Patent ID: 12225565

DETAILED DESCRIPTION

Certain terms are used throughout the description and following claims to refer to particular components. As one skilled in the art will appreciate, manufacturers may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms “include” and “comprise” are used in an open-ended fashion, and thus should be interpreted to mean “include, but not limited to . . . ”. Also, the term “couple” is intended to mean either an indirect or direct electrical connection. Accordingly, if one device is coupled to another device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections. The making and using of the embodiments of the disclosure are discussed in detail below. It should be appreciated, however, that the embodiments can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative, and do not limit the scope of the disclosure. Some variations of the embodiments are described. Throughout the various views and illustrative embodiments, like reference numbers are used to designate like elements.

The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. Note that the 3GPP specifications described herein are used to teach the spirit of the invention, and the invention is not limited thereto. Reference will now be made in detail to some embodiments of the invention, examples of which are illustrated in the accompanying drawings.

FIG.1illustrates a system diagram of a new radio (NR) beamforming wireless system100with spatial relation switching in accordance with embodiments of the current invention. Beamforming milli-meter (mmWave) mobile communication network100comprises a base station BS101and a user equipment UE102. The mmWave cellular network uses directional communications with beamformed transmission and can support up to multi-gigabit data rate. Directional communications are achieved via digital and/or analog beamforming, wherein multiple antenna elements are applied with multiple sets of beamforming weights to form multiple beams. In the example ofFIG.1, BS101is directionally configured with multiple cells, and each cell is covered by a set of TX/RX beams. For example, for uplink transmission, cell110is covered by a set of five BS RX beams RX #1, RX #2, RX #3, RX #4, and RX #5. The collection of the BS RX beams RX #1-RX #5 covers an entire service area of cell110. Similarly, UE102may also apply beamforming to form multiple UE TX beams, e.g., TX #1-TX #5. For beamformed access, both ends of a link need to know which beamformers to use, e.g., a serving beam pair link (BPL)130for uplink communication between BS101(using RX #3) and UE102(using TX #1). BS101may also be referred to as an access point (AP), an access terminal, a Node-B, an eNodeB, an eNB, a gNodeB, a gNB, or by other terminology used in the art. UE102may be a mobile phone, a laptop computer, a device carried in a vehicle, an Internet of Things (IoT) device, etc.

In 5G NR, each BS control beam broadcasts minimum amount of cell-specific and beam-specific information via synchronization signal (SS) blocks (SSB). Additionally, spatial relation is signaled by the network to UE to indicate the Quasi Co-Location (QCL)-type between uplink channel resource and reference signals. The uplink channels include physical uplink control channel (PUCCH) and physical uplink shared channel (PUSCH). Two kinds of spatial relation are defined. A first kind of {QCL-TypeA, QCL-TypeB, QCL-TypeC} is related to channel statistical character. A second kind of {QCL-TypeD} is related to spatial TX parameters which are the parameters related to FR2 only. The spatial relation information indicates the spatial filter (e.g., TX beam) to be used by UE for the corresponding PUCCH or PUSCH or sounding reference signal (SRS) transmission. The network can indicate the target spatial relation to UE to change the QCL-type by radio resource control (RRC) configuration, media access control (MAC)-control element (CE) activation, and downlink control information (DCI) indication.

As depicted inFIG.1, a spatial relation information, e.g., a spatial relation between a spatial TX filter for a dedicated uplink resource and a spatial filter for a reference signal resource, can be indicated by RRC signaling or RRC+MAC CE. In one example (110), a SpatialRelationInfoList, which contains one or more PUCCH-SpatialRelationInfo Information Elements (IEs), is configured in a dedicated PUCCH resource configuration via RRC signaling. Each PUCCH-SpatialRelationInfo IE can include a synchronization signal block (SSB) resource indicator (SSBRI), a channel state information reference signal (CSI-RS) resource indicator (CRI), or a sounding reference signal (SRS) resource indicator (SRI), to indicate the spatial filter (e.g., the UE TX beam) to be used by UE associated to the corresponding PUCCH transmission. When the number of PUCCH-SpatialRelationInfo IEs in SpatialRelationInfoList is more than one, then a MAC CE is used to point to one of the PUCCH-SpatialRelationInfo IEs for indicating spatial relation information for a dedicated PUCCH resource. In the example ofFIG.1, the SpatialRelationInfoList110contains at most four PUCCH-SpatialRelationInfo IEs including SSB #1, CSI #3, CSI #5, and SRS #4. A MAC CE120including a four-bit bitmap and a PUCCH resource ID for PUCCH spatial relation activation, with a second bit of the bitmap having value 1, is then used to indicate that UE102can assume a spatial relation between a spatial filter for CSI #3 and a spatial filter for UE PUCCH transmission on a dedicated PUCCH resource indicated by the PUCCH resource ID.

