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EP-4742553-A1 - METHOD FOR HANDLING CHANNEL STATUS INFORMATION REPORT AND USER EQUIPMENT

EP4742553A1EP 4742553 A1EP4742553 A1EP 4742553A1EP-4742553-A1

Abstract

The embodiments of the disclosure provide a handling a channel status information, CSI, report and a user equipment, UE, (200). The method includes: determining (S310) a first CSI according to a first set of reference signal, wherein the first set of reference signal is determined according to a first configuration transmitted by a network device; transmitting (S320) the first CSI according to the first configuration; determining (S330) a second CSI according to a second set of reference signal; performing (S340) a cell switch with a target candidate cell according to a first information transmitted by the network device; in response to determining that the second CSI does not comprise invalid CSI, transmitting (S360) the second CSI to the target candidate cell; and in response to determining that the second CSI comprises at least one invalid CSI, transmitting (S370) the second CSI comprising at least one CQI corresponding to a lowest index to the target candidate cell.

Inventors

  • LEE, CHIEN-MIN
  • LO, LI-CHUNG
  • CHEN, JEN-HSIEN
  • WANG, HUNG-HSIANG

Assignees

  • Industrial Technology Research Institute

Dates

Publication Date
20260513
Application Date
20251029

Claims (15)

  1. A method for handling a channel status information, CSI, report used by a user equipment, UE, (200) the method being characterized in comprising: determining (S310) a first CSI according to a first set of reference signal, wherein the first set of reference signal is determined according to a first configuration transmitted by a network device; transmitting (S320) the first CSI to the network device according to the first configuration; determining (S330) a second CSI according to a second set of reference signal; performing (S340) a cell switch with a target candidate cell according to a first information transmitted by the network device; in response to determining that the second CSI does not comprise invalid CSI, transmitting (S360) the second CSI to the target candidate cell; and in response to determining that the second CSI comprises at least one invalid CSI, transmitting (S370) the second CSI comprising at least one channel quality indicator, CQI, corresponding to a lowest index to the target candidate cell.
  2. The method according to claim 1, wherein the second set of reference signal is determined according to a second information.
  3. The method according to claim 2, wherein the first information and the second information are transmitted by a same information by the network device.
  4. The method according to claim 2, wherein the second information is associated with the first CSI; wherein the second information is associated with at least one of cell identity and at least one first signal resource indicator.
  5. The method according to any one of claims 1 to 4, wherein each of the first set of reference signal is respectively associated with a candidate cell index.
  6. The method according to any one of claims 1 to 4, wherein each of the second set of reference signal respectively has a quasi-co-location relationship with a synchronization signal block, SSB, index.
  7. The method according to any one of claims 1 to 4, wherein the first CSI comprises at least one of following: a plurality of second signal resource indicator; a reference signal received power, RSRP; or at least one differential RSRP.
  8. The method according to any one of claims 1 to 4, wherein the first CSI comprises a first number of different signal resource indicators for each of a second number of candidate cells; wherein the first number and the second number are configured by a higher layer signal.
  9. The method according to any one of claims 1 to 4, wherein the second CSI comprises at least one of following: a third signal resource indicator; CQI; precoding matrix indicator, PMI; or rank indicator, RI.
  10. The method according to claim 2, wherein the second CSI is transmitted to the target candidate cell using a first physical uplink shared channel, PUSCH, after receiving the second information.
  11. The method according to any one of claims 1 to 4, wherein the second CSI is carried in a CSI report, and the CSI report is configured as aperiodic; wherein the first CSI is associated with a plurality of candidate cells; wherein the second CSI is associated with the target candidate cell.
  12. The method according to any one of claims 1 to 4, wherein the second set of reference signal is determined according to a threshold value.
  13. The method according to any one of claims 1 to 4, wherein the second CSI is associated with a third number of candidate cell and a fourth number of reference signal for each of the third number of candidate cell.
  14. The method according to any one of claims 1 to 4, further comprising: transmitting a capability information to the network device, wherein the capability information comprises at least one of following: whether the UE supports a first CSI measurement and a first CSI report associated with the first CSI for at least one candidate cell; whether the UE supports a second CSI measurement and a second CSI report associated with the second CSI for the at least one candidate cell; the second CSI measurement is performed before or after receiving a cell switch command; a maximum number of candidate cells for the first CSI measurement or the second CSI measurement; a maximum number of reference signal per cell or per SSB for the first CSI measurement or the second CSI measurement; capability regarding at least one of RI, CQI, PMI and a wideband indication; whether inclusion of a current special cell, SpCell, in the first CSI report is supported.
