Method, apparatus, and computer program for a communication network

Abstract

Example embodiments of the present disclosure relate to methods, apparatuses, and computer programs for a communication network. A method performed by a UE is provided, the method comprising performing a first transmission of a SRS on a first antenna port, AP, and performing a second transmission of a second SRS on a second AP, wherein the first AP and the second AP are different, and determining a first phase difference between the first transmission and the second transmission. The method further comprises receiving, from a network entity, a resource allocation for an uplink physical channel transmission, and performing, based on the resource allocation, a third transmission on the first AP on a first symbol and a fourth transmission on the second AP on a second symbol. The method further comprises determining a second phase difference between the third transmission and the fourth transmission, and performing, based on the resource allocation and a difference between the first phase difference and the second phase difference, at least one physical channel MIMO transmission to the network entity.

Description

Technical Field

[0001] The various examples disclosed relate to methods, apparatuses, and computer programs. In particular, some examples relate to methods, apparatuses, and computer programs for communication networks. Background Technology

[0002] A communication network can be viewed as a facility that enables communication between two or more communication devices, or provides communication devices with access to a data network. Mobile or wireless communication networks are an example of a communication network. Communication devices may be served by application servers.

[0003] Such communication networks operate according to standards provided by, for example, 3GPP (3rd Generation Partnership Project) or ETSI (European Telecommunications Standards Institute). An example of such a standard is the so-called 5G (fifth generation) standard provided by 3GPP. Summary of the Invention

[0004] Some examples of this disclosure will be described in conjunction with certain aspects. These aspects are not intended to indicate key or essential features of embodiments of this disclosure, nor are they intended to limit its scope. Other features, aspects, and elements will be apparent to those skilled in the art in conjunction with this disclosure. For example, it should be understood that additional aspects may be provided by combination of any two or more of the aspects described below.

[0005] According to a first aspect, a method performed by a user equipment (UE) is provided, the method comprising: performing a first transmission of a first sounding reference signal (SRS) on a first antenna port (AP) and a second transmission of a second SRS on a second AP, wherein the first AP and the second AP are different; determining a first phase difference between the first transmission and the second transmission; receiving a resource allocation from a network entity for uplink physical channel transmission; performing a third transmission on a first symbol on the first AP and a fourth transmission on a second symbol on the second AP based on the resource allocation; determining a second phase difference between the third transmission and the fourth transmission; and performing a multiple-input multiple-output (MIMO) transmission to at least one physical channel of the network entity based on the resource allocation and the difference between the first phase difference and the second phase difference, wherein precoding of at least one MIMO layer associated with at least two antenna ports for the at least one physical channel MIMO transmission is delayed by at least one symbol in the sequence of allocated UL symbols of the resource allocation.

[0006] According to a second aspect, a UE is provided, comprising: means for causing the UE to perform at least the following: performing a first transmission of a first sounding reference signal (SRS) on a first antenna port (AP) and a second transmission of a second SRS on a second AP, wherein the first AP and the second AP are different; determining a first phase difference between the first transmission and the second transmission; receiving a resource allocation from a network entity for uplink physical channel transmission; performing a third transmission on a first symbol on the first AP and a fourth transmission on a second symbol on the second AP based on the resource allocation; determining a second phase difference between the third transmission and the fourth transmission; and performing a multiple-input multiple-output (MIMO) transmission to at least one physical channel of the network entity based on the resource allocation and the difference between the first phase difference and the second phase difference, wherein precoding of at least one MIMO layer associated with at least two antenna ports for the at least one physical channel MIMO transmission is delayed by at least one symbol in the sequence of allocated UL symbols of the resource allocation.

[0007] According to a third aspect, a UE is provided, comprising: at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to at least: perform a first transmission of a first sounding reference signal (SRS) on a first antenna port (AP) and a second transmission of a second SRS on a second AP, wherein the first AP and the second AP are different; determine a first phase difference between the first transmission and the second transmission; receive a resource allocation from a network entity for uplink physical channel transmission; based on the resource allocation, perform a third transmission on a first symbol on the first AP and a fourth transmission on a second symbol on the second AP; determine a second phase difference between the third transmission and the fourth transmission; and based on the resource allocation and the difference between the first phase difference and the second phase difference, perform a multiple-input multiple-output (MIMO) transmission to at least one physical channel of the network entity, wherein precoding associated with at least two antenna ports for at least one MIMO layer of the at least one physical channel MIMO transmission is delayed by at least one symbol in the sequence of allocated UL symbols of the resource allocation.

[0008] According to a fourth aspect, a UE is provided, comprising: circuitry configured to perform the following: performing a first transmission of a first sounding reference signal (SRS) on a first antenna port (AP) and a second transmission of a second SRS on a second AP, wherein the first AP and the second AP are different; determining a first phase difference between the first transmission and the second transmission; receiving a resource allocation from a network entity for uplink physical channel transmission; based on the resource allocation, performing a third transmission on a first symbol on the first AP and a fourth transmission on a second symbol on the second AP; determining a second phase difference between the third transmission and the fourth transmission; and performing a multiple-input multiple-output (MIMO) transmission to at least one physical channel of the network entity based on the resource allocation and the difference between the first phase difference and the second phase difference, wherein precoding of at least one MIMO layer associated with at least two antenna ports for the at least one physical channel MIMO transmission is delayed by at least one symbol in the sequence of allocated UL symbols of the resource allocation.

[0009] According to a fifth aspect, a computer program is provided, including instructions that, when executed by a UE, cause the UE to at least: perform a first transmission of a first sounding reference signal (SRS) on a first antenna port (AP) and a second transmission of a second SRS on a second AP, wherein the first AP and the second AP are different; determine a first phase difference between the first transmission and the second transmission; receive a resource allocation from a network entity for uplink physical channel transmission; based on the resource allocation, perform a third transmission on a first symbol on the first AP and a fourth transmission on a second symbol on the second AP; determine a second phase difference between the third transmission and the fourth transmission; and based on the resource allocation and the difference between the first phase difference and the second phase difference, perform a multiple-input multiple-output (MIMO) transmission to at least one physical channel of the network entity, wherein precoding associated with at least two antenna ports for at least one MIMO layer of the at least one physical channel MIMO transmission is delayed by at least one symbol in the sequence of allocated UL symbols of the resource allocation.

[0010] The following applies to each of the first through fifth aspects above (e.g., one or more, including all of them).

[0011] In some examples, for at least one physical channel MIMO transmission, the corresponding MIMO layer of the at least one physical channel MIMO transmission is transmitted on at least two APs of the UE.

[0012] In some examples, one of the following is true: the first symbol and the second symbol are the same; the first symbol and the second symbol are adjacent symbols within a time slot; or the first symbol and the second symbol are adjacent symbols across two adjacent time slots.

[0013] In some examples, the UE is also made to perform: precoding at least two antenna ports associated with at least one MIMO layer for at least one physical channel MIMO transmission based on the difference between a first phase difference and a second phase difference.

[0014] In some examples, the UE is also instructed to: transmit an instruction to a network entity for at least one symbol, wherein the at least one symbol is used for phase adjustment for at least one physical channel MIMO transmission.

[0015] In some examples, at least one symbol indicates a gap in the time used for uplink scheduling.

[0016] In some examples, the indication of at least one symbol includes one of the following: an indication of one symbol; an indication of two symbols, wherein the two symbols are the last two symbols in a time slot of the frame; or an indication of three symbols, wherein two of the three symbols are the last two symbols in a time slot of the frame, and one of the three symbols is the first symbol in another time slot of the frame.

[0017] In some examples, the indication of at least one symbol includes: a first indication of two or more symbols associated with a first UL MIMO rank supported by the UE, and a second indication of two or more symbols associated with a second UL MIMO rank supported by the UE.

[0018] In some examples, the UE is also made to perform: receive a Transport Precoding Matrix Indicator (TPMI) from a network entity, wherein the execution of at least one physical channel MIMO transmission is also based on the TPMI.

[0019] In some examples, for precoding, the phase difference between at least two antenna ports is based on: TPMI, and the difference between the first phase difference and the second phase difference.

[0020] In some examples, the execution of at least one physical channel MIMO transmission includes: delaying the precoding of at least one MIMO layer associated with at least two antenna ports in the sequence by at least one symbol based on an indication of at least one symbol.

[0021] In some examples, the UE is also made to perform: measuring the phase for a third transmission; measuring the phase for a fourth transmission, wherein a second phase difference between the third and fourth transmissions is based on: a comparison between the phase for the third transmission and the phase for the fourth transmission; and determining the difference between the first and second phase differences.

[0022] In some examples, the phase for the third transmission is measured at the output of the UE's first power amplifier, which is associated with the third transmission, and the phase for the fourth transmission is measured at the output of the UE's second power amplifier, which is associated with the fourth transmission.

[0023] In some examples, the UE is also instructed to transmit the following instruction to the network entity: the UE supports symbol-delayed coherent UL transmission.

[0024] In some examples, the UE supports the transmission of indications for coherent UL transmissions with symbol delay, which are transmitted together with indications for at least one symbol.

[0025] In some examples, the third and fourth transmissions are one of the following: physical uplink shared channel transmission or physical uplink control channel transmission.

[0026] In some examples, determining the first phase difference includes: measuring the phase for a first transmission; measuring the phase for a second transmission; and comparing the phase for the first transmission with the phase for the second transmission to determine the first phase difference.

[0027] According to a sixth aspect, a method performed by a network entity is provided, the method comprising: receiving from a user equipment (UE) a first transmission of a first sounding reference signal (SRS) on a first antenna port (AP) and a second transmission of a second SRS on a second AP, wherein the first AP and the second AP are different; transmitting to the UE a resource allocation for uplink physical channel transmission; receiving from the UE a third transmission on a first symbol on the first AP and a fourth transmission on a second symbol on the second AP; and, based on the resource allocation, receiving from the UE at least one physical channel multiple-input multiple-output (MIMO) transmission, wherein precoding of at least one MIMO layer associated with at least two antenna ports for at least one physical channel MIMO transmission is delayed by at least one symbol in the sequence of allocated UL symbols of the resource allocation.

[0028] According to a seventh aspect, a network entity is provided, comprising: components for causing the network entity to perform at least the following: receiving from a user equipment (UE) a first transmission of a first sounding reference signal (SRS) on a first antenna port (AP) and a second transmission of a second SRS on a second AP, wherein the first AP and the second AP are different; transmitting to the UE a resource allocation for uplink physical channel transmission; receiving from the UE a third transmission on a first symbol on the first AP and a fourth transmission on a second symbol on the second AP; and receiving from the UE, based on the resource allocation, at least one physical channel multiple-input multiple-output (MIMO) transmission, wherein precoding of at least one MIMO layer associated with at least two antenna ports for at least one physical channel MIMO transmission is delayed by at least one symbol in the sequence of allocated UL symbols of the resource allocation.

[0029] According to an eighth aspect, a network entity is provided, comprising: at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the network entity to perform at least: receiving from a user equipment (UE) a first transmission of a first sounding reference signal (SRS) on a first antenna port (AP) and a second transmission of a second SRS on a second AP, wherein the first AP and the second AP are different; transmitting to the UE a resource allocation for uplink physical channel transmission; receiving from the UE a third transmission on a first symbol on the first AP and a fourth transmission on a second symbol on the second AP; and, based on the resource allocation, receiving from the UE at least one physical channel multiple-input multiple-output (MIMO) transmission, wherein precoding of at least one MIMO layer associated with at least two antenna ports for the at least one physical channel MIMO transmission is delayed by at least one symbol in the sequence of allocated UL symbols of the resource allocation.

