Transmission system of base station, wireless terminal, distributed unit of base station, and methods for these

Abstract

This baseband unit of a base station transmits a first demodulation reference signal, which is used for demodulating modulated symbols that were generated from a broadcast channel payload, from each of a plurality of transmission points and in a separate first time period and frequency resource set for each transmission point. The baseband unit also transmits the modulated symbols that were generated from the broadcast channel payload, from each of the plurality of transmission points and in the same second time period and frequency resource set. The present invention can contribute, for example, to mitigating the difficulty of using a wireless terminal to measure the reception power or the reception quality of each beam, while suppressing an increase in the overhead of beam sweep transmissions.

Description

Base station transmission system, wireless terminal, base station distributed unit, and methods thereof

[0001] The present disclosure relates to wireless communication systems, and more particularly to beam-sweeping transmission of broadcast signals by base stations.

[0002] The 3rd Generation Partnership Project (3GPP®) Fifth Generation (5G) system uses beam sweeping to enable User Equipment (UE) to select the best beam during initial access. Specifically, a gNB transmits multiple Synchronization Signal (SS) / Physical Broadcast Channel (PBCH) blocks (SSBs) as bursts with a fixed periodicity, changing the beam direction for each SSB transmission. One SSB includes a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS), a PBCH, and a PBCH Demodulation Reference Signal (DMRS).

[0003] An SSB spans four consecutive Orthogonal Frequency Division Multiplexing (OFDM) symbols in the time domain and 240 consecutive subcarriers (i.e., 20 resource blocks) in the frequency domain. Each SSB in a burst corresponds to a separate beam and is beamformed in a different direction. A set of SSBs in a burst is called an SSB burst set and is transmitted in a half-radio frame, i.e., a 5 millisecond (ms) window. An SSB burst set (i.e., 5 ms duration) typically repeats every two radio frames, i.e., 20 ms. The maximum number of SSBs in an SSB burst set (i.e., 5 ms duration) is specified as four for frequency bands up to 3 GHz, eight for 3-6 GHz, and 64 for 6-52.6 GHz to achieve a trade-off between coverage and resource overhead. Note that the number of SSBs actually transmitted within a cell is configurable and may be less than the maximum number.

[0004] Each SSB within an SSB burst set (5 ms) is assigned an SSB index, which is a unique number starting from 0 and incrementing by 1. As the maximum number of candidate SSBs that can be transmitted within an SSB burst set is 64, the SSB index is signaled to the UE via two parts within the SSB. The SSB index is split into two fields, the first field is carried as part of the PBCH payload, and the second part of the SSB index is carried as part of the PBCH DMRS sequence.

[0005] When synchronizing to the radio access network and performing initial access, the UE needs to retrieve the SSB. In idle mode, i.e., Radio Resource Control (RRC)_IDLE or RRC_INACTIVE, the UE searches for SSBs transmitted within the cell, receives a set of SSB bursts, and selects the SSB with the best reception quality, i.e., the best beam. The SSB index is mapped to available Random Access Channel (RACH) opportunities. The UE informs the network, i.e., the gNB, of the SSB beam it has selected by transmitting a Physical RACH (PRACH) preamble on the RACH opportunity associated with the selected best beam.

[0006] The 5G specifications by 3GPP regarding the above-mentioned SSB beam sweep are provided, for example, in non-patent documents 1-4.

[0007] 3GPP TS 38.211 V17.2.0 (2022-06), "3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NR; Physical channels and modulation (Release 17)", June 2022 3GPP TS 38.212 V17.2.0 (2022-06), "3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NR; Multiplexing and channel coding (Release 17)", June 2022 3GPP TS 38.213 V17.2.0 (2022-06), "3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NR; Physical layer procedures for control (Release 17)", June 2022 3GPP TS 38.331 V17.1.0 (2022-06), "3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NR; Radio Resource Control (RRC) protocol specification (Release 17)", July 2022

[0008] The inventors anticipate that an extension of the 5G system or a future 6G or beyond system will use millimeter-wave or sub-terahertz frequencies and utilize geographically distributed Transmission Reception Points (TRPs) with overlapping coverage areas to achieve site diversity. Each TRP hosts one or more antenna elements (typically array antennas) and radio frequency (RF) components and can communicate with UEs using beams. A TRP may also be referred to as a Radio Unit (RU), Remote Radio Head (RRH), access point, or distributed antenna. When focusing only on downlink transmissions (e.g., SSB transmissions) by a base station, a TRP may also be referred to as a transmission point.

[0009] However, if multiple TRPs are used in a cell and the number of beams transmitted within the cell increases, the current maximum number of 64 candidate SSB beams may not be sufficient. If all SSB beams transmitted within a cell are swept over different time resources or OFDM symbols, the current constraints on the periodicity of the SSB burst set (i.e., 20 ms) and / or the duration of the SSB burst set (i.e., 5 ms) may need to be relaxed to increase the maximum number of candidate SSB beams beyond 64. Specifically, the periodicity of the SSB bursts may need to be shortened, the duration of the SSB burst set may need to be lengthened, or both. This would result in increased overhead for SSB transmission (i.e., beam sweeping transmission).

[0010] To address this issue, we have considered an architecture that allows multiple TRPs to simultaneously transmit SSB beams in the same time resource or OFDM symbol. This reduces the radio resources required to transmit different SSB beams and contributes to reducing the overhead of SSB transmission (i.e., beam sweep transmission). However, we have identified several challenges with this architecture. One of these challenges relates to UEs' measurement of the received power or reception quality for each SSB beam. Another of these challenges relates to UEs' identification of beams or SSBs.

[0011] In one implementation, multiple TRPs transmit different sets of PBCH modulation symbols generated from different PBCH payloads on the same time and frequency resources, or resource elements. In this implementation, depending on the UE's location, a UE may simultaneously receive SSB transmissions from multiple TRPs, but the UE may be able to demodulate the PBCH of one SSB received with greater power. However, interference between SSB beams may make it difficult for the UE to measure the received power or reception quality for each SSB beam.

[0012] In another implementation, multiple TRPs transmit different sets of PBCH modulation symbols generated from the same BCH payload on the same time and frequency resources, or resource elements. In this implementation, depending on the UE's location, a UE may simultaneously receive SSB transmissions from multiple TRPs, but the UE may be able to demodulate the PBCH of one SSB received with greater power. However, even in this implementation, interference between SSB beams may make it difficult for the UE to measure the received power or reception quality of each SSB beam. Additionally, in this implementation, bits within the same PBCH payload do not provide differentiation or identification between multiple beams or SSBs transmitted from multiple TRPs on the same time and frequency resources. Therefore, additional techniques may be required to enable the UE to uniquely identify each of these multiple beams or SSBs.

[0013] In yet another implementation, multiple TRPs transmit the same PBCH modulation symbols generated from the same PBCH payload on the same time and frequency resources, i.e., resource elements. Even in this example, interference between SSB beams can make it difficult for UEs to measure the received power or reception quality for each SSB beam. Additional techniques may be required to enable UEs to uniquely identify each of the multiple beams or SSBs transmitted by multiple TRPs on the same time and frequency resources.

[0014] One of the objectives that the embodiments disclosed in this specification aim to achieve is to provide an apparatus, a method, and a program that contribute to solving at least one of the problems, including the problems described above. It should be noted that this objective is only one of the objectives that the embodiments disclosed in this specification aim to achieve. Other objectives or objectives and novel features will become apparent from the description of this specification or the accompanying drawings.

[0015] In a first aspect, a transmission system of a base station includes a plurality of transmission points and a baseband unit configured to control each of the plurality of transmission points to transmit, on a first set of time and frequency resources distinct for each transmission point, a first demodulation reference signal used to demodulate one of the same set or different sets of modulation symbols generated from the same broadcast channel payload or different broadcast channel payloads, and further configured to control the plurality of transmission points to transmit the same set of modulation symbols or the different sets of modulation symbols on a same second set of time and frequency resources.

[0016] In a second aspect, a method performed by a base station transmission system includes the steps of: (a) transmitting, from each of a plurality of transmission points, a first demodulation reference signal used to demodulate one of the same set or different sets of modulation symbols generated from the same broadcast channel payload or different broadcast channel payloads, in a first set of time and frequency resources distinct for each transmission point; and (b) transmitting the same set of modulation symbols or the different sets of modulation symbols from the plurality of transmission points in the same second set of time and frequency resources.

[0017] In a third aspect, a wireless terminal includes RF circuitry configured to communicate with a radio access network and at least one processor, the at least one processor configured to control the RF circuitry to receive, on a first set of time and frequency resources individual for each transmission point, a first demodulation reference signal used to demodulate one of the same or different sets of modulation symbols generated from the same or different broadcast channel payloads, and the at least one processor configured to control the RF circuitry to receive, on a second set of time and frequency resources common to multiple transmission points, the same or different sets of modulation symbols.

[0018] In a fourth aspect, a method performed by a wireless terminal includes the steps of: (a) receiving, on a first set of time and frequency resources separate for each transmission point, a first demodulation reference signal used to demodulate one of the same set of modulation symbols or different sets of modulation symbols generated from the same broadcast channel payload or different broadcast channel payloads; and (b) receiving, on a second set of time and frequency resources common to multiple transmission points, the same set of modulation symbols or the different sets of modulation symbols.

[0019] In a fifth aspect, a wireless terminal includes RF circuitry configured to communicate with a radio access network and at least one processor. The at least one processor is configured to control the RF circuitry to receive a demodulation reference signal used to demodulate a broadcast channel, where the demodulation reference signal is transmitted on a first set of time and frequency resources individually assigned to each transmission point, and the broadcast channel is transmitted on the same second set of time and frequency resources from multiple transmission points. The at least one processor is further configured to determine, in part, an identifier or index for distinguishing between multiple beams or multiple synchronization signals and physical broadcast channel blocks transmitted from the multiple transmission points based at least on a location within a resource grid of the time and frequency resources at which the demodulation reference signal is received.

