Measurement Gap Configuration for Multi-TRP Antenna Calibration

Abstract

The base station may perform online calibration of antenna elements at two or more transmit receive points (TRPs) based on measurements of one or more user equipments (UEs). The base station may send a request to perform antenna calibration measurements for two or more TRPs during a measurement gap for one or more UEs. The base station may coordinate the transmission of reference signals between two or more TRPs during the measurement gap. The base station may receive reports based on the antenna calibration measurements from one or more UEs. The base station may calibrate one or more antenna elements of two or more TRPs based on the antenna calibration measurements.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims priority to the following applications: U.S. Provisional Application No. 63 / 044,644, filed on Jun. 26, 2020, and entitled "MEASUREMENT GAP CONFIGURATION FOR MULTI - TRP ANTENNA CALIBRATION"; and U.S. Patent Application No. 17 / 332,572, filed on May 27, 2021, and entitled "MEASUREMENT GAP CONFIGURATION FOR MULTI - TRP ANTENNA CALIBRATION", which are assigned to the assignee of the present application and are incorporated herein by reference in their entireties. Technical Field

[0003] Broadly speaking, the present disclosure relates to communication systems, and more particularly, to online antenna calibration using configured measurement gaps for multiple transmit - receive points (TRPs). Background Art

[0004] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasting. A typical wireless communication system may employ multiple access technologies that are capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single - carrier frequency division multiple access (SC - FDMA) systems, and time - division synchronous code division multiple access (TD - SCDMA) systems.

[0005] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at the urban, national, regional, and even global levels. An example telecommunication standard is 5G New Radio (NR). 5G NR is part of the continuous evolution of mobile broadband released by the Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., with the Internet of Things (IoT)), and other requirements. 5G NR includes services associated with enhanced mobile broadband (eMBB), massive machine - type communication (mMTC), and ultra - reliable low - latency communication (URLLC). Some aspects of 5G NR may be based on the 4G Long - Term Evolution (LTE) standard. There is a need for further improvement in 5G NR technology. These improvements may also be applicable to other multiple access technologies and telecommunication standards that employ these technologies. Summary of the Invention

[0006] A brief overview of one or more aspects is given below to provide a basic understanding of such aspects. This overview is not an extensive review of all the intended aspects and is neither intended to identify key or important elements of all aspects nor to delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that follows.

[0007] In one aspect, the present disclosure provides a method for wireless communication for a base station to perform online antenna calibration. The method may include: sending a request for performing antenna calibration measurements for two or more transmit receive points (TRPs) during a measurement gap for one or more user equipments (UEs). The method may include: coordinating the transmission of reference signals between the two or more TRPs during the measurement gap. The method may include: receiving, from the one or more UEs, a report based on the antenna calibration measurements. The method may include: calibrating one or more antenna elements of the two or more TRPs based on the antenna calibration measurements.

[0008] In some implementations, the method may further include: selecting the one or more UEs based on at least one of: the capabilities of the one or more UEs, the power or thermal overhead of the one or more UEs, the data rate requirements of the one or more UEs, or the reliability requirements of the one or more UEs.

[0009] In some implementations, the request configures the measurement gap for performing the antenna calibration measurements. The number and period of the measurement gaps may be based on at least one of: the number of panels at the two or more TRPs, the antenna array geometry and size of the panels at the two or more TRPs, the maximum transmit power level at the two or more TRPs, the existing antenna calibration inaccuracies at the two or more TRPs, the number of layers from each TRP, the array gain required in the downlink at the UE or in the uplink at the two or more TRPs, or the steering angle of the beams in the beamformed transmissions at the two or more TRPs. The number and period of the measurement gaps may be based on the thermal overhead associated with each TRP.

[0010] In some implementations, the method further includes: transmitting the received report to another TRP among the two or more TRPs via a backhaul network.

[0011] In some implementations, the request includes a joint quasi co-location (QCL) mapping for receiving transmissions from the TRPs to the one or more UEs.

[0012] In some implementations, the report includes measurements using a fixed receive beam for transmissions from at least one of the two or more TRPs and a different receive beam for transmissions from at least another one of the two or more TRPs.

[0013] In some implementations, coordinating the transmission of the reference signal during the measurement gap between the two or more TRPs includes performing multi-user multiple-input multiple-output (MU-MIMO) transmission to multiple UEs.

[0014] The present disclosure also provides: an apparatus (e.g., a base station) including a memory storing computer-executable instructions and at least one processor configured to execute the computer-executable instructions to perform the above method; an apparatus including units for performing the above method; and a non-transitory computer-readable medium storing computer-executable instructions for performing the above method.

[0015] In one aspect, the present disclosure provides a method for UE-assisted online antenna calibration for wireless communication for two or more TRPs. The method may include: receiving a request to perform antenna calibration measurements during a measurement gap for two or more TRPs. The method may include: performing the antenna calibration measurements on reference signals from the two or more TRPs during the measurement gap. The method may include: sending a report to at least one of the TRPs based on the antenna calibration measurements.

[0016] In some implementations, performing the antenna calibration measurements includes: performing measurements using a fixed receive beam for transmissions from at least one of the two or more TRPs and a different receive beam for transmissions from at least another one of the two or more TRPs.

[0017] In some implementations, the request includes a joint QCL mapping for receiving transmissions from the two or more TRPs to the UE.

[0018] In some implementations, performing the antenna calibration measurements includes: performing measurements of MU-MIMO transmissions using different receive beams to measure the effects of sidelobes or beam nulls.

[0019] The present disclosure also provides: a device (e.g., a UE) including a memory storing computer-executable instructions and at least one processor configured to execute the computer-executable instructions to perform the above method; a device including units for performing the above method; and a non-transitory computer-readable medium storing computer-executable instructions for performing the above method.

[0020] In one aspect, the present disclosure provides a method for wireless communication for a UE to perform online antenna calibration. The method may include: sending a request for the UE to send a reference signal to two or more transmit-receive points (TRPs) during a measurement gap for antenna calibration measurement. The method may include: sending the reference signal to the two or more TRPs during the measurement gap. The method may include: receiving a report based on the antenna calibration measurement from the two or more TRPs. The method may include: calibrating one or more antenna elements of the UE based on the antenna calibration measurement.

[0021] In some implementations, the TRP configures the measurement gap in response to the request.

[0022] The present disclosure also provides: a device (e.g., a UE) including a memory storing computer-executable instructions and at least one processor configured to execute the computer-executable instructions to perform the above method; a device including units for performing the above method; and a non-transitory computer-readable medium storing computer-executable instructions for performing the above method.

[0023] To achieve the foregoing and related purposes, one or more aspects include the features described in detail hereinafter and particularly pointed out in the claims. The following description and the drawings set forth certain illustrative features of one or more aspects in detail. However, these features are only indicative of some of the various ways in which the principles of the various aspects may be employed, and this specification is intended to include all such aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic diagram showing an example of a wireless communication system and an access network according to certain aspects of the present description.

[0025] Figure 2A is a schematic diagram showing an example of a first frame according to certain aspects of the present description.

[0026] Figure 2B is a schematic diagram showing an example of a DL channel within a subframe according to certain aspects of the present description.

[0027] Figure 2C A schematic diagram showing an example of a second frame according to certain aspects of the present description.

[0028] Figure 2D A schematic diagram showing an example of a subframe according to certain aspects of the present description.

[0029] Figure 3 A schematic diagram showing an example of a base station and a user equipment (UE) in an access network according to certain aspects of the present description.

[0030] Figure 4 A schematic diagram showing an example of a downlink transmission with multiple transmit-receive points (TRPs) according to certain aspects of the present description.

[0031] Figure 5 A schematic diagram showing an example of a reference signal measurement in a downlink transmission with multiple TRPs according to certain aspects of the present description.

[0032] Figure 6 A schematic diagram showing an example of measurements performed by multiple UEs in a downlink transmission with multiple TRPs according to certain aspects of the present description.

[0033] Figure 7 A schematic diagram showing an example of communication and processes between an example base station and a UE according to certain aspects of the present description.

[0034] Figure 8 A conceptual data flow diagram showing the data flow between different units / components in an example base station according to certain aspects of the present description.

[0035] Figure 9 A conceptual data flow diagram showing the data flow between different units / components in an example UE according to certain aspects of the present description.

[0036] Figure 10 A flowchart showing an example of a method for wireless communication for base station antenna calibration according to certain aspects of the present description.

[0037] Figure 11 A flowchart showing an example of a method for wireless communication for UE-assisted antenna calibration according to certain aspects of the present description.

[0038] Figure 12 A flowchart showing an example of a method for wireless communication for UE antenna calibration according to certain aspects of the present description. Detailed Description

[0039] The detailed description set forth below in connection with the accompanying drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. For the purpose of providing a thorough understanding of the various concepts, the detailed description includes specific details. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

[0040] For millimeter wave communications, beamforming can be used to coherently combine energy and overcome the high path loss observed at higher frequencies. Beamforming weights for signaling can be computed. For example, beamforming weights can be computed when applied at a UE antenna in receive (Rx) mode. Since the RF paths / circuits are different (e.g., different sets of amplifiers, mixers, couplers, filters, etc. in Tx and Rx modes), the same weights cannot be reused for transmission from the UE antenna. This mismatch can be compensated for by a procedure called antenna calibration. Precise phase and amplitude calibration at the antenna elements is a function of temperature and carrier frequency. As more antenna elements are used, the cost of achieving calibration increases. Typically, low-complexity calibration is an offline / one-time exercise where there is a specific error between the true and recorded phase and amplitude. In many cases, the error can be large (e.g., 10° - 25° in phase). Thus, improved techniques for antenna calibration may be beneficial.

[0041] In one aspect, the present disclosure provides techniques for network-assisted calibration of antennas in a multi-TRP beamforming scenario. For example, when a TRP is used for communication, the TRP can perform online calibration of the antenna elements of one or more TRPs based on measurements performed by one or more UEs communicating with the TRP. For example, one or more base stations can send requests for one or more UEs to perform antenna calibration measurements during measurement gaps. The base stations can select UEs based on UE capabilities and the impact on UE performance. During the measurement gaps, one or more base stations can coordinate the transmission of reference signals between two or more TRPs. One or more UEs can perform antenna calibration measurements using different receive beams. One or more UEs can send reports based on the antenna calibration measurements. The base stations can calibrate one or more antenna elements of two or more TRPs based on the antenna calibration measurements. The base stations can convey the reports via a backhaul network to another base station or TRP.

[0042] In some wireless communication systems, a measurement gap can be provided as the duration for which a UE pauses signal transmission to a serving cell (PCell) in order to measure neighboring cells (inter-frequency or inter-RAT). For example, in NR, both per-UE measurement gaps and per-frequency range (FR) measurement gaps can be configured. Different measurement gap mode configurations (e.g., measurement gap length and measurement gap repetition period) can be used. Such measurement gaps can be used to measure the beams of neighboring cells for cell / beam handover, adding another component carrier in carrier aggregation, etc. The measurement gaps can be used to measure appropriate synchronization signal blocks (SSBs) instead of monitoring all SSBs (saving power). In some systems, higher layer parameters can define the SSB measurement timing configuration (SMTC) window. Although such configuration options allow the UE to determine the relative signal strength of cells and select beams, further coordination may be required for network-assisted calibration measurements in a multi-TRP scenario. In particular, the existing configurations may be provided at a period that may not be sufficient to achieve good beamforming performance, and thus improved network-assisted calibration opportunities may be desirable.

