Research On Optimization Of The Relay Node Location Of Cooperative Diversity

Diversity is an efficient technique to combat the negative effects of multi-path fading in wireless networks. The advantages of multiple-output-multiple-output (MIMO) systems have been widely acknowledged. But the use of MIMO is limited by the size and cost of mobile terminals. Cooperative communication is an effective method of avoiding defects of MIMO system. It enables single antenna terminal in a multi-user environment to share their antennas and other internet resources to generate a virtual antenna array. As cooperative communication makes full use of the spatial information of signal, it can save power and increase channel capacity. The choice of cooperative nodes, the nodes number and power allocation have a great effect on the system performance. The choice of relay node location is discussed in the paper.First of all, we analyze the optimization of the relay node location of cooperation diversity system under Gaussian channel, which the relay protocol was AF (Amplify and Forward) and the destination node combined the signals with MRC (Maximum Ratio Combining). The optimal location which can gain the maximum output SNR (signal to noise ratio) is derived. In the mean time, the performance of BER (bit error ratio) and channel capacity with different location of relay nodes is analyzed.Secondly, we discuss the optimization of the relay node location of cooperation diversity system under fading channel. The pdf (probability density function) of output SNR is achieved under Nakagami-m and Rayleigh hybrid channel. And the expressions of BER and outage probability is obtained through the frontal conclusions. It is notable that they are closed form solution. By computer simulation, we notice that the optimal locations which can gain the minimum BER or the minimum outage probability are close to the destination node. And they get closer to the destination node with the increase of signal SNR. The conclusions coincide with the practical.Lastly, the equivalent relationship between cooperation diversity system based on observation angles and direction finding cross location system is built. A new evaluation methodology named maximum location likelihood constraint is proposed in this paper. As it has nothing to do with the baseline length or the vertical distance between the relay node and the baseline, the new constraint is suitable for the choice of relay nodes location of mobile communication network. In addition, this method can be used in direction finding cross location, especially the sensor placement of direction finding cross location system with maneuver stations.