SRS configuration communication

Abstract

Methods and apparatus for efficient SRS (Sounding Reference Signal) configuration communication in O-RAN networks are disclosed. An O-RAN Radio Unit (O-RU) receives messages from an O-RAN Distributed Unit (O-DU) describing SRS configurations for multiple User Equipment (UEs). The messages organize SRS allocation information using PRB (Physical Resource Block) clusters representing contiguous frequency ranges and SRS blocks combining clusters with OFDM symbols. The hierarchical message structure includes UE-level parameters such as capability identification, identity values, and SRS sequence information, along with port- level details including cyclic shifts and comb offsets. Section extensions provide flexibility for future parameter additions. This approach enables efficient fronthaul communication while supporting complex SRS multiplexing scenarios including frequency hopping and antenna switching. The O-RU performs SRS reception and channel estimation based on the received configuration, reducing processing load on the O-DU and fronthaul bandwidth in massive MIMO deployments.

Description

[0001] SRS CONFIGURATION COMMUNICATION

[0002] The present disclosure relates to the field of handling and use of Sounding Reference Signals, SRS.

[0003] BACKGROUND

[0004] Massive MIMO (Multiple Input Multiple Output) is one key technology in 4G, 5G and beyond, which are widely deployed globally. It features with a large number of antennas used on the base-station side, where the number of antennas is typically much larger than the number of user-layers, for example, 64 antennas serving 8 or 16 user-layers in frequency range 1 (FR1), which comprises sub-6 GHz frequency bands, and 256 / 512 antennas serving 2 or 4 layers in FR2, which comprises frequency bands from 24.25 GHz to 52.6 GHz. A user layer when used herein e.g., means an independent downlink or uplink data stream intended for one user. One user or UE may have one or multiple user layers. User layer is also referred to as layer, e.g., in 3GPP terminology. Massive MIMO is also referred to as massive beamforming, which is able to form narrow beams focusing on different directions to counteract against the increased path loss at higher frequency bands. It also benefits multi-user MIMO which allows for transmissions from / to multiple users simultaneously over separate spatial channels resolved by massive MIMO technologies nulling the interferences between users, while keeping high performance, e.g., throughput, for each user. Therefore, it can significantly increase the spectrum efficiency and cell capacity.

[0005] At the base-station side, the interface between the distributed unit (DU) and the radio unit (RU) is the fronthaul (FH) interface, as shown in Figure 1. The great benefits of massive MIMO at the air-interface also introduce new challenges at the base-station side. The legacy CPRI-type fronthaul transports time-domain IQ samples per antenna branch. As the number of antennas scales up in massive MIMO systems, the required fronthaul capacity also increases proportionally, which significantly drives up the fronthaul costs. To address this challenge, the fronthaul interface evolves from CPRI (Common Public Radio Interface) to eCPRI (Enhanced Common Public Radio Interface), a packet-based fronthaul interface. In eCPRI, other functional split options between a DU and a RU are supported, referred to as different lower- layer split (LLS) options. In the eCPRI standard specification, the terms eREC (eCPRI Radio Equipment Control) and eRE (eCPRI Radio Equipment) are used instead of DU and RU. The basic idea is to move the frequency-domain beamforming function from DU to RU so that frequency samples or data of user-layers are transported over the fronthaul interface. Note that the frequency-domain beamforming is sometimes also referred to as precoding in the downlink (DL) direction and equalizing or pre-equalizing in uplink (UL) direction. By doing this, the required fronthaul capacity and thereby the fronthaul costs are significantly reduced, as the number of user layers is typically much fewer than the number of antennas in massive MIMO. In O-RAN open fronthaul interface specification 0-RAN.WG4.CUS.0-R004-vl6.01DU is referred to as O-DU (O-RAN DU) while RU is referred to as O-RU (O-RAN RU). O- RAN.WG4.CUS.0-R004-vl6.01 was the current specification as of the earliest priority date and is hereinafter and above referred to as the current O-RAN open fronthaul specification [1],

[0006] Figure 2 shows the downlink (DL) Weight-based Dynamic Beamforming (WDBF) implementation supported by the current O-RAN WG4 specification [1], By having the DL beamforming function in the O-RU, the number of streams going through the fronthaul interface becomes the number of layers. The DL beamforming weights are calculated in the O- DU based on the SRS signal sent back from the O-RU.

[0007] Figure 3 shows the control-plane (C-plane) and user-plane (U-plane) data flow for WDBF in DL. For every slot, the O-DU sends first C-plane messages to convey the scheduling information to the O-RU. The scheduling information includes the REs (Resource Elements) to be scheduled, the beam ID (referred as beamld in the specification) which represents the beamforming weights stored in the O-RU, or the beamforming weights (BFWs) together with its beam ID to be used if not stored. Then, the O-DU sends the DL U-Plane data (IQ data after modulation which may be compressed) to the O-RU. The O-RU receives the scheduling information and the DL U-Plane data. Then, the O-RU processes the received IQ data according to the scheduling information received, e.g., perform beamforming (i.e., apply the beamforming weights received directly or indicated by the beam ID received), perform IFFT and add cyclic prefix, etc., to generate OFDM IQ data, send the OFDM IQ data to the DFE and RF-frontend, and send the OFDM signal out from the antennas. .

[0008] There is another type of beamforming methods defined in the current O-RAN WG4 specification, referred as Channel Information based Beamforming (CIBF). In CIBF, instead of transferring BFWs or beamld, the O-DU transfers to the O-RU the scheduled layers and the SRS channel estimates of the scheduled layers in the C-plane messages. The O-RU uses the received information (i.e., the scheduled REs, the scheduled layers and their channel estimates for the scheduled REs) to calculate the BFWs and perform beamforming to the received DL U- Plane data using the calculated BFWs.. In the specification, each scheduled layer is conveyed by a field called “ueld” in C-plane message. Although the field name is “ueld”, the ueld represents a layer, not a UE. For a UE with multiple layers scheduled, it needs multiple ueld(s) where each ueld represents one layer of the UE.

[0009] In the current O-RAN WG4 open-fronthaul CUS specification [1], O-RAN CU plane (control plane and user plane) distinguishes logical data flows on transport level, based on the eAxC ID presented in the eCPRI transport header of the C- and U-plane messages. It allows to distinguish RU’s logical flows, representing spatial streams (e.g. beamformed data stream), which are the layers when WDBF or CIBF is used.

[0010] In O-RAN open fronthaul, a C- or U-plane message contains an eCPRI transport header, in which the “ecpriRtcid / ecpriPcid” field represents the eAxC ID used. A C- or U-plane message further contains one or more sections using a specific Section Type. Multiple Section Types are defined to carry different types of scheduling information for different purposes. For example, Section Type 0 (STO) is used to represent unused resource blocks or symbols. Section Type 1 (STI) is used to represent used (scheduled) resource elements (REs) for most DL / UL channels, e.g., PUSCH (Physical Uplink Shared Channel), PDSCH (Physical Downlink Shared Channel), etc., when WDBF is used. Each section can be attached with one or more Section Extensions. Each Section Extension attached includes additional information than that described by the section. For example, Section Extension 1 (SEI) is used to provide beamforming weights. Section Extension 4 (SE4) is used to provide modulation compression parameters. Section Extension 10 (SE10) is used to provide beamforming weights or uelds when port (or layer) grouping is used.

[0011] There currently exist certain challenge(s).

[0012] One problem of WDBF and CIBF in the current O-RAN open fronthaul specification is that a large amount of SRS IQ data is sent from O-RU to O-DU over the fronthaul interface, which increases the fronthaul bit rate. In this case, O-RU sends the IQ data of the SRS symbols of all antennas to the O-DU. It means that the number of FH spatial streams for transporting SRS IQ data equal to the number of antennas, while the number of FH spatial streams for transporting IQ data of PUSCH data equal to the number of the beamformed streams or layers after beamforming in O-RU which is much less than the number of antennas. As a result, the amount of the SRS IQ data per symbol is much more than that of the IQ data of PUSCH data symbol. For example, for 64 antennas and 8 spatial streams or layers used for PUSCH, the IQ data of a fully loaded SRS symbol is 8 times more than that of a fully loaded PUSCH symbol. In O-RAN, this issue can be addressed by delaying sending SRS IQ data in DL slots. But this would cause longer delay and increase O-RU costs for data buffering.

[0013] Another problem is that the O-DU processing capacity is highly loaded by SRS processing. When one O-DU is connected to multiple O-RUs, the SRS is scheduled simultaneously across the network due to the time division duplex (TDD) pattern. All SRS IQ data from multiple O- RUs arriving at the DU at the same time. This imposes a significant processing load on the O- DU, as it must handle SRS for channel estimation from all O-RUs simultaneously. This significantly reduces the statistical multiplexing gain for O-DU processing, which assumes that the processing load from different RUs are not at the peak simultaneously. Given limited hardware resources in O-DU, this may significantly limit SRS processing capability, i.e., the number of users sending SRS, which limits the system capacity in terms of the number of served users which utilize SRS for scheduling and beamforming etc. Also, the simultaneous transmission of SRS samples from multiple RUs to a DU limits statistical multiplexing gain in fronthaul transport when fronthaul links are aggregated.

[0014] To further address these problems, O-RAN agrees to standardize a new functional split which moves SRS channel estimation function to the O-RU. It is currently referred to as SRS based beamforming (SRS-BF). Then SRS processing is offloaded to the O-RU, which could increase the O-DU capacity to process more antenna carriers and users.

[0015] Figure 4 shows one variant of SRS-BF implementation for DL. In this variant, both SRS channel estimation and DL beamforming weights calculation are moved to the O-RU. O-RU also calculates some SRS-based RRM (Radio Resource Management) measurements (e.g., time-offset, SINR (Signal to Interference plus Noise Ratio), signal power) and sends these measurements back to the O-DU. Further, O-RU sends SRS channel estimates back to the O- DU. The SRS channel estimates may be compressed to reduce the amount of data over fronthaul interface. Both SRS RRM measurements and SRS channel estimates are used by the O-DU for scheduling and other purposes. Since DL beamforming weights calculation are also moved to the O-RU, there is no beamforming weights transported over the fronthaul interface, which reduces the fronthaul bit rate in the direction from O-DU to O-RU. Figure 5 shows another variant of SRS-BF implementation for DL. In this variant, SRS channel estimation is moved to the O-RU while DL beamforming weights calculation is kept in the O-DU. In this variant, the O-DU can reuse most of functionalities in WDBF, which makes easier to migrate to SRS-BF. The main benefit is to offload the O-DU processing from SRS channel estimation.

[0016] In SRS-BF, the key is to perform SRS channel estimation in the O-RU. To enable this, the O- DU needs to provide SRS configuration information to the O-RU via C-Plane messages. After receiving the C-Plane message containing SRS configuration information, the O-RU can generate the corresponding SRS sequences and perform SRS channel estimation for each UE which sent the SRS signal.

[0017] In 3GPP, SRS can be sent in some symbols in the special slot which contains both DL and UL transmissions or an UL slot which only contains UL transmissions. SRS can be configured as periodic, aperiodic, or semi-periodic. Each UE is informed by the base station the SRS configuration which will be used by the UE to generate its SRS. The SRS of one UE can have multiple SRS ports if it has multiple antenna ports. One antenna port may be one physical antenna or a virtual antenna by beamforming with multiple antennas. Each SRS port corresponds to the SRS sent by one UE antenna port. The SRS ports of one or more UEs are allocated with orthogonal resources in frequency domain, time domain, or code domain. In frequency domain, different ports can use different Comb Offsets, i.e., using different resource elements (REs) in the same PRBs. They can also use different PRB ranges. In time domain, they can use different symbols. In code domain, they can use different Cyclic Shifts (CS) which makes the SRS sequence orthogonal. An SRS symbol can multiplex many SRS ports. For example, with full bandwidth sounding per UE, one SRS symbol can multiplex 48 SRS ports. With half bandwidth sounding per UE, one SRS symbol can multiplex 96 SRS ports. The number of SRS ports further increases when multiple SRS symbols are used, e.g., 2, 4, 6 SRS symbols. SRS also supports various features such as frequency hopping, repetition, antenna switching etc. It is also constrained by the UE capabilities such as 1T4R, 2T4R, 1T2R, bandwidth part, etc. Considering all these above, SRS resource multiplexing can be very complicated, much more complicated than DMRS (Demodulation Reference Signal) resources which only have a few ports and a few configurations. SUMMARY

[0018] The present disclosure provides solutions for efficient communication of Sounding Reference Signal (SRS) configuration information in O-RAN (Open Radio Access Network) systems. In massive MIMO deployments, there is a need to move SRS channel estimation functionality from the O-RAN Distributed Unit (O-DU) to the O-RAN Radio Unit (O-RU) to reduce fronthaul overhead and processing load. This requires the O-DU to communicate detailed SRS configuration information to the O-RU through control plane messages.

[0019] The disclosed technology introduces structured message formats that organize SRS configuration data hierarchically, using concepts of PRB (Physical Resource Block) clusters and SRS blocks to efficiently describe complex SRS resource allocations. A PRB cluster represents a contiguous frequency range of PRBs used by one or more UEs for SRS transmission, while an SRS block combines a PRB cluster with a specific OFDM symbol. This organization allows the O-RU to efficiently extract the necessary information for SRS sequence generation and channel estimation.

[0020] The solution supports various SRS multiplexing scenarios including frequency hopping, antenna switching, and different UE capabilities (such as 1T4R, 2T4R configurations). The message structure is designed to be fronthaul-efficient by minimizing redundant information and grouping related SRS configuration data together. Additionally, flexible section extension mechanisms are provided to allow future parameter additions without disrupting the core message structure.

[0021] Multiple message structure variants are disclosed, ranging from single comprehensive sections to distributed approaches with multiple smaller sections, providing implementation flexibility while maintaining compatibility with existing O-RAN protocol principles.

[0022] According to some aspects of the present disclosure, there is provided a method performed by an O-RAN Radio Unit (O-RU) comprising receiving a message for describing a sounding reference signal (SRS) configuration for a plurality of User Equipments (UEs). The message may be included in an O-RAN C-plane section description transmitted from an O-RAN O-DU to an O-RAN O-RU. The message describes the allocation of air interface resources to a plurality of UEs for sending SRS, and / or parameters required for SRS channel estimation, and indicates one or more clusters, where a cluster may be a contiguous range of physical resource blocks (PRBs) in the frequency dimension. The message may indicate for each of one or more clusters, the cluster's location and size in the frequency dimension, wherein the PRB range of the cluster is to be used for sending SRS from one or more UEs. The message may also indicate one or more symbols for sending SRS, the symbols being Orthogonal Frequency Division Multiplex (OFDM) symbols.

[0023] In some embodiments, the message may have a section part for each of one or more SRS blocks, where an SRS block may be defined by a PRB cluster and a symbol, in which the SRS sequences of one or more SRS ports of one or more UEs are multiplexed. Each SRS block section part may comprise for each UE a UE part, which may include indications such as a number of SRS ports used by the UE, an identification value indicating a capability of the UE, a UE identity value, whether the UE corresponding to the UE identity value has changed or not, and an SRS sequence identity value used by the UE to generate an SRS sequence.

[0024] The UE part may comprise an indication of SRS allocation for the UE for the symbol and the cluster, and may in some cases not comprise any indication of SRS allocation for any other UE. Each UE part may comprise for each UE SRS port an SRS port part, which may include indications of a cyclic shift, a comb offset, and a UE antenna port identity. The SRS port part may in some cases not contain any indication of SRS allocation for any other SRS port.

[0025] In some aspects, the identification value indicating a capability of the UE (ueCapId) may indicate a total number of physical antennas of the UE that can be used for communicating signals, or may indicate a number of transmitters of the UE for transmitting signals.

[0026] The message may comprise for one or more sections a first section extension part, where the first section extension part may comprise one or more second parts wherein each such second part comprises an indication of which third part of the message or section the second part of the section extension applies to. Each second part may comprise a type identifier that identifies which kinds of third parts the second part applies to, such as UE or UE port, and may further comprise one or more indications of which individual third parts of the kinds the second part applies to.