[0043] Certain aspects of a telecommunications system will now be presented with reference to various devices and methods. These devices and methods will be described in the following detailed description by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as "elements") and illustrated in the accompanying drawings. These elements can be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

[0044] By way of example, an element, or any portion of an element, or any combination of elements can be implemented as a "processing system" including one or more processors. Examples of processors include a microprocessor, a microcontroller, a graphics processing unit (GPU), a central processing unit (CPU), an application processor, a digital signal processor (DSP), a reduced instruction set computing (RISC) processor, a system on a chip (SoC), a baseband processor, a field programmable gate array (FPGA), a programmable logic device (PLD), a state machine, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functions described throughout the present disclosure. One or more processors in the processing system can execute software. Whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise, software should be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software components, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, processes, functions, etc.

[0045] Accordingly, in one or more example embodiments, the described functionality may be implemented in hardware, software, or any combination thereof. If implemented in software, the functionality may be stored or encoded on a computer-readable medium as one or more instructions or code. Computer-readable media includes computer storage media. Computer-readable media may be referred to as non-transitory computer-readable media. Non-transitory computer-readable media may exclude transitory signals. Storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media may include random access memory (RAM), read only memory (ROM), electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of the aforementioned types of computer-readable media, or any other medium capable of storing computer-executable code in the form of instructions or data structures that can be accessed by a computer.

[0046] Figure 1 is a schematic diagram showing an example of a wireless communication system and an access network 100. The wireless communication system (also referred to as a wireless wide area network (WWAN)) includes a base station 102, a UE 104, an evolved packet core (EPC) 160, and another core network 190 (e.g., a 5G core (5GC)). The base station 102 may include macro cells (high-power cellular base stations) and / or small cells (low-power cellular base stations). Macro cells include base stations. Small cells include femto cells, pico cells, and micro cells.

[0047] In one aspect, as shown, one or more of the base stations 102 may include an antenna calibration component 120 that configures a UE to perform antenna calibration measurements and perform antenna calibration based on the antenna calibration measurements. The antenna calibration component 120 may include a request component 122 configured to send a request for one or more UEs 104 to perform antenna calibration measurements for two or more TRPs during a measurement gap. The antenna calibration component 120 may include a coordination component 124 configured to coordinate the transmission of reference signals between two or more TRPs during a measurement gap. The antenna calibration component 120 may include a reporting component 126 configured to receive reports from one or more UEs based on the antenna calibration measurements. The antenna calibration component 120 may include a calibration component 128 configured to calibrate one or more antenna elements of two or more TRPs based on the antenna calibration measurements.

[0048] In one aspect, as shown in the figure, one or more of the UEs 104 in the UE 104 may include an antenna calibration assistance component 140 that generates an antenna calibration measurement report that can be used by two or more TRPs to calibrate antenna elements. The calibration assistance component 140 may include a request component 142 configured to receive a request for two or more TRPs to perform antenna calibration measurements during a measurement gap. The calibration assistance component 140 may include a measurement component 144 configured to perform antenna calibration measurements on reference signals from two or more TRPs during a measurement gap. The calibration assistance component 140 may include a reporting component 146 configured to send a report to at least one of the TRPs based on the antenna calibration measurements. In some implementations, one or more of the UEs 104 in the UE 104 may include an antenna calibration component 120 for performing antenna calibration with the help of two or more TRPs.

[0049] Base stations 102 configured for 4G LTE (collectively, evolved universal mobile telecommunications system (UMTS) terrestrial radio access network (E-UTRAN)) may be connected to the EPC 160 via a first backhaul link 132 (e.g., S1 interface), which may be wired or wireless. Base stations 102 configured for 5G NR (collectively, next-generation RAN (NG-RAN)) may be connected to the core network 190 via a second backhaul link 184, which may be wired or wireless. Among other functions, the base stations 102 may perform one or more of the following functions: transmission of user data, wireless channel encryption and decryption, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection establishment and release, load balancing, distribution of non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), user and device tracking, radio access network information management (RIM), paging, positioning, and delivery of warning messages. The base stations 102 may communicate with each other directly or indirectly (e.g., via the EPC 160 or the core network 190) via a third backhaul link 134 (e.g., X2 interface). The third backhaul link 134 may be wired or wireless.

[0050] Base station 102 can communicate wirelessly with UE 104. Each base station in base station 102 can provide communication coverage for a corresponding geographical coverage area 110. There can be overlapping geographical coverage areas 110. For example, small cell 102' can have a coverage area 110' that overlaps with the coverage areas 110 of one or more macro base stations 102. A network including both small cells and macro cells can be referred to as a heterogeneous network. The heterogeneous network can also include a Home evolved Node B (eNB) (HeNB), which can provide services to a restricted group called a Closed Subscriber Group (CSG). The communication link 112 between base station 102 and UE 104 can include an uplink (UL) (also referred to as a reverse link) transmission from UE 104 to base station 102 and / or a downlink (DL) (also referred to as a forward link) transmission from base station 102 to UE 104. The communication link 112 can use multiple-input multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and / or transmit diversity. The communication link can be over one or more carriers. Base station 102 / UE 104 can use a spectrum with a bandwidth of up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz) per carrier, allocated in carrier aggregation with a total of up to Yx MHz (x component carriers) for transmission in each direction. The carriers can be adjacent to each other or can be non-adjacent to each other. The allocation of carriers can be asymmetric with respect to DL and UL (e.g., more or fewer carriers can be allocated for DL compared to UL). The component carriers can include a primary component carrier and one or more secondary component carriers. The primary component carrier can be referred to as the Primary Cell (PCell), and the secondary component carriers can be referred to as Secondary Cells (SCells).

[0051] Some UEs 104 can communicate with each other using device-to-device (D2D) communication links 158. The D2D communication links 158 can use DL / UL WWAN spectrum. The D2D communication links 158 can use one or more sidelink channels, such as the Physical Sidelink Broadcast Channel (PSBCH), Physical Sidelink Discovery Channel (PSDCH), Physical Sidelink Shared Channel (PSSCH), and Physical Sidelink Control Channel (PSCCH). D2D communication can be through various wireless D2D communication systems such as, for example, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

[0052] The wireless communication system may further include a Wi-Fi access point (AP) 150 that communicates with a Wi-Fi station (STA) 152 via a communication link 154 in the 5 GHz unlicensed spectrum. When communicating in the unlicensed spectrum, the STA 152 / AP 150 may perform a clear channel assessment (CCA) before communication to determine whether the channel is available.

[0053] The small cell 102' may operate in licensed and / or unlicensed spectrum. When operating in the unlicensed spectrum, the small cell 102' may adopt NR and use the same 5 GHz unlicensed spectrum as that used by the Wi-Fi AP 150. The small cell 102' adopting NR in the unlicensed spectrum may enhance the coverage of the access network and / or increase the capacity of the access network.

[0054] The base station 102 (whether it is a small cell 102' or a large cell (e.g., a macro base station)) may include an eNB, a next-generation node B (gNodeB, gNB) or other types of base stations. Some base stations (such as the gNB 180) may operate in one or more frequency bands within the electromagnetic spectrum.

[0055] The electromagnetic spectrum is generally subdivided into various categories, frequency bands, channels, etc. based on frequency / wavelength. In 5G NR, two initial operating frequency bands have been identified as the frequency range name FR1 (410 MHz - 7.125 GHz) and FR2 (24.25 GHz - 52.6 GHz). The frequencies between FR1 and FR2 are often referred to as mid-band frequencies. Although a part of FR1 is larger than 6 GHz, FR1 is often (interchangeably) referred to as the "sub-6 GHz" band in various documents and articles. Similar naming issues sometimes occur with FR2, which is often (interchangeably) referred to as the "millimeter wave" (mmW) band in documents and articles, although it is different from the extremely high frequency (EHF) band (30 GHz - 300 GHz) identified as the "millimeter wave" band by the International Telecommunication Union (ITU).

[0056] In view of the above aspects, unless otherwise explicitly stated, it should be understood that if used herein, terms such as "sub-6 GHz" may broadly represent frequencies that may be below 6 GHz, may be within FR1, or may include mid-band frequencies. Further, unless otherwise explicitly stated, it should be understood that if used herein, terms such as "millimeter wave" may broadly represent frequencies that may include mid-band frequencies, may be within FR2, or may be within the EHF band. Communication using mmW radio frequency bandwidth has extremely high path loss and short distance. The mmW base station 180 may utilize beamforming 182 with the UE 104 to compensate for path loss and short distance.

[0057] The EPC 160 may include a Mobility Management Entity (MME) 162, other MMEs 164, a Serving Gateway 166, a Multimedia Broadcast Multicast Service (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC) 170, and a Packet Data Network (PDN) Gateway 172. The MME 162 may communicate with a Home Subscriber Server (HSS) 174. The MME 162 is a control node that processes signaling between the UE 104 and the EPC 160. Generally, the MME 162 provides bearer and connection management. All user Internet Protocol (IP) packets are transported through the Serving Gateway 166, which itself is connected to the PDN Gateway 172. The PDN Gateway 172 provides IP address allocation to the UE and other functions. The PDN Gateway 172 and the BM-SC 170 are connected to an IP service 176. The IP service 176 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), a PS streaming service, and / or other IP services. The BM-SC 170 may provide functions for MBMS user service provision and delivery. The BM-SC 170 may serve as an entry point for MBMS transmissions for content providers, may be used to authorize and initiate MBMS bearer services within a Public Land Mobile Network (PLMN), and may be used to schedule MBMS transmissions. The MBMS Gateway 168 may be used to distribute MBMS services to base stations 102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area for a particular service being broadcast, and may be responsible for session management (start / stop) and collecting charging information related to eMBMS.

[0058] The core network 190 may include an Access and Mobility Management Function (AMF) 192, other AMFs 193, a Session Management Function (SMF) 194, and a User Plane Function (UPF) 195. The AMF 192 may communicate with a Unified Data Management (UDM) 196. The AMF 192 is a control node that processes signaling between the UE 104 and the core network 190. Generally, the AMF 192 provides QoS flow and session management. All user Internet Protocol (IP) packets are transmitted through the UPF 195. The UPF 195 provides UE IP address allocation and other functions. The UPF 195 is connected to an IP service 197. The IP service 197 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), a PS streaming service, and / or other IP services.

[0059] A base station may include and / or be referred to as a gNB, Node B, eNB, access point, base station transceiver, radio base station, radio transceiver, transceiver function, basic service set (BSS), extended service set (ESS), transmission and reception point (TRP), or some other suitable term. Base station 102 provides an access point to EPC 160 or core network 190 for UE 104. Examples of UE 104 include cellular phones, smart phones, session initiation protocol (SIP) phones, laptop computers, personal digital assistants (PDAs), satellite radio units, global positioning systems, multimedia devices, video devices, digital audio players (e.g., MP3 players), cameras, game consoles, tablet devices, smart devices, wearable devices, vehicles, electricity meters, gas pumps, large or small kitchen appliances, healthcare devices, implants, sensors / actuators, displays, or any other device with similar functionality. Some of the UEs 104 in UE104 may be referred to as IoT devices (e.g., parking meters, gas pumps, ovens, vehicles, heart monitors, etc.). UE 104 may also be referred to as a station, mobile station, user station, mobile unit, user unit, radio unit, remote unit, mobile device, radio device, wireless communication device, remote device, mobile user station, access terminal, mobile terminal, wireless terminal, remote terminal, handheld device, user agent, mobile client, client, or some other suitable term.