  15. A user equipment, UE, (200) comprising: a transceiver (202); and a processor (204), coupled to the transceiver (202) and characterized by being configured to perform: determining (S310) a first CSI according to a first set of reference signal, wherein the first set of reference signal is determined according to a first configuration transmitted by a network device; controlling the transceiver to transmit (S320) the first CSI to the network device according to the first configuration; determining (S330) a second CSI according to a second set of reference signal; performing (S340) a cell switch with a target candidate cell according to a first information transmitted by the network device; in response to determining that the second CSI does not comprise invalid CSI, controlling the transceiver to transmit (S360) the second CSI to the target candidate cell; and in response to determining that the second CSI comprises at least one invalid CSI, controlling the transceiver to transmit (S370) the second CSI comprising at least one CQI corresponding to a lowest index to the target candidate cell.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The disclosure generally relates to a communication mechanism, in particular, to a method for handling a channel status information (CSI) report and a user equipment (UE). 2. Description of Related Art In fifth-generation (5G) mobile communication systems, user equipment (UE) may perform handover (or cell switch) among multiple cells to maintain service continuity. Compared to Layer 3-based mobility procedures, Layer 1/Layer 2 Triggered Mobility (LTM) offers advantages in terms of reduced handover (or cell switch) latency and interruption time, and is therefore considered a promising low-latency mobility solution. However, in existing LTM procedures, Layer 1 (L1) measurements are limited to those based on Synchronization Signal Blocks (SSBs). Currently, the SSB-based L1 measurement procedure involves the UE receiving and evaluating SSB signals from multiple cells and reporting a subset of SSB Resource Indicators (SSBRIs) based on signal strength metrics such as Reference Signal Received Power (RSRP). While this provides basic channel quality information, it remains insufficient for accurate and timely channel estimation immediately after cell switching. As a result, downlink modulation and resource allocation may not be optimally adjusted, leading to degradation in User Perceived Throughput (UPT). Moreover, existing systems do not incorporate measurement of Channel State Information Reference Signals (CSI-RS) into the L1 procedures of LTM, which limits the gNB's ability to obtain accurate channel state information immediately following the cell switch. This limitation negatively impacts the performance of link adaptation and beam management, especially in scenarios involving high mobility or densely deployed multi-cell environments. See FIG. 1, which shows a schematic diagram of effects of applying the CSI feedback. In FIG. 1, it is assumed that the UE performs the cell switch operation from the source cell to the target cell at the time point T01. As can be seen from FIG. 1, if the CSI feedback information (e.g., channel quality indicator (CQI), precoding matrix indicator (PMI), CSI-RS resource indicator (CRI), layer indicator (LI), rank indicator (RI), etc.) associated with the target cell is not available before the cell switch operation, the User Perceived Throughput (UPT) of the UE would experience a great degradation (e.g., about 75%) for a while after the cell switch operation. On the other hand, if the CSI feedback associated with the target cell is available before the cell switch operation, the UPT of the UE would not experience the same degradation after the cell switch operation. Accordingly, there is a need for a technical solution that incorporates CSI-RS measurement and reporting into LTM procedures, thereby enabling improved channel state estimation following cell switch and enhancing overall system throughput and user experience. SUMMARY OF THE INVENTION Accordingly, the disclosure is directed to a method for handling a CSI report and a UE, which can be used to solve the above technical problem. The embodiments of the disclosure provide a method for handling a CSI report used by a UE. The method includes: determining a first CSI according to a first set of reference signal, wherein the first set of reference signal is determined according to a first configuration transmitted by a network device; transmitting the first CSI to the network device according to the first configuration; determining a second CSI according to a second set of reference signal; performing a cell switch with a target candidate cell according to a first information transmitted by the network device; in response to determining that the second CSI does not comprise invalid CSI, transmitting the second CSI to the target candidate cell; and in response to determining that the second CSI comprises at least one invalid CSI, transmitting the second CSI comprising at least one CQI corresponding to a lowest index to the target candidate cell. The embodiments of the disclosure provide a UE, including a transceiver and a processor. The processor is coupled to the transceiver and configured to perform: determining a first CSI according to a first set of reference signal, wherein the first set of reference signal is determined according to a first configuration transmitted by a network device; controlling the transceiver to transmit the first CSI to the network device according to the first configuration; determining a second CSI according to a second set of reference signal; performing a cell switch with a target candidate cell according to a first information transmitted by the network device; in response to determining that the second CSI does not comprise invalid CSI, controlling the transceiver to transmit the second CSI to the target candidate cell; and in response to determining that the second CSI comprises at least one invalid CSI, controlling the transceiver to transmi