[0020] In a sixth aspect, a method performed by a wireless terminal includes the following steps: (a) receiving a demodulation reference signal used to demodulate a broadcast channel, wherein the demodulation reference signal is transmitted on a first set of time and frequency resources individually assigned to each transmission point, and the broadcast channel is transmitted on the same second set of time and frequency resources from multiple transmission points; and (b) determining a portion of an identifier or index for distinguishing multiple beams or multiple synchronization signals and physical broadcast channel blocks transmitted from the multiple transmission points based at least on a position within a resource grid of the time and frequency resources at which the demodulation reference signal is received.

[0021] A seventh aspect is directed to a program, which includes a set of instructions (software code) that, when loaded into a computer, causes the computer to perform the method according to the second, fourth, or sixth aspect.

[0022] According to the above-described aspects, it is possible to provide an apparatus, a method, and a program that contribute to solving at least one of a plurality of problems related to transmission and reception of broadcast signals, including the above-described problem.

[0023] 1 is a diagram illustrating an example of the configuration of a wireless communication system according to an embodiment. FIG. 1 is a diagram illustrating an example of the configuration of a transmission system of a base station according to an embodiment. FIG. 2 is a diagram illustrating an example of the configuration of a transmission system of a base station according to an embodiment. FIG. 3 is a flowchart illustrating an example of the operation of a base station according to an embodiment. FIG. 4 is a diagram for explaining an example of transmission of a plurality of SSBs according to an embodiment. FIG. 5 is a diagram illustrating an example of mapping of TRP-specific PBCH DMRS in an SSB according to an embodiment. FIG. 6 is a flowchart illustrating an example of the operation of a base station according to an embodiment. FIG. 7 is a diagram illustrating an example of the configuration of a UE according to an embodiment. FIG. 8 is a flowchart illustrating an example of the operation of a UE according to an embodiment. FIG. 9 is a diagram illustrating an example of mapping of TRP-specific PBCH DMRS and common PBCH DMRS in an SSB according to an embodiment. FIG. 10 is a sequence diagram illustrating an example of signaling between a base station and a UE according to an embodiment. FIG. 11 is a flowchart illustrating an example of the operation of a UE according to an embodiment. FIG. 12 is a diagram illustrating an example of the configuration of a TRP according to an embodiment. FIG. 13 is a diagram for explaining an example of transmission of a plurality of SSBs according to an embodiment. FIG. 14 is a block diagram illustrating an example of the configuration of a CU and a DU according to an embodiment. FIG. 15 is a block diagram illustrating an example of the configuration of a TRP according to an embodiment. FIG. 16 is a block diagram illustrating an example of the configuration of a UE according to an embodiment.

[0024] Hereinafter, specific embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are designated by the same reference numerals, and for clarity of explanation, duplicate explanations will be omitted as necessary.

[0025] The multiple embodiments described below can be implemented independently or in appropriate combination. These multiple embodiments have different novel features. Therefore, these multiple embodiments contribute to solving different purposes or problems and to achieving different effects.

[0026] The following embodiments are described primarily for the 3GPP 5G system, but may also be applied to other wireless communication systems that support beam sweeping techniques similar to the SSB beam sweeping in the 3GPP 5G system.

[0027] As used herein, depending on the context, "if" may be interpreted to mean "when," "at or around the time," "after," "upon," "in response to determining," "in accordance with a determination," or "in response to detecting." These expressions may be interpreted to have the same meaning, depending on the context.

[0028] First, the configurations and operations of several network elements common to several embodiments will be described. Figure 1 illustrates an example configuration of a wireless communication system according to several embodiments. In the example of Figure 1, the wireless communication system includes a Central Unit (CU) 10, Distributed Units (DUs) 21 and 22, TRPs 31 to 35, and UEs 40. The UEs 40 may be referred to by other terms, such as wireless terminals, mobile terminals, mobile stations, or wireless transmit receive units (WTRUs). Each element (network function) illustrated in Figure 1 can be implemented, for example, as a network element on dedicated hardware, as a software instance running on dedicated hardware, or as a virtualized function instantiated on an application platform.

[0029] The CU 10, the DUs 21 and 22, and the TRPs 31 to 35 correspond to one base station. In other words, one base station includes the CU 10, the DUs 21 and 22, and the TRPs 31 to 35. The base station may also be called a radio access network node, a radio station, or an access point. In a 5G system, the base station may be a gNB.

[0030] The CU 10 may host the RRC, Service Data Adaptation Protocol (SDAP), and Packet Data Convergence Protocol (PDCP) protocols of the gNB (or the RRC and PDCP protocols of the gNB). The CU 10 may include a Control Plane (CP) Unit (e.g., gNB-CU-CP) and one or more User Plane (UP) Units (e.g., gNB-CU-UPs).

[0031] Each of the DUs 21 and 22 hosts the Radio Link Control (RLC) layer and Medium Access Control (MAC) layer of the gNB, and may host part or all of the physical (PHY) layer of the gNB. If each of the DUs 21 and 22 hosts part of the PHY layer, i.e., the high PHY layer, the remaining PHY layer signal processing, i.e., the low PHY layer, is located in the TRPs 31 to 35. In the example of FIG. 1 , the DU 21 is connected to the TRPs 31 to 33, while the DU 22 is connected to the TRPs 34 and 35. The TRPs 31 to 33 provide one cell 51, and the TRPs 34 and 35 provide separate cells 52 and 53, respectively. In other words, the DU 21 provides one cell 51, and the TRPs 31 to 33 correspond to the cell 51. The DU 22 provides a plurality of cells 52 and 53, and the TRPs 34 and 35 correspond to the cells 52 and 53, respectively.

[0032] Each of the TRPs 31 to 35 can communicate with the UEs 40 using a beam. The TRPs 31 to 35 may also be called Radio Units (RUs), Remote Radio Heads (RRHs), access points (APs), or distributed antennas. When focusing only on downlink transmissions (e.g., SSB transmissions) by the base station, the TRPs may also be called transmission points.

[0033] Each of the TRPs 31-35 provides analog RF signal processing. Each TRP may also provide lower PHY layer signal processing. Each TRP includes or is connected to one or more antenna elements (typically array antennas). Each TRP includes RF components coupled to one or more antenna elements. For analog or hybrid beamforming, analog beamforming circuitry may be located between one or more antenna elements or one or more array antennas and the multiple RF chains of each TRP.

[0034] Each TRP may further include a digital front end (DFE). The DFE provides lower PHY layer signal processing and digital radio signal processing. The lower PHY layer signal processing may include, for example, an inverse fast Fourier transform (IFFT) for generating an OFDM signal and an FFT for obtaining subcarrier signal components from a received OFDM signal. The lower PHY layer signal processing may further include cyclic prefix (CP) addition and removal, and physical RACH (PRACH) extraction or filtering. The digital radio signal processing may include, for example, digital pre-distortion (DPD), crest factor reduction (CFR), digital up-conversion (DUC), digital down-conversion (DDC), and transmit and receive baseband channel filters. The DFE may perform digital baseband precoding for beamforming. For analog or hybrid beamforming, analog beamforming circuitry may be disposed between one or more antenna elements or one or more array antennas and the multiple RF chains of each TRP.

[0035] The DU 21 may be connected to each of the TRPs 31 to 33 via an interface conforming to a standard specification such as Common Public Radio Interface (CPRI), enhanced CPRI (eCPRI), or Open Radio Access Network (O-RAN) Fronthaul. Alternatively, the DU 21 may be connected to each of the TRPs 31 to 33 via an interface employing Radio over Fiber (RoF) technology. In this case, the DU 21 may perform all digital signal processing including upper and lower PHY layer signal processing, as well as Digital to Analog (DA) and Analog to Digital (AD) conversion.

[0036] A direct interface, connection, or backhaul may be provided to communicatively connect DU 21 and DU 22. Similarly, a direct interface, connection, or backhaul may be provided to communicatively connect TRPs within a cell or between cells, for example, between TRPs 31 to 33, between TRPs 33 and 34, and between TRPs 34 and 35.

[0037] FIG. 2 conceptually illustrates SSB beam sweeping performed by TRPs 31 to 33 within one cell (cell 51). Each of the TRPs 31 to 33 uses beam sweeping 300 to enable UEs 40 to select the best beam during initial access. Specifically, each TRP transmits multiple SSBs, changing the beam direction for each SSB transmission. One SSB includes PSS, SSS, PBCH, and PBCH DMRS. Note that when multiple TRPs are deployed within one cell, at least one of these TRPs may transmit only one SSB beam. In other words, at least one of the multiple TRPs within a cell may transmit a single SSB beam intermittently in a predetermined direction at a predetermined period without performing beam sweeping.

[0038] FIG. 3 shows an example configuration of a DU 21 and TRPs 31 to 33 that provide one cell (cell 51). In the example of FIG. 3, the DU 21 includes a digital baseband unit 210. The digital baseband unit 210 provides signal processing for the RLC layer, MAC layer, and upper PHY layer. For SSB transmission, the digital baseband unit 210 generates a Broadcast Channel (BCH) transport block containing a Master Information Block (MIB) message and generates a PBCH payload that includes the BCH transport block and additional timing-related PBCH payload bits. In addition, the digital baseband unit 210 performs scrambling, attachment of cyclic redundancy check (CRC) bits, channel coding, and rate matching on the generated PBCH payload. Furthermore, the digital baseband unit 210 performs scrambling on the rate-matched block of bits and maps the scrambled block of bits to multiple modulation symbols (e.g., complex-valued Quadrature Phase Shift Keying (QPSK) symbols).