FIG.1further shows an example of spatial relation switching when the spatial relation is configured to be QCLed with a downlink reference signal (DL RS) or an uplink sounding reference signal (UL SRS), where, the terminology ‘QCLed’ can also be referred to as associated. At first, the network configures the current spatial relation to request the UE to use TX #1 (the active spatial filter) to transmit the signals. The network used the RX #3 to receive the transmission signals (e.g., BPL130). After a while, the network detects that UE using TX #3 is better than using TX #1. Then the network configures the new spatial relation to request the UE to switch its TX beam to TX #3 (the target spatial filter). The network can use its RX #1 to receive the signals from UE (e.g., BPL140). The new target spatial relation is configured to be QCLed with a DL RS or UL SRS. The spatial relation information can be provided by the network via RRC signaling, MAC CE activation or DCI indication.

In one novel aspect, a method of performing spatial relation switching in NR system is proposed as depicted in140. In one embodiment, the configured spatial relation is QCLed to the source of a DL RS, such as SSB or CSI-RS (step 1). In this QCLed relation, the active spatial relation switching condition shall differentiate known and unknown situation (step 2). In known condition, when UE receives the spatial relation configuration, the UE parses this configuration and executes the fine timing tracking on the new configured QCLed RS. After that, the UE switches its spatial relation to the new configuration. In unknown condition, in addition to the above procedure, the UE also executes the L1-RSRP measurement after UE parses the spatial relation configuration and before the fine timing tracking. In another embodiment, the configured spatial relation can be QCLed to the root source of an UL SRS (step 1). In this QCLed relation, the active spatial relation switching condition does not need to differentiate known and unknown situation (step 2). When UE receives the spatial relation configuration, the UE parses this configuration and switches the spatial relation following with the configured SRS index.

The proposed spatial relation switching shall apply for PUSCH, PUCCH, and SRS transmission (step 3). In PUCCH, the MAC based spatial relation switch shall be defined. In PUSCH, spatial relation activation shall only follow the related PUCCH or SRS spatial relation switch procedure. In periodic SRS, the RRC based spatial relation switch shall be defined. In semi-persistent SRS, the MAC based spatial relation switch shall be defined. In aperiodic SRS, the DCI based spatial relation switch shall be defined. The aperiodic SRS should always associate with a known spatial relation.

FIG.2is a simplified block diagram of a base station and a user equipment that carry out certain embodiments of the present invention. BS201has an antenna array211having multiple antenna elements that transmits and receives radio signals, one or more RF transceiver modules212, coupled with the antenna array, receives RF signals from antenna211, converts them to baseband signal, and sends them to processor213. RF transceiver212also converts received baseband signals from processor213, converts them to RF signals, and sends out to antenna211. Processor213processes the received baseband signals and invokes different functional modules to perform features in BS201. Memory214stores program instructions and data215to control the operations of BS201. BS201also includes multiple function modules and circuitry that carry out different tasks in accordance with embodiments of the current invention.

Similarly, UE202has an antenna231, which transmits and receives radio signals. A RF transceiver module232, coupled with the antenna, receives RF signals from antenna231, converts them to baseband signals and sends them to processor233. RF transceiver232also converts received baseband signals from processor233, converts them to RF signals, and sends out to antenna231. Processor233processes the received baseband signals and invokes different functional modules to perform features in UE202. Memory234stores program instructions and data235to control the operations of UE202. UE202also includes multiple function modules and circuitry that carry out different tasks in accordance with embodiments of the current invention.