[0030] According to a ninth aspect, a network entity is provided, comprising: circuitry configured to perform the following: receiving from a user equipment (UE) a first transmission of a first sounding reference signal (SRS) on a first antenna port (AP) and a second transmission of a second SRS on a second AP, wherein the first AP and the second AP are different; transmitting to the UE a resource allocation for uplink physical channel transmission; receiving from the UE a third transmission on a first symbol on the first AP and a fourth transmission on a second symbol on the second AP; and, based on the resource allocation, receiving from the UE at least one physical channel multiple-input multiple-output (MIMO) transmission, wherein precoding of at least one MIMO layer associated with at least two antenna ports for at least one physical channel MIMO transmission is delayed by at least one symbol in the sequence of allocated UL symbols of the resource allocation.

[0031] According to a tenth aspect, a computer program is provided, including instructions that, when executed by a network entity, cause the network entity to perform at least: receiving from a user equipment (UE) a first transmission of a first sounding reference signal (SRS) on a first antenna port (AP) and a second transmission of a second SRS on a second AP, wherein the first AP and the second AP are different; transmitting to the UE a resource allocation for uplink physical channel transmission; receiving from the UE a third transmission on a first symbol on the first AP and a fourth transmission on a second symbol on the second AP; and, based on the resource allocation, receiving from the UE at least one physical channel multiple-input multiple-output (MIMO) transmission, wherein precoding of at least one MIMO layer associated with at least two antenna ports for at least one physical channel MIMO transmission is delayed by at least one symbol in the sequence of allocated UL symbols of the resource allocation.

[0032] The following applies to each of the above-mentioned aspects 6 through 10 (e.g., one or more, including all of them).

[0033] In some examples, the network entity is also made to perform: receiving an instruction from the UE for at least one symbol, wherein the at least one symbol is used for phase adjustment for at least one physical channel MIMO transmission; and Resource allocation is determined based on the indication of at least one symbol.

[0034] In some examples, the indication of at least one symbol includes one of the following: an indication of one symbol; an indication of two symbols, wherein the two symbols are the last two symbols in a time slot of a frame; or an indication of three symbols, wherein two of the three symbols are the last two symbols in a time slot of a frame, and one of the three symbols is the first symbol in another time slot of a frame.

[0035] In some examples, the network entity is also made to perform: determine a Transport Precoding Matrix Indicator (TPMI) based on a first and a second transmission received from the UE; and transmit the TPMI to the UE.

[0036] In some examples, network entities are also instructed to: receive from the UE an indication that the UE supports symbol-delayed coherent UL transmission; initiate coherent uplink MIMO transmission for the UE based on the indication; and transmit SRS resource allocation to the UE for SRS transmission.

[0037] In some examples, physical channel MIMO transmission is one of the following: physical uplink shared channel transmission or physical uplink control channel transmission. A computer product stored on the medium can enable the device to perform the methods described herein.

[0038] A non-transitory computer-readable medium includes program instructions that, when executed by a device, cause the device to perform the methods described herein.

[0039] An electronic device may include the means as described herein.

[0040] Various other aspects and additional embodiments are also described in the detailed description below and in the appended claims.

[0041] The subject matter of the independent claims is provided for several aspects. Several other aspects are defined in the dependent claims. Embodiments that do not fall within the scope of the claims should be interpreted as examples that aid in understanding this disclosure.

[0042] List of abbreviations: AP: Antenna Port AN: Network Access BS: Base Station CB: Codebook based CN: Core Network CSI-RS: Channel State Information Reference Signal DL: Downlink EIRP: Equivalent Isotropic Radiated Power gNB: gNodeB LTE: Long Term Evolution MIMO: Multiple Input Multiple Output NCB: Non-codebook based NG-RAN: Next Generation Radio Access Network NF: Network Functions NR: New Radio NW: Network PA: Power Amplifier PLL: Phase-locked loop PLMN: Public Land Mobile Network PUCCH: Physical Uplink Control Channel PUSCH: Physical Uplink Shared Channel RAN: Radio Access Network RF: Radio Frequency SRS: Detection Reference Signal TPMI: Transport Precoding Matrix Indicator UE: User Equipment UL: Uplink 3GPP: Third Generation Partnership Project (Registered™) 5G: Fifth Generation 5GC: 5G Core Network 5G-AN: 5G Radio Access Network 5GS: 5G system. Attached Figure Description

[0043] Some examples will now be described by way of illustrative and non-limiting example only, with reference to the accompanying drawings, in which: Figure 1 A schematic representation of a 5G communication system is shown; Figure 2 It shows the use of Figure 1 A schematic diagram of a 5G communication system device; Figure 3 A schematic representation of a communication device is shown; Figure 4 The signaling and operation diagrams for the codebook-based uplink MIMO process are shown. Figure 5 An example of a tabular representation of the codebook for single-layer transmission is shown; Figure 6 A schematic representation of the frame structure of the UE, including the first frame and the second frame, is shown; Figure 7 A schematic representation of the radio components of a UE with two Tx / Rx chains is shown; Figure 8 A schematic representation of a frame structure including multiple time slots configured for coherent UL transmission with symbol delay is shown; Figure 9 Example signaling and operation diagrams for user equipment and base stations used for coherent UL transmission with symbol delay are shown; Figure 10 An example schematic representation of the radio components of a UE with two Tx / Rx chains is shown; Figure 11 A flowchart of an example method executed by the device is shown; Figure 12 A flowchart illustrating an example method executed by the device is shown; and Figure 13 A schematic diagram of the device is shown. Detailed Implementation

[0044] Multiple-input multiple-output (MIMO) technology is a technique in wireless communication that utilizes multiple antennas at both the transmitter and receiver, as seen in 5G networks. By employing these multiple antennas, MIMO systems can transmit and receive data simultaneously, resulting in increased data throughput and improved signal quality. Traditional MIMO systems typically use a relatively small number of antennas at both ends of the communication link, such as two or four. However, massive MIMO systems can use dozens or even hundreds of antennas, allowing for a significant increase in the number of spatial streams that can be transmitted concurrently.

[0045] UL MIMO can be codebook-based (CB) or non-codebook-based (NCB). In CB MIMO, the user equipment (UE) relies on the gNB to derive the Transport Precoding Matrix Indicator (TPMI), and the gNB informs the UE of the precoding values ​​to be used for PUSCH transmission. This differs from NCB MIMO, where the UE is expected to derive the precoding values ​​for PUSCH transmission based on the received DL reference signal. The precoding process for CB MIMO utilizing four antenna ports (APs) on both the gNB and UE sides is shown below. Figure 4 .

[0046] Figure 4 The signaling and operation diagrams for the codebook-based uplink MIMO process are shown. Figure 4 The example given is based on a 5G communication system. As networks evolve towards 6G and higher, capacity is expected to increase.

[0047] In S401, the gNB transmits up to 2×16 orthogonal uncoded Channel State Information Reference Signals (CSI-RS) (each from a (virtual) AP) with a uniform radiation pattern covering the gNB cell's angular domain. These cell-specific CSI-RS can be transmitted sequentially or simultaneously (e.g., in groups of eight for 5G). Simultaneous CSI-RS transmission reduces the Equivalent Isotropic Radiated Power (EIRP) for each configured CSI-RS beam. However, since the UL is a power-limited link, such EIRP reduction is rarely a problem.

[0048] In S402, the UE receives each non-precoded CSI-RS on all receiver links and determines the optimal PMI from the appropriate predefined codebook. The selected PMI is transmitted back to the gNB via uplink control information (UCI).

[0049] In S403, the gNB will request the UE to transmit uncoded SRS from each UL antenna port. This DL transmission can be performed at the gNB using a single precoded beam. In this example, there are 4 APs.

[0050] In S404, non-precoded SRS resources are transmitted from the UE to the gNB (e.g., according to 3GPP TS 38.214). SRSs can be transmitted sequentially or simultaneously (as shown), depending on the UE's capabilities. Simultaneously transmitted SRSs will reduce the power of each SRS to meet the maximum combined Tx power requirement at the UE, and thus reduce coverage. The gNB estimates the channel based on the received SRS (which can utilize a precoded receive beam (determined in S402)) and determines the optimal TPMI from an appropriate predefined codebook.

[0051] In S405, the gNB transmits the rank and the determined ("optimal") TPMI to the UE. This DL transmission to the UE can be performed at the gNB using a single precoded beam.

[0052] In S406, the UE uses the obtained UL precoding to transmit the Physical Uplink Shared Channel (PUSCH) to the gNB.

[0053] In the context of wireless communication, coherence refers to the fact that the relative phase and amplitude (i.e., power) between uplink (UL) transmitted signals or between UL multiple-input multiple-output (MIMO) streams are known, so that the transmission can be tuned / optimized to improve UL performance.

[0054] Coherent UL MIMO is a transmission technology that enables a user equipment (UE) to simultaneously transmit each MIMO layer to the network across multiple antenna ports (and / or multiple antennas). The goal of coherent UL MIMO is to enhance uplink performance, capacity, and reliability in cellular networks (e.g., in 5G and towards 6G). In contrast, a non-coherent UE transmits each MIMO layer via UL MIMO on a single antenna port. By utilizing multiple antenna ports at the UE, coherent UL MIMO can significantly increase data transmission rates and overall system capacity. However, requirements exist for coherent UL MIMO (e.g., defined by 3GPP) where the UE must adhere to maintain coherent / concurrent transmission. This will be discussed in more detail below.

[0055] Predefined UL codebooks are defined for different UE configurations, for example in 3GPP TS 38.211. Figure 4 An example is shown, which relates to single-layer transmission and includes precoded values ​​(TPMI) for antenna ports 1, 2, and 4.

[0056] Figure 5 An example tabular representation of the definition codebook for single-layer transmission is shown. In the first column 501, there are TPMI indices ranging from 0 to 27 (i.e., 28 different TPMIs). In the second column 503, there is a precoding matrix (W) associated with each TPMI index. This precoding matrix (W) is used for single-layer transmission using four antenna ports (APs) with transform precoding enabled.

[0057] like Figure 5 As shown, the TPMI indices ranging from 0 to 3 (i.e., the first four precoding matrices W) are (only) associated with a single AP. This is indicated by a single "1" and three "0"s in the matrix. Each element of the precoding matrix is ​​associated with an AP. Therefore, if there is no coherence between all APs on the UE, one of the TPMI indices 0 to 3 will be used. In this way, an incoherent UE will be configured with one of the first four indices (0 to 3), which only requires the UE to transmit from one of the four APs. A semi-coherent UE (e.g., coherent between two of the four APs) can be additionally configured with TPMI indices 4 to 11 (i.e., 0 to 11), where UL transmissions are performed on the two coherent APs and have a delta phase (phase difference) indicated by the TPMI. A fully coherent UE (e.g., coherent between all four APs) will be configured with all TPMI indices 0 to 27, where UL transmissions are performed on all four coherent APs and have a delta phase (phase difference) indicated by the TPMI.