[0039] Depending on the division of functions between the DU 21 and the TRPs 31 to 33, the digital baseband unit 210 may perform all digital signal processing, including lower PHY layer signal processing, as well as Digital to Analog (DA) and Analog to Digital (AD) conversion.

[0040] In the example of FIG. 3 , each of the TRPs 31 to 33 includes an RF component 310. The RF component 310 is coupled to an antenna 340. In the example of FIG. 3 , the antenna 340 includes multiple antenna elements and is typically an array antenna. The RF component 310 includes an RF transceiver 320 and a beamforming circuit 330. The RF transceiver 320 includes an amplifier and a frequency converter. The beamforming circuit 330 determines a beam direction by adjusting one or both of the phase and amplitude of radio signals supplied to the multiple antenna elements of the antenna 340. The specific beam direction or beam number is specified by the DU 21 or the CU 10. Other beamforming techniques may also be used, and the antenna 340 may be a directional antenna such as a lens antenna or a metamaterial antenna.

[0041] <First Embodiment> A configuration example of a wireless communication system according to this embodiment may be the same as the example described with reference to Figures 1 to 3. This embodiment provides operations of a base station and a UE regarding beam sweep transmission and reception of SSBs.

[0042] 4 shows an example of the operation of a base station transmission system for SSB transmission. The operations shown in FIG. 4 may be performed, for example, by a DU 21 connected to TRPs 31 to 33 in one cell (cell 51). The operations shown in FIG. 4 may be performed by a digital baseband unit 210 in the DU 21.

[0043] In step 401, the DU 21 controls each of the multiple TRPs 31 to 33 in the cell 51 to transmit a TRP-specific or individual PBCH DMRS in a first set of time and frequency resources that is individual for each TRP. The TRP-specific PBCH DMRS is used by the UEs 40 to demodulate one of the same set or different sets of modulation symbols generated from the same PBCH payload or different PBCH payloads. In other words, the base station transmission system transmits the DMRS used to demodulate the same set or different sets of modulation symbols generated from the same PBCH payload or different PBCH payloads from each of the multiple transmission points in a first set of time and frequency resources that is individual for each transmission point. The first set of time and frequency resources may be a set of resource elements.

[0044] In step 402, the DU 21 controls the TRPs 31 to 33 to transmit the same or different sets of PBCH modulation symbols in the same second set of time and frequency resources. In other words, the base station transmission system transmits the same or different sets of PBCH modulation symbols from multiple transmission points in the same second set of time and frequency resources. The second set of time and frequency resources may be a set of resource elements.

[0045] UE 40 receives TRP-specific PBCH DMRS on a first set of time and frequency resources that is separate for each TRP, and further receives one of the same or different sets of PBCH modulation symbols on a second set of time and frequency resources that is common to multiple TRPs.

[0046] In some implementations, UE 40 may estimate an individual channel response between each TRP and UE 40 based on reception of the TRP-specific PBCH DMRS and use the individual channel response to demodulate and decode the PBCH payload from one of the different sets of PBCH modulation symbols. Depending on the location of UE 40, UE 40 may receive SSB transmissions from multiple TRPs simultaneously, but UE 40 may be able to demodulate the PBCH payload of one SSB received with greater power.

[0047] In another implementation, UE 40 may estimate an individual channel response between each TRP and UE 40 based on reception of a TRP-specific PBCH DMRS, and calculate a composite channel response using multiple individual channel responses between multiple TRPs and UE 40. UE 40 may then demodulate and decode the same PBCH payload from the same set of PBCH modulation symbols using the composite channel response.

[0048] According to the operation described with reference to FIG. 4 , multiple TRPs simultaneously transmit multiple SSBs in the same set of second time and frequency resources. This can help reduce the overhead of SSB transmission (i.e., beam sweep transmission). In addition, according to the operation described with reference to FIG. 4 , UE 40 can receive a TRP-specific PBCH DMRS in a set of first time and frequency resources, each separate for each TRP. This allows UE 40 to measure the received power or reception quality of the TRP-specific PBCH DMRS in a set of first time and frequency resources, each separate for each TRP, and obtain measurements for each SSB beam. Therefore, the base station transmission system and the operation of UE 40 described with reference to FIG. 4 can help reduce the difficulty of UEs measuring the received power or reception quality for each SSB beam while reducing the overhead of SSB transmission. The received power may be Reference Signal Received Power (RSRP). The reception quality may be Reference Signal Received Quality (RSRQ) or Signal-to-Interference and Noise Ratio or Signal-to-Noise and Interference Ratio (SINR).

[0049] Figure 5 shows an example of SSB transmission by two TRPs within one SSB burst set. In the example of Figure 5, the maximum number of candidate time-domain positions where each TRP can transmit SSBs within one SSB burst set is L maxThe number of SSBs each TRP actually transmits is configurable and may be less than the maximum number. Two TRPs #0 and #1 share the same candidate time-domain location within the SSB burst set and transmit the PBCH 530 and PBCH 540 in the same time and frequency resources (resource elements). However, the two TRPs #0 and #1 transmit their respective TRP-specific PBCH DMRSs 510 and 520 in different time and frequency resources (resource elements) within each candidate time-domain location. Each time-domain location is a time-domain location in the mapping of time and frequency resources (resource elements). The candidate time-domain locations within the SSB burst set can also be referred to as transmission opportunities for SSBs within the SSB burst set.

[0050] By way of example and not limitation, L max The number of SSB bursts per SSB burst set may be 64, the same as in the current NR specification. The duration of an SSB burst set may also be a half radio frame, i.e., 5 ms, the same as in the current NR specification. Even in this case, in the example of FIG. 5, two TRPs #0 and #1 can transmit a total of up to 128 SSB beams in one SSB burst set. Additionally, UE 40 can obtain received power or quality measurements for each of TRP-specific PBCH DMRSs 510 and 520 by measuring different time and frequency resources (resource elements).

[0051] Figure 6 shows an example of mapping of TRP-specific PBCH DMRS within an SSB. In the example of Figure 6, one SSB is extended to span five consecutive OFDM symbols in the time domain. The frequency-domain resources occupied by the SSB in Figure 6 are 240 subcarriers or 20 resource blocks, the same as those of SSBs in the existing NR specifications. In the example of Figure 6, the TRP-specific PBCH DMRS for one TRP is mapped to a set of resource elements 600. Multiple resource elements 600 are located in the same OFDM symbol #1 in the time domain and are spaced 10 subcarriers apart from each other in the frequency domain. That is, in the example of Figure 6, the 240 resource elements in OFDM symbol #1 can transmit TRP-specific PBCH DMRSs for up to 10 TRPs. The resource element numbers to which the TRP-specific PBCH DMRS for each TRP is mapped can be expressed as follows: Here, TRP ID is 0 or more and N TRP is an integer smaller than N TRP is the maximum number of TRPs in a cell. In the example of Figure 6, N TRP is 10.

[0052] Figure 7 shows another example of mapping of TRP-specific PBCH DMRSs within an SSB. In the example of Figure 7, one SSB is extended to span six consecutive OFDM symbols in the time domain. The frequency-domain resources occupied by the SSB in Figure 7 are 2,240 subcarriers or 20 resource blocks, the same as SSBs in existing NR specifications. In the example of Figure 7, the TRP-specific PBCH DMRSs of one TRP are mapped to a set of resource elements 700. The multiple resource elements 700 are located in OFDM symbols #1, #3, and #5 in the time domain.

[0053] By arranging the TRP-specific PBCH DMRS in the time direction, the frequency offset and phase noise for each TRP can be estimated from the phase rotation of the TRP-specific channel estimate in the time direction. The UE 40 may perform one or both of frequency offset compensation and phase noise compensation in advance, and then estimate the composite channel using the compensated dedicated channel estimate. In addition, by arranging the TRP-specific PBCH DMRS in the time direction, the UE 40 can receive the TRP-specific PBCH DMRS with multiple receive beams within one SSB transmission. In other words, the UE 40 can try multiple receive beams for the UE 40 in each SSB when searching for the best receive beam.

[0054] Second Embodiment A configuration example of a wireless communication system according to this embodiment may be similar to the example described with reference to Figures 1 to 3. This embodiment provides details of the operation of the base station and UE regarding SSB transmission and reception described in the first embodiment.

[0055] Fig. 8 shows an example of the operation of a base station transmission system for SSB transmission. The operation shown in Fig. 8 may be performed, for example, by a DU 21 connected to TRPs 31 to 33 in one cell (cell 51). The operation shown in Fig. 4 may be performed by a baseband unit 210 in the DU 21.

[0056] Steps 801 and 802 are similar to steps 401 and 402 of Figure 4. However, in step 802, the DU 21 controls the TRPs 31 to 33 to transmit the same set of PBCH modulation symbols generated from the same PBCH payload in the same second set of time and frequency resources. In other words, the base station transmission system transmits the same set of PBCH modulation symbols from multiple transmission points in the same second set of time and frequency resources. The second set of time and frequency resources may be a set of resource elements.

[0057] UE 40 receives TRP-specific PBCH DMRSs on a first set of time and frequency resources that are individual for each TRP. Furthermore, UE 40 receives the same set of PBCH modulation symbols on a second set of time and frequency resources that are common to multiple TRPs. UE 40 may estimate individual channel responses between each TRP and UE 40 based on the reception of the TRP-specific PBCH DMRSs, and may calculate a composite channel response using the multiple individual channel responses between the multiple TRPs and UE 40. Then, UE 40 may demodulate and decode the same PBCH payload from the same set of PBCH modulation symbols using the composite channel response.