[0060] Although the following description may focus on 5G NR, the concepts described herein may be applicable to other similar areas, such as LTE, LTE-A, CDMA, GSM, or other wireless technologies including future 6G technologies.

[0061] Figure 2A FIG. 200 is a schematic diagram showing an example of a first subframe within a 5G NR frame structure. Figure 2B FIG. 230 is a schematic diagram showing an example of a DL channel within a 5GNR subframe. Figure 2C FIG. 250 is a schematic diagram showing an example of a second subframe within a 5G NR frame structure. Figure 2D FIG. 280 is a schematic diagram showing an example of a UL channel within a 5G NR subframe. The 5G NR frame structure may be FDD (wherein, for a specific set of subcarriers (carrier system bandwidth), the subframes within the set of subcarriers are dedicated to DL or UL), or it may be TDD (wherein, for a specific set of subcarriers (carrier system bandwidth), the subframes within the set of subcarriers are dedicated to both DL and UL). In passing Figure 2A 、 2CIn the provided example, the 5G NR frame structure is assumed to be TDD, where subframe 4 is configured with slot format 28 (with most being DL), where D is DL, U is UL, and X can be flexibly used between DL / UL, and subframe 3 is configured with slot format 34 (with most being UL). Although subframes 3 and 4 are shown as having slot formats 34 and 28 respectively, any particular subframe can be configured with any of the various available slot formats 0 - 61. Slot formats 0 and 1 are full DL and full UL respectively. The other slot formats 2 - 61 include a mixture of DL, UL, and flexible symbols. The UE is configured with a slot format by the received Slot Format Indicator (SFI) (configured dynamically by Downlink Control Information (DCI) or semi-statically / statically by Radio Resource Control (RRC) signaling). Note that the following description also applies to the 5G NR frame structure as TDD.

[0062] Other wireless communication technologies may have different frame structures and / or different channels. A frame (10 ms) can be divided into 10 equally sized subframes (1 ms). Each subframe may include one or more slots. A subframe may also include mini-slots, and a mini-slot may include 7, 4, or 2 symbols. Depending on the slot configuration, each slot may include 7 or 14 symbols. For slot configuration 0, each slot may include 14 symbols, and for slot configuration 1, each slot may include 7 symbols. Symbols on the DL may be Cyclic Prefix (CP) OFDM (CP - OFDM) symbols. Symbols on the UL may be CP - OFDM symbols (for high throughput scenarios) or Discrete Fourier Transform (DFT) spread OFDM (DFT - s - OFDM) symbols (also known as Single Carrier Frequency Division Multiple Access (SC - FDMA) symbols) (for power - limited scenarios; limited to single - stream transmission). The number of slots within a subframe is based on the slot configuration and numerology. For slot configuration 0, different numerologies μ0 to 5 allow 1, 2, 4, 8, 16, and 32 slots per subframe respectively. For slot configuration 1, different numerologies 0 to 2 allow 2, 4, and 8 slots per subframe respectively. Accordingly, for slot configuration 0 and numerology μ, there are 14 symbols / slot and 2 μ slots / subframe. The subcarrier spacing and symbol length / duration are functions of the numerology. The subcarrier spacing can be equal to 2 μ *15 kHz, where μ is numerology 0 to 5. Thus, numerology μ = 0 has a subcarrier spacing of 15 kHz, and numerology μ = 5 has a subcarrier spacing of 480 kHz. The symbol length / duration is inversely related to the subcarrier spacing. Figure 2A - 2DProvide an example of time slot configuration 0 (with 14 symbols per time slot) and digital scheme μ = 2 (with 4 time slots per subframe). The time slot duration is 0.25 ms, the subcarrier spacing is 60 kHz, and the symbol duration is approximately 16.67 μs.

[0063] A resource grid can be used to represent the frame structure. Each time slot includes resource blocks (RBs) (also referred to as physical RBs (PRBs)), where a PRB spans 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.

[0064] As shown in Figure 2A Some of the REs in the RE carry reference (pilot) signals (RSs) for the UE. The RS can include demodulation RSs (DM-RSs) for channel estimation at the UE (indicated as R x , where 100x is the port number, but other DM-RS configurations are possible) and channel state information reference signals (CSI-RSs). The RS can also include beam measurement RSs (BRSs), beam refinement RSs (BRRSs), and phase tracking RSs (PT-RSs).

[0065] Figure 2B Show an example of various DL channels within a subframe of a frame. The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs), where each CCE includes nine RE groups (REGs), and each REG includes 4 consecutive REs in an OFDM symbol. The primary synchronization signal (PSS) can be in symbol 2 of a specific subframe of the frame. The PSS is used by the UE104 to determine subframe / symbol timing and the physical layer identity. The secondary synchronization signal (SSS) can be in symbol 4 of a specific subframe of the frame. The SSS is used by the UE to determine the physical layer cell identity group number and the radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE can determine the physical cell identifier (PCI). Based on the PCI, the UE can determine the position of the above-mentioned DM-RS. The physical broadcast channel (PBCH) carrying the master information block (MIB) can be logically grouped with the PSS and SSS to form a synchronization signal (SS) / PBCH block. The MIB provides the number of RBs in the system bandwidth and the system frame number (SFN). The physical downlink shared channel (PDSCH) carries user data, broadcast system information not sent by the PBCH (such as system information blocks (SIBs)), and paging messages.

[0066] As shown in Figure 2CAs shown, some of the REs in RE carry DM-RS for channel estimation at the base station (indicated as R for a specific configuration, but other DM-RS configurations are possible). The UE can send DM-RS for the physical uplink control channel (PUCCH) and DM-RS for the physical uplink shared channel (PUSCH). The PUSCH DM-RS can be sent in the one or two symbols preceding the PUSCH. The PUCCH DM-RS can be sent with different configurations according to whether a short PUCCH or a long PUCCH is sent and according to the specific PUCCH format used. The UE can send a sounding reference signal (SRS). The SRS can be sent in the last symbol of the subframe. The SRS can have a comb structure, and the UE can send the SRS on one of the combs in the comb. The SRS can be used by the base station for channel quality estimation to enable frequency-dependent scheduling on the UL.

[0067] Figure 2D An example of various UL channels within a subframe of a frame is shown. The PUCCH can be located as indicated in one configuration. The PUCCH carries uplink control information (UCI), such as a scheduling request, a channel quality indicator (CQI), a precoding matrix indicator (PMI), a rank indicator (RI), and HARQ ACK / NACK feedback. The PUSCH carries data and can additionally be used to carry a buffer status report (BSR), a power headroom report (PHR), and / or UCI.

[0068] Figure 3It is a block diagram of the communication between the base station 310 and the UE 350 in the access network. In the DL, IP packets from the EPC 160 can be provided to the controller / processor 375. The controller / processor 375 implements layer 3 and layer 2 functions. Layer 3 includes the radio resource control (RRC) layer, and layer 2 includes the service data adaptation protocol (SDAP) layer, the packet data convergence protocol (PDCP) layer, the radio link control (RLC) layer, and the media access control (MAC) layer. The controller / processor 375 provides: RRC layer functions associated with: broadcasting of system information (e.g., MIB, SIB), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter-radio access technology (RAT) mobility, and measurement configuration for UE measurement reporting; PDCP layer functions associated with: header compression / decompression, security (encryption, decryption, integrity protection, integrity verification), and handover support functions; RLC layer functions associated with: transmission of upper layer packet data units (PDUs), error correction via ARQ, concatenation, segmentation, and reassembly of RLC service data units (SDUs), re-segmentation of RLC data PDUs, and re-ordering of RLC data PDUs; and MAC layer functions associated with: mapping between logical channels and transport channels, multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction via HARQ, priority handling, and logical channel prioritization.

[0069] The transmit (TX) processor 316 and the receive (RX) processor 370 implement the layer 1 functions associated with various signal processing functions. Layer 1, which includes the physical (PHY) layer, may include error detection on the transport channel, forward error correction (FEC) encoding / decoding on the transport channel, interleaving, rate matching, mapping to the physical channel, modulation / demodulation of the physical channel, and MIMO antenna processing. The TX processor 316 processes the mapping to the signal constellation based on various modulation schemes (e.g., binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), M-phase shift keying (M-PSK), M-order quadrature amplitude modulation (M-QAM)). The encoded and modulated symbols can then be divided into parallel streams. Each stream can then be mapped to OFDM subcarriers, multiplexed with reference signals (e.g., pilots) in the time and / or frequency domain, and then combined using the inverse fast Fourier transform (IFFT) to generate a physical channel carrying a stream of time-domain OFDM symbols. The OFDM stream is space precoded to generate multiple spatial streams. The channel estimate from the channel estimator 374 can be used to determine the encoding and modulation schemes and for spatial processing. The channel estimate can be derived based on the reference signals transmitted by the UE 350 and / or channel status feedback. Each spatial stream can then be provided to a different antenna 320 via a separate transmitter 318TX. Each transmitter 318TX can modulate the RF carrier with the corresponding spatial stream for transmission.

[0070] At the UE 350, each receiver 354RX receives the signal via its corresponding antenna 352. Each receiver 354RX recovers the information modulated onto the RF carrier and provides the information to the receive (RX) processor 356. The TX processor 368 and the RX processor 356 implement the layer 1 functions associated with various signal processing functions. The RX processor 356 can perform spatial processing on the information to recover any spatial streams destined for the UE 350. If multiple spatial streams are destined for the UE 350, they can be combined by the RX processor 356 into a single OFDM symbol stream. The RX processor 356 then uses the fast Fourier transform (FFT) to convert the OFDM symbol stream from the time domain to the frequency domain. The frequency-domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols and reference signals on each subcarrier are recovered and demodulated by determining the most likely signal constellation points transmitted by the base station 310. These soft decisions can be based on the channel estimate calculated by the channel estimator 358. The soft decisions are then decoded and deinterleaved to recover the data and control signals originally transmitted by the base station 310 on the physical channel. The data and control signals are then provided to the controller / processor 359, which implements the layer 3 and layer 2 functions.

[0071] The controller / processor 359 may be associated with a memory 360 that stores program code and data. The memory 360 may be referred to as a computer-readable medium. In the UL, the controller / processor 359 provides demultiplexing, packet reassembly, decryption, header decompression, and control signal processing between the transport channel and the logical channel to recover IP packets from the EPC 160. The controller / processor 359 is also responsible for error detection using the ACK and / or NACK protocols to support HARQ operations.

[0072] Similar to the functions described in connection with DL transmissions performed by the base station 310, the controller / processor 359 provides: RRC layer functions associated with: system information (e.g., MIB, SIB) acquisition, RRC connection, and measurement reporting; PDCP layer functions associated with: header compression / decompression and security (encryption, decryption, integrity protection, integrity verification); RLC layer functions associated with: transfer of upper layer PDUs, error correction via ARQ, concatenation, segmentation, and reassembly of RLC SDUs, re-segmentation of RLC data PDUs, and re-ordering of RLC data PDUs; and MAC layer functions associated with: mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction via HARQ, priority handling, and logical channel prioritization.

