WO2022077485A1

WO2022077485A1 - User equipment, base station, and method of common beam determination

Info

Publication number: WO2022077485A1
Application number: PCT/CN2020/121651
Authority: WO
Inventors: Maoxin Tian; Jia SHENG; Tian LI
Original assignee: JRD Communication Shenzhen Ltd
Current assignee: JRD Communication Shenzhen Ltd
Priority date: 2020-10-16
Filing date: 2020-10-16
Publication date: 2022-04-21
Anticipated expiration: 2023-04-16
Also published as: CN116420415A; CN116420415B

Abstract

A user equipment (UE), a base station, and methods of common beam determination are provided. The method of common beam determination performed by the UE includes determining, by the UE, one or more transmission configuration indication (TCI) states from a base station, wherein the one or more TCI states comprises one or more reference signals (RSs), determining, by the UE, one or more beams from the base station, wherein the one or more beams are used for a multi-beam operation, identifying, by the UE, one or more common beams from the one or more beams according to the one or more RSs, and using, by the UE, the one or more common beams for both a downlink (DL) reception and an uplink (UL) transmission in the multi-beam operation. This defines a unified common beam indication for DL and UL in multi-beam operation.

Description

USER EQUIPMENT, BASE STATION, AND METHOD OF COMMON BEAM DETERMINATION

BACKGROUND OF DISCLOSURE

1. Field of the Disclosure

The present disclosure relates to the field of wireless communication systems operating in multiple-input multiple-output (MIMO) systems, and more particularly, to a user equipment (UE) , a base station, and methods of common beam determination, which can enhance a common beam design for data and control transmission/reception for downlink (DL) and uplink (UL) in multi-beam transmission.

2. Description of the Related Art

Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These wireless communication systems may be capable of supporting communication with multiple users by sharing available system resources (e.g., time, frequency, and power) . Examples of such multiple-access systems include fourth generation (4G) systems such as long term evolution (LTE) systems and fifth generation (5G) systems which may be referred to as new radio (NR) systems. These systems may employ technologies such as code division multiple access (CDMA) , time division multiple access (TDMA) , frequency division multiple access (FDMA) , orthogonal frequency division multiple access (OFDMA) , or discrete Fourier transform-spread-OFDM (DFT-S-OFDM) . A wireless multiple-access communications system may include a number of base stations or network access nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipments (UEs) .

A wireless communication network may include a base station that can support communication for a UE. The UE may communicate with the base station via downlink (DL) and uplink (UL) . The DL refers to a communication link from the base station to the UE, and the UL refers to a communication link from the UE to the base station.

Multiple-input multiple-output (MIMO) is an effective approach to enhance capacity of a radio link due to multiplexing of both transmit and receive antennas. MIMO refers to a practical technique for sending and receiving more than one data signal simultaneously over the same radio channel, which improves a performance of spectral efficiency greatly. However, DL and UL beam indication mechanisms in multi-beam transmission operating in MIMO systems are still open issues.

Therefore, there is a need for a user equipment (UE) , a base station, and methods of common beam determination, which can solve issues in the prior art, define a unified common beam indication for data and control transmission/reception for DL and UL in the multi-beam operation, enhance a common beam design for data and control transmission/reception for DL and UL in the multi-beam operation, provide a good communication performance, and/or provide high reliability.

SUMMARY

An object of the present disclosure is to propose a user equipment (UE) , a base station, and methods of common beam determination, which can solve issues in the prior art, define a unified common beam indication for data and control transmission/reception for DL and UL in the multi-beam operation, enhance a common beam design for data and control transmission/reception for DL and UL in the multi-beam operation, provide a good communication performance, and/or provide high reliability.

In a first aspect of the present disclosure, a method of common beam determination performed by a user equipment (UE) comprises determining, by the UE, one or more transmission configuration indication (TCI) states from a base station, wherein the one or more TCI states comprises one or more reference signals (RSs) ; determining, by the UE, one or more beams from the base station, wherein the one or more beams are used for a multi-beam operation; identifying, by the UE, one or more common beams from the one or more beams according to the one or more RSs; and using, by the UE, the one or more common beams for both a downlink (DL) reception and an uplink (UL) transmission in the multi-beam operation.

In an embodiment of the present disclosure, the one or more common beams are indicated according to the one or more RSs associated to the one or more beams.

In an embodiment of the present disclosure, there is only one TCI state configured by the base station.

In an embodiment of the present disclosure, when there is only one RS in the one TCI state, the RS is related to the common beam for both the DL reception and/or the UL transmission in the multi-beam operation.

In an embodiment of the present disclosure, the RS comprises a DL RS and/or a UL RS.

In an embodiment of the present disclosure, the DL RS comprises a channel state information (CSI) RS.

In an embodiment of the present disclosure, the UL RS comprises a sounding reference signal (SRS) .

In an embodiment of the present disclosure, the common beam is indicated using a radio resource control (RRC) signaling and a media access control (MAC) control element (CE) singling.

In an embodiment of the present disclosure, the one TCI state is activated by a MAC CE signaling, a downlink control information (DCI) field is applied to indicate a beam in the one TCL state.

In an embodiment of the present disclosure, when the indicated beam in the one TCI state is not the common beam and if there is other common beam associated with the RSs in the TCI state, the UE uses the common beam with a lowest index in the TCI state for both the DL reception and the UL transmission in the multi-beam operation.

In an embodiment of the present disclosure, when the UE is configured with the beams associated with the RSs in the TCI states, the method further comprises determining, by the UE, a mapping between the beams and the RSs.

In an embodiment of the present disclosure, identifying, by the UE, the one or more common beams from the one or more beams according to the one or more RSs comprises: identifying, by the UE, the one or more common beams from the beams according to the mapping between the beams and the RSs.

In an embodiment of the present disclosure, the RSs comprise parameters, and the parameters comprise at least one of the followings: bit numbers; or slots of a UL signal received by the base station.

In an embodiment of the present disclosure, determining, by the UE, the mapping between the beams and the RSs is through system information.

In an embodiment of the present disclosure, identifying, by the UE, the one or more common beams from the beams according to the mapping between the beams and the RSs comprises: performing, by the UE, a beam measurement on the beams according to the mapping between the beams and the RSs; reporting, by the UE, the beam measurement to the base station; receiving, by the UE, a first indication of the one or more common beams from the base station, wherein the first indication of the one or more common beams comprise a first selection of the one or more common beams by the base station according to the beam measurement.

In an embodiment of the present disclosure, identifying, by the UE, the one or more common beams from the beams according to the mapping between the beams and the RSs comprises: performing, by the UE, a UL beam sweeping; transmitting, by the UE, UL RSs configured in the TCI states to the base station; and receiving, by the UE, a second indication of the one or more common beams from the base station, wherein the second indication of the one or more common beams comprise a second selection of the one or more common beams by the base station according to the UL RSs.

In an embodiment of the present disclosure, the one or more common beams depend on an associated UL RS, where the UL RS is the most recently received signal at the base station.

In an embodiment of the present disclosure, the TCI states are activated by a MAC CE signaling, a downlink control information (DCI) field is applied to indicate one or more beams in the one or more TCI states in a scheduling time.

In an embodiment of the present disclosure, when the one or more indicated beams in the one or more TCI states in the scheduling time are not one or more common beams, the UE uses a latest indicated common beam before the scheduling time for both the DL reception and the UL transmission in the multi-beam operation.

In an embodiment of the present disclosure, the method is performed in a joint common beam indication mode, a separate common beam indication mode, a hybrid common beam indication mode, or a default common beam indication mode.

In an embodiment of the present disclosure, when the method is performed in the joint common beam indication mode, the UE uses the same common beam for both the DL reception and the UL transmission in the multi-beam operation.

In an embodiment of the present disclosure, for the joint common beam indication mode, both the DL reception and the UL transmission are indicated by only one common beam, when there is only one RS in the single TCI state, the RS is related to the common beam for both the DL reception and the UL transmission.

In an embodiment of the present disclosure, the RS is the DL RS or the UL RS.

In an embodiment of the present disclosure, for the joint common beam indication mode, combination of K beams associated with flags is used to identify the common beams, where K is greater than 1.

In an embodiment of the present disclosure, if several beams of the K beams are common beams, a corresponding flag value of each of the several beams is used to determine the common beams.

In an embodiment of the present disclosure, if the DL RS provides the common beam, the base station selects a beam associated with a bit number in a flag through a reported CSI from the UE, if the UL RS provides the common beam, the base station selects a beam associated with the bit number in the flag through a SRS from the UE, the selected beam depends on an associated uplink signal, where the uplink signal is the most recently received signal at the base station, comprising the report CSI or the SRS, and the combination of K beams associated with flags is used to identify whether the indicated beam is the common beam or not.

In an embodiment of the present disclosure, for the joint common beam indication mode, each beam is for a time slot unit, the base station selects a beam through the most recently received signal comprising a report CSI or a SRS, each signal received by the base station corresponds to a slot, and a corresponding relationship between the slot and the beam is used to identify whether the selected beam is the common beam or not.

In an embodiment of the present disclosure, when the method is performed in the separate common beam indication mode, the UE separately applies an independent common beam for both the DL reception and the UL transmission in the multi-beam operation.

In an embodiment of the present disclosure, the one or more RSs in M TCIs provide a quasi co-location (QCL) assumption for the DL reception, the one or more RSs in N TCIs provide a spatial filter for the UL transmission, and one or more candidate common beams for the DL reception and the UL transmission are included in the M TCIs and the N TCIs, respectively, where M is greater than or equal to 1, and N is greater than or equal to 1.

In an embodiment of the present disclosure, for the DL reception or the UL transmission, when there is only one TCI state, the TCL state comprises only one RS to provide the QCL assumption for the DL reception or the spatial filter for the UL transmission, the beam associate with the RS is the common beam for the DL reception or the UL transmission in the multi-beam operation.

In an embodiment of the present disclosure, when the RSs are associated with multiple K DL beams and L UL beams included in the TCI states, the RSs are configured to indicate whether K times L beam pairs comprise the one or more common beams or not.

In an embodiment of the present disclosure, when the method is performed in the separate common beam indication mode and when there is only one TCI state comprising only one RS to provide a reference for QCL or spatial filter, the beam associate with the RS is the common beam for the DL reception or the UL transmission.

In an embodiment of the present disclosure, when the method is performed in the separate common beam indication mode and when the base station performs a beam sweeping, the UE makes a beam measurement, after measuring the beam, the UE transmits the UL RS to the base station in slot positions associated with the measured beam, and the base station measures the UL RS and selects a best UL beam to obtain a beam pair.

In an embodiment of the present disclosure, when the method is performed in the separate common beam indication mode and when there is only one TCI state, both DL beams associated with DL RSs and UL beams associated with UL RSs are configured in the TCI state.

In an embodiment of the present disclosure, when the method is performed in the separate common beam indication mode and when there is only one TCI state and if both an indicated DL beam and an indicated UL beam of an indicated beam pair are not DL common beam and UL common beam, the UE uses the common beam with a lowest beam pair index in the TCI state for both the DL reception and the UL transmission in the multi-beam operation.

In an embodiment of the present disclosure, when the method is performed in the separate common beam indication mode and when there is only one TCI state and if an indicated beam pair is not the common beam, but an indicated DL beam or an indicated UL beam of the indicated beam pair is a DL common beam or a UL common beam, the UE uses the common beam with the lowest beam pair index in the TCI state for DL and UL indication, where the lowest beam pair comprises the DL or UL common beam related to the indicated common beam pair.

In an embodiment of the present disclosure, when the method is performed in the separate common beam indication mode, when the UE is configured with multiple TCI states, when the common beam is not present in an indicated TCI state, and if both an indicated DL beam and an indicated UL beam of an indicated beam pair are not a DL common beam and an UL common beam, the UE performs the DL reception and the UL transmission using the latest indicated common beam before a scheduling time.