[0058] FIG. 9 shows an example configuration of a UE 40. In the example of FIG. 9, the UE 40 includes an antenna 910, an RF transceiver 920, and a digital baseband processor 930. The RF transceiver 920 performs analog RF signal processing for communication with TRPs. The RF transceiver 920 may include multiple transceivers. The analog RF signal processing performed by the RF transceiver 920 includes frequency upconversion, frequency downconversion, and amplification. The RF transceiver 920 is coupled to the antenna 910 and the digital baseband processor 930. The RF transceiver 920 receives modulation symbol data (or OFDM symbol data) from the digital baseband processor 930, generates a transmit RF signal, and provides the transmit RF signal to the antenna 910. The RF transceiver 920 also generates a baseband receive signal based on the receive RF signal received by the antenna 910 and provides the baseband receive signal to the digital baseband processor 930. The RF transceiver 920 may include analog beamformer circuitry for beamforming, which may include, for example, multiple phase shifters and multiple power amplifiers.

[0059] The digital baseband processor 930 performs digital baseband signal processing (data plane processing) for wireless communication, including (a) data compression / decompression, (b) data segmentation / concatenation, (c) generation / decomposition of transmission formats (transmission frames), (d) transmission path coding / decoding, (e) modulation (symbol mapping) / demodulation, and (f) generation of OFDM symbol data (baseband OFDM signal) by IFFT.

[0060] 9 shows the processing performed by the digital baseband processor 930 for PBCH decoding. These include individual channel estimation 950, individual channel interpolation 960, combined channel estimation 970, and demodulation 980. The PBCH decoding process is described below. The following symbols are used in this description:

[0061] The UE 40 searches for the frequency on which the SSBs or SSB beams are transmitted. To search for the PSS, the UE 40 correlates the frequency-shifted received waveform with each possible PSS sequence and finds the strongest correlation peak. The UE 40 demodulates the synchronized waveform based on the timing and frequency offset at which the strongest correlation peak is located and extracts the SSB. The UE 40 extracts resource elements associated with the SSS from the received resource grid and correlates them with each possible locally generated SSS sequence. A resource grid is a time-frequency representation of the radio resources available for transmission. A resource grid is a collection of multiple resource elements or resource blocks available for transmission, i.e., consisting of multiple subcarriers in the frequency domain and multiple OFDM symbols in the time domain. A resource grid may be characterized or defined by the full or whole carrier bandwidth in the frequency domain and one subframe in the time domain. Based on the detected PSS and SSS sequences, the UE 40 identifies or calculates a physical layer cell identity (PCI). If the initial access has already been completed and the UE 40 has identified the physical layer cell ID or PCI, the UE 40 may use the synchronization signal sequence corresponding to the identified PCI for synchronization processing, i.e., PSS and SSS search.

[0062] After completing the SSS search, UE 40 searches for TRP-specific PBCH DMRS. UE 40 constructs each possible TRP-specific PBCH DMRS sequence and performs dedicated channel estimation 950. Since only DMRS from one TRP is received at a resource location for a TRP-specific PBCH DMRS, the channel response can be estimated as follows:

[0063] Next, the UE 40 performs dedicated channel interpolation 960. The UE 40 can use any interpolation method, such as linear interpolation. Specifically, the UE 40 interpolates (interpolates or extrapolates) the channel estimates for each TRP in the frequency direction (or time direction). As a result, the UE 40 obtains channel estimates for resource positions where the TRP-specific PBCH DMRS for that TRP is not transmitted, as follows: Here, K is the number of SSB subcarriers (e.g., 240).

[0064] The UE 40 then performs composite channel estimation 970. Using the interpolated individual channel estimates for each TRP, the UE 40 estimates the composite channel of multiple TRPs as follows:

[0065] Finally, the UE 40 performs demodulation 980. The same PBCH modulation symbols transmitted on the same time and frequency resource from multiple TRPs are spatially combined and received at the UE 40 as follows:

[0066] The UE 40 performs a demodulation process on the detected PBCH symbols using the derived composite channel response estimate. The UE 40 demodulates the common PBCH payload as follows:

[0067] 10 shows an example of a PBCH decoding process by UE 40. In step 1001, UE 40 estimates an individual channel response between each TRP and UE 40 based on reception of the TRP-specific PBCH DMRS. This corresponds to individual channel estimation 950. In step 1002, UE 40 calculates a composite channel response using multiple individual channel responses between multiple TRPs and the UE. This corresponds to individual channel interpolation 960 and composite channel estimation 970 described above. In step 1003, UE 40 demodulates the same PBCH payload from the same set of PBCH modulation symbols using the composite channel response. This corresponds to demodulation 980 described above.

[0068] According to the operations described with reference to Figures 8 to 10, the base station transmission system transmits the same set of PBCH modulation symbols generated from the same PBCH payload from multiple TRPs on the same set of second time and frequency resources. In addition, the base station transmission system transmits TRP-specific PBCH DMRS on a separate set of first time and frequency resources for each TRP. As described in the first embodiment, the UE 40 can receive the TRP-specific PBCH DMRS on a separate set of first time and frequency resources for each TRP. This allows the UE 40 to measure the received power or reception quality of the TRP-specific PBCH DMRS on a separate set of first time and frequency resources for each TRP and obtain measurements for each SSB beam. In addition, the UE 40 can estimate individual channel responses between the UE 40 and each of the multiple TRPs based on the reception of the TRP-specific PBCH DMRS from the multiple TRPs, and can further determine a composite channel response required for demodulating the PBCH symbol common to the multiple TRPs. This allows UE 40 to perform spatial multipath combining of common PBCH symbols transmitted from multiple TRPs. By allowing multiple TRPs to transmit PBCH symbols on the same radio resource, the overhead required for SSB beam sweeping is reduced.

[0069] In addition to TRP-specific PBCH DMRS, the base station may transmit common PBCH DMRS, i.e., PBCH DMRS with the same sequence, from multiple TRPs in the same time and frequency resources. The sequence of the common PBCH DMRS may be generated based on the number or index of the time-domain position where the common PBCH DMRS is transmitted within the SSB burst set. For example, the common PBCH DMRS sequence may be a pseudo-random sequence, and the initial value for generating the pseudo-random sequence may be generated based on the time-domain position number or index. UE 40 may then correlate the received waveform of the common PBCH DMRS with each of the possible candidate sequences based on the time-domain position number or index. This allows UE 40 to identify the number or index of the time-domain position within the SSB burst set where the common PBCH DMRS is transmitted based on the strongest correlation peak.

[0070] In addition, common PBCH DMRSs transmitted from multiple TRPs on the same time and frequency resources can be used by UE 40 to estimate a composite channel required to demodulate the same PBCH symbol and obtain the same PBCH payload. UE 40 may use a composite channel estimate calculated based on the TRP-specific PBCH DMRSs together with a composite channel estimate calculated based on the common PBCH DMRSs. This can improve the accuracy of the composite channel estimate.

[0071] Figure 11 shows an example of mapping of TRP-specific PBCH DMRS and common PBCH DMRS within an SSB. In the example of Figure 11, the TRP-specific PBCH DMRS of one TRP is mapped to a set of resource elements 1100. This is the same as the mapping of the TRP-specific PBCH DMRS shown in Figure 6. In addition, in the example of Figure 11, the common PBCH DMRS is mapped to a set of resource elements 1120. The resource elements 1120 are located in OFDM symbols #2, #3, and #4 in the time domain.

[0072] <Third Embodiment> A configuration example of a wireless communication system according to this embodiment may be similar to the example described with reference to Figures 1 to 3. This embodiment provides details of beam or SSB identification by the UE 40 with respect to SSB transmission and reception described in the first and second embodiments.

[0073] In a first implementation, the location of the first time and frequency resource set, which is individual for each TRP on which a TRP-specific PBCH DMRS is transmitted, is associated with the identity of the TRP (or transmission point). In a second implementation, the location of the first time and frequency resource set, which is individual for each TRP on which a TRP-specific PBCH DMRS is transmitted, is associated with at least a portion of an identifier or index for distinguishing between multiple beams or multiple SSBs transmitted from multiple TRPs. In these implementations, the UE 40 identifies or determines the identifier or index for distinguishing between multiple beams or multiple SSBs transmitted from multiple TRPs based at least on the locations of the individual first time and frequency resource sets. Note that the location of the first time and frequency resource set, which is individual for each TRP on which a TRP-specific PBCH DMRS is transmitted, refers to the location of these time and frequency resource sets within a resource grid. The location of the first time and frequency resource set may also be referred to as the arrangement, mapping pattern, transmission pattern, or allocation pattern of the first time and frequency resource set within a resource grid. A resource grid is a time-frequency representation of radio resources available for transmission. A resource grid is a collection of resource elements or resource blocks available for transmission, i.e., consisting of subcarriers in the frequency domain and OFDM symbols in the time domain. A resource grid may be characterized or defined by the full or whole carrier bandwidth in the frequency domain and a subframe in the time domain.

[0074] For the first and second implementations, the identifier or index for distinguishing between multiple beams or multiple SSBs may be divided into multiple fields, including at least a first field associated with a location within the resource grid of the respective first set of time and frequency resources. The multiple fields may further include at least one of the following: a second field carried in the PBCH payload, a third field carried with a sequence of TRP-specific PBCH DMRS, a fourth field carried with a sequence of PBCH DMRS common to multiple TRPs, and a fifth field carried with a sequence of PSS or SSS.

