Studies On Resource Sharing For Device-To-Device Comunication In Heterogeneous Networks

Recently,with the increasing demand of user equipments(UEs) and applications in cellular networks, more and more advanced wireless systems have been designed to obtain a higher data rate. However, the available spectrum resources are becoming scarce. Therefore, a variety of researchers have put emphasis up on increasing spectral efficiency and suppressing interference. Device-to-Device(D2D) communications and femtocells in cellular networks can share resources with cellular users in a nonorthogonal manner, which can take advantage of improving network capacity and increasing resource utilization. In this case, the interference among the three-tier network is complicated and may degrade the system performance seriously. Thus it is a significance challenge in designing the heterogeneous network and has received much attention. For this reason, It is important to design an appropriate resource sharing strategy to minimize the intra-system interference.Based on the key techniques of D2 D communications, this paper focused on studying the wireless resource management mechanism, in order to solve the wireless resource sharing problem and the interference coordination problem. This paper includes the following researches:1. Based on the optimal power allocation strategy, we propose a resource sharing strategy. First, we design an optimal transmit power assignment strategy to improve the throughput of the D2 D link, meanwhile guaranteeing the service quality for both the cellular system and femtocell system. What’s more, we propose two suboptimal power allocation strategies. On this basis, we propose a resource allocation strategy in a multi-femtocell system to maximize the throughput of D2 D pairs with the smallest possible total power consumption. Simulation results show the proposed intelligent algorithm can both improve the throughput of D2 D user and reduce total power consumption of the network.2. We construct a Stackelberg game framework for power allocation problem of D2 D communication and Femtocell network in heterogeneous Macro/Femto/D2 D wireless system and propose an iterative algorithm for equilibrium. First, we work out the optimal transmit power by analyzing the procedure of the leader and the followers. Then we put forward an iterative algorithm to allocate power for D2 D transmitters and Femtocell users. Simulation results illustrate that the proposed method can effectively promote the throughput of users.3. We propose a resource allocation strategy based on the distance restriction to manage the interference among macrocell, femtocell and D2 D communications. First, by defining the interference constraint area, the QoS of users is guaranteed. After that, the resources are assigned to D2 D and femtocell users to improve the sum rate of the network. The simulation results show that the proposed algorithm not only guarantees the communication quality of the cellular network, but also improves the throughput of the network. What’s more, the BS overhead is decreased.