[0058] Codebook entries involving two or more APs (i.e., TPMI indexes) can only be used if the UE is able to maintain phase and amplitude coherence among at least some of the configured APs. As mentioned above, the UE must follow specific requirements to maintain coherent UL MIMO transmissions. For example, in 3GPP TS 38.101, for coherent UL MIMO, Table 6.4D.4-1 (copied from Table 1 below) indicates the maximum permissible difference between the relative power error and phase error measured at the same antenna connector in any time slot within a specific time window from the most recent SRS of any two coherent antenna ports in the scheduled antenna ports for UL transmission at their respective antenna connectors, and the error value measured at that last SRS.

[0059]

[0060] Table 1: Maximum permissible difference between relative phase error and relative power error in a given time slot and relative phase error and relative power error measured at the SRS of the most recent transmission (excerpted from Table 6.4D.4-1 in 3GPP TS 38.101-1).

[0061] According to the requirements in Table 1, UL transmissions from the UE distributed across two or more APs will require the UE to maintain a maximum phase error of 40 degrees and a maximum power difference of 4 dB for a duration (window) of 20 milliseconds (between two or more APs). However, the aforementioned phase and power requirements may be difficult to meet for mobile devices such as the UE. For example, due to port-specific phase-locked loops (PLLs), frequency offsets may occur across different UE antenna ports. Furthermore, unintended port-specific phase transitions may occur due to handover from DL to UL.

[0062] The transceivers in the UE are typically implemented using separate local oscillators (LOs) and phase-locked loops (PLLs) for each supported DL and UL layer. This allows the UE to control each LO individually for each DL and / or UL layer depending on the duplex scheme (e.g., Frequency Division Duplex (FDD) or Time Division Duplex (TDD)). UL MIMO is typically used in TDD system bands because they have higher maximum bandwidth and better spectral efficiency (e.g., TDD does not have unused duplex guard bands like FDD). A question associated with TDD and UL coherent transmissions concerns the following: the UE switches from Tx / UL (for SRS transmission) to Rx / DL (for receiving TPMI from the gNB) and then switches back to Tx / UL for PUSCH transmission. This switching occurs... Figure 4 The diagram shows that the UE performs a transmission in S404, then switches to receiving in S405, and then switches back to transmission in S406. Another illustration of this switch from Tx to Rx to Tx is shown in... Figure 6 As shown in the image.

[0063] Figure 6 A schematic representation of the frame structure for a UE, including the first frame and the second frame, is shown.

[0064] The first frame 601 includes ten time slots, arranged as follows: downlink (D), D, D, special (S), uplink (U), D, D, D, S, U. The second frame 603 also includes ten time slots, arranged in the same order: D, D, D, S, U, D, D, D, S, U.

[0065] In the fifth time slot 605 of frame 601 (an uplink time slot), the UE transmits SRS. In the seventh time slot 607 of frame 601 (a downlink time slot), the UE receives TPMI. In the tenth time slot 609 of frame 601 (an uplink time slot), the UE transmits PUSCH. Between the transmission of SRS and the reception of TPMI, the UE performs a handover from Tx to Rx. Then, between the reception of TPMI and the transmission of PUSCH, the UE switches back to Tx.

[0066] For power efficiency and to minimize interference, a dedicated PLL is typically used instead of switching and routing the local oscillator (LO) signal to more links in the Rx and Tx links. Typical UE behavior is to disable the power amplifier (PA), LO, and PLL on the Tx link when configured for DL, as this reduces potential self-interference and contributes to power savings at the UE. When the PLL is re-enabled (e.g., during a handover to prepare for transmission), the absolute phase of the PLL will be random, and consequently, the absolute phase of the LO will also be random, resulting in random relative phases between any two UL APs when the UE switches from Rx to Tx. Furthermore, switching the transmitter PA from "ON" to "OFF" and then back to "ON" can also lead to unpredictable phase shifts that depend on the PA design and UL power level and are difficult to characterize. A schematic representation of the radio components of an example UE with two Tx / Rx links is shown in [the diagram]. Figure 7 As shown in the diagram. The functional block in the UE that may cause phase differences due to this handover is... Figure 7 The text is highlighted (e.g., PLL, PA, etc.).

[0067] Figure 7 A schematic representation of the radio components of a UE with two Tx / Rx links is shown.

[0068] UE 700 includes a digital baseband block 701 connected to radio transceiver 703. Digital baseband block 701 includes a clock reference generator and a transmit quadrature / in-phase (Q / I) signal generator. Radio transceiver 703 includes a first Tx / Rx link 705 and a second Tx / Rx link 707, wherein the first Tx / Rx link 705 is associated with a first antenna 709, and the second Tx / Rx link 707 is associated with a second antenna 711. The first Tx / Rx link 705 includes (attached to other components) a first PLL 713 and a first PA 715. The first PLL 713 and the first PA 715 may cause phase differences due to handovers performed by the UE between Tx and Rx configurations. The second Tx / Rx link 707 includes (attached to other components) a second PLL 717 and a second PA 719. The second PLL 717 and the second PA 719 may cause phase differences due to the handover performed by the UE between the Tx configuration and the Rx configuration.

[0069] As discussed above, the relative phase difference between the two APs when transmitting SRS from the UE to the gNB for deriving the optimal TPMI is not maintained when the UE is scheduled for subsequent PUSCH transmissions. This is due to the UE switching between DL and UL configurations. For example, the UE may be in DL configuration to receive TPMI from the gNB and then switch to UL configuration for PUSCH Tx. As a result, the UE may not meet the requirements for coherent UL MIMO (e.g., TS 38.101-1).

[0070] Some previous systems have attempted to address this issue by keeping the UL functional blocks in the UE powered on during the DL time slot (e.g., keeping the PA, LO, PLL, and clock reference source powered on). However, this approach increases self-interference at the UE because the DL and UL links operate at the same frequency, which can severely impact DL performance. Furthermore, the PA is directly connected to the antenna and is only disconnected from it via a TDD Rx / Tx switch, and is only allowed to remain on during the DL time slot if the radiated power level is less than the 50 dBm / 1 MHz required for UE receive band coexistence. Receiver desensitization requires unrealistically high isolation in the Rx / Tx switches (e.g., for zero-IF (ZIF) or L-band IF (LIF) receiver architectures).

[0071] The following examples are designed to address one or more of the issues identified above.

[0072] In some examples, a method performed by a UE is provided, comprising: performing a first transmission of SRS on a first antenna port (AP) and a second transmission of a second SRS on a second AP, wherein the first AP and the second AP are different, and determining a first phase difference between the first transmission and the second transmission. The method further comprises: receiving a resource allocation from a network entity for uplink physical channel transmission, and based on the resource allocation, performing a third transmission on a first symbol on the first AP and a fourth transmission on a second symbol on the second AP. The method further comprises: determining a second phase difference between the third transmission and the fourth transmission, and based on the resource allocation and the difference between the first phase difference and the second phase difference, performing at least one physical channel MIMO transmission to the network entity, wherein precoding of at least one MIMO layer associated with at least two antenna ports for the at least one physical channel MIMO transmission is delayed by at least one symbol in the sequence of allocated UL symbols of the resource allocation.

[0073] In some examples, a method performed by a network entity is provided, comprising: receiving from a user equipment (UE) a first transmission of a first sounding reference signal (SRS) on a first antenna port (AP) and a second transmission of a second SRS on a second AP, wherein the first AP and the second AP are different, and transmitting to the UE a resource allocation for uplink physical channel transmission. The method further comprises: receiving from the UE a third transmission on a first symbol on the first AP and a fourth transmission on a second symbol on the second AP, and, based on the resource allocation, receiving from the UE at least one physical channel multiple-input multiple-output (MIMO) transmission, wherein precoding of at least one MIMO layer of the at least one physical channel MIMO transmission associated with at least two antenna ports is delayed by at least one symbol in the sequence of allocated UL symbols of the resource allocation.

[0074] The following will combine Figures 8 to 13 These examples will be described in more detail.

[0075] Before explaining the above examples in more detail, example communication devices capable of coherent UL MIMO transmission will be described (such as...). Figure 3 (As shown). This communication device is part of a communication system (such as...). Figure 1 (As shown). This communication device can communicate via a device (such as...) Figure 2 (as shown) and communication systems (such as Figure 1 The device communicates with one or more entities (as shown), and the device may be part of or included in a base station. As described above, the base station and the communication device can communicate with each other, thereby enabling the communication device to provide coherent UL MIMO transmissions to the base station.

[0076] To aid in understanding the technology upon which the described examples are based, combined with Figures 1 to 3 Briefly explain some general aspects of communication systems and equipment.

[0077] Figure 1 A schematic representation of a 5G communication system 100 is shown. In this way, Figure 1 Examples of communication networks to which the examples disclosed herein can be applied are shown. The communication network, or cellular communication network, may include a network node 110 providing one or more cells (e.g., cell 100) and a network node 112 providing one or more other cells (e.g., cell 102). Each cell may be, for example, a macrocell, microcell, femtocell, or picocell. The cell may define the coverage area or service area of ​​the corresponding access node.

[0078] Network node 110 can provide radio access to a communication network to user equipment (UE) 120 (one or more UEs). This radio access may include downlink (DL) communication from the network node to UE 120 and uplink (UL) communication from UE 120 to the network node. Examples of uplink channels include a Physical Uplink Control Channel (PUCCH) for transmitting control information and a Physical Uplink Shared Channel (PUSCH) for transmitting data toward the network. Examples of downlink channels include a Physical Downlink Control Channel (PDCCH) for transmitting control information and a Physical Downlink Shared Channel (PDSCH) for transmitting data toward the user equipment.

[0079] Multiple UEs 120 and 122 can exist in this system. Each of them can be served by the same or different network nodes 110 and 112. UEs can be configured with dual connectivity (DC), where a UE (e.g., UE 120) can connect to multiple network nodes 110 and 112. If a device-to-device (D2D) communication interface is established between them via a so-called side link (SL), UEs 120 and 122 can communicate with each other. For example, such D2D communication can be referred to as machine-to-machine, peer-to-peer (P2P) communication, or vehicle-to-vehicle (V2V) communication.

[0080] In a communication network with multiple network nodes, these nodes can connect to each other via interfaces. The LTE specification refers to such interfaces as X2 interfaces. The interface between an LTE node and a 5G node, or between two 5G nodes, can be called an Xn interface.

[0081] Network nodes 110 and 112 can also connect to the core network 116 of the communication network via another interface. The LTE specification designates the core network as the Evolved Packet Core (EPC), which may include, for example, a Mobility Management Entity (MME) and gateway nodes. The MME handles the mobility of terminal devices in a tracking area comprising multiple cells and handles signaling connections between the terminal devices and the core network. Gateway nodes handle data routing within the core network and to / from terminal devices. The 5G specification designates the core network as the 5G Core (5GC). The 5G Core may include, for example, Access and Mobility Management Functions (AMF) and User Plane Functions / Gateways (UPF) and other functions. The AMF handles Non-Access Stratum (NAS) signaling termination, NAS encryption and integrity protection, registration management, connection management, mobility management, access authentication and authorization, and security context management. For example, UPF nodes may support packet routing and forwarding, packet inspection, and Quality of Service (QoS) processing.

