Relay Selection And Study Of Energy Efficiency In The Two-way Collaboration System

MIMO can give a sharp rise on capacity in the wireless mobile communication system,but implementation of MIMO technology is high complexity,expensive,difficult to practical at present.Collaborative communication which can improve the capacity of wireless mobile communication system is another effective way, it is in multi-user communication environment,the user can share the aerial of other mobile users to produce one which is similar to a virtual MIMO antenna input/output communication system environment,To obtain the corresponding spatial diversity, a deeply increase in wireless mobile communication system transmission performance and capacity.At present.Collaborative communication which is considered as the key technology of next generation network has been widely studied, especially when direct passing link status is poorer it can play a important role.This paper research a higher spectrum efficiency one which is named wireless two-way relay system, and explores the two-way relay selection in the cognitive network.each user node is provided by the battery energy in the actual wireless communication system,frequently replacing battery is not convenient, energy efficiency is more and more focus by people,this paper put forward a new energy efficient solutions that aiming to improve energy efficiency.which studies are follows:1. The paper briefly expounds the basis theory of cooperative communication knowledge,including common cooperative diversity technology,such as time diversity and frequency diversity and space diversity, it also analyzes the two-way and one-way with AF and DF protocol, And also analyzes the communication performance.2.The paper analyzes several existing relay selection algorithm in detail,one of which based on the signal to noise ratio and channel gain two-way relay system always adopt collaborative transmission relay selection algorithm, it will reduce the degree of freedom system utilization to a certain extent.Based on this,this article innovation point is to study the problem of "when tocollaborate, the direct transmission link between source node and destination node has been taken into account.Through comparing the relay link channel gain and direct link channel gain whether we need to implement a collaborative communication, when the two-way link channel gain lower than direct link, the system will take direct transport links;Otherwise adopt the relay cooperative communication link.so this strategy can increase the total rate of information effectively.Simulation shows that this scheme is superiority,the total rate is better than the other relay scheme.3 In the cognitive network which has completed the spectrum, through the best relay selection,through reasonable system of power allocation under the limit of power,it can achieve maximum total rate.and Put forward the system average total rate for upper objective function of optimal power allocation(OPA) scheme,To analysis the relay,it is concluded that the optimal average total rate of system, and the introduction of Lagrange convex optimization and simulation,simulation results also improved the total rate.4 This system model adopts the foundation of two-way transmission model of collaboration,considering the non-ideal transmitter and power consumption on the basis of dynamic circuit,energy efficiency of two-way link is not always higher by analyzing the energy efficiency of direct link(DT) and two-way collaboration link(TWRT),it is concluded that it has a equal value which is that traditional energy efficiency is equal to the two-way, through the dichotomy solving this threshold method,and put forward an efficient adaptive schemes, this scheme is based on the maximum energy efficiency to change the mode, by the system demand for rate R thus further improving energy efficiency.Simulation indicate that rate within a certain range of change,the system adopt efficient strategy of system energy efficiency is always the best.