[0027] The O-RU may perform SRS reception and processing based on the SRS allocation described in the message, where SRS processing may comprise channel estimation. According to other aspects, there is provided an O-RU adapted to perform the above method, an apparatus for functioning as an O-RU comprising processing circuitry and a memory configured to perform the method, a computer program comprising program code which when run on an O-RU causes the O-RU to perform the method, and a tangible, non-transient computer-readable medium comprising instructions that, when executed by processing circuitry of an O-RU, cause the processing circuitry to perform the method.

[0028] According to further aspects, there is provided a method performed by an O-RAN Distributed Unit (O-DU) comprising transmitting to an O-RU the message as described above, along with corresponding O-DU apparatus, computer program, and computer-readable medium implementations.

[0029] BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 shows a block schematic of a fronthaul interface between RU and DU.

[0031] Figure 2 shows a block schematic of a DL WDBF implementation supported by the current O- RAN open fronthaul specification.

[0032] Figure 3 shows a block schematic of C-plane and U-plane data flows for DL in current O-RAN open fronthaul specification.

[0033] Figure 4 shows a block schematic of a first variant of SRS-BF functional split for DL.

[0034] Figure 5 shows a block schematic of a second variant of SRS-BF functional split for DL.

[0035] Figure 6 shows a diagram of an example of SRS configuration for 4 UEs.

[0036] Figure 7 shows a diagram of a second example of SRS configuration.

[0037] Figure 8 shows a diagram of a third example of SRS configuration.

[0038] Figure 9 shows an example of a communication system.

[0039] Figure 10 shows another example of a communication system.

[0040] Figure 11 shows a block schematic of a wireless device.

[0041] Figure 12 shows a block schematic of a network node. Figure 13 shows a block schematic illustrating a virtualization environment.

[0042] Figure 14 shows a diagram of an example of SRS configuration for 4 UEs.

[0043] Figure 15 shows a diagram of a second example of SRS configuration.

[0044] Figure 16 shows a diagram of a third example of SRS configuration.

[0045] DETAILED DESCRIPTION

[0046] The C-Plane SRS configuration description structure needs to be carefully designed to optimize for flexibility (supporting all possible resource multiplexing), O-RU processing efficiency (for O-RU to easily get the necessary information for generating SRS sequences) and FH efficiency (reduce the number of bytes used for SRS configuration description).

[0047] Certain aspects of the disclosure and their embodiments may provide solutions to these or other challenges.

[0048] In patent application PCT / SE2024 / 051026 previously filed, we proposed an efficient C-Plane message structure (Section Type ZZ) to describe the SRS configuration of all SRS ports in a slot containing SRS in one section description, if it is within the pay load size limit of the packet. If the message size is higher than the pay load size limit, it will split into multiple messages. The split is done on symbol level. Each message contains the SRS configuration description for a set of symbols. The proposed section description contains 5 levels of description, i.e., common level, symbol level, PRB cluster level, UE level, SRS port level. Common level contains the common information for all SRS ports in all symbols and the definition of cluster ID and symbol ID grid. And a PRB cluster is defined as a unique continuous PRB range used at least by one UE in any SRS symbol in the slot. Symbol level contains the common information for all SRS ports in each symbol identified by a symbol ID. PRB cluster level contains the common information for all SRS ports in each PRB cluster identified by a cluster ID in each symbol. UE level contains the common information for all SRS ports of each UE identified by an SRS UE ID in each cluster in each symbol. SRS port level contains the information for each SRS port identified by an SRS port ID of each UE in each cluster in each symbol. However, there is a challenge to support future extension, e.g., add new parameters in the future. In the current O-RAN open fronthaul specification, the section extension design can’t support the proposed 5-level section description structure. The current section extension design can only support one level. This would limit the extensibility of proposed section description. In this disclosure, we propose a new Section Extension design to solve this issue. The proposed new Section Extension can flexibly and efficiently add extension data to any part or level of the SRS description, e.g., to all symbols on common level, any specific symbol on symbol level, any specific SRS block on PRB cluster level, any specific UE on UE level, any specific UE SRS port on UE SRS port level.

[0049] Further, the original proposal in patent application PCT / SE2024 / 051026 supports one section description with multi-level structure. In this disclosure, we proposed two new message structures to support using multiple section descriptions. The multiple section descriptions describing the SRS configuration of all SRS ports in a slot containing SRS are contained in one message, if it is within the payload size limit of the packet. Otherwise, it will be split into multiple messages. One benefit for supporting multiple sections is that it is more straightforward to split sections to multiple sections when needed. This way is conceptually more compatible to the principle of the current O-RAN open fronthaul protocol design, while still keeping the benefits of the original proposal in patent application PCT / SE2024 / 051026. So, it may be more friendly to some HW implementation designed for current O-RAN specification. In the original proposal of patent application PCT / SE2024 / 051026, the rule to split on symbol level needs to be specified in the specification, which may be considered as adding complexity to the specification since it may be considered as adding one more implementation option. Another benefit is that the section extension can address smaller part of the SRS configuration in each section, which may be considered to be easier for some HW implementations.

[0050] In the first new proposal in this disclosure, we propose Section Type YY supporting multiple section descriptions with one section per symbol. Effectively, this proposal still maintains 5- level structure in the message. But the symbol level is done in sections. Then the section extension is done per symbol accordingly. This proposal aggregates SRS configuration per symbol in each section and using section extension can add new parameters to different part of the section. As mentioned before, advantage is that Section Type YY supporting multiple sections which are more compatible to the current O-RAN open fronthaul protocol design without the need to introducing a new implementation option, e.g., about message fragmentation when split a message to multiple messages. This contributes to a more consistent O-RAN specification and protocol handling, since O-RAN always support multiple sections. Introducing constraint to allow only 1 section description may be treated as non- backwards compatible. And some HW may prefer processing multiple smaller sections, instead of one large section. This proposal has one section per symbol. The number sections are usually not increase so much than Section Type ZZ.

[0051] In the second proposal in this disclosure, we create Section Type WW supporting multiple section descriptions with one section per SRS PRB block identified by symbol ID and cluster ID. It can be seen as merger of symbol level and PRB cluster level to one SRS block level. Note that in patent application PCT / SE2024 / 051026 SRS block is also referred as SRS resource. In this disclosure, we use SRS block as the terminology in addition to SRS resource. New section extension designs are also provided to support providing new parameters (extension data) in the future. This proposal aggregates SRS configuration per SRS block in each section and using section extension can add new parameters to different part of the section. This proposal allows even smaller sections than Section Type YY, at the cost of having more sections. This proposal may benefit some HW that prefers processing even smaller sections on PRB block level.

[0052] In all proposals, on UE level description, the parameter of srsUeld is used to identify the UE which sends the SRS and it is also used to identify the channel estimates of the UE estimated from the SRS. Then, when this UE is scheduled, O-DU will send a ueld corresponding to the srsUeld of this UE to O-RU to instruct the O-RU to calculate the beamforming weights for this UE using the corresponding channel estimates. Another parameter of srsSeqld on UE level is used to generate SRS sequence for SRS channel estimation. Further, the parameter of ueCapId indicates the UE capability for channel sounding using SRS regarding the number of UE antennas capable of transmitting data in UL and the number of UE antennas capable of receiving data in DL, which often referred to as xTyR, where y antennas is the number of antennas capable of receiving data in DL and x antennas among y antennas is the number of antennas capable of transmitting data in UL, where normally y>x. Note that the y antennas may be only a subset of the total number of antennas a UE has, as specified in 3GPP. It is UE that decides if it wants to use all antennas or a subset of all antennas for channel sounding using SRS. Each UE reports this UE capability for channel sounding to base station via RRC messages over air interface and O-DU extracts the UE capability information for each UE from RRC messages. O-DU will send the indication (e.g., ueCapId) of this UE capability for each UE to O-RU via an open-fronthaul C-Plane message for SRS configuration. To sound all y antennas, SRS are sent multiple times, and each time are sent from different x antennas among y antennas. This parameter is not directly used in the channel estimation algorithm. However, the benefit of having ueCapId (UE capability indication) is that the O-RU can use this information to better prepare the HW resources. For example, if O-RU knows the UE has capability of 1T4R from the first C-Plane section description that describes the first port of the UE, O-RU can infer that there will be totally 4 ports of SRS for this UE and there will be another 3 ports of SRS after the first port of SRS. In this example, the rest of 3 ports of SRS may be sent in next 3 SRS slots, e.g., using antenna switching. With this knowledge, O-RU can allocate the HW resources for processing 4 ports of SRS, e.g., allocating the memory to store 4 ports of SRS channel estimates, without the need for dynamically changing the memory size (e.g., memory re-allocation). Memory re-allocation takes quite some cycles that increases the processing delay. Another benefit is that it also helps the O-RU to know that the port information is complete when the number of ports received or read in section descriptions equals to the number of antennas capable of receiving data indicated by ueCapId. Then, O-RU can stop searching for this UE in the later section descriptions. Any processing involving using all UE ports can start immediately when the O-RU knows SRS sent from all ports are available. For example, doing port selection, port to layer mapping, determining rank, using the channel estimates of all UE ports.

[0053] Certain embodiments may provide one or more of the following and other technical advantage(s).

[0054] The new proposals (Section Type YY and Section Type WW) in this disclosure shares the same following advantages of Section Type ZZ proposed in patent application PCT / SE2024 / 051026, as listed below.

[0055] • The SRS configuration description structures of Section Type YY and Section Type WW are fronthaul efficient. It is more efficient that PRB range information is coded in cluster ID, instead of using two parameters of the start PRB and the end PRB, or the start PRB and the number of PRBs. Cluster ID uses much fewer bits than using two parameters. The appearances of symbol ID and cluster ID are minimized, which only appears on symbol level and cluster level, respectively.

[0056] • O-RU needs to know the configuration of all UE SRS ports in an SRS block in order to perform channel estimation. The proposed structures in Section Type YY and Section Type WW provide all UE SRS ports in a PRB cluster in a symbol together. So, O-RU can get the information efficiently after reading the description of a PRB cluster in a symbol. It doesn’t need to read further in the section description. So, it increases O-RU processing efficiency. In addition, the proposed new section extension design for Section Type ZZ proposed in patent application PCT / SE2024 / 051026 can flexibly and efficiently add extension data to any part of the SRS description, e.g., to all symbols on common level, any specific symbol on symbol level, any specific SRS block on PRB cluster level, any specific UE on UE level, any specific UE SRS port on UE SRS port level. It improves the extensibility of Section Type ZZ.

[0057] And the two new section structure proposed in this disclosure supports multiple sections in one message. It is more compatible to the principle of current O-RAN open fronthaul design supporting multiple sections, while still keeping most benefits of the original proposal in patent application PCT / SE2024 / 051026. It may be more friendly to some HW implementation designed for current O-RAN specification. It is more straight forward to split them into multiple messages when needed. It avoids adding one more implementation option in the specification, which makes the specification more consistent. It may be easier for some HW implementation, e.g. HW that prefers processing smaller sections.

[0058] Example of SRS configuration description

[0059] Figure 6 shows an example of SRS configuration for 4 UEs. In this example, each UE has to antenna ports. Two SRS symbols are used, i.e., symbol 10 and 11, in the slot. In frequency domain multiplexing, Comb 4 is used. Each UE uses half bandwidth with frequency hopping. It also shows the two PRB clusters according to the definition in the disclosure. There are two UEs in each PRB cluster in any symbol. Two antenna ports of a UE use two Cyclic Shifts of CS 0 and CS 6. In Figure 6, it shows in total 4 SRS blocks in this example. An SRS block is identified by a PRB cluster and a symbol, in which the SRS sequences of one or more SRS ports of one or more UEs are multiplexed. A PRB cluster is defined as a unique continuous PRB range used at least by one UE in any SRS symbol in the slot. Each PRB cluster is identified by a cluster ID. And Each symbol is identified by a symbol ID.

[0060] An SRS block represents the SRS data of the PRB range of a single SRS PRB cluster in a single symbol. In an SRS block, the SRS sequences of one or more SRS ports of one or more UEs are multiplexed. New Section Extension for 5-level section description (Section Type ZZ)

[0061] Table Al shows the format of new Section Extension XX defined to support adding more parameters to a section of Section Type ZZ proposed in patent application PCT / SE2024 / 051026. The proposed section extension provides the capability to add more parameters (referred to as extension data in Table Al to any part in a section of Section Type ZZ, e.g., to all symbols on common level, any specific symbol on symbol level, any specific SRS block on PRB cluster level, any specific UE on UE level, any specific UE SRS port on UE SRS port level. The section extension supports to provides extension data for multiple parts in a section of Section Type ZZ. Each part is referred to as one extension entry in Table Al. Each extension entry has fields of numExtensionEntry, srsExtensionType, srsUePortld, symbolld, srsClusterld, srsUeld and extension data.

[0062] Field of extension data represent the parameters of one entry the section extension conveys. numExtensionEntry represent the number of extension entries in this section extension. srsUePortld, symbolld, srsClusterld and srsUeld are identifier for UE SRS port, symbol, PRB cluster and UE. More detailed definitions of srsUePortld, symbolld, srsClusterld, srsUeld are provided in later description. These identifiers are used to identify different parts of the section description. But these identifiers are not always used. Field of srsExtensionType is used to indicate if and which these identifier(s) are used. When any identifier is not used, it may not be present in the structure to save some bytes in the section extension. The following lists an example of usage of srsExtensionType. Note that “reserved*” field in Table Al is only present if the other field in the same byte is present.

[0063] • srsExtensionType = 0: symbolld, srsClusterld, srsUeld, srsUePortld are not present, providing extension data for all symbols.

[0064] • srsExtensionType = 1 : symbolld is present, other IDs are not present, providing extension data for the symbol indicated by symbolld.

[0065] • srsExtensionType = 2: symbolld and srsClusterld are present, providing extension data for the SRS block indicated by symbolld and srsClusterld.

[0066] • srsExtensionType = 3: srsUeld is present, other IDs are not present, providing extension data for the UE indicated by srsUeld in all SRS blocks.

[0067] • srsExtensionType = 4: srsUeld and srsUePortld are present, other IDs are not present, providing extension data for the UE port indicated by srsUePortld of the UE indicated by srsUeld in all SRS blocks. • srsExtensionType = 5: symbolic!, srsClusterld and srsUeld are present, srsUePortld is not present, providing extension data for the UE indicated by srsUeld in the SRS block indicated by symbolld and srsClusterld.

[0068] • srsExtensionType = 6: symbolld, srsClusterld, srsUeld, srsUePortld are present, providing extension data for the UE port indicated by srsUePortld of the UE indicated by srsUeld in the SRS block indicated by symbolld and srsClusterld.

[0069] In this example, any unused identifier is not present to save some bytes. It is also possible to assign a special value to each identifier to indicate it is not used. This makes each entry with fixed structure which may benefit some HW implementation.

[0070] Table Al SRS configuration section extension structure (Section Extension XX) Section Type YY supporting multiple sections with one section per symbol

[0071] Table A2 shows the format of the new Section Type YY defined for the SRS configuration description supporting multiple sections with one section per symbol. The difference from Section Type ZZ in patent application PCT / SE2024 / 051026 is that the common level parameters are moved to the common header of Section Type YY which is applicable to all sections in the message, while Section Type ZZ has the common level parameters in the section header since it has only one section. Table A3 shows the section description format, in which each section provides the SRS configuration description of a symbol. Therefore, the symbol level descriptions can be described in multiple sections. Table A4, Table A5 and Table A6 show PRB cluster level SRS configuration description format, UE level SRS configuration description format, and SRS port level SRS configuration description format, respectively, for Section Type YY, which are the same as Section Type ZZ.