[0073] Channel estimates derived by the channel estimator 358 based on reference signals or feedback sent by the base station 310 may be used by the TX processor 368 to select an appropriate modulation and coding scheme and to facilitate spatial processing. The spatial streams generated by the TX processor 368 may be provided to different antennas 352 via a separate transmitter 354TX. Each transmitter 354TX may modulate an RF carrier using a respective spatial stream for transmission.

[0074] UL transmissions are processed at the base station 310 in a manner similar to that described in connection with the receiver functions at the UE 350. Each receiver 318RX receives signals via its respective antenna 320. Each receiver 318RX recovers the information modulated onto the RF carrier and provides the information to the RX processor 370.

[0075] The controller / processor 375 can be associated with a memory 376 that stores program code and data. The memory 376 can be referred to as a computer-readable medium. In the UL, the controller / processor 375 provides demultiplexing, packet reassembly, decryption, header decompression, control signal processing between the transport channel and the logical channel to recover IP packets from the UE 350. The IP packets from the controller / processor 375 can be provided to the EPC 160. The controller / processor 375 is also responsible for error detection using the ACK and / or NACK protocols to support HARQ operations.

[0076] At least one of the TX processor 368, RX processor 356, and controller / processor 359 can be configured to perform aspects of the antenna calibration assist component 140 in connection with Figure 1 In addition, in some implementations, the UE 350 can include an antenna calibration component 120, and at least one of the TX processor 358, RX processor 356, and controller / processor 359 can be configured to perform aspects of the antenna calibration component 120 in connection with Figure 1 the antenna calibration component 120.

[0077] At least one of the TX processor 316, RX processor 370, and controller / processor 375 can be configured to perform aspects of the antenna calibration component 120 in connection with Figure 1 In addition, in some implementations, the base station 310 can include an antenna calibration assist component 140, and at least one of the TX processor 310, RX processor 370, and controller / processor 375 can be configured to perform aspects associated with Figure 1 the antenna calibration assist component 140.

[0078] Figure 4It is a schematic diagram showing an example of downlink transmission with multiple TRPs. For example, the first base station 402 can be associated with the first TRP (TRP1) 412, and the second base station 404 can be associated with the second TRP (TRP2) 414. Each TRP can transmit its respective beam 422, 424. The beams 422, 424 can be the result of different antenna configurations at the base stations 402, 404 or the TRPs 412, 414, which can generally include large antenna arrays for beam control. In one aspect, the channel can include multiple paths 432, 434 (e.g., paths 432a–432c and 434a–434c) between the TRPs 412, 414 and the UE 104. For example, if there is a line of sight between one of the TRPs 412 and 414 and the UE 104, there can be direct paths 432a, 434a. RF signals can also travel along indirect paths. For example, the signal may be reflected from an object such as a building, a vehicle, or a window. From the perspective of the UE 104, the signal may appear to come from clusters 442, 444. The clusters (e.g., clusters 442, 444) can be sources of reflection or diffraction of the signals arriving at the UE 104. For example, cluster 442a can correspond to TRP 414, and cluster 444a can correspond to TRP2 414. Clusters 442b, 442c, 444b, and 444c can correspond to the objects that reflect the signals in the indirect paths 432b, 432c, 434b, and 434c, respectively.

[0079] The UE 104 can have an active antenna configuration that generates receive beams 450, 452. The UE 104 can control the antenna weights to direct the receive beams 450 and 452 towards one or more of the clusters 442, 444. The strongest cluster can be referred to as the dominant cluster, and the other clusters can be referred to as the sub-dominant clusters. The UE 104 can dynamically change the active antenna configuration to focus on one or more of the clusters. For example, when cluster 442a is the dominant cluster, the UE 104 can use the active antenna configuration that generates the receive beam 450. When it is cluster 444a, the UE 104 can change the active antenna configuration to generate the receive beam 452.

[0080] In one aspect, the base station may determine joint beamforming for transmissions from TRP1 and TRP2 to a single UE 104 based on joint quasi - co - location (QCL) mapping. For example, UE 104 may experience poor channel conditions, and joint beamforming may provide a strong enough signal to achieve a desired data rate. However, due to calibration errors / inaccuracies at TRP1 and TRP2, precise / high - gain beamforming to UE 104 may not be possible. For example, some of these errors may be time - varying and may not be estimable via an offline process. According to the present disclosure, TRP1 and TRP2 may collaboratively activate a network - assisted antenna calibration process. For UE - assisted TRP calibration, at least two TRPs may request one or more UEs to assist the TRPs by making measurements during measurement gaps and reporting the measurements to the at least two TRPs.

[0081] Multiple parameters may be configured for network - assisted antenna calibration. Generally, more measurements at any UE result in greater power consumption and thermal overhead, which do not contribute to transmitting UE data. Thus, the measurements may be associated with lower performance (e.g., lower data rate, higher error probability, or higher latency). The TRP may coordinate the use of measurement gaps among multiple UEs in the network. The UEs selected to assist the TRP may depend on the capabilities of each UE (e.g., assistance capabilities, which may be determined by an independent bit field), thermal / power overhead, rate / reliability requirements, etc.

[0082] Each TRP may configure multiple measurement gaps for the UE for antenna calibration, and the period of the measurement gaps may be determined by the capabilities of each TRP. Example capabilities of a TRP include: the number of panels, the antenna array geometry and size of the panels, the maximum transmit power level, existing antenna calibration inaccuracies, the number of layers from the TRP, the array gain required in the downlink at the UE or in the uplink at the TRP, or the steering angle of the beam in the beamformed transmission at the TRP. For example, a larger array may consume more resources for measurements. A larger maximum transmit power level may provide greater gain and consume more resources. Existing antenna calibration inaccuracies may require more measurement resources. A larger number of layers from the TRP may require more resources. More required array gain may require more resources. For the steering angle, the closer the steering angle is to the boresight of the antenna array, more resources may be required for refinement. Additionally, while power consumption is generally not a primary consideration for a base station, thermal overhead may impose a limit. Thus, more resources may be provided by a TRP with lower thermal overhead (which may not require good calibration) and transferred via the backhaul to a TRP that requires better calibration (e.g., due to higher thermal overhead).

[0083] Figure 5FIG. 500 is a schematic diagram showing an example measurement of reference signals in a downlink transmission with multiple TRPs. The TRPs can be calibrated using joint quasi-co-location (QCL) mapping. For example, the TRPs can select beams 522, 524 based on joint QCL mapping. The TRPs can jointly transmit QCL-based reference signals from both TRP1 412 and TRP2 414 during a measurement gap, such that the UE 104 can perform measurements. For example, beam 522 can be reflected from vehicle 542, and beam 524 can be reflected from building 544. When the UE 104 attempts to measure or identify potential sidelobes with different Rx beams 550 (e.g., beams 550a, 550b, 550c, and 550d) received from TRP1, the UE 104 can fix the Rx beam 552 received from TRP2 414. The UE 104 can report measurements (e.g., phase and amplitude) associated with each of the different Rx beams 550.

[0084] Figure 6 FIG. 600 is a schematic diagram showing example measurements performed by multiple UEs 660, 662 in a downlink transmission with multiple TRPs 612, 614. For example, the multiple TRPs 612, 614 can be provided by a single base station 602. The TRPs can utilize QCL mapping signaled jointly from two TRPs, such that all UEs 660, 662 can perform measurements during a measurement gap. The TRPs 612, 614 can perform MU-MIMO for multiple UEs 660, 662. For example, TRP1 612 can generate beam 622, and TRP2 614 can generate beam 624. Beam 622 can be reflected from vehicle 642 to reach UE2 662. Beam 624 can be reflected from building 644 to reach UE1 660. Each UE 660, 662 can attempt different Rx beams 650, 652 to measure the impact of sidelobes from other TRPs. It may not be necessary to limit the Rx beams of some UEs to be fixed. For example, UE1 660 can attempt Rx beams 650a, 650b, 650c to detect sidelobe 626, and UE2 can attempt beams 652a, 652b, and 652c to detect sidelobe 628.

[0085] Figure 7 FIG. 700 is a schematic diagram showing an example communication and process of example TRPs 412, 414 and UE 104. The TRPs 412 and 414 can be provided by separate base stations 402, 404 as Figure 5 shown, or can be provided by a single base station 602 as Figure 6 shown.

[0086] At block 710, one or both of the TRPs 412, 414 may optionally measure the measurement gap 722. The measurement gap 722 may be a period of time during which the UE 104 is not scheduled to transmit or receive data. Alternatively, the UE 104 may perform antenna calibration measurements during the measurement gap 722. In some implementations, the TRPs 412, 414 may select the number and period of the measurement gaps based on the capabilities of the TRPs 412, 414. For example, the number and period of the measurement gaps are based on at least one of the following: the number of panels at two or more TRPs, the antenna array geometry and size of the panels at two or more TRPs, the maximum transmit power level at two or more TRPs, the existing antenna calibration inaccuracies at two or more TRPs, the number of layers from each TRP, the array gain required in the downlink at the UE or in the uplink at two or more TRPs, or the steering angle of the beams in the beamformed transmissions at two or more TRPs. In some implementations, the number and period of the measurement gaps may be based on the thermal overhead associated with each TRP. The TRPs 412, 414 may communicate via the backhaul link to exchange information about TRP capabilities and thermal overhead.

[0087] One or more of the TRPs 412, 414 may send a request 720 for one or more UEs 104 to perform antenna calibration measurements during the measurement gap 722. The TRPs 412, 414 may select one or more UEs based on at least one of the following: the capabilities of the one or more UEs, the power or thermal overhead of the one or more UEs, the data rate requirements of the one or more UEs, or the reliability requirements of the one or more UEs.

[0088] The request 720 may be an RRC message or a MAC control element (MAC-CE). In one aspect, the request 720 may utilize joint beamforming from the TRPs 412, 414. Alternatively, a single TRP may send the request 720. The request 720 may configure the measurement gap for performing antenna calibration measurements. In some implementations, the request 720 includes a joint QCL mapping for receiving transmissions from the TRPs 412, 414 to one or more UEs 104.

[0089] Two or more of the TRPs 412, 414 may coordinate the joint transmission of the reference signal 730 during the measurement gap. For example, TRP1 412 may send the reference signal 732, and TRP2 414 may send the reference signal 734. The reference signal 730 may be, for example, a channel state information reference signal (CSI-RS). In some implementations, two or more of the TRPs 412, 414 may perform multi-user multiple-input multiple-output (MU-MIMO) transmission of the reference signal 730 to multiple UEs.

[0090] At block 740, UE 104 may measure reference signal 730 during measurement gap 722. UE 104 may measure the phase and / or amplitude of a subset of antenna elements on the UE side in response to transmissions from a subset of other antenna elements at TRPs 412, 414. In some implementations, UE 104 may perform measurements using a fixed receive beam for transmissions from at least one of two or more TRPs and a different receive beam for transmissions from at least another one of two or more TRPs. For example, as Figure 5 shown, UE 104 may fix receive beam 552 for TRP2 414 while attempting different receive beams 550a-d for TRP1 412. In other implementations, for example, as Figure 6 shown, UE 104 may perform measurements on MU-MIMO transmissions using different receive beams to measure the effects of sidelobes or beam nulls.

