REDUCED COMPLEXITY PHYSICAL DOWNLINK CONTROL CHANNEL DECODING

Wireless communications systems and methods related to communicating control information are provided. A method of wireless communication performed by a user equipment (UE) may include monitoring a first set of physical downlink control channel (PDCCH) candidate resources for a PDCCH communication from a network unit, receiving, from the network unit, a plurality of demodulation reference signals (DMRSs), and decoding, based on a metric associated with the plurality of demodulation reference signals (DMRSs) satisfying a threshold, the PDCCH communication.

TECHNICAL FIELD

This application relates to wireless communication systems, and more particularly, to reduced complexity physical downlink control channel (PDCCH) decoding.

INTRODUCTION

NR may support various deployment scenarios to benefit from the various spectrums in different frequency ranges, licensed and/or unlicensed, and/or coexistence of the LTE and NR technologies. For example, NR can be deployed in a standalone NR mode over a licensed and/or an unlicensed band or in a dual connectivity mode with various combinations of NR and LTE over licensed and/or unlicensed bands.

In a wireless communication network, a BS may communicate with a UE in an uplink direction and a downlink direction. Sidelink was introduced in LTE to allow a UE to send data to another UE (e.g., from one vehicle to another vehicle) without tunneling through the BS and/or an associated core network. The LTE sidelink technology has been extended to provision for device-to-device (D2D) communications, vehicle-to-everything (V2X) communications, and/or cellular vehicle-to-everything (C-V2X) communications. Similarly, NR may be extended to support sidelink communications, D2D communications, V2X communications, and/or C-V2X over licensed frequency bands and/or unlicensed frequency bands (e.g., shared frequency bands).

BRIEF SUMMARY OF SOME EXAMPLES

In an aspect of the disclosure, a method of wireless communication performed by a user equipment (UE), may include monitoring a first set of physical downlink control channel (PDCCH) candidate resources for a PDCCH communication from a network unit, receiving, from the network unit, a plurality of demodulation reference signals (DMRSs), and decoding, based on a metric associated with the plurality of demodulation reference signals (DMRSs) satisfying a threshold, the PDCCH communication.

In an additional aspect of the disclosure, a method of wireless communication performed by a network unit may include transmitting an indication of a set of physical downlink control channel (PDCCH) candidate resources, transmitting a plurality of demodulation reference signals (DMRSs), and receiving, based on a metric associated with the plurality of DMRSs, a communication.

In an additional aspect of the disclosure, a user equipment (UE) may include a memory; a transceiver; and at least one processor coupled to the memory and the transceiver, wherein the UE is configured to monitor a first set of physical downlink control channel (PDCCH) candidate resources for a PDCCH communication from a network unit, receive, from the network unit, a plurality of demodulation reference signals (DMRSs), and decode, based on a metric associated with the plurality of demodulation reference signals (DMRSs) satisfying a threshold, the PDCCH communication.

In an additional aspect of the disclosure, an apparatus for wireless communications may include a processor; memory coupled with the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to transmit an indication of a set of physical downlink control channel (PDCCH) candidate resources, transmit a plurality of demodulation reference signals (DMRSs), and receive, based on a metric associated with the plurality of DMRSs, a communication.

Other aspects, features, and instances of the present invention will become apparent to those of ordinary skill in the art, upon reviewing the following description of specific, exemplary instances of the present invention in conjunction with the accompanying figures. While features of the present invention may be discussed relative to certain aspects and figures below, all instances of the present invention can include one or more of the advantageous features discussed herein. In other words, while one or more instances may be discussed as having certain advantageous features, one or more of such features may also be used in accordance with the various instances of the invention discussed herein. In similar fashion, while exemplary aspects may be discussed below as device, system, or method instances it should be understood that such exemplary instances can be implemented in various devices, systems, and methods.

DETAILED DESCRIPTION

The deployment of NR over an unlicensed spectrum is referred to as NR-unlicensed (NR-U). Federal Communications Commission (FCC) and European Telecommunications Standards Institute (ETSI) are working on regulating 6 GHz as a new unlicensed band for wireless communications. The addition of 6 GHz bands allows for hundreds of megahertz (MHz) of bandwidth (BW) available for unlicensed band communications. Additionally, NR-U can also be deployed over 2.4 GHz unlicensed bands, which are currently shared by various radio access technologies (RATs), such as IEEE 802.11 wireless local area network (WLAN) or WiFi and/or license assisted access (LAA). Sidelink communications may benefit from utilizing the additional bandwidth available in an unlicensed spectrum. However, channel access in a certain unlicensed spectrum may be regulated by authorities. For instance, some unlicensed bands may impose restrictions on the power spectral density (PSD) and/or minimum occupied channel bandwidth (OCB) for transmissions in the unlicensed bands. For example, the unlicensed national information infrastructure (UNII) radio band has a minimum OCB requirement of about 70 percent (%).

Some sidelink systems may operate over a 20 MHz bandwidth in an unlicensed band. A BS may configure a sidelink resource pool over the 20 MHz band for sidelink communications. A sidelink resource pool is typically partitioned into multiple frequency subchannels or frequency subbands (e.g., about 5 MHz each) and a sidelink UE may select a sidelink resource (e.g., a subchannel) from the sidelink resource pool for sidelink communication. To satisfy an OCB of about 70%, a sidelink resource pool may utilize a frequency-interlaced structure. For instance, a frequency-interlaced-based sidelink resource pools may include a plurality of frequency interlaces over the 20 MHz band, where each frequency interlace may include a plurality of resource blocks (RBs) distributed over the 20 MHz band. For example, the plurality of RBs of a frequency interlace may be spaced apart from each other by one or more other RBs in the 20 MHz unlicensed band. A sidelink UE may select a sidelink resource in the form of frequency interlaces from the sidelink resource pool for sidelink communication. In other words, sidelink transmissions may utilize a frequency-interlaced waveform to satisfy an OCB of the unlicensed band. However, S-SSBs may be transmitted in a set of contiguous RBs, for example, in about eleven contiguous RBs. As such, S-SSB transmissions alone may not meet the OCB requirement of the unlicensed band. Accordingly, it may be desirable for a sidelink sync UE to multiplex an S-SSB transmission with one or more channel state information reference signals (CSI-RSs) in a slot configured for S-SSB transmission so that the sidelink sync UE's transmission in the slot may comply with an OCB requirement.

The present application describes mechanisms for a sidelink UE to multiplex an S-SSB transmission with a CSI-RS transmission in a frequency band to satisfy an OCB of the frequency band. For instance, the sidelink UE may determine a multiplex configuration for multiplexing a CSI-RS transmission with an S-SSB transmission in a sidelink BWP. The sidelink UE may transmit the S-SSB transmission in the sidelink BWP during a sidelink slot. The sidelink UE may transmit one or more CSI-RSs in the sidelink BWP during the sidelink slot by multiplexing the CSI-RS and the S-SSB transmission based on the multiplex configuration.

In some aspects, the sidelink UE may transmit the S-SSB transmission at an offset from a lowest frequency of the sidelink BWP based on a synchronization raster (e.g., an NR-U sync raster). In some aspects, the sidelink UE may transmit the S-SSB transmission aligned to a lowest frequency of the sidelink BWP. For instance, a sync raster can be defined for sidelink such that the S-SSB transmission may be aligned to a lowest frequency of the sidelink BWP.

In some aspects, the multiplex configuration includes a configuration for multiplexing the S-SSB transmission with a frequency interlaced waveform sidelink transmission to meet the OCB requirement. For instance, the sidelink transmission may include a CSI-RS transmission multiplexed in frequency within a frequency interlace with RBs spaced apart in the sidelink BWP. In some instances, the sidelink UE may rate-match the CSI-RS transmission around RBs that are at least partially overlapping with the S-SSB transmission.

In some aspects, the multiplex configuration includes a configuration for multiplexing the S-SSB transmission with a subchannel-based sidelink transmission to meet the OCB requirement. For instance, the sidelink transmission may include a CSI-RS transmission multiplexed in time within a subchannel including contiguous RBs in the sidelink BWP. For instance, the S-SSB transmission may be transmitted at a low frequency portion of the sidelink BWP, and the CSI-RS may be transmitted in a subchannel located at a high frequency portion of the sidelink BWP to meet the OCB.

In some aspects, a BS may configure different sidelink resource pools for slots that are associated with S-SSB transmissions and for slots that are not associated with S-SSB transmissions. For instance, the BS may configure a first resource pool with a frequency-interlaced structure for slots that are not configured for S-SSB transmissions. The first resource pool may include a plurality of frequency interlaces (e.g., distributed RBs), where each frequency interlace may carry a PSCCH/PSSCH transmission. The BS may configure a second resource pool with a subchannel-based structure for slots that are configured for S-SSB transmission. The second resource pool may include a plurality of frequency subchannels (e.g., contiguous RBs), where each subchannel may carry a PSCCH/PSSCH transmission. To satisfy an OCB in a sidelink slot configured for an S-SSB transmission, the sidelink UE (e.g., a sidelink sync UE) may transmit an S-SSB transmission multiplexed with a CSI-RS transmission. For instance, the S-SSB transmission may be transmitted in frequency resources located at a lower frequency portion of a sidelink BWP and the CSI-RS transmission may be transmitted in frequency resources located at higher frequency portion of the sidelink BWP.