In an embodiment of the present disclosure, when the method is performed in the separate common beam indication mode, when the UE is configured with multiple TCI states, when the common beam is not present in an indicated TCI state, and if a DL beam or a UL beam of an indicated common beam pair is the common beam, the UE performs the DL reception and the UL transmission using the latest indicated common beam before a scheduling time, where the indicated common beam comprises the DL or UL common beam related to the indicated common beam pair in the scheduling time.

In an embodiment of the present disclosure, when the method is performed in the hybrid common beam indication mode, the UE uses a first type of common beam and a second type of common beam, where the first type of common beam is configured for both the DL reception and the UL transmission in the multi-beam operation, and the second type of common beam is only configured for the DL reception or the UL transmission in the multi-beam operation.

In an embodiment of the present disclosure, the one or more RSs configured in the one or more TCLs provide the first type of common beam and the second type of common beam.

In an embodiment of the present disclosure, when the RSs are associated with multiple K DL beams, L UL beams, S beams applied for both the DL reception and the UL transmission included in the TCI states, the RSs are configured to indicate whether K times L plus S beam pairs comprise the one or more common beams or not.

In an embodiment of the present disclosure, the first type of common beam and the second type of common beam have different priorities.

In an embodiment of the present disclosure, the priority of the first type of common beam is greater than the second type of common beam.

In an embodiment of the present disclosure, when the common beam in the TCI state is not present, the first type of common beam and the second type of common beam who are configured with higher priority included in the TCI state which indicated in the latest scheduling time is considered to be the common beam.

In an embodiment of the present disclosure, a time window is configured by the base station for the UE to distinguish whether the common beam or the common beam pair is valid or not.

In an embodiment of the present disclosure, if there are not only the first type of common beams included within the window time, the UE uses the common beam with a lowest index in the TCI state for both the DL reception and the UL transmission in the multi-beam operation; and/or if there are only the second type of common beams included within the window time, the UE uses the common beam with a lowest beam pair index in the TCI state for both the DL reception and the UL transmission in the multi-beam operation.

In an embodiment of the present disclosure, when the method is performed in the hybrid common beam indication mode, K times L beam pairs are obtained by combination of K DL beams associated with multiple DL RSs and L UL beams associated with multiple UL RSs, and there are total K times L plus S beams/pairs that can be used for the DL reception and the UL transmission.

In an embodiment of the present disclosure, when the method is performed in the hybrid common beam indication mode, if there is a selected beam with index from a first beam to a sth beam, the UE measures the beam with RSs to provide the common beam only for the DL reception or the UL transmission; and/or if there is a selected beam with index from a first beam pair to a K times Lth beam pair, the UE measures the beam with the RSs to provide the common beam for both the DL reception and the UL transmission.

In an embodiment of the present disclosure, when the method is performed in the default common beam indication mode, the UE uses one or more default common beams as one or more common beams when DL and UL default beams are aligned.

In an embodiment of the present disclosure, the one or more default common beams comprise the latest common beam with the lowest index which is included in one of scheduling times.

In a second aspect of the present disclosure, a method of common beam determination performed by a base station comprises configuring, by the base station, one or more transmission configuration indication (TCI) states to a user equipment (UE) , wherein the one or more TCI states comprises one or more reference signals (RSs) ; configuring, by the base station, one or more beams to the UE, wherein the one or more beams are used for a multi-beam operation; identifying, by the base station, one or more common beams from the one or more beams according to the one or more RSs; and using, by the base station, the one or more common beams for both a downlink (DL) transmission and an uplink (UL) reception in the multi-beam operation.

In an embodiment of the present disclosure, when there is only one RS in the one TCI state, the RS is related to the common beam for both the DL transmission and/or the UL reception in the multi-beam operation.

In an embodiment of the present disclosure, when the indicated beam in the one TCI state is not the common beam and if there is other common beam associated with the RSs in the TCI state, the UE uses the common beam with a lowest index in the TCI state for both DL reception and UL transmission in the multi-beam operation.

In an embodiment of the present disclosure, identifying, by the base station, the one or more common beams from the one or more beams according to the one or more RSs comprises: identifying, by the base station, the one or more common beams from the beams according to the mapping between the beams and the RSs.

In an embodiment of the present disclosure, determining, by the base station, the mapping between the beams and the RSs is through system information.

In an embodiment of the present disclosure, identifying, by the base station, the one or more common beams from the beams according to the mapping between the beams and the RSs comprises: receiving, by the base station, a beam measurement on the beams according to the mapping between the beams and the RSs from the UE; and transmitting, by the base station, a first indication of the one or more common beams to the UE, wherein the first indication of the one or more common beams comprise a first selection of the one or more common beams by the base station according to the beam measurement.

In an embodiment of the present disclosure, identifying, by the base station, the one or more common beams from the beams according to the mapping between the beams and the RSs comprises: receiving, by the base station, UL RSs configured in the TCI states from the UE; performing, by the base station, a measurement on the UL RSs from the UE; and transmitting, by the base station, a second indication of the one or more common beams to the UE, wherein the second indication of the one or more common beams comprise a second selection of the one or more common beams by the base station according to the UL RSs.

In an embodiment of the present disclosure, the RS is the DL RS or the UL RS.

In a third aspect of the present disclosure, a user equipment (UE) of common beam determination comprises a memory, a transceiver, and a processor coupled to the memory and the transceiver. The processor is configured to: determine one or more transmission configuration indication (TCI) states from a base station, wherein the one or more TCI states comprises one or more reference signals (RSs) ; determine one or more beams from the base station, wherein the one or more beams are used for a multi-beam operation; identify one or more common beams from the one or more beams according to the one or more RSs; and use the one or more common beams for both a downlink (DL) reception and an uplink (UL) transmission in the multi-beam operation.

In an embodiment of the present disclosure, the processor is configured to perform the above method.

In a fourth aspect of the present disclosure, a base station of common beam determination comprises a memory, a transceiver, and a processor coupled to the memory and the transceiver. The processor is configured to: configure one or more transmission configuration indication (TCI) states to a user equipment (UE) , wherein the one or more TCI states comprises one or more reference signals (RSs) ; configure one or more beams to the UE, wherein the one or more beams are used for a multi-beam operation; identify one or more common beams from the one or more beams according to the one or more RSs; and use the one or more common beams for both a downlink (DL) transmission and an uplink (UL) reception in the multi-beam operation.

In a fifth aspect of the present disclosure, a non-transitory machine-readable storage medium has stored thereon instructions that, when executed by a computer, cause the computer to perform the above method.

In a sixth aspect of the present disclosure, a chip includes a processor, configured to call and run a computer program stored in a memory, to cause a device in which the chip is installed to execute the above method.

In a seventh aspect of the present disclosure, a computer readable storage medium, in which a computer program is stored, causes a computer to execute the above method.

In an eighth aspect of the present disclosure, a computer program product includes a computer program, and the computer program causes a computer to execute the above method.

In a ninth aspect of the present disclosure, a computer program causes a computer to execute the above method.

BRIEF DESCRIPTION OF DRAWINGS

In order to more clearly illustrate the embodiments of the present disclosure or related art, the following figures will be described in the embodiments are briefly introduced. It is obvious that the drawings are merely some embodiments of the present disclosure, a person having ordinary skill in this field can obtain other figures according to these figures without paying the premise.

FIG. 1 is a schematic diagram illustrating a beam indication in multi-beam transmission in multiple-input multiple-output (MIMO) .

FIG. 2 is a block diagram of one or more user equipments (UEs) and a base station (e.g., gNB) of communication in a communication network system according to an embodiment of the present disclosure.

FIG. 3 is a flowchart illustrating a method of common beam determination performed by a user equipment (UE) according to an embodiment of the present disclosure.

FIG. 4 is a flowchart illustrating a method of common beam determination performed by a base station according to an embodiment of the present disclosure.

FIG. 5 is a schematic diagram illustrating an example of common beam determination when a common beam is not present in a transmission configuration indication (TCI) state according to an embodiment of the present disclosure.

FIG. 6 is a schematic diagram illustrating an example of common beam determination when a common beam is not present in a TCI state according to an embodiment of the present disclosure.

FIG. 7 is a schematic diagram illustrating an example of common beam determination when a common beam is not present in a TCI state according to an embodiment of the present disclosure.

FIG. 8 is a block diagram of a system for wireless communication according to an embodiment of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure are described in detail with the technical matters, structural features, achieved objects, and effects with reference to the accompanying drawings as follows. Specifically, the terminologies in the embodiments of the present disclosure are merely for describing the purpose of the certain embodiment, but not to limit the disclosure.

Multi-beam Operation in Multiple-input multiple-output (MIMO) :

A target of beam management enhancement is mainly for latency and overhead reduction, a beam management may comprise three produces, i.e., a beam measurement, a beam report, and a beam indication. Firstly, it is expected that a base station such as a gNB sweeps multiple candidate beams for further management and transmits the candidate beams to a user equipment (UE) , and the UE measures the candidate beams based on some performance criteria. Then, after a beam measurement performed by the UE, the UE reports the beam measurement that the beams which satisfy the performance criteria to the gNB for further implementation. Finally, the gNB selects the best beam to indicate a transmission of a physical downlink shared channel (PDSCH) .

FIG. 1 illustrates a beam indication in multi-beam transmission in multiple-input multiple-output (MIMO) . FIG. 1 illustrates that, a beam link between a base station such as a gNB and a UE is established to enhance a beam indication. In a current technology such as Relase-15 new radio (NR) , a dynamic beam indication of PDSCH is designed to reduce latency and overhead, the dynamic beam indication is based on transmission configuration indication (TCI) states which associate with downlink reference signals (DL-RSs) , i.e., a synchronization signal block (SSB) and a channel state information-RS (CSI-RS) . The beam indication for PDSCH is dynamically triggered by a downlink control information (DCI) carrying on a physical downlink control channel (PDCCH) , and the UE applies an indicated beam and switches a receive (RX) beam after successfully decoding a DCI format. Further, in Relase-15, NR supports the beam indication for PDSCH transmission by using a 3-bit TCI field in a scheduling DCI, and the scheduling DCI can provide a spatial quasi co-location (QCL) relationship between a DL-RS and a demodulation reference signal (DM-RS) port of the PDSCH. Specifically, the gNB configures a TCI state pool which associates with multiple candidate beams via radio resource control (RRC) within a higher layer parameter such as PDSCH-Config. Then, the gNB activates candidate TCI states via media access control (MAC) control element (CE) signaling to map the candidate TCI states to codepoints of the DCI field. Finally, one TCI state for the DM-RS port of the PDSCH is indicated by the gNB via the DCI signaling.

FIG. 1 also illustrates that the UE can only apply the indicated beam after decoding the scheduling DCI and applying Rx beam switching. Thus, the UE needs to be given sufficient time to decode the PDCCH, and a time offset is needed, which is equal to or greater than a predefined threshold such as timeDurationForQCL, where the threshold is based on reported UE capability. Besides, in Relase-15/16, a higher layer parameter such as tci-PresentInDCI/tci- PresentInDCI-ForFormat1_2, is set as “enabled” for a CORESET scheduling the PDSCH. For DL beam indication, if the TCI field is present in the DCI, and the time offset between reception of the DL DCI and the corresponding PDSCH is equal to or greater than the predefined threshold such as timeDurationForQCL, the DM-RS of PDSCH is QCLed with the DL-RS in the indicated TCI state. Otherwise, it would be natural to use a predefined QCL assumption for PDSCH, i.e., default beam. When the TCI is present but the time offset between the reception of the DL DCI and the corresponding PDSCH is smaller than the predefined threshold such as timeDurationForQCL, the UE assumes that the QCL assumption of the lowest controlResourceSetId in the latest slot in which one or more CORESETs within an active bandwidth part (BWP) of a serving cell. The TCI field is not always present in DCI under some circumstances, if the TCI field is not present in DCI, the QCL assumption for the PDSCH follows the CORESET used for the PDCCH transmission.

