US-12628021-B2 - Method and apparatus for receiver assisted transmission in shared spectrum

US12628021B2US 12628021 B2US12628021 B2US 12628021B2US-12628021-B2

Abstract

An access node such as a gNB, when determining that a communication channel in a shared spectrum is clear, may send downlink control information (DCI) triggering a user equipment (UE) to measure a resource to determine whether the communication channel is available for the UE. The UE, triggered by the DCI, may measure received energy on resource, generate a measurement report and send the measurement report to the access node. The access node may determine whether to transmit data to the UE in the communication channel based on the measurement report.

Inventors

George Calcev
Weimin Xiao

Assignees

HUAWEI TECHNOLOGIES CO., LTD.

Dates

Publication Date: 20260512
Application Date: 20230203

Claims (16)

1 . A method performed by an apparatus, the method comprising: determining whether a communication channel in a shared spectrum is clear for use when data is to be sent to a first UE by the apparatus; sending, upon determining that the communication channel is clear, a first control information message triggering the first UE to measure a layer 1 (L1) resource to determine whether the communication channel is available for the first UE; receiving, from the first UE after sending the first control information message, a first measurement report of measurement of the L1 resource; determining whether to transmit the data to the first UE in the communication channel based on the first measurement report; transmitting, based on the first measurement report that the communication channel is available for the first UE, the data to the first UE in the communication channel; receiving from the first UE a negative acknowledge (NACK) message indicating that the data has not been successfully received by the first UE; receiving, from the first UE after receiving the NACK message, a second measurement report of measurement of the L1 resource; and retransmitting the data to the first UE in the communication channel when determining, based on the second measurement report, that the communication channel is available for the first UE.
2 . The method of claim 1 , further comprising: determining that the communication channel is available after receiving the first measurement report and before transmitting the data.
3 . The method of claim 1 , wherein the data is transmitted in the L1 resource or in a subset of the L1 resource.
4 . The method of claim 1 , further comprising: sending, upon determining that the communication channel is unavailable for the first UE, a second control information message triggering the first UE to re-measure the L1 resource to determine whether the communication channel is available for the first UE.
5 . The method of claim 1 , wherein when the second UE apparatus has determined that the communication channel is unavailable for the first UE, the method further comprises: receiving, from the first UE within a preset period after receiving the first measurement report, the second measurement report; and transmitting the data to the first UE upon determining, based on the second measurement report, that the communication channel is available for the first UE.
6 . The method of claim 1 , wherein the first measurement report indicates: whether detected energy on the L1 resource or a subset of the L1 resource exceeds a threshold; whether the L1 resource or the subset of the L1 resource is idle; or the detected energy on the L1 resource or the subset of the L1 resource.
7 . The method of claim 1 , wherein the first measurement report comprises an interference measurement indicator (IMI) indicating a measurement result of the L1 resource or a subset of the L1 resource.
8 . The method of claim 1 , further comprising: transmitting information comprising any one or more of following: a resource for reporting a resource measurement; quasi co-location (QCL) information of a measurement resource; a transmission configuration indication (TCI) state indicating a QCL type of the measurement resource; a measurement time period of the resource measurement; or a measurement threshold.
9 . The method of claim 1 , wherein transmitting the first control information message comprises: transmitting the first control information message to a group of UEs including the first UE to trigger each of the UEs in the group to measure a corresponding resource to determine whether the communication channel is available for a corresponding UE.
10 . The method of claim 9 , wherein the first control information message has cyclic redundancy check (CRC) scrambled using a group radio network temporary identifier (RNTI) associated with the group of UEs, and the first control information message comprises, for each UE, one or more of following: the corresponding resource of the corresponding UE; QCL information of the corresponding resource of the corresponding UE; a measurement time window; a measurement threshold; or a resource for reporting a measurement.
11 . The method of claim 1 , wherein the first control information message further comprises a field configured to request the first UE to report an L1-IM report or a CSI-RS report on the measurement of the L1 resource.
12 . The method of claim 1 , wherein the first control information message further comprises any one or more of following: a channel state information-interference measurement (CSI-IM) time domain indicator indicating a CSI-IM configuration for an interference measurement; a parameter Periodicity-and-Offset indicating a periodicity and a timing offset for the interference measurement and reporting; or a parameter IMI Bit Length indicating a number of bits used to encode a measurement result of the interference measurement.
13 . The method of claim 1 , wherein the first control information message further includes identification information of a group of destination UEs, and the apparatus receives the first measurement report based on the first UE being in the group of destination UEs identified by the identification information in the first control information message.
14 . A method comprising: receiving, by a user equipment (UE), a first control information message triggering the UE to measure a layer 1 (L1) resource to determine whether a communication channel in a shared spectrum is available for the UE; performing, by the UE upon triggered by the first control information message, a first measurement of received energy on the L1 resource; generating, by the UE, a first measurement report based on the first measurement; transmitting, by the UE, the first measurement report; receiving, by the UE when the communication channel is available for the UE, data in the communication channel of the shared spectrum after transmitting the first measurement report; transmitting, by the UE, a negative acknowledge (NACK) message indicating that the data is not successfully received by the UE; performing, by the UE, a second measurement of received energy on the L1 resource to determine whether the communication channel is available; transmitting, by the UE, a second measurement report, the second measurement report based on the second measurement; and receiving, by the UE after transmitting the second measurement report, the data retransmitted in the communication channel of the shared spectrum.