The BSs105may also communicate with a core network. The core network may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. At least some of the BSs105(e.g., which may be an example of an evolved NodeB (eNB) or an access node controller (ANC)) may interface with the core network130through backhaul links (e.g., S1, S2, etc.) and may perform radio configuration and scheduling for communication with the UEs115. In various examples, the BSs105may communicate, either directly or indirectly (e.g., through core network), with each other over backhaul links (e.g., X1, X2, etc.), which may be wired or wireless communication links.

In some instances, a UE115attempting to access the network100may perform an initial cell search by detecting a PSS from a BS105. The PSS may enable synchronization of period timing and may indicate a physical layer identity value. The UE115may then receive an SSS. The SSS may enable radio frame synchronization, and may provide a cell identity value, which may be combined with the physical layer identity value to identify the cell. The SSS may also enable detection of a duplexing mode and a cyclic prefix length. The PSS and the SSS may be located in a central portion of a carrier or any suitable frequencies within the carrier.

After receiving the PSS and SSS, the UE115may receive a MIB. The MIB may include system information for initial network access and scheduling information for RMSI and/or OSI. After decoding the MIB, the UE115may receive RMSI and/or OSI. The RMSI and/or OSI may include radio resource control (RRC) information related to random access channel (RACH) procedures, paging, control resource set (CORESET) for physical downlink control channel (PDCCH) monitoring, physical uplink control channel (PUCCH), physical uplink shared channel (PUSCH), power control, SRS, and cell barring.

After obtaining the MIB, the RMSI and/or the OSI, the UE115can perform a random access procedure to establish a connection with the BS105. For the random access procedure, the UE115may transmit a random access preamble and the BS105may respond with a random access response. Upon receiving the random access response, the UE115may transmit a connection request to the BS105and the BS105may respond with a connection response (e.g., contention resolution message).

After establishing a connection, the UE115and the BS105can enter a normal operation stage, where operational data may be exchanged. For example, the BS105may schedule the UE115for UL and/or DL communications. The BS105may transmit UL and/or DL scheduling grants to the UE115via a PDCCH. The BS105may transmit a DL communication signal to the UE115via a PDSCH according to a DL scheduling grant. The UE115may transmit a UL communication signal to the BS105via a PUSCH and/or PUCCH according to a UL scheduling grant.

The network100may be designed to enable a wide range of use cases. While in some examples a network100may utilize monolithic base stations, there are a number of other architectures which may be used to perform aspects of the present disclosure. For example, a BS105may be separated into a remote radio head (RRH) and baseband unit (BBU). BBUs may be centralized into a BBU pool and connected to RRHs through low-latency and high-bandwidth transport links, such as optical transport links. BBU pools may be cloud-based resources. In some aspects, baseband processing is performed on virtualized servers running in data centers rather than being co-located with a BS105. In another example, based station functionality may be split between a remote unit (RU), distributed unit (DU), and a central unit (CU). An RU generally performs low physical layer functions while a DU performs higher layer functions, which may include higher physical layer functions. A CU performs the higher RAN functions, such as radio resource control (RRC).

For simplicity of discussion, the present disclosure refers to methods of the present disclosure being performed by base stations, or more generally network entities, while the functionality may be performed by a variety of architectures other than a monolithic base station. In addition to disaggregated base stations, aspects of the present disclosure may also be performed by a centralized unit (CU), a distributed unit (DU), a radio unit (RU), a Near-Real Time (Near-RT) RAN Intelligent Controller (RIC), a Non-Real Time (Non-RT) RIC, integrated access and backhaul (IAB) node, a relay node, a sidelink node, etc.

In some aspects, a method of wireless communication may be performed by the UE115. The method may include monitoring a first set of physical downlink control channel (PDCCH) candidate resources for a PDCCH communication from the BS105, receiving, from the BS105, a plurality of demodulation reference signals (DMRSs) and decoding, based on a metric associated with the plurality of demodulation reference signals (DMRSs) satisfying a threshold, the PDCCH communication.

FIG.2shows a diagram illustrating an example disaggregated base station1200architecture. The disaggregated base station1200architecture may include one or more central units (CUs)1210that can communicate directly with a core network1220via a backhaul link, or indirectly with the core network1220through one or more disaggregated base station units (such as a Near-Real Time (Near-RT) RAN Intelligent Controller (RIC)1225via an E2 link, or a Non-Real Time (Non-RT) RIC1215associated with a Service Management and Orchestration (SMO) Framework1205, or both). A CU1210may communicate with one or more distributed units (DUs)1230via respective midhaul links, such as an F1 interface. The DUs1230may communicate with one or more radio units (RUs)1240via respective fronthaul links. The RUs1240may communicate with respective UEs120via one or more radio frequency (RF) access links. In some implementations, the UE120may be simultaneously served by multiple RUs1240.

Lower-layer functionality can be implemented by one or more RUs1240. In some deployments, an RU1240, controlled by a DU1230, 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)1240can 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)1240can be controlled by the corresponding DU1230. In some scenarios, this configuration can enable the DU(s)1230and the CU1210to be implemented in a cloud-based RAN architecture, such as a vRAN architecture.

The SMO Framework1205may be configured to support RAN deployment and provisioning of non-virtualized and virtualized network elements. For non-virtualized network elements, the SMO Framework1205may be configured to support the deployment of dedicated physical resources for RAN coverage requirements which may be managed via an operations and maintenance interface (such as an O1 interface). For virtualized network elements, the SMO Framework1205may be configured to interact with a cloud computing platform (such as an open cloud (O-Cloud)1290) to perform network element life cycle management (such as to instantiate virtualized network elements) via a cloud computing platform interface (such as an O2 interface). Such virtualized network elements can include, but are not limited to, CUs1210, DUs1230, RUs1240and Near-RT RICs1225. In some implementations, the SMO Framework1205can communicate with a hardware aspect of a 4G RAN, such as an open eNB (O-eNB)1211, via an O1 interface. Additionally, in some implementations, the SMO Framework1205can communicate directly with one or more RUs1240via an O1 interface. The SMO Framework1205also may include a Non-RT RIC1215configured to support functionality of the SMO Framework1205.

The Non-RT RIC1215may be configured to include a logical function that enables non-real-time control and optimization of RAN elements and resources, Artificial Intelligence/Machine Learning (AI/ML) workflows including model training and updates, or policy-based guidance of applications/features in the Near-RT RIC1225. The Non-RT RIC1215may be coupled to or communicate with (such as via an A1 interface) the Near-RT RIC1225. The Near-RT RIC1225may be configured to include a logical function that enables near-real-time control and optimization of RAN elements and resources via data collection and actions over an interface (such as via an E2 interface) connecting one or more CUs1210, one or more DUs1230, or both, as well as an O-eNB, with the Near-RT RIC1225.

In some implementations, to generate AI/ML models to be deployed in the Near-RT RIC1225, the Non-RT RIC1215may receive parameters or external enrichment information from external servers. Such information may be utilized by the Near-RT RIC1225and may be received at the SMO Framework1205or the Non-RT RIC1215from non-network data sources or from network functions. In some examples, the Non-RT RIC1215or the Near-RT RIC1225may be configured to tune RAN behavior or performance. For example, the Non-RT RIC1215may monitor long-term trends and patterns for performance and employ AI/ML models to perform corrective actions through the SMO Framework1205(such as reconfiguration via O1) or via creation of RAN management policies (such as A1 policies).

In some aspects, a method of wireless communication may be performed by the UE120. The method may include monitoring a first set of physical downlink control channel (PDCCH) candidate resources for a PDCCH communication from the RU1240, receiving, from the RU1240, a plurality of demodulation reference signals (DMRSs) and decoding, based on a metric associated with the plurality of demodulation reference signals (DMRSs) satisfying a threshold, the PDCCH communication.

FIG.3illustrates resources300associated with a PDCCH communication according to some aspects of the present disclosure. In some aspects a UE (e.g., the UE115,120, or600) may monitor a first set of physical downlink control channel (PDCCH) candidate resources328for a PDCCH communication from a network unit (e.g., the BS105, the CU1210, the DU1230, the RU1240, and/or network unit700). In this regard, the UE may monitor time/frequency resources for a PDCCH communication intended for the UE. The PDDCH communication may be intended for the UE based on an identifier (e.g., a radio network temporary identifier (RNTI)) associated with the UE. A network unit (e.g., the BS105, the CU1210, the DU1230, the RU1240, and/or network unit700) may configure the UE (e.g., configure via RRC signaling) with one or more control resource sets (CORESETs) in one or more frequency sub-bands (e.g., one or more frequency channels and/or sub-channels). A CORESET may include a set of frequency resources over a number of symbols (e.g., a number of symbols in time) indicated by a duration320. The network unit may configure the UE with one or more search spaces (e.g., time/frequency resources300in the downlink resource grid that may carry the PDCCH communication intended for the UE) for PDCCH328monitoring based on the one or more CORESETs. The duration320of the CORESET may include any suitable number (e.g., 1, 2, 3, 4, or more) of symbols. In the example ofFIG.3, the duration320may include 2 symbols. The UE may perform blind decoding in the search spaces to search for DCI information from the network unit. For example, the network unit may configure the UE with the frequency sub-bands, the CORESETs, and/or the PDCCH search spaces as control channel elements304and/or resource element groups310via RRC configurations. Accordingly, the UE may perform blind decoding in one or more search spaces that may be configured via RRC signaling. The network unit (e.g., the BS105, the CU1210, the DU1230, the RU1240, or the RU1240) may transmit a plurality of PDCCH communications (e.g., a first set of PDCCH communications) intended for multiple UEs in the time/frequency resources300associated with the one or more search spaces configured for the UE. The plurality of PDCCH communications328transmitted by the network unit may include the first PDCCH intended for the UE.