In Relase-15, spatial relation information is configured by a higher layer parameter such as spatialRelationInfo for uplink (UL) beam indication, where the spatial relation information provides a RS according to which the UE forms a UL transmit (TX) beam for a target signal for which the spatial relation information is configured. For physical uplink control channel (PUCCH) and sounding reference signal (SRS) , spatial relation information can provide direct spatial assumption, while for physical uplink channel (PUSCH) , the UE indirectly derives the spatial relation information either from PUCCH (PUSCH scheduled with DCI format 0_0) or SRS resource (s) . In Relase-15/16, however, the DL and UL beam indication mechanisms are designed separately, some issues may exist such as latency and signaling overhead because two groups of RRC and MAC CE signaling are needed to configure and indicate beams for PDSCH and PUSCH.

In a current art, it is investigated that the PDSCH indication is scheduled by DCI format of PDCCH transmitted on the CORESET, while for the UL indication, SRS and PUCCH beam indications can be directly obtained by SpatialRelationInfo and PUCCH-SpatialRelationInfo, respectively. Different from SRS and PUCCH, the PUSCH beam is indicated through a scheduling request indicator (SRI) in DCI. In Relase-15/16, the DL and UL beams are indicated separately, which means that the gNB configures TCI and SpatialRelationInfo using different signalings. The unified TCI frame is introduced to eliminate a large signaling overhead. Furthermore, according to a future working item of Relase-17, beam restriction enhancement for simultaneous DL reception and UL transmission is enhanced because of a limitation on radio frequency (RF) analog beam steering component, and it is difficult for the UE to receive and transmit signals using different beams for different physical channels. Thus, in some embodiments of the present disclosure, it is beneficial to design the common beams for DL and UL beam indication.

As in Relase-15/16, a default beam is supported for PDCCH, PDSCH, PUCCH, PUSCH, and SRS, etc. When tci-PresentInDCI is absent or the scheduling offset is smaller than the threshold timeDurationForQCL, the default beam is TCI state or QCL assumption of the lowest controlResourceSetId in the latest slot monitored by the UE. When the UE is provided enableDefaultBeamPlForPUSCH0_0, enableDefaultBeamPlForSRS, or enableDefaultBeamPlForPUCCH, the default beam is the QCL assumption of CORESET with the lowest controlResourceSetId. One can see from above that multiple DL and UL channels can apply a single default beam indicated by the gNB to reduce the signaling overhead of beam indication. However, in Release-15/16, the designs of default beam are complicated and not implemented for all cases, because RSs for DL and UL default beam are not always aligned which may cause ambiguities on UE implementation of the common beam.

As mentioned above, to take the advantages of common beam, in some embodiments of the present disclosure, several methods are proposed to design a unified common beam design for DL and UL indication in multi-beam transmission. To solve the above issues for beam indication, some embodiments of the present disclosure propose methods regarding a unified TCI framework for DL and UL beam indication. Some embodiments of the present disclosure provide a unified common beam design for both DL reception and UL transmission in multi-beam operation. In this disclosure, several solutions are proposed to support the unified common beam indication design, which includes a joint common beam indication design scenario, a separate common beam indication design scenario, and a hybrid common beam indication design scenario. Further, a default common beam indication design scenario is also considered and proposed. The unified common beam design includes a common beam identification design and a common beam indication. For three scenarios, a mapping between configured beams and bit numbers or a mapping between the configured beams and slot of a received uplink signal by a base station such a gNB is designed to distinguish whether the configured beam is a common beam or not. Then, when the common beam in an indicated transmission configuration indication (TCI) is not present, the methods proposed to determine the common beams for different scenarios.

Beneficial effects of some embodiments of the present disclosure include at least one of the followings: 1. Define the unified common beam indication for both UL and DL in multi-beam transmission, and different common beam indication scenarios are considered. 2. Several common beam identification designs are proposed to distinguish whether the indicated mean is a common beam or not, and different common beam indication methods are proposed for different scenarios.

FIG. 2 illustrates that, in some embodiments, one or more user equipments (UEs) 10 and a base station (e.g., gNB) 20 for communication in a communication network system 30 according to an embodiment of the present disclosure are provided. The communication network system 30 is for example, a multiple-input multiple-output (MIMO) system. The communication network system 30 includes the one or more UEs 10 and the base station 20. The one or more UEs 10 may include a memory 12, a transceiver 13, and a processor 11 coupled to the memory 12, the transceiver 13. The base station 20 may include a memory 22, a transceiver 23, and a processor 21 coupled to the memory 22, the transceiver 23. The

processor

11 or 21 may be configured to implement proposed functions, procedures and/or methods described in this description. Layers of radio interface protocol may be implemented in the

processor

11 or 21. The

memory

12 or 22 is operatively coupled with the

processor

11 or 21 and stores a variety of information to operate the

processor

11 or 21. The

transceiver

13 or 23 is operatively coupled with the

processor

11 or 21, and the

transceiver

13 or 23 transmits and/or receives a radio signal.

The

processor

11 or 21 may include application-specific integrated circuit (ASIC) , other chipset, logic circuit and/or data processing device. The

memory

12 or 22 may include read-only memory (ROM) , random access memory (RAM) , flash memory, memory card, storage medium and/or other storage device. The

transceiver

13 or 23 may include baseband circuitry to process radio frequency signals. When the embodiments are implemented in software, the techniques described herein can be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The modules can be stored in the

memory

12 or 22 and executed by the

processor

11 or 21. The

memory

12 or 22 can be implemented within the

processor

11 or 21 or external to the

processor

11 or 21 in which case those can be communicatively coupled to the

processor

11 or 21 via various means as is known in the art.

In some embodiments, the processor 11 is configured to: determine one or more transmission configuration indication (TCI) states from the base station 20, wherein the one or more TCI states comprises one or more reference signals (RSs) ; determine one or more beams from the base station 20, wherein the one or more beams are used for a multi-beam operation; identify one or more common beams from the one or more beams according to the one or more RSs; and use the one or more common beams for both a downlink (DL) reception and an uplink (UL) transmission in the multi-beam operation. This can solve issues in the prior art, define a unified common beam indication for data and control transmission/reception for DL and UL in the multi-beam operation, enhance a common beam design for data and control transmission/reception for DL and UL in the multi-beam operation, provide a good communication performance, and/or provide high reliability.

In some embodiments, the processor 21 is configured to: configure one or more transmission configuration indication (TCI) states to the UE 10, wherein the one or more TCI states comprises one or more reference signals (RSs) ; configure one or more beams to the UE 10, wherein the one or more beams are used for a multi-beam operation; identify one or more common beams from the one or more beams according to the one or more RSs; and use the one or more common beams for both a downlink (DL) transmission and an uplink (UL) reception in the multi-beam operation. This can solve issues in the prior art, define a unified common beam indication for data and control transmission/reception for DL and UL in the multi-beam operation, enhance a common beam design for data and control transmission/reception for DL and UL in the multi-beam operation, provide a good communication performance, and/or provide high reliability.

FIG. 3 illustrates a method 200 of common beam determination performed by a user equipment (UE) according to an embodiment of the present disclosure. In some embodiments, the method 200 includes: a block 202, determining, by the UE, one or more transmission configuration indication (TCI) states from a base station, wherein the one or more TCI states comprises one or more reference signals (RSs) ; a block 204, determining, by the UE, one or more beams from the base station, wherein the one or more beams are used for a multi-beam operation; a block 206, identifying, by the UE, one or more common beams from the one or more beams according to the one or more RSs; and a block 208, using, by the UE, the one or more common beams for both a downlink (DL) reception and an uplink (UL) transmission in the multi-beam operation. This can solve issues in the prior art, define a unified common beam indication for data and control transmission/reception for DL and UL in the multi-beam operation, enhance a common beam design for data and control transmission/reception for DL and UL in the multi-beam operation, provide a good communication performance, and/or provide high reliability.

FIG. 4 illustrates a method 300 of common beam determination performed by a base station according to an embodiment of the present disclosure. In some embodiments, the method 300 includes: a block 302, configuring, by the base station, one or more transmission configuration indication (TCI) states to a user equipment (UE) , wherein the one or more TCI states comprises one or more reference signals (RSs) ; a block 304, configuring, by the base station, one or more beams to the UE, wherein the one or more beams are used for a multi-beam operation; a block 306, identifying, by the base station, one or more common beams from the one or more beams according to the one or more RSs; and a block 308, using, by the base station, the one or more common beams for both a downlink (DL) transmission and an uplink (UL) reception in the multi-beam operation. This can solve issues in the prior art, define a unified common beam indication for data and control transmission/reception for DL and UL in the multi-beam operation, enhance a common beam design for data and control transmission/reception for DL and UL in the multi-beam operation, provide a good communication performance, and/or provide high reliability.

In an embodiment of the present disclosure, the one or more common beams are indicated according to the one or more RSs associated to the one or more beams. In an embodiment of the present disclosure, there is only one TCI state configured by the base station. In an embodiment of the present disclosure, when there is only one RS in the one TCI state, the RS is related to the common beam for both the DL reception and/or the UL transmission in the multi-beam operation. In an embodiment of the present disclosure, the RS comprises a DL RS and/or a UL RS. In an embodiment of the present disclosure, the DL RS comprises a channel state information (CSI) RS. In an embodiment of the present disclosure, the UL RS comprises a sounding reference signal (SRS) . In an embodiment of the present disclosure, the common beam is indicated using a radio resource control (RRC) signaling and a media access control (MAC) control element (CE) singling. In an embodiment of the present disclosure, the one TCI state is activated by a MAC CE signaling, a downlink control information (DCI) field is applied to indicate a beam in the one TCL state. In an embodiment of the present disclosure, when the indicated beam in the one TCI state is not the common beam and if there is other common beam associated with the RSs in the TCI state, the UE uses the common beam with a lowest index in the TCI state for both the DL reception and the UL transmission in the multi-beam operation. In an embodiment of the present disclosure, when the UE is configured with the beams associated with the RSs in the TCI states, the method further comprises determining, by the UE, a mapping between the beams and the RSs.

In an embodiment of the present disclosure, identifying, by the UE, the one or more common beams from the one or more beams according to the one or more RSs comprises: identifying, by the UE, the one or more common beams from the beams according to the mapping between the beams and the RSs. In an embodiment of the present disclosure, the RSs comprise parameters, and the parameters comprise at least one of the followings: bit numbers; or slots of a UL signal received by the base station. In an embodiment of the present disclosure, determining, by the UE, the mapping between the beams and the RSs is through system information. In an embodiment of the present disclosure, identifying, by the UE, the one or more common beams from the beams according to the mapping between the beams and the RSs comprises: performing, by the UE, a beam measurement on the beams according to the mapping between the beams and the RSs; reporting, by the UE, the beam measurement to the base station; receiving, by the UE, a first indication of the one or more common beams from the base station, wherein the first indication of the one or more common beams comprise a first selection of the one or more common beams by the base station according to the beam measurement. In an embodiment of the present disclosure, identifying, by the UE, the one or more common beams from the beams according to the mapping between the beams and the RSs comprises: performing, by the UE, a UL beam sweeping; transmitting, by the UE, UL RSs configured in the TCI states to the base station; and receiving, by the UE, a second indication of the one or more common beams from the base station, wherein the second indication of the one or more common beams comprise a second selection of the one or more common beams by the base station according to the UL RSs.

