Patent ID: 9559822
Date: 2017-01-31
CPC Classifications: H04L,H04W

Claim:
1. A method in a mobile node, of determining when to transmit a signal, wherein the mobile node operates in a wireless communication system comprising a first cell and a second cell, where the mobile node is synchronized to the first cell, the method comprising: determining a timing reference based on a reception of a downlink transmission in the first cell; transmitting the signal, to be received in the second cell, at a point in time based on the timing reference and a timing advance value of the first cell; receiving a timing advance value for the second cell in response to the transmitted signal; using the received timing advance value for the second cell for further transmissions of signals to be received in the second cell; and determining a time of start of transmission of a downlink sub-frame in the second cell, wherein the determining the time of start of transmission of the downlink sub-frame in the second cell is based on the timing reference and the timing advance value for the second cell, wherein the timing advance value for the second cell is half the timing advance value of the first cell plus an offset value, and wherein the offset value corrects asymmetry in propagation times between uplink and downlink transmissions.