The number of PDCCH candidate resources328searched by the UE may be based on an aggregation level (AL). The AL may indicate the number of control channel elements (CCEs)304within a bandwidth part302used for each PDCCH candidate328. Each CCE304may include six resource elements groups (REGs)310(0) . . .310(5) or other suitable number of REGs310, where a REG310can be one physical RB in one symbol. The AL may be based on a quality of the channel. For example, if the UE is located near the network unit, the AL may be lower as compared to when the UE is farther from the network unit. The higher the AL, the more redundancy and more frequency diversity can be provided by the PDCCH transmission, and thus the more robust the PDCCH transmission may be.

The UE may attempt to blind decode a cyclic redundancy check (CRC) within the search spaces with an RNTI value (such as C-RNTI for UE-specific search spaces, or other RNTI types for common search spaces) using a trial-and-error approach of resource locations and parameters. This blind decoding method may consume finite resources associated with the UE. Such finite resources may be limited depending on per slot capabilities of the UE such as the number of PDCCH328blind decoding candidates per slot and/or the number of CCEs304that the UE may monitor per slot. Monitoring all of the PDCCH328candidate resources for the PDCCH328communication intended for the UE may consume more power and/or computing resources associated with the UE as compared to monitoring a subset of the PDCCH328candidate resources. In accordance with the present disclosure, the UE may select a subset of the PDCCH328candidate resources for monitoring in order to reduce power and/or computing resources associated with the UE.

In some aspects, a UE (e.g., the UE115,120, or600) may receive a plurality of demodulation reference signals (DMRSs)330from the network unit. In this regard, the plurality of DMRSs330may assist the UE in decoding information from the PDCCH328communication. The network unit may include the plurality of DMRSs330in the time/frequency resources300associated with the one or more search spaces to assist the UE in channel estimation and/or PDCCH328decoding.

In some aspects, upon receiving one or more candidate PDCCH328communications from the network unit in the one or more search spaces, the UE may estimate a channel response from the associated DMRSs330, perform demodulation of the candidate PDCCH328communications based on an estimated channel response, and/or decode data from the candidate PDCCH328communications. In some aspects, the UE may select a subset of the PDCCH328candidate resources for decoding based on the channel response and/or other channel measurements. In some instances, the UE may determine a metric based on the channel response and/or channel measurements associated with the plurality of DMRSs330. The UE may utilize the metric to determine whether to decode a particular candidate PDCCH328communication of the one or more candidate PDCCH328communications.

In some aspects, a UE (e.g., the UE115,120, or600) may decode the PDCCH communication (e.g., a PDCCH communication received based on the monitoring of the time/frequency resources300). The UE may decode the PDCCH328communication based on a metric associated with the plurality of DMRSs330satisfying a threshold. In some aspects, the UE may select a second set of PDCCH328candidate resources for decoding from the first set of PDCCH328candidate resources based on the metric. The UE may decode the PDCCH328communication (e.g., the candidate PDCCH328communication intended for the UE) from the second set of PDCCH328candidate resources. The second set of PDCCH328candidate resources may have a higher probability of including a PDCCH328communication intended for the UE than the PDCCH328candidate resources that are not included in the second set of PDCCH328candidate resources. By attempting to decode the smaller second set of PDCCH328candidate resources rather than the larger first set of PDCCH328candidate resources, the UE may conserve power and/or computing resources.

In some aspects, the UE may determine the metric based on one or more channel responses and/or channel measurements associated with the plurality of DMRSs330. For example, in some instances the metric may be based on a ratio of a summation of a first set of channel coefficients associated with the plurality of DMRSs330to a summation of a second set of channel coefficients associated with the plurality of DMRSs330. Additionally or alternatively, the UE may determine the metric based on a ratio of an absolute value of a summation of channel coefficients associated with the plurality of DMRSs330to an absolute value of a summation of a subset (e.g., a second set) of DMRSs330of the plurality of DMRS330. Additionally or alternatively, the UE may determine the metric based on a ratio of a summation of a first set of values associated with an addition of channel coefficients of adjacent DMRSs330(e.g., DMRSs that are carried via adjacent DMRS frequency subchannels312) to a summation of a second set of values associated with a difference in channel coefficients of the adjacent DMRSs330. DMRSs330that are carried via adjacent DMRS frequency subchannels312may be separated by a number of frequency subchannels312. In some aspects, the frequency subchannels312of the adjacent DMRSs330may be separated by a number (e.g., 1, 2, 3, 4, 5, or more) of frequency subchannels312. For example, the adjacent DMRSs330may be separated by 4 frequency subchannels312. As shown inFIG.3, resource element group310(1) may include 12 frequency subchannels312(0) . . .312(11). Subchannel312(0) may carry a DMRS330while adjacent subchannels312(4) and312(8) are each separated by 4 frequency subchannels312. The channel coefficient may be associated with the communication channel between the UE and the network unit. The channel coefficient may represent an estimation of the channel quality. For example, the channel coefficient may be a ratio of the DMRS330received by the UE to the DMRS330(e.g., a known reference signal) transmitted by the network unit to the UE.

In some aspects, the UE may determine the metric based on equation (1) below:

In equation (1), a may represent the metric used to select the second set of PDCCH328candidate resources from the first set of PDCCH328candidate resources. h[i] may represent the channel coefficient associated with the DMRS330having the index i and h[i-n] may represent the channel coefficient associated with the DMRS330having the index i-n. Further, h[i] and h[i-n] may represent DMRSs330that are carried via adjacent frequency subchannels312, where n represents the number of frequency subchannels312separating adjacent DMRSs330. In some aspects, the frequency subchannels312of the adjacent DMRSs330may be separated by a number (e.g., 1, 2, 3, 4, 5, or more) of frequency subchannels. For example, as shown inFIG.3, the adjacent DMRSs330may be separated by 4 frequency subchannels312(e.g., n=4). The resource elements in frequency subchannels312between the adjacent DMRSs330may be the PDCCH328candidate resources (e.g., the DMRS330resource elements may be interlaced in the frequency domain with the PDCCH328candidate resource elements). For example, the plurality of DMRSs330may be associated with frequency subchannels312(0),312(4), and312(8), etc. The PDCCH328candidate resources may be associated with frequency subchannels312(1),312(2),312(3),312(5),312(6),312(7),312(9),312(10), and312(11), etc.

FIG.4is a flow diagram of a wireless communication method400according to some aspects of the present disclosure. Actions of the communication method400can be executed by a computing device (e.g., a processor, processing circuit, and/or other suitable component) of a communication device or other suitable means for performing the actions. For example, a wireless communication device, such as the UE115, UE120, or UE600, may utilize one or more components, such as the processor602, the memory604, the PDCCH decoding module608, the transceiver610, the modem612, and the one or more antennas616, to execute aspects of method400.

At action402, a UE (e.g., the UE115, UE120, or UE600) may monitor PDCCH candidate resources for a PDCCH communication intended for the UE from a network unit. In this regard, the UE may monitor time/frequency resources for a PDCCH communication intended for the UE. The PDDCH communication may be intended for the UE based on an identifier (e.g., a radio network temporary identifier (RNTI)) associated with the UE. A network unit (e.g., the BS105, the CU1210, the DU1230, the RU1240, and/or network unit700) may configure the UE (e.g., configure via RRC signaling) with one or more control resource sets (CORESETs) in one or more frequency sub-bands (e.g., one or more frequency channels and/or sub-channels). A CORESET may include a set of frequency resources over a number of symbols in time. The network unit may configure the UE with one or more search spaces (e.g., time/frequency resource in the downlink resource grid that may carry the PDCCH communication intended for the UE) for PDCCH monitoring based on the one or more CORESETs. The UE may perform blind decoding in the search spaces to search for DCI information from the network unit. For example, the network unit may configure the UE with the frequency sub-bands, the CORESETs, and/or the PDCCH search spaces via RRC configurations. Accordingly, the UE may perform blind decoding in one or more search spaces that may be configured via RRC signaling. The network unit (e.g., the BS105, the CU1210, the DU1230, the RU1240, or the RU1240) may transmit a plurality of PDCCH communications (e.g., a first set of PDCCH communications) intended for multiple UEs in the time/frequency resources associated with the one or more search spaces configured for the UE. The plurality of PDCCH communications transmitted by the network unit may include the first PDCCH intended for the UE.