[0091] UE 104 may send a report 750 including the results of the measurements in block 740. For example, report 750 may include the measured phase and / or amplitude values. UE 104 may send report 750 to one or more of TRPs 412, 414. In one aspect, UE 104 may send to a single TRP1 412. TRP1 412 may forward report 750 as report 752 via a backhaul network (e.g., Figure 1 backhaul link 134 in

[0092] At block 760, TRP1 412 may calibrate one or more antenna elements based on antenna calibration measurements. For example, TRP1 412 may compare the expected phase and / or amplitude values with the received phase and / or amplitude values in report 750. TRP1 412 may adjust the phase and amplitude settings of at least one antenna element or one or more transmit chain components for the array to reduce the difference between the expected and received values and thus reduce the effectiveness of beamforming. Similarly, in block 762, TRP2 414 may also calibrate one or more antenna elements based on the antenna calibration measurements in report 750.

[0093] Figure 8 is a conceptual data flow diagram 800 showing the data flow between different units / components in an example base station 802, which may be an example of base station 102 including antenna calibration component 120.

[0094] As described above with respect to Figure 1As discussed, the antenna calibration component 120 may include a request component 122, a coordination component 124, a reporting component 126, and a calibration component 128. The antenna calibration component 120 may also include a receiver component 850 and a transmitter component 852. The receiver component 850 may include, for example, an RF receiver for receiving the signals described herein. The transmitter component 852 may include, for example, an RF transmitter for transmitting the signals described herein. In some implementations, the transmitter component 852 may include two or more TRPs, or may be associated with two or more TRPs. For example, as Figure 6 shown, the base station 602 may include a TRP1 612 and a TRP2 614, both of which may be included in the transmitter component 852 or controlled by the transmitter component 854. In one aspect, the receiver component 850 and the transmitter component 852 may be co-located in a transceiver. In some implementations, the antenna calibration component 120 may include a selection component 848 configured to select one or more UEs to perform antenna calibration measurements.

[0095] The request component 122 may generate a request 720 for performing antenna calibration measurements on one or more UEs. The request component 122 may initiate an antenna calibration process when a potential antenna calibration problem is detected. For example, the request component 122 may initiate a calibration process in response to a significant difference (e.g., greater than a threshold) between the downlink signal-to-noise ratio (SNR) and the uplink SNR, which may indicate that the lower SNR is due to antenna calibration rather than channel conditions. As another example, if the downlink SNR and the uplink SNR are poor (e.g., below a threshold) for multiple UEs, the request component 122 may initiate a calibration process. The request component 122 may determine a measurement gap 722 for the calibration process. The number and period of the measurement gap 722 may be based on the capabilities 860 of the TRPs 412, 414. For example, the request component 122 may determine the number and period of the measurement gap based on at least one of the following: the number of panels at two or more TRPs, the antenna array geometry and size of the panels at two or more TRPs, the maximum transmit power level at two or more TRPs, the existing antenna calibration inaccuracy at two or more TRPs, the number of layers from each TRP, the array gain required in the downlink at the UE or in the uplink at two or more TRPs, or the steering angle of the beam in the beamformed transmission at two or more TRPs. In some implementations, the number and period of the measurement gap may be based on the thermal overhead 862 associated with each TRP. In some implementations, the request component 122 may determine a QCL mapping 864 for calibration. The request component 122 may provide the coordination component 124 with a request including the configuration of the measurement gap and the QCL mapping 864.

[0096] In an implementation including the selection component 848, the selection component 848 may select a UE to perform antenna calibration measurements. The selection component 848 may select the UE based on the UE capabilities 866. The receiver component 850 may receive a configuration message indicating the UE capabilities 866 and provide the UE capabilities 866 to the selection component 848. The selection component 848 may select a UE based on at least one of the following: the capabilities of the one or more UEs, the power or thermal overhead of the one or more UEs, the data rate requirements of the one or more UEs, or the reliability requirements of the one or more UEs. For example, the selection component 848 may select a UE that has the ability to perform calibration measurements, that has an acceptable thermal overhead, and that is still able to meet the data rate requirements and reliability requirements when performing the measurements. The selection component 848 may indicate the selected UE to the request component 122.

[0097] The coordination component 124 may receive a request 720 from the request component 122. The coordination component 124 may send the request 720 to the UE via the transmitter component 852. For example, the coordination component 124 may send the request 720 as a MAC-CE or RRC configuration message. In some implementations, the coordination component 124 may coordinate the transmission of the request 720 with another base station. For example, the coordination component 124 may send the request 720 to another base station via the backhaul link 134. The coordination component 124 may also coordinate the transmission of reference signals between two or more TRPs during a measurement gap 722. For example, when the base station 802 includes two or more TRPs, the coordination component 124 may send a reference signal via the transmitter component 852, TRP1 612, and TRP2 614. When one or more TRPs are located at another base station, the coordination component 124 may indicate the QCL mapping 864 and timing information to the other base station via the backhaul link 134.

[0098] The receiver component 850 may receive a report 750 from one or more UEs. The receiver component 850 may provide the report 750 to the reporting component 126. In some implementations, the reporting component 126 may receive a report 752 from the backhaul link 134 via the coordination component 124. The reporting component 126 may forward the report 750 as the report 752 to another base station via the coordination component 124 and the backhaul link 134. The reporting component 126 may extract measurement values such as the phase 820 and amplitude 822 from the report 750 or the report 752. The reporting component 126 may provide the measurement values to the calibration component 128.

[0099] The calibration component 128 can compare the measured values of the received phase 820 and amplitude 822 with the phase and amplitude of the transmitted reference signal. The calibration component 128 can provide calibration information to the transmitter component 852 to adjust one or more antenna elements of the TRP1 612 and / or the TRP2 614. When another TRP is located at another base station, the other base station can include an antenna calibration component 120 that adjusts the other TRP based on the report 752.

[0100] Figure 9 FIG. 900 is a conceptual data flow diagram showing the data flow between different units / components in an exemplary UE 904, which exemplary UE can be an example of the UE 104 and includes an antenna calibration assistance component 140.

[0101] As discussed above with respect to Figure 1 The antenna calibration assistance component 140 can include a request component 142, a measurement component 144, and a reporting component 146. The antenna calibration assistance component 140 can also include a receiver component 870 and a transmitter component 872. The receiver component 870 can include, for example, a radio frequency (RF) receiver for receiving the signals described herein. The transmitter component 872 can include, for example, an RF transmitter for transmitting the signals described herein. In one aspect, the receiver component 870 and the transmitter component 872 can be co-located in a transceiver.

[0102] The receiver component 870 can receive a request 720 from one or more TRPs. The receiver component 870 can provide the request 720 to the request component 142. The receiver component 870 can receive a reference signal, such as a CSI-RS, during a measurement gap. The receiver component 870 can provide the reference signal to the measurement component 144.

[0103] The request component 142 can receive the request 720 from the receiver component 870. The request component 142 can extract the configuration of the measurement gap 722 and the QCL mapping 864 from the request 720. The request component 142 can provide the configuration of the measurement gap 722 and the QCL mapping 864 to the measurement component 144.

[0104] The measurement component 144 can receive the configuration of the measurement gap 722 and the QCL mapping 864 from the request component 142. During the measurement gap, the measurement component 144 can control the receiver component 870 to receive a reference signal 730 according to the QCL mapping 864. The measurement component 144 can receive the reference signal from the receiver component 870. The measurement component 144 can perform antenna calibration measurements on the reference signal. For example, the measurement component 144 can determine the measured values of the phase 820 and / or the amplitude 822. The measurement component 144 can provide the measurement to the reporting component 146.

[0105] The reporting component 146 can receive measurement values from the measurement component 144. The reporting component 146 can generate a report 750 that includes the measurement values. The reporting component 146 can send the report 750 to one or more TRPs via the transmitter component 872.

[0106] Figure 10 is a flowchart of an example method 1000 for performing a network calibration process on two or more TRPs. The method 1000 can be performed by a base station (e.g., base station 102, which can include a memory 376 and which can be the entire base station 102 or a component of the base station 102, such as the antenna calibration component 120, the TX processor 316, the RX processor 370, or the controller / processor 375). The method 1000 can be performed by the antenna calibration component 120 that communicates with the antenna calibration assistance component 140 of the UE 104. The method 1000 can be performed by the antenna calibration component 120 at a first base station that communicates with the antenna calibration component 120 at a second base station.

[0107] At block 1010, the method 1000 can optionally include selecting one or more UEs based on at least one of: the capabilities of the one or more UEs, the power or thermal overhead of the one or more UEs, the data rate requirements of the one or more UEs, or the reliability requirements of the one or more UEs. In one aspect, for example, the base station 102, the controller / processor 375, and / or the TX processor 316 can execute the antenna calibration component 120 and / or the selection component 848 to select one or more UEs based on at least one of: the capabilities of the one or more UEs, the power or thermal overhead of the one or more UEs, the data rate requirements of the one or more UEs, or the reliability requirements of the one or more UEs. Thus, the base station 102, the controller / processor 375, and / or the TX processor 316 that execute the antenna calibration component 120 and / or the selection component 848 can provide a unit for selecting one or more UEs based on at least one of: the capabilities of the one or more UEs, the power or thermal overhead of the one or more UEs, the data rate requirements of the one or more UEs, or the reliability requirements of the one or more UEs.

[0108] At block 1020, method 1000 may include sending a request for one or more UEs to perform antenna calibration measurements for two or more TRPs during a measurement gap. In one aspect, for example, base station 102, controller / processor 375, and / or TX processor 316 may execute antenna calibration component 120 and / or request component 122 to send a request 720 for one or more UEs 104 to perform antenna calibration measurements for two or more TRPs during measurement gap 722. Request 720 may configure measurement gap 722 for performing antenna calibration measurements. In some implementations, the number and periodicity of the measurement gaps are based on at least one of the following: the number of panels at two or more TRPs, the antenna array geometry and size of the panels at two or more TRPs, the maximum transmit power level of two or more TRPs, the existing antenna calibration inaccuracy at two or more TRPs, the number of layers from each TRP, the array gain required in the downlink at the UE or in the uplink at two or more TRPs, or the steering angle of the beams in the beamformed transmissions at two or more TRPs. In some implementations, the number and period of the measurement gaps may be based on the thermal overhead associated with each TRP. In some implementations, the request includes a joint QCL mapping to one or more UEs 104 for receiving transmissions from TRPs 412, 414. Thus, base station 102, controller / processor 375, and / or TX processor 316 that execute antenna calibration component 120 and / or request component 122 may provide a unit for sending a request for one or more UEs to perform antenna calibration measurements for two or more TRPs during a measurement gap.

[0109] At block 1030, method 1000 may include coordinating the transmission of reference signals between two or more TRPs during a measurement gap. In one aspect, for example, base station 102, controller / processor 375, and / or TX processor 316 may execute antenna calibration component 120 and / or coordination component 124 to coordinate the transmission of reference signals between two or more TRPs during a measurement gap. For example, coordination component 124 may coordinate the transmission of reference signals according to QCL mapping 864. For example, at sub-block 1032, coordination component 124 may perform MU-MIMO transmission to multiple UEs (e.g., as Figure 6 shown). Thus, base station 102, controller / processor 375, and / or TX processor 316 that execute antenna calibration component 120 and / or coordination component 124 may provide a unit for coordinating the transmission of reference signals between two or more TRPs during a measurement gap.

