Patent ID: 9681403
Date: 2017-06-13
CPC Classifications: H04W

Claim:
1. A method of managing uplink time alignment in a wireless communication system, performed by a user equipment (UE), the method comprising: receiving, by the UE from a base station, a timing advance command (TAC); upon receiving the TAC, starting, by the UE, a time alignment timer (TAT) and applying the received TAC, wherein the TAT is used to control how long the UE is considered uplink time aligned; transmitting, by the UE to the base station, a TAC request message that requests an extension or expiry of uplink time alignment, wherein the transmission of the TAC request message to the base station is prohibited during a first prohibit time period indicated by a first prohibition timer set with a prohibition timer value related to the transmission of the TAC request message, wherein the TAC request message includes a suggested TAC value generated by the UE, and wherein the TAC request message is transmitted in a form of a medium access control (MAC) control element (CE), and a new logical channel identifier (LCID) field is allocated for the MAC CE; transmitting, by the UE to the base station, an expiry request message that requests the expiry of uplink time alignment, wherein the expiry request message includes request information indicating how long the TAT will run before expiring; receiving, by the UE from the base station, an expiry response message in response to the expiry request message while the TAT is running; and upon receiving the expiry response message, stopping the TAT and releasing uplink resources, wherein the transmission of the expiry request message to the base station is prohibited during a second prohibit time period indicated by a second prohibition timer set with a prohibition timer value related to the transmission of the expiry request message, and wherein the request information included in the expiry request message indicates a type of an application that needs an extension or expiry of an uplink synchronized state.