At action404, the UE may receive DMRSs. In this regard, the UE may receive a plurality of DMRSs from the network unit. The plurality of DMRSs may assist the UE in decoding information from the PDCCH communication. The network unit may include the plurality of DMRSs in the time/frequency resources associated with the one or more search spaces to assist the UE in channel estimation and/or PDCCH decoding.

At action406, the UE may perform channel estimation on the DMRSs. Upon receiving one or more candidate PDCCH communications from the network unit in the one or more search spaces, the UE may estimate a channel response from the associated DMRSs, perform demodulation of the candidate PDCCH communications based on an estimated channel response, and/or decode data from the candidate PDCCH communications. In some aspects, the UE may select a subset of the PDCCH candidate resources for decoding based on the channel response and/or other channel measurements.

At action408, the UE may determine a selection metric to select a second smaller set of PDCCH candidates from the larger first set of PDCCH candidates for decoding. In some aspects, the UE may determine the second set of PDCCH candidate resources based on the metric associated with the DMRSs satisfying a threshold. In this regard, the threshold may be based on a power capacity of the UE, a power consumption of the UE, and/or computing/memory resources associated with the UE. A PDCCH candidate resource of the first set of PDCCH candidate resources may be included in the second set of PDCCH candidate resources based on the metric associated with the DMRSs adjacent to the PDCCH candidate resource elements satisfying the threshold. The UE may reduce the set of PDCCH candidate resources for decoding in order to reduce power consumption and computing resources associated with the UE. In some aspects, the UE may perform decoding on the second set of PDCCH candidate resources using any suitable method. For example, the UE may perform successive cancellation list decoding and/or successive cancellation decoding on the second set of PDCCH candidate resources. In this regard, the UE may utilize multiple thresholds. The UE may select a particular decoding technique based on the value of the metric relative to the multiple thresholds. For example, if the metric is less than (or equal to) a first threshold, the UE may skip decoding; if the metric is greater than (or equal to) the first threshold and less than (or equal to) a second threshold, the UE may utilize successive cancellation list decoding; and if the metric is greater than (or equal to) the second threshold, the UE may utilize successive cancellation decoding. Other combinations of thresholds and/or decoding technique may be utilized in accordance with the present disclosure.

In some instances, the UE may determine one or more thresholds for the metric. For example, the UE may determine a first threshold of the metric and a second threshold of the metric. The second threshold may be greater in value than the first metric. In some aspects, the UE may determine the first threshold and/or the second threshold based on simulations that predict the probability of correctly decoding the PDCCH communication. In some aspects, the first threshold and/or the second threshold may be preprogrammed and/or stored in the UE. In some aspects, the UE may receive an indicator indicating the values of the first threshold and/or the second threshold from a network unit (e.g., BS105, the CU1210, the DU1230, the RU1240, and/or network unit700). In this regard, the UE may receive the indicator indicating the values of the first threshold and/or the second threshold from the network unit via radio resource control (RRC) messaging, downlink control information (DCI), a medium access control-control element (MAC-CE), or other suitable communication.

At action408, the UE may compare the channel coefficient to a first threshold. If the channel coefficient associated with the DMRS is less than the metric (e.g., a), the PDCCH candidate in resources adjacent to the DMRS resources may be excluded from the second set of PDCCH candidate resources.

At410, the UE may skip decoding of the PDCCH candidate based on the PDCCH candidate in resources adjacent to the DMRS resources being excluded from the second set of PDCCH candidate resources.

At action412, the UE may compare the channel coefficient to a second threshold. If a channel coefficient associated with a DMRS is greater than or equal to the first threshold but less than the second threshold, the PDCCH candidate in resources adjacent to the DMRS resources may be decoded using successive cancellation list decoding or other suitable decoding method. If a channel coefficient associated with a DMRS is greater than or equal to the second threshold, the PDCCH candidate in resources adjacent to the DMRS resources may be decoded using successive cancellation decoding or other suitable decoding method.

At action414, the UE may perform successive cancellation list decoding of the PDCCH candidate. The UE may successfully decode the PDCCH communication intended for the UE. In this regard, the UE may identify the PDCCH communication intended for it by decoding the second set of PDCCH candidate resources. The UE may use its radio network temporary identifier (RNTI) to decode the second set of PDCCH candidate resources. The RNTI may be used to demask the PDCCH communication from the second set of candidate PDCCH communications using the CRC. If no CRC error is detected, then the UE may determine that the candidate PDCCH communication carries the PDCCH communication intended for the UE. After successfully decoding the PDCCH communication, the UE may decode the downlink control information (DCI) carried via the PDCCH communication to obtain information about a physical downlink shared channel (PDSCH) resource allocation and/or a physical uplink shared channel (PUSCH) resource allocation.

At action416, the UE may perform successive cancellation decoding of the PDCCH candidate. The UE may successfully decode the PDCCH communication intended for the UE. In this regard, the UE may identify the PDCCH communication intended for it by decoding the second set of PDCCH candidate resources. The UE may use its radio network temporary identifier (RNTI) to decode the second set of PDCCH candidate resources. The RNTI may be used to demask the PDCCH communication from the second set of candidate PDCCH communications using the CRC. If no CRC error is detected, then the UE may determine that the candidate PDCCH communication carries the PDCCH communication intended for the UE. After successfully decoding the PDCCH communication, the UE may decode the downlink control information (DCI) carried via the PDCCH communication to obtain information about a physical downlink shared channel (PDSCH) resource allocation and/or a physical uplink shared channel (PUSCH) resource allocation

At action418, if the PDCCH candidate decoding is successful, the method may proceed to action422. If the decoding is unsuccessful, the method may proceed to action402to repeat the process on other PDCCH candidate resources.

At action420, the if the decoding is successful, the method may proceed to action424. If the decoding is unsuccessful, the method may proceed to action402to repeat the process on other PDCCH candidate resources.

At action422, the UE may transmit a communication (e.g., a transport block) to the network unit based on the PUSCH resource allocation.

At action424, the UE may transmit a communication (e.g., a transport block) to the network unit based on the PUSCH resource allocation.

FIG.5is a signaling diagram of a communication method500according to some aspects of the present disclosure. Actions of the communication method500can be executed by a computing device (e.g., a processor, processing circuit, and/or other suitable component) of a communication device or other suitable means for performing the actions. For example, a wireless communication device, such as the UE115, UE120, or UE600, may utilize one or more components, such as the processor602, the memory604, the PDCCH decoding module608, the transceiver610, the modem612, and the one or more antennas616, to execute aspects of method500.

At action502, the network unit105may transmit an indicator indicating an aggregation level to the UE115. In this regard, the network unit105may transmit the indicator indicating the aggregation level to the UE115via RRC signaling. The AL may indicate the number of control channel elements (CCEs) used for each PDCCH candidate. Each CCE may include six resource elements groups (REGs) or other suitable number of REGs, where a REG can be one physical RB in one symbol. The AL may be based on a quality of the channel. For example, if the UE is located near the network unit, the AL may be lower as compared to when the UE is farther from the network unit. The higher the AL, the more redundancy and more frequency diversity can be provided by the PDCCH transmission, and thus the more robust the PDCCH transmission may be.

At action504, the network unit105may transmit an indicator indicating a threshold associated with selecting a smaller set of PDCCH candidate resources for decoding from a larger set of PDCCH candidate resources. Additionally or alternatively, the UE115may determine the threshold. Additionally or alternatively, the threshold may be preconfigured and stored in the UE.

At action506, the network unit105may transmit PDCCH candidates in PDCCH candidate resources. The network unit105may configure the UE115via RRC signaling with one or more control resource sets (CORESETs) in one or more frequency sub-bands (e.g., one or more frequency channels and/or sub-channels). A CORESET may include a set of PDCCH candidate resources in frequency resources over a number of symbols in time. The network unit may configure the UE with one or more search spaces (e.g., time/frequency resource in the downlink resource grid that may carry the PDCCH communication intended for the UE) for PDCCH monitoring based on the one or more CORESETs.

At action508, the network unit105may transmit a plurality of DMRSs to the UE115. In this regard, the UE may receive a plurality of DMRSs from the network unit105. The plurality of DMRSs may assist the UE115in decoding information from the PDCCH candidate resources received at action506. The network unit105may include the plurality of DMRSs in the time/frequency resources associated with the one or more search spaces to assist the UE115in channel estimation and/or PDCCH decoding. The UE115may perform channel estimation on the DMRSs. Upon receiving one or more candidate PDCCH communications from the network unit105in the one or more search spaces, the UE115may estimate a channel response from the associated DMRSs.

At action510, the UE115may determine a metric associated with the channel responses of the DMRSs received at action508. The UE115may determine the metric based on equation (1).

At action512, the UE115may perform demodulation of the candidate PDCCH communications based on an estimated channel response, and/or decode data from the candidate PDCCH communications. In some aspects, the UE may select a subset of the PDCCH candidate resources for decoding based on the channel response and/or other channel measurements. In some instances, the UE may determine a metric based on the channel response and/or channel measurements associated with the plurality of DMRSs. The UE may utilize the metric to determine whether to decode a particular candidate PDCCH communication of the one or more candidate PDCCH communications.

At action514, if the decoding by the UE115is not successful, the method500will return to action506to determine whether to decode another PDCCH candidate resources based on the metric thresholds.