15 . The method of claim 14 , further comprising: receiving, by the UE when the communication channel is unavailable for the UE, a second control information message triggering the UE to re-measure the L1 resource to determine whether the communication channel is available.
16 . An apparatus comprising: a non-transitory memory storage comprising instructions; and one or more processors in communication with the non-transitory memory storage, wherein the instructions, when executed by the one or more processors, cause the apparatus to perform: determining whether a communication channel in a shared spectrum is clear for use when data is to be sent to a first user equipment (UE) by the apparatus; sending, upon determining that the communication channel is clear, a first control information message triggering the first UE to measure a layer 1 (L1) resource to determine whether the communication channel is available for the first UE; receiving, from the first UE after sending the first control information message, a first measurement report of measurement of the L1 resource; determining whether to transmit the data to the first UE in the communication channel based on the first measurement report; transmitting, based on the first measurement report that the communication channel is available for the first UE, the data to the first UE in the communication channel; receiving from the first UE a negative acknowledge (NACK) message indicating that the data has not been successfully received by the first UE; receiving, from the first UE after receiving the NACK message, a second measurement report of measurement of the L1 resource; and retransmitting the data to the first UE in the communication channel when determining, based on the second measurement report, that the communication channel is available for the first UE.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is continuation of International Application No. PCT/US2021/044693 filed on Aug. 5, 2021, which claims the benefit of U.S. Provisional Application No. 63/062,204 filed on Aug. 6, 2020, which applications are hereby incorporated herein by references. TECHNICAL FIELD The present disclosure relates generally to wireless communication, and in particular embodiments, to techniques and mechanisms for receiver assisted transmission in a shared or unlicensed spectrum. BACKGROUND Licensed exempt spectrum, also known as unlicensed spectrum or shared spectrum, has recently attracted a lot of interest from cellular operators. Long Term Evolution licensed assisted access (LTE-LAA) was specified in 3GPP LTE releases (Rel) 13 and 14. More recently in New Radio Unlicensed (NR-U), the operation in unlicensed spectrum (or shared spectrum) was specified in release 16 (3GPP TS 38.213, which is hereby incorporated herein by reference in its entirety) for 3GPP New Radio (NR). 3GPP and IEEE technologies operating in unlicensed spectrum use listen before talk (LBT) channel access. In certain regions, such as European Union (EU) and Japan, a LBT rule is generally enforced by spectrum regulators to reduce interference risks and to offer a fairer coexistence mechanism. The LBT mechanism requires a transmitter to check, before a transmission, if there are other occupants of a channel and postpone the transmission if the channel is occupied. In particular, the LBT rule in EU, specified in European Telecommunications Standards Institute (ETSI) European Standard (EN) 301893 for 5 GHz band, uses clear channel assessment (CCA) to determine if a channel is available for transmission. CCA checks if energy received on a channel is above a CCA threshold. If the energy detected exceeds a CCA threshold, the channel is considered in use (busy), otherwise, the channel is considered idle. If the channel is idle, a transmitter can transmit for a duration of a channel occupancy time (COT) in a bandwidth that is at least a portion, e.g., 80%, of a total channel bandwidth. The maximum COT duration for a transmission burst is also specified in ETSI EN 301893, which is hereby incorporated herein by reference in its entirety. The maximum COT (MCOT) duration adopted in 3GPP NR-U Rel 16 (TS 37.213, which is hereby incorporated herein by reference in its entirety) is a function of a channel access priority class (CAPC). As defined in TS 37.213, for determining a COT, if a transmission gap (an interval between consecutive transmissions) is less than or equal to 25 us, the transmission gap duration is counted in the COT. A transmission burst is defined as a set of transmissions with gaps (i.e., transmission gaps) no more than 16 us, and if the gaps are greater than 16 us, the set of transmissions are considered separate. 3GPP Rel 16 (TS 37.213) defines several types of channel access in unlicensed spectrum, for downlink (DL) and uplink (UL). In Type 1 DL channel access, a gNB may transmit after first sensing a channel to be idle during sensing slot durations of a defer duration Td and after a randomly initiated counter N, which is decremented in each idle sensing slot, is zero. A sensing slot duration may be 9 us. Type 1 DL channel access may be used before starting a new COT, where the COT duration can be up to 10 ms depending on traffic priority. Type 2 DL channel access includes a deterministic duration of channel sensing, during which a channel needs to be sensed as idle. Type 2 DL channel access includes Type 2A, Type 2B and Type 2C channel accesses. Type 2A channel access allows a transmission if the channel is sensed idle for at least a sensing interval of 25 us prior to transmission. Type 2B channel access allows a transmission if the channel is sensed idle for at least a sensing interval of 16 us prior to transmission. Type 2C channel access allows a transmission for a duration of no more than 584 us without channel sensing prior to transmission. Type 2A DL channel access procedures are applicable in shared COT following a user equipment (UE) transmission, and for transmissions that includes a discovery burst with a duration of at most 1 ms and a duty cycle at most 1/20. Type 2B or Type 2C DL channel access procedures are applicable following transmission(s) by a UE after a gap of 16 us or up to 16 us, respectively, in a shared channel occupancy. Similarly to the DL channel access types, TS 37.213 defines UL channel access procedures, where Type 1 UL channel access is based on sensing channel being idle for a defer fixed duration Td and then until a random backoff counter N decremented for each idle sensing slot reaches zero, as in Type 1A DL channel access. Type 2 UL channel access requires that the channel to be sensed as idle for a fixed (deterministic) duration before transmissions, where Type 2A UL channel access requires at least a 25 us channel idle duration before transmission, and Type