An Autonomous Interference Avoidance Scheme for D2D Communications through Frequency Overhear-ing in OFDM System

Abstract

Device to device (D2D) communication user equipment (UE) transmits data signals to each other over a direct link instead of through the BS, which differs from femto cell where users communicate with the help of small low power cellular base stations. Since D2D has many advantages such as improvement of data rate, spectral efficiency, usability in disaster situations, and overload mitigation of base stations D2D has been spotlighted for the next generation communication technology, especially in the 5G technology. However, disadvantages remain such as interference with cellular in case of spectrum sharing mode where cellular and D2D communicate using the same resource. In the worst case, the cellular system experiences outage if the interference from the D2D pair is too much which is a main concern in this paper. The processes of D2D can be divided into three: peer discovery, link establishment, and data transmission. In this paper, we deal with the link establishment and data transmission procedures. Assuming that D2D pair is already discovered each other. When frequency resources are persistently allocated in or-thogonal frequency division multiplexing (OFDM) time division duplexing (TDD) sys-tem, we propose an autonomous interference avoiding scheme for D2D communication where resources are opportunistically shared with uplink cellular users. It does not allo-cate subchannels that nearby cellular users currently use via overhearing the signal power of uplink cellular users and calculating the interference in the frequency domain without the use of explicit control channels. With the proper decision of parameters such as the threshold, the proposed scheme can increase the total system throughput at the cost of small cellular throughput. The performance of the proposed scheme is shown through computer simulation, where a tradeoff between total system throughput and cellular only throughput are observed, and an appropriate threshold accepting new link needs to be optimized. In addi-tion, success probability of the overhearing operation is analyzed and compared to simulation results. ⓒ 2014 DGIST