At action516, the UE115may transmit a communication to the network unit105based on successful PDCCH candidate decoding at action512.

FIG.6is a block diagram of an exemplary UE600according to some aspects of the present disclosure. The UE600may be the UE115or the UE120in the network100,200, or250as discussed above. As shown, the UE600may include a processor602, a memory604, a PDCCH decoding module608, a transceiver610including a modem subsystem612and a radio frequency (RF) unit614, and one or more antennas616. These elements may be coupled with each other and in direct or indirect communication with each other, for example via one or more buses.

The PDCCH decoding module608may be implemented via hardware, software, or combinations thereof. For example, the PDCCH decoding module608may be implemented as a processor, circuit, and/or instructions606stored in the memory604and executed by the processor602. In some aspects, the PDCCH decoding module608may be used to monitor a first set of physical downlink control channel (PDCCH) candidate resources for a PDCCH communication from the network unit700or the BS105, receive, from the network unit700or the BS105, a plurality of demodulation reference signals (DMRSs) and decode, based on a metric associated with the plurality of demodulation reference signals (DMRSs) satisfying a threshold, the PDCCH communication.

As shown, the transceiver610may include the modem subsystem612and the RF unit614. The transceiver610can be configured to communicate bi-directionally with other devices, such as the BSs105and/or the UEs115. The modem subsystem612may be configured to modulate and/or encode the data from the memory604and the according to a modulation and coding scheme (MCS), e.g., a low-density parity check (LDPC) coding scheme, a turbo coding scheme, a convolutional coding scheme, a digital beamforming scheme, etc. The RF unit614may be configured to process (e.g., perform analog to digital conversion or digital to analog conversion, etc.) modulated/encoded data from the modem subsystem612(on outbound transmissions) or of transmissions originating from another source such as a UE115or a BS105. The RF unit614may be further configured to perform analog beamforming in conjunction with the digital beamforming. Although shown as integrated together in transceiver610, the modem subsystem612and the RF unit614may be separate devices that are coupled together to enable the UE600to communicate with other devices.

The RF unit614may provide the modulated and/or processed data, e.g. data packets (or, more generally, data messages that may contain one or more data packets and other information), to the antennas616for transmission to one or more other devices. The antennas616may further receive data messages transmitted from other devices. The antennas616may provide the received data messages for processing and/or demodulation at the transceiver610. The antennas616may include multiple antennas of similar or different designs in order to sustain multiple transmission links. The RF unit614may configure the antennas616.

In some instances, the UE600can include multiple transceivers610implementing different RATs (e.g., NR and LTE). In some instances, the UE600can include a single transceiver610implementing multiple RATs (e.g., NR and LTE). In some instances, the transceiver610can include various components, where different combinations of components can implement RATs.

FIG.7is a block diagram of an exemplary network unit700according to some aspects of the present disclosure. The network unit700may be a BS105, the CU1210, the DU1230, or the RU1240, as discussed above. As shown, the network unit700may include a processor702, a memory704, a PDCCH decoding module708, a transceiver710including a modem subsystem712and a RF unit714, and one or more antennas716. These elements may be coupled with each other and in direct or indirect communication with each other, for example via one or more buses.

The memory704may include a cache memory (e.g., a cache memory of the processor702), RAM, MRAM, ROM, PROM, EPROM, EEPROM, flash memory, a solid state memory device, one or more hard disk drives, memristor-based arrays, other forms of volatile and non-volatile memory, or a combination of different types of memory. In some instances, the memory704may include a non-transitory computer-readable medium. The memory704may store instructions706. The instructions706may include instructions that, when executed by the processor702, cause the processor702to perform operations described herein, for example, aspects ofFIGS.2-5and8-9. Instructions706may also be referred to as code, which may be interpreted broadly to include any type of computer-readable statement(s).

The PDCCH decoding module708may be implemented via hardware, software, or combinations thereof. For example, the PDCCH decoding module708may be implemented as a processor, circuit, and/or instructions706stored in the memory704and executed by the processor702.

In some aspects, the PDCCH decoding module708may implement the aspects ofFIGS.2-5and8-9. For example, the PDCCH decoding module708may transmit, to a UE (e.g., UE115, UE120, or UE600), an indication of a set of physical downlink control channel (PDCCH) candidate resources, transmit, to the UE, a plurality of demodulation reference signals (DMRSs), and receive, from the UE based on a metric associated with the plurality of DMRSs, a communication.

Additionally or alternatively, the PDCCH decoding module708can be implemented in any combination of hardware and software, and may, in some implementations, involve, for example, processor702, memory704, instructions706, transceiver710, and/or modem712.

As shown, the transceiver710may include the modem subsystem712and the RF unit714. The transceiver710can be configured to communicate bi-directionally with other devices, such as the UEs115and/or600. The modem subsystem712may be configured to modulate and/or encode data according to a MCS, e.g., a LDPC coding scheme, a turbo coding scheme, a convolutional coding scheme, a digital beamforming scheme, etc. The RF unit714may be configured to process (e.g., perform analog to digital conversion or digital to analog conversion, etc.) modulated/encoded data from the modem subsystem712(on outbound transmissions) or of transmissions originating from another source such as a UE115or UE600. The RF unit714may be further configured to perform analog beamforming in conjunction with the digital beamforming. Although shown as integrated together in transceiver710, the modem subsystem712and/or the RF unit714may be separate devices that are coupled together at the network unit700to enable the network unit700to communicate with other devices.

The RF unit714may provide the modulated and/or processed data, e.g. data packets (or, more generally, data messages that may contain one or more data packets and other information), to the antennas716for transmission to one or more other devices. This may include, for example, a configuration indicating a plurality of sub-slots within a slot according to aspects of the present disclosure. The antennas716may further receive data messages transmitted from other devices and provide the received data messages for processing and/or demodulation at the transceiver710. The antennas716may include multiple antennas of similar or different designs in order to sustain multiple transmission links.

In some instances, the network unit700can include multiple transceivers710implementing different RATs (e.g., NR and LTE). In some instances, the network unit700can include a single transceiver710implementing multiple RATs (e.g., NR and LTE). In some instances, the transceiver710can include various components, where different combinations of components can implement RATs.

FIG.8is a flow diagram of a communication method800according to some aspects of the present disclosure. Aspects of the method800can be executed by a computing device (e.g., a processor, processing circuit, and/or other suitable component) of a wireless communication device or other suitable means for performing the aspects. For example, a wireless communication device, such as the UE115, UE120, or UE600may utilize one or more components to execute aspects of method800. The method800may employ similar mechanisms as in the networks100and200and the aspects and actions described with respect toFIGS.2-5. For example, a wireless communication device, such as the UE115, UE120, or UE600, may utilize one or more components, such as such as the processor602, the memory604, the PDDCH decoding module608, the transceiver610, the modem612, and the one or more antennas616, to execute aspects of the method800. As illustrated, the method800includes a number of enumerated aspects, but the method800may include additional aspects before, after, and in between the enumerated aspects. In some aspects, one or more of the enumerated aspects may be omitted or performed in a different order.

At action810, the method800includes a UE (e.g., the UE115,120, or600) monitoring a first set of physical downlink control channel (PDCCH) candidate resources for a PDCCH communication from a network unit. In this regard, the UE may monitor time/frequency resources for a PDCCH communication intended for the UE. The PDDCH communication may be intended for the UE based on an identifier (e.g., a radio network temporary identifier (RNTI)) associated with the UE. A network unit (e.g., the BS105, the CU1210, the DU1230, the RU1240, and/or network unit700) may configure the UE (e.g., configure via RRC signaling) with one or more control resource sets (CORESETs) in one or more frequency sub-bands (e.g., one or more frequency channels and/or sub-channels). A CORESET may include a set of frequency resources over a number of symbols in time. The network unit may configure the UE with one or more search spaces (e.g., time/frequency resource in the downlink resource grid that may carry the PDCCH communication intended for the UE) for PDCCH monitoring based on the one or more CORESETs. The UE may perform blind decoding in the search spaces to search for DCI information from the network unit. For example, the network unit may configure the UE with the frequency sub-bands, the CORESETs, and/or the PDCCH search spaces via RRC configurations. Accordingly, the UE may perform blind decoding in one or more search spaces that may be configured via RRC signaling. The network unit (e.g., the BS105, the CU1210, the DU1230, the RU1240, or the RU1240) may transmit a plurality of PDCCH communications (e.g., a first set of PDCCH communications) intended for multiple UEs in the time/frequency resources associated with the one or more search spaces configured for the UE. The plurality of PDCCH communications transmitted by the network unit may include the first PDCCH intended for the UE.

The number of PDCCH candidate resources searched by the UE may be based on an aggregation level (AL). The AL may indicate the number of control channel elements (CCEs) used for each PDCCH candidate. Each CCE may include six resource elements groups (REGs) or other suitable number of REGs, where a REG can be one physical RB in one symbol. The AL may be based on a quality of the channel. For example, if the UE is located near the network unit, the AL may be lower as compared to when the UE is farther from the network unit. The higher the AL, the more redundancy and more frequency diversity can be provided by the PDCCH transmission, and thus the more robust the PDCCH transmission may be.