The functional modules and circuits can be implemented and configured by hardware, firmware, software, and any combination thereof. For example, BS201comprises a beam management module220, which further comprises a beamforming circuit221, a beam monitor222, a config and scheduling circuit223, and an beam config and switching handling circuit224. Beamforming circuit221may belong to part of the RF chain, which applies various beamforming weights to multiple antenna elements of antenna211and thereby forming various beams. Beam monitor222monitors received radio signals and performs measurements of the radio signals over the various beams. Config and scheduling circuit223schedules uplink transmission for UEs and configures radio resources with spatial relation info and switching to UEs for uplink transmission. Beam config and switching handling circuit224handles spatial relation switching procedure.

Similarly, UE202comprises a beam management module240, which further comprises a control and configuration circuit241, a beamforming circuit242, a beam measurement circuit243, a measurement reporting circuit244, and a spatial relation switching handling circuit245. Control and configuration circuit241receives configuration information from the serving BS via RRC signaling and/or MAC CE and/or PDCCH DCI. The configuration information may comprise uplink resource and spatial relation information. Beamforming circuit242may belong to part of the RF chain, which applies various beamforming weights to multiple antenna elements of antenna231and thereby forming various beams based on the UL control beam indication from the network. Beam measurement circuit243perform L1 RSRP measurements over configured measurement objects. Beam measurement reporting circuit244reports measurement results. Spatial relation switching handling circuit245handles spatial relation switching procedure, and determines whether to perform beam sweeping and L1 measurements depending on whether the configured spatial relation is known or unknown.

FIG.3illustrates examples of definition of spatial relation Quasi-Co-Located (QCLed) source reference signals (RSs). InFIG.3(a), a PUSCH channel310is configured a spatial relation to be QCLed with SRS index #0320, and this SRS #0320is already configured to be QCLed with a DL SSB #0330. As a result, the source of PUSCH channel310's QCLed spatial relation is DL RS, e.g., SSB #0330. The DL RS can be either SRS or CSI-RS. InFIG.3(b), a PUSCH channel340is configured a spatial relation to be QCLed with SRS index #0350, and this SRS #0350has no other QCLed relation being configured. Basically, this SRS can be configured with ‘beamManagement’. As a result, the source of PUSCH channel340's QCLed spatial relation is UL SRS, e.g., SRS #0350.

FIG.4illustrates one embodiment of a spatial relation switching procedure when the configured uplink target spatial relation is QCLed to a DL RS. When the QCLed source is a DL RS, such as SSB or CSI-RS, the known or unknown condition of the configured target spatial relation for spatial relation switching needs to be defined. The configured target spatial relation is known if the following conditions are met: 1) the spatial relation switch is within [X]s of last transmission of beam reporting or beam measurement for the QCLed RS of the target spatial relation, such as X=1.28s; 2) the UE has previously sent at least one measurement report for the QCLed RS of the target spatial relation; 3) the spatial relation shall remain detectable during the spatial relation switching period, e.g., the SNR of the QCLed RS and the root QCLed SSB/CSI-RS is always larger than a threshold, e.g., −3 dB, during the overall duration for spatial relation switching; and 4) the SNR of the RS which the target spatial relation is configured to be QCLed is greater than a threshold, e.g., >−3 dB. Otherwise, the configured target spatial relation is unknown.

In the example ofFIG.4, in step410, a UE receives a SpatialRelationInfoList and optionally Measurement Object (MO) from a serving BS in NR network. In step420, the UE performs L1-RSRP measurement and reporting based on the MO. If the configured spatial relation is known, when network receives the UE's measurement reporting, the network may configure the UE to switch to a new spatial relation. When UE receives the spatial relation switch command, the UE only needs to decode the command and optionally execute one-shot fine timing tracking. After that, the UE will finish the active spatial relation switch, e.g., using the new spatial relation for uplink channel transmission. Otherwise, if the configured spatial relation is unknown, the network may configure the UE to switch to a new spatial relation without any measurement information. When UE receives the spatial relation switch command, the UE needs to decode the command. After that, the UE executes RX beam sweeping and performs L1-RSRP measurements to find the best RX beam and then do the one-shot fine timing tracking. After that, the UE will finish the active spatial relation switch, e.g., using the new spatial relation for uplink channel transmission.

