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WO-2026095841-A1 - SCHEDULING OF SOUNDING REFERENCE SIGNALS

WO2026095841A1WO 2026095841 A1WO2026095841 A1WO 2026095841A1WO-2026095841-A1

Abstract

There is provided techniques for SRS transmissions. A method is performed by a network node. The method comprises detecting, an SRS transmission gap for a first UE, based on detection of unused SRS ports assigned to the first UE for periodic SRS transmission. The method comprises scheduling, in an upcoming SRS transmission gap for the first UE, aperiodic SRS transmissions for at least one second UE on the detected unused SRS ports.

Inventors

  • JANSSON, Jens
  • GARCIA PERERA, José Maria
  • Jönsson, Magnus

Assignees

  • TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

Dates

Publication Date
20260507
Application Date
20241029

Claims (16)

  1. 1. A method for scheduling sounding reference signal, SRS, transmissions, wherein the method is performed by a network node (210, 700, 800), and wherein the method comprises: detecting (S102), an SRS transmission gap for a first user equipment, UE (230a), based on detection of unused SRS ports assigned to the first UE (230a) for periodic SRS transmission; and scheduling (S106), in an upcoming SRS transmission gap for the first UE (230a), aperiodic SRS transmissions for at least one second UE (230b: 230N) on the detected unused SRS ports.
  2. 2. The method according to claim 1, wherein the detection of the unused SRS ports is based on detecting absence of SRS transmission from the first UE (230a) during the SRS transmission gap.
  3. 3. The method according to claim 1 or 2, wherein the detection of the unused SRS ports is based on determining that received power associated with the first UE (230a) during the SRS transmission gap is below a threshold power value.
  4. 4. The method according to any preceding claim, wherein the detection of the unused SRS ports is based on identification of transmission gaps as configured by the network node (210, 700, 800).
  5. 5. The method according to any preceding claim, wherein the method further comprises: predicting (S104) availability of unused SRS ports for the first UE (230a) in the upcoming SRS transmission gap by recording SRS transmission state data for the first UE (230a) during previous SRS transmission gaps and feeding the SRS transmission state data into a prediction algorithm executed in the network node (210, 700, 800).
  6. 6. The method according to claim 5, wherein the SRS transmission state data is provided per time and frequency resource in the previous SRS transmission gaps, and wherein the SRS transmission state data specifies whether an SRS transmission from the first UE (230a) is present or not in the time and frequency resources in the previous SRS transmission gaps.
  7. 7. The method according to claim 5 or 6, wherein the prediction algorithm is configured to, based on the recorded SRS transmission state data, predict which SRS ports of the first UE (230a) will be unused by the first UE (230a) and when the unused SRS ports will be available in the upcoming SRS transmission gap.
  8. 8. The method according to claim 5, 6, or 7, wherein the prediction algorithm is a machine learning algorithm trained using historical SRS transmission state data recorded in previous SRS transmission gaps.
  9. 9. The method according to claim 5, 6, 7, or 8, wherein the prediction algorithm utilizes a sliding window approach to predict SRS transmission states for the first UE (230a) in at least one upcoming SRS transmission gap.
  10. 10. The method according to any preceding claim, wherein the scheduling comprises dynamically assigning the unused SRS ports to the at least one second UE (230b: 230N) based on at least one scheduling criterion.
  11. 11. The method according to claim 10, wherein the scheduling criterion pertains to at least one of: availability of the unused SRS ports in the at least one second UE (230b: 230N), communication requirements of the at least one second UE (230b: 230N).
  12. 12. The method according to claim 11, wherein the communication requirements at least pertain to prioritized transmission of the at least one second UE (230b: 230N).
  13. 13. A network node (210, 700, 800) for scheduling sounding reference signal, SRS, transmissions, the network node (210, 700, 800) comprising processing circuitry (810), the processing circuitry being configured to cause the network node (210, 700, 800) to: detect, an SRS transmission gap for a first user equipment, UE (230a), based on detection of unused SRS ports assigned to the first UE (230a) for periodic SRS transmission; and schedule, in an upcoming SRS transmission gap for the first UE (230a), aperiodic SRS transmissions for at least one second UE (230b: 230N) on the detected unused SRS ports.
  14. 14. The network node (210, 700, 800) according to claim 13, further being configured to perform the method according to any of claims 2 to 12.
  15. 15. A computer program (1020) for scheduling sounding reference signal, SRS, transmissions, the computer program comprising computer code which, when run on processing circuitry (810) of a network node (210, 700, 800), causes the network node (210, 700, 800) to: detect (S102), an SRS transmission gap for a first user equipment, UE (230a), based on detection of unused SRS ports assigned to the first UE (230a) for periodic SRS transmission; and schedule (S106), in an upcoming SRS transmission gap for the first UE (230a), aperiodic SRS transmissions for at least one second UE (230b: 230N) on the detected unused SRS ports.
  16. 16. A computer program product (1010) comprising a computer program (1020) according to claim 15, and a computer readable storage medium (1030) on which the computer program is stored.