The UE may attempt to blind decode a cyclic redundancy check (CRC) within the search spaces with an RNTI value (such as C-RNTI for UE-specific search spaces, or other RNTI types for common search spaces) using a trial-and-error approach of resource locations and parameters. This blind decoding method may consume finite resources associated with the UE. Such finite resources may be limited depending on per slot capabilities of the UE such as the number of PDCCH blind decoding candidates per slot and/or the number of CCEs that the UE may monitor per slot. Monitoring all of the PDCCH candidate resources for the PDCCH communication intended for the UE may consume more power and/or computing resources associated with the UE as compared to monitoring a subset of the PDCCH candidate resources. As described with reference to action830below, in accordance with the present disclosure the UE may select a subset of the PDCCH candidate resources for monitoring in order to reduce power and/or computing resources associated with the UE.

At action820, the method800includes a UE (e.g., the UE115,120, or600) receiving a plurality of demodulation reference signals (DMRSs) from the network unit. In this regard, the plurality of DMRSs may assist the UE in decoding information from the PDCCH communication. The network unit may include the plurality of DMRSs in the time/frequency resources associated with the one or more search spaces to assist the UE in channel estimation and/or PDCCH decoding.

Upon receiving one or more candidate PDCCH communications from the network unit in the one or more search spaces, the UE may estimate a channel response from the associated DMRSs, perform demodulation of the candidate PDCCH communications based on an estimated channel response, and/or decode data from the candidate PDCCH communications. In some aspects, the UE may select a subset of the PDCCH candidate resources for decoding based on the channel response and/or other channel measurements. In some instances, the UE may determine a metric based on the channel response and/or channel measurements associated with the plurality of DMRSs. The UE may utilize the metric to determine whether to decode a particular candidate PDCCH communication of the one or more candidate PDCCH communications, as described at action830.

At action830, the method800includes a UE (e.g., the UE115,120, or600) decoding the PDCCH communication (e.g., a PDCCH communication received based on the monitoring at action810). The UE may decode the PDCCH communication based on a metric associated with the plurality of DMRSs satisfying a threshold. In some aspects, the UE may select a second set of PDCCH candidate resources for decoding from the first set of PDCCH candidate resources based on the metric. The UE may decode the PDCCH communication (e.g., the candidate PDCCH communication intended for the UE) from the second set of PDCCH candidate resources. The second set of PDCCH candidate resources may have a higher probability of including a PDCCH communication intended for the UE than the PDCCH candidate resources that are not included in the second set of PDCCH candidate resources. By attempting to decode the smaller second set of PDCCH candidate resources rather than the larger first set of PDCCH candidate resources, the UE may conserve power and/or computing resources.

In some aspects, the UE may determine the metric based on one or more channel responses and/or channel measurements associated with the plurality of DMRSs. For example, in some instances the metric may be based on a ratio of a summation of a first set of channel coefficients associated with the plurality of DMRSs to a summation of a second set of channel coefficients associated with the plurality of DMRSs. Additionally or alternatively, the UE may determine the metric based on a ratio of an absolute value of a summation of channel coefficients associated with the plurality of DMRSs to an absolute value of a summation of a subset (e.g., a second set) of DMRSs of the plurality of DMRS. Additionally or alternatively, the UE may determine the metric based on a ratio of a summation of a first set of values associated with an addition of channel coefficients of adjacent DMRSs (e.g., DMRSs that are carried via adjacent DMRS frequency subchannels) to a summation of a second set of values associated with a difference in channel coefficients of the adjacent DMRSs. DMRSs that are carried via adjacent DMRS frequency subchannels may be separated by a number of frequency subchannels. In some aspects, the frequency subchannels of the adjacent DMRSs may be separated by a number (e.g., 1, 2, 3, 4, 5, or more) of frequency subchannels. For example, the adjacent DMRSs may be separated by 4 frequency subchannels. The channel coefficient may be associated with the communication channel between the UE and the network unit. The channel coefficient may represent an estimation of the channel quality. For example, the channel coefficient may be a ratio of the DMRS received by the UE to the DMRS (e.g., a known reference signal) transmitted by the network unit to the UE.

In some aspects, the UE may determine the metric based on equation (1) below:

In equation (1), a may represent the metric used to select the second set of PDCCH candidate resources from the first set of PDCCH candidate resources. h[i] may represent the channel coefficient associated with the DMRS having the index i. and h[i-n] may represent the channel coefficient associated with the DMRS having the index i-n. Further, h[i] and h[i-n] may represent DMRSs that are carried via adjacent frequency subchannels, where n represents the number of frequency subchannels separating adjacent DMRSs. In some aspects, the frequency subchannels of the adjacent DMRSs may be separated by a number (e.g., 1, 2, 3, 4, 5, or more) of frequency subchannels. For example, the adjacent DMRSs may be separated by 4 frequency subchannels (e.g., n=4). The resource elements in frequency subchannels between the adjacent DMRSs may be the PDCCH candidate resources (e.g., the DMRS resource elements may be interlaced in the frequency domain with the PDCCH candidate resource elements). For example, the plurality of DMRSs may be associated with frequency subchannels having resource indexes i-0, i-4, i-8, i-12, etc. The PDCCH candidate resources may be associated with frequency subchannels having resource indexes i-1, i-2, i-3, i-5, i-6, i-7, i-9, i-10, i-11, etc.

In some aspects, the UE may determine the second set of PDCCH candidate resources based on the metric associated with the DMRSs satisfying a threshold. In this regard, the threshold may be based on a power capacity of the UE, a power consumption of the UE, and/or computing/memory resources associated with the UE. A PDCCH candidate resource of the first set of PDCCH candidate resources may be included in the second set of PDCCH candidate resources based on the metric associated with the DMRSs adjacent to the PDCCH candidate resource elements satisfying the threshold. For example, if a channel coefficient associated with a DMRS is greater than or equal to the metric (e.g., a), the PDCCH candidate in resources adjacent to the DMRS resources may be included in the second set of PDCCH candidate resources. Conversely, if the channel coefficient associated with the DMRS is less than the metric (e.g., a), the PDCCH candidate in resources adjacent to the DMRS resources may be excluded from the second set of PDCCH candidate resources. The UE may perform decoding on the PDCCH candidate resources in the second set of PDCCH candidate resources and exclude the PDCCH candidate resources from decoding that are not in the second set of PDCCH candidate resources. In this way, the UE may reduce the set of PDCCH candidate resources for decoding in order to reduce power consumption and computing resources associated with the UE.

In some aspects, the UE may perform decoding on the second set of PDCCH candidate resources using any suitable method. For example, the UE may perform successive cancellation list decoding and/or successive cancellation decoding on the second set of PDCCH candidate resources. In this regard, the UE may utilize multiple thresholds. The UE may select a particular decoding technique based on the value of the metric relative to the multiple thresholds. For example, if the metric is less than (or equal to) a first threshold, the UE may skip decoding; if the metric is greater than (or equal to) the first threshold and less than (or equal to) a second threshold, the UE may utilize successive cancellation list decoding; and if the metric is greater than (or equal to) the second threshold, the UE may utilize successive cancellation decoding. Other combinations of thresholds and/or decoding technique may be utilized in accordance with the present disclosure.

In some instances, the UE may determine one or more thresholds for the metric. For example, the UE may determine a first threshold of the metric and a second threshold of the metric. The second threshold may be greater in value than the first metric. In some aspects, the UE may determine the first threshold and/or the second threshold based on simulations that predict the probability of correctly decoding the PDCCH communication. In some aspects, the first threshold and/or the second threshold may be preprogrammed and/or stored in the UE. In some aspects, the UE may receive an indicator indicating the values of the first threshold and/or the second threshold from a network unit (e.g., BS105, the CU1210, the DU1230, the RU1240, and/or network unit700). In this regard, the UE may receive the indicator indicating the values of the first threshold and/or the second threshold from the network unit via radio resource control (RRC) messaging, downlink control information (DCI), a medium access control-control element (MAC-CE), or other suitable communication.

In some aspects, if a channel coefficient associated with a DMRS is less than the first threshold and the second threshold, the PDCCH candidate in resources adjacent to the DMRS resources may be excluded from decoding by the UE. If a channel coefficient associated with a DMRS is greater than or equal to the first threshold but less than the second threshold, the PDCCH candidate in resources adjacent to the DMRS resources may be decoded using successive cancellation list decoding or other suitable decoding method. If a channel coefficient associated with a DMRS is greater than or equal to the second threshold, the PDCCH candidate in resources adjacent to the DMRS resources may be decoded using successive cancellation decoding or other suitable decoding method. Additionally or alternatively, if a channel coefficient associated with a DMRS is greater than or equal to the first threshold but less than the second threshold, the PDCCH candidate in resources adjacent to the DMRS resources may be decoded using successive cancellation decoding or other suitable decoding method. If a channel coefficient associated with a DMRS is greater than or equal to the second threshold, the PDCCH candidate in resources adjacent to the DMRS resources may be decoded using successive cancellation list decoding or other suitable decoding method.

