Joint Sleep Scheduling Algorithms For Base Station And Relay Station In Relay-assisted Cellular Networks

With the popularity of the intelligent mobile terminals on a large scale use, the wireless mobile communication and network technology have been developed rapidly. However, due to a sharp increase of the network traffic, the traditional cellular network architecture has been difficult to meet the requirements of the growth of the network traffic. Therefore, the dense deployment of base stations and low power relay stations in the traditional cellular network is the development trend of the wireless mobile communications and network to meet the demand of higher quality of service. However, the increase of the base stations and the relay stations also poses a serious problem of energy consumption, and energy conservation and emission reduction and green communication have entered into the people’s horizons. Hence, sleep scheduling, as a typical energy saving technology in cellular networks, can effectively reduce the energy consumption and improve energy efficiency of the cellular network by turning off some idle base stations or relay stations while the network traffic is less. But few studies have focus on joint the base stations and the relay stations sleep scheduling, in view of this, jointing base stations and relay stations sleep scheduling algorithms have been studied in this thesis, so as to solve the problem of how to improve the energy efficiency of the relay-assisted cellular network under the premise of ensuring of the spectral efficiency. The main research results and innovation points are as follows:The network traffic of the relay-assisted cellular networks has temporal and spatial variation characteristic and each station belongs to both competition and cooperation relationship. Based on this, a high energy efficiency of the base stations sleep scheduling algorithm based on game theory in the relay-assisted cellular network is put forward in this dissertation. First, a distributed base stations sleep scheduling algorithm base on the temporal and spatial variations of the network traffic features is proposed, and the number of active base stations is determined each time. Then, using the interior point penalty method and Newton method,the iterative update algorithm of the optimal transmission power of the base stations is adopted based on the game theory to solve the optimization problem. The simulation results show that the proposed algorithm can determine the optimal transmission power of the base station and improve the energy efficiency.For the problem of joint the base stations and the relay stations sleep scheduling, first of all, according to the operation mode of the base stations and the relay stations, a optimization problem is established in this thesis, and the optimal problem is a mixed integer nonlinear fractional programming problem, moreover, the fact that the optimization problem is not a convex optimization problem and is difficult to be solved directly is proved. Then, by analyzing the optimization problem, we transform it into two sub-problems. Secondly, a branch and bound algorithm is proposed based on the global optimal solution of the optimization problem. Then, two heuristic algorithms are put forward: one is based on the Cellular Automata theory and the other is a greedy algorithm, and the three sleep scheduling algorithms and the exhaustive search method are analyzed and compared by simulation. The simulation results show that the proposed branch and bound algorithm can acquire the global solution and coincide with the exhaustive search and the two heuristic algorithms also obtain suboptimal solution of the optimization problem. Jointing the base stations and the relay stations sleep scheduling can reduce the energy consumption, and ensure the spectral efficiency and enhance the energy efficiency of the system.