[0072] Table A2 SRS configuration description format (Section Type YY) Table A3 Section description format (symbol level SRS configuration description)

[0073] Table A4 PRB cluster level SRS configuration description format

[0074] Table A5 UE level SRS configuration description format

[0075] Table A6 SRS port level SRS configuration description format Section Extension AA for Section Type YY

[0076] Table A7 shows the format of new Section Extension AA defined to support adding more parameters to a section of Section Type YY. The design is similar to Section Extension XX. But each entry only has 3 identifier fields of srsUePortld, srsClusterld and srsUeld to identify different part of a section which provides SRS configuration description of a symbol. Field of srsExtensionType is used to indicate if and which these identifier(s) are used. When any identifier is not used, it may not be present in the structure to save some bytes in the section extension. The following lists an example of usage of srsExtensionType. Note that “reserved*” field in Table A7 is only present if the other field in the same byte is present.

[0077] • srsExtensionType = 0: srsClusterld, srsUeld, srsUePortld are not present, providing extension data for the referred symbol.

[0078] • srsExtensionType = 1 : srsClusterld are present, other IDs are not present, providing extension data for the SRS block indicated by srsClusterld in the referred symbol.

[0079] • srsExtensionType = 2: srsUeld is present, other IDs are not present, providing extension data for the UE indicated by srsUeld in the referred symbol.

[0080] • srsExtensionType = 3: srsUeld and srsUePortld are present, other IDs are not present, providing extension data for the UE port indicated by srsUePortld of the UE indicated by srsUeld in the referred symbol.

[0081] • srsExtensionType = 4: srsClusterld and srsUeld are present, srsUePortld is not present, providing extension data for the UE indicated by srsUeld in the SRS block indicated by symbolld and srsClusterld.

[0082] • srsExtensionType = 5: srsClusterld, srsUeld, srsUePortld are present, providing extension data for the UE port indicated by srsUePortld of the UE indicated by srsUeld in the SRS block indicated by srsClusterld in the referred symbol.

[0083] In this example, any unused identifier is not present to save some bytes. It is also possible to assign a special value to each identifier to indicate it is not used. This makes each entry with fixed structure which may benefit some HW implementation. Table A7 SRS configuration section extension structure (Section Extension AA)

[0084] Section Type WW supporting multiple sections with one section per SRS block

[0085] Table A8 shows the format of the new Section Type WW defined for the SRS configuration description supporting multiple sections with one section per SRS block. Table A9 shows the section description format, in which each section provides the SRS configuration description of an SRS block identified by a symbol ID (symbolld) and cluster ID (srsClusterld). Compared with Section Type ZZ and Section Type YY, this design can be seen as merger of symbol level and PRB cluster level to one SRS block level. Table A10 and Table Al l show UE level SRS configuration description format and SRS port level SRS configuration description format, respectively, for Section Type WW, which are the same as Section Type ZZ and Section Type YY.

[0086] Table A8 SRS configuration description format (Section Type WW) (next page) Table A9 Section description format (SRS block level SRS configuration description)

[0087] Table A10 UE level SRS configuration description format

[0088] Table All SRS port level SRS configuration description format

[0089] Section Extension BB for Section Type WW

[0090] Table A12 shows the format of new Section Extension BB defined to support adding more parameters to a section of Section Type WW. The design is similar to Section Extension XX and Section Extension AA. But each entry only has 2 identifier fields of srsUePortld, and srsUeld to identify different part of a section which provides SRS configuration description of aN SRS block. Field of srsExtensionType is used to indicate if and which these identifier(s) are used. When any identifier is not used, it may not be present in the structure to save some bytes in the section extension. The following lists an example of usage of srsExtensionType. Note that “reserved*” field in Table A12 is only present if the other field in the same byte is present.

[0091] • srsExtensionType = 0: srsUeld and srsUePortld are not present, providing extension data for the referred SRS block.

[0092] • srsExtensionType = 1 : srsClusterld are present, other IDs are not present, providing extension data for the SRS block indicated by srsClusterld in the referred symbol.

[0093] • srsExtensionType = 2: srsUeld is present, other IDs are not present, providing extension data for the UE indicated by srsUeld in the referred symbol.

[0094] • srsExtensionType = 3: srsUeld and srsUePortld are present, other IDs are not present, providing extension data for the UE port indicated by srsUePortld of the UE indicated by srsUeld in the referred symbol.

[0095] • srsExtensionType = 4: srsClusterld and srsUeld are present, srsUePortld is not present, providing extension data for the UE indicated by srsUeld in the SRS block indicated by symbolld and srsClusterld.

[0096] • srsExtensionType = 5: srsClusterld, srsUeld, srsUePortld are present, providing extension data for the UE port indicated by srsUePortld of the UE indicated by srsUeld in the SRS block indicated by srsClusterld in the referred symbol.

[0097] Table A12 SRS configuration section extension structure (Section Extension BB)

[0098] In this example, any unused identifier is not present to save some bytes. It is also possible to assign a special value to each identifier to indicate it is not used. This makes each entry with fixed structure which may benefit some HW implementation.

[0099] List of parameter fields used in this disclosure

[0100] The following lists the definitions of all parameter fields used in this disclosure, used in Table Al to Table A12.

[0101] • srsChestCompHdr: this field instructs how the O-RU will compress the channel estimates. For example, this field value indicates which compression method is used and how many bits are used to represent the channel estimates. The definition can be similar to ‘udCompHdr’ field for U-Plane data compression defined in O-RAN open fronthaul spec.

[0102] • numSrsCfgMsgs: the number of C-Plane messages that conveys the SRS configuration description of all SRS ports in the slot. This is useful when the section description for SRS configuration is so long that the number of bytes used in the C-Plane message is more than the maximum pay load size of a packet, e.g., 1500 bytes. In this case, the SRS configuration description is split into two or more C-Plane messages. With this field, the O-RU will know the number of C-Plane messages expected when receive the first C-Plane message.

[0103] • startSrsPrb: the PRB index of the first (lowest frequency) PRB that contains SRS in any SRS symbol in the slot described in this section description.

[0104] • numSrsPrb: the number of SRS PRBs of the continuous PRB range that contains SRS in any SRS symbol in the slot. It equals to endSrsPrb minus startSrsPrb plus one, where endSrsPrb represents the PRB number of the last (highest frequency) PRB that contains SRS in any SRS symbol in the slot. Alternatively, this field can be changed to endSrsPrb.

[0105] • numSrsSymbols: the total number of SRS symbols in the slot.

[0106] • numSrsClusters: the total number of SRS PRB clusters in the slot.

[0107] • srsClusterld: an identification value assigned to a PRB cluster. For example, srsClusterld = 0 for the first PRB cluster with lowest SRS frequency PRB.

[0108] • extrapolation: a one-bit flag to instruct O-RU to perform frequency-domain extrapolation in SRS channel estimation or not. If extrapolation is set to 1, the O-DU instructs the O-RU to perform frequency-domain extrapolation. If extrapolation is set to 0, the O-RU doesn’t need to do frequency-domain extrapolation.

[0109] • startPrbOfCluster: the PRB index of the first (lowest frequency) PRB of the referred SRS PRB cluster in a symbol.

[0110] • numPrbOfCluster: the number of PRBs of the referred SRS PRB cluster in a symbol.

[0111] • symbolld: an identification value representing a symbol in the slot. For example, symbolld = 0 for the first symbol in a slot and symbolld = 13 for the last symbol in a slot.

[0112] • numSrsUesOfSymbol: the total number of UEs sending SRS in the referred symbol.

[0113] • srsCombNum: Comb number for SRS used for all SRS in the referred symbol. Comb number indicates the subcarrier separation between two adjust subcarriers allocated for the SRS, as defined in 3GPP. • srsGroupSeqHopping: a value indicates the type of SRS symbol hopping used. There are several types, e.g., ‘neither’, ‘groupHopping’, or ‘sequenceHopping’ etc., as defined in 3GPP.

[0114] • numSrsPortsOfUe: the number of SRS antenna ports of the referred UE in the referred SRS resource identified by a srsClusterld and a symbolld.

[0115] • ueCapId: UE capability identification value indicates the capability of the referred UE. The UE capabilities are 1T1R, 1T2R, 1T4R, 2T2R, 2T4R, 4T4R, etc., where xTyR means y antennas capable of receiving data and x antennas among y antennas capable of transmitting data , where normally y>x. This capability is the UE capability concerning channel sounding using SRS. As explained before, the y antennas may not be all antennas a UE has. To sound the channel of all y antennas, SRS are sent multiple times, and each time are sent from different x antennas among y antennas. So, ueCapId is an indication for UE capability regarding UE transmit and receive capability. Each capability such as 1T1R, 1T2R, etc., may be assigned to a ueCapId value. The ueCapId may be indexed to indicate each capability in a list of all supported capabilities in 3GPP, which will save number of bits. An alternative is to have two subfields in the field of ueCapId. One subfield indicates x antennas among y antennas capable of transmitting SRS data, and the other subfield indicates y antennas capable of receiving data, each of which can be used to send SRS data as well. The number of UE antennas supported in 3GPP is in a limited set, e.g., 1, 2, 4, 8, 12, 16, 24, 32, etc. The indication of number of UE antennas can be indexed to indicate the number of antennas in the set, to save the number of bits for the indication. These two subfields may be explicitly expressed as two separate fields (parameters), e.g., called ueSrsTxCapId and ueSrsRxCapId, respectively. One more alternative is that the ueCapId (indication of UE capability) may only indicate the UE receive capability, i.e., yR (the number of antennas capable of receiving data), since another proposed field numSrsPortsOfUe may indicate xT (the number of antennas capable of transmiting data) as well. In this case, ueCapId may be called ueSrsRxCapId.

[0116] • srsUeld: an identification value assigned to a UE that sends SRS.

[0117] • srsUeldReset: a one-bit flag indicates if the srsUeld assignment to a UE is changed. For example, srsUeldReset = 1 indicates the srsUeld assignment is changed and srsUeldReset = 0 indicates the srsUeld assignment is unchanged. This helps the O-RU to use the historical channel estimates or measurements to calculate new measurements with higher quality.

[0118] • srsSeqld: SRS sequence identity value used to generate SRS sequence, as defined in 3GPP.

[0119] • srsUePortld: an identification value assigned to a UE SRS antenna port.

[0120] • srsCyclicShift: cyclic shift offset value indicates the cyclic shift applied to the SRS sequence for a UE SRS antenna port, as defined in 3GPP.

[0121] • srsCombOffset: comb offset value indicates a frequency offset within the comb used for a UE SRS antenna port, as defined in 3GPP.

[0122] • numExtensionEntry: number of extension entries in the section extension.

[0123] Some more examples of SRS configuration use cases

[0124] To further make it clear about the Cluster ID and Symbol ID mapping to SRS resources, more SRS configuration use case examples are provided here. Figure 7 shows an example with 4 SRS blocks with two PRB clusters and two symbols. In each SRS block, one or more UE SRS ports from one or more UEs can be allocated. In this example, numSrsSymbols = 2 and numSrsClusters = 2. The first PRB cluster refers full bandwidth SRS blocks, spanning from PRB 0 to PRB 271. The second PRB cluster refers half bandwidth SRS blocks, spanning from PRB 136 to PRB 271. In this example, two full bandwidth SRS blocks (marked as grey boxes) or the two half bandwidth SRS blocks (marked as white boxes) in Figure 7 may be used by a UE to send multiple SRS ports from multiple UE antennas using antenna switching. For example, a 2T4R UE sends SRS from first two UE antennas in symbol 10 and then the UE switches to the second two UE antennas to send SRS in symbol 12. In this example, symbol 11 is not used because antenna switching operation takes time and can’t be done for two adjacent symbols. In this example, the 4 SRS blocks can be efficiently described with only 2 symbol IDs and 2 cluster IDs.

[0125] Figure 8 shows another example with a more complicated SRS configuration. In this example, there are 9 SRS blocks marked as different boxes in Figure 8. Following the PRB cluster definition described in this document, there are 7 PRB clusters. First PRB cluster spans from PRB 0 to PRB 135. Second PRB cluster spans from PRB 136 to PRB 203. Third PRB cluster spans from PRB 204 to PRB 271. Fourth PRB cluster spans from PRB 0 to PRB 67. Fifth PRB cluster spans from PRB 68 to PRB 135. Sixth PRB cluster spans from PRB 136 to PRB 271. Seventh PRB cluster spans from PRB 0 to PRB 271. In this example, 9 SRS blocks can be efficiently described with only 4 symbol IDs and 7 cluster IDs.

[0126] Through the example shown previously, the proposed way of describing SRS configuration in one or multiple sections in C-Plane can efficiently describe all possible SRS configurations from simple cases to complicated cases in a well-structured way. And the SRS configuration of multiple SRS ports of one or more UEs in the same SRS block of each symbol are placed together in the C-Plane message. The O-RU can extract the SRS configuration efficiently for each SRS block identified by a cluster ID and a symbol ID, which facilitate channel estimation operation that are normally performed within an SRS block with the knowledge regarding how SRS is multiplexed in the SRS block. For example, this would become more complicated if the SRS configuration is provided UE by UE, which would have lower O-RU processing efficiency since O-RU has to identify the SRS blocks and the multiplexed UE ports in each SRS block by gathering information from multiple places describing different UEs in the message.

[0127] Embodiment adding cyclic shift resource information to assist channel estimation

[0128] In this embodiment, the information of the cyclic shift resources for estimating the channel of an antenna port may be included in the Section Type designed for conveying SRS configuration in C-Plane. The included information typically represents the relationship between cyclic shifts used by different antenna ports (may belong to one UE or different UEs) in each comb offset. With such information proposed in this embodiment, channel estimation of each antenna port only needs to read the port-level description of each individual antenna port without the need to read the portlevel descriptions of other ports. Without adding such information, O-RU may need to read through the port-level descriptions of all ports described in the section description and collect the information of cyclic shifts used by all antenna ports in each comb offset to understand the relationship between cyclic shifts in each comb offset and then perform channel estimation for the antenna port of each cyclic shift. Therefore, the proposal in this embodiment makes it easier for O-RU to perform channel estimation.

[0129] The SRS antenna ports in one comb offset use the same REs. They are code-division multiplexed. In order to efficiently separate them with good channel estimation quality of each port, each antenna port is assigned with different cyclic shift. The higher difference or longer distance in a cyclic way between two cyclic shifts used by two antenna ports, the more orthogonal the two antenna ports are. Basically, using the cyclic shift difference or distance between antenna ports using adjacent cyclic shifts can help identify the range of cyclic shifts used for channel estimation of one antenna port. Channel estimation algorithms typically use a range of cyclic shifts to estimate the channel of each antenna port. Basically, different cyclic shifts provide different time delay for different antenna ports, which makes it possible to separate the channel estimates of different antenna ports in time domain. Basically, large cyclic shift number results in longer delay. As an example for channel estimation, O-RU may first perform matched filtering that multiplies the received SRS IQ data with the generated SRS IQ samples and obtain the raw channel estimates. Then, the raw channel estimates are transformed to time domain samples, e.g., using DFT or other transforms, which correspond to channel impulse response. Since the channel impulse responses of different antenna ports are delayed differently, performing time domain filtering can filter out the negative contributions from other ports with different delays according to the determined range of cyclic shifts based on the cyclic shift distances between adjacent cyclic shifts and therefore improve channel estimation quality. For example, assuming Comb-4 with 12 cyclic shifts and there are two antenna ports, the first antenna port uses CS-0 and the second antenna port uses CS-3. For first antenna port, the time domain filtering will keep the samples in the time range corresponding to the range of CS-0 to CS-2 which contains the main energy of the first antenna port and remove the samples out of the range, since the samples out of the range contain noise and the energy from the second port that interferes the first antenna port. For the second port, the time domain filtering will keep the samples in the time range corresponding to the range of CS-3 to CS-11 which contains the main energy of the second port and remove the samples out of the range, since the samples out of the range contain noise and the energy from the first port that interferes the second antenna port. For both antenna ports, the interference and noise are reduced. This part of processing is normally referred to as noise suppression. To get back the frequency domain channel estimates, the filtered time domain samples are transformed back to frequency domain with much better quality than the raw channel estimates produced by matched filtering. Therefore, knowing the cyclic shift distances between adjacent cyclic shifts is of great help for channel estimation.