In some aspects, the UE may successfully decode the PDCCH communication intended for the UE. In this regard, the UE may identify the PDCCH communication intended for it by decoding the second set of PDCCH candidate resources. The UE may use its radio network temporary identifier (RNTI) to decode the second set of PDCCH candidate resources. The RNTI may be used to demask the PDCCH communication from the second set of candidate PDCCH communications using the CRC. If no CRC error is detected, then the UE may determine that the candidate PDCCH communication carries the PDCCH communication intended for the UE. After successfully decoding the PDCCH communication, the UE may decode the downlink control information (DCI) carried via the PDCCH communication to obtain information about a physical downlink shared channel (PDSCH) resource allocation and/or a physical uplink shared channel (PUSCH) resource allocation. The UE may receive a communication (e.g., a transport block) from the network unit based on the PDSCH resource allocation. The UE may transmit a communication (e.g., a transport block) to the network unit based on the PUSCH resource allocation.

FIG.9is a flow diagram of a communication method900according to some aspects of the present disclosure. Aspects of the method900can be executed by a computing device (e.g., a processor, processing circuit, and/or other suitable component) of a wireless communication device or other suitable means for performing the aspects. For example, a wireless communication device, such as the BS105, the CU1210, the DU1230, the RU1240, and/or network unit700may utilize one or more components to execute aspects of method900. The method900may employ similar mechanisms as in the networks100and200and the aspects and actions described with respect toFIGS.2-5. For example, a wireless communication device, such as the BS105or network unit700, may utilize one or more components, such as such as the processor702, the memory704, the PDDCH decoding module708, the transceiver710, the modem712, and the one or more antennas716, to execute aspects of the method900. As illustrated, the method900includes a number of enumerated aspects, but the method900may include additional aspects before, after, and in between the enumerated aspects. In some aspects, one or more of the enumerated aspects may be omitted or performed in a different order.

At action910, the method900includes a network unit (e.g., the BS105, the CU1210, the DU1230, the RU1240, and/or network unit700) transmitting an indication of a set of physical downlink control channel (PDCCH) candidate resources to a UE (e.g., the UE115,120, or600). In this regard, the UE may monitor time/frequency resources for a PDCCH communication intended for the UE. The PDDCH communication may be intended for the UE based on an identifier (e.g., a radio network temporary identifier (RNTI)) associated with the UE. A network unit (e.g., the BS105, the CU1210, the DU1230, the RU1240, and/or network unit700) may configure the UE (e.g., configure via RRC signaling) with one or more control resource sets (CORESETs) in one or more frequency sub-bands (e.g., one or more frequency channels and/or sub-channels). A CORESET may include a set of frequency resources over a number of symbols in time. The network unit may configure the UE with one or more search spaces (e.g., time/frequency resource in the downlink resource grid that may carry the PDCCH communication intended for the UE) for PDCCH monitoring based on the one or more CORESETs. The UE may perform blind decoding in the search spaces to search for DCI information from the network unit. For example, the network unit may configure the UE with the frequency sub-bands, the CORESETs, and/or the PDCCH search spaces via RRC configurations. Accordingly, the UE may perform blind decoding in one or more search spaces that may be configured via RRC signaling. The network unit (e.g., the BS105, the CU1210, the DU1230, the RU1240, or the RU1240) may transmit a plurality of PDCCH communications (e.g., a first set of PDCCH communications) intended for multiple UEs in the time/frequency resources associated with the one or more search spaces configured for the UE. The plurality of PDCCH communications transmitted by the network unit may include the first PDCCH intended for the UE.

The number of PDCCH candidate resources searched by the UE may be based on an aggregation level (AL). The AL may indicate the number of control channel elements (CCEs) used for each PDCCH candidate. Each CCE may include six resource elements groups (REGs) or other suitable number of REGs, where a REG can be one physical RB in one symbol. The AL may be based on a quality of the channel. For example, if the UE is located near the network unit, the AL may be lower as compared to when the UE is farther from the network unit. The higher the AL, the more redundancy and more frequency diversity can be provided by the PDCCH transmission, and thus the more robust the PDCCH transmission may be.

The UE may attempt to blind decode a cyclic redundancy check (CRC) within the search spaces with an RNTI value (such as C-RNTI for UE-specific search spaces, or other RNTI types for common search spaces) using a trial-and-error approach of resource locations and parameters. This blind decoding method may consume finite resources associated with the UE. Such finite resources may be limited depending on per slot capabilities of the UE such as the number of PDCCH blind decoding candidates per slot and/or the number of CCEs that the UE may monitor per slot. Monitoring all of the PDCCH candidate resources for the PDCCH communication intended for the UE may consume more power and/or computing resources associated with the UE as compared to monitoring a subset of the PDCCH candidate resources. In accordance with the present disclosure the UE may select a subset of the PDCCH candidate resources for monitoring in order to reduce power and/or computing resources associated with the UE.

At action920, the method900includes the network unit transmitting a plurality of demodulation reference signals (DMRSs) to the UE. In this regard, the plurality of DMRSs may assist the UE in decoding information from the PDCCH communication. The network unit may include the plurality of DMRSs in the time/frequency resources associated with the one or more search spaces to assist the UE in channel estimation and/or PDCCH decoding.

Upon receiving one or more candidate PDCCH communications from the network unit in the one or more search spaces, the UE may estimate a channel response from the associated DMRSs, perform demodulation of the candidate PDCCH communications based on an estimated channel response, and/or decode data from the candidate PDCCH communications. In some aspects, the UE may select a subset of the PDCCH candidate resources for decoding based on the channel response and/or other channel measurements. In some instances, the UE may determine a metric based on the channel response and/or channel measurements associated with the plurality of DMRSs. The UE may utilize the metric to determine whether to decode a particular candidate PDCCH communication of the one or more candidate PDCCH communications.

The UE may decode the PDCCH communication based on a metric associated with the plurality of DMRSs satisfying a threshold. In some aspects, the UE may select a second set of PDCCH candidate resources for decoding from the first set of PDCCH candidate resources based on the metric. The UE may decode the PDCCH communication (e.g., the candidate PDCCH communication intended for the UE) from the second set of PDCCH candidate resources. The second set of PDCCH candidate resources may have a higher probability of including a PDCCH communication intended for the UE than the PDCCH candidate resources that are not included in the second set of PDCCH candidate resources. By attempting to decode the smaller second set of PDCCH candidate resources rather than the larger first set of PDCCH candidate resources, the UE may conserve power and/or computing resources.

In some aspects, the UE may determine the metric based on one or more channel responses and/or channel measurements associated with the plurality of DMRSs. For example, in some instances the metric may be based on a ratio of a summation of a first set of channel coefficients associated with the plurality of DMRSs to a summation of a second set of channel coefficients associated with the plurality of DMRSs. Additionally or alternatively, the UE may determine the metric based on a ratio of an absolute value of a summation of channel coefficients associated with the plurality of DMRSs to an absolute value of a summation of a subset (e.g., a second set) of DMRSs of the plurality of DMRS. Additionally or alternatively, the UE may determine the metric based on a ratio of a summation of a first set of values associated with an addition of channel coefficients of adjacent DMRSs (e.g., DMRSs that are carried via adjacent DMRS frequency subchannels) to a summation of a second set of values associated with a difference in channel coefficients of the adjacent DMRSs. DMRSs that are carried via adjacent DMRS frequency subchannels may be separated by a number of frequency subchannels. In some aspects, the frequency subchannels of the adjacent DMRSs may be separated by a number (e.g., 1, 2, 3, 4, 5, or more) of frequency subchannels. For example, the adjacent DMRSs may be separated by 4 frequency subchannels. The channel coefficient may be associated with the communication channel between the UE and the network unit. The channel coefficient may represent an estimation of the channel quality. For example, the channel coefficient may be a ratio of the DMRS received by the UE to the DMRS (e.g., a known reference signal) transmitted by the network unit to the UE.

In some aspects, the UE may determine the metric based on equation (1) below:

In equation (1), a may represent the metric used to select the second set of PDCCH candidate resources from the first set of PDCCH candidate resources. h[i] may represent the channel coefficient associated with the DMRS having the index i. and h[i-n] may represent the channel coefficient associated with the DMRS having the index i-n. Further, h[i] and h[i-n] may represent DMRSs that are carried via adjacent frequency subchannels, where n represents the number of frequency subchannels separating adjacent DMRSs. In some aspects, the frequency subchannels of the adjacent DMRSs may be separated by a number (e.g., 1, 2, 3, 4, 5, or more) of frequency subchannels. For example, the adjacent DMRSs may be separated by 4 frequency subchannels (e.g., n=4). The resource elements in frequency subchannels between the adjacent DMRSs may be the PDCCH candidate resources (e.g., the DMRS resource elements may be interlaced in the frequency domain with the PDCCH candidate resource elements). For example, the plurality of DMRSs may be associated with frequency subchannels having resource indexes i-0, i-4, i-8, i-12, etc. The PDCCH candidate resources may be associated with frequency subchannels having resource indexes i-1, i-2, i-3, i-5, i-6, i-7, i-9, i-10, i-11, etc.