Accordingly, in step430, the UE receives spatial relation configuration from the network to switch to a new spatial relation. In step440, the UE decodes the spatial relation configuration. If the spatial relation is known, then the UE skips step450and optionally performs one-shot timing tracking in step460. In step470, the UE finishes the spatial relation switch procedure and switches to the new spatial relation. Otherwise, if the spatial relation is unknown, in step450, the UE performs L1-RSRP measurement. In step460, the UE optionally performs one-shot timing tracking. In step470, the UE finishes the spatial relation switch procedure and switches to the new spatial relation. Note that when the spatial relation is unknown, the UE should execute the L1-RSRP measurement (RX beam sweeping) to train the downlink spatial domain filter before transmitting the uplink signals with the same spatial domain transmission filter. During the training phase, the UE only has the previous spatial relation information (which UE adopted before receiving the switch command) and also this information is known to network. Therefore, the UE shall be allowed to transmit signals with the previous spatial domain transmission filter, but the signal quality cannot be guaranteed before UE finishes the active spatial relation switching procedure.

FIG.5illustrates one embodiment of a spatial relation switching procedure when the configured uplink spatial relation is QCLed to an SRS. After some QCLed links, the uplink spatial relation shall be QCLed with SRS with its usage configured as ‘beamManagement’. In this case, the UE does not need any additional beam sweeping procedure. Thus, the procedure does not differentiate known and unknown condition when the uplink spatial relation is QCLed to an SRS. In step510, the network configures a spatial relation list, e.g., a SpatialRelationInfoList to the UE. In step520, the network directly configures a new spatial relation with SRS index to the UE. In step530, the UE parses the spatial relation configuration, e.g., QCLed to an uplink SRS index. In step540, the UE follows the same beam as this uplink SRS.

FIG.6illustrates one embodiment of PUCCH spatial relation switching in accordance with one novel aspect of the present invention. In step610, a UE receives spatial relation configuration, which comprises up to eight (8) spatial relations, for instance, via an RRC signaling, for an uplink control channel PUCCH. In step620, one of the spatial relations is activated via MAC CE for the uplink control channel PUCCH, which is a MAC based active spatial relation configuration. In step630, the UE transmits the PUCCH using a RX spatial domain filter as a reception beam of a DL RS (SSB or CSI-RS) if UE supports the beamCorrespondence capability with 1 or a transmission beam of an UL SRS. As illustrated earlier inFIG.4, when the active spatial relation is configured to switch to a DL RS, the UE requirements will be different for known spatial relation and unknown spatial relation. On the other hand, when active spatial relation is configured to switch to an UL SRS, the only consideration is the MAC CE parsing time.

FIG.7illustrates embodiments of PUSCH spatial relation switching in accordance with one novel aspect of the present invention. PUSCH spatial relation is explicitly demonstrated and follows either the PUCCH or SRS spatial relation depending on the DCI command received, i.e., DCI format 0_0 or 0_1. As depicted inFIG.7(a), when DCI format 0_0 is received, PUSCH always follows the same spatial domain transmission filter as for PUCCH. In step710, the UE receives DCI format 0_0 activation for PUSCH with the lowest ID within the active UL BWP of the cell, which is a DCI based active spatial relation configuration. In step720, the UE transmits the PUSCH following the same spatial domain filter as a reception beam of a DL RS (SSB or CSI-RS) if UE supports the beamCorrespondence capability with 1 or a transmission beam of an UL SRS, as activated by DCI 0_0.

As depicted inFIG.7(b), when DCI format 0_1 is configured, the UE shall transmit PUSCH using the same antenna ports as the SRS port(s) in the SRS resource(s) indicated by SRI(s). In step730, the UE receives DCI format 0_1 activation for PUSCH, with the indicated SRS in slot n is associated with the most recent transmission of SRS resource identified by the SRI, which is a DCI based active spatial relation configuration. In step740, the UE transmits the PUSCH using the same antenna ports as the SRS port(s) in the SRS resource(s) indicated by SRI(s), as activated by DCI 0_1. PUSCH spatial relation activation shall only follow the related PUCCH or SRS spatial relation switch procedure.