[0082] Figure 2 An example of device 200 is shown. Device 200 can be used for Figure 1 The 5G communication system. Device 200 can be used to control one or more network entities and / or network functions, such as... Figure 1 The device 200 is an entity of 5G-RAN or 5GC shown. The device 200 includes at least one random access memory (RAM) 211a, at least one read-only memory (ROM) 211b, at least one processor 212, 213, and an input / output interface 214. The at least one processor 212, 213 is coupled to the RAM 211a and ROM 211b. The at least one processor 212, 213 can be configured to execute appropriate software code 215. For example, the software code 215 can allow the execution of one or more steps to perform one or more of the present aspect or examples. The software code 215 can be stored in the ROM 211b. The device 200 can interconnect with another device 200 that controls another entity / function of 5G-AN or 5GC. In some examples, the device 200 can be configured to provide one or more functions of 5G-AN or 5GC. For example, the device 200 can be configured to perform at least some functionality of a specific function of 5G-AN or 5GC. For example, the device 200 can be configured to operate as a specific function of 5G-AN or 5GC. In an alternative example, device 200 may be configured to perform at least some of the functions of two or more of 5G-AN and / or 5GC. For example, device 200 may be configured to operate as two or more functions of 5G-AN and / or 5GC. Device 200 may include one or more circuits or circuit devices (not shown) that may be configured to perform one or more of the current aspects or examples.

[0083] Figure 3 An example of a communication device 300 is shown. The communication device 300 can be similar to... Figure 1 The communication device 102 shown is illustrated. Communication device 300 can be provided by any device capable of transmitting and receiving radio signals. Non-limiting examples of communication device 300 include user equipment, terminals, mobile stations (MS), or mobile devices such as mobile phones or so-called "smartphones," computers equipped with wireless interface cards or other wireless interface facilities (e.g., USB dongles), personal data assistants (PDAs) or tablets equipped with wireless communication capabilities, machine-type communication (MTC) devices, cellular Internet of Things (CIoT) devices, or land / sea / air vehicles such as cars, trucks, ships, airplanes, or drones, or any combination or similar. For example, communication device 300 can provide data communication for carrying communication. This communication can be one or more of voice, email, text messages, multimedia, data, machine data, etc.

[0084] Communication equipment 300 can receive signals via air or radio interface 307 through appropriate means for receiving, and can transmit signals via appropriate means for transmitting radio signals. Figure 3 In this diagram, the transceiver device is schematically represented by block 306. For example, transceiver device 306 can be provided via a radio section and an associated antenna arrangement. This antenna arrangement can be located inside or outside the mobile device.

[0085] The communication device 300 may be provided with at least one processor 301, at least one memory ROM 302a, at least one RAM 302b, and other possible components 303 for performing tasks designed to be performed with software and hardware assistance, including controlling access to and communication with access systems and other communication devices. The at least one processor 301 is coupled to the RAM 302b and ROM 302a. The at least one processor 301 may be configured to execute appropriate software code 308. For example, the software code 308 may allow the execution of one or more of the present aspects. The software code 308 may be stored in the ROM 302a. The communication device 300 may include one or more circuits or circuit arrangements (not shown) that may be configured to execute one or more of the present aspects or examples.

[0086] Processors, memory, and other related control devices may be provided on a suitable circuit board and / or in a chipset. This feature is indicated by reference numeral 304. The communication device may optionally have a user interface, such as a keyboard 305, a touchscreen or touchpad, a combination thereof, or the like. Optionally, depending on the type of device, one or more of a display, speaker, and microphone may be provided.

[0087] As discussed above, the relative phase difference between two APs during the transmission of SRS (for gNB derivation of optimal TPMI) from the UE to the gNB is not maintained when the UE is subsequently scheduled for PUSCH transmission. One reason for this phase difference not being maintained is that between the SRS transmission and the PUSCH, the UE is in a DL configuration to receive TPMI from the gNB (i.e., the UE switches from UL to DL and then back to UL). As a result, the UE may not meet the requirements for coherent UL MIMO. To address this, instead of performing UL transmission in the first (or first few) available uplink symbols, the UE uses two or more uplink symbols (during the UL transmission) to measure the phase difference for two or more APs and subsequently compensates for it. An example frame structure designed to address this issue, along with the associated UE configuration, is combined... Figure 8 Describe it.

[0088] Figure 8 A schematic representation of a frame structure including multiple time slots configured for coherent UL transmission with symbol delay is shown.

[0089] The first frame 801 and the second frame 803 are shown. A detailed view of special time slot 805 in the first frame 801 and a detailed view of the uplink time slot 807 adjacent to this special time slot 805 are shown. The structure of special time slot 805 is: D, D, D, D, D, D, D, D, D, gap (G), G, U, U. In this way, the special time slot has a 10:2:2 structure. Uplink time slot 807 has twelve uplink symbols: U, U, U, U, U, U, U, U, U, U, U, U. It should be understood that... Figure 8 The structure described herein is merely an example and is intended to aid in understanding this disclosure.

[0090] In the first (uplink) symbol 809 of special time slot 805, the UE performs transmission on the first AP. In the second (uplink) symbol 811 of special time slot 805, the UE performs transmission on the second AP. It is assumed that the first AP and the second AP are different. In this way, Figure 8 In one example, the transmission on the first AP and the transmission on the second AP are performed on two different symbols (i.e., adjacent symbols within a time slot). These transmissions can be considered "sequential" transmissions. In other examples, the two transmissions are performed on the same (single) symbol (which can be referred to as "simultaneous").

[0091] exist Figure 8In the example, the UE measures the phase difference between the transmission in the first symbol 809 and the transmission in the second symbol 811. This phase difference is compared with the phase difference associated with the SRS transmission from the UE. It is assumed that the phase difference associated with the SRS transmission from the UE is known to the UE, for example, it can be stored by the UE as a "reference" phase difference. This will be described in more detail below.

[0092] Figure 8 The third (uplink) symbol 813 of uplink slot 807 is shown. The third symbol 813 can be used for UL physical channel transmission (e.g., UL MIMO) or can be used as a gap from scheduling. This gap 813 can be referred to as a symbol scheduling gap (SSG) or gap symbol, or similar. An SSG represents at least one symbol that is not scheduled for UL transmission but is used by the UE to perform phase reconfiguration or recalibration. In this example, the UE utilizes a symbol 813 as a gap symbol. For example, the UE can utilize the timing of this gap symbol 813 to perform reconfiguration based on a determined phase difference (i.e., the phase difference between the transmission in the first symbol 809 and the transmission in the second symbol 811, and a reference phase difference). In this way, in this example, uplink slot 807 can be considered to have the following structure: G, U, U, U, U, U, U, U, U, U, U, U, U. In some examples, the SSG used for reconfiguration / recalibration can be configured for symbols that are also used for transmission, such as symbol 809 in slot 805. In this way, the UE is able to perform reconfiguration and recalibration in a single symbol at the beginning of the UL symbol sequence.

[0093] The NW is aware that the UE should not be scheduled to perform uplink transmissions in the first symbol 809 and the second symbol 811 because the UE has previously indicated this to the NW. In some examples, the UE will also indicate that the third symbol 813 should not be used for scheduled UL transmissions either, as the UE will use this symbol as a gap symbol.

[0094] Following the gap in the third symbol 813, UL transmissions from UL (e.g., UL MIMO transmissions) are considered coherent. This is because any phase difference caused by the UE switching from UL to DL and then back to UL has been determined and subsequently compensated.

[0095] It should be understood that the positions of the two (or more) symbols used for phase adjustment (e.g., 809 and 811) can be located anywhere within the time slot. For efficiency, these two symbols are located at the beginning of the sequence of assigned UL symbols.

[0096] exist Figure 8In the example, a total of three (adjacent) symbols are used to determine the phase difference by performing transmissions (809, 811) on the first and second APs and subsequently using the third symbol 813. In other examples, a single symbol (e.g., 809) is used instead of three symbols (e.g., ...). Figure 8 (e.g., 809, 811, 813). In such an example, transmissions on the first AP and the second AP are performed within a single symbol (e.g., 809). Phase determination and reconfiguration / recalibration are also performed within this single symbol (e.g., 809).

[0097] As described above, the UE measures and compensates for the phase difference for two or more APs during UL transmission. This can be referred to as UL Coherence with Symbol Delay (SD-C) UL MIMO transmission mode. It should be understood that this name is given only as an example, and any suitable name can be given to this process. As part of SD-C, the UE can indicate to the NW (e.g., gNB): at least one symbol allocated in the UL time slot (in Figure 8 (In the example, there are 3 symbols) After that, the UE's transmission to UL will be coherent. This is in Figure 8 This is illustrated by symbol 815, where the arrow indicates a coherent transmission immediately following the third symbol 813. For example, the NW can anticipate that the UE, which has already indicated to the NW for SD-C UL transmissions, is targeting the first "N" symbols (e.g., in...). Figure 8 In the example, N=3 symbols) will be incoherent, where the UL transmissions during the first “N” symbols will be configured for a single, different AP (rather than multiple different APs). The number of symbols N can vary as a function of the UL MIMO rank used by the UE. The number of symbols N can depend on the number of APs to be calibrated. For example, if more APs are to be calibrated by the UE, it may take longer (e.g., N can be larger). The number of symbols N can depend on at least one of the following: PA power level, the allocated frequency bandwidth of the PUCCH / PUSCH transmission, and / or the number of APs to be calibrated.

[0098] As mentioned above, in Figure 8 In one example, the UE utilizes one SSG (or gap symbol) 813 to be used for reconfiguration / recalibration. In other examples, the UE may utilize multiple SSGs. In still other examples, some UEs may not require any SSGs.

[0099] In some examples, the UE transmits an indication (or request) for an SSG to the NW. This request may include indications about when an SSG is needed and its required duration (e.g., how many symbols). In some examples, the UE does not request an SSG. The UE also indicates to the NW the symbols needed for phase measurement (e.g., 809, 811). The symbols used for phase measurement may be UL symbols immediately preceding the requested SSG. The number of symbols requested for phase measurement may depend on the number of FBRs implemented in the device, whether they are shared FBRs or one FBR per UL link (PA). In other examples, the UE indicates to the NW the symbols requested for phase measurement (e.g., 809, 811) without indicating an SSG. In this example, the UE avoids providing an indication / request for an SSG. For example, the UE may have sufficient processing power to perform reconfiguration / recalibration between symbols (i.e., one or more gap symbols are not required).

[0100] The UE can use any suitable method to measure the phase associated with the transmission in the first symbol 809 and the transmission in the second symbol 811. For example, the UE can use the first two symbols 809 and 811 of the UL, and use a feedback receiver (FBR) at each PA (e.g., AP) associated with the corresponding AP. Figure 7 The phase difference is measured at each output of PA 715 or PA 719 in the configuration. The FBR can already be used for PA power control and digital predistortion (DPD). The UE can measure the relative phase difference between all configurable APs during SRS transmission and subsequently remeasure the phase after the Tx link used for PUSCH is powered on (e.g., in the first symbol 809 and subsequently the second symbol 811). Because the UE knows the relative phase difference between the configured APs measured during SRS transmission, the UE can adjust the relative phase difference between the configured APs for subsequent PUSCH / PUCCH transmissions while achieving UL MIMO coherence compliance.