In some aspects, the UE may determine the second set of PDCCH candidate resources based on the metric associated with the DMRSs satisfying a threshold. In this regard, the threshold may be based on a power capacity of the UE, a power consumption of the UE, and/or computing/memory resources associated with the UE. A PDCCH candidate resource of the first set of PDCCH candidate resources may be included in the second set of PDCCH candidate resources based on the metric associated with the DMRSs adjacent to the PDCCH candidate resource elements satisfying the threshold. For example, if a channel coefficient associated with a DMRS is greater than or equal to the metric (e.g., a), the PDCCH candidate in resources adjacent to the DMRS resources may be included in the second set of PDCCH candidate resources. Conversely, if the channel coefficient associated with the DMRS is less than the metric (e.g., a), the PDCCH candidate in resources adjacent to the DMRS resources may be excluded from the second set of PDCCH candidate resources. The UE may perform decoding on the PDCCH candidate resources in the second set of PDCCH candidate resources and exclude the PDCCH candidate resources from decoding that are not in the second set of PDCCH candidate resources. In this way, the UE may reduce the set of PDCCH candidate resources for decoding in order to reduce power consumption and computing resources associated with the UE.

In some aspects, the UE may perform decoding on the second set of PDCCH candidate resources using any suitable method. For example, the UE may perform successive cancellation list decoding and/or successive cancellation decoding on the second set of PDCCH candidate resources. In this regard, the UE may utilize multiple thresholds. The UE may select a particular decoding technique based on the value of the metric relative to the multiple thresholds. For example, if the metric is less than (or equal to) a first threshold, the UE may skip decoding; if the metric is greater than (or equal to) the first threshold and less than (or equal to) a second threshold, the UE may utilize successive cancellation list decoding; and if the metric is greater than (or equal to) the second threshold, the UE may utilize successive cancellation decoding. Other combinations of thresholds and/or decoding technique may be utilized in accordance with the present disclosure.

In some instances, the UE may determine one or more thresholds for the metric. For example, the UE may determine a first threshold of the metric and a second threshold of the metric. The second threshold may be greater in value than the first metric. In some aspects, the UE may determine the first threshold and/or the second threshold based on simulations that predict the probability of correctly decoding the PDCCH communication. In some aspects, the first threshold and/or the second threshold may be preprogrammed and/or stored in the UE. In some aspects, the UE may receive an indicator indicating the values of the first threshold and/or the second threshold from a network unit (e.g., BS105, the CU1210, the DU1230, the RU1240, and/or network unit700). In this regard, the UE may receive the indicator indicating the values of the first threshold and/or the second threshold from the network unit via radio resource control (RRC) messaging, downlink control information (DCI), a medium access control-control element (MAC-CE), or other suitable communication.

In some aspects, if a channel coefficient associated with a DMRS is less than the first threshold and the second threshold, the PDCCH candidate in resources adjacent to the DMRS resources may be excluded from decoding by the UE. If a channel coefficient associated with a DMRS is greater than or equal to the first threshold but less than the second threshold, the PDCCH candidate in resources adjacent to the DMRS resources may be decoded using successive cancellation list decoding or other suitable decoding method. If a channel coefficient associated with a DMRS is greater than or equal to the second threshold, the PDCCH candidate in resources adjacent to the DMRS resources may be decoded using successive cancellation decoding or other suitable decoding method. Additionally or alternatively, if a channel coefficient associated with a DMRS is greater than or equal to the first threshold but less than the second threshold, the PDCCH candidate in resources adjacent to the DMRS resources may be decoded using successive cancellation decoding or other suitable decoding method. If a channel coefficient associated with a DMRS is greater than or equal to the second threshold, the PDCCH candidate in resources adjacent to the DMRS resources may be decoded using successive cancellation list decoding or other suitable decoding method.

At action930, the method900includes the network unit receiving a communication from the UE based on the metric associated with the plurality of DMRSs. In some aspects, the UE may successfully decode the PDCCH communication intended for the UE. In this regard, the UE may identify the PDCCH communication intended for it by decoding the second set of PDCCH candidate resources. The UE may use its radio network temporary identifier (RNTI) to decode the second set of PDCCH candidate resources. The RNTI may be used to demask the PDCCH communication from the second set of candidate PDCCH communications using the CRC. If no CRC error is detected, then the UE may determine that the candidate PDCCH communication carries the PDCCH communication intended for the UE. After successfully decoding the PDCCH communication, the UE may decode the downlink control information (DCI) carried via the PDCCH communication to obtain information about a physical downlink shared channel (PDSCH) resource allocation and/or a physical uplink shared channel (PUSCH) resource allocation. The UE may receive a communication (e.g., a transport block) from the network unit based on the PDSCH resource allocation. The UE may transmit a communication (e.g., a transport block) to the network unit based on the PUSCH resource allocation.

Further aspects of the present disclosure include the following:

Aspect 1 includes a method of wireless communication performed by a user equipment (UE), the method comprising monitoring a first set of physical downlink control channel (PDCCH) candidate resources for a first PDCCH communication from a network unit; receiving, from the network unit, a plurality of demodulation reference signals (DMRSs); and decoding, based on a metric associated with the plurality of demodulation reference signals (DMRSs) satisfying a threshold, the first PDCCH communication.

Aspect 2 includes the method of aspect 1, further comprising selecting a second set of PDCCH candidate resources from the first set of PDCCH candidate resources based on the metric, wherein the second set of PDCCH candidate resources includes a resource associated with the first PDCCH communication.

Aspect 3 includes the method of any of aspects 1-2, wherein the metric satisfying the threshold comprises the metric being greater than the threshold; and the decoding the first PDCCH communication comprises successive cancellation decoding of the first PDCCH communication from the second set of PDCCH candidate resources based on the metric being greater than the threshold.

Aspect 4 includes the method of any of aspects 1-3, wherein the decoding the first PDCCH communication comprises at least one of decoding the first PDCCH communication using successive cancellation list decoding of the first PDCCH communication from the second set of PDCCH candidate resources based on the metric being greater than a first threshold; or decoding the first PDCCH communication using successive cancellation decoding of the first PDCCH communication from the second set of PDCCH candidate resources based on the metric being greater than a second threshold, the second threshold being greater than the first threshold.

Aspect 5 includes the method of any of aspects 1-4, wherein the metric comprises a ratio of a summation of a first set of channel coefficients associated with the plurality of DMRSs to a summation of a second set of channel coefficients associated with the plurality of DMRSs.

Aspect 6 includes the method of any of aspects 1-5, wherein the metric comprises a ratio of an absolute value of a summation of channel coefficients associated with the plurality of DMRSs to an absolute value of a summation of a subset of DMRSs of the plurality of DMRSs.

Aspect 7 includes the method of any of aspects 1-6, wherein the metric comprises a ratio of a summation of a first set of values associated with an addition of channel coefficients of adjacent DMRSs to a summation of a second set of values associated with a difference in channel coefficients of the adjacent DMRSs.

Aspect 8 includes the method of any of aspects 1-7, wherein the adjacent DMRSs are separated by four resource elements.

Aspect 9 includes the method of any of aspects 1-8, further comprising transmitting, to the network unit in response to decoding the PDCCH, a communication.

Aspect 10 includes the method of any of aspects 1-9, further comprising receiving, from the network unit via a radio resource control (RRC) message, an indicator indicating an aggregation level associated with the first set of PDCCH candidate resources, wherein a number of the plurality of DMRSs is based on the aggregation level.

Aspect 11 includes the method of any of aspects 1-10, further comprising receiving, from the network unit via a radio resource control (RRC) message, an indicator indicating the threshold.

Aspect 12 includes the method of any of aspects 1-11, wherein the threshold is based on a power capacity associated with the UE.

Aspect 13 includes a method of wireless communication performed by a network unit, comprising transmitting an indication of a set of physical downlink control channel (PDCCH) candidate resources; transmitting a plurality of demodulation reference signals (DMRSs); and receiving, based on a metric associated with the plurality of DMRSs, a communication.

Aspect 14 includes the method of aspect 13, further comprising transmitting a threshold associated with the metric, wherein the receiving the communication is based on the metric satisfying the threshold.

Aspect 15 includes the method of any of aspects 13-14, further comprising transmitting, via a radio resource control (RRC) message, an indicator indicating an aggregation level associated with the set of PDCCH candidates, wherein a number of the plurality of DMRSs is based on the aggregation level.

Aspect 16 includes a non-transitory computer-readable medium storing one or more instructions for wireless communication, the one or more instructions comprising one or more instructions that, when executed by one or more processors of a user equipment (UE), cause the UE to perform any one of aspects 1-12.

Aspect 17 includes a non-transitory computer-readable medium storing one or more instructions for wireless communication, the one or more instructions comprising one or more instructions that, when executed by one or more processors of an apparatus for wireless communications, cause the apparatus to perform any one of aspects 13-15.

Aspect 18 includes a user equipment (UE) comprising one or more means to perform any one or more of aspects 1-12.

Aspect 19 includes an apparatus for wireless communications comprising one or more means to perform any one or more of aspects 13-15.

Aspect 20 includes a user equipment (UE) comprising a memory, a transceiver and at least one processor coupled to the memory and the transceiver, wherein the UE is configured to perform any one or more of aspects 1-12.

Aspect 21 includes an apparatus for wireless communications comprising a memory, a transceiver and at least one processor coupled to the memory and the transceiver, wherein the apparatus is configured to perform any one or more of aspects 13-15.