[0110] At block 1040, method 1000 may include receiving, from one or more UEs, a report based on antenna calibration measurements. In one aspect, for example, base station 102, controller / processor 375, and / or TX processor 316 may execute antenna calibration component 120 and / or selection component 848 to receive, from one or more UEs, a report 750 based on antenna calibration measurements. Report 750 may include measurements using a fixed receive beam for transmissions from at least one of two or more TRPs and different receive beams for transmissions from at least another one of the two or more TRPs. Thus, base station 102, controller / processor 375, and / or TX processor 316 that execute antenna calibration component 120 and / or selection component 848 may provide a unit for receiving, from one or more UEs, a report based on antenna calibration measurements.

[0111] At block 1050, method 1000 may optionally include transmitting the received report to another one of two or more TRPs via a backhaul network. In one aspect, for example, base station 102, controller / processor 375, and / or TX processor 316 may execute antenna calibration component 120 and / or coordination component 124 to transmit the received report to another one of two or more TRPs via a backhaul network. Thus, base station 102, controller / processor 375, and / or TX processor 316 that execute antenna calibration component 120 and / or coordination component 124 may provide a unit for transmitting the received report to another one of two or more TRPs via a backhaul network.

[0112] At block 1060, method 1000 may include calibrating one or more antenna elements of two or more TRPs based on antenna calibration measurements. In one aspect, for example, base station 102, controller / processor 375, and / or TX processor 316 may execute antenna calibration component 120 and / or calibration component 128 to calibrate one or more antenna elements of two or more TRPs based on antenna calibration measurements. Thus, base station 102, controller / processor 375, and / or TX processor 316 that execute antenna calibration component 120 and / or calibration component 128 may provide a unit for calibrating one or more antenna elements of two or more TRPs based on antenna calibration measurements.

[0113] Figure 11is a flowchart of an example method 1100 for UE-assisted network calibration procedures for two or more TRPs. Method 1100 may be performed by a UE (such as UE 104, which may include a memory 360 and may be the entire UE 104 or a component of UE 104, such as antenna calibration assistance component 140, TX processor 368, RX processor 356, or controller / processor 359). Method 1100 may be performed by antenna calibration assistance component 140 in communication with antenna calibration component 120 of base station 102.

[0114] At block 1110, method 1100 may include: receiving a request to perform antenna calibration measurements for two or more TRPs during a measurement gap. In one aspect, for example, UE 104, RX processor 356, and / or controller / processor 359 may execute antenna calibration assistance component 140 and / or request component 142 to receive a request 720 to perform antenna calibration measurements for two or more TRPs 412, 414 during measurement gap 722. For example, request 720 may be a MAC-CE or RRC message that indicates the resources on which to receive reference signal 730 and the QCL mapping for receiving reference signal 730. UE 104 may suspend signal transmission with the serving cell during measurement gap 722. Thus, UE 104, RX processor 356, and / or controller / processor 359, which execute antenna calibration assistance component 140 and / or request component 142, may provide a unit for receiving a request to perform antenna calibration measurements for two or more TRPs during a measurement gap.

[0115] At block 1120, method 1100 may include: performing antenna calibration measurements on reference signals from two or more TRPs during a measurement gap. In one aspect, for example, UE 104, RX processor 356, and / or controller / processor 359 may execute antenna calibration assistance component 140 and / or measurement component 144 to perform antenna calibration measurements on reference signals 730 from two or more TRPs during a measurement gap. For example, at sub-block 1122, measurement component 144 may perform measurements using a fixed receive beam for transmissions from at least one of the two or more TRPs and a different receive beam for transmissions from at least another of the two or more TRPs. As another example, at sub-block 1124, measurement component 144 may perform measurements of MU-MIMO transmissions using different receive beams to measure the effects of sidelobes or beam nulls. Thus, UE 104, RX processor 356, and / or controller / processor 359, which execute antenna calibration assistance component 140 and / or measurement component 144, may provide a unit for performing antenna calibration measurements on reference signals from two or more TRPs during a measurement gap.

[0116] At block 1130, method 1100 may include: sending a report to at least one of the TRPs based on antenna calibration measurements. In one aspect, for example, UE 104, TX processor 368, and / or controller / processor 359 may execute antenna calibration assistance component 140 and / or reporting component 146 to send a report to at least one of the TRPs based on antenna calibration measurements. Accordingly, UE 104, TX processor 368, and / or controller / processor 359 that execute antenna calibration assistance component 140 and / or reporting component 146 may provide a unit for sending a report to at least one of the TRPs based on antenna calibration measurements.

[0117] Figure 12 is a flowchart of an example method 1200 for a UE to perform a network calibration process based on measurements of two or more TRPs. Method 1200 may be performed by a UE (such as UE 104, which may include memory 360 and may be the entire UE 104 or a component of UE 104, such as antenna calibration component 120, TX processor 368, RX processor 356, or controller / processor 359). Method 1200 may be performed by antenna calibration component 120 at UE 350 that communicates with antenna calibration assistance component 140 of base station 310.

[0118] At block 1210, method 1200 may include: sending a request for the UE to send a reference signal to two or more TRPs during a measurement gap for antenna calibration measurements. In one aspect, for example, UE 104, TX processor 368, and / or controller / processor 359 may execute antenna calibration component 120 and / or request component 122 to send a request for UE 104 to send a reference signal to two or more TRPs 412, 414 during measurement gap 722 for antenna calibration measurements. Accordingly, UE 104, TX processor 368, and / or controller / processor 359 that execute antenna calibration assistance component 140 and / or request component 142 may provide a unit for sending a request for the UE to send a reference signal to two or more TRPs during a measurement gap for antenna calibration measurements.

[0119] At block 1220, method 1200 may include transmitting a reference signal to two or more TRPs during a measurement gap. In one aspect, for example, UE 104, TX processor 368, and / or controller / processor 359 may execute antenna calibration component 120 and / or coordination component 124 to transmit a reference signal to two or more TRPs during a measurement gap. Accordingly, UE 104, TX processor 368, and / or controller / processor 359 that execute antenna calibration component 120 and / or coordination component 124 may provide a unit for transmitting a reference signal to two or more TRPs during a measurement gap.

[0120] At block 1230, method 1200 may include receiving a report based on antenna calibration measurements from two or more TRPs. In one aspect, for example, UE 104, RX processor 356, and / or controller / processor 359 may execute antenna calibration component 120 and / or reporting component 126 to receive a report based on antenna calibration measurements from two or more TRPs. Accordingly, UE 104, RX processor 356, and / or controller / processor 359 that execute antenna calibration component 120 and / or reporting component 126 may provide a unit for receiving a report based on antenna calibration measurements from two or more TRPs.

[0121] At block 1240, method 1200 may include calibrating one or more antenna elements of the UE based on antenna calibration measurements. In one aspect, for example, UE 104, RX processor 356, and / or controller / processor 359 may execute antenna calibration component 120 and / or calibration component 128 to calibrate one or more antenna elements of UE 104 based on antenna calibration measurements. Accordingly, UE 104, RX processor 356, and / or controller / processor 359 that execute antenna calibration component 120 and / or calibration component 128 may provide a unit for calibrating one or more antenna elements of the UE based on antenna calibration measurements.

[0122] It is to be understood that the specific order or hierarchy of the blocks in the disclosed process / flowchart is an illustration of example methods. It is to be understood that based on design preferences, the specific order or hierarchy of the blocks in the process / flowchart may be rearranged. Additionally, some blocks may be combined or omitted. The appended method claims present the elements of the various blocks in example order and are not meant to be limited to the specific order or hierarchy presented.

[0123] Some additional example clauses

[0124] Implementing examples are described in the following numbered clauses:

[0125] 1. A method of wireless communication, comprising:

[0126] Send a request to perform antenna calibration measurements for two or more transmission and reception points (TRPs) during a measurement gap for one or more user equipment (UEs);

[0127] Coordinate the transmission of reference signals between the two or more TRPs during the measurement gap;

[0128] Receive a report based on the antenna calibration measurements from the one or more UEs; and

[0129] Calibrate one or more antenna elements of the two or more TRPs based on the antenna calibration measurements.

[0130] 2. The method according to clause 1, further comprising: selecting the one or more UEs based on at least one of: the capabilities of the one or more UEs, the power or thermal overhead of the one or more UEs, the data rate requirements of the one or more UEs, or the reliability requirements of the one or more UEs.

[0131] 3. The method according to clause 1 or 2, wherein the request configures the measurement gap for performing the antenna calibration measurements.

[0132] 4. The method according to clause 3, wherein the number and period of the measurement gaps are based on at least one of: the number of panels at the two or more TRPs, the antenna array geometry and size of the panels at the two or more TRPs, the maximum transmit power level at the two or more TRPs, the existing antenna calibration inaccuracies at the two or more TRPs, the number of layers from each TRP, the array gain required in the downlink at the UE or in the uplink at the two or more TRPs, or the steering angle of the beams in the beamformed transmissions at the two or more TRPs.

[0133] 5. The method according to clause 3, wherein the number and period of the measurement gaps are based on the thermal overhead associated with each TRP.

[0134] 6. The method according to any one of clauses 1-5, further comprising: transmitting the received report to another TRP among the two or more TRPs via a backhaul network.

[0135] 7. The method according to any one of clauses 1-6, wherein the request includes a joint quasi-co-location (QCL) mapping for receiving transmissions from the TRPs to the one or more UEs.

[0136] 8. The method according to any one of clauses 1 - 7, wherein the report includes: measurements using a fixed receive beam for transmission from at least one of the two or more TRPs and a different receive beam for transmission from at least another one of the two or more TRPs.

[0137] 9. The method according to any one of clauses 1 - 7, wherein coordinating the transmission of the reference signal during the measurement gap between the two or more TRPs includes: performing multi - user multiple - input multiple - output (MU - MIMO) transmission to a plurality of UEs.

[0138] 10. A method for wireless communication by a user equipment (UE), comprising:

[0139] receiving a request to perform antenna calibration measurements during a measurement gap for two or more transmit - receive points (TRPs);

[0140] performing the antenna calibration measurements on reference signals from the two or more TRPs during the measurement gap; and

[0141] sending a report to at least one of the TRPs based on the antenna calibration measurements.

[0142] 11. The method according to clause 10, wherein performing the antenna calibration measurements includes: performing measurements using a fixed receive beam for transmission from at least one of the two or more TRPs and a different receive beam for transmission from at least another one of the two or more TRPs.

[0143] 12. The method according to clause 10 or 11, wherein the request includes a joint quasi - co - location (QCL) mapping for receiving transmissions from the two or more TRPs to the UE.

[0144] 13. The method according to clause 10, wherein performing the antenna calibration measurements includes: performing measurements of multi - user multiple - input multiple - output (MU - MIMO) transmission using different receive beams to measure the effects of sidelobes or beam nulls.

[0145] 14. The method according to any one of clauses 10 - 13, wherein the request configures the measurement gap for performing the antenna calibration measurements.