In an embodiment of the present disclosure, the one or more common beams depend on an associated UL RS, where the UL RS is the most recently received signal at the base station. In an embodiment of the present disclosure, the TCI states are activated by a MAC CE signaling, a downlink control information (DCI) field is applied to indicate one or more beams in the one or more TCI states in a scheduling time. In an embodiment of the present disclosure, when the one or more indicated beams in the one or more TCI states in the scheduling time are not one or more common beams, the UE uses a latest indicated common beam before the scheduling time for both the DL reception and the UL transmission in the multi-beam operation. In an embodiment of the present disclosure, the method is performed in a joint common beam indication mode, a separate common beam indication mode, a hybrid common beam indication mode, or a default common beam indication mode. In an embodiment of the present disclosure, when the method is performed in the joint common beam indication mode, the UE uses the same common beam for both the DL reception and the UL transmission in the multi-beam operation. In an embodiment of the present disclosure, for the joint common beam indication mode, both the DL reception and the UL transmission are indicated by only one common beam, when there is only one RS in the single TCI state, the RS is related to the common beam for both the DL reception and the UL transmission. In an embodiment of the present disclosure, the RS is the DL RS or the UL RS.

In an embodiment of the present disclosure, for the joint common beam indication mode, combination of K beams associated with flags is used to identify the common beams, where K is greater than 1. In an embodiment of the present disclosure, if several beams of the K beams are common beams, a corresponding flag value of each of the several beams is used to determine the common beams. In an embodiment of the present disclosure, if the DL RS provides the common beam, the base station selects a beam associated with a bit number in a flag through a reported CSI from the UE, if the UL RS provides the common beam, the base station selects a beam associated with the bit number in the flag through a SRS from the UE, the selected beam depends on an associated uplink signal, where the uplink signal is the most recently received signal at the base station, comprising the report CSI or the SRS, and the combination of K beams associated with flags is used to identify whether the indicated beam is the common beam or not. In an embodiment of the present disclosure, for the joint common beam indication mode, each beam is for a time slot unit, the base station selects a beam through the most recently received signal comprising a report CSI or a SRS, each signal received by the base station corresponds to a slot, and a corresponding relationship between the slot and the beam is used to identify whether the selected beam is the common beam or not.

In an embodiment of the present disclosure, when the method is performed in the separate common beam indication mode, the UE separately applies an independent common beam for both the DL reception and the UL transmission in the multi-beam operation. In an embodiment of the present disclosure, the one or more RSs in M TCIs provide a quasi co-location (QCL) assumption for the DL reception, the one or more RSs in N TCIs provide a spatial filter for the UL transmission, and one or more candidate common beams for the DL reception and the UL transmission are included in the M TCIs and the N TCIs, respectively, where M is greater than or equal to 1, and N is greater than or equal to 1. In an embodiment of the present disclosure, for the DL reception or the UL transmission, when there is only one TCI state, the TCL state comprises only one RS to provide the QCL assumption for the DL reception or the spatial filter for the UL transmission, the beam associate with the RS is the common beam for the DL reception or the UL transmission in the multi-beam operation. In an embodiment of the present disclosure, when the RSs are associated with multiple K DL beams and L UL beams included in the TCI states, the RSs are configured to indicate whether K times L beam pairs comprise the one or more common beams or not.

In an embodiment of the present disclosure, when the method is performed in the separate common beam indication mode and when there is only one TCI state comprising only one RS to provide a reference for QCL or spatial filter, the beam associate with the RS is the common beam for the DL reception or the UL transmission. In an embodiment of the present disclosure, when the method is performed in the separate common beam indication mode and when the base station performs a beam sweeping, the UE makes a beam measurement, after measuring the beam, the UE transmits the UL RS to the base station in slot positions associated with the measured beam, and the base station measures the UL RS and selects a best UL beam to obtain a beam pair. In an embodiment of the present disclosure, when the method is performed in the separate common beam indication mode and when there is only one TCI state, both DL beams associated with DL RSs and UL beams associated with UL RSs are configured in the TCI state. In an embodiment of the present disclosure, when the method is performed in the separate common beam indication mode and when there is only one TCI state and if both an indicated DL beam and an indicated UL beam of an indicated beam pair are not DL common beam and UL common beam, the UE uses the common beam with a lowest beam pair index in the TCI state for both the DL reception and the UL transmission in the multi-beam operation. In an embodiment of the present disclosure, when the method is performed in the separate common beam indication mode and when there is only one TCI state and if an indicated beam pair is not the common beam, but an indicated DL beam or an indicated UL beam of the indicated beam pair is a DL common beam or a UL common beam, the UE uses the common beam with the lowest beam pair index in the TCI state for DL and UL indication, where the lowest beam pair comprises the DL or UL common beam related to the indicated common beam pair.

In an embodiment of the present disclosure, when the method is performed in the separate common beam indication mode, when the UE is configured with multiple TCI states, when the common beam is not present in an indicated TCI state, and if both an indicated DL beam and an indicated UL beam of an indicated beam pair are not a DL common beam and an UL common beam, the UE performs the DL reception and the UL transmission using the latest indicated common beam before a scheduling time. In an embodiment of the present disclosure, when the method is performed in the separate common beam indication mode, when the UE is configured with multiple TCI states, when the common beam is not present in an indicated TCI state, and if a DL beam or a UL beam of an indicated common beam pair is the common beam, the UE performs the DL reception and the UL transmission using the latest indicated common beam before a scheduling time, where the indicated common beam comprises the DL or UL common beam related to the indicated common beam pair in the scheduling time. In an embodiment of the present disclosure, when the method is performed in the hybrid common beam indication mode, the UE uses a first type of common beam and a second type of common beam, where the first type of common beam is configured for both the DL reception and the UL transmission in the multi-beam operation, and the second type of common beam is only configured for the DL reception or the UL transmission in the multi-beam operation.

In an embodiment of the present disclosure, the one or more RSs configured in the one or more TCLs provide the first type of common beam and the second type of common beam. In an embodiment of the present disclosure, when the RSs are associated with multiple K DL beams, L UL beams, S beams applied for both the DL reception and the UL transmission included in the TCI states, the RSs are configured to indicate whether K times L plus S beam pairs comprise the one or more common beams or not. In an embodiment of the present disclosure, the first type of common beam and the second type of common beam have different priorities. In an embodiment of the present disclosure, the priority of the first type of common beam is greater than the second type of common beam. In an embodiment of the present disclosure, when the common beam in the TCI state is not present, the first type of common beam and the second type of common beam who are configured with higher priority included in the TCI state which indicated in the latest scheduling time is considered to be the common beam. In an embodiment of the present disclosure, a time window is configured by the base station for the UE to distinguish whether the common beam or the common beam pair is valid or not. In an embodiment of the present disclosure, if there are not only the first type of common beams included within the window time, the UE uses the common beam with a lowest index in the TCI state for both the DL reception and the UL transmission in the multi-beam operation; and/or if there are only the second type of common beams included within the window time, the UE uses the common beam with a lowest beam pair index in the TCI state for both the DL reception and the UL transmission in the multi-beam operation.

In an embodiment of the present disclosure, when the method is performed in the hybrid common beam indication mode, K times L beam pairs are obtained by combination of K DL beams associated with multiple DL RSs and L UL beams associated with multiple UL RSs, and there are total K times L plus S beams/pairs that can be used for the DL reception and the UL transmission. In an embodiment of the present disclosure, when the method is performed in the hybrid common beam indication mode, if there is a selected beam with index from a first beam to a sth beam, the UE measures the beam with RSs to provide the common beam only for the DL reception or the UL transmission; and/or if there is a selected beam with index from a first beam pair to a K times Lth beam pair, the UE measures the beam with the RSs to provide the common beam for both the DL reception and the UL transmission. In an embodiment of the present disclosure, when the method is performed in the default common beam indication mode, the UE uses one or more default common beams as one or more common beams when DL and UL default beams are aligned. In an embodiment of the present disclosure, the one or more default common beams comprise the latest common beam with the lowest index which is included in one of scheduling times. The first beam refers to beam ₁ in the following embodiments and the sth beam refers to the beam _s in the following embodiments.

In some embodiments, the unified common beam design for DL and UL beam indication includes a joint common beam indication mode, a separate common beam indication mode, and a hybrid common beam indication mode. For the joint common beam indication mode, different DL and UL channels use the same common beam. For the separate common beam indication, separately apply independent common beam for DL and UL indication, e.g., one common beam for DL transmission. For the hybrid common beam indication, there are two types of common beam configured for DL and UL, i.e., one type of common beam is configured for both DL and UL, and the other type of common beam is only configured for DL or UL indication. Further, a default common beam indication mode is also considered and proposed. Regarding the unified common beam (s) design of DL and UL beam indication, the design is based on common beam identification design and common beam indication design. Further, in some embodiments of the present disclosure, beams are all related to RSs. One RS can indicate one beam, but one beam can be indicated by multiple RSs, and the indication of the beam by the RS is indicated by the TCI. In other words, source reference RSs in the TCI state (s) provide common beams for DL reception (such as PDSCH reception) , where the TCI is indicated by QCL.

Joint common beam indication for DL and UL:

For the joint common beam indication, both DL and UL transmissions are indicated by only one common beam. For the purpose of joint common beam indication, source RSs in TCI state (s) provide common beams for both PDSCH reception and PUSCH transmission. The beam indication directly refers to the associated source reference RS (s) , without loss of generality. Some embodiments assume that K (K>=1) beams are configured for multi-beam transmission. When there is only one source RS in the single TCI state, i.e., K=1, the source RS is related to the common beam for both DL and UL transmissions, where the source RS can be a DL RS (e.g., CSI_RS) or a UL RS (e.g., SRS) .

Common beam identification design:

In some embodiments, the gNB and the UE are configured with multiple beams associated with multiple RSs, i.e., K>1. In this scenario, some embodiments introduce a set flag= {flag ₁, flag ₂, ......, flag _K} to distinguish whether the indicated beam is a common beam or not. Specifically, some embodiments associate parameter flag _i in flag with the ith beam, it is further expressed as beam _i for the sake of simplicity, where i=1, 2, …, K. If beam _i is a common beam, some embodiments set flag _i=1, otherwise flag _i=0. As is shown in table 1, there are multiple candidate common beams, and beam ₂, beam ₃, and beam _K associated with flag ₂=1, flag ₃=1 and flag _K=1 are the candidate common beams.

Table 1:

beam index	flag
Beam ₁	flag ₁=0
Beam ₂	flag ₂=1
Beam ₃	flag ₃=1
……	……
Beam _K-1	flag _K-1 =0
Beam _K	flag _K=1

Advantages of some embodiments are that: Through the combination of K beams associated with the flag, the common beams can be easily identified. Without the definition of flag, the UE may be confused about the common beams with other beams.

Relationship between the beam index and a value of flag and a relationship between the beam index and a slot index (as illustrated in table 2) are informed to the UE through a system information. The UE would make a CSI measurement when receives a beam sweeping from the gNB, and then report measurement results to the gNB. According to the reported CSI measurement, gNB selects a beam associated with a bit number in flag. Since there are one or more UL RSs, i.e., SRS, is configured in the TCI state (s) , When the UE performs UL beam sweeping, the uplink signal which the gNB receives is SRS rather than the reported CSI measurement. The proposed designs can also be applied to a scenario, after measuring the received SRS from the UE, the gNB sends an SRS resource indicator (SRI) to indicate the indicated beam to the UE. The indicated beam depends on the associated uplink signal, where the uplink signal is the most recently received signal at the base station.

Besides, for the joint beam identification, some embodiments also present a design based on time-domain resource assignment field to distinguish whether the indicated beam is a common beam or not. Multiple source RSs included in the TCI state and multiple beams are associated with the multiple source RSs. Some embodiments also assume that there are K beams are configured for the multi-beam transmission. K slot positions are configured for DL and UL transmissions. Specifically, as shown in Table 2, some embodiments introduce a set slot = {slot ₁, slot ₂, ......, slot _K} , where each parameter in slot refers to a slot position assigned for the indicated beam.