[0130] Some channel estimation algorithms for estimating the channel of an antenna port using a cyclic shift may use the offset to the next cyclic shift used by a different antenna port in the same comb offset to identify the range of the cyclic shifts used for channel estimation. Some channel estimation algorithms may use the offset to the nearest cyclic shift used by a different antenna port in the same comb offset to identify the range of the cyclic shifts used for channel estimation. The offset to the nearest cyclic shift is equal to the smaller offset of the offset to the next cyclic shift and the offset to the previous cyclic shift. Some channel estimation algorithms may use the offset to the next cyclic shift used by a different antenna port and the offset to the previous cyclic shift used by another different antenna port to identify the range of the cyclic shifts used for channel estimation. For example, having both the offset to the next cyclic shift and the offset to the previous cyclic shift can support algorithms that use the offset to the next cyclic shift and the algorithms that use the offset to the nearest cyclic shift. If there are only two cyclic shifts used, the previous and next cyclic shifts of one cyclic shift is the same cyclic shift used by one antenna port since the offset of cyclic shift is cyclically or circularly counted. In a special case, if there is only one cyclic shift used, the offset to the previous cyclic shift and the offset to the next cyclic shift equal to 0. Note that cyclic shift offset may also referred to as cyclic shift distance or cyclic shift difference. To illustrate with examples, we assume Comb-4 with 4 comb offsets is used. Following 3 GPP specification, each comb offset will have 12 cyclic shifts (CS). In example Cl, there are 3 antenna ports using CS-0, CS-3 and CS-9, respectively. Table Bl l shows the offset to the previous cyclic shift, the offset to the next cyclic shift and the offset to the nearest cyclic shift for each cyclic shift in this example. Table B12 shows example C2 assuming 4 antenna ports using CS-0, CS-3, CS-6 and CS-9, respectively. Table B13 shows example C3 assuming 2 antenna ports using CS-0 and CS-3, respectively. Table B14 shows example C4, assume 1 antenna port using CS-0.

[0131] Table Bll Example Cl: 3 antenna ports using CS-0, CS-3 and CS-9, respectively Table B12 Example C2: 4 antenna ports using CS-0, CS-3, CS-6 and CS-9, respectively

[0132] Table B13 Example C3: 2 antenna ports using CS-0 and CS-3, respectively

[0133] Table B14 Example C4: 1 antenna port using CS-0

[0134] Table B15 shows an example of port-level description with the added information of the offset to the next cyclic shift (offsetToNextCyclicShift) in Octet 2.

[0135] Table B15 port-level description with the offset to the next cyclic shift

[0136] Table B16 shows an example of port-level description with the added information of the offset to the nearest cyclic shift (offsetToNearestCyclicShift) in Octet 2. Table B16 port-level description with the offset to the nearest cyclic shift

[0137] Table B17 shows an example of port-level description with the added information of the offset to the next cyclic shift (offsetToNextCyclicShift) in Octet 2 and the offset to the previous cyclic shift

[0138] (offsetToPreviousCyclicShift) in Octet 3. Note that these two offset may be possible to be coded more efficiently as one field to save bits.

[0139] Table B17 port-level description with the offset to the nearest cyclic shift

[0140] As alternative of the offset to the nearest cyclic shift per cyclic shift in each comb offset, it is possible to include minimum offset to the nearest cyclic shifts for all cyclic shifts in each comb offset. In this case, O-RU will use the minimum offset value to determine the range of the cyclic shift for channel estimation for this antenna port. Though the minimum offset may be smaller than the actual offset to the nearest cyclic shifts for some antenna ports, it makes sure that the determined range has small negative contribution from other antenna ports. Table B18 shows an example with adding a field indicating minimum offset to the nearest cyclic shifts for all cyclic shifts (minOffsetToNearestCyclicShift) in each comb offset in the SRS block level description, e.g., in the section header. For example, Octet 6 contain the information of minimum offset to the nearest cyclic shifts in the first comb offset used. Table B18 SRS-block level description with minimum offset to the nearest cyclic shifts

[0141] Alternatively, minimum offset to the nearest cyclic shifts for all cyclic shifts in a comb offset (minOffsetToNearestCyclicShift) can be included in the port-level description, as exemplified in Table Bl 9.

[0142] Table B19 port-level description with minimum offset to the nearest cyclic shifts

[0143] The minimum offset to the nearest cyclic shifts may indicate the range of the cyclic shift that can be used to estimate the channel for the antenna port of this cyclic shift. So, this field may be formulated as the range of the cyclic shift or number of cyclic shifts to be used for estimating the channel for the antenna port of this cyclic shift. So, O-DU can set this field to tell O-RU the number of cyclic shifts to be used for channel estimation per port.

[0144] Table B15-B19 provides the examples to identify the range of the cyclic shifts used for channel estimation using different options of cyclic shift offset between antenna ports. Alternatively, it may be good for O-DU to indicate explicitly the range of the cyclic shifts used for channel estimation. Table B20 shows an example of port-level description with the added information of cyclic shift offset (expressed as a number of cyclic shifts) to be used for channel estimation (numCyclicShiftsForChest) in Octet 2. Table B21 show an example with the added information of cyclic shift offset to be used for channel estimation (numCyclicShiftsForChest) in each comb offset in the SRS block level description, e.g., in the section header. This is useful if the same cyclic shift offset to be used for channel estimation is used for all antenna ports with different cyclic shifts in each comb offset.

[0145] Table B20 port-level description with number of cyclic shifts for channel estimation

[0146] Table B21 SRS-block level description with number of cyclic shifts for channel estimation

[0147] Another possibility is to add information of the number of cyclic shifts used in each comb offset in port level description or SRS-block level description to identify the range of the cyclic shifts used for channel estimation. In this case, certain cyclic shift pattern needs to be assumed. For example, both O-RU and O-DU may assume that the cyclic shifts used by multiple cyclic shifts are equal distanced. So, O-RU can derive the range of the cyclic shifts used for channel estimation.

[0148] If multiple options are supported, selecting one option to use can be done via M-Plane (Management Plane). For example, O-RU declares supported options and O-DU configures to use one option among the O-RU supported options. If O-DU wants to use multiple options in run time, a field indicating which option to use should be added in the C-Plane section description.

[0149] Note that instead of being included in the Section Type design exemplified above, some fields may be included in a Section Extension used together with Section Type. In this case, both Section Type and Section Extension may be used to convey SRS configuration from O-DU to O-RU Also note that in the above exemplified embodiments, the PRB range of each SRS block may be indicated by a Cluster ID. Alternatively, the PRB range may be explicitly indicated in each section description. For example, the PRB range is indicated by a field of start PRB and a field of number of PRB in existing Section Types in current O-RAN specification.

[0150] Figure 9 shows an example of a communication system 900 in accordance with some embodiments.

[0151] In the example, the communication system 900 includes a telecommunications network 902 that includes an access network 904, such as a radio access network (RAN), and a core network 906, which includes one or more core network nodes 908. The access network 904 includes one or more access network nodes or base stations of various types, access network nodes 910A and 910B are depicted (which may be collectively referred to as network nodes 910), or any other similar 3rd Generation Partnership Project (3GPP) access nodes or non-3GPP access points (APs). Some embodiments of the access network 904 may include more than one access network technology. The network nodes 910 of access network 904 facilitate direct or indirect connection of wireless devices, also referred to as user equipments (UEs), such as by connecting UEs 912A, 912B, 912C, and 912D (one or more of which may be generally referred to as UEs 912) to the core network 906 over one or more wireless connections.

[0152] Moreover, a network node is not necessarily limited to an implementation in which a radio portion and a baseband portion are supplied and integrated by a single vendor. Thus, it will be understood that network nodes include disaggregated implementations or portions thereof. For example, in some embodiments, the telecommunications network 902 includes one or more Open- RAN (ORAN) network nodes. An ORAN network node is a network node in the telecommunications network 902 that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operate alone or together with other network nodes to implement one or more functionalities of any network node in the telecommunications network 902, including one or more access network nodes 910 and / or core network nodes 908.

[0153] Examples of an ORAN network node include an open radio unit (O-RU), an open distributed unit (O-DU), an open central unit (O-CU), including an O-CU control plane (O-CU- CP) or an O-CU user plane (O-CU-UP), a RAN intelligent controller (near-real time or non-real time) hosting software or software plug-ins, such as a near-real time control application (e.g., xApp) or anon-real time control application (e.g., rApp), or any combination thereof (the adjective “open” designating support of an ORAN specification). An ORAN network node may support a specification by, for example, supporting an interface defined by the ORAN specification, such as an Al, Fl, Wl, El, E2, X2, Xn interface, an open fronthaul user plane interface, or an open fronthaul management plane interface. Moreover, an ORAN network node may be a logical node in a physical node. Furthermore, an ORAN network node may be implemented in a virtualization environment (described further below) in which one or more network functions are virtualized. For example, the virtualization environment may include an O-Cloud computing platform orchestrated by a Service Management and Orchestration Framework via an 0-2 interface defined by the 0-RAN Alliance or comparable technologies. For example, the 0-DU can be implemented as virtualized 0-DU in a Cloud environment.

[0154] The network nodes 910 facilitate direct or indirect connection of one or more UEs 912 to the core network 906 over one or more wireless connections. Example wireless communications over a wireless connection include transmitting and / or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and / or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, the communication system 900 may include any number of wired or wireless networks, network nodes, UEs, and / or any other components or systems that may facilitate or participate in the communication of data and / or signals whether via wired or wireless connections. The communication system 900 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.

[0155] The UEs 912 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and / or operable to communicate wirelessly with the network nodes 910 and other communication devices. Similarly, the network nodes 908, 910 are arranged, capable, configured, and / or operable to communicate directly or indirectly (e.g., via other devices of telecommunications network 902) with the UEs 912 and / or with other network nodes or equipment in the telecommunications network 902 to enable and / or provide network access, such as wireless network access, and / or to perform other functions, such as administration in the telecommunications network 902. More specifically, UEs 912 may send messages, data, and / or other signals to network nodes 908, 910 or other elements of the telecommunications network 902 by transmitting such signals to the relevant device directly without the signals passing through any intervening devices or by transmitting such signals to the relevant device indirectly through an intervening device (or multiple intervening devices) that then transmit the signal to the relevant device. Similarly, network nodes 908, 910 may send messages, data, and other signals to UEs 9122, other network nodes 908, 910, and other devices in telecommunications network 902 directly or indirectly. As one specific example, a core network node 108 may transmit a particular message to a UE 912 by transmitting the message to an access network node 910 that will then transmit the message to the intended UE 912. Similarly, a core network node 108 may receive a particular message from a UE 912 by receiving the message from an access network node 910 that itself received the message from the UE 912.

[0156] In the depicted example, the core network 906 connects elements of the access network 904 (e.g., one or more of the network nodes 910) to one or more host computing systems, such as host 916. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. The core network 906 includes one or more core network nodes (e.g., core network node 908) of various types, one or more of which may be generally referred to as network nodes 908. Network nodes 908 are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the UEs, access network nodes, and / or hosts, such that the descriptions thereof are generally applicable to the corresponding components of the core network node 908. Example core network nodes provide functions of one or more of a Mobile Switching Center (MSC), Mobility Management Entity (MME), Home Subscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (SMF), Authentication Server Function (AUSF), Subscription Identifier De-concealing function (SIDF), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), and / or a User Plane Function (UPF).

[0157] The host 916 may be under the ownership or control of a service provider other than an operator or provider of the access network 904 and / or the telecommunications network 902. The host 916 may be operated by the service provider or on behalf of the service provider. The host 916 may host a variety of applications to provide one or more service. Examples of such applications include live and pre-recorded audio / video content, data collection services such as retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server.

[0158] As a whole, the communication system 900 of Figure 9 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system 900 may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and / or other suitable 2G, 3G, 4G, 5G standards, or any applicable future generation standard (e.g., 6G); wireless local area network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (Wi-Fi); and / or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (Wi-Max), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, Li-Fi, and / or any low-power wide-area network (LPWAN) standards such as LoRa and Sigfox. Moreover, the communication system 900 may be configured to support multiple different standards, protocols, or other rule sets, with individual components supporting all of the relevant rule sets or with different components or sub-systems within the communication system 900 supporting different standards, protocols, or rule sets.

[0159] As one example, in certain embodiments, access network 904 may contain some access network nodes 910 that support 3GPP radio access technologies (RAT), such as LTE or NR, while other access network nodes 910 support (or the same access network nodes 910 additionally support) non-3GPP RATs, such as Wi-Fi or a proprietary RAT. As another example, telecommunications network 902 may support multiple generations of related communication standards (e.g., 4G and 5G 3GPP communication standards) and, as a result, may include an access network 104 and / or a core network 106 that supports multiple different standard generations or may include multiple access networks 104 and / or multiple core networks 106 with individual networks 104, 106 supporting different standard generations.

[0160] Telecommunications network 902 may support network slicing to provide different logical networks to different devices that are connected to the telecommunications network 902. For example, the telecommunications network 902 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing Enhanced Mobile Broadband (eMBB) services to other UEs, and / or Massive Machine Type Communication (mMTC) / Massive loT services to yet further UEs.

[0161] In some examples, one or more of the UEs 912 are configured to transmit and / or receive information without direct human interaction. For instance, a UE may be designed to transmit information to the access network 904 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 904. Additionally, a UE may be configured for operating in single- or multi-RAT or multi-standard mode. For example, a UE may operate with any one or combination of Wi-Fi, NR (New Radio) and LTE, i.e. being configured for multi-radio dual connectivity (MR-DC), such as E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) New Radio - Dual Connectivity (EN-DC).

[0162] In the example, the hub 914 communicates with the access network 904 to facilitate indirect communication between one or more UEs (e.g., UE 912C and / or 912D) and network nodes (e.g., network node 910B). In some examples, the hub 914 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub 914 may be a broadband router enabling access to the core network 906 for the UEs. As another example, the hub 914 may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, network nodes 910, or by executable code, script, process, or other instructions in the hub 914.

[0163] As another example, the hub 914 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, the hub 914 may be a content source. For example, for aUE that is a VRheadset, display, loudspeaker or other media delivery device, the hub 914 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 914 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, the hub 914 acts as a proxy server or orchestrator for the UEs, in particular if one or more of the UEs are low energy loT devices.

[0164] The hub 914 may have a constant / persistent or intermittent connection to the network node 910B. The hub 914 may also allow for a different communication scheme and / or schedule between the hub 914 and UEs (e.g., UE 912C and / or 912D), and between the hub 914 and the core network 906. In other examples, the hub 914 is connected to the core network 906 and / or one or more UEs via a wired connection. Moreover, the hub 914 may be configured to connect to an M2M service provider over the access network 904 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 910 while still connected via the hub 914 via a wired or wireless connection. In some embodiments, the hub 914 may be a dedicated hub - that is, a hub whose primary function is to route communications to / from the UEs from / to the network node 910B. In other embodiments, the hub 914 may be a nondedicated hub - that is, a device which is capable of operating to route communications between the UEs and network node 910B, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0165] Figure 10 is another example of a communication system 1000 according to some embodiments. As used herein, the communication system 1000 includes multiple access points (APs) 1010 (with four exemplary APs 1010A, 1010B, 1010C, and 1010D being depicted) and multiple wireless devices, referred to in the context of communication system 1000 as stations (STAs) 1012 (referred to individually as STA 1012A, STA 1012B, STA 1012C, STA 1012D, and STA 1012E). STA 1012A is served by AP 1010A in a first basic service set (BSS) 1020A. STA 1010B and STA 1010C are served by AP 1010B in a second BSS, BSS 1020B. STA 1012D is served by AP 1010C in a third BSS, BSS 1020C. STA 1012E is served by AP 1010D in a fourth BSS, BSS 1020D. Stations 1012 may be non- AP STAs and correspond to various kinds ofwireless devices, for example, user terminals, such as mobile or stationary computing devices like smartphones, laptop computers, desktop computers, tablet computers, gaming devices, head- mounted displays (HMDs) for Augmented Reality (AR) or Virtual Reality (VR), or the like. Further, stations 1012 could, for example, correspond to other kinds of equipment like smart home devices, printers, multimedia devices, data storage devices, or the like.

