Research On Resource Allocation Method In Efficient Collaboration Multicast

Wireless multicast technology can send the same data to users in different groups on the same spectrum. This can improve the spectrum efficiency and increase the system capacity greatly. In recent years, the wireless multicast technology and its related technology research have become more and more popular. Reliable wireless multicast provides great convenient in business such as state control, clock synchronization, video conferencing and IPTV. However, multicast service capacity is usually limited to the worst CSI(Channel State Information) among users in the group. And the system rate is reduced as the number of users increase significantly. Another method to overcome this problem is to set a default fixed rate before the transmission. But the outage probability may be very high which will lead to the low success-ratio, thus the system is unable to get the expected capacity gain.Collaborative communication combining with double time slot technology is a good way to overcome the above shortcomings. Data retransmission technology and communication collaboration are combined to achieve the balance of high system capacity and the fairness with the benefit of space diversity and time diversity.However, most of the double slot cooperative multicast technologies are based on the fixed transmit power and the fixed time slot length. With the rapid development of the green communication and the requirements of mobile endurance, the research to improve the energy efficiency of wireless multicast becomes more and more important. The research of the model of multicast which has variable power and slot allocation is of great importance.Therefore, this paper studies the double slot cooperative multicast and focuses on the variable relay selection and power allocation problem. The work is summarized as follows:Firstly, we study the main problems that exist in the current wireless multicast system. Then the double time slot retransmission multicast system principle is proposed. The typical double time slot relay selection and power allocation method is given.Then the performance analysis and comparison are presented.Secondly, we study the relay selection strategy based on variable power allocation. Then we propose a solution of relay selection and power allocation scheme based on the SNR gain. The model of variable power allocation is constructed based on the double time slot multicast system and then the problem is simplified into convex optimization problem by the semi-definite relaxation constraint scale. During the study, a simplified combining mode has been proposed to reduce the complexity of the receivers.Finally, we focus on the effect of energy efficiency about variable slot strategy. Both centralized system and distributed system model are established and studied respectively. At the end, the above research are compared and analyzed from the aspects of numerical calculation and theoretical simulation with the tool of MTALAB. The simulation results show that the variable slot strategy scheme has much better performance than traditional scheme.