Table 2:

beam index	slot index
Beam ₁	slot ₁
Beam ₂	slot ₂
Beam ₃	slot ₃
……	……
Beam _K-1	slot _K-1
Beam _K	slot _K

Similarly, for a design based on time-domain resource assignment field. When the gNB performs a beam sweeping, the UE makes a beam measurement and then reports to the gNB in the slot position associated with the measured beam. When the gNB receives the reported beam measurement (CSI measurement) in a slot position, the gNB selects the associated beam. For UL sweeping, the UE transmits a UL-RS to the gNB in the associated slot position to make beam measurement. And the indicated beam depends on the associated uplink signal, where the uplink signal is the most recently received signal at gNB.

Common beam indication design:

In Relase-15/16 NR, the UE is configured with multiple TCI states by the gNB through a high level parameter such as PDSCH-Config for multi-beam transmission. After activation of one or more of TCI states by MAC CE signaling, the DCI field is applied to indicate the beam for DL reception. When the UE is configured with one TCI state, only using RRC signaling and MAC CE singling can achieve beam indication. In other words, when one or more TCIs are activated, all the configured RSs are activated, that is, the beams provided are also all activated. When the UE is configured with multiple TCI states, more than one TCI state are activated, the DCI field carrying on PDCCH is applied to schedule DL reception. That is to say, the DCI signaling selects a state, and the UE uses the beam associated with the RSs configured with the selected TCI (the indicated TCI in some embodiments of this disclosure) in the scheduling DCI field.

If both the indicated DL beam and UL beam of the indicated beam pair are not DL common beam and UL common beam, the UE uses the common beam with the lowest beam pair index in the TCI state for DL and UL indication. As shown in Table 5, when the index of indicated beam pair is 2 which consists of DL Beam ₁ and UL beam ₂, both DL Beam ₁ and UL beam ₂ are not common beam for DL and UL beam indication, the beam pair with index L+1 is used as common beam.

If the indicated beam pair is not a common beam, but the indicated DL beam or UL beam of the indicated beam pair is a DL common beam or UL common beam, the UE uses the common beam with the lowest beam pair index in the TCI state for DL and UL indication, where the lowest beam pair includes the DL or UL common beam related to the indicated common beam pair. As shown in Table 5, when the index of indicated beam pair is 2L+2 which consists of DL Beam ₃ and UL beam ₂, DL Beam ₃ is a common beam for DL, the beam pair with index 2L+1 is used as common beam.

In some embodiments, when there is only one TCI state configured by the gNB. If the indicated beam is not a common beam, and if there is (are) other common beam (s) associated with reference RSs in the TCI state, the UE uses the common beam with the lowest index in the TCI for DL and UL indication. For example: it is also assumed that beam ₂, beam ₃, and beam _K are the common beams provided in the TCI. If the indicated beam in the beam index by the two schemes (table 1 and table 2) is beam ₄ (not common beam) , because all beams are provided by the RSs configured in the TCI, when the TCI is activated by MAC CE, all beams are activated. The common beam with the lowest index among the activated beams is selected, that is, beam ₂. However, the indicated beams in the TCI state of scheduling DCI is not always present, when there are multiple TCI states configured via RRC, there may be a problem that arises if the RSs in the TCI state do not provide any candidate common beam, i.e., any RS in the indicated TCI state is not associated with a candidate common beam. In this case, RRC reconfiguration would lead to signaling overhead. In some embodiments, when the common beam is not present in the indicated TCI state, the UE performs the DL reception and UL transmission using the latest indicated common beam before the scheduling time. For example, as shown in FIG. 5, the common beam is not present in the TCI of scheduling time n, the UE uses the common beam indicated in time n-2.

Separate common beam indication for DL and UL:

For the separate common beam indication, some embodiments assume that the source RS in M TCIs provides QCL assumption for DL transmission, while the source RS in N TCIs provides the spatial filter for UL transmit, where M>=1, and N>=1. The candidate common beam (s) for DL reception and UL transmission is (are) included in M TCIs and N TCIs, respectively.

Common beam identification design:

For DL reception or UL transmission, when there is only one TCI state (i.e., M=N=1) that includes only one source RS to provide a reference for QCL or spatial filter, the beam associate with the source RS is the common beam for the DL or UL transmission.

When now consider the case that multiple source reference signals are included in each TCI state, in this case, both the TCI state (s) for DL indication and TCI state (s) for UL indication have multiple source RSs (i.e., DL-RS and UL-RS) . Each DL (UL) beam directly refers to the associated DL (UL) source RS (s) . Some embodiments assume that the UE is configured with K DL beams and L UL beams. some embodiments introduce a set DLCommonbeamflag which includes K parameters, i.e., DLCommonbeamflag = {Dlflag ₁, Dl flag ₂, ......, Dlflag _K} to indicate whether the indicated DL beam associated with the reference RSs is the common beam or not, and the set ULCommonbeamflag which includes L parameters, i.e., ULCommonbeamflag = {Ulflag ₁, Ul flag ₂, ......, Ulflag _L} to indicate whether the indicated UL beam associated with the source RSs is the common beam or not. For DL (UL) transmission, when the beam with index DL Beam _i (UL Beam _i) is a candidate common beam, some embodiments have flag _i=1, otherwise, flag _i=0. As is shown in Table 3, the DL beam ₂, DL beam ₃, and DL beam _K are the candidate common beams for DL transmission, and UL beam ₁ and UL beam _L are the candidate beams for UL transmission. Note that K and L are not always the same.

Table 3:

DL beam index	DLCommonbeam flag	UL beam index	ULCommon beam flag
DL beam ₁	Dlflag ₁=0	UL beam ₁	Ulflag ₁ =1
DL beam ₂	Dlflag ₂=1	UL beam ₂	Ulflag ₂ =0
DL beam ₃	Dlflag ₃=1	UL beam ₃	Ulflag ₃ =0
……	……	……	……
DL beam _K-1	Dlflag _K-1 =0	UL beam _L-1	Ulflag _L-1=0
DL beam _K	Dlflag _K=1	UL beam _L	Ulflag _L=1

Through the combination of K DL beams associated with the multiple DL RSs and L UL beams associated with the multiple UL RSs, some embodiments can obtain total K×L beam pairs, six of which are the common beams. As is shown in Table 4, where the set commonbeampairflag= {pairflag ₁, pairflag2, ......, pairflag _KL} is introduced to indicate whether the beam pair is a common beam or not.

Table 4:

As shown in Table 4, commonbeampair flag is configured to indicate whether beam pair is a common beam or not. When the gNB performs beam sweeping, the UE makes the beam measurement, the UE selects a best beam and reports to gNB. Simultaneously, the UE performs UL beam sweeping, and gNB measures the received UL-RS from UE, and also selects a best beam. After both DL and UL sweeping, a beam pair associated with the beam pair index according to the most recently received CSI report and UL reference RS is indicated. The indicated beam pair is configured with commonbeampair flag. In Table 4, the beam pair with Pairflag _i=1, i= L+1, 2L, 2L+1, 3×L, (K-1) L+1, or K×L is indicated explicitly to be a common beam.

Besides, Table 5 illustrates the design based on time-domain resource assignment field for the separate common beam identification. There are multiple reference RSs associated with multiple K DL beams and L UL beams included in the TCI state (s) , and K×L slot positions are configured to indicate whether the beam pairs are the common beam or not. Specifically, some embodiments introduce the set slot = {slot ₁, slot ₂, ......, slot _KL} , where each parameter in slot refers to a slot position assigned for beam transmission and the beam indices are associated with the K×L parameters in slot. Some embodiments also assume that DL beam ₂, DL beam ₃, and DL beam _K associated with the DL reference RSs are the candidate common beams, and UL beam ₁ and UL beam _L associated with UL reference RSs are the candidate beams for UL transmission.

Table 5:

For the design based on time-domain resource assignment field, when the gNB performs beam sweeping, the UE makes the beam measurement, after measuring the beam, the UE transmits the UL reference RSs to gNB in the slot positions associated with the measured beam. The gNB measures the UL reference RSs and selects a best UL beams, and finally obtains a beam pair. For example, When the UE measures DL beam ₂ and reports to the gNB, then the UE transmits UL RSs to gNB from slot L+1 to slot 2×L for UL beam measurement. If the best UL beam is associated with slot L+1 or slot 2×L, the obtained beam pair is a common beam.

Common beam indication design:

Similar to the above embodiments, when the UE is configured with one TCI state, only using RRC signaling and MAC CE singling can achieve beam indication. When the UE is configured with multiple TCI states, more than one TCI state are activated. DL reception is indicated by the TCI in the scheduling DCI field.

The relationship between the beam pair index and the value of set commonbeampair flag and the relationship between beam pair index and the slot index can be informed to UE through system information. In some embodiments, when the UE is configured with multiple TCI states. After the activation of TCI states, the indicated TCI state is selected by the scheduling DCI field. However, due to the candidate common beams are provided by the reference RSs in multiple TCI states configured via RRC, the indicated beam in the TCI state of scheduling DCI is not always present, there may be a problem that arises if the reference RSs in the indicated TCI state do not provide common beam, i.e., any reference RS in the TCI state is not associated with a candidate common beam. In this case, RRC reconfiguration would lead to signaling overhead. In FIG. 6, when the indicated beam in scheduling time n is beam pair ₁ and there is not any candidate common beam present in the indicated TCI state, the common beam indicated in time n-1 is used as a common beam. Thus, when the common beam is not present in the indicated TCI state, if both the indicated DL beam and UL beam of the indicated beam pair are not DL common beam and UL common beam, the UE performs the DL reception and UL transmission using the latest indicated common beam before the scheduling time.

In some embodiments, when the reference RSs for DL transmission and the reference RSs for UL transmission are separately configured. DL-RSs are only associated with DL candidate common beam, while UL-RSs is only associated with UL candidate common beam. In this scenario, it may result in a problem that the indicated beam pair includes UL common beam or DL common beam, e.g., the beam pair with index 1 and the beam pair with L+2 in Table 5. As shown in FIG. 6, when the indicated beam in scheduling n is beam pair ₁ and there is not any candidate common beam present in the TCI state, the common beam indicated in slot n-2 is used as a common beam. Thus, in some embodiments, when the common beam is not present in the indicated TCI state, and the DL or UL beam of the indicated common beam pair is a common beam, the UE performs the DL reception and UL transmission using the latest indicated common beam before scheduling time n, where the indicated common beam includes the DL or UL common beam related to the indicated common beam pair in scheduling time n.

Hybrid common beam indication for DL and UL:

For the hybrid common beam indication, there are two types of common beam configured for DL and UL, i.e., one type of common beam is configured for both DL and UL, it is called Type1 for simplicity, and the other type of common beam is only configured for DL or UL, it is called Type2 for simplicity. That is to say, the RSs configured in TCIs to provide a common beam for DL reception, a common beam for UL transmission, and a common beam for both DL reception and UL transmission.

Common beam identification design:

Similar to the above embodiments, multiple RSs are configured in the TCI state (s) , and multiple beams directly refer to the associated RS (s) . The UE is configured with K DL beams and L UL beams, besides, some embodiments assume that there are S beams that can be applied for both DL reception and UL transmission, K _c of which are the common beams. Similar to Table 3 and Table 4, suppose DL beam ₂, DL beam ₃, and DL beam _K are the candidate common beams for DL reception, and UL beam ₁ and UL beam _L are the candidate beams for UL transmission. K×L beam pairs are obtained by the combination of K DL beams associated with the multiple DL RSs and L UL beams associated with the multiple UL RSs, and six of which are the common beams. Thus, in some embodiments, there are total K×L+S beams (pairs) that can be used for DL and UL transmission, K _c+6 of which are the common beams (beam pairs) .