[0101] The duration of the phase adjustment process depends on the UE implementation (e.g., I / Q or PLL phase adjustment, which will be discussed below). Figure 10(To be discussed in more detail). In some examples, the UE uses an SSG or gap symbol because the phase difference between two or more APs is unknown to the UE at the start of the SSG. When the phase difference is unknown to the UE at the start of the SSG, this means the validity of the applied precoding is also unknown. Furthermore, the phase difference between two or more APs may change during the duration of the SSG. However, at the end of one or more SSGs, the precoding (e.g., determined from the received TPMI) will be correct because the UE has already performed its phase adjustment process. Therefore, the UE may not be able to transmit meaningful data during the SSG because the UE is adjusting the phase difference between one or more AP pairs by changing the phase on one AP in each pair. In other words, for multi-AP (i.e., at least two APs) MIMO transmission, each MIMO layer of the MIMO transmission is distributed to multiple APs, and the relative phase between APs in the MIMO layer is adjusted based on the determined phase difference (relative to the SRS transmission) and the TPMI. Phase adjustment of the APs may include time delay of the precoding of the MIMO layer (e.g., time delay of at least one symbol). This will be discussed in conjunction with the following. Figure 9 The signaling and operation diagrams will be described in more detail.

[0102] Figure 9 Example signaling and operation diagrams for user equipment and base stations used for coherent UL transmission with symbol delay are shown.

[0103] In S901, the UE is in Radio Resource Control (RRC) connection state and connected to the gNB.

[0104] In S902, the UE transmits the following indication to the gNB: The UE supports coherent transmission with symbol-delayed (SD). In some examples, this indication is provided in the capability report (or similar). This indication may specify a fixed number of symbols used for the SD procedure. The UE may indicate a (fixed) number of symbols for each supported UL MIMO rank.

[0105] In S903, the gNB initiates coherent UL transmission for UL. UL transmission can be UL MIMO transmission.

[0106] In S904, the gNB transmits to the UE the resource allocation (i.e., resource allocation) for SRS transmission.

[0107] In S905, the UE performs the first SRS transmission on its first AP. The UE performs the second SRS transmission on its second AP. The UE's first AP and second AP are different from each other.

[0108] The first and second transmissions are based on resource allocation for SRS.

[0109] In S906, the UE determines (or measures) the phase associated with the first transmission. The UE determines (or measures) the phase associated with the second transmission. The UE determines a first phase difference between the phase associated with the first transmission and the phase associated with the second transmission.

[0110] The UE stores the first phase difference locally to use as a reference for upcoming PUSCH transmissions.

[0111] In S907, the gNB receives a first transmission and a second transmission from the UE. Based on the first and second transmissions, the gNB selects a TPMI from multiple TPMI options (e.g., from...). Figure 5 (One of the TPMI indexes in the index).

[0112] In S908, the UE transmits an indication of the number of symbols to the gNB. This number of symbols can be used by the UE to perform phase determination or phase adjustment. The UE can indicate at least one symbol. In some examples, the UE can indicate two symbols. These two symbols can be used by the UE to perform transmissions to determine another phase difference (e.g., see S912 to S914). In some examples, the UE can indicate three symbols. Two of the three symbols can be used by the UE to perform transmissions to determine another phase difference (e.g., see S912 to S914), and the third symbol can be used by the UE for recalibration (after phase difference determination). The symbol used for recalibration can be referred to as the symbol scheduling gap (SSG). An example frame structure for symbols used to perform phase determination or phase adjustment is shown in [the image / frame]. Figure 8 As shown in the image.

[0113] In S909, the UE performs a transmit (Tx) to receive (Rx) reconfiguration. In other words, the UE reconfigures its transceiver and RF front end from UL to DL.

[0114] In S910, the gNB transmits the TPMI and resource allocation for physical channel transmission (i.e., resource allocation) to the UE. For example, resource allocation can be used for the physical uplink shared channel or the physical uplink control channel. For example, the TPMI can be provided via downlink control information (DCI) (e.g., as implemented for 5G).

[0115] In S911, the UE performs an Rx to Tx reconfiguration. In other words, the UE reconfigures its transceiver and RF front end from DL to UL.

[0116] In S912, the UE performs a third transmission on the first symbol of the first AP. The third transmission can be a physical channel transmission (e.g., PUSCH). When performing the third transmission, the UE determines (or measures) the phase associated with it. For example, the UE can measure this phase at the output of each PA connected to the first AP. In other examples, any other suitable method for measuring / determining the phase can be used.

[0117] In S913, the UE performs a fourth transmission on the second symbol of the second AP. The fourth transmission can be a physical channel transmission (e.g., PUSCH). When performing the fourth transmission, the UE determines (or measures) the phase associated with it. For example, the UE can measure this phase at the output of each PA connected to the second AP. In other examples, any other suitable method for measuring / determining the phase can be used.

[0118] The first and second symbols can be adjacent to each other in a time slot. For example, the first and second symbols can be the last two symbols in a time slot. Both the first and second symbols are "uplink" symbols.

[0119] In some examples, when the UE has two feedback receivers (FBRs) and is able to separate each stream by code domain correlation to perform phase difference determination, S912 and S913 can be performed by the UE simultaneously, or S912 and S913 can be extended to more than two steps depending on the number of APs.

[0120] In S914, the UE determines a second phase difference between the phase associated with the third transmission and the phase associated with the fourth transmission. The UE determines the (total) phase difference between the first phase difference and the second phase difference. In this way, the UE determines how much phase has changed between the transmission to the SRS and the transmission to the physical channel. Due to the reconfiguration in S909 and S911, the phase has likely changed.

[0121] In S915, based on the (total) phase difference, the UE performs phase-related recalibration or reconfiguration for subsequent transmissions. This is described in more detail below.

[0122] In S916, the UE performs a physical channel MIMO transmission to the gNB. This MIMO transmission is based on resource allocation and TPMI (received in S910). In some examples, the physical channel MIMO transmission includes transmitting PUSCH (or PUCCH) symbols based on TPMI (determined by the gNB).

[0123] Physical channel MIMO transmission can have a single (MIMO) layer (e.g., single-layer transmission). In other examples, physical channel MIMO transmission has multiple (MIMO) layers.

[0124] Each corresponding MIMO layer (of the physical channel MIMO transmission) is transmitted on two or more APs (of the UE). Precoding for each corresponding MIMO layer is based on TPMI. For example, the MIMO layers of the physical channel MIMO transmission are transmitted on the first AP and the second AP. In some examples, this may be referred to as multi-AP precoding of the MIMO layers.

[0125] Precoding for each corresponding MIMO layer is also based on the (total) phase difference. For example, precoding of the first MIMO layer (for at least one physical channel MIMO transmission) associated with the first AP and the second AP is based on the TPMI and the (total) phase difference. The phase shift indicated by the TPMI for the first MIMO layer is adjusted based on the (total) phase difference. In other words, the UE adjusts the phase on one AP (e.g., one of the first AP or the second AP) in each pair of APs based on the (total) phase difference.

[0126] The execution of physical channel MIMO transmission is also based on the (total) phase difference. For physical channel transmission, the precoding associated with at least two antenna ports (e.g., the first AP and the second AP) for at least one MIMO layer of physical channel MIMO transmission is delayed by at least one symbol in the sequence of allocated UL symbols in resource allocation. The delay of at least one symbol is based on the number of symbols used by the UE for phase determination and the optional SSG used by the UE. In other words, the delay of at least one symbol is based on an indication of the number of symbols (e.g., in S908). For example, for Figure 8 In the configuration shown, multi-AP precoding of at least one MIMO layer for physical channel MIMO transmission is delayed by three symbols (e.g., two symbols for transmission and one gap symbol). In some examples, at least some of the three symbols (not used for multi-AP precoding) are alternatively used for single-AP precoding MIMO transmission. In this way, based on the phase calibration time used by the UE, multi-AP precoding of at least one MIMO layer for physical channel MIMO transmission is delayed by at least one symbol in the sequence of allocated UL symbols (for resource allocation for physical channel transmission).

[0127] In this context, the "delay" in multi-AP precoding for physical channel MIMO transmissions means that multi-AP precoding transmissions are not performed in the initially available uplink symbols. In this way, the UE can perform single-AP precoding (only) before the delay in the initially available uplink symbols. Physical channel MIMO transmissions precode across multiple APs after a delay (in time / symbol). For example, the UE is allocated a sequence of UL symbols, such as in resource allocation. The "delay" means that the UE precodes the UL transmissions across multiple APs after a delay of at least one symbol relative to the allocated UL symbol sequence.

[0128] As mentioned above, the precoding across multiple APs for each corresponding MIMO layer is also based on the (total) phase difference. The following example is provided to aid in understanding this disclosure. It should be understood that the numerical values / quantities given are merely illustrative and should not be considered limiting: The first UE (UE1) has two antenna ports (first AP, AP1, and second AP, AP2): UE1 performs the first SRS Tx on AP1 -> UE1 measures a 10-degree phase for the first SRS Tx. UE1 performs the second SRS Tx on AP2 -> UE1 measures a 25-degree phase for the second SRS Tx. UE1 calculates the relative phase difference (SRS) to be 15 degrees (i.e., 25-10=15). There is a Tx-to-Rx reconfiguration for UE1 because UE1 receives TPMI from the network. Then, there is an Rx-to-Tx reconfiguration for UE1 (i.e., so that PUSCH can then be transmitted). UE1 performs the first single AP MIMO PUSCH Tx on AP1 -> UE1 measures 12 degrees of phase for the first PUSCH Tx. UE1 performs a second single AP MIMO PUSCH Tx on AP2 -> UE1 measures a 32-degree phase for the second PUSCH Tx. The relative phase difference calculated by UE1 (PUSCH) is 20 degrees (i.e., 32-12). UE1 compares the relative phase difference of (SRS) with the relative phase difference of (PUSCH) -> UE1 determines a difference of 20-15 = 5 degrees. UE1 can now perform precoding of the first MIMO layer of PUSCH MIMO Tx across multiple APs based on TPMI and a (determined) 5-degree difference. TPMI instruction: For the first MIMO layer, precoding should be performed on the first AP and the second AP, and there should be a 90-degree phase shift (between the APs). UE1 adjusts the 90-degree phase shift (from TPMI) based on a measured 5-degree difference. UE1 determines the phase shift between the first AP and the second AP to be 90 - 5 = 85 degrees. UE1 performs PUSCH MIMO Tx across multiple APs to the network. It should be understood that the numerical values ​​included in the above examples for "UE1" are merely illustrative and should not be construed as restrictive. It should also be understood that in some other examples, Figure 9 One or more steps may not be performed or may be performed in a different order.

[0129] In some examples, the UE provides the gNB with the following indication: the number of SRS resources and / or UL symbol gaps that the UE will use for calibration to achieve coherent transmission. The gNB then schedules / allocates a certain number of SRS resources and / or symbol gap resources based on this indication.

[0130] As described above Figure 9 The UE performs a phase calibration process to measure the phase difference between its APs. Since the UE's Tx link functional blocks (including PAs) may have unknown phase states after a power-on cycle, this measurement can be performed at the output of the UE's PAs. This process can be performed at the UE when the UE transmits SRS to the gNB, allowing the gNB to determine the "optimal" TPMI for PUSCH transmission. The UE can utilize one or more FBRs connected to the output of each PA via directional couplers to measure the PA output signals during SRS (e.g., S905) and / or PUSCH (e.g., S912, S913) transmissions. This allows the UE to determine the relative phase difference between two or more PAs (i.e., between two or more APs) for SRS and PUSCH transmissions. The UE then uses the phase difference between the SRS and PUSCH transmissions for phase adjustment. In some examples, the same PLL of the UE is used for both the voltage-controlled oscillator (VCO) in the Tx link and the VCO in the FBR link. The same PLL can be used so that the relative phase difference at the PA output is the same as the relative phase difference measured at the FBR after downconversion and analog-to-digital converter (ADC).