[0166] Each of STAs 1012 may connect through a radio link to one of APs 1010. For example, depending on location or channel conditions experienced by a given STA 1012, the STA may select an appropriate AP and BSS for establishing the radio link. The radio link may be based on one or more orthogonal frequency-division multiplexing (OFDM) carriers from a frequency spectrum that is shared on the basis of a contention-based mechanism, e.g. , an unlicensed or license exempt band like 2.4 GHz Industrial, Scientific, and Medical (ISM) band, the 5 GHz band, the 6 GHz band, or the 60 GHz band.

[0167] Each AP 1010 may provide data connectivity to STAs 1012 connected to a particular AP 1010. As illustrated, APs 1010 may be connected to a data network 1030. In this way, APs 1010 may also provide data connectivity between STAs 1012 and other entities, e.g., to one or more servers, service providers, data sources, data sinks, user terminals, or the like. Accordingly, the radio link established between a given STA 1012 and its serving AP 1010 may be used for providing various kinds of services to STA 1012, e.g., a voice service, a multimedia service, or other data service. Such services may be based on applications that are executed on STA 1012 and / or on a device linked to STA 1012. By way of example, Figure 10 illustrates an application service platform 1032 provided in data network 1030. The application(s) executed on STA 1012 and / or on one or more other devices linked to STA 1012 may use the radio link for data communication with one or more other STA 1012 and / or the application service platform 1032, thereby enabling utilization of the corresponding service(s) at STA 1012.

[0168] Figure 11 shows a wireless device 1100, which may be configured to operate in communication system 900 of Figure 9 or in communication system 1000 of Figure 10. The wireless device 1100 may be alternatively referred to as a UE 1100, like a UE 912 within the context of communication system 900, or as a station (STA) 1100 or as a non-access-point station (non-AP STA) 1100, like a STA 1012 within the context of the communication system 1000, in accordance with respective embodiments. As used herein, a wireless device refers to a device capable, configured, arranged and / or operable to communicate wirelessly with network nodes and / or other wireless devices. Examples of a wireless device include, but are not limited to, a smart phone, mobile phone, cell phone, voice over IP (VoIP) phone, wireless local loop phone, desktop computer, personal digital assistant (PDA), wireless cameras, gaming console or device, music storage device, playback appliance, wearable terminal device, wireless endpoint, mobile station, tablet, laptop, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), smart device, wireless customer-premise equipment (CPE), vehicle, vehicle-mounted or vehicle embedded / integrated wireless device, and wireless terminal. Other examples include any type of UE identified by the 3rd Generation Partnership Project (3GPP), including a narrow band internet of things (NB-IoT) UE, a machine type communication (MTC) UE, and / or an enhanced MTC (eMTC) UE.

[0169] A wireless device 1100 may support device-to-device (D2D) communication, for example by implementing a 3GPP standard for sidelink communication, Dedicated Short-Range Communication (DSRC), vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), or vehicle-to- everything (V2X). In other examples, wireless device 1100 may not necessarily have a user in the sense of a human user who owns and / or operates the relevant device. Instead, wireless device 1100 may represent a device that is intended for sale to, or operation by, a human user but which may not, or which may not initially, be associated with a specific human user (e.g., a smart sprinkler controller). Alternatively, wireless device 1100 may represent a device that is not intended for sale to, or operation by, an end user but which may be associated with or operated for the benefit of a user (e.g., a smart power meter).

[0170] In particular embodiments, wireless device 1100 includes processing circuitry 1102 that is operatively coupled via a bus 1104 to an input / output interface 1106, a power source 1108, a memory 1110, a communication interface 1112, and / or any other component, or any combination thereof. Certain embodiments of wireless device 1100 may include all or a subset of the components shown in Figure 11. The level of integration between the components may vary from one embodiment of wireless device 1100 to another. In general, in a particular embodiment of wireless device 1100, processing circuitry 1102, input / output interface 1106, power source 1108, memory 1110, and communication interface 1112 may, in whole or in part, represent or include physical components common to or shared by one or more of the other elements of wireless device 1100. Further, certain embodiments of wireless devices 1100 may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.

[0171] The processing circuitry 1102 is configured to process instructions and data and may be configured to implement any sequential state machine operative to execute instructions stored as machine-readable computer programs in the memory 1110. The processing circuitry 1102 may be implemented as one or more hardware-implemented state machines (e.g., in discrete logic, field- programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), etc.); programmable logic together with appropriate firmware; one or more stored computer programs, general-purpose processors, such as a microprocessor or digital signal processor (DSP), together with appropriate software; or any combination of the above. For example, the processing circuitry 1102 may include multiple central processing units (CPUs). In the example, the input / output interface 1106 may be configured to provide an interface or interfaces to an input device, output device, or one or more input and / or output devices. Examples of an output device include a speaker, a sound card, a video card, a display, a monitor, a printer, an actuator, an emitter, a smartcard, another output device, or any combination thereof. An input device may allow a user to capture information into wireless device 1100. Examples of an input device include a touch-sensitive or presence-sensitive display, a camera (e.g., a digital camera, a digital video camera, a web camera, etc.), a microphone, a sensor, a mouse, a trackball, a directional pad, a trackpad, a scroll wheel, a smartcard, and the like. The presence-sensitive display may include a capacitive or resistive touch sensor to sense input from a user. A sensor may be, for instance, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, a biometric sensor, etc., or any combination thereof. An output device may use the same type of interface port as an input device. For example, a Universal Serial Bus (USB) port may be used to provide an input device and an output device.

[0172] In some embodiments, the power source 1108 is structured as a battery or battery pack. Other types of power sources, such as an external power source (e.g., an electricity outlet), photovoltaic device, or power cell, may be used to supply power to circuitry or to charge an associated battery. The power source 1108 may further include power circuitry for delivering power from the power source 1108 itself, and / or an external power source, to the various parts of wireless device 1100 via input circuitry or an interface such as an electrical power cable. Power source 1108 may perform any formatting, converting, or other modification to make accessible power suitable for the respective components of the wireless device 1100 to which power is supplied.

[0173] The memory 1110 may be or be configured to include memory such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth. In one example, the memory 1110 includes one or more programs 1114, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data 1116. The memory 1110 may store, for use by wireless device 1100, any of a variety of various operating systems or combinations of operating systems.

[0174] The memory 1110 may be configured to include a number of physical drive units, such as redundant array of independent disks (RAID), flash memory, USB flash drive, external hard disk drive, thumb drive, pen drive, key drive, high-density digital versatile disc (HD-DVD) optical disc drive, internal hard disk drive, Blu-Ray optical disc drive, holographic digital data storage (HDDS) optical disc drive, external mini-dual in-line memory module (DIMM), synchronous dynamic random access memory (SDRAM), external micro-DIMM SDRAM, smartcard memory such as tamper resistant module in the form of a universal integrated circuit card (UICC) including one or more subscriber identity modules (SIMs), such as a USIM and / or ISIM, other memory, or any combination thereof. The UICC may for example be an embedded UICC (eUICC), integrated UICC (iUICC) or a removable UICC commonly known as ‘SIM card.’ The memory 1110 may allow wireless device 1100 to access instructions, programs and the like, stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system may be tangibly embodied as or in the memory 1110, which may be or comprise a device-readable storage medium.

[0175] The processing circuitry 1102 may be configured to communicate with an access network or other network via or using the communication interface 1112. The communication interface 1112 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 1122. The communication interface 1112 may include one or more transceivers used to communicate, such as by communicating with one or more remote transceivers of another device capable of wireless communication (e.g., another wireless device or a network node in an access network). Each transceiver may include a transmitter 1118 and / or a receiver 1120 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter 1118 and receiver 1120 may be coupled to one or more antennas (e.g., antenna 1122) and may share circuit components, software or firmware, or alternatively be implemented separately.

[0176] In the illustrated embodiment, communication functions of the communication interface 1112 may include cellular communication, Wi-Fi communication (e.g., according to an IEEE 802.11 family standard), LPWAN communication, data communication, voice communication, multimedia communication, short-range communications such as Bluetooth, near-field communication, location-based communication such as the use of the global positioning system (GPS) to determine a location, another like communication function, or any combination thereof. Communications may be implemented according to one or more communication protocols and / or standards, such as IEEE 802.11, Code Division Multiplexing Access (CDMA), Wideband Code Division Multiple Access (WCDMA), GSM, LTE, New Radio (NR), UMTS, WiMax, Ethernet, transmission control protocol / intemet protocol (TCP / IP), synchronous optical networking (SONET), Asynchronous Transfer Mode (ATM), QUIC, Hypertext Transfer Protocol (HTTP), and so forth.

[0177] In particular embodiments, wireless device 1100 may provide an output of data captured via a sensor, through its communication interface 1112, via a wireless connection to a network node, and / or in any appropriate manner. Data captured by sensors of a wireless device 1100 can be communicated through a wireless connection to a network node via another wireless device 1100. In particular embodiments, such output may be periodic (e.g., once every 15 minutes if it reports the sensed temperature), random (e.g., to even out the load from reporting from several sensors), in response to a triggering event (e.g., when moisture is detected an alert is sent), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient).

[0178] As another example, wireless device 1100 comprises an actuator, a motor, or a switch, related to a communication interface configured to receive wireless input from a network node via a wireless connection. In response to the received wireless input the states of the actuator, the motor, or the switch may change. For example, wireless device 1100 may comprise a motor that adjusts the control surfaces or rotors of a drone in flight according to the received input or to a robotic arm performing a medical procedure according to the received input.

[0179] Wireless device 1100, when in the form of an Internet of Things (loT) device, may be a device for use in one or more application domains, these domains comprising, but not limited to, wearable technology, extended industrial application and healthcare. Non-limiting examples of such an loT device are a device which is or which is embedded in: a connected refrigerator or freezer, a TV, a connected lighting device, an electricity meter, a robot vacuum cleaner, a voice controlled smart speaker, a home security camera, a motion detector, a thermostat, a smoke detector, a door / window sensor, a flood / moisture sensor, an electrical door lock, a connected doorbell, an air conditioning system like a heat pump, an autonomous vehicle, a surveillance system, a weather monitoring device, a vehicle parking monitoring device, an electric vehicle charging station, a smart watch, a fitness tracker, a wearable for tactile augmentation or sensory enhancement, a water sprinkler, an animal- or item-tracking device, a sensor for monitoring a plant or animal, an industrial robot, an Unmanned Aerial Vehicle (UAV), and any kind of medical device, like a heart rate monitor or a remote controlled surgical robot. In particular embodiments, wireless device 1100 represents an loT device that comprises circuitry and / or software in dependence of the intended application of the loT device in addition to other components as described in relation to the example embodiment of wireless device 1100 shown in Figure 11.

[0180] As yet another specific example, in an loT scenario, wireless device 1100 may represent a machine or other device that performs monitoring and / or measurements, and transmits the results of such monitoring and / or measurements to another wireless device and / or a network node. Wireless device 1100 may in this case be an M2M device, which may in a 3GPP context be referred to as an MTC device. As one particular example, wireless device 1100 may implement the 3GPP NB-IoT standard. In other scenarios, wireless device 1100 may represent a vehicle, such as a car, a bus, a truck, a ship and an airplane, or other equipment that is capable of monitoring and / or reporting on its operational status or other functions associated with its operation.

[0181] In practice, any number of wireless devices 1100 may be used together with respect to a single use case. For example, a first wireless device 1100 might be or be integrated in a drone and provide the drone’s speed information (obtained through a speed sensor) to a second wireless device 1100 that is a remote controller operating the drone. When a user makes changes from the remote controller, the first wireless device 1100 may adjust the throttle on the drone (e.g. by controlling an actuator) to increase or decrease the drone’s speed. The first and / or the second wireless device 1100 can also include more than one of the functionalities described above. For example, wireless device 1100 might comprise the sensor and the actuator, and handle communication of data for both the speed sensor and the actuators.

[0182] Figure 12 shows a network node 1200 in accordance with some embodiments. As used herein, network node refers to equipment capable, configured, arranged and / or operable to communicate directly or indirectly with a UE and / or with other network nodes or equipment, in a telecommunications network. In accordance with respective embodiments, network node 1200 may be configured to operate in communication system 900 of Figure 9, like network nodes 908 or 910, or in communication system 1000 of Figure 10, like an AP 1010 or a station 1012. Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (BSs) (e.g., radio base stations, Node Bs, evolved Node Bs (eNBs) and NR NodeBs (gNBs)), O-RAN nodes or components of an O-RAN node (e.g., O-RU, O-DU, O-CU).

[0183] Network nodes 1200 may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. Network node 1200 may be a relay node or a relay donor node controlling a relay. Network nodes 1200 may also include one or more (or all) parts of a distributed radio base station such as centralized digital units, distributed units (e.g., in an O-RAN access node) and / or remote radio units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remote radio units may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS).

[0184] Other examples of network nodes 1200 include multiple transmission point (multi-TRP) 5G access nodes, multi-standard radio (MSR) equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, multi-cell / multicast coordination entities (MCEs), Operation and Maintenance (O&M) nodes, Operations Support System (OSS) nodes, Self-Organizing Network (SON) nodes, positioning nodes (e.g., Evolved Serving Mobile Location Centers (E-SMLCs)), and / or Minimization of Drive Tests (MDTs).

[0185] In particular embodiments, network node 1200 includes a processing circuitry 1202, a memory 1204, a communication interface 1206, and a power source 1208. In general, in a particular embodiment of network node 1200, processing circuitry 1202, memory 1204, communication interface 1206, and power source 1208 may, in whole or in part, represent or include physical components common to or shared by one or more of the other elements of network node 1200.

[0186] The network node 1200 may be composed of multiple distinct network entities (e.g., a NodeB entity and a RNC entity, or a BTS entity and a BSC entity, etc.), which may each have or utilize their own respective physical components. In certain scenarios in which the network node 1200 comprises multiple such entities (e.g., BTS and BSC), one or more of the separate entities may be shared among several network nodes. For example, a single RNC may control multiple NodeBs. In such a scenario, each unique NodeB and RNC pair, may in some instances be considered a single separate network node. In some embodiments, the network node 1200 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memories 1204 or portions of memory 1204 for different RATs) and some components may be reused (e.g., a same antenna 1210 may be shared by different RATs). The network node 1200 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 1200, for example GSM, WCDMA, LTE, NR, Wi-Fi (e.g., according to an IEEE 802.11 family standard), Zigbee, Z-wave, LoRaWAN, Radio Frequency Identification (RFID) or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within network node 1200.

[0187] The processing circuitry 1202 may comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and / or encoded logic operable to provide, either alone or in conjunction with other components, such as the memory 1204, to provide network node 1200 functionality.

[0188] In some embodiments, the processing circuitry 1202 includes a system on a chip (SOC). In some embodiments, the processing circuitry 1202 includes one or more of radio frequency (RF) transceiver circuitry 1212 and baseband processing circuitry 1214. In some embodiments, the RF transceiver circuitry 1212 and the baseband processing circuitry 1214 may be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. In alternative embodiments, part or all of RF transceiver circuitry 1212 and baseband processing circuitry 1214 may be on the same chip or set of chips, boards, or units.

[0189] The memory 1204 may comprise any form of volatile or non-volatile computer-readable memory including, without limitation, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD) or a Digital Video Disk (DVD)), and / or any other volatile or non-volatile, non-transitory device-readable and / or computer-executable memory devices that store information, data, and / or instructions that may be used by the processing circuitry 1202. The memory 1204 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and / or other instructions capable of being executed by the processing circuitry 1202 and utilized by the network node 1200. The memory 1204 may be used to store any calculations made by the processing circuitry 1202 and / or any data received via the communication interface 1206. In some embodiments, the processing circuitry 1202 and memory 1204 is integrated.