As is shown in Table 6, the set flag= {flag ₁, flag2, ......, flag _KL+S} is introduced to indicate whether the beam or beam pair is a common beam or not. When the beam with index Beam _i (Beam pair _i) is a candidate common beam, some embodiments have flag _i=1, otherwise, flag _i=0. Suppose K _c=2, and beam ₁ and beam ₂ are the candidate common beams for DL and UL transmission.

Besides, some embodiments also present the designs based on the time-domain resource assignment field. Similarly, K×L+S slot positions are configured to distinguish whether the beams (beam pairs) are common beams or not. Specifically, we introduce the set slot = {slot ₁, slot ₂, ......, slot _KL+S} , where each parameter in slot refers to a slot position, and the beam indices are associated with the K×L parameters in slot.

Table 6:

beam (beam pair) index	flag	slot
Beam pair ₁	flag ₁=0	slot ₁
Beam pair ₂	flag ₂=0	slot ₂
……	…..	…..
Beam pair _KL	flag _KL=1	slot _K×L
Beam ₁	flag _KL+1=1	slot _K×L+1
Beam ₂	flag _KL+2=1	slot _K×L+1
Beam ₃	flag _KL+3=0	slot _K×L+1
…….	……	……
Beam _S	flag _KL+S=0	slot _K×L+S

For the hybrid common beam scenario, the two common beam identification designs based on the introduction of flag and time-domain resource assignment field are similar to the above embodiments. When the gNB performs beam sweeping, the UE makes the beam measurement and selects a best beam. If the selected beam with index from Beam ₁ to Beam _S, i.e., the UE measures the beam with the beam with the RSs, a common beam is provided only for DL or UL, the identification designs are similar to that of the above embodiments. If the selected beam with index from Beam pair ₁ to Beam pair _KL, i.e., the UE measures the beam with the RSs, a common beam is provided for both DL reception and UL transmission, the identification designs are similar to that of the above embodiments.

Common beam indication design:

Similar to the above embodiments, when the UE is configured with one TCI state, only using RRC signaling and MAC CE singling can achieve beam indication. When the UE is configured with multiple TCI states, more than one TCI state are activated, and the indicated beam associated with RS carrying on the scheduling DCI field is decoded by UE.

There may be two types of common beam that exist in the TCI states. Thus, it is necessary to prioritize the different types of common beam. To further reduce the latency and signaling overhead, type ₁ common beams are predefined to have high priority than type ₂ common beams. The relationship between the beam (beam pair) index and the value of commonbeampair flag, the relationship between beam (beam pair) index and the slot, and the priority levels of type ₁ and type ₂ common beams are informed to UE through system information.

The common beam in the TCI state is not always present, there may be a problem that arises if the RSs in the TCI state do not provide common beam, i.e., any RS in the activated TCI states is not associated with a candidate common beam. In this case, RRC reconfiguration would lead to signaling overhead. The two types of common beam that are configured with higher priority included in the TCI state which indicated in the latest scheduling time is considered to be a common beam. Since the type ₁ or type ₂ common beam does not always present at the same time interval, e.g., the latest type ₁ common beam may be received a long time ago, and thus cannot be considered as an applicable common beam. Thus, a time window Tw is configured by the gNB for the UE to distinguish whether a common beam or beam pair is valid or not in FIG. 7.

In scheduling time n, when the common beam is not present in the indicated TCI, the UE determines the common beam using latest type 1 indicated common beam before scheduling time n, if there is a type 1 common beam configured within the time window Tw, e.g., Beam ₂ in FIG. 7. If there are not only type 1 common beams included within the time window Tw, the UE uses the same solution which similar to that of the above embodiments. If there are only type 2 common beams included within the time window Tw, the UE uses the same solution which similar to that of the above embodiments.

Default common beam indication for DL and UL:

The default beam-based indication is generally used in Release-15/16. In Release-15/16, the default of DL reception is the QCL assumption of a monitored CORESET with the lowest index in the latest slot, while for default PUCCH/PUSCH Tx beam, the UE refers to the TCI state of a configured CORESET with the lowest index. Therefore, the DL and UL default beams are not always aligned. Besides, the reference RS resources for DL and UL default beams in Relase15/16 are DL RS, which lack of flexibility.

In some embodiments, for the default beam indication designs, due to the misalign between the DL and UL default beams proposed in Release-15/16, the default common beam can be used as a common beam only if the DL and UL default beams are aligned. Besides, consider the case that DL and UL default beams are aligned, according to the rules of default beam in Release-15/16, the default common beam is the indicated beam included in the TCI state which is indicated in the latest scheduling time. For example, in FIG. 5, the default common beam is beam1 indicated in time n-1, which is not a common beam, but if there does exist another common in scheduling time n, some embodiments can also obtain a default common beam, otherwise, the default common beam needs to be found before time n. Thus, in some embodiments, the default common beam is the latest common beam with the lowest index which is included in one of the scheduling times.

Commercial interests for some embodiments are as follows. 1. Solving issues in the prior art. 2. Enhancing a common beam design for data and control transmission/reception for downlink (DL) and uplink (UL) in multi-beam transmission. 3. Defining a unified common beam indication for both UL and DL in multi-beam transmission. 4. Different common beam indication scenarios are considered. 5. Several common beam identification designs are proposed to distinguish whether an indicated mean is a common beam or not. 6. Different common beam indication methods are proposed for different scenarios. 7. Providing a good communication performance. 8. Providing a high reliability. 9. Some embodiments of the present disclosure are used by 5G-NR chipset vendors, V2X communication system development vendors, automakers including cars, trains, trucks, buses, bicycles, moto-bikes, helmets, and etc., drones (unmanned aerial vehicles) , smartphone makers, communication devices for public safety use, AR/VR device maker for example gaming, conference/seminar, education purposes. Some embodiments of the present disclosure are a combination of “techniques/processes” that can be adopted in 3GPP specification to create an end product. Some embodiments of the present disclosure propose technical mechanisms.

FIG. 8 is a block diagram of an example system 700 for wireless communication according to an embodiment of the present disclosure. Embodiments described herein may be implemented into the system using any suitably configured hardware and/or software. FIG. 8 illustrates the system 700 including a radio frequency (RF) circuitry 710, a baseband circuitry 720, an application circuitry 730, a memory/storage 740, a display 750, a camera 760, a sensor 770, and an input/output (I/O) interface 780, coupled with each other at least as illustrated. The application circuitry 730 may include a circuitry such as, but not limited to, one or more single-core or multi-core processors. The processors may include any combination of general-purpose processors and dedicated processors, such as graphics processors, application processors. The processors may be coupled with the memory/storage and configured to execute instructions stored in the memory/storage to enable various applications and/or operating systems running on the system.

The baseband circuitry 720 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The processors may include a baseband processor. The baseband circuitry may handle various radio control functions that enables communication with one or more radio networks via the RF circuitry. The radio control functions may include, but are not limited to, signal modulation, encoding, decoding, radio frequency shifting, etc. In some embodiments, the baseband circuitry may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry may support communication with an evolved universal terrestrial radio access network (EUTRAN) and/or other wireless metropolitan area networks (WMAN) , a wireless local area network (WLAN) , a wireless personal area network (WPAN) . Embodiments in which the baseband circuitry is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry.

In various embodiments, the baseband circuitry 720 may include circuitry to operate with signals that are not strictly considered as being in a baseband frequency. For example, in some embodiments, baseband circuitry may include circuitry to operate with signals having an intermediate frequency, which is between a baseband frequency and a radio frequency. The RF circuitry 710 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. In various embodiments, the RF circuitry 710 may include circuitry to operate with signals that are not strictly considered as being in a radio frequency. For example, in some embodiments, RF circuitry may include circuitry to operate with signals having an intermediate frequency, which is between a baseband frequency and a radio frequency.

In various embodiments, the transmitter circuitry, control circuitry, or receiver circuitry discussed above with respect to the user equipment, eNB, or gNB may be embodied in whole or in part in one or more of the RF circuitry, the baseband circuitry, and/or the application circuitry. As used herein, “circuitry” may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC) , an electronic circuit, a processor (shared, dedicated, or group) , and/or a memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable hardware components that provide the described functionality. In some embodiments, the electronic device circuitry may be implemented in, or functions associated with the circuitry may be implemented by, one or more software or firmware modules. In some embodiments, some or all of the constituent components of the baseband circuitry, the application circuitry, and/or the memory/storage may be implemented together on a system on a chip (SOC) . The memory/storage 740 may be used to load and store data and/or instructions, for example, for system. The memory/storage for one embodiment may include any combination of suitable volatile memory, such as dynamic random access memory (DRAM) ) , and/or non-volatile memory, such as flash memory.

In various embodiments, the I/O interface 780 may include one or more user interfaces designed to enable user interaction with the system and/or peripheral component interfaces designed to enable peripheral component interaction with the system. User interfaces may include, but are not limited to a physical keyboard or keypad, a touchpad, a speaker, a microphone, etc. Peripheral component interfaces may include, but are not limited to, a non-volatile memory port, a universal serial bus (USB) port, an audio jack, and a power supply interface. In various embodiments, the sensor 770 may include one or more sensing devices to determine environmental conditions and/or location information related to the system. In some embodiments, the sensors may include, but are not limited to, a gyro sensor, an accelerometer, a proximity sensor, an ambient light sensor, and a positioning unit. The positioning unit may also be part of, or interact with, the baseband circuitry and/or RF circuitry to communicate with components of a positioning network, e.g., a global positioning system (GPS) satellite.

In various embodiments, the display 750 may include a display, such as a liquid crystal display and a touch screen display. In various embodiments, the system 700 may be a mobile computing device such as, but not limited to, a laptop computing device, a tablet computing device, a netbook, an ultrabook, a smartphone, a AR/VR glasses, etc. In various embodiments, system may have more or less components, and/or different architectures. Where appropriate, methods described herein may be implemented as a computer program. The computer program may be stored on a storage medium, such as a non-transitory storage medium.

A person having ordinary skill in the art understands that each of the units, algorithm, and steps described and disclosed in the embodiments of the present disclosure are realized using electronic hardware or combinations of software for computers and electronic hardware. Whether the functions run in hardware or software depends on the condition of application and design requirement for a technical plan. A person having ordinary skill in the art can use different ways to realize the function for each specific application while such realizations should not go beyond the scope of the present disclosure. It is understood by a person having ordinary skill in the art that he/she can refer to the working processes of the system, device, and unit in the above-mentioned embodiment since the working processes of the above-mentioned system, device, and unit are basically the same. For easy description and simplicity, these working processes will not be detailed.

It is understood that the disclosed system, device, and method in the embodiments of the present disclosure can be realized with other ways. The above-mentioned embodiments are exemplary only. The division of the units is merely based on logical functions while other divisions exist in realization. It is possible that a plurality of units or components are combined or integrated in another system. It is also possible that some characteristics are omitted or skipped. On the other hand, the displayed or discussed mutual coupling, direct coupling, or communicative coupling operate through some ports, devices, or units whether indirectly or communicatively by ways of electrical, mechanical, or other kinds of forms.

The units as separating components for explanation are or are not physically separated. The units for display are or are not physical units, that is, located in one place or distributed on a plurality of network units. Some or all of the units are used according to the purposes of the embodiments. Moreover, each of the functional units in each of the embodiments can be integrated in one processing unit, physically independent, or integrated in one processing unit with two or more than two units.

If the software function unit is realized and used and sold as a product, it can be stored in a readable storage medium in a computer. Based on this understanding, the technical plan proposed by the present disclosure can be essentially or partially realized as the form of a software product. Or, one part of the technical plan beneficial to the conventional technology can be realized as the form of a software product. The software product in the computer is stored in a storage medium, including a plurality of commands for a computational device (such as a personal computer, a server, or a network device) to run all or some of the steps disclosed by the embodiments of the present disclosure. The storage medium includes a USB disk, a mobile hard disk, a read-only memory (ROM) , a random access memory (RAM) , a floppy disk, or other kinds of media capable of storing program codes.