[0075] In a third implementation, the TRP-specific PBCH DMRS has a different sequence for each TRP by being generated based on the identification information of each TRP. In a fourth implementation, the TRP-specific PBCH DMRS has a different sequence for each TRP by being generated based on an identifier or index for distinguishing between multiple beams or multiple SSBs transmitted from multiple previous TRPs. In these implementations, UE 40 identifies or determines the identifier or index for distinguishing between multiple beams or multiple SSBs based at least on the sequence of the TRP-specific PBCH DMRS received on the respective first set of time and frequency resources.

[0076] For the third and fourth implementations, the identifier or index for distinguishing between multiple beams or multiple SSBs may be divided into multiple fields, including at least a first field transmitted in a TRP-specific PBCH DMRS sequence. The multiple fields may further include at least one of the following: a second field carried in the PBCH payload, a third field carried in a PBCH DMRS sequence common to multiple TRPs, and a fourth field carried in a PSS or SSS sequence.

[0077] In the first through fourth implementations, UE 40 may measure received power or received quality on a first set of individual time and frequency resources carrying a TRP-specific PBCH DMRS. UE 40 may then determine the best beam or best SSB based on the received power or received quality measurements and the identified beam or SSB identifier (or index). Additionally or alternatively, UE 40 may report the measured received power or received quality to a radio access network (e.g., a base station) in association with the identified beam or SSB identifier (or index).

[0078] <Fourth Embodiment> A configuration example of a wireless communication system according to this embodiment may be similar to the example described with reference to Figures 1 to 3. This embodiment provides details of the placement of TRP-specific PBCH DMRS within an SSB with respect to the SSB transmission and reception described in the first and second embodiments.

[0079] The base station transmission system may shift the time and frequency resources (e.g., resource elements) to which the TRP-specific PBCH DMRS is mapped within an SSB according to or depending on the physical layer cell identifier (PCI). In other words, the base station transmission system may change the placement or mapping of the TRP-specific PBCH DMRS within an SSB based on the physical layer cell identifier. UE 40 may assume that the placement or mapping of the TRP-specific PBCH DMRS within an SSB is changed in this manner. This contributes to reducing inter-cell interference of the TRP-specific PBCH DMRS. For example, the resource element number to which the TRP-specific PBCH DMRS for each TRP is mapped can be expressed by the following formula: Here, c is expressed by the following formula: Here, TRP ID is 0 or more and N TRP is an integer smaller than N TRP is the maximum number of TRPs in a cell, and N ID cell is a physical layer cell identifier, and k is an integer greater than or equal to zero. ID cell is indicated by the sequences PSS and SSS.

[0080] Additionally or alternatively, the base station transmission system may vary the time and frequency resources (e.g., resource elements) to which the TRP-specific PBCH DMRS is mapped within an SSB depending on or in response to the number of TRPs (or transmission points) that may be used or are being used within a cell. In other words, the base station transmission system may vary the placement or mapping of the TRP-specific PBCH DMRS within an SSB based on the number of TRPs that may be used or are being used within a cell. In yet another way, the base station transmission system may vary the placement or mapping of the TRP-specific PBCH DMRS within an SSB depending on or in response to the number of TRPs that may be or are being simultaneously transmitted in one candidate time-domain position within an SSB burst set. Alternatively, the base station transmission system may vary the placement or mapping of the TRP-specific PBCH DMRS within an SSB depending on or in response to the number of SSBs or beams that may be or are being simultaneously transmitted in one candidate time-domain position within an SSB burst set. UE 40 may thus assume that the placement or mapping of TRP-specific PBCH DMRS within an SSB is changed.

[0081] In this case, as shown in Figure 12, base station (BS) 1201 notifies UE 40 of the number of TRPs that can be or are being used in a cell (step 1221). Alternatively, base station 1201 notifies UE 40 of the number of TRPs that can or are being simultaneously transmitted at one candidate time domain location within an SSB burst set. Alternatively, base station 1201 notifies UE 40 of the number of SSBs or beams that can or are being simultaneously transmitted at one candidate time domain location within an SSB burst set. Base station 1201 is, for example, CU 10 or DU 21. This enables UE 40 to determine the placement or mapping of TRP-specific PBCH DMRS.

[0082] More specifically, the base station 1201 transmits an indication of the number of TRPs that can be used or are being used in a cell (e.g., cell 51) using a signal, physical channel, or message received by at least a plurality of idle wireless terminals. In other words, the base station 1201 broadcasts an indication of the number of TRPs that can be used or are being used in a cell (e.g., cell 51). The indication may indicate the number of TRPs that can be or are transmitting SSBs simultaneously in a candidate time-domain location within an SSB burst set in the cell. In other words, the indication may indicate the number of TRPs that can be or are transmitting the same set of PBCH symbols or different sets of PBCH symbols in the same second set of time and frequency resources. In yet another way, the indication may indicate the number of SSBs or SSB beams that can be or are being transmitted simultaneously in a candidate time-domain location within an SSB burst set in the cell. The indication of the number of TRPs may be referred to as information, data, configuration, or configuration information indicating the number of TRPs.

[0083] The base station may transmit the indication using a signal or physical channel included in an SSB. Alternatively, the base station may transmit the indication using System Information Block Type 1 (SIB1). The base station may transmit the indication using another SIB. The indication may be divided into multiple fields and transmitted over multiple signal or physical channels.

[0084] In one implementation, the base station may provide this indication to the UEs 40 using at least a sequence of synchronization signals, i.e., PSS or SSS, transmitted within the SSB. Additionally or alternatively, the base station may provide this indication to the UEs 40 using at least a sequence of common PBCH DMRS transmitted from multiple TRPs on the same time and frequency resources within the SSB.

[0085] In other implementations, the base station may provide the indication to the UE 40 using at least the PBCH payload (e.g., MIB) transmitted from multiple TRPs on the same time and frequency resources within an SSB. Additionally or alternatively, the base station may provide the indication to the UE 40 using at least the configuration information within SIB1. In these cases, the UE 40 cannot determine the number of simultaneously transmitting TRPs or simultaneously transmitting SSB beams until it decodes one or both of the PBCH payload (e.g., MIB) and SIB1. Therefore, the UE 40 cannot determine the location of the TRP-specific PBCH DMRS within the SSB until it decodes one or both of the PBCH payload (e.g., MIB) and SIB1. For this reason, the base station must transmit a PBCH DMRS common to multiple TRPs within the SSB to enable the UE 40 to estimate the composite channel and decode the PBCH payload.

[0086] UE 40 may determine, based on the indication, the number of TRPs that can or are transmitting SSBs simultaneously at a candidate time-domain location within an SSB burst set in the cell. In other words, UE 40 may determine, based on the indication, the number of SSBs or SSB beams that can or are transmitting simultaneously at a candidate time-domain location within an SSB burst set in the cell. In yet another way, UE 40 may determine the placement or mapping of TRP-specific PBCH DMRSs within an SSB based on the indication.

[0087] 13 illustrates an example of the operation of UE 40. In step 1301, UE 40 receives a first indication, via a signal or physical channel in an SSB or SIB1, indicating the number of TRPs that may be used or are being used in a cell. In step 1302, UE 40 determines the location of time and frequency resources individually allocated for each TRP in which a TRP-specific PBCH DMRS is transmitted, based on the received first indication.

[0088] Fifth Embodiment A configuration example of a wireless communication system according to this embodiment may be the same as the example described with reference to Figures 1 to 3. This embodiment provides details of SSB transmission in a configuration in which each TRP has multiple subarrays.

[0089] FIG. 14 shows an example configuration of TRPs 31, 32, and 33. In the example of FIG. 14, each of TRPs 31 to 33 includes an RF component 1410. RF component 1410 is coupled to two antenna subarrays 1440A and 1440B. RF component 1410 includes an RF transceiver 1420 and beamforming circuits 1430A and 1430B. Beamforming circuit 1430A determines a beam direction by adjusting either or both of the phase and amplitude of radio signals provided to multiple antenna elements of antenna subarray 1440A. Similarly, beamforming circuit 1430B determines a beam direction by adjusting either or both of the phase and amplitude of radio signals provided to multiple antenna elements of antenna subarray 1440B.

[0090] Each TRP transmits multiple SSB beams from multiple antenna subarrays at the same candidate time-domain locations within the SSB burst set using different frequency resources (e.g., subcarriers). For example, each TRP transmits the same or a different set of PBCH modulation symbols from the first antenna subarray 1440A at a second set of time and frequency resources common to multiple TRPs, but not from the second antenna subarray 1440B at the second set of time and frequency resources. This reduces the time required to transmit all SSBs or SSB beams. In other words, this contributes to completing the transmission of all SSBs or SSB beams at fewer candidate time-domain locations.

[0091] Figure 15 shows an example of SSB transmissions within one SSB burst set from multiple antenna subarrays of one TRP. In the example of Figure 15, the maximum number of candidate time-domain positions at which SSBs can be transmitted within one SSB burst set is Lmax The number of SSBs each TRP actually transmits is configurable and may be less than the maximum number. TRP #0 comprises antenna subarrays A and B. Antenna subarrays A and B simultaneously transmit two SSBs on different frequency resources (or subcarriers) while sharing the same candidate time-domain location within the SSB burst set. For example, for candidate time-domain location #0, antenna subarrays A and B transmit SSB 1510 (SSB #0) and SSB 1520 (SSB #1) on different frequency resources.

[0092] As described in the fourth embodiment, the base station may vary the placement or mapping of TRP-specific PBCH DMRS within an SSB depending on or in response to the number of SSBs or beams that can be or are being simultaneously transmitted at one candidate time-domain location within the SSB burst set. In this case, the base station may inform UE 40 of the number of TRPs that can be or are being used in the cell, as well as the maximum number of subarrays for each TRP.