[0131] In some examples, the timing used for phase measurement (e.g., S905, S906, S912, S913) depends on the UE's capabilities. In some examples, the UE may be restricted to sequential AP measurements. In other examples, the UE is able to perform parallel measurements between active APs. The UE may have a dedicated FBR for each Tx / PA link, or the UE may have a shared (handover) FBR for multiple Tx links.

[0132] As described above Figure 9 As described above (e.g., S915), the UE performs phase adjustment at the start of MIMO transmission. This phase adjustment is based on SRS (e.g., S906) and physical channel phase measurements (e.g., S914). The UE compares the measured phase difference from the SRS transmission with the phase difference from the physical channel transmission (e.g., S906). Figure 9 The phase difference between the third and fourth transmissions in the process is compared. Any difference between the SRS phase difference and the physical channel phase difference is corrected / adjusted by the (total) phase difference determined by the data stream delay to one of the two APs. Figure 10 As shown, this correction / adjustment can be performed in the digital domain (e.g., at the I / Q level) via, for example, digital beamforming, or in the analog domain. Adjustment in the analog domain can be performed, for example, using a phase shifter, or by applying a phase shift via a PLL / VCO in one of two Tx links.

[0133] Figure 10 An example schematic representation of the radio components of a UE with two Tx / Rx links is shown. Figure 10 Schematic representation and Figure 7 The UEs shown are similar, so common elements between the two graphs are given the same label.

[0134] In the digital baseband block 701, phase adjustment can be performed at the Tx Q / I generation block 1001. The adjustment at the Tx Q / I generation block 1001 will be an adjustment in the digital domain. In the radio transceiver 703, phase adjustment can be performed at PLLs 713 and 717. The adjustment at PLLs 713 and 717 will be an adjustment in the analog domain. Adjusting the relative phase difference in the analog domain may require hardware updates / additions compared to some traditional UEs. Adjusting the relative phase difference in the digital domain can be configured solely through software or configuration updates (i.e., for digital domain processing, no hardware changes are required at the UE).

[0135] Figure 10 The following indication is also shown: for example, the location where the measurement of the relative phase difference between AP1 and AP2 for transmitting SRS and PUSCH transmissions is performed, i.e., at the outputs of PA1 715 and PA2 719, respectively. This indication is indicated by label 1003.

[0136] In this way, Figure 10 It shows the relationship with Figure 7 It is a UE similar to the UE, but with additional indications of symbol-delayed coherent transmission calibration points and symbol-delayed coherent transmission phase adjustment points.

[0137] The above examples offer the advantage that the UE can perform coherent UL transmissions to the network. Specifically, the UE can maintain the coherence of UL transmissions even after switching from a configuration for transmission to a configuration for reception and then back to transmission. Typical UE behavior involves disabling the PA, LO, and PLL of the Tx link when configured for DL, as this reduces potential self-interference and contributes to power savings at the UE. When the PLL is re-enabled, the absolute phase of the PLL will be random, and consequently, the absolute phase of the LO will also be random, thus the relative phase between any two UL APs will also be random when the UE switches from Rx to Tx. The above examples describe a UE capable of determining the phase difference between transmitting SRS from two or more APs and subsequently transmitting PUSCH / PUCCH. The UE can then compensate for potential phase differences to ensure that the transmission meets the requirements / rules for coherent UL transmissions (e.g., UL MIMO). In other words, the UE is enabled to perform relative phase calibration between two or more APs using one or more symbols in the UL timeslot after switching from Rx (or power-off) to Tx (i.e., powering on the UL link) to ensure UL coherent transmission.

[0138] Figure 11 An example method flow executed by a device is illustrated. The device can be a UE or other terminal device. The device may include components for causing the device to perform... Figure 11 The apparatus may include: at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform. Figure 11 The method.

[0139] In S1101, the method includes: performing a first transmission of a first probe reference signal (SRS) on a first antenna port (AP) and performing a second transmission of a second SRS on a second AP, wherein the first AP and the second AP are different.

[0140] In S1103, the method includes: determining a first phase difference between the first transmission and the second transmission.

[0141] In S1105, the method includes: receiving a resource allocation from a network entity for uplink physical channel transmission.

[0142] In S1107, the method includes: performing a third transmission on a first symbol at a first AP and performing a fourth transmission on a second symbol at a second AP, based on resource allocation.

[0143] In S1109, the method includes: determining a second phase difference between the third transmission and the fourth transmission.

[0144] In S1111, the method includes: performing a multiple-input multiple-output (MIMO) transmission to at least one physical channel of a network entity based on resource allocation and the difference between a first phase difference and a second phase difference, wherein precoding of at least one MIMO layer of the at least one physical channel MIMO transmission associated with at least two antenna ports is delayed by at least one symbol in the sequence of allocated UL symbols of the resource allocation.

[0145] It should be understood that in some examples, Figure 11 The method flow includes one or more additional method steps, which are executed by the device. In some examples, the above-described process... Figure 11 One or more method steps may not be executed, or may be executed in a different order.

[0146] Figure 12 An example method flow executed by a device is illustrated. The device can be a network entity (e.g., a BS, gNB, or other network node). The device may include methods for enabling the device to perform... Figure 12 The apparatus may include: at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform. Figure 12 The method.

[0147] In S1201, the method includes: receiving from a user equipment UE a first transmission of a first probe reference signal SRS on a first antenna port AP and a second transmission of a second SRS on a second AP, wherein the first AP and the second AP are different.

[0148] In S1203, the method includes: transmitting to the UE a resource allocation for uplink physical channel transmission.

[0149] In S1205, the method includes: receiving from the UE a third transmission on a first symbol on a first AP, and a fourth transmission on a second symbol on a second AP.

[0150] In S1207, the method includes: receiving at least one physical channel multiple-input multiple-output (MIMO) transmission from the UE based on resource allocation, wherein precoding of at least one MIMO layer of the at least one physical channel MIMO transmission associated with at least two antenna ports is delayed by at least one symbol in the sequence of allocated UL symbols of the resource allocation.

[0151] It should be understood that in some examples, Figure 12 The method flow includes one or more additional method steps, which are executed by the device. In some examples, the above-described process... Figure 12 One or more method steps may not be executed, or may be executed in a different order.

[0152] Figure 13 A schematic representation of the device is shown. Figure 13 A block diagram of apparatus 10 is shown by way of example. Apparatus 10 includes, for example, at least one processor 12 and at least one memory 14 storing instructions 15 that, when executed by the at least one processor, cause apparatus 10 to perform at least the methods or approaches disclosed herein and any embodiments thereof. In one example, the at least one memory and instructions (e.g., computer program code, software) together with the at least one processor are configured to cause apparatus 10 to perform the methods or approaches disclosed herein and any embodiments thereof.

[0153] Processor 12 may include, or be configured as, circuits or circuits configured to perform stages of the methods according to the exemplary embodiments described herein. The term "circuit" as used herein may refer to one or more of the following: (a) a hardware-only circuit implementation, such as an implementation in analog and / or digital circuits only; and (b) a combination of hardware circuitry and software, for example, as appropriate: (i) a combination of analog and / or digital hardware circuitry and software / firmware; and (ii) any portion of a hardware processor that works with software (including digital signal processors), software, and memory to enable a device (e.g., a user equipment) to perform various functions; and (c) hardware circuitry and / or a processor, such as a microprocessor or a portion thereof, which requires software (e.g., firmware) to operate, but which may be absent when operation is not required. This definition of "circuit" applies to all uses of the term herein, including its use in any claim. As a further example, the term "circuit" as used herein also encompasses implementations of hardware circuitry or processors (or processors) only, or portions thereof, and their accompanying software and / or firmware. The term "circuit" also covers, for example and if applicable to certain claim elements, baseband integrated circuits or processor integrated circuits for mobile devices, or similar integrated circuits in servers, cellular network devices or other computing or networking devices.

[0154] The memory 14 can be implemented using any suitable data storage technology. The memory may include a database for storing data. The memory 14 may be at least partially located outside the device 10, but is accessible to the device 10.

[0155] Instruction 15 may be included in a computer-readable medium or a non-transitory computer-readable medium. The term “non-transitory” is used herein as a limitation on the medium itself (i.e., tangible, not semaphore), rather than a limitation on the persistence of data storage (e.g., random access memory RAM compared to read-only memory ROM).

[0156] For example, device 10 is a terminal device, such as Figure 8 or Figure 9 The device is included in such a UE, for example, as a chipset configured to control the UE. Device 10 can be made or configured to perform at least... Figure 11 The methods and / or any one or more examples described.

[0157] As another example, device 10 is a network node or network entity, such as Figure 9The device is included in such a network entity (gNB). In another example, the device is included in such a network entity, for example, as a chipset configured to control the network entity. The device 10 can be made or configured to perform at least Figure 12 The methods and / or any one or more examples described.

[0158] Device 10 includes a wireless interface 16. The wireless interface 16 can provide communication capabilities to device 10. The wireless interface 16 may include a receiver configured to receive information according to at least one cellular or non-cellular standard. The wireless interface 16 may include a transmitter configured to transmit information according to at least one cellular or non-cellular standard. The receiver may include multiple receivers. The transmitter may include multiple transmitters. The wireless interface 16 may include a transceiver configured to receive and transmit information according to at least one cellular or non-cellular standard. The transceiver may include multiple transceivers.

[0159] Device 10 may include a user interface 18, such as at least one of a keyboard, microphone, touch display, monitor, speaker, etc. The user interface 18 can be used by a user to control the device. The user interface 18 may be located outside of device 10. For example, device 10 may be connected to another device (e.g., a computer) via a wireless or wired connection, and the user may control device 10 through that computer.

[0160] In one embodiment, at least some of the processes described herein may be performed by means including components for performing at least some of the described processes. Components for performing the method steps disclosed herein may include software and / or hardware components of the means 10. For example, the at least one processor 12, memory 14, and computer program code form components for performing the methods or approaches disclosed herein and any embodiments thereof. In this document, the term “component” should be interpreted as either singular (i.e., a single element) or plural (i.e., a combination of multiple elements). Therefore, the term “component for performing [A, B, C]” should be interpreted to encompass means in which only one component for performing A, B, and C is present, or components for performing A, B, and C are present respectively, or components for performing A, B, and C are present in partially or completely overlapping manner. Furthermore, the terms "component for performing A, component for performing B, component for performing C" should be interpreted to encompass the following arrangements: where only one component exists for performing A, B, and C; where components exist for performing A, B, and C respectively; or where components for performing A, B, and C partially or completely overlap. It should be noted that although exemplary embodiments have been described above, several variations and modifications can be made to the disclosed solutions without departing from the scope of the invention.

[0161] Therefore, these examples can vary within the scope of the appended claims. Generally, some embodiments can be implemented in hardware or dedicated circuitry, software, logic, or any combination thereof. For example, some aspects can be implemented in hardware, while others can be implemented in firmware or software, which can be executed by a controller, microprocessor, or other computing device, although the embodiments are not limited thereto. While various embodiments may be shown and described as block diagrams, flowcharts, or using other illustrated representations, it should be understood that the modules, apparatus, systems, techniques, or methods described herein can be implemented, for example (as a non-limiting example), in hardware, software, firmware, dedicated circuitry or logic, general-purpose hardware or controllers or other computing devices, or combinations thereof.

