Patent ID: 9014062
Filing Date: 2015-04-21
Classification: H04L,H04W

Abstract:
1. A method of processing hybrid automatic repeat request (HARQ) and adaptive transmission of a device-to-device (D2D) link when D2D link communication is performed in a time-division duplex (TDD) cellular communication system or a frequency-division duplex (FDD) cellular communication system using one of an uplink band and a downlink band, wherein an operation method of user equipment (UE) comprises: (a) receiving an initial transmission mode (TM) and transmission power for the D2D link from a base station, and performing data transmission through the D2D link; (b) determining, at the UE, a TM and transmission power of a succeeding subframe, or receiving a TM control value and a transmission power control value from counterpart UE of the D2D link and determining the TM and the transmission power of the succeeding subframe, the TM control value and the transmission power control value being continuously received from the counterpart UE at given periods or received only the TM and the transmission power need to be changed; (c) performing the data transmission to the counterpart UE using the determined TM and transmission power, wherein (b) and (c) are repeated; and (d) requesting the base station to replace the D2D link with the counterpart UE with a cellular link when the counterpart UE repeatedly fails in receiving data transmitted in (c) a predetermined number of times or more during a predetermined time period.