[0093] Next, exemplary configurations of the CU 10, DUs 21 and 22, TRPs 31 to 35, and UE 40 shown in FIG. 1 will be described. FIG. 16 is a block diagram showing an exemplary configuration of the CU 10. The configuration of the DUs 21 and 22 may also be similar to the configuration shown in FIG. 16. Referring to FIG. 16, the CU 10 includes a network interface 1601, a processor 1602, and a memory 1603. The network interface 1601 is used to communicate with network nodes (e.g., DUs, and control plane (CP) nodes and / or user plane (UP) nodes in the core network). The network interface 1601 may include multiple interfaces. The network interface 1601 may include, for example, an optical fiber interface for CU-DU communication and a network interface compliant with IEEE 802.3 series.

[0094] The processor 1602 may include multiple processors. If the CU 10 is a CU-CP, the processor 1602 performs, for example, control plane processing, such as processing related to NGAP, RRC, E1AP, and F1AP signaling. If the CU 10 includes a CU-UP, the processor 1602 performs, for example, termination of the NG-U interface, termination of the F1-U interface, and data processing for the SDAP and PDCP layers.

[0095] In the case of the DUs 21 and 22, the processor 1602 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. For example, the processor 1602 may include a modem processor (e.g., a Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (e.g., a Central Processing Unit (CPU) or a Micro Processing Unit (MPU)) that performs control plane processing. The digital baseband signal processing may include signal processing for the RLC, MAC, and PHY layers. The control plane processing may include processing of MAC CEs and DCIs. The processor 1602 may include a digital beamformer module for beamforming. The digital beamformer module may include a multi-input multi-output (MIMO) encoder and precoder.

[0096] The memory 1603 is configured by a combination of volatile memory and non-volatile memory. The volatile memory is, for example, Static Random Access Memory (SRAM), Dynamic RAM (DRAM), or a combination thereof. The non-volatile memory is, for example, Mask Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or a hard disk drive, or any combination thereof. The memory 1603 may include storage located remotely from the processor 1602. In this case, the processor 1602 may access the memory 1603 via the network interface 1601 or another I / O interface.

[0097] The memory 1603 may store one or more software modules (computer programs) 1604 including instructions and data for performing the processing by the CU 10 described in the above-described embodiments. In some implementations, the processor 1602 may be configured to read and execute the one or more software modules 1604 from the memory 1603 to perform the processing by the CU 10 described in the above-described embodiments.

[0098] FIG. 17 is a block diagram showing an example configuration of the TRPs 31 to 35. Referring to FIG. 17, each of the TRPs 31 to 35 includes an RF transceiver 1701, a network interface 1703, a processor 1704, and a memory 1705. The RF transceiver 1701 performs analog RF signal processing for communication with UEs. The RF transceiver 1701 may include multiple transceivers. The RF transceiver 1701 is coupled to an antenna array 1702 and a processor 1704. The RF transceiver 1701 receives modulation symbol data from the processor 1704, generates a transmit RF signal, and provides the transmit RF signal to the antenna array 1702. The RF transceiver 1701 also generates a baseband receive signal based on the receive RF signal received by the antenna array 1702 and provides the baseband receive signal to the processor 1704. The RF transceiver 1701 may include an analog beamformer circuit for beamforming. The analog beamformer circuitry includes, for example, multiple phase shifters and multiple power amplifiers.

[0099] The network interface 1703 is used to communicate with network nodes (e.g., DUs, other TRPs). The network interface 1703 may include multiple interfaces. For example, the network interface 1703 may include an optical fiber interface for DU-TRP communication (and inter-TRP communication) and a network interface compliant with the IEEE 802.3 series.

[0100] The processor 1704 may include one or more processors. The processor 1704 may include a DFE and a controller. The DFE provides lower PHY layer signal processing and digital radio signal processing.

[0101] The memory 1705 is configured by a combination of volatile memory and non-volatile memory. The volatile memory is, for example, SRAM or DRAM, or a combination thereof. The non-volatile memory is, for example, MROM, EEPROM, flash memory, or a hard disk drive, or any combination thereof. The memory 1705 may include storage located remotely from the processor 1704. In this case, the processor 1704 may access the memory 1705 via the network interface 1703 or an I / O interface (not shown).

[0102] The memory 1705 may store one or more software modules (computer programs) 1706 including instructions and data for performing at least a portion of the processing by the TRPs 31 to 35 described in the above embodiments. In some implementations, the processor 1704 may be configured to read and execute the software modules 1706 from the memory 1705 to perform at least a portion of the processing by the TRPs 31 to 35 described in the above embodiments.

[0103] FIG. 18 is a block diagram showing an example configuration of a UE 40. An RF transceiver 1801 performs analog RF signal processing for communication with TRPs. The RF transceiver 1801 may include multiple transceivers. The analog RF signal processing performed by the RF transceiver 1801 includes frequency up-conversion, frequency down-conversion, and amplification. The RF transceiver 1801 is coupled to an antenna array 1802 and a baseband processor 1803. The RF transceiver 1801 receives modulation symbol data (or OFDM symbol data) from the baseband processor 1803, generates a transmit RF signal, and provides the transmit RF signal to the antenna array 1802. The RF transceiver 1801 also generates a baseband receive signal based on the receive RF signal received by the antenna array 1802 and provides the baseband receive signal to the baseband processor 1803. The RF transceiver 1801 may include an analog beamformer circuit for beamforming. The analog beamformer circuitry includes, for example, multiple phase shifters and multiple power amplifiers.

[0104] The baseband processor 1803 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communications. Digital baseband signal processing includes (a) data compression / decompression, (b) data segmentation / concatenation, (c) transmission format (transmission frame) generation / decomposition, (d) transmission path coding / decoding, (e) modulation (symbol mapping) / demodulation, and (f) generation of OFDM symbol data (baseband OFDM signal) using Inverse Fast Fourier Transform (IFFT). Meanwhile, control plane processing includes communication management for Layer 1 (e.g., transmit power control), Layer 2 (e.g., radio resource management and hybrid automatic repeat request (HARQ) processing), and Layer 3 (e.g., signaling related to attachment, mobility, and call management).

[0105] For example, the digital baseband signal processing by the baseband processor 1803 may include signal processing of an SDAP layer, a PDCP layer, an RLC layer, a MAC layer, and a PHY layer. Also, the control plane processing by the baseband processor 1803 may include processing of a Non-Access Stratum (NAS) protocol, an RRC protocol, MAC CEs, and DCIs.

[0106] The baseband processor 1803 may perform MIMO encoding and precoding for beamforming.

[0107] The baseband processor 1803 may include a modem processor (e.g., DSP) that performs digital baseband signal processing and a protocol stack processor (e.g., CPU or MPU) that performs control plane processing. In this case, the protocol stack processor that performs control plane processing may be shared with the application processor 1804, which will be described later.

[0108] The application processor 1804 is also referred to as a CPU, MPU, microprocessor, or processor core. The application processor 1804 may include multiple processors (multiple processor cores). The application processor 1804 executes a system software program (operating system (OS)) and various application programs (e.g., a call application, a web browser, a mailer, a camera operation application, and a music playback application) read from the memory 1806 or a memory not shown, thereby realizing various functions of the UE 40.

[0109] In some implementations, the baseband processor 1803 and the application processor 1804 may be integrated on a single chip, as shown by the dashed line (1805) in Figure 18. In other words, the baseband processor 1803 and the application processor 1804 may be implemented as a single System on Chip (SoC) device 1805. An SoC device may also be called a system Large Scale Integration (LSI) or chipset.

[0110] The memory 1806 is volatile memory, nonvolatile memory, or a combination thereof. The memory 1806 may include multiple physically independent memory devices. The volatile memory is, for example, SRAM, DRAM, or a combination thereof. The nonvolatile memory is, for example, MROM, EEPROM, flash memory, or a hard disk drive, or any combination thereof. For example, the memory 1806 may include an external memory device accessible from the baseband processor 1803, the application processor 1804, and the SoC 1805. The memory 1806 may also include an internal memory device integrated within the baseband processor 1803, the application processor 1804, or the SoC 1805. Furthermore, the memory 1806 may include memory within a Universal Integrated Circuit Card (UICC).

[0111] The memory 1806 may store one or more software modules (computer programs) 1807 including instructions and data for performing the processing by the UE 40 described in the above-described embodiments. In some implementations, the baseband processor 1803 or the application processor 1804 may be configured to read and execute the software modules 1807 from the memory 1806, thereby performing the processing by the UE 40 described in the above-described embodiments using the drawings.

[0112] It should be noted that the control plane processing and operations performed by the UE 40 described in the above embodiment can be realized by elements other than the RF transceiver 1801 and the antenna array 1802, namely, at least one of the baseband processor 1803 and the application processor 1804, and the memory 1806 storing the software module 1807.

[0113] As described with reference to Figures 16, 17, and 18, each of the processors included in the CUs, DUs, TRPs, and UEs according to the above-described embodiments can execute one or more programs including instructions for causing a computer to perform the algorithms described with reference to the drawings. The programs include instructions (or software code) that, when loaded into a computer, cause the computer to perform one or more functions described in the embodiments. The programs may be stored on a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, computer-readable media or tangible storage media include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technology, CD-ROM, digital versatile disk (DVD), Blu-ray disc or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage, or other magnetic storage device. The programs may also be transmitted on a transitory computer-readable medium or communication medium. By way of example and not limitation, transitory computer-readable media or communication media include electrical, optical, acoustic, or other forms of propagated signals.

[0114] The above-described embodiments are merely examples of application of the technical ideas obtained by the inventors of the present invention. In other words, the technical ideas are not limited to the above-described embodiments, and various modifications are possible.

[0115] For example, some or all of the above embodiments can be described as, but are not limited to, the following supplementary notes.

