Research On Interference Coordination In Cellular And Device-To-Device Communication Network

With the dramatic growth of smart mobile devices and network traffic, the next generation of mobile communication network is facing several challenges, i.e., spectrum efficiency, energy efficiency and network coverage. The3rd Generation Partnership Project (3GPP) which leads the next generation of wireless communication network technology has raised a lot of solutions and related technical discussions for the issues, including Device-to-Device (D2D) communication technology. D2D communication technology has many advantages such as improving cell capacity, lowering transmission power of terminals and base stations, alleviating the load for base station, enhancing the security of communication, etc. However, D2D users which reuse cellular users’ resources to improve resource utilization cell will inevitably interfere with cellular users. On the premise that the interference problem be well handled, can the D2D communication achieve all the aforementioned benefits in the hybrid communication network.In order to solve the interference problems introduced by D2D communication into the cellular system, this paper investigates the interference coordination mechanism in cellular and D2D hybrid communication network and analyzes the causes of interference. Two interference coordination methods which respectively focus on the system capacity performance and outage probability performance are proposed, both of which have good interference coordination effect. The main work of this paper is as follows:Firstly, this paper proposes a joint resource and power allocation algorithm for interference coordination in hybrid cellular and D2D communication network. The algorithm consists of three phases. In the first stage, an interference graph based algorithm is proposed to divide the two kinds of users to different clusters. Thus the multi-user interference is preliminarily coordinated. In the next stage, the instantaneous channel state information (CSI) of each communication link is considered to decide the assignment of the resource block and to achieve an optimal system capacity. The minimum communication rate is also considered for all the users. In the third stage, the lower and upper bound of the optimization function are proved to be semi-concavities functions, thus the power allocation problem becomes a convex optimization problem and it is solved by a low complexity gradient method. Finally, we present numerical simulation results to verify the proposed algorithm. With remarkably reduced complexity, the proposed three-phase algorithm achieves a near-optimal performance in terms of the system capacity.Secondly, this paper presents another interference coordination mechanism based on users’ outage probability in the hybrid communication network. The influence of user’s location is studied to analyze the distribution of interference. The first step of the interference coordination is to decide the D2D users’ transmission power. On the premise that the outage probability of the cellular users is guaranteed above a certain threshold, D2D users’transmission power is restricted to avoid severe interference to the cellular users. In the next stage, D2D users choose the resource of the cellular users which leads to a minimum outage probability. Finally, the proposed mechanism and other mechanisms are simulated and compared. It shows that the proposed interference coordination mechanism has better outage probability performance.