While the present disclosure has been described in connection with what is considered the most practical and preferred embodiments, it is understood that the present disclosure is not limited to the disclosed embodiments but is intended to cover various arrangements made without departing from the scope of the broadest interpretation of the appended claims.

Claims

A method of common beam determination performed by a user equipment (UE) , comprising:

determining, by the UE, one or more transmission configuration indication (TCI) states from a base station, wherein the one or more TCI states comprises one or more reference signals (RSs) ;

determining, by the UE, one or more beams from the base station, wherein the one or more beams are used for a multi-beam operation;

identifying, by the UE, one or more common beams from the one or more beams according to the one or more RSs; and

using, by the UE, the one or more common beams for both a downlink (DL) reception and an uplink (UL) transmission in the multi-beam operation.
The method of claim 1, wherein the one or more common beams are indicated according to the one or more RSs associated to the one or more beams.
The method of claim 1 or 2, wherein there is only one TCI state configured by the base station.
The method of claim 3, wherein when there is only one RS in the one TCI state, the RS is related to the common beam for both the DL reception and/or the UL transmission in the multi-beam operation.
The method of claim 4, wherein the RS comprises a DL RS and/or a UL RS.
The method of claim 5, wherein the DL RS comprises a channel state information (CSI) RS.
The method of claim 5, wherein the UL RS comprises a sounding reference signal (SRS) .
The method of any one of claims 3 to 7, wherein the common beam is indicated using a radio resource control (RRC) signaling and a media access control (MAC) control element (CE) singling.
The method of claim 3, wherein the one TCI state is activated by a MAC CE signaling, a downlink control information (DCI) field is applied to indicate a beam in the one TCL state.
The method of claim 9, wherein when the indicated beam in the one TCI state is not the common beam and if there is other common beam associated with the RSs in the TCI state, the UE uses the common beam with a lowest index in the TCI state for both the DL reception and the UL transmission in the multi-beam operation.
The method of claim 1 or 2, wherein when the UE is configured with the beams associated with the RSs in the TCI states, the method further comprises determining, by the UE, a mapping between the beams and the RSs.
The method of claim 11, wherein identifying, by the UE, the one or more common beams from the one or more beams according to the one or more RSs comprises:

identifying, by the UE, the one or more common beams from the beams according to the mapping between the beams and the RSs.
The method of claim 11 or 12, wherein the RSs comprise parameters, and the parameters comprise at least one of the followings:

bit numbers; or

slots of a UL signal received by the base station.
The method of any one of claims 11 to 13, wherein determining, by the UE, the mapping between the beams and the RSs is through system information.
The method of any one of claims 12 to 14, wherein identifying, by the UE, the one or more common beams from the beams according to the mapping between the beams and the RSs comprises:

performing, by the UE, a beam measurement on the beams according to the mapping between the beams and the RSs;

reporting, by the UE, the beam measurement to the base station;

receiving, by the UE, a first indication of the one or more common beams from the base station, wherein the first indication of the one or more common beams comprise a first selection of the one or more common beams by the base station according to the beam measurement.
The method of any one of claims 12 to 15, wherein identifying, by the UE, the one or more common beams from the beams according to the mapping between the beams and the RSs comprises:

performing, by the UE, a UL beam sweeping;

transmitting, by the UE, UL RSs configured in the TCI states to the base station; and

receiving, by the UE, a second indication of the one or more common beams from the base station, wherein the second indication of the one or more common beams comprise a second selection of the one or more common beams by the base station according to the UL RSs.
The method of claim 16, wherein the one or more common beams depend on an associated UL RS, where the UL RS is the most recently received signal at the base station.
The method of any one of claims 11 to 17, wherein the TCI states are activated by a MAC CE signaling, a downlink control information (DCI) field is applied to indicate one or more beams in the one or more TCI states in a scheduling time.
The method of claim 18, wherein when the one or more indicated beams in the one or more TCI states in the scheduling time are not one or more common beams, the UE uses a latest indicated common beam before the scheduling time for both the DL reception and the UL transmission in the multi-beam operation.
The method of any one of claims 1 to 19, wherein the method is performed in a joint common beam indication mode, a separate common beam indication mode, a hybrid common beam indication mode, or a default common beam indication mode.
The method of claim 20, wherein when the method is performed in the joint common beam indication mode, the UE uses the same common beam for both the DL reception and the UL transmission in the multi-beam operation.
The method of claim 20, wherein for the joint common beam indication mode, both the DL reception and the UL transmission are indicated by only one common beam, when there is only one RS in the single TCI state, the RS is related to the common beam for both the DL reception and the UL transmission.
The method of claim 22, wherein the RS is the DL RS or the UL RS.
The method of claim 20, wherein for the joint common beam indication mode, combination of K beams associated with flags is used to identify the common beams, where K is greater than 1.
The method of claim 24, wherein if several beams of the K beams are common beams, a corresponding flag value of each of the several beams is used to determine the common beams.
The method of claim 25, wherein if the DL RS provides the common beam, the base station selects a beam associated with a bit number in a flag through a reported CSI from the UE, if the UL RS provides the common beam, the base station selects a beam associated with the bit number in the flag through a SRS from the UE, the selected beam depends on an associated uplink signal received at the base station in the most recently received signal comprising the report CSI or the SRS, and the combination of K beams associated with flags is used to identify whether the indicated beam is the common beam or not.
The method of claim 20, wherein for the joint common beam indication mode, each beam is for a time slot unit, the base station selects a beam through the most recently received signal comprising a report CSI or a SRS, each signal received by the base station corresponds to a slot, and a corresponding relationship between the slot and the beam is used to identify whether the selected beam is the common beam or not.
The method of claim 20, wherein when the method is performed in the separate common beam indication mode, the UE separately applies an independent common beam for both the DL reception and the UL transmission in the multi-beam operation.
The method of claim 28, wherein the one or more RSs in M TCIs provide a quasi co-location (QCL) assumption for the DL reception, the one or more RSs in N TCIs provide a spatial filter for the UL transmission, and one or more candidate common beams for the DL reception and the UL transmission are included in the M TCIs and the N TCIs, respectively, where M is greater than or equal to 1, and N is greater than or equal to 1.
The method of claim 28 or 29, wherein for the DL reception or the UL transmission, when there is only one TCI state, the TCL state comprises only one RS to provide the QCL assumption for the DL reception or the spatial filter for the UL transmission, the beam associate with the RS is the common beam for the DL reception or the UL transmission in the multi-beam operation.
The method of claim 28 or 29, wherein when the RSs are associated with multiple K DL beams and L UL beams included in the TCI states, the RSs are configured to indicate whether K times L beam pairs comprise the one or more common beams or not.
The method of claim 20, wherein when the method is performed in the separate common beam indication mode and when there is only one TCI state comprising only one RS to provide a reference for QCL or spatial filter, the beam associate with the RS is the common beam for the DL reception or the UL transmission.
The method of claim 20, wherein when the method is performed in the separate common beam indication mode and when the base station performs a beam sweeping, the UE makes a beam measurement, after measuring the beam, the UE transmits the UL RS to the base station in slot positions associated with the measured beam, and the base station measures the UL RS and selects a best UL beam to obtain a beam pair.
The method of claim 20, wherein when the method is performed in the separate common beam indication mode and when there is only one TCI state, both DL beams associated with DL RSs and UL beams associated with UL RSs are configured in the TCI state.
The method of claim 20, wherein when the method is performed in the separate common beam indication mode and when there is only one TCI state and if both an indicated DL beam and an indicated UL beam of an indicated beam pair are not DL common beam and UL common beam, the UE uses the common beam with a lowest beam pair index in the TCI state for both the DL reception and the UL transmission in the multi-beam operation.
The method of claim 20, wherein when the method is performed in the separate common beam indication mode and when there is only one TCI state and if an indicated beam pair is not the common beam, but an indicated DL beam or an indicated UL beam of the indicated beam pair is a DL common beam or a UL common beam, the UE uses the common beam with the lowest beam pair index in the TCI state for DL and UL indication, where the lowest beam pair comprises the DL or UL common beam related to the indicated common beam pair.
The method of claim 20, wherein when the method is performed in the separate common beam indication mode, when the UE is configured with multiple TCI states, when the common beam is not present in an indicated TCI state, and if both an indicated DL beam and an indicated UL beam of an indicated beam pair are not a DL common beam and an UL common beam, the UE performs the DL reception and the UL transmission using the latest indicated common beam before a scheduling time.
The method of claim 20, wherein when the method is performed in the separate common beam indication mode, when the UE is configured with multiple TCI states, when the common beam is not present in an indicated TCI state, and if a DL beam or a UL beam of an indicated common beam pair is the common beam, the UE performs the DL reception and the UL transmission using the latest indicated common beam before a scheduling time, where the indicated common beam comprises the DL or UL common beam related to the indicated common beam pair in the scheduling time.
The method of claim 20, wherein when the method is performed in the hybrid common beam indication mode, the UE uses a first type of common beam and a second type of common beam, where the first type of common beam is configured for both the DL reception and the UL transmission in the multi-beam operation, and the second type of common beam is only configured for the DL reception or the UL transmission in the multi-beam operation.
The method of claim 39, wherein the one or more RSs configured in the one or more TCLs provide the first type of common beam and the second type of common beam.
The method of claim 39 or 40, wherein when the RSs are associated with multiple K DL beams, L UL beams, S beams applied for both the DL reception and the UL transmission included in the TCI states, the RSs are configured to indicate whether K times L plus S beam pairs comprise the one or more common beams or not.
The method of any one of claims 39 to 41, wherein the first type of common beam and the second type of common beam have different priorities.
The method of claim 42, wherein the priority of the first type of common beam is greater than the second type of common beam.
The method of claim 42, wherein when the common beam in the TCI state is not present, the first type of common beam and the second type of common beam who are configured with higher priority included in the TCI state which indicated in the latest scheduling time is considered to be the common beam.
The method of claim 42, wherein a time window is configured by the base station for the UE to distinguish whether the common beam or the common beam pair is valid or not.
The method of claim 42, wherein if there are not only the first type of common beams included within the window time, the UE uses the common beam with a lowest index in the TCI state for both the DL reception and the UL transmission in the multi-beam operation; and/or if there are only the second type of common beams included within the window time, the UE uses the common beam with a lowest beam pair index in the TCI state for both the DL reception and the UL transmission in the multi-beam operation.
The method of claim 20, wherein when the method is performed in the hybrid common beam indication mode, K times L beam pairs are obtained by combination of K DL beams associated with multiple DL RSs and L UL beams associated with multiple UL RSs, and there are total K times L plus S beams/pairs that can be used for the DL reception and the UL transmission.
The method of claim 20, wherein when the method is performed in the hybrid common beam indication mode, if there is a selected beam with index from a first beam to a sth beam, the UE measures the beam with RSs to provide the common beam only for the DL reception or the UL transmission; and/or if there is a selected beam with index from a first beam pair to a K times Lth beam pair, the UE measures the beam with the RSs to provide the common beam for both the DL reception and the UL transmission.
The method of claim 20, wherein when the method is performed in the default common beam indication mode, the UE uses one or more default common beams as one or more common beams when DL and UL default beams are aligned.
The method of claim 49, wherein the one or more default common beams comprise the latest common beam with the lowest index which is included in one of scheduling times.
A method of common beam determination performed by a base station, comprising:

configuring, by the base station, one or more transmission configuration indication (TCI) states to a user equipment (UE) , wherein the one or more TCI states comprises one or more reference signals (RSs) ;

