Maximizing throughput gain via resource allocation in D2D communications

Wu et al. EURASIP Journal on Wireless Communications and Networking Maximizing throughput gain via resource allocation in D2D communications Yucheng Wu 0 Xiaocui Liu 0 Xiang He 0 Qiong Yu 0 Weiyang Xu 0 0 Chongqing University , No. 174 Shazhengjie, Shapingba, 400044 Chongqing , China By reusing the cellular resources, device-to-device (D2D) communication is becoming a very promising technology that greatly enhances the spectrum utilization. To harvest the benefits that D2D communications can offer, efficient resource allocation strategy is required to guarantee the demands of quality of service (QoS) for both cellular and D2D users. This paper proposes a resource allocation scheme to alleviate the performance deterioration of the D2D communications with spectrum reuse. To maximize the overall throughput gain, the proposed scheme is designed to reduce the rate loss of cellular users and improve the rate of D2D users simultaneously in a two-step manner. Specifically, it first calculates the reuse gain for a single D2D pair and a single cellular user. Next, a maximum weight bipartite matching is further proposed to select the reuse pair to maximize the overall network throughput gain. Numerical results demonstrate that the proposed resource allocation scheme can significantly improve the network throughput performance with average user rate guaranteed. D2D communications; Resource allocation; Optimization; Throughput gain; Rate loss 1 Introduction The device-to-device (D2D) communication is widely recognized as one of the key technology of the evolving 5G architecture due to the enhanced cellular spectrum utilization [ 1 ]. In the D2D scenario, the terminals can communicate directly with one another without the base station (BS) [ 2 ]. Therefore, the end-to-end latency can be decreased; also, the area spectral efficiency can be improved simultaneously. Therefore, the network is able to accommodate more users [ 3, 4 ]. It is worth noting that D2D communications rely on the reuse of cellular spectrum resources; thus, the performance of the cellular system will be subject to the interference incurred as a consequence. This key problem has drawn much attention from both the academic and industrial fields. In references, methods in [ 4–7 ] suggest to mitigate the interference that cellular users suffer by either limiting the D2D user’s transmit power or choosing the D2D users only in the interference limited area. However, the two approaches mentioned above cannot fully enhance the performance of D2D communications. On the other hand, the motivation of works in [ 8–11 ] is to increase the network throughput. In [8], a single D2D pair is allowed to reuse a single cellular user’s resource to maximize the throughput, and also, a closed expression of the optimal power allocation is given. In [ 9 ], the overall network throughput is maximized via reusing cellular users’ resources by multiple D2D pairs where the optimization problem is solved in three steps, i.e., access control, power allocation, and channel allocation. Moreover, the literatures in [ 10, 11 ] still consider the resource allocation with the goal of maximizing the throughput while taking the throughput gain as the access control criterion. Unfortunately, none of the above studies take into account the performance loss of cellular users incurred by the spectrum reuse. In [12], the authors propose a power management scheme for an adjacent femtocell network and formulate a non-convex optimization problem in order to maximize the capacity under the power constraints. The joint uplink subchannel and power allocation in cognitive small cells using cooperative Nash bargaining game theory is investigated in [ 13 ], where the crosstier interference mitigation, minimum outage probability requirement, imperfect CSI, and fairness are considered. In [ 14 ], the authors propose an iterative gradient user association and power allocation approach with attention to load balance constraints, energy harvesting by base stations, user quality of service requirements, energy efficiency, and cross-tier interference limits. More recently, [ 15 ] analyzes the characteristics of optimal joint power control and D2D matching strategy, based on which an energy-efficient iterative algorithm for D2D communications is proposed. For the future evolution of cellular networks, it is significant to maintain the quality of service (QoS) of both cellular and D2D users. To this end, this paper proposes a resource allocation algorithm that maximizes the throughput gain while reducing the rate loss of cellular users and increasing the rate of D2D users at the same time. It is demonstrated that the resource allocation in this study can be modeled as a mixed integer nonlinear programming (MINLP) optimization problem. To find a tractable solution, the original MINLP problem is decomposed into two subproblems, where the optimal solutions are able to be obtained in a two (...truncated)