[0116] (Supplementary Note 1) A transmission system of a base station, comprising: a plurality of transmission points; and a baseband unit configured to: control each of the plurality of transmission points to transmit, on a first set of time and frequency resources individual for each transmission point, a first demodulation reference signal used to demodulate one of the same set of modulation symbols or different sets of modulation symbols generated from the same broadcast channel payload or different broadcast channel payloads; and control the plurality of transmission points to transmit the same set of modulation symbols or the different sets of modulation symbols on a second set of time and frequency resources individual for each transmission point. (Supplementary Note 2) The transmission system according to Supplementary Note 1, wherein the baseband unit is configured to control the plurality of transmission points to transmit the same set of modulation symbols generated from the same broadcast channel payload on the second set of time and frequency resources. (Supplementary Note 3) The transmission system according to Supplementary Note 1 or 2, wherein a position within a resource grid of the individual first sets of time and frequency resources is associated with identification information of the transmission point. (Supplementary Note 4) The transmission system according to Supplementary Note 1 or 2, wherein the position of the respective first sets of time and frequency resources in a resource grid is associated with at least a part of an identifier or index for distinguishing between a plurality of beams or a plurality of synchronization signals and physical broadcast channel blocks transmitted from the plurality of transmission points. (Supplementary Note 5) The transmission system according to Supplementary Note 4, wherein the identifier or index is divided into a plurality of fields, and the plurality of fields include at least a first field associated with the position of the respective first sets of time and frequency resources in a resource grid.(Supplementary Note 6) The multiple fields further include at least one of the following: a second field carried in the broadcast channel payload, a third field carried in the sequence of the first demodulation reference signal, a fourth field carried in the sequence of second demodulation reference signals transmitted from the multiple transmission points in the same third set of time and frequency resources, and a fifth field carried in the sequence of synchronization signals transmitted from the multiple transmission points in the same fourth set of time and frequency resources. The transmission system according to Supplementary Note 5. (Supplementary Note 7) The transmission system according to any one of Supplements 1 to 4, wherein the first demodulation reference signal has a different sequence for each transmission point by being generated based on identification information of the transmission point. (Supplementary Note 8) The transmission system according to any one of Supplements 1 to 4, wherein the first demodulation reference signal has a different sequence for each transmission point by being generated based on an identifier or index for distinguishing between multiple beams or multiple synchronization signals and physical broadcast channel blocks transmitted from the multiple transmission points. (Supplementary Note 9) The transmission system according to Supplementary Note 8, wherein the identifier or index is divided into a plurality of fields, and the plurality of fields includes at least a first field transmitted in the sequence of the first demodulation reference signal. (Supplementary Note 10) The plurality of fields further includes at least one of the following: a second field carried in the broadcast channel payload, a third field carried in the sequence of second demodulation reference signals transmitted from the plurality of transmission points in the same third set of time and frequency resources, and a fourth field carried in the sequence of synchronization signals transmitted from the plurality of transmission points in the same fourth set of time and frequency resources. The transmission system according to Supplementary Note 9, wherein the identifier or index is divided into a plurality of fields, and the plurality of fields includes at least a first field transmitted in the sequence of the first demodulation reference signal. (Supplementary Note 10) The transmission system according to Supplementary Note 9, wherein the plurality of fields further includes at least one of the following: a second field carried in the broadcast channel payload, a third field carried in the sequence of second demodulation reference signals transmitted from the plurality of transmission points in the same third set of time and frequency resources.(Supplementary Note 11) The transmission system according to any one of Supplementary Notes 1 to 10, wherein the baseband unit is configured to indicate the total number of transmission points in a cell transmitting on the same second set of time and frequency resources or the total number of beams in a cell transmitted on the same second set of time and frequency resources by using at least a sequence of synchronization signals transmitted from the multiple transmission points on the same set of time and frequency resources. (Supplementary Note 12) The transmission system according to any one of Supplementary Notes 1 to 10, wherein the baseband unit is configured to indicate the total number of transmission points in a cell transmitting on the same second set of time and frequency resources or the total number of beams in a cell transmitted on the same second set of time and frequency resources by using at least a sequence of second demodulation reference signals transmitted from the multiple transmission points on the same set of time and frequency resources. (Supplementary Note 13) The transmission system according to any one of Supplements 1 to 10, wherein the baseband unit is configured to indicate, by at least using the Broadcast Channel Payload, the total number of transmission points in a cell transmitting on the same second set of time and frequency resources or the total number of beams in a cell transmitted on the same second set of time and frequency resources. (Supplementary Note 14) The transmission system according to any one of Supplements 1 to 10, wherein the baseband unit is configured to indicate, by at least using configuration information in System Information Block Type 1 (SIB1), the total number of transmission points in a cell transmitting on the same second set of time and frequency resources or the total number of beams in a cell transmitted on the same second set of time and frequency resources.(Supplementary Note 15) The transmission system of any one of Supplements 1 to 14, wherein each transmission point is coupled to a first and a second antenna subarray, and each transmission point is configured to: transmit one of the same set of modulation symbols or the different sets of modulation symbols from the first antenna subarray in the same second set of time and frequency resources, and not transmit from the second antenna subarray in the same second set of time and frequency resources. (Supplementary Note 16) The transmission system of any one of Supplements 1 to 15, wherein the individual sets of first time and frequency resources carrying the first demodulation reference signal of each transmission point and the same set of second time and frequency resources carrying the same set of modulation symbols or the different sets of modulation symbols are included in a synchronization signal and physical broadcast channel block, together with sets of time and frequency resources carrying one or more synchronization signals. (Supplementary Note 17) The transmission system of any one of Supplements 1 to 16, wherein the multiple transmission points are located in one cell and associated with the same cell identifier. (Supplementary Note 18) A method performed by a transmission system of a base station, comprising: transmitting, from each of a plurality of transmission points, a first demodulation reference signal used to demodulate one of the same set or different sets of modulation symbols generated from the same broadcast channel payload or different broadcast channel payloads, in a first set of time and frequency resources individual for each transmission point; and transmitting the same set of modulation symbols or the different sets of modulation symbols from the plurality of transmission points in the same second set of time and frequency resources.(Supplementary Note 19) A program comprising a plurality of instructions, when executed by at least one processor of a transmission system of a base station, causing the transmission system to perform a method, the method comprising: controlling a plurality of transmission points to transmit, on a first set of time and frequency resources distinct for each transmission point, a first demodulation reference signal used to demodulate one of the same set of modulation symbols or different sets of modulation symbols generated from the same broadcast channel payload or different broadcast channel payloads; and controlling the plurality of transmission points to transmit the same set of modulation symbols or the different sets of modulation symbols on a same second set of time and frequency resources. and at least one processor coupled to the RF circuit, wherein the at least one processor is configured to: control the RF circuit to receive, on a first set of time and frequency resources individual for each transmission point, a first demodulation reference signal used to demodulate one of the same or different sets of modulation symbols generated from the same broadcast channel payload or different broadcast channel payloads; and control the RF circuit to receive, on a second set of time and frequency resources common to a plurality of transmission points. (Supplementary Note 21) The wireless terminal of Supplementary Note 20, comprising: a Radio Frequency (RF) circuit configured to communicate with a radio access network; and at least one processor coupled to the RF circuit, wherein the at least one processor is configured to: control the RF circuit to receive, on a first set of time and frequency resources individual for each transmission point, a first demodulation reference signal used to demodulate one of the same or different sets of modulation symbols generated from the same broadcast channel payload or different broadcast channel payloads; and control the RF circuit to receive, on a second set of time and frequency resources common to a plurality of transmission points.(Supplementary Note 22) The wireless terminal of Supplementary Note 21, wherein the at least one processor is configured to: estimate an individual channel response between each transmission point and the wireless terminal based on reception of the first demodulation reference signal, calculate a composite channel response using multiple individual channel responses between the multiple transmission points and the wireless terminal, and demodulate the same broadcast channel payload from the same set of modulation symbols using the composite channel response. (Supplementary Note 23) The wireless terminal of any one of Supplementary Notes 20 to 22, wherein the at least one processor is configured to identify identifiers or indexes for distinguishing between multiple beams or multiple synchronization signals and physical broadcast channel blocks transmitted from the multiple transmission points based at least on positions of the individual first sets of time and frequency resources within a resource grid. (Supplementary Note 24) The wireless terminal of any one of Supplementary Notes 20 to 22, wherein the at least one processor is configured to identify identifiers or indexes for distinguishing between multiple beams or multiple synchronization signals and physical broadcast channel blocks transmitted from the multiple transmission points based at least on a sequence of the first demodulation reference signals received on the respective first sets of time and frequency resources. (Supplementary Note 25) The wireless terminal of Supplementary Note 23 or 24, wherein the at least one processor is configured to: measure a received power or a received quality on the respective sets of first time and frequency resources carrying the first demodulation reference signals, and determine a best beam or best synchronization signal and physical broadcast channel block based on the received power or received quality and the identifier or index. (Supplementary Note 26) The wireless terminal of Supplementary Note 23 or 24, wherein the at least one processor is configured to: measure a received power or a received quality in the individual first set of time and frequency resources carrying the first demodulation reference signal; and report the received power or the received quality to the radio access network in association with the identifier or index.(Supplementary Note 27) The wireless terminal of any one of Supplementary Notes 20 to 26, wherein the at least one processor is configured to determine a total number of transmission points in a cell transmitting on the same second set of time and frequency resources or a total number of beams in a cell transmitted on the same second set of time and frequency resources based at least on a sequence of synchronization signals transmitted from the multiple transmission points on the same set of time and frequency resources. (Supplementary Note 28) The wireless terminal of any one of Supplementary Notes 20 to 26, wherein the at least one processor is configured to determine a total number of transmission points in a cell transmitting on the same second set of time and frequency resources or a total number of beams in a cell transmitted on the same second set of time and frequency resources based at least on a sequence of second demodulation reference signals transmitted from the multiple transmission points on the same set of time and frequency resources. (Supplementary Note 29) The wireless terminal of any one of Supplements 20 to 26, wherein the at least one processor is configured to determine a total number of transmission points in a cell transmitting on the same second set of time and frequency resources or a total number of beams in a cell transmitted on the same second set of time and frequency resources based at least on the Broadcast Channel payload. (Supplementary Note 30) The wireless terminal of any one of Supplementary Notes 20 to 26, wherein the at least one processor is configured to determine a total number of transmission points in a cell transmitting on the same second set of time and frequency resources or a total number of beams in a cell transmitted on the same second set of time and frequency resources based at least on configuration information in a System Information Block Type 1 (SIB1). (Supplementary Note 31) The wireless terminal of any one of Supplementary Notes 27 to 30, wherein the at least one processor is configured to identify a location within a resource grid of the individual first set of time and frequency resources based on a total number of transmission points within a cell transmitting on the same second set of time and frequency resources or a total number of beams within a cell transmitting on the same second set of time and frequency resources.(Supplementary Note 32) A method performed by a wireless terminal, comprising: receiving, in a first set of time and frequency resources individual for each transmission point, a first demodulation reference signal used to demodulate one of the same set of modulation symbols or different sets of modulation symbols generated from the same broadcast channel payload or different broadcast channel payloads; and receiving, in a second set of time and frequency resources common to multiple transmission points, the same set of modulation symbols or one of the different sets of modulation symbols. (Supplementary Note 33) A program comprising a plurality of instructions that, when executed by at least one processor of a wireless terminal, causes the wireless terminal to perform a method, the method comprising: controlling a Radio Frequency (RF) circuit of the wireless terminal to receive, in a first set of time and frequency resources individual for each transmission point, a first demodulation reference signal used to demodulate one of the same set of modulation symbols or different sets of modulation symbols generated from the same broadcast channel payload or different broadcast channel payloads; and controlling the RF circuit to receive, in a second set of time and frequency resources common to multiple transmission points, the same set of modulation symbols or one of the different sets of modulation symbols.(Supplementary Note 34) A wireless terminal comprising: a Radio Frequency (RF) circuit configured to communicate with a radio access network; and at least one processor coupled to the RF circuit, wherein the at least one processor is configured to: control the RF circuit to receive a demodulation reference signal used to demodulate a broadcast channel, wherein the demodulation reference signal is transmitted on a first set of time and frequency resources individually assigned to each transmission point, and the broadcast channel is transmitted on the same second set of time and frequency resources from multiple transmission points; and determine a portion of an identifier or index for distinguishing multiple beams or multiple synchronization signals and physical broadcast channel blocks transmitted from the multiple transmission points based at least on a position within a resource grid of the time and frequency resources at which the demodulation reference signal is received. (Supplementary Note 35) A method performed by a wireless terminal, comprising: receiving a demodulation reference signal used to demodulate a broadcast channel, wherein the demodulation reference signal is transmitted in a first set of time and frequency resources individually assigned to each transmission point, and the broadcast channel is transmitted from multiple transmission points in the same second set of time and frequency resources; and determining a portion of an identifier or index for distinguishing multiple beams or multiple synchronization signals and physical broadcast channel blocks transmitted from the multiple transmission points based at least on a position within a resource grid of the time and frequency resources at which the demodulation reference signal is received.(Supplementary Note 36) A program comprising a plurality of instructions that, when executed by at least one processor of a wireless terminal, causes the wireless terminal to perform a method, the method comprising: controlling a Radio Frequency (RF) circuit of the wireless terminal to receive a demodulation reference signal used to demodulate a broadcast channel, wherein the demodulation reference signal is transmitted on a first set of time and frequency resources individually assigned to each transmission point, and the broadcast channel is transmitted from multiple transmission points on the same second set of time and frequency resources; and determining a portion of an identifier or index for distinguishing multiple beams or multiple synchronization signals and physical broadcast channel blocks transmitted from the multiple transmission points based at least on a position within a resource grid of the time and frequency resources at which the demodulation reference signal is received. (Supplementary Note 37) A Distributed Unit (DU) of a base station, comprising: means for controlling a plurality of transmission points to transmit, in a first set of time and frequency resources that is individual for each transmission point, a first demodulation reference signal used to demodulate one of the same set or different sets of modulation symbols generated from the same broadcast channel payload or different broadcast channel payloads; and means for controlling the plurality of transmission points to transmit the same set of modulation symbols or the different sets of modulation symbols in a same set of second time and frequency resources.(Supplementary Note 38) A method performed by a Distributed Unit (DU) of a base station, comprising: controlling a plurality of transmission points to transmit, on a first set of time and frequency resources separate for each transmission point, a first demodulation reference signal used to demodulate one of the same set or different sets of modulation symbols generated from the same broadcast channel payload or different broadcast channel payloads; and controlling the plurality of transmission points to transmit the same set of modulation symbols or the different sets of modulation symbols on the same second set of time and frequency resources.

