Resource allocation for multiple-pair D2D communications in cellular networks

Device-to-device (D2D) communication is proposed as a vital technology to increase the system capacity and spectral efficiency, while reducing the latency and energy consumption. Existing researches usually investigate the resource allocation for D2D communications underlaying the orthogonal frequency division multiple access (OFDMA) based cellular network, un- der the scenario in which spectrum can be spatially reused. However, most of these researches did not consider individual power constraint of each D2D device (e.g. a smart phone), which is generally limited for every device. Therefore, with the consideration of the transmit power limitation per device, the resource allocation issue is investigated in this paper for the multiple D2D pairs underlaid OFDMA-based cellular system with the target of achieving the optimal system throughput. By exploring the relationship between the number of subcarriers per D2D pair and maximum power constraint for each D2D pair, a sub-optimal joint power and subcarrier allocation algorithm is proposed to achieve high spectral efficiency with low complexity. Simulation results demonstrate that the performance of the proposed algorithm is very close to the optimal solution obtained by global exhaustive searching method. Meanwhile, the effect of number of subcarriers allocated to each D2D pair on the system performance is analysed through simulation results.