Methods of Efficient HARQ Operation for Low Latency and High Performance Services
An efficient Hybrid Automatic Repeat Request (HARQ) operation for low-latency and high-performance services in one radio access technology (RAT) in a wireless communication network is proposed. Under the proposed single HARQ operation scheme, an adaptive HARQ-ACK feedback timing is applied based on UE conditions and UE capability to support the tradeoff between low-latency and high-performance applications. In one embodiment, UE signals the network its HARQ-ACK timing capability. Furthermore, an adaptive number of HARQ processes is applied with a fixed HARQ soft buffer size because the hardware cost for HARQ soft buffer does not linearly increase with the number of HARQ processes. In one embodiment, UE determines a nominal HARQ soft buffer size and HARQ soft buffer size for each HARQ process based on a network-configured HARQ process number.
1 . A method, comprising:
receiving a higher-layer signaling by a user equipment (UE) in a wireless communication network, wherein the higher-layer signaling indicates a number of configured hybrid automatic repeat request (HARQ) processes;
determining a nominal HARQ soft buffer size for a channel coding chain rate matching based on a UE category;
determining an HARQ soft buffer size for each HARQ process by dividing the nominal HARQ soft buffer size with the number of configured HARQ processes; and
performing HARQ operation based on the nominal HARQ soft buffer size and an actual HARQ soft buffer size of the UE.
2 . The method of claim 1 , wherein the nominal HARQ soft buffer size is determined based on an HARQ operation round-trip time and a targeted data rate.
3 . The method of claim 2 , wherein the HARQ operation round-trip time is determined according to a targeted HARQ performance.
4 . The method of claim 2 , wherein the UE also determines a second number of supported HARQ processes based on the HARQ operation round-trip time for each subcarrier spacing.
5 . The method of claim 4 , wherein the UE guarantees the target HARQ performance when the number of configured HARQ processes is smaller than the second number of supported HARQ processes.
6 . A User Equipment (UE), comprising:
a receiver that receives a higher-layer signaling in a wireless communication network, wherein the higher-layer signaling indicates a number of configured hybrid automatic repeat request (HARQ) processes;
an HARQ buffer management circuit that determines a nominal HARQ soft buffer size for a channel coding chain rate matching based on a UE category, wherein the UE also determines an HARQ soft buffer size for each HARQ process by dividing the nominal HARQ soft buffer size with the number of configured HARQ processes; and
an HARQ controller that performs HARQ operation based on the nominal HARQ soft buffer size and an actual HARQ soft buffer size of the UE.
7 . The UE of claim 6 , wherein the nominal HARQ soft buffer size is determined based on an HARQ operation round-trip time and a targeted data rate.
8 . The UE of claim 7 , wherein the HARQ operation round-trip time is determined according to a targeted HARQ performance.
9 . The UE of claim 7 , wherein the UE also determines a second number of supported HARQ processes based on the HARQ operation round-trip time for each subcarrier spacing.
10 . The UE of claim 9 , wherein the UE guarantees the target HARQ performance when the number of configured HARQ processes is smaller than the second number of supported HARQ processes.