Description

SCHEDULING OF SOUNDING REFERENCE SIGNALS TECHNICAL FIELD Embodiments presented herein relate to a method, a network node, a computer program, and a computer program product for scheduling sounding reference signal transmissions. BACKGROUND Uplink reference signals, such as sounding reference signals (SRSs) are examples of reference signals transmitted by user equipment (UE) in the uplink direction. Uplink reference signals can be used by the network, such as by one or more network nodes, to estimate the uplink channel quality over a wide bandwidth. Unlike demodulation reference signals (DM-RS), uplink reference signals are not associated with any physical uplink channels, and they support uplink channel-dependent scheduling and link adaptation. It is understood that, in order to utilize the channel sounding function, the uplink reference signals are assumed to be known by both the transmitter (i.e., the UE) and the receiver (i.e., the network node). Uplink reference signals can be used to provide information about the combined effect of multipath fading, scattering, Doppler effects, and power loss of transmitted signals. Just to give some non-limiting examples, uplink reference signals can be used to assist in codebook-based closed- loop spatial multiplexing, control of uplink transmit timing, reciprocity-based downlink (DL) precoding in multi-user multiple-input multiple-output (MIMO) system setups, and quasi co-location of physical channels and reference signals. As an example, for communication over the New Radio (NR) air interface, the SRS is an orthogonal frequency division multiplexing (OFDM) signal filled with a Zadoff- Chu sequence on different subcarriers. As a further example, with respect to the NR air interface, based on Numerology 1, a 0.5 ms long time division duplex (TDD) slot is subdivided into 14 OFDM symbols. SRS signals are transmitted during so-called special slots and can span 1, 2 or 4 OFDM symbols mapped to the last 6 OFDM symbols of each special slot. SRS is configured via Radio Resource Control (RRC) layer signaling for different resource types. As illustrated in Fig. 1, three different time-domain behaviors are supported for transmission of uplink reference signals; aperiodic transmission, semi-persistent transmission, and periodic transmission. An aperiodic transmission of uplink reference signals can be dynamically triggered by the network, for example by means of a (SRS) request field in downlink control information (DCI) or some other type of signaling on a downlink control channel (such as a physical downlink control channel, PDCCH). That is, the network node can on fine time granularity control the transmission of uplink reference signals by UEs in its served cell by sending a DCI to request UE to send uplink reference signals. The aperiodic uplink reference signals is a one-shot transmission. The UEs can be configured using RRC signaling with aperiodic uplink reference signals resources (bundled together in resource sets) which defines the frequency, sequence, and timedomain position within a slot. However, the UEs are only transmitting aperiodic uplink reference signals in slots a certain slot offset later upon where it received the trigger. A semi-persistent transmission of uplink reference signals can be activated and deactivated by the network node by sending medium access control (MAC) control elements (CEs) on a downlink data channel (such as a physical downlink shared channel, PDSCH). When a UE receives an activation command it starts to periodically transmit uplink reference signals according to a predefined periodicity and slot offset, and only stops transmitting in this manner when the UE receives a MAC CE deactivation command. Periodic transmission of uplink reference signals represent always-on signals the UEs are transmitting upon receiving RRC configuration of periodic uplink reference signals resources with a certain periodicity and slot offset. Thus, no dynamic triggering is required after configuration and the UEs do not require an activation instruction after it receives uplink reference signal resource set configuration via RRC signaling. As an example, periodic uplink reference signals can be scheduled with a periodicity that ranges from 5 ms to 320 ms. Third generation partnership program (3GPP) specifications do neither restrict nor specify how these three resource types (i.e., aperiodic transmission, semi-persistent transmission, and periodic transmission of uplink reference signals) are supported in a cell. Also other parameters can be configured for uplink reference signals. The cyclic shift allows to send multiple orthogonal signals, e.g., a cyclic shift equal to 4 allows the network node to configure four UEs in the same OFDM symbol. The transmission comb parameter defines which subcarrier are being used for uplink reference signal transmission; it also provides the network node with the capability of multiplexing two UEs by assigning them the