[0190] The communication interface 1206 is used in wired or wireless communication of signaling and / or data with UEs, other network nodes, and / or any other network equipment. In the illustrated embodiment, communication interface 1206 comprises port(s) / terminal(s) 1216 to send and receive data, for example to and from a network over a wired connection. In particular embodiments, network node 1100 may be capable of wireless communication and communication interface 1206 may also include radio front-end circuitry 1218 that may be coupled to, or in certain embodiments a part of, an antenna 1210. Particular embodiments of radio front-end circuitry 1218 include filter(s) 1220 and amplifier(s) 1222. The radio front-end circuitry 1218 may be connected to an antenna 1210 and processing circuitry 1202. The radio front-end circuitry may be configured to condition signals communicated between antenna 1210 and processing circuitry 1202. The radio front-end circuitry 1218 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. The radio front-end circuitry 1218 may convert the digital data into a radio signal(s) having the appropriate channel and bandwidth parameters using a combination of filters 1220 and / or amplifiers 1222. The radio signal(s) may then be transmitted via the antenna 1210. Similarly, when receiving data, the antenna 1210 may collect radio signals which are then converted into digital data by the radio front-end circuitry 1218. The digital data may be passed to the processing circuitry 1202. In other embodiments, the communication interface may comprise different components and / or different combinations of components.

[0191] In certain alternative embodiments, network node 1200 may be capable of wireless communication but does not include separate radio front-end circuitry 1218, instead, the processing circuitry 1202 includes radio front-end circuitry and is connected to the antenna 1210. Similarly, in some embodiments, all or some of the RF transceiver circuitry 1212 is part of the communication interface 1206. In still other embodiments, the communication interface 1206 includes one or more ports or terminals 1216, the radio front-end circuitry 1218, and the RF transceiver circuitry 1212, as part of a radio unit (not shown), and the communication interface 1206 communicates with the baseband processing circuitry 1214, which is part of a digital unit (not shown).

[0192] The antenna 1210 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. The antenna 1210 may be coupled to the radio front-end circuitry 1218 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna 1210 is separate from the network node 1200 and connectable to the network node 1200 through one or more interfaces or ports.

[0193] The antenna 1210, communication interface 1206, and / or the processing circuitry 1202 may be configured to perform some or all of the receiving operations and / or obtaining operations described herein as being performed by the network node 1200. Any information, data and / or signals may be received from a UE, another network node and / or any other network equipment. Similarly, the antenna 1210, the communication interface 1206, and / or the processing circuitry 1202 may be configured to perform some or all of the transmitting or sending operations described herein as being performed by the network node 1200. Any information, data and / or signals may be transmitted to a UE, another network node and / or any other network equipment.

[0194] The power source 1208 provides power to the various components of network node 1200 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source 1208 may further comprise, or be coupled to, power management circuitry to supply the components of the network node 1200 with power for performing the functionality described herein. For example, the network node 1200 may be connectable to an external power source (e.g., the power grid, an electricity outlet) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source 1208. As a further example, the power source 1208 may comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry. The battery may provide backup power should the external power source fail.

[0195] Embodiments of the network node 1200 may include additional components beyond those shown in Figure 12 for providing certain aspects of the network node’s functionality, including any of the functionality described herein and / or any functionality necessary to support the subject matter described herein. For example, the network node 1200 may include user interface equipment to allow input of information into the network node 1200 and to allow output of information from the network node 1200. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node 1200.

[0196] Figure 13 is a block diagram illustrating a virtualization environment 1300 in which functions implemented by some embodiments may be virtualized. In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices and networking resources. As used herein, virtualization can be applied to any device described herein, or components thereof, and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines (VMs) implemented in one or more virtual environments 1300 hosted by one or more of hardware nodes, such as a hardware computing device that operates as an access network node, UE, core network node, or host. Further, in embodiments in which a virtual node does not require radio connectivity (e.g., a core network node or host), then the node may be entirely virtualized. In some embodiments, the virtualization environment 1300 includes components defined by the O-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an O-2 interface.

[0197] Applications 1302 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment Q400 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein.

[0198] Hardware 1304 includes processing circuitry, memory that stores software and / or instructions executable by hardware processing circuitry, and / or other hardware devices as described herein, such as a network interface, input / output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers 1306 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VM 1308A and VM 1308B (which may be collectively referred to as VMs 1308), and / or perform any of the functions, features and / or benefits described in relation with some embodiments described herein. The virtualization layer 1306 may present a virtual operating platform that appears like networking hardware to one or more of the VMs 1308.

[0199] The VMs 1308 comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by virtualization layer 1306. Different embodiments of the instance of a virtual appliance 1302 may be implemented on one or more of VMs 1308, and the implementations may be made in different ways. Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment.

[0200] In the context of NFV, each of the VMs 1308 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each of the VMs 1308, and that part of hardware 1304 that executes that VM, be it hardware dedicated to that VM and / or hardware shared by that VM with others of the VMs, forms separate virtual network elements. Still in the context of NFV, a virtual network function is responsible for handling specific network functions that run in one or more of the VMs 1308 on top of the hardware 1304 and corresponds to an application 1302.

[0201] Hardware 1304 may be implemented in a standalone network node with generic or specific components. Hardware 1304 may implement some functions via virtualization. Alternatively, hardware 1304 may be part of a larger cluster of hardware (e.g. such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration 1310, which, among others, oversees lifecycle management of applications 1302. In some embodiments, hardware 1304 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. In some embodiments, some signaling can be provided with the use of a control system 1312 which may alternatively be used for communication between hardware nodes and radio units.

[0202] Although the computing devices described herein (e.g., UEs, network nodes, hosts) may include the illustrated combination of hardware components, other embodiments may comprise computing devices with different combinations of components. It is to be understood that these computing devices may comprise any suitable combination of hardware and / or software needed to perform the tasks, features, functions and methods disclosed herein. Determining, calculating, obtaining or similar operations described herein may be performed by processing circuitry, which may process information by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored in the network node, and / or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination. Moreover, while components are depicted as single boxes located within a larger box, or nested within multiple boxes, in practice, computing devices may comprise multiple different physical components that make up a single illustrated component, and functionality may be partitioned between separate components. For example, a communication interface may be configured to include any of the components described herein, and / or the functionality of the components may be partitioned between the processing circuitry and the communication interface. In another example, non-computationally intensive functions of any of such components may be implemented in software or firmware and computationally intensive functions may be implemented in hardware.

[0203] In certain embodiments, some or all of the functionality described herein may be provided by processing circuitry executing instructions stored on in memory, which in certain embodiments may be a computer program product in the form of a non-transitory computer-readable storage medium. In alternative embodiments, some or all of the functionality may be provided by the processing circuitry without executing instructions stored on a separate or discrete device-readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a non-transitory computer-readable storage medium or not, the processing circuitry can be configured to perform the described functionality. The benefits provided by such functionality are not limited to the processing circuitry alone or to other components of the computing device, but are enjoyed by the computing device as a whole, and / or by end users and a wireless network generally.

[0204] The disclosed embodiments should not be seen as mutually exclusive, but feature(s) of one embodiment may be combined with feature(s) of another whenever appropriate, e.g. a field disclosed in one embodiment may be added to the fields of another embodiment and the like. It is also foreseen that it may not always be necessary to include all of the disclosed fields. Other binary value representations than those disclosed here may be used.

[0205] The methods and devices disclosed herein may be performed in RUs and DUs that are not necessarily as defined by O-RAN, for example any DU and / or RU according to 3 GPP specifications.

[0206] Messages described herein may be sent from an O-RAN O-DU to an O-RAN O-RU.

[0207] An O-RAN O-DU may be adapted to send messages described herein.

[0208] An O-RAN O-RU may be adapted to receive messages described herein, or adapted to receive and process messages described herein.

[0209] Messages described herein may be sent from any DU to any RU according to 3 GPP specifications, the DU and / or RU may be adapted similarly as above.. NUMBERED EMBODIMENTS

[0210] 1. A message for describing a sounding reference signal, SRS, configuration for a plurality of User Equipments, UEs.

[0211] 2. A message according to any preceding embodiment, the message describing the allocation of air interface resources to a plurality of UEs for sending SRS, and / or parameters required for SRS channel estimation.

[0212] 3. A message according to any preceding embodiment wherein the allocation is applicable to a slot.

[0213] 4. A message according to any preceding embodiment wherein the message is included in an O- RAN C-plane section description transmitted from an O-RAN O-DU to an O-RAN O-RU.

[0214] 5. A message according to any preceding embodiment, the message indicating one or more clusters, a cluster being a contiguous range of physical resource blocks, PRBs, in the frequency dimension.

[0215] 6. A message according to embodiment 5 wherein the message indicates for each of one or more cluster, the cluster’s location and size in the frequency dimension.

[0216] 7. A message according to embodiment 6, the location and size being indicated as either a start position and a size, an end position and a size, or a start position and an end position, all in frequency dimension.

[0217] 8. A message according to any of embodiments 5-7 wherein the PRB range of the cluster is to be used for sending SRS from one or more UEs.

[0218] 9. A message according to any preceding embodiment wherein the message indicates one or more symbols for sending SRS, the symbols being Orthogonal Frequency Division Multiplex, OFDM, symbols. 10. A message according to embodiment 9 wherein the message indicates how many symbols that are indicated in the message.

[0219] 11. A message according to any preceding embodiment and according to embodiment 5 wherein the message indicates how many clusters that are indicated in the message.

[0220] 12. A message according to any preceding embodiment and according to embodiment 9, the message comprising for each indicated symbol a symbol part.

[0221] 13. A message according to embodiment 12 wherein the symbol part comprises an indication of an identity of the symbol

[0222] 14. A message according to any of the embodiments 12-13 wherein the symbol part comprises an indication of a how many UEs that are to transmit SRS in the symbol.

[0223] 15. A message according to any of embodiments 12-14 wherein the symbol part comprises an indication of a comb number for the symbol.

[0224] 16. A message according to any of embodiments 12-15 wherein the symbol part comprises indications of SRS allocation for the symbol.

[0225] 17. A message according to embodiment 16 wherein the symbol part does not comprise any indication of SRS allocation for any other symbol.

[0226] YY1. A message according to any of the embodiments 12-17 wherein each symbol part is contained in a separate section.

[0227] YY2. A message according to embodiment YY1 wherein parameters applicable to all the symbols are contained in a section type header applicable to the sections where the symbol parts are contained.

[0228] AA1. A message according to any of the embodiments YY1 or YY2 wherein the message comprises, for one or more sections, a first section extension part, a first section extension part comprising one or more second parts wherein each second part comprises an indication of which third part of the message or section the second part of the section extension applies to. AA2. A message according to embodiment AA1 wherein each second part comprises a type identifier that identifies which kinds of third parts the second part applies to, such as cluster, UE or UE port, and further comprises one or more indications of which individual third parts of the kinds the second part applies to.

[0229] AA3. A message according to embodiment AA2 but where a type identifier of a second part indicates that the second part applies to the symbol part of the section and there is no further indication of individual parts.

[0230] 18. A message according to any of the embodiments 12-17, YY1, YY2, AA1, AA2 and AA3, and according to embodiment 5, wherein each symbol part comprises for each cluster a cluster part.

[0231] 19. A message according to embodiment 18 wherein the cluster part comprises an indication of an identity of the cluster.

[0232] 20. A message according to any of the embodiments 18-19 wherein the cluster part comprises an indication of the type of SRS symbol hopping used for the SRS within the cluster and the symbol.

[0233] 21. A message according to any of the embodiments 18-20 wherein the cluster part comprises indications of SRS allocation within the cluster and the symbol.

[0234] 22. A message according to embodiment 21 wherein the cluster part does not comprise any indication of SRS allocation for any other cluster.

[0235] 23. A message according to any of the embodiments 18-22 wherein each cluster part comprises for each UE a UE part or according to any of the embodiments 12a- 17a wherein each symbol part comprises for each UE a UE part.

[0236] 24. A message according to embodiment 23 wherein the UE part comprises an indication for a UE of one or more of the following:

[0237] - A number of SRS ports used by the UE

[0238] - An identification value indicating a capability of the UE,

[0239] - A UE identity value,

[0240] - If the UE corresponding to the UE identity value has changed or not. - An SRS sequence identity value used by the UE to generate an SRS sequence.

[0241] 25. A message according to any of the embodiments 23-24 wherein the UE part comprises an indication of SRS allocation for the UE for the symbol and the cluster.

[0242] 26. A message according to embodiment 25 wherein the UE part does not comprise any indication of SRS allocation for any other UE.

[0243] 27. A message according to any of the embodiments 23-26 wherein each UE part comprises for each UE SRS port an SRS port part.

[0244] 28. A message according to embodiment 27 wherein the SRS port part comprises indications of one or more of the following:

[0245] - A cyclic shift,

[0246] - A comb offset,

[0247] - A UE antenna port identity.

[0248] 28a. A message according to any of the embodiments 27 and 28 wherein the SRS port part comprises an indication of a cyclic shift of one or more other SRS ports than the SRS port of the SRS port part or of an offset between cyclic shifts of one or more other SRS ports than the SRS port of the SRS port part or of a cyclic shift offset to be used for channel estimation or a number of used cyclic shifts.

[0249] 28b. A message according to embodiment 28a wherein the one or more other SRS ports are ports using the same comb offset as the SRS port of the SRS port part.

[0250] 28c. A message according to any of embodiments 28a or 28b wherein the one or more other SRS ports are ports using the same cluster as the SRS port of the SRS port part.

[0251] 28d. A message according to any of the embodiments 28a-c wherein the one or more other SRS ports are ports using one or more same time-frequency resource elements as the SRS port of the SRS port part 28e. A message according to any of the embodiments 28a-d wherein the indication indicates an offset from the cyclic shift used by the SRS port of the SRS port part to the next cyclic shift used in a cyclic shift sequence used for the comb offset used by the SRS port of the SRS port part.

[0252] 28f. A message according to any of the embodiments 28a-d wherein the indication indicates an offset from the cyclic shift used by the SRS port of the SRS port part to the nearest cyclic shift used in a cyclic shift sequence used for the comb offset used by the SRS port of the SRS port part.

[0253] 28g. A message according to any of the embodiments 28a-d wherein the indication indicates offsets from the cyclic shift used by the SRS port of the SRS port part to the next cyclic shift and to the previous cyclic shift used in a cyclic shift sequence used for the comb offset used by the SRS port of the SRS port part.

[0254] 28h. A message according to any of the embodiments 28a-d wherein the indication indicates a minimum of the offsets between any cyclic shifts used in a cyclic shift sequence used for the comb offset used by the SRS port of the SRS port part.

[0255] 28i. A message according to any of the embodiments 28a-d wherein the indication indicates a cyclic shift offset to be used for channel estimation for the SRS port of the SRS port part.

[0256] 28j. A message according to any of the embodiments 28a-d wherein the indication indicates a number of cyclic shifts used for the comb offset used by the SRS port of the SRS port part

[0257] 29. A message according to embodiment 28 wherein the SRS port part does not contain any indication of SRS allocation for any other SRS port.

[0258] XXI . A message according to any of the embodiments 1-17, 18-29 wherein the message comprises a section having a section extension, the section extension comprising one or more second parts, each part comprising an indication of which third part of the message or section the part of the section extension applies to. XX2. A message according to embodiment XXI wherein each second part comprises a type identifier that identifies which kinds of third parts the second part applies to, such as symbol, cluster, UE, UE port, and further comprises one or more indications of which individual third parts of the kinds the second part applies to.

[0259] XX3. A message according to embodiment XX2 but where a type identifier of a second part indicates that the second part applies to the whole section and there is no further indication of individual parts.

[0260] WW1. A message according to any of the embodiments 1-11, the message having a section part for each of one or more SRS blocks.

[0261] WW2. A message according to embodiment WW1 wherein for each of one or more SRS blocks there is in the message for each of one or more used SRS comb offset an indication of a minimum of the distances between any two cyclic shifts used for the comb offset.