[0162] These examples can be implemented by computer software stored in memory and executed by at least one data processor of the relevant entity, or by hardware, or by a combination of software and hardware. Furthermore, it should be noted that any process can be represented as program steps, or interconnected logic circuits, modules, and functions, or a combination of program steps and logic circuits, modules, and functions. The software can be stored on a physical medium such as a memory chip, or in a memory block implemented within a processor, or on a magnetic medium such as a hard disk or floppy disk, or on an optical medium such as a DVD and its data variants, or a CD.

[0163] The term “non-transient” as used in this paper refers to the limitation on the medium itself (i.e., tangible, not tactile), rather than the limitation on the persistence of data storage (e.g., RAM compared to ROM).

[0164] In this document, “at least one of the following: ” and similar wording, where the list of two or more elements is connected by “and” or “or”, indicates at least any one element, or at least any two or more elements, or at least all elements.

[0165] The memory can be of any type suitable for the local technical environment and can be implemented using any suitable data storage technology, such as semiconductor-based storage devices, magnetic storage devices and systems, optical storage devices and systems, fixed memory, and removable memory. The data processor can be of any type suitable for the local technical environment and can include one or more of, for example, general-purpose computers, special-purpose computers, microprocessors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), gate-level circuits, and processors based on multi-core processor architectures (as non-limiting examples).

[0166] Alternatively or additionally, some examples can be implemented using circuitry. This circuitry can be configured to perform one or more of the previously described functional and / or methodological steps. This circuitry can be located in a base station and / or communication equipment.

[0167] As used in this application, the term "circuit" may refer to one or more or all of the following: (a) implemented solely by hardware circuitry (e.g., implemented with purely analog and / or digital circuitry); (b) a combination of hardware circuitry and software, such as: (i) a combination of (multiple) analog and / or digital hardware circuitry and software / firmware; and (ii) any part of a hardware processor having software (including (multiple) digital signal processors, software, and (multiple) memories, which work together to enable a device (e.g., a communication device or base station) to perform the various functions previously described); and (c) (multiple) hardware circuitry and / or (multiple) processors that require software (e.g., firmware) for operation, such as (multiple) microprocessors or parts thereof, but where the software may be absent when operation does not require it.

[0168] This definition of "circuit" applies to the use of the term (component) in this application (including the claims). As a further example, as used in this application, the term "circuit" also covers only hardware circuitry or a processor (or multiple processors), or portions of hardware circuitry or a server and their accompanying software and / or firmware implementations. For example, where applicable to a particular claim element, the term "circuit" also covers, for example, integrated devices. The term "circuit" also covers baseband integrated circuits or processor integrated circuits for mobile devices or similar integrated circuits in servers, cellular network devices, or other computing or networking devices.

[0169] The foregoing description provides a complete and informative description of some embodiments through exemplary and non-limiting examples. However, various modifications and alterations will be apparent to those skilled in the art when reading the foregoing description in conjunction with the accompanying drawings and appended claims. Nevertheless, all such and similar modifications will still fall within the scope defined by the appended claims.

[0170] Furthermore, the various implementations of this disclosure can be described with reference to the following examples, and their features can be combined in any reasonable manner.

[0171] Example 1. A method for wireless communication performed by a user equipment (UE), the method comprising: performing a first transmission of a first sounding reference signal (SRS) on a first antenna port (AP) and a second transmission of a second SRS on a second AP, wherein the first AP and the second AP are different; determining a first phase difference between the first transmission and the second transmission; receiving a resource allocation for uplink physical channel transmission from a network entity; performing a third transmission on a first symbol on the first AP and a fourth transmission on a second symbol on the second AP based on the resource allocation; determining a second phase difference between the third transmission and the fourth transmission; and performing a multiple-input multiple-output (MIMO) transmission to at least one physical channel of the network entity based on the resource allocation and the difference between the first phase difference and the second phase difference, wherein precoding of at least one MIMO layer of the at least one physical channel MIMO transmission associated with at least two antenna ports is delayed by at least one symbol in the sequence of allocated UL symbols of the resource allocation.

[0172] Example 2. The method according to Example 1, wherein one of the following is true: the first symbol and the second symbol are identical, the first symbol and the second symbol are adjacent symbols within a time slot, or the first symbol and the second symbol are adjacent symbols across two adjacent time slots.

[0173] Example 3. The method according to Example 1 or Example 2, wherein the method further comprises: precoding the at least two antenna ports associated with the at least one MIMO layer of the at least one physical channel MIMO transmission based on the difference between the first phase difference and the second phase difference.

[0174] Example 4. The method according to any one of Examples 1 to 3, wherein the method further comprises: transmitting to the network entity an indication of the at least one symbol, wherein the at least one symbol is used for phase adjustment for MIMO transmission of the at least one physical channel.

[0175] Example 5. According to the method of Example 4, the indication of the at least one symbol includes one of the following: an indication of one symbol; an indication of two symbols, wherein the two symbols are the last two symbols in a time slot of a frame; or an indication of three symbols, wherein two of the three symbols are the last two symbols in a time slot of a frame, and one of the three symbols is the first symbol in another time slot of the frame.

[0176] Example 6. According to the method of Example 4 or 5, the indication of the at least one symbol includes: a first indication of two or more symbols associated with a first UL MIMO rank supported by the UE, and a second indication of two or more symbols associated with a second UL MIMO rank supported by the UE.

[0177] Example 7. The method according to any one of Examples 1 to 6, wherein the method further comprises: receiving a Transport Precoding Matrix Indicator (TPMI) from the network entity, wherein the execution of the at least one physical channel MIMO transmission is also based on the TPMI.

[0178] Example 8. The method according to Example 7, wherein for the precoding, the phase difference between the at least two antenna ports is based on: the TPMI, and the difference between the first phase difference and the second phase difference.

[0179] Example 9. The method according to Example 5, wherein the execution of the at least one physical channel MIMO transmission comprises: based on the indication of the at least one symbol, delaying the precoding of the at least one MIMO layer associated with the at least two antenna ports for the MIMO transmission in the sequence by the at least one symbol.

[0180] Example 10. The method according to any one of Examples 1 to 9, wherein the method further comprises: measuring a phase for the third transmission; measuring a phase for the fourth transmission, wherein the second phase difference between the third transmission and the fourth transmission is based on: a comparison between the phase for the third transmission and the phase for the fourth transmission; and determining the difference between the first phase difference and the second phase difference.

[0181] Example 11. The method according to Example 10, wherein the phase for the third transmission is measured at the output of a first power amplifier of the UE associated with the third transmission, and wherein the phase for the fourth transmission is measured at the output of a second power amplifier of the UE associated with the fourth transmission.

[0182] Example 12. The method according to any one of Examples 1 to 11, wherein the method further comprises: transmitting to the network entity an indication that the UE supports symbol-delayed coherent UL transmission.

[0183] Example 13. According to the method of Example 12, wherein the indication that the UE supports symbol-delayed coherent UL transmission is transmitted together with the indication of the at least one symbol.

[0184] Example 14. The method according to any one of Examples 1 to 13, wherein the third transmission and the fourth transmission are one of the following: physical uplink shared channel transmission or physical uplink control channel transmission.

[0185] Example 15. The method according to any one of Examples 1 to 14, wherein the determination of the first phase difference comprises: measuring the phase for the first transmission; measuring the phase for the second transmission; and comparing the phase for the first transmission with the phase for the second transmission to determine the first phase difference.

[0186] Example 16. A method for wireless communication performed by a network entity, the method comprising: receiving from a user equipment (UE) a first transmission of a first sounding reference signal (SRS) on a first antenna port (AP) and a second transmission of a second SRS on a second AP, wherein the first AP and the second AP are different; transmitting to the UE a resource allocation for uplink physical channel transmission; receiving from the UE a third transmission on the first AP on a first symbol and a fourth transmission on the second AP on a second symbol; and, based on the resource allocation, receiving from the UE at least one physical channel multiple-input multiple-output (MIMO) transmission, wherein precoding of at least one MIMO layer of the at least one physical channel MIMO transmission associated with at least two antenna ports is delayed by at least one symbol in the sequence of allocated UL symbols of the resource allocation.

[0187] Example 17. The method according to Example 16, wherein the method further comprises: receiving from the UE an indication of the at least one symbol, wherein the at least one symbol is used for phase adjustment for the at least one physical channel MIMO transmission; and determining the resource allocation based on the indication of the at least one symbol.

[0188] Example 18. According to the method of Example 17, the indication of the at least one symbol includes one of the following: an indication of one symbol; an indication of two symbols, wherein the two symbols are the last two symbols in a time slot of a frame; or an indication of three symbols, wherein two of the three symbols are the last two symbols in a time slot of a frame, and one of the three symbols is the first symbol in another time slot of the frame.

[0189] Example 19. The method according to any one of Examples 16 to 18, wherein the method further comprises: determining a Transport Precoding Matrix Indicator (TPMI) based on the first transmission and the second transmission received from the UE; and transmitting the TPMI to the UE.

[0190] Example 20. The method according to any one of Examples 16 to 19, wherein the method further comprises: receiving from the UE an indication that the UE supports symbol-delayed coherent UL transmission; initiating coherent uplink MIMO transmission for the UE based on the indication; and transmitting to the UE an SRS resource allocation for SRS transmission.

[0191] Example 21. The method according to any one of Examples 16 to 20, wherein the physical channel MIMO transmission is one of the following: physical uplink shared channel transmission, or physical uplink control channel transmission.

[0192] Example 22. A user equipment (UE) for wireless communication includes: at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to at least: perform a first transmission of a first sounding reference signal (SRS) on a first antenna port (AP) and a second transmission of a second SRS on a second AP, wherein the first AP and the second AP are different; determine a first phase difference between the first transmission and the second transmission; receive a resource allocation from a network entity for uplink physical channel transmission; based on the resource allocation, perform a third transmission on a first symbol on the first AP and a fourth transmission on a second symbol on the second AP; determine a second phase difference between the third transmission and the fourth transmission; and based on the resource allocation and the difference between the first phase difference and the second phase difference, perform a multiple-input multiple-output (MIMO) transmission to at least one physical channel of the network entity, wherein precoding of at least one MIMO layer associated with at least two antenna ports for the at least one physical channel MIMO transmission is delayed by at least one symbol in the sequence of allocated UL symbols of the resource allocation.

[0193] Example 23. The user equipment according to Example 22, wherein one of the following is true: the first symbol and the second symbol are identical, the first symbol and the second symbol are adjacent symbols within a time slot, or the first symbol and the second symbol are adjacent symbols across two adjacent time slots.

[0194] Example 24. A user equipment according to Example 22 or 23, wherein the UE is further configured to perform: precoding of at least two antenna ports associated with the at least one MIMO layer of the at least one physical channel MIMO transmission based on the difference between the first phase difference and the second phase difference.

[0195] Example 25. A user equipment according to any one of Examples 22 to 24, wherein the UE is further caused to perform: transmit an instruction to the network entity for the at least one symbol, wherein the at least one symbol is used for phase adjustment for the at least one physical channel MIMO transmission.

