SRS port based at least in part on a symbol number, a slot number within a radio frame, the cyclic shift configuration, a maximum quantity of cyclic shifts as a function of comb spacing, and a pseudo-random sequence. The hopping component1310may determine a cyclic shift for a second SRS port based at least in part on the cyclic shift for the first SRS port and a distribution among SRS ports.

FIG.14is a diagram of an example apparatus1400for wireless communication. The apparatus1400may be a network entity (e.g., base station110, network entity710), or a network entity may include the apparatus1400. In some aspects, the apparatus1400includes a reception component1402and a transmission component1404, which may be in communication with one another (for example, via one or more buses and/or one or more other components). As shown, the apparatus1400may communicate with another apparatus1406(such as a UE, a base station, or another wireless communication device) using the reception component1402and the transmission component1404. As further shown, the apparatus1400may include the communication manager1408. The communication manager1408may control and/or otherwise manage one or more operations of the reception component1402and/or the transmission component1404. In some aspects, the communication manager1408may include one or more antennas, a modem, a controller/processor, a memory, or a combination thereof, of the network entity described in connection withFIG.2. The communication manager1408may be, or be similar to, the communication manager150depicted inFIGS.1and2. For example, in some aspects, the communication manager1408may be configured to perform one or more of the functions described as being performed by the communication manager150. In some aspects, the communication manager1408may include the reception component1402and/or the transmission component1404. The communication manager1408may include a hopping component1410, among other examples.

The transmission component1404may transmit a configuration that indicates one or more cyclic shift parameters or one or more comb offset parameters per SRS port. The reception component1402may receive one or more SRSs based at least in part on the one or more cyclic shift parameters or the one or more comb offset parameters per SRS port.

The transmission component1404may transmit a configuration for enabling or disabling cyclic shift hopping per SRS resource or per SRS resource set. The reception component1402may receive SRSs according to cyclic shift hopping that is based at least in part on the configuration.

The hopping component1410may determine a cyclic shift for a first SRS port based at least in part on a symbol number, a slot number within a radio frame, the cyclic shift configuration, a maximum quantity of cyclic shifts as a function of comb spacing, and a pseudo-random sequence. The hopping component1410may determine a cyclic shift for a second SRS port based at least in part on the cyclic shift for the first SRS port and a distribution among SRS ports.

The following provides an overview of some Aspects of the present disclosure:Aspect 1: A method of wireless communication performed by a user equipment (UE), comprising: receiving a configuration that indicates one or more cyclic shift parameters or one or more comb offset parameters per sounding reference signal (SRS) port; and transmitting one or more SRSs based at least in part on the one or more cyclic shift parameters or the one or more comb offset parameters per SRS port.Aspect 2: The method of Aspect 1, wherein the one or more cyclic shift parameters per SRS port include antenna port cyclic shift values corresponding to each of multiple SRS ports.Aspect 3: The method of Aspect 1 or 2, wherein the configuration indicates a value for a cyclic shift spacing across consecutive SRS ports.Aspect 4: The method of Aspect 3, wherein cycling shift values associated with the cyclic shift spacing are sequential.Aspect 5: The method of any of Aspects 1-4, wherein the one or more comb offset parameters per SRS port are for an SRS resource with multiple SRS ports.Aspect 6: The method of Aspect 5, wherein the configuration indicates a comb offset spacing across consecutive SRS ports.Aspect 7: A method of wireless communication performed by a network entity, comprising: transmitting a configuration that indicates one or more cyclic shift parameters or one or more comb offset parameters per sounding reference signal (SRS) port; and receiving one or more SRSs based at least in part on the one or more cyclic shift parameters or the one or more comb offset parameters per SRS port.Aspect 8: The method of Aspect 7, wherein the one or more cyclic shift parameters per SRS port include antenna port cyclic shift values corresponding to each of multiple SRS ports.Aspect 9: The method of Aspect 7 or 8, wherein the configuration indicates a value for a cyclic shift spacing across consecutive SRS ports.Aspect 10: The method of Aspect 9, wherein the cyclic shift spacing is sequential.Aspect 11: The method of any of Aspects 7-10, wherein the one or more comb offset parameters per SRS port are for an SRS resource with multiple SRS ports.Aspect 12: The method of Aspect 11, wherein the configuration indicates a comb offset spacing across consecutive SRS ports.Aspect 13: A method of wireless communication performed by a user equipment (UE), comprising: receiving a configuration for enabling or disabling cyclic shift hopping per sounding reference signal (SRS) resource or per SRS resource set; and performing cyclic shift hopping for SRSs based at least in part on the configuration.Aspect 14: The method of Aspect 13, wherein performing cyclic shift hopping includes using a cyclic shift configuration to apply an offset for the cyclic shift hopping.Aspect 15: The method of Aspect 14, further comprising determining a cyclic shift for a first SRS port based at least in part on a symbol number, a slot number within a radio frame, the cyclic shift configuration, a maximum quantity of cyclic shifts as a function of comb spacing, and a pseudo-random sequence.Aspect 16: The method of Aspect 15, further comprising determining a cyclic shift for a second SRS port based at least in part on the cyclic shift for the first SRS port and a distribution among SRS ports.Aspect 17: A method of wireless communication performed by a network entity, comprising: transmitting a configuration for enabling or disabling cyclic shift hopping per sounding reference signal (SRS) resource or per SRS resource set; and receiving SRSs according to cyclic shift hopping that is based at least in part on the configuration.Aspect 18: The method of Aspect 17, wherein the cyclic shift hopping uses a cyclic shift configuration to apply an offset for the cyclic shift hopping.Aspect 19: The method of Aspect 18, further comprising determining a cyclic shift for a first SRS port based at least in part on a symbol number, a slot number within a radio frame, the cyclic shift configuration, a maximum quantity of cyclic shifts as a function of comb spacing, and a pseudo-random sequence.Aspect 20: The method of Aspect 19, further comprising determining a cyclic shift for a second SRS port based at least in part on the cyclic shift for the first SRS port and a distribution among SRS ports.Aspect 21: The method of Aspect 20, wherein receiving the SRSs includes receiving the SRSs according to the cyclic shift for the first SRS port and the cyclic shift for the second SRS port.Aspect 22: An apparatus for wireless communication at a device, comprising a processor; memory coupled with the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform the method of one or more of Aspects 1-21.Aspect 23: A device for wireless communication, comprising a memory and one or more processors coupled to the memory, the one or more processors configured to perform the method of one or more of Aspects 1-21.Aspect 24: An apparatus for wireless communication, comprising at least one means for performing the method of one or more of Aspects 1-21.Aspect 25: A non-transitory computer-readable medium storing code for wireless communication, the code comprising instructions executable by a processor to perform the method of one or more of Aspects 1-21.Aspect 26: A non-transitory computer-readable medium storing a set of instructions for wireless communication, the set of instructions comprising one or more instructions that, when executed by one or more processors of a device, cause the device to perform the method of one or more of Aspects 1-21.