[0262] WW3. A message according to embodiment WW1 wherein for each of one or more SRS blocks there is in the message for each of one or more used SRS comb offset an indication of the number of cyclic shifts used for the comb offset.

[0263] WW4. A message according to embodiment WW1 wherein for each of one or more SRS blocks there is in the message for each of one or more used SRS comb offset an indication of a cyclic shift offset to be used for channel estimation.

[0264] WW23. A message according to embodiment WW1 wherein each SRS block section part comprises for each UE a UE part.

[0265] WW24. A message according to embodiment WW23 wherein the UE part comprises an indication for a UE of one or more of the following: - A number of SRS ports used by the UE

[0266] - An identification value indicating a capability of the UE,

[0267] - A UE identity value,

[0268] - If the UE corresponding to the UE identity value has changed or not.

[0269] - An SRS sequence identity value used by the UE to generate an SRS sequence.

[0270] WW25. A message according to any of the embodiments WW23-WW24 wherein the UE part comprises an indication of SRS allocation for the UE for the symbol and the cluster.

[0271] WW26. A message according to embodiment WW25 wherein the UE part does not comprise any indication of SRS allocation for any other UE.

[0272] WW27. A message according to any of the embodiments WW23-WW26 wherein each UE part comprises for each UE SRS port an SRS port part.

[0273] WW28. A message according to embodiment WW27 wherein the SRS port part comprises indications of one or more of the following:

[0274] - A cyclic shift,

[0275] - A comb offset,

[0276] - A UE antenna port identity.

[0277] WW29. A message according to embodiment WW28 wherein the SRS port part does not contain any indication of SRS allocation for any other SRS port.

[0278] BB1. A message according to embodiment WW1, the message comprising, for one or more sections a first section extension part, the first section extension part comprising one or more second parts wherein each such second part comprises an indication of which third part of the message or section the second part of the section extension applies to.

[0279] BB2. A message according to embodiment BB1 wherein each second part comprises a type identifier that identifies which kinds of third parts the second part applies to, such as UE, UE port, and further comprises one or more indications of which individual third parts of the kinds the second part applies to. BB3. A message according to embodiment BB2 but where a type identifier of a second part indicates that the second part applies to the whole section and there is no further indication of individual parts.

[0280] 30. A message according to any of the embodiments 23-29 or WW23-WW29 wherein the message comprises an indication that information indicated for a UE or a UE SRS port for a symbol and a cluster is to be applied to the UE or UE SRS port also for other symbols or clusters.

[0281] 30x. A message according to any preceding embodiment when dependent on embodiment 3, the message comprising an indication that a subsequent message will comprise further information applicable to the slot.

[0282] 30a. A message according to embodiment 50 or any embodiment subsequent to 50.

[0283] 31. A message according to any combination of any of the preceding embodiments.

[0284] 32. A method performed in a first network node comprising transmitting a message according to any of the embodiments 1-31, YY1-YY2, AA1-AA3, XX1-XX3, WW1, WW23-29 or BB1-BB3 or any of the preceding message embodiments to a second network node wherein the message is for use for SRS reception and processing by the second network node.

[0285] 33. A method performed in a second network node comprising receiving a message according to any of the embodiments 1-31, YY1-YY2, AA1-AA3, XX1-XX3, WW1, WW23-29 or BB1-BB3 or any of the preceding message embodiments from a first network node and performing SRS reception and processing based on the SRS allocation described in the message.

[0286] 34. A method according to any of the embodiments 32-33 wherein SRS processing comprises channel estimation.

[0287] 35. A method according to any of the embodiments embodiment 32-34 wherein the first network node is an O-RAN O-DU and the second network node is an O-RAN O-RU. 36. A network node configured to perform the method of any of the embodiments 32-35 as the first or the second network node.

[0288] 37. A first network node configured to perform the method of embodiment 32 or embodiment 34 when dependent on embodiment 32 wherein the first network node is an O-RAN O-DU.

[0289] 38. A second network node configured to perform the method of embodiment 33 or embodiment 34 when dependent on embodiment 33 wherein the second network nod is an O-RAN O-RU.

[0290] 39. A network node for transmitting or receiving an SRS configuration, the network node comprising: processing circuitry configured to perform the method of any of the embodiments 32-35; and a power source circuitry configured to supply power to the processing circuitry.

[0291] 40. A computer program comprising program code which when run on a network node causes the network node to perform the method of any of the embodiments 32-35.

[0292] 41. A computer program product comprising a computer program according to embodiment 40 and a computer readable means on which the computer program is stored.

[0293] 42. A network node comprising a processor and memory, said memory containing instructions executable by said processing circuitry whereby the network node is operative for performing the method of any of the embodiments 32-35.

[0294] 50. A message according to any of embodiments 24 or WW24 or any embodiment dependent on those embodiments wherein the identification value indicating a capability of the UE, ueCapId, indicates a total number of physical antennas of the UE that can be used for communicating signals.

[0295] 51. A message according to any of embodiments 24 or WW24 or any embodiment dependent on those embodiments wherein the identification value indicating a capability of the UE, ueCapId, indicates a number of UE antennas that can be used simultaneously for transmission of uplink signals.

[0296] 52. A message according to any of embodiments 24 or WW24 or any embodiment dependent on those embodiments wherein the identification value indicating a capability of the UE, ueCapId, indicates a number of UE antennas that can be used simultaneously for transmission of SRS signals.

[0297] 53. A message according to any of embodiments 24 or WW24 or any embodiment dependent on those embodiments wherein the identification value indicating a capability of the UE, ueCapId, indicates a number of transmitters of the UE for transmitting signals.

[0298] 53x. A message according to any of embodiments 24 or WW24 or any embodiment dependent on those embodiments wherein the identification value indicating a capability of the UE, ueCapId, indicates a number of UE antennas that can be used simultaneously for reception of signals.

[0299] 54. A message according to any of embodiments 24 or WW24 or any embodiment dependent on those embodiments wherein the identification value indicating a capability of the UE, ueCapId, indicates a number of UE antennas that can be used simultaneously for reception of signals.

[0300] 55. A message according to any of embodiments 24 or WW24 or any embodiment dependent on those embodiments wherein the identification value indicating a capability of the UE, ueCapId, is an index which identifies a particular combination of a number of antennas simultaneously usable for transmission of SRS signals and a number of receivers simultaneously usable for reception of signals.

[0301] 56. A message according to any of embodiments 24 or WW24 or any embodiment dependent on those embodiments wherein the identification value indicating a capability of the UE, ueCapId, indicates a number of UE antennas that can be used simultaneously for reception of signals but not a number of UE antennas that can be used for simultaneous transmission.

[0302] 57. A message according to embodiment 56 wherein the message comprises an indication of a number of UE antennas that can be used for simultaneous transmission but the indication is not part of the ueCapId.

[0303] Section type, section and section extension refer to the terminology of the O-RAN standard for communication over the fronthaul interface between O-DU and O-RU. The signals referred to in embodiments 50-57 may be signals according to 3GPP standards. They may be for communication between a UE and an O-RAN O-RU, or generally between a UE and a 3GPP gNB / eNB.

[0304] Typically all the antennas of a UE for receiving or transmitting 3GPP signals can be used for transmission and / or reception. But often, the number of transmitters is less than the number of antennas and then all antennas typically can be used for transmission, but not simultaneously. Normally xTyR (e.g. 1T2R, 2T4R, etc.) corresponds to the UE having y antennas, each with a corresponding receiver and x transmitters where x is less than or equal to y.

[0305] In an alternative, the order of symbol and cluster level may e.g. be reversed.

[0306] In an alternative, instead of embodiments 18-22, embodiments 18a-22a below may be used. Instead of embodiments 12-17, embodiments 12a-17a below may be used.

[0307] 18a. A message according to any of the embodiments 1-11 and according to embodiment 5, wherein the message comprises for each indicated cluster a cluster part.

[0308] 19a. A message according to embodiment 18a wherein the cluster part comprises an indication of an identity of the cluster.

[0309] 20a. Deleted

[0310] 21a. A message according to any of the embodiments 18a-20a wherein the cluster part comprises indications of SRS allocation within the cluster.

[0311] 22a. A message according to embodiment 21a wherein the cluster part does not comprise any indication of SRS allocation for any other cluster.

[0312] 12a. A message according to any of the embodiments 18a-22a and according to embodiment 9, wherein each cluster part comprises for each cluster a symbol part.

[0313] 13a. A message according to embodiment 12a wherein the symbol part comprises an indication of an identity of the symbol. 14a. A message according to any of the embodiments 12a-13a wherein the symbol part comprises an indication of a how many UEs that are to transmit SRS in the symbol and the cluster or the symbol part comprises an indication of the type of SRS symbol hopping used for the SRS within the symbol and the cluster.

[0314] 15a. A message according to any of embodiments 12a-14a wherein the symbol part comprises an indication of a comb number for the symbol and the cluster.

[0315] 16a. A message according to any of embodiments 12a-15a wherein the symbol part comprises indications of SRS allocation for the symbol and the cluster.

[0316] 17a. A message according to embodiment 16a wherein the symbol part does not comprise any indication of SRS allocation for any other symbol.

[0317] Further disclosure: Parts of patent application PCT / SE2024 / 051026

[0318] In SRS-BF, the key is to perform SRS channel estimation in the O-RU. To enable this, the O-DU needs to provide SRS configuration information to the O-RU via C-Plane messages. After receiving the C-Plane message containing SRS configuration information, the O-RU can generate the corresponding SRS sequences and perform SRS channel estimation for each UE which sent the SRS signal.

[0319] In 3 GPP, SRS can be sent in some symbols in the special slot which contains both DL and UL transmissions or an UL slot which only contains UL transmissions. SRS can be configured as periodic, aperiodic, or semi-periodic. Each UE is informed by the base station the SRS configuration which will be used by the UE to generate its SRS. The SRS of one UE can have multiple SRS ports if it has multiple antenna ports. One antenna port may be one physical antenna or a virtual antenna by beamforming with multiple antennas. Each SRS port corresponds to the SRS sent by one UE antenna port. The SRS ports of one or more UEs are allocated with orthogonal resources in frequency domain, time domain, or code domain. In frequency domain, different ports can use different Comb Offsets, i.e., using different resource elements (REs) in the same PRBs. They can also use different PRB ranges. In time domain, they can use different symbols. In code domain, they can use different Cyclic Shifts (CS) which makes the SRS sequence orthogonal. An SRS symbol can multiplex many SRS ports. For example, with full bandwidth sounding per UE, one SRS symbol can multiplex 48 SRS ports. With half bandwidth sounding per UE, one SRS symbol can multiplex 96 SRS ports. The number of SRS ports further increases when multiple SRS symbols are used, e.g., 2, 4, 6 SRS symbols. SRS also supports various features such as frequency hopping, repetition, antenna switching etc. It is also constrained by the UE capabilities such as 1T4R, 2T4R, 1T2R, bandwidth part, etc. Considering all these above, SRS resource multiplexing can be very complicated, much more complicated than DMRS resources which only have a few ports and a few configurations.

[0320] The C-Plane SRS configuration description structure needs to be carefully designed to optimize for flexibility (supporting all possible resource multiplexing), O-RU processing efficiency (for O-RU to easily get the necessary information for generating SRS sequences) and FH efficiency (reduce the number of bytes used for SRS configuration description).

[0321] In this disclosure, we provide efficient C-Plane message structures to describe the SRS configuration of all SRS ports in a slot containing SRS in one section description, if it is within the pay load size limit of the packet. An example: First, we define a PRB cluster as a unique continuous PRB range used at least by one UE in any SRS symbol in the slot. A PRB cluster can be defines as the start PRB and the end PRB, or the start PRB and the number of PRBs. And each PRB cluster is assigned by a cluster ID. And each SRS symbol is assigned by a symbol ID in the slot. Then, each SRS resource can be identified by a cluster ID and a symbol ID. In this way, all SRS resources are mapped in a grid of cluster IDs and symbol IDs. In the C-Plane section description, we first define the PRB clusters and assign a cluster ID for each PRB cluster. Assignment of cluster ID can be explicitly done by setting the cluster ID in the section description. It can be also implicitly done by setting a rule. For example, cluster ID n-1 is assigned to the nth PRB cluster defined in the section description. After the defining the grid of cluster IDs and symbol IDs, the SRS configuration description is provided symbol by symbol. For each symbol, the SRS configuration description is provided PRB cluster by PRB cluster. For each PRB cluster in a symbol, the SRS configuration description is provided UE by UE. For each UE, the SRS configuration description is provided SRS port by SRS port. Basically, SRS configuration description contains 5 levels of description, i.e., common level, symbol level, PRB cluster level, UE level, SRS port level. Common level contains the common information for all SRS ports in all symbols and the definition of cluster ID and symbol ID grid. Symbol level contains the common information for all SRS ports in each symbol identified by a symbol ID. PRB cluster level contains the common information for all SRS ports in each PRB cluster identified by a cluster ID in each symbol. UE level contains the common information for all SRS ports of each UE identified by an SRS UE ID in each cluster in each symbol. SRS port level contains the information for each SRS port identified by an SRS port ID of each UE in each cluster in each symbol.

[0322] The SRS configuration description structure can be included a new Section Type or a new Section Extension.

[0323] If the same SRS configuration is used in different SRS resources for the SRS ports of the same UE, the repetition of the same description can be avoided by adding a field indicating the repetition of the same description without repeating the description. This can be done on UE level and / or SRS port level. This will help save some bytes in the C-Plane message.

[0324] Another possibility is to have the PRB cluster level before the symbol level. Basically, after common level, the description provides PRB cluster level description and then symbol level description. So, it starts describing PRB cluster by PRB cluster. Then, describe symbol by symbol in each PRB cluster. Afterwards, describe UE level and SRS port level.

[0325] The disclosure is applicable to any use case when SRS channel estimation is performed in the O- RU. It is applicable to not only DL implementation but also UL implementation, when SRS channel estimation is performed in the O-RU.

[0326] Certain aspects of the disclosure may provide, inter aha, one or more of the following advantages.

[0327] The SRS configuration description structure is fronthaul efficient. It is more efficient that PRB range information is coded in cluster ID, instead of using two parameters of the start PRB and the end PRB, or the start PRB and the number of PRBs. Cluster ID uses much fewer bits than using two parameters. The appearances of symbol ID and cluster ID are minimized, which only appears on symbol level and cluster level, respectively.

[0328] O-RU needs to know the configuration of all SRS ports in an SRS resource in order to perform channel estimation. The structure provides all SRS ports in a PRB cluster in a symbol together. So, O-RU can get the information efficiently after reading the description of a PRB cluster in a symbol. It doesn’t need to read further in the section description. So, it increases O-RU processing efficiency.

[0329] The structure provides the SRS configuration of all SRS ports in slot in one section description. It reduces the FH overhead with only one section description. O-RU processing is also efficient without the need to read multiple sections or messages.

[0330] Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

[0331] Example of SRS configuration description

[0332] Figure 14 (corresponding to figure 6 in PCT / SE2024 / 051026) shows an example of SRS configuration for 4 UEs. In this example, each UE has to antenna ports. Two SRS symbols are used, i.e., symbol 10 and 11, in the slot. In frequency domain multiplexing, Comb 4 is used. Each UE uses half bandwidth with frequency hopping. It also shows the two PRB clusters according to the definition in this disclosure. There are two UEs in each PRB cluster in any symbol. Two antenna ports of a UE use two Cyclic Shifts of CS 0 and CS 6.

[0333] The following provides an example of the SRS configuration description structure for the SRS configuration example shown in Figure 14, providing 5 levels information regarding SRS configuration for all UE SRS ports in a slot in an efficient and well-structured way.