[0146] 15. The method according to any one of clauses 10 - 13, wherein the UE pauses signal transmission with a serving cell during the measurement gap.

[0147] 16. A method for wireless communication at a user equipment (UE), comprising:

[0148] Send a request for the UE to send a reference signal to two or more transmit - receive points (TRPs) during a measurement gap for antenna calibration measurement;

[0149] Send the reference signal to the two or more TRPs during the measurement gap;

[0150] Receive a report based on the antenna calibration measurement from the two or more TRPs; and

[0151] Calibrate one or more antenna elements of the UE based on the antenna calibration measurement.

[0152] 17. The method according to clause 16, wherein the TRP configures the measurement gap in response to the request.

[0153] 18. A device for wireless communication, comprising:

[0154] A memory that stores computer - executable instructions; and

[0155] At least one processor coupled to the memory and configured to execute the computer - executable instructions to perform the following operations:

[0156] Send a request for one or more user equipment (UEs) to perform antenna calibration measurement for two or more transmit - receive points (TRPs) during a measurement gap;

[0157] Coordinate the transmission of reference signals among the two or more TRPs during the measurement gap;

[0158] Receive a report based on the antenna calibration measurement from the one or more UEs; and

[0159] Calibrate one or more antenna elements of the two or more TRPs based on the antenna calibration measurement.

[0160] 19. The device according to clause 18, wherein the at least one processor is configured to select the one or more UEs based on at least one of: the capabilities of the one or more UEs, the power or thermal overhead of the one or more UEs, the data rate requirements of the one or more UEs, or the reliability requirements of the one or more UEs.

[0161] 20. The device according to clause 18 or 19, wherein the request configures the measurement gap for performing the antenna calibration measurement.

[0162] 21. The apparatus according to clause 20, wherein the number and period of the measurement gaps are based on at least one of the following: the number of panels at the two or more TRPs, the antenna array geometry and size of the panels at the two or more TRPs, the maximum transmit power level at the two or more TRPs, the existing antenna calibration inaccuracies at the two or more TRPs, the number of layers from each TRP, the array gain required in the downlink at the UE or in the uplink at the two or more TRPs, or the steering angle of the beam in the beamformed transmission at the two or more TRPs.

[0163] 22. The apparatus according to clause 20, wherein the number and period of the measurement gaps are based on the thermal overhead associated with each TRP.

[0164] 23. The apparatus according to any one of clauses 18 - 22, wherein the at least one processor is configured to: transmit the received report to another TRP among the two or more TRPs via a backhaul network.

[0165] 24. The apparatus according to any one of clauses 18 - 23, wherein the request includes a joint quasi - co - location (QCL) mapping for receiving transmissions from the TRP to the one or more UEs.

[0166] 25. The apparatus according to any one of clauses 18 - 24, wherein the report includes: measurements using a fixed receive beam for transmissions from at least one TRP among the two or more TRPs and a different receive beam for transmissions from at least another TRP among the two or more TRPs.

[0167] 26. The apparatus according to any one of clauses 18 - 24, wherein the at least one processor is configured to: perform multi - user multiple - input multiple - output (MU - MIMO) transmission to multiple UEs.

[0168] 27. An apparatus for a user equipment (UE) for wireless communication, comprising:

[0169] a memory that stores computer - executable instructions; and

[0170] at least one processor coupled to the memory and configured to execute the computer - executable instructions to perform the following operations:

[0171] receive a request to perform antenna calibration measurements during measurement gaps for two or more transmit - receive points (TRPs);

[0172] Perform the antenna calibration measurement on reference signals from the two or more TRPs during the measurement gap;

[0173] and

[0174] Send a report to at least one of the TRPs based on the antenna calibration measurement.

[0175] 28. The apparatus according to clause 27, wherein the at least one processor is configured to: perform measurements using a fixed receive beam for transmissions from at least one of the two or more TRPs and a different receive beam for transmissions from at least another one of the two or more TRPs.

[0176] 29. The apparatus according to clause 27 or 28, wherein the request includes a joint quasi - co - location (QCL) mapping for receiving transmissions from the two or more TRPs to the UE.

[0177] 30. The apparatus according to clause 27, wherein the at least one processor is configured to: perform measurements of multi - user multiple - input multiple - output (MU - MIMO) transmissions using different receive beams to measure the impact of sidelobes or beam nulls.

[0178] 31. The apparatus according to any one of clauses 27 - 30, wherein the request configures the measurement gap for performing the antenna calibration measurement.

[0179] 32. The apparatus according to any one of clauses 27 - 31, wherein the UE suspends signal transmission with the serving cell during the measurement gap.

[0180] 33. An apparatus for a user equipment (UE) for wireless communication, comprising:

[0181] a memory that stores computer - executable instructions; and

[0182] at least one processor coupled to the memory and configured to execute the computer - executable instructions to:

[0183] Send a request for the UE to send reference signals to two or more transmit - receive points (TRPs) during a measurement gap for antenna calibration measurement;

[0184] Send the reference signals to the two or more TRPs during the measurement gap;

[0185] Receive a report based on the antenna calibration measurement from the two or more TRPs; and

[0186] Calibrate one or more antenna elements of the UE based on the antenna calibration measurement.

[0187] 34. The apparatus according to clause 33, wherein the TRP configures the measurement gap in response to the request.

[0188] 35. A device for wireless communication, comprising:

[0189] A unit for sending a request for performing antenna calibration measurements at two or more transmission and reception points (TRPs) during a measurement gap for one or more user equipments (UEs);

[0190] A unit for coordinating the transmission of reference signals between the two or more TRPs during the measurement gap;

[0191] A unit for receiving a report based on the antenna calibration measurement from the one or more UEs; and

[0192] A unit for calibrating one or more antenna elements of the two or more TRPs based on the antenna calibration measurement.

[0193] 36. The apparatus according to clause 35, further comprising: a unit for selecting the one or more UEs based on at least one of the following: the capabilities of the one or more UEs, the power or thermal overhead of the one or more UEs, the data rate requirements of the one or more UEs, or the reliability requirements of the one or more UEs.

[0194] 37. The apparatus according to clause 35 or 36, wherein the request configures the measurement gap for performing the antenna calibration measurement.

[0195] 38. The apparatus according to clause 37, wherein the number and period of the measurement gaps are based on at least one of the following: the number of panels at the two or more TRPs, the antenna array geometry and size of the panels at the two or more TRPs, the maximum transmit power level at the two or more TRPs, the existing antenna calibration inaccuracies at the two or more TRPs, the number of layers from each TRP, the array gain required in the downlink at the UE or in the uplink at the two or more TRPs, or the steering angle of the beams in the beamformed transmission at the two or more TRPs.

[0196] 39. The apparatus according to clause 37, wherein the number and period of the measurement gaps are based on the thermal overhead associated with each TRP.

[0197] 40. The apparatus according to any one of clauses 35 - 39 further comprises: a unit for transmitting the received report to another one of the two or more TRPs via a backhaul network.

[0198] 41. The apparatus according to any one of clauses 35 - 40, wherein the request comprises a joint quasi - co - location (QCL) mapping for receiving transmissions from the TRP to the one or more UEs.

[0199] 42. The apparatus according to any one of clauses 35 - 41, wherein the report comprises: measurements using a fixed reception beam for transmissions from at least one of the two or more TRPs and different reception beams for transmissions from at least another one of the two or more TRPs.

[0200] 43. The apparatus according to any one of clauses 35 - 41, wherein the unit for coordinating the transmission of the reference signal during the measurement gap between the two or more TRPs is configured to: perform multi - user multiple - input multiple - output (MU - MIMO) transmission to multiple UEs.

[0201] 44. An apparatus for wireless communication of a user equipment (UE), comprising:

[0202] a unit for receiving a request to perform antenna calibration measurements during a measurement gap for two or more transmit - receive points (TRPs);

[0203] a unit for performing the antenna calibration measurements on reference signals from the two or more TRPs during the measurement gap; and

[0204] a unit for sending a report to at least one of the TRPs based on the antenna calibration measurements.

[0205] 45. The apparatus according to clause 44, wherein the unit for performing the antenna calibration measurements is configured to: perform measurements using a fixed reception beam for transmissions from at least one of the two or more TRPs and different reception beams for transmissions from at least another one of the two or more TRPs.

[0206] 46. The apparatus according to clause 44 or 45, wherein the request comprises a joint quasi - co - location (QCL) mapping for receiving transmissions from the two or more TRPs to the UE.

[0207] 47. The apparatus according to clause 44, wherein the unit for performing the antenna calibration measurement is configured to: perform measurements of multi-user multiple-input multiple-output (MU-MIMO) transmission using different receive beams to measure the impact of sidelobes or beam nulls.

[0208] 48. The apparatus according to any one of clauses 44-47, wherein the request configures the measurement gap for performing the antenna calibration measurement.

[0209] 49. The apparatus according to any one of clauses 44-48, wherein the UE pauses signal transmission with the serving cell during the measurement gap.

[0210] 50. An apparatus for wireless communication at a user equipment (UE), comprising:

[0211] a unit for sending a request for the UE to send a reference signal to two or more transmit-receive points (TRPs) during a measurement gap for antenna calibration measurement;

[0212] a unit for sending the reference signal to the two or more TRPs during the measurement gap;

[0213] a unit for receiving a report based on the antenna calibration measurement from the two or more TRPs; and

[0214] a unit for calibrating one or more antenna elements of the UE based on the antenna calibration measurement.

[0215] 51. The apparatus according to clause 50, wherein the TRP configures the measurement gap in response to the request.

[0216] 52. A non-transitory computer-readable medium storing computer-executable code that, when executed by a processor, causes the processor to perform the following operations:

[0217] Send a request for one or more user equipment (UEs) to perform antenna calibration measurements for two or more transmit receive points (TRPs) during a measurement gap;

[0218] Coordinate the transmission of reference signals among the two or more TRPs during the measurement gap;

[0219] Receive reports based on the antenna calibration measurements from the one or more UEs; and

[0220] Calibrate one or more antenna elements of the two or more TRPs based on the antenna calibration measurement.

[0221] 53. The non-transitory computer-readable medium according to clause 52 further includes: code for selecting the one or more UEs based on at least one of the following: the capabilities of the one or more UEs, the power or thermal overhead of the one or more UEs, the data rate requirements of the one or more UEs, or the reliability requirements of the one or more UEs.

[0222] 54. The non-transitory computer-readable medium according to clause 52 or 53, wherein the request configures the measurement gap for performing the antenna calibration measurement.

[0223] 55. The non-transitory computer-readable medium according to clause 54, wherein the number and period of the measurement gaps are based on at least one of the following: the number of panels at the two or more TRPs, the antenna array geometry and size of the panels at the two or more TRPs, the maximum transmit power level at the two or more TRPs, the existing antenna calibration inaccuracies at the two or more TRPs, the number of layers from each TRP, the array gain required in the downlink at the UE or in the uplink at the two or more TRPs, or the steering angle of the beams in the beamformed transmission at the two or more TRPs.

[0224] 56. The non-transitory computer-readable medium according to clause 54, wherein the number and period of the measurement gaps are based on the thermal overhead associated with each TRP.

[0225] 57. The non-transitory computer-readable medium according to any one of clauses 52-56 further includes: code for transmitting the received report to another TRP among the two or more TRPs via a backhaul network.

