Patent ID: 9538490
Date: 2017-01-03
CPC Classifications: H04W

Claim:
1. A method of performing uplink synchronization in a wireless communication system, the method comprising: transmitting, by a user equipment (UE), a first random access preamble to a network; receiving, by the UE, a random access response comprising a timing alignment command from the network, wherein the random access response is identified by an identifier associated with a radio network temporary identity; starting, by the UE, a time alignment timer after receiving the timing alignment command; stopping, by the UE, the time alignment timer when contention resolution between the UE and the network is considered not successful; and if the UE stops the time alignment timer, transmitting, by the UE, a second random access preamble to the network or reporting, by the UE, to a radio resource control (RRC) layer that the contention resolution is considered not successful.