[0334] • Common level SRS configuration description

[0335] -numSrsSymbols = 2 -numSrsClusters = 2 -PRB cluster definition

[0336] • Definition of PRB cluster 0

[0337] - srsClusterld = 0

[0338] - startPrbOfCluster = 0

[0339] - numPrbOfCluster = 136

[0340] • Definition of cluster 1

[0341] - srsClusterld = 1

[0342] - startPrbOfCluster = 136

[0343] - numPrbOfCluster = 136

[0344] • Symbol level SRS configuration description

[0345] -First symbol

[0346] • symbolld = 10

[0347] • numSrsUesOfSymbol = 4

[0348] • srsCombNum = 4

[0349] • PRB cluster level for first symbol

[0350] - First PRB cluster

[0351] • srsClusterld = 0

[0352] • srsGroupSeqHopping = 'groupHopping'

[0353] • UE level for first cluster in first symbol

[0354] • UE specific parameters for first UE. • SRS port level for first UE

[0355] • SRS port specific parameters for first SRS port of UE 0

[0356] • SRS port specific parameters for second SRS port of UE 0

[0357] • UE specific parameters for second UE.

[0358] • SRS port level for second UE

[0359] • SRS port specific parameters for first SRS port of UE 1

[0360] • SRS port specific parameters for second SRS port of UE 1

[0361] - Second PRB cluster

[0362] • srsClusterld = 1

[0363] • srsGroupSeqHopping = 'groupHopping'

[0364] • UE level for second cluster in first symbol

[0365] • UE specific parameters for first UE.

[0366] • SRS port level for first UE

[0367] • SRS port specific parameters for first SRS port of UE 2

[0368] • SRS port specific parameters for second SRS port of UE 2

[0369] • UE specific parameters for second UE.

[0370] • SRS port level for second UE

[0371] • SRS port specific parameters for first SRS port of UE 3

[0372] • SRS port specific parameters for second SRS port of UE 3

[0373] -Second symbol

[0374] • symbolld = 11

[0375] • numSrsUesOfSymbol = 4

[0376] • srsCombNum = 4

[0377] • PRB cluster level for second symbol

[0378] - First PRB cluster

[0379] • srsClusterld = 0

[0380] • srsGroupSeqHopping = 'groupHopping'

[0381] • UE level for first cluster in second symbol

[0382] • UE specific parameters for first UE.

[0383] • SRS port level for first UE

[0384] • SRS port specific parameters for first SRS port of UE 2

[0385] • SRS port specific parameters for second SRS port of UE2

[0386] • UE specific parameters for second UE.

[0387] • SRS port level for second UE • SRS port specific parameters for first SRS port of UE3

[0388] • SRS port specific parameters for second SRS port of UE 3

[0389] - Second PRB cluster

[0390] • srsClusterld = 1

[0391] • srsGroupSeqHopping = 'groupHopping'

[0392] • UE level for second cluster in second symbol

[0393] • UE specific parameters for first UE.

[0394] • SRS port level for first UE

[0395] • SRS port specific parameters for first SRS port of UE 0

[0396] • SRS port specific parameters for second SRS port of UE 0

[0397] • UE specific parameters for second UE.

[0398] • SRS port level for second UE

[0399] • SRS port specific parameters for first SRS port of UE 1

[0400] • SRS port specific parameters for second SRS port of UE 1

[0401] The following lists an example of UE specific parameters for any UE. This is an example, which doesn’t exclude the possibility to add other UE specific parameters.

[0402] • UE specific parameters for any UE

[0403] -numSrsPortsOfUe

[0404] -ueCapId

[0405] -srsUeldReset

[0406] -srsUeld

[0407] -srsSequenceld

[0408] The following lists an example of SRS port specific parameters for any UE. This is an example, which doesn’t exclude the possibility to add other SRS port specific parameters.

[0409] • SRS port specific parameters

[0410] -srsUePortld

[0411] -srsCyclicShift

[0412] -srsCombOffset

[0413] Example of new Section Type for SRS configuration description

[0414] In the following, we show an example of a new Section Type format (Section Type ZZ) supporting the SRS configuration description described in this disclosure, providing 5 levels information regarding SRS configuration for all UE SRS ports in a slot in an efficient and well- structured way. A similar structure can be used to define a new Section Extension for SRS configuration description. In this case, the new Section Extension can be used together with an existing Section Type or a new Section Type.

[0415] In this document, we focus on Table Cl shows the format of Section Type ZZ defined for the SRS configuration description described in this disclosure. Table C2, table C3, Table C4 and Table C5 show symbol level SRS configuration description format, PRB cluster level SRS configuration description format, UE level SRS configuration description format, and SRS port level SRS configuration description format, respectively, which are parts of Section Type ZZ.

[0416] Table Cl SRS configuration description format (Section Type ZZ) (next page)

[0417] Table C2 Symbol level SRS configuration description format

[0418] Table C3 PRB cluster level SRS configuration description format

[0419] Table C4 UE level SRS configuration description format Table C5 SRS port level SRS configuration description format

[0420] List of parameter fields in exemplified Section Type ZZ design

[0421] The following lists the definitions of all parameter fields used in the section description of Section Type ZZ, shown inTable Cl to Table C5.

[0422] • srsChestCompHdr: this field instructs how the O-RU will compress the channel estimates. For example, this field value indicates which compression method is used and how many bits are used to represent the channel estimates. The definition can be similar to ‘udCompHdr’ field for U-Plane data compression defined in O-RAN open fronthaul spec.

[0423] • numSrsCfgMsgs: the number of C-Plane messages that conveys the SRS configuration description of all SRS ports in the slot. This is useful when the section description for SRS configuration is so long that the number of bytes used in the C-Plane message is more than the maximum pay load size of a packet, e.g., 1500 bytes. In this case, the SRS configuration description is split into two or more C-Plane messages. With this field, the O-RU will know the number of C-Plane messages expected when receive the first C-Plane message.

[0424] • srsOnUlSlot: a one-bit flag indicates if SRS is in a UL slot or not. If SRS is in a special slot, srsOnUlSlot = 0. If SRS is in a UL slot, srsOnUlSlot = 1.

[0425] • startSrsPrb: the PRB index of the first (lowest frequency) PRB that contains SRS in any SRS symbol in the slot described in this section description. • numSrsPrb: the number of SRS PRBs of the continuous PRB range that contains SRS in any SRS symbol in the slot. It equals to endSrsPrb minus startSrsPrb plus one, where endSrsPrb represents the PRB number of the last (highest frequency) PRB that contains SRS in any SRS symbol in the slot. Alternatively, this field can be changed to endSrsPrb.

[0426] • numSrsSymbols: the total number of SRS symbols in the slot.

[0427] • numSrsClusters: the total number of SRS PRB clusters in the slot.

[0428] • srsClusterld: an identification value assigned to a PRB cluster. For example, srsClusterld = 0 for the first PRB cluster with lowest SRS frequency PRB.

[0429] • extrapolation: a one-bit flag to instruct O-RU to perform frequency-domain extrapolation in SRS channel estimation or not. If extrapolation is set to 1, the O-DU instructs the O-RU to perform frequency-domain extrapolation. If extrapolation is set to 0, the O-RU doesn’t need to do frequency-domain extrapolation.

[0430] • startPrbOfCluster: the PRB index of the first (lowest frequency) PRB of the referred SRS PRB cluster in a symbol.

[0431] • numPrbOfCluster: the number of PRBs of the referred SRS PRB cluster in a symbol.

[0432] • symbolld: an identification value representing a symbol in the slot. For example, symbolld = 0 for the first symbol in a slot and symbolld = 13 for the last symbol in a slot.

[0433] • numSrsUesOfSymbol: the total number of UEs sending SRS in the referred symbol.

[0434] • srsCombNum: Comb number for SRS used for all SRS in the referred symbol. Comb number indicates the subcarrier separation between two adjust subcarriers allocated for the SRS, as defined in 3GPP.

[0435] • srsGroupSeqHopping: a value indicates the type of SRS symbol hopping used. There are several types, e.g., ‘neither’, ‘groupHopping’, or ‘sequenceHopping’ etc., as defined in 3GPP.

[0436] • numSrsPortsOfUe: the number of SRS ports of the referred UE in the referred SRS resource identified by a srsClusterld and a symbolld. • ueCapId: UE capability identification value indicates the capability of the referred UE. The UE capabilities are 1T1R, 1T2R, 1T4R, 2T2R, 2T4R, 4T4R, etc., where xTyR means x transmit antennas and y receive antennas. Each capability is assigned to a ueCapId value.

[0437] • srsUeld: an identification value assigned to a UE that sends SRS.

[0438] • srsUeldReset: a one-bit flag indicates if the srsUeld assignment to a UE is changed. For example, srsUeldReset = 1 indicates the srsUeld assignment is changed and srsUeldReset = 0 indicates the srsUeld assignment is unchanged. This helps the O-RU to use the historical channel estimates or measurements to calculate new measurements with higher quality.

[0439] • srsSeqld: SRS sequence identity value used to generate SRS sequence, as defined in 3GPP.

[0440] • srsUePortld: an identification value assigned to a UE SRS antenna port.

[0441] • srsCyclicShift: cyclic shift offset value indicates the cyclic shift applied to the SRS sequence for a UE SRS antenna port, as defined in 3GPP.

[0442] • srsCombOffset: comb offset value indicates a frequency offset within the comb used for a UE SRS antenna port, as defined in 3GPP.

[0443] To further make it clear about the Cluster ID and Symbol ID mapping to SRS resources, more SRS configuration use case examples are provided here. Figure 15 (corresponding to figure 7 in PCT / SE2024 / 051026) shows an example with 4 SRS resources with two PRB clusters and two symbols. In each SRS resource, one or more UE SRS ports from one or more UEs can be allocated. In this example, numSrsSymbols = 2 and numSrsClusters = 2. The first PRB cluster refers full bandwidth SRS resources, spanning from PRB 0 to PRB 271. The second PRB cluster refers half bandwidth SRS resources, spanning from PRB 136 to PRB 271. In this example, two full bandwidth SRS resources (marked as grey boxes) or the two half bandwidth SRS resources (marked as white boxes) in Figure 7 may be used by a UE to send multiple SRS ports from multiple UE antennas using antenna switching. For example, a 2T4R UE sends SRS from first two UE antennas in symbol 10 and then the UE switches to the second two UE antennas to send SRS in symbol 12. In this example, symbol 11 is not used because antenna switching operation takes time and can’t be done for two adjacent symbols. In this example, the 4 SRS resources can be efficiently described with only 2 symbol IDs and 2 cluster IDs.

[0444] Figure 16 (corresponding to figure 8 in PCT / SE2024 / 051026) shows another example with a more complicated SRS configuration. In this example, there are 9 SRS resources marked as different boxes in figure 8 Following the PRB cluster definition described in this document, there are 7 PRB clusters. First PRB cluster spans from PRB 0 to PRB 135. Second PRB cluster spans from PRB 136 to PRB 203. Third PRB cluster spans from PRB 204 to PRB 271. Fourth PRB cluster spans from PRB 0 to PRB 67. Fifth PRB cluster spans from PRB 68 to PRB 135. Sixth PRB cluster spans from PRB 136 to PRB 271. Seventh PRB cluster spans from PRB 0 to PRB 271. In this example, 9 SRS resources can be efficiently described with only 4 symbol IDs and 7 cluster IDs.

[0445] Through the example shown previously, the proposed way of describing SRS configuration in C- Plane can efficiently describe all possible SRS configurations from simple cases to complicated cases in a well-structured way. And the SRS configuration of multiple SRS ports of one or more UEs in the same PRB cluster of each symbol are placed together in the C-Plane message. The O- RU can extract the SRS configuration efficiently for each SRS resource identified by a cluster ID and a symbol ID, which facilitate channel estimation operation that are normally performed within an SRS resource with the knowledge regarding how SRS is multiplexed in the SRS resource. For example, in some respects this would become more complicated if the SRS configuration is provided UE by UE, which would have lower O-RU processing efficiency than the proposed way in the document.

Claims

CLAIMS1. A method performed by an O-RAN Radio Unit, O-RU, comprising receiving a message for describing a sounding reference signal, SRS, configuration for a plurality of User Equipments, UEs, the message describing the allocation of air interface resources to a plurality of UEs for sending SRS, and / or parameters required for SRS channel estimation, and indicating one or more clusters, a cluster being a contiguous range of physical resource blocks, PRBs, in the frequency dimension wherein the message indicates for each of one or more clusters, the cluster’s location and size in the frequency dimension, wherein the PRB range of the cluster is to be used for sending SRS from one or more UEs and wherein the message indicates one or more symbols for sending SRS, the symbols beingOrthogonal Frequency Division Multiplex, OFDM, symbols.

2. A method according to claim 1 wherein the message has a section part for each of one or more SRS blocks, an SRS block being identified by a PRB cluster and a symbol, in which the SRS sequences of one or more SRS ports of one or more UEs are multiplexed.

3. A method according to claim 2 wherein each SRS block section part comprises for each UE a UE part.

4. A method according to claim 3 wherein the UE part comprises an indication for a UE of one or more of the following:- A number of SRS ports used by the UE- An identification value indicating a capability of the UE,- A UE identity value,- If the UE corresponding to the UE identity value has changed or not.- An SRS sequence identity value used by the UE to generate an SRS sequence.

5. A method according to claim 3 or 4 wherein the UE part comprises an indication of SRS allocation for the UE for the symbol and the cluster.

6. A method according to any of claim 3, 4 or 5 wherein the UE part does not comprise any indication of SRS allocation for any other UE.

7. A method according to any of claims 3-6 wherein each UE part comprises for each UE SRS port an SRS port part.

8. A method according to claim 7 wherein the SRS port part comprises indications of one or more of the following:- A cyclic shift,- A comb offset,- A UE antenna port identity.

9. A method according to claim 7 or 8 wherein the SRS port part does not contain any indication of SRS allocation for any other SRS port10. A method according to any of claims 2-9 wherein the message comprises an indication that information indicated for a UE or a UE SRS port for a symbol and a cluster is to be applied to the UE or UE SRS port also for other symbols.

11. A method according to any preceding claim when dependent on claim 4 wherein the identification value indicating a capability of the UE, ueCapId, indicates a total number of physical antennas of the UE that can be used for communicating signals12. A method according to any preceding claim when dependent on claim 4 wherein the identification value indicating a capability of the UE, ueCapId, indicates a number of transmitters of the UE for transmitting signals.

13. A method according to any of the claims 2-12 wherein the message comprises for one or more sections a first section extension part, the first section extension part comprising one or more second parts wherein each such second part comprises an indication of which third part of the message or section the second part of the section extension applies to.

14. A method according to claim 13 wherein each second part comprises a type identifier that identifies which kinds of third parts the second part applies to, such as UE, UE port, and furthercomprises one or more indications of which individual third parts of the kinds the second part applies to.

15. A method according to claim 14 where a type identifier of a second part indicates that the second part applies to the whole section and there is no further indication of individual parts.

116. A method according to any preceding claim wherein the O-RU performs SRS reception and processing based on the SRS allocation described in the message.

17. A method according to claim 16 wherein SRS processing comprises channel estimation.

18. An O-RU adapted to perform the method of any preceding claim.

19. An apparatus for functioning as an O-RU, the apparatus comprising processing circuitry and a memory, the processing circuitry configured to perform the method of any of the claims 1-17.

20. A computer program comprising program code which when run on an O-RU causes the O- RU to perform the method of any of the claims 1-17.

21. A tangible, non-transient computer-readable medium comprising instructions that, when executed by processing circuitry of an O-RU, cause the processing circuitry to perform the method of any of the claims 1-17.

22. A method performed by an O-RAN Distributed Unit, O-DU comprising transmitting to an O- RU the message received by the O-RU in any of the claims 1-17.

23. An O-DU adapted to perform the method of claim 22.

24. An apparatus for functioning as an O-DU, the apparatus comprising processing circuitry and a memory, the processing circuitry configured to perform the method of claim 22.

25. A computer program comprising program code which when run on an O-DU causes the O- DU to perform the method of claim 22.

26. A tangible, non-transient computer-readable medium comprising instructions that, when executed by processing circuitry of an O-DU, cause the processing circuitry to perform the method of claim 22.

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