FIG.8illustrates embodiments of SRS spatial relation switching in accordance with one novel aspect of the present invention. The SRS resources can be periodic, semi-persistent, or aperiodic. InFIG.8(a), a spatial relation list for periodic SRS is configured, for instance, by RRC signaling in step810. The UE transmits the periodic SRS with the target spatial relation in step820. If the SRS is associated with another uplink SRS, then the UE will directly use the same beam for this uplink SRS. The UE does not need the additional RX beam sweeping time. If the SRS is associated with a DL RS, then the active spatial relation switch shall differentiate between known and unknown condition.

InFIG.8(b), a spatial relation list for semi-persistent SRS is configured, for instance, by RRC signaling in step830. Semi-persistent SRS is activated by MAC-CE in step840. If the SRS is associated with another uplink SRS, UE will directly use the same beam for this uplink SRS. UE does not need the additional Rx beam sweeping time. When network configures semi-persistent SRS transmission, if the SRS is associated with a DL RS, then the active spatial relation switch shall differentiate between known and unknown condition. The UE transmits the semi-persistent SRS with the target spatial relation in step850.

InFIG.8(c), a spatial relation list for aperiodic SRS is configured, for instance, by RRC signaling in step860. Aperiodic SRS is triggered/activated by DCI command in step870. For aperiodic SRS, generally, it could be regarded as an urgent sounding behavior. It means the network doesn't want additional beam training time and needs this sounding information as soon as possible. The time interval between the DCI command and the aperiodic SRS transmission is a very short time duration. Thus, the aperiodic SRS should always associate with a known spatial relation. The UE transmits the aperiodic SRS with the target spatial relation in step880.

FIG.9is a flow chart of a method of performing spatial relation switching in accordance with embodiments of the current invention. In step901, a UE receives a spatial relation configuration to switch to a target spatial relation for an uplink channel in a new radio (NR) network. According to different embodiments, the spatial relation configuration is received via a radio resource control (RRC) or MAC or DCI signaling. The spatial relation configuration indicates a spatial filter of the uplink channel is Quasi-Co-Located (QCLed) with one or more spatial filters of one or more downlink reference signals (DL RSs). In step902, the UE determines whether the target spatial relation is known or unknown based on a list of predefined conditions. In step903, the UE switches to the target spatial relation when the target spatial relation is known, otherwise the UE performs spatial filter training for a QCLed DL RS when the target spatial relation is unknown.

A UE can be configured to implement various embodiments of the above disclosure. The UE can include a processor, a memory, and an RF module as illustrated inFIG.2. The UE can optionally include other components, such as input and output devices, additional CPU or signal processing circuitry, and the like. Accordingly, the UE may be capable of performing other additional functions, such as executing application programs, and processing alternative communication protocols.

The processes and functions described herein can be implemented as a computer program which, when executed by one or more processors, can cause the one or more processors to perform the respective processes and functions. The computer program may be stored or distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with, or as part of, other hardware. The computer program may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems. For example, the computer program can be obtained and loaded into an apparatus, including obtaining the computer program through physical medium or distributed system, including, for example, from a server connected to the Internet.

The computer program may be accessible from a computer-readable medium providing program instructions for use by or in connection with a computer or any instruction execution system. A computer readable medium may include any apparatus that stores, communicates, propagates, or transports the computer program for use by or in connection with an instruction execution system, apparatus, or device. The computer-readable medium can be magnetic, optical, electronic, electromagnetic, infrared, or semiconductor system (or apparatus or device) or a propagation medium. The computer-readable medium may include a computer-readable non-transitory storage medium such as a semiconductor or solid state memory, magnetic tape, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), a magnetic disk and an optical disk, and the like. The computer-readable non-transitory storage medium can include all types of computer readable medium, including magnetic storage medium, optical storage medium, flash medium and solid state storage medium.

While aspects of the present disclosure have been described in conjunction with the specific embodiments thereof that are proposed as examples, alternatives, modifications, and variations to the examples may be made. Accordingly, embodiments as set forth herein are intended to be illustrative and not limiting. There are changes that may be made without departing from the scope of the claims set forth below.