Patent ID: 8867562
Filing Date: 2014-10-21
Classification: H04L,H04W

Abstract:
1. A method of performing a random access procedure in a wireless communication system using a number of orthogonal frequency division multiplexing (OFDM) symbols, the method performed by a user equipment (UE) and comprising: transmitting a first random access preamble to a base station (BS); receiving, in response to the first random access preamble, back-off interval information included in a random access response from the BS; determining a lower bound of a back-off time value and an upper bound of the back-off time value based on the back-off interval information; and transmitting a second random access preamble to the BS, wherein the transmission of the second random access preamble is delayed according to the back-off time value which is selected between the lower bound of the back-off time value and the upper bound of the back-off time value, wherein the lower bound of the back-off time value is non-zero, wherein the back-off time value is randomly selected according to a uniform distribution between the lower bound of the back-off time value and the upper bound of the back-off time value, wherein the back-off interval information is included in a media access control (MAC) protocol data unit (PDU) of the random access response, and wherein an indication field is included in a first sub-header of a MAC header, and the indication field indicates whether the lower bound of the back-off time value is determined by a multiplication of a predetermined fraction and the back-off interval information of the back-off time value which is determined based on the upper bound of the back-off time value.