[0226] 58. The non-transitory computer-readable medium according to any one of clauses 52-57, wherein the request includes a joint quasi-co-location (QCL) mapping for receiving transmissions from the TRP to the one or more UEs.

[0227] 59. The non-transitory computer-readable medium according to any one of clauses 52-58, wherein the report includes: measurements using a fixed receive beam for transmissions from at least one TRP among the two or more TRPs and different receive beams for transmissions from at least another TRP among the two or more TRPs.

[0228] 60. The non-transitory computer-readable medium according to any one of clauses 52 - 58, wherein the code for coordinating the transmission of the reference signal during the measurement gap between the two or more TRPs includes: code for performing multi-user multiple-input multiple-output (MU-MIMO) transmission to multiple UEs.

[0229] 61. A non-transitory computer-readable medium storing computer-executable code that, when executed by a processor of a user equipment (UE), causes the processor to perform the following operations:

[0230] Receive a request to perform antenna calibration measurements during a measurement gap for two or more transmit-receive points (TRPs);

[0231] Perform the antenna calibration measurements on reference signals from the two or more TRPs during the measurement gap; and

[0232] Send a report to at least one of the TRPs based on the antenna calibration measurements.

[0233] 62. The non-transitory computer-readable medium according to clause 61, wherein the code for performing the antenna calibration measurements includes: performing measurements using a fixed receive beam for transmissions from at least one of the two or more TRPs and a different receive beam for transmissions from at least another of the two or more TRPs.

[0234] 63. The non-transitory computer-readable medium according to clause 61 or 62, wherein the request includes a joint quasi-co-location (QCL) mapping for receiving transmissions from the two or more TRPs to the UE.

[0235] 64. The non-transitory computer-readable medium according to clause 61, wherein the code for performing the antenna calibration measurements includes: code for performing measurements of multi-user multiple-input multiple-output (MU-MIMO) transmissions using different receive beams to measure the effects of sidelobes or beam nulls.

[0236] 65. The non-transitory computer-readable medium according to any one of clauses 61 - 64, wherein the request configures the measurement gap for performing the antenna calibration measurements.

[0237] 66. The non-transitory computer-readable medium according to any one of clauses 61 - 65, wherein the UE pauses signal transmission with the serving cell during the measurement gap.

[0238] 67. A non-transitory computer-readable medium storing computer-executable code that, when executed by a processor of a user equipment (UE), causes the processor to perform the following operations:

[0239] Send a request for the UE to send a reference signal to two or more transmit-receive points (TRPs) during a measurement gap for antenna calibration measurements;

[0240] Send the reference signal to the two or more TRPs during the measurement gap;

[0241] Receive a report based on the antenna calibration measurements from the two or more TRPs; and

[0242] Calibrate one or more antenna elements of the UE based on the antenna calibration measurements.

[0243] 68. The non-transitory computer-readable medium according to clause 67, wherein the TRP configures the measurement gap in response to the request.

[0244] The foregoing description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but are to be accorded the full scope consistent with the claim language, wherein reference to an element in the singular is not intended to mean "one and only one" unless explicitly so stated, but rather "one or more." The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any aspect described herein as "exemplary" is not necessarily to be construed as preferred or superior to other aspects. Unless otherwise expressly stated, the term "some" refers to one or more. Combinations such as "at least one of A, B, or C," "one or more of A, B, or C," "at least one of A, B, and C," "one or more of A, B, and C," and "any combination of A, B, C, or thereof" include any combination of A, B, and / or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as "at least one of A, B, or C," "one or more of A, B, or C," "at least one of A, B, and C," "one or more of A, B, and C," and "any combination of A, B, C, or thereof" can be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combination can include one or more members or several members of A, B, or C. All structural and functional equivalents of the elements of the various aspects described throughout this disclosure are expressly incorporated herein by reference and are intended to be encompassed by the claims, these structural and functional equivalents being known or later to be known to those of ordinary skill in the art. Further, nothing disclosed herein is intended to be dedicated to the public, whether or not such disclosure is expressly recited in the claims. The words "module," "mechanism," "element," "device," etc. are not intended to be substitutes for the word "unit." Thus, no claim element is to be construed as a functional module unless the element is expressly recited using the phrase "means for."

Claims

1. A method for wireless communication, comprising: sending a request to perform antenna calibration measurements for two or more transmit receive points (TRPs) during a measurement gap for one or more user equipments (UEs), wherein the request includes a joint quasi co-location (QCL) mapping for receiving a joint transmission of reference signals from all of the two or more TRPs to the one or more UEs; coordinating, based on the joint QCL mapping, a joint transmission of reference signals from all of the two or more TRPs between the two or more TRPs during the measurement gap; receiving, from the one or more UEs, a report based on the antenna calibration measurements; and calibrating one or more antenna elements of the two or more TRPs based on the antenna calibration measurements.

2. The method according to claim 1, further comprising: selecting the one or more UEs based on at least one of: capabilities of the one or more UEs, power or thermal overhead of the one or more UEs, data rate requirements of the one or more UEs, or reliability requirements of the one or more UEs.

3. The method according to claim 1, wherein, the request configures the measurement gap for performing the antenna calibration measurements.

4. The method according to claim 3, wherein, the number and period of the measurement gaps are based on at least one of: the number of panels at the two or more TRPs, the antenna array geometry and size of the panels at the two or more TRPs, the maximum transmit power level at the two or more TRPs, existing antenna calibration inaccuracies at the two or more TRPs, the number of layers from each TRP, the array gain required in the downlink at the one or more UEs or in the uplink at the two or more TRPs, or the steering angle of the beam in the beamformed transmission at the two or more TRPs.

5. The method according to claim 3, wherein, the number and period of the measurement gaps are based on the thermal overhead associated with each TRP.

6. The method according to claim 1, further comprising: transmitting the received report to another TRP among the two or more TRPs via a backhaul network.

7. The method according to claim 1, wherein, the report includes measured phase values and amplitude values.

8. The method according to claim 1, wherein, the report includes: measurements using a fixed receive beam for transmissions from at least one of the two or more TRPs and different receive beams for transmissions from at least another of the two or more TRPs.

9. The method according to claim 1, wherein, coordinating the transmission of the reference signals between the two or more TRPs during the measurement gap includes: performing multi-user multiple input multiple output (MU-MIMO) transmission to multiple UEs.

10. A method for wireless communication by a user equipment (UE), comprising: Receive a request to perform antenna calibration measurements during a measurement gap for two or more transmit receive points (TRPs), where the request includes a joint quasi co-location (QCL) mapping for receiving joint transmissions of reference signals from all of the two or more TRPs to the UE; Based on the joint QCL mapping, perform the antenna calibration measurements during the measurement gap on the joint transmissions of reference signals from all of the two or more TRPs; and Send a report to at least one of the TRPs based on the antenna calibration measurements.

11. The method according to claim 10, wherein, Performing the antenna calibration measurements includes: performing measurements using a fixed receive beam for transmissions from at least one of the two or more TRPs and a different receive beam for transmissions from at least another one of the two or more TRPs.

12. The method according to claim 10, wherein, The report includes measured phase values and amplitude values.

13. The method according to claim 10, wherein, Performing the antenna calibration measurements includes: performing measurements of multi-user multiple input multiple output (MU-MIMO) transmissions using different receive beams to measure the effects of sidelobes or beam nulls.

14. The method according to claim 10, wherein, The request configures the measurement gap for performing the antenna calibration measurements.

15. The method according to claim 10, wherein, The UE pauses signal transmission with the serving cell during the measurement gap.

16. An apparatus for wireless communication, comprising: a memory that stores computer-executable instructions; and at least one processor coupled to the memory and configured to execute the computer-executable instructions to perform the following operations: Send a request to perform antenna calibration measurements during a measurement gap for two or more transmit receive points (TRPs) for one or more user equipments (UEs), where the request includes a joint quasi co-location (QCL) mapping for receiving joint transmissions of reference signals from all of the two or more TRPs to the one or more UEs; Based on the joint QCL mapping, coordinate joint transmissions of reference signals from all of the two or more TRPs among the two or more TRPs during the measurement gap; Receive a report from the one or more UEs based on the antenna calibration measurements; and Calibrate one or more antenna elements of the two or more TRPs based on the antenna calibration measurements.

17. The apparatus according to claim 16, wherein, The at least one processor is configured to: select the one or more UEs based on at least one of: the capabilities of the one or more UEs, the power or thermal overhead of the one or more UEs, the data rate requirements of the one or more UEs, or the reliability requirements of the one or more UEs.

18. The apparatus according to claim 16, wherein, The request configures the measurement gap for performing the antenna calibration measurement.

19. The apparatus according to claim 18, wherein, the number and period of the measurement gaps are based on at least one of the following: the number of panels at the two or more TRPs, the antenna array geometry and size of the panels at the two or more TRPs, the maximum transmit power level at the two or more TRPs, the existing antenna calibration inaccuracies at the two or more TRPs, the number of layers from each TRP, the required array gain in the downlink at the one or more UEs or in the uplink at the two or more TRPs, or the steering angle of the beams in the beamformed transmissions at the two or more TRPs.

20. The apparatus according to claim 18, wherein, the number and period of the measurement gaps are based on the thermal overhead associated with each TRP.

21. The apparatus according to claim 16, wherein, the at least one processor is configured to: transmit the received report to another one of the two or more TRPs via a backhaul network.

22. The apparatus according to claim 16, wherein, the report includes the measured phase values and amplitude values.

23. The apparatus according to claim 16, wherein, the report includes: measurements using a fixed receive beam for transmissions from at least one of the two or more TRPs and different receive beams for transmissions from at least another one of the two or more TRPs.

24. The apparatus according to claim 16, wherein, the at least one processor is configured to: perform multi-user multiple-input multiple-output (MU-MIMO) transmission of the reference signal to multiple UEs during the measurement gap.

25. An apparatus for a user equipment (UE) for wireless communication, comprising: a memory that stores computer-executable instructions; and at least one processor coupled to the memory and configured to execute the computer-executable instructions to: receive a request to perform an antenna calibration measurement during a measurement gap for two or more transmit receive points (TRPs), wherein the request includes a joint quasi co-location (QCL) mapping for receiving a joint transmission of reference signals from all of the two or more TRPs to the UE; perform the antenna calibration measurement on the joint transmission of reference signals from all of the two or more TRPs during the measurement gap based on the joint QCL mapping; and send a report to at least one of the TRPs based on the antenna calibration measurement.

26. The apparatus according to claim 25, wherein, the at least one processor is configured to: perform the measurement using a fixed receive beam for transmissions from at least one of the two or more TRPs and different receive beams for transmissions from at least another one of the two or more TRPs.

27. The apparatus according to claim 25, wherein, the report includes the measured phase value and amplitude value.

28. The apparatus according to claim 25, wherein, the at least one processor is configured to: perform the measurement of the multi-user multiple-input multiple-output (MU-MIMO) transmission using different receive beams to measure the influence of sidelobes or beam nulls.

29. The apparatus according to claim 25, wherein, the request configures the measurement gap for performing the antenna calibration measurement.

30. The apparatus according to claim 25, wherein, the UE suspends signal transmission with the serving cell during the measurement gap.

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