DRX and HARQ Operations in Adaptive TDD Systems
A method of DRX and HARQ operation enhancement in adaptive TDD systems is proposed. A UE establishes a radio resource control (RRC) connection with a base station in a mobile communication network. The UE obtains adaptive time division duplex (TDD) configuration information from the base station, wherein the adaptive TDD configuration information comprises an actual TDD configuration and/or a reference TDD configuration. The UE performs a Hybrid Automatic Repeat Request (HARQ) round trip time (RTT) timer counting for each downlink (DL) HARQ process based on the adaptive TDD configuration information. The UE can avoid the potential misunderstanding between eNB and UE regarding HARQ RTT timing when TDD configuration changes.
1 . A method comprising:
(a) establishing a radio resource control (RRC) connection with a base station by a user equipment (UE) in a mobile communication network;
(b) obtaining adaptive time division duplex (TDD) configuration information from the base station, wherein the adaptive TDD configuration information comprises an actual TDD configuration and/or a reference TDD configuration; and
(c) performing a Hybrid Automatic Repeat Request (HARQ) round trip time (RTT) timer counting for each downlink (DL) HARQ process based on the adaptive TDD configuration information.
2 . The method of claim 1 , wherein the obtaining in (b) involves obtaining a TDD configuration from broadcasted system information block.
3 . The method of claim 1 , wherein the obtaining in (b) involves obtaining a TDD configuration from dedicated signaling.
4 . The method of claim 1 , wherein the performing in (c) involves setting a duration of the HARQ RTT timer to k+4 subframes, wherein k is the number of subframes between a previous downlink transmission and a subsequent uplink transmission for HARQ feedback, and wherein k depends on the actual TDD configuration.
5 . The method of claim 1 , wherein the performing in (c) involves setting a duration of the HARQ RTT timer to k′+4 subframes, wherein k′ is the number of subframes between a previous downlink transmission and a subsequent uplink transmission for HARQ feedback, and wherein k′ depends on a combination of an old TDD configuration and a new TDD configuration.
6 . The method of claim 5 , wherein k′ is determined by a predefined rule.
7 . The method of claim 5 , wherein the subsequent uplink transmission for HARQ feedback occurs in the nearest subsequent uplink subframe, and wherein k′ is greater than or equal to four.
8 . The method of claim 1 , wherein the performing in (c) involves counting the HARQ RRT timer for each DL HARQ process according to the reference TDD configuration.
9 . The method of claim 8 , wherein the reference TDD configuration comprises a downlink (DL) reference configuration, and wherein the DL reference configuration is with the most schedulable DL subframes.
10 . The method of claim 1 , wherein the actual TDD configuration is obtained via dedicated signaling, and wherein the reference TDD configuration is obtained via system information broadcasting.
11 . A user equipment (UE), comprising:
a radio resource control (RRC) module that establishes an RRC connection with a base station in a mobile communication network;
an adaptive time division duplex (TDD) configuration management module that obtains adaptive TDD configuration information, wherein the adaptive TDD configuration information comprises an actual TDD configuration and/or a reference TDD configuration; and
a Hybrid Automatic Repeat Request (HARQ) operation module that performs HARQ round trip time (RTT) timer counting for each downlink (DL) HARQ process based on the adaptive TDD configuration information.
12 . The UE of claim 11 , wherein the UE obtains a TDD configuration from broadcasted system information block.
13 . The UE of claim 11 , wherein the UE obtains a TDD configuration from dedicated signaling.
14 . The UE of claim 11 , wherein the UE sets a duration of the HARQ RTT timer to k+4 subframes, wherein k is the number of subframes between a previous downlink transmission and a subsequent uplink transmission for HARQ feedback, and wherein k depends on the actual TDD configuration.
15 . The UE of claim 11 , wherein the UE sets a duration of the HARQ RTT timer to k′+4 subframes, wherein k′ is the number of subframes between a previous downlink transmission and a subsequent uplink transmission for HARQ feedback, and wherein k′ depends on a combination of an old TDD configuration and a new TDD configuration.
16 . The UE of claim 15 , wherein k′ is determined by a predefined rule.
17 . The UE of claim 15 , wherein the subsequent uplink transmission for HARQ feedback occurs in the nearest subsequent uplink subframe, and wherein k′ is greater than or equal to four.
18 . The UE of claim 11 , wherein the UE counts the HARQ RRT timer for each DL HARQ process according to the reference TDD configuration.
19 . The UE of claim 18 , wherein the reference TDD configuration comprises a downlink (DL) reference configuration, and wherein the DL reference configuration is with the most schedulable DL subframes.
20 . The UE of claim 11 , wherein the actual TDD configuration is obtained via dedicated signaling, and wherein the reference TDD configuration is obtained via system information broadcasting.