configuring, by the base station, one or more beams to the UE, wherein the one or more beams are used for a multi-beam operation;

identifying, by the base station, one or more common beams from the one or more beams according to the one or more RSs; and

using, by the base station, the one or more common beams for both a downlink (DL) transmission and an uplink (UL) reception in the multi-beam operation.
The method of claim 51, wherein the one or more common beams are indicated according to the one or more RSs associated to the one or more beams.
The method of claim 51 or 52, wherein there is only one TCI state configured by the base station.
The method of claim 53, wherein when there is only one RS in the one TCI state, the RS is related to the common beam for both the DL transmission and/or the UL reception in the multi-beam operation.
The method of claim 54, wherein the RS comprises a DL RS and/or a UL RS.
The method of claim 55, wherein the DL RS comprises a channel state information (CSI) RS.
The method of claim 55, wherein the UL RS comprises a sounding reference signal (SRS) .
The method of any one of claims 53 to 57, wherein the common beam is indicated using a radio resource control (RRC) signaling and a media access control (MAC) control element (CE) singling.
The method of claim 53, wherein the one TCI state is activated by a MAC CE signaling, a downlink control information (DCI) field is applied to indicate a beam in the one TCL state.
The method of claim 59, wherein when the indicated beam in the one TCI state is not the common beam and if there is other common beam associated with the RSs in the TCI state, the UE uses the common beam with a lowest index in the TCI state for both DL reception and UL transmission in the multi-beam operation.
The method of claim 60, wherein when the method is performed in the joint common beam indication mode, the UE uses the same common beam for both the DL reception and the UL transmission in the multi-beam operation.
The method of claim 61, wherein identifying, by the base station, the one or more common beams from the one or more beams according to the one or more RSs comprises:

identifying, by the base station, the one or more common beams from the beams according to the mapping between the beams and the RSs.
The method of claim 61 or 62, wherein the RSs comprise parameters, and the parameters comprise at least one of the followings:

bit numbers; or

slots of a UL signal received by the base station.
The method of any one of claims 61 to 63, wherein determining, by the base station, the mapping between the beams and the RSs is through system information.
The method of any one of claims 62 to 64, wherein identifying, by the base station, the one or more common beams from the beams according to the mapping between the beams and the RSs comprises:

receiving, by the base station, a beam measurement on the beams according to the mapping between the beams and the RSs from the UE; and

transmitting, by the base station, a first indication of the one or more common beams to the UE, wherein the first indication of the one or more common beams comprise a first selection of the one or more common beams by the base station according to the beam measurement.
The method of any one of claims 62 to 65, wherein identifying, by the base station, the one or more common beams from the beams according to the mapping between the beams and the RSs comprises:

receiving, by the base station, UL RSs configured in the TCI states from the UE;

performing, by the base station, a measurement on the UL RSs from the UE; and

transmitting, by the base station, a second indication of the one or more common beams to the UE, wherein the second indication of the one or more common beams comprise a second selection of the one or more common beams by the base station according to the UL RSs.
The method of claim 66, wherein the one or more common beams depend on an associated UL RS, where the UL RS is the most recently received signal at the base station.
The method of any one of claims 71 to 77, wherein the TCI states are activated by a MAC CE signaling, a downlink control information (DCI) field is applied to indicate one or more beams in the one or more TCI states in a scheduling time.
The method of claim 68, wherein when the one or more indicated beams in the one or more TCI states in the scheduling time are not one or more common beams, the UE uses a latest indicated common beam before the scheduling time for both the DL reception and the UL transmission in the multi-beam operation.
The method of any one of claims 51 to 69, wherein the method is performed in a joint common beam indication mode, a separate common beam indication mode, a hybrid common beam indication mode, or a default common beam indication mode.
The method of claim 70, wherein when the method is performed in the joint common beam indication mode, the UE uses the same common beam for both the DL reception and the UL transmission in the multi-beam operation.
The method of claim 70, wherein for the joint common beam indication mode, both the DL reception and the UL transmission are indicated by only one common beam, when there is only one RS in the single TCI state, the RS is related to the common beam for both the DL reception and the UL transmission.
The method of claim 72, wherein the RS is the DL RS or the UL RS.
The method of claim 70, wherein for the joint common beam indication mode, combination of K beams associated with flags is used to identify the common beams, where K is greater than 1.
The method of claim 74, wherein if several beams of the K beams are common beams, a corresponding flag value of each of the several beams is used to determine the common beams.
The method of claim 75, wherein if the DL RS provides the common beam, the base station selects a beam associated with a bit number in a flag through a reported CSI from the UE, if the UL RS provides the common beam, the base station selects a beam associated with the bit number in the flag through a SRS from the UE, the selected beam depends on an associated uplink signal, where the uplink signal is the most recently received signal at the base station, comprising the report CSI or the SRS, and the combination of K beams associated with flags is used to identify whether the indicated beam is the common beam or not.
The method of claim 70, wherein for the joint common beam indication mode, each beam is for a time slot unit, the base station selects a beam through the most recently received signal comprising a report CSI or a SRS, each signal received by the base station corresponds to a slot, and a corresponding relationship between the slot and the beam is used to identify whether the selected beam is the common beam or not.
The method of claim 70, wherein when the method is performed in the separate common beam indication mode, the UE separately applies an independent common beam for both the DL reception and the UL transmission in the multi-beam operation.
The method of claim 78, wherein the one or more RSs in M TCIs provide a quasi co-location (QCL) assumption for the DL reception, the one or more RSs in N TCIs provide a spatial filter for the UL transmission, and one or more candidate common beams for the DL reception and the UL transmission are included in the M TCIs and the N TCIs, respectively, where M is greater than or equal to 1, and N is greater than or equal to 1.
The method of claim 78 or 79, wherein for the DL reception or the UL transmission, when there is only one TCI state, the TCL state comprises only one RS to provide the QCL assumption for the DL reception or the spatial filter for the UL transmission, the beam associate with the RS is the common beam for the DL reception or the UL transmission in the multi-beam operation.
The method of claim 78 or 79, wherein when the RSs are associated with multiple K DL beams and L UL beams included in the TCI states, the RSs are configured to indicate whether K times L beam pairs comprise the one or more common beams or not.
The method of claim 70, wherein when the method is performed in the separate common beam indication mode and when there is only one TCI state comprising only one RS to provide a reference for QCL or spatial filter, the beam associate with the RS is the common beam for the DL reception or the UL transmission.
The method of claim 70, wherein when the method is performed in the separate common beam indication mode and when the base station performs a beam sweeping, the UE makes a beam measurement, after measuring the beam, the UE transmits the UL RS to the base station in slot positions associated with the measured beam, and the base station measures the UL RS and selects a best UL beam to obtain a beam pair.
The method of claim 70, wherein when the method is performed in the separate common beam indication mode and when there is only one TCI state, both DL beams associated with DL RSs and UL beams associated with UL RSs are configured in the TCI state.
The method of claim 70, wherein when the method is performed in the separate common beam indication mode and when there is only one TCI state and if both an indicated DL beam and an indicated UL beam of an indicated beam pair are not DL common beam and UL common beam, the UE uses the common beam with a lowest beam pair index in the TCI state for both the DL reception and the UL transmission in the multi-beam operation.
The method of claim 70, wherein when the method is performed in the separate common beam indication mode and when there is only one TCI state and if an indicated beam pair is not the common beam, but an indicated DL beam or an indicated UL beam of the indicated beam pair is a DL common beam or a UL common beam, the UE uses the common beam with the lowest beam pair index in the TCI state for DL and UL indication, where the lowest beam pair comprises the DL or UL common beam related to the indicated common beam pair.
The method of claim 70, wherein when the method is performed in the separate common beam indication mode, when the UE is configured with multiple TCI states, when the common beam is not present in an indicated TCI state, and if both an indicated DL beam and an indicated UL beam of an indicated beam pair are not a DL common beam and an UL common beam, the UE performs the DL reception and the UL transmission using the latest indicated common beam before a scheduling time.
The method of claim 70, wherein when the method is performed in the separate common beam indication mode, when the UE is configured with multiple TCI states, when the common beam is not present in an indicated TCI state, and if a DL beam or a UL beam of an indicated common beam pair is the common beam, the UE performs the DL reception and the UL transmission using the latest indicated common beam before a scheduling time, where the indicated common beam comprises the DL or UL common beam related to the indicated common beam pair in the scheduling time.
The method of claim 70, wherein when the method is performed in the hybrid common beam indication mode, the UE uses a first type of common beam and a second type of common beam, where the first type of common beam is configured for both the DL reception and the UL transmission in the multi-beam operation, and the second type of common beam is only configured for the DL reception or the UL transmission in the multi-beam operation.
The method of claim 89, wherein the one or more RSs configured in the one or more TCLs provide the first type of common beam and the second type of common beam.
The method of claim 89 or 90, wherein when the RSs are associated with multiple K DL beams, L UL beams, S beams applied for both the DL reception and the UL transmission included in the TCI states, the RSs are configured to indicate whether K times L plus S beam pairs comprise the one or more common beams or not.
The method of any one of claims 89 to 91, wherein the first type of common beam and the second type of common beam have different priorities.
The method of claim 92, wherein the priority of the first type of common beam is greater than the second type of common beam.
The method of claim 92, wherein when the common beam in the TCI state is not present, the first type of common beam and the second type of common beam who are configured with higher priority included in the TCI state which indicated in the latest scheduling time is considered to be the common beam.
The method of claim 92, wherein a time window is configured by the base station for the UE to distinguish whether the common beam or the common beam pair is valid or not.
The method of claim 92, wherein if there are not only the first type of common beams included within the window time, the UE uses the common beam with a lowest index in the TCI state for both the DL reception and the UL transmission in the multi-beam operation; and/or if there are only the second type of common beams included within the window time, the UE uses the common beam with a lowest beam pair index in the TCI state for both the DL reception and the UL transmission in the multi-beam operation.
The method of claim 70, wherein when the method is performed in the hybrid common beam indication mode, K times L beam pairs are obtained by combination of K DL beams associated with multiple DL RSs and L UL beams associated with multiple UL RSs, and there are total K times L plus S beams/pairs that can be used for the DL reception and the UL transmission.
The method of claim 70, wherein when the method is performed in the hybrid common beam indication mode, if there is a selected beam with index from a first beam to a sth beam, the UE measures the beam with RSs to provide the common beam only for the DL reception or the UL transmission; and/or if there is a selected beam with index from a first beam pair to a K times Lth beam pair, the UE measures the beam with the RSs to provide the common beam for both the DL reception and the UL transmission.
The method of claim 70, wherein when the method is performed in the default common beam indication mode, the UE uses one or more default common beams as one or more common beams when DL and UL default beams are aligned.
The method of claim 99, wherein the one or more default common beams comprise the latest common beam with the lowest index which is included in one of scheduling times.
A user equipment (UE) of common beam determination, comprising:

a memory;

a transceiver; and

a processor coupled to the memory and the transceiver;

wherein the processor is configured to perform the method of any one of claims 1 to 50.
A base station of common beam determination, comprising:

a memory;

a transceiver; and

a processor coupled to the memory and the transceiver;

wherein the processor is configured to perform the method of any one of claims 51 to 100.
A non-transitory machine-readable storage medium having stored thereon instructions that, when executed by a computer, cause the computer to perform the method of any one of claims 1 to 100.
A chip, comprising:

a processor, configured to call and run a computer program stored in a memory, to cause a device in which the chip is installed to execute the method of any one of claims 1 to 100.
A computer readable storage medium, in which a computer program is stored, wherein the computer program causes a computer to execute the method of any one of claims 1 to 100.
A computer program product, comprising a computer program, wherein the computer program causes a computer to execute the method of any one of claims 1 to 100.
A computer program, wherein the computer program causes a computer to execute the method of any one of claims 1 to 100.