[0196] Example 26. The user equipment according to Example 25, wherein the indication of the at least one symbol includes one of the following: an indication of one symbol; an indication of two symbols, wherein the two symbols are the last two symbols in a time slot of a frame; or an indication of three symbols, wherein two of the three symbols are the last two symbols in a time slot of a frame, and one of the three symbols is the first symbol in another time slot of the frame.

[0197] Example 27. A user equipment according to Example 25 or 26, wherein the indication of the at least one symbol includes: a first indication of two or more symbols associated with a first UL MIMO rank supported by the UE, and a second indication of two or more symbols associated with a second UL MIMO rank supported by the UE.

[0198] Example 28. A user equipment according to any one of Examples 22 to 27, wherein the UE is further caused to perform: receive a Transport Precoding Matrix Indicator (TPMI) from the network entity, wherein the performance of the at least one physical channel MIMO transmission is also based on the TPMI.

[0199] Example 29. The user equipment according to Example 28, wherein for the precoding, the phase difference between the at least two antenna ports is based on: the TPMI, and the difference between the first phase difference and the second phase difference.

[0200] Example 30. A user equipment according to Example 26, wherein the execution of the at least one physical channel MIMO transmission includes: based on the indication of the at least one symbol, delaying the precoding of the at least one MIMO layer associated with the at least two antenna ports for the MIMO transmission in the sequence by the at least one symbol.

[0201] Example 31. A user equipment according to any one of Examples 22 to 30, wherein the UE is further configured to perform: measuring a phase for the third transmission; measuring a phase for the fourth transmission, wherein the second phase difference between the third transmission and the fourth transmission is based on: a comparison between the phase for the third transmission and the phase for the fourth transmission; and determining the difference between the first phase difference and the second phase difference.

[0202] Example 32. A user equipment according to Example 31, wherein the phase for the third transmission is measured at the output of a first power amplifier of the UE associated with the third transmission, and wherein the phase for the fourth transmission is measured at the output of a second power amplifier of the UE associated with the fourth transmission.

[0203] Example 33. A user equipment according to any one of Examples 22 to 32, wherein the UE is further caused to perform: transmit to the network entity an indication that the UE supports symbol-delayed coherent UL transmission.

[0204] Example 34. The user equipment according to Example 33, wherein the indication that the UE supports symbol-delayed coherent UL transmission is transmitted together with the indication of the at least one symbol.

[0205] Example 35. A user equipment according to any one of Examples 22 to 34, wherein the third transmission and the fourth transmission are one of the following: physical uplink shared channel transmission or physical uplink control channel transmission.

[0206] Example 36. A user equipment according to any one of Examples 22 to 35, wherein the determination of the first phase difference comprises: measuring a phase for the first transmission; measuring a phase for the second transmission; and comparing the phase for the first transmission with the phase for the second transmission to determine the first phase difference.

[0207] Example 37. A network entity for wireless communication, comprising: at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the network entity to perform at least: receiving from a user equipment (UE) a first transmission of a first sounding reference signal (SRS) on a first antenna port (AP) and a second transmission of a second SRS on a second AP, wherein the first AP and the second AP are different; transmitting to the UE a resource allocation for uplink physical channel transmission; receiving from the UE a third transmission on a first symbol on the first AP and a fourth transmission on a second symbol on the second AP; and, based on the resource allocation, receiving from the UE at least one physical channel multiple-input multiple-output (MIMO) transmission, wherein precoding of at least one MIMO layer of the at least one physical channel MIMO transmission associated with at least two antenna ports is delayed by at least one symbol in the sequence of allocated UL symbols of the resource allocation.

[0208] Example 38. A network entity according to Example 37, wherein the network entity is further configured to: receive an indication from the UE of the at least one symbol, wherein the at least one symbol is used for phase adjustment for MIMO transmission of the at least one physical channel; and determine the resource allocation based on the indication of the at least one symbol.

[0209] Example 39. A network entity according to Example 38, wherein the indication of the at least one symbol includes one of the following: an indication of one symbol; an indication of two symbols, wherein the two symbols are the last two symbols in a time slot of a frame; or an indication of three symbols, wherein two of the three symbols are the last two symbols in a time slot of a frame, and one of the three symbols is the first symbol in another time slot of the frame.

[0210] Example 40. A network entity according to any one of Examples 37 to 39, wherein the network entity is further caused to: determine a Transport Precoding Matrix Indicator (TPMI) based on the first transmission and the second transmission received from the UE; and transmit the TPMI to the UE.

[0211] Example 41. A network entity according to any one of Examples 37 to 40, wherein the network entity is further caused to perform: receiving from the UE an indication that the UE supports symbol-delayed coherent UL transmission; initiating coherent uplink MIMO transmission for the UE based on the indication; and transmitting SRS resource allocation to the UE for SRS transmission.

[0212] Example 42. A network entity according to any one of Examples 37 to 41, wherein the physical channel MIMO transmission is one of the following: physical uplink shared channel transmission or physical uplink control channel transmission.

[0213] Example 43. A network entity according to any one of Examples 37 to 42, wherein the network entity is a base station.

[0214] Example 44. A user equipment for wireless communication, comprising: means for causing the user equipment to perform at least the following: performing a first transmission of a first sounding reference signal (SRS) on a first antenna port (AP) and a second transmission of a second SRS on a second AP, wherein the first AP and the second AP are different; determining a first phase difference between the first transmission and the second transmission; receiving a resource allocation from a network entity for uplink physical channel transmission; performing a third transmission on a first symbol on the first AP and a fourth transmission on a second symbol on the second AP based on the resource allocation; determining a second phase difference between the third transmission and the fourth transmission; and performing a multiple-input multiple-output (MIMO) transmission to at least one physical channel of the network entity based on the resource allocation and the difference between the first phase difference and the second phase difference, wherein precoding of at least one MIMO layer of the at least one physical channel MIMO transmission associated with at least two antenna ports is delayed by at least one symbol in a sequence of allocated UL symbols of the resource allocation.

[0215] Example 45. A network entity for wireless communication, comprising: components for causing the network entity to perform at least the following: receiving from a user equipment (UE) a first transmission of a first sounding reference signal (SRS) on a first antenna port (AP) and a second transmission of a second SRS on a second AP, wherein the first AP and the second AP are different; transmitting to the UE a resource allocation for uplink physical channel transmission; receiving from the UE a third transmission on a first symbol on the first AP and a fourth transmission on a second symbol on the second AP; and receiving from the UE, based on the resource allocation, at least one physical channel multiple-input multiple-output (MIMO) transmission, wherein precoding of at least one MIMO layer of the at least one physical channel MIMO transmission associated with at least two antenna ports is delayed by at least one symbol in the sequence of allocated UL symbols of the resource allocation.

[0216] Example 46. A computer program comprising instructions, which, when executed by a user equipment, cause the user equipment to perform at least: performing a first transmission of a first sounding reference signal (SRS) on a first antenna port (AP) and a second transmission of a second SRS on a second AP, wherein the first AP and the second AP are different; determining a first phase difference between the first transmission and the second transmission; receiving a resource allocation from a network entity for uplink physical channel transmission; based on the resource allocation, performing a third transmission on a first symbol on the first AP and a fourth transmission on a second symbol on the second AP; determining a second phase difference between the third transmission and the fourth transmission; and based on the resource allocation and the difference between the first phase difference and the second phase difference, performing a multiple-input multiple-output (MIMO) transmission to at least one physical channel of the network entity, wherein precoding of at least one MIMO layer of the at least one physical channel MIMO transmission associated with at least two antenna ports is delayed by at least one symbol in the sequence of allocated UL symbols of the resource allocation.

[0217] Example 47. A computer program comprising instructions that, when executed by a network entity, cause the network entity to perform at least: receiving from a user equipment (UE) a first transmission of a first sounding reference signal (SRS) on a first antenna port (AP) and a second transmission of a second SRS on a second AP, wherein the first AP and the second AP are different; transmitting to the UE a resource allocation for uplink physical channel transmission; receiving from the UE a third transmission on a first symbol on the first AP and a fourth transmission on a second symbol on the second AP; and, based on the resource allocation, receiving from the UE at least one physical channel multiple-input multiple-output (MIMO) transmission, wherein precoding of at least one MIMO layer of the at least one physical channel MIMO transmission associated with at least two antenna ports is delayed by at least one symbol in the sequence of allocated UL symbols of the resource allocation.

Claims

1. A user equipment (UE) for wireless communication, comprising: At least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to perform at least the following: A first transmission of a first sounding reference signal (SRS) is performed on a first antenna port (AP), and a second transmission of a second SRS is performed on a second AP, wherein the first AP and the second AP are different. Determine the first phase difference between the first transmission and the second transmission; Receive resource allocations from network entities for uplink physical channel transmission; Based on the resource allocation, a third transmission is performed on the first AP on the first symbol, and a fourth transmission is performed on the second AP on the second symbol; Determine the second phase difference between the third transmission and the fourth transmission; as well as Based on the resource allocation and the difference between the first phase difference and the second phase difference, a multiple-input multiple-output (MIMO) transmission to at least one physical channel of the network entity is performed, wherein the precoding of at least one MIMO layer of the at least one physical channel MIMO transmission associated with at least two antenna ports is delayed by at least one symbol in the sequence of allocated UL symbols of the resource allocation.

2. The user equipment according to claim 1, wherein one of the following is true: the first symbol and the second symbol are identical, the first symbol and the second symbol are adjacent symbols within a time slot, or the first symbol and the second symbol are adjacent symbols spanning two adjacent time slots.

3. The user equipment according to claim 1, wherein the UE is further caused to perform: Based on the difference between the first phase difference and the second phase difference, the at least two antenna ports associated with the at least one MIMO layer of the at least one physical channel MIMO transmission are precoded.

4. The user equipment according to claim 1, wherein the UE is further caused to perform: Instructions for transmitting at least one symbol to the network entity, wherein the at least one symbol is used for phase adjustment for MIMO transmission of the at least one physical channel.

5. The user equipment according to claim 4, wherein the indication of the at least one symbol includes one of the following: An indication of a symbol; The indication of two symbols, wherein the two symbols are the last two symbols in a time slot of a frame, or The three symbols indicate that two of the three symbols are the last two symbols in one time slot of the frame, and one of the three symbols is the first symbol in another time slot of the frame.

6. The user equipment of claim 4, wherein the indication of the at least one symbol comprises: A first indication of two or more symbols associated with a first UL MIMO rank supported by the UE, and a second indication of two or more symbols associated with a second UL MIMO rank supported by the UE.

7. The user equipment of claim 1, wherein the UE is further caused to perform: The Transport Precoding Matrix Indicator (TPMI) is received from the network entity, wherein the execution of the at least one physical channel MIMO transmission is also based on the TPMI.

8. The user equipment of claim 7, wherein, for the precoding, the phase difference between the at least two antenna ports is based on: the TPMI, and the difference between the first phase difference and the second phase difference.

9. The user equipment of claim 5, wherein the execution of the at least one physical channel MIMO transmission comprises: Based on the indication of the at least one symbol, the precoding of the at least one MIMO layer associated with the at least two antenna ports for the MIMO transmission in the sequence is delayed by the at least one symbol.

10. The user equipment of claim 1, wherein the UE is further caused to perform: Measure the phase for the third transmission; Measure the phase for the fourth transmission. The second phase difference between the third transmission and the fourth transmission is based on a comparison between the phase for the third transmission and the phase for the fourth transmission; and Determine the difference between the first phase difference and the second phase difference.

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