[0117] This application claims priority based on Japanese Patent Application No. 2022-143672, filed September 9, 2022, the disclosure of which is incorporated herein in its entirety.

[0118] 10 CU 21, 22 DU 31, 32, 33, 34, 35 TRP 40 UE 51, 52, 53 Cell 1602 Processor 1603 Memory 1704 Processor 1705 Memory 1803 Baseband processor 1804 Application processor 1806 Memory

Claims

1. Multiple transmission points; A baseband unit; Equipped with The baseband unit includes: controlling each of the plurality of transmission points to transmit, in a first set of time and frequency resources distinct for each transmission point, a first demodulation reference signal used to demodulate one of a same set or different sets of modulation symbols generated from a same broadcast channel payload or different broadcast channel payloads; controlling the plurality of transmission points to transmit the same set of modulation symbols or the different sets of modulation symbols on a same second set of time and frequency resources. It is configured as follows: Base station transmission system.

2. transmitting, from each of a plurality of transmission points, in a first set of time and frequency resources separate for each transmission point, a first demodulation reference signal used to demodulate one of the same set or different sets of modulation symbols generated from the same broadcast channel payload or different broadcast channel payloads; and transmitting the same set of modulation symbols or the different sets of modulation symbols from the multiple transmission points on a same second set of time and frequency resources; A method performed by a base station transmission system comprising:

3. a radio frequency (RF) circuit configured to communicate with a radio access network; means for controlling the RF circuitry to receive a first demodulation reference signal used to demodulate one of a same set or different sets of modulation symbols generated from a same broadcast channel payload or different broadcast channel payloads in a first set of time and frequency resources separate for each transmission point; means for controlling the RF circuitry to receive one of the same set of modulation symbols or the different sets of modulation symbols on a second set of time and frequency resources common to a plurality of transmission points; Equipped with Wireless terminal.

4. the first demodulation reference signal is used to demodulate a same set of the modulation symbols generated from the same broadcast channel payload; and means for controlling the RF circuitry to receive one of the same set of modulation symbols or the different set of modulation symbols controls the RF circuitry to receive the same set of modulation symbols in the common second set of time and frequency resources. It is configured as follows:

4. The wireless terminal of claim 3.

5. A means for estimating an individual channel response between each transmission point and the wireless terminal based on reception of the first demodulation reference signal; means for calculating a composite channel response using a plurality of individual channel responses between the plurality of transmission points and the wireless terminal; means for demodulating the same broadcast channel payload from the same set of modulation symbols using the composite channel response; Equipped with 5. The wireless terminal according to claim 4.

6. The method includes: determining an identifier or index for distinguishing between a plurality of beams or a plurality of synchronization signals and a physical broadcast channel block transmitted from the plurality of transmission points based at least on a location within a resource grid of the respective first set of time and frequency resources. The wireless terminal according to any one of claims 3 to 5.

7. The method includes: determining, based at least on a sequence of the first demodulation reference signals received on the respective first set of time and frequency resources, an identifier or index for distinguishing between a plurality of beams or a plurality of synchronization signals and a physical broadcast channel block transmitted from the plurality of transmission points. The wireless terminal according to any one of claims 3 to 5.

8. receiving, in a first set of time and frequency resources separate for each transmission point, a first demodulation reference signal used to demodulate one of the same set or different sets of modulation symbols generated from the same broadcast channel payload or different broadcast channel payloads; and receiving one of the same set of modulation symbols or the different sets of modulation symbols on a second set of time and frequency resources common to a plurality of transmission points; A method performed by a wireless terminal comprising:

9. a radio frequency (RF) circuit configured to communicate with a radio access network; means for controlling the RF circuitry to receive a demodulation reference signal used to demodulate a broadcast channel, wherein the demodulation reference signal is transmitted on a first set of time and frequency resources individually assigned to each transmission point, and the broadcast channel is transmitted on the same second set of time and frequency resources from a plurality of transmission points; determining a portion of an identifier or index for distinguishing between a plurality of beams or a plurality of synchronization signals and a physical broadcast channel block transmitted from the plurality of transmission points based at least on a position within a resource grid of time and frequency resources at which the demodulation reference signal is received; Equipped with Wireless terminal.

10. means for controlling a plurality of transmission points to transmit, on a first set of time and frequency resources separate for each transmission point, a first demodulation reference signal used to demodulate one of the same or different sets of modulation symbols generated from the same or different broadcast channel payloads; means for controlling the plurality of transmission points to transmit the same set of modulation symbols or different sets of modulation symbols on a same second set of time and frequency resources; A Distributed Unit (DU) of a base station.