Comparison And Performance Analysis Of Relay Selection Algorithms In Bidirectional D2D Communication System

D2D communication technology is one of the key candidate technologies for the future 5G(5th generation mobile communication system).D2D not only improves the system's spectral efficiency and overall channel capacity,but also reduces the transmission delay and burden of the base station.In this paper,I consider the spatial distance channel model which is unusual in the field of D2D communication.Then I compare the channel capacity of D2D links under different distance models and relay selection algorithms.The first part of the article is brief summary of characteristics of D2D communication and relay technology;Secondly,I'll propose an Optimal Power Allocation and Optimal Relay Selection(OPOR)algorithm to maximize the channel capacity of D2D links under the simplified scenario of unidirectional amplifying and transmitting D2D relay communication.The comparison of the proposed algorithm,Optimal Power allocation and Random Relay selection(OPRR),Average Power Allocation and Optimal Average Power Allocation(APOR),Random Relay Selection schemes and Average Power Allocation and Random Average Power allocation and Relay Selection(APRR)schemes will show by simulation and it's clear that the proposed algorithm can improve the channel capacity of the D2D link efficiently.Finally,we come to the key part of this thesis.Two different spatial distance channel models--bidirectional symmetric channel model and bidirectional asymmetric channel model.In this paper,the OPOR scheme is applied to the two different channel models and I will describe them separately.The two models are compared with three other power allocation and relay selection schemes.It is concluded that the OPOR scheme under the two models far exceeds the other three schemes in terms of the channel capacity of the D2D link.Finally apply the four algorithms mentioned above,we compare the bidirectional asymmetric channel model with unidirectional asymmetric channel model and bidirectional symmetric channel model respectively.It turns out that the four algorithms in the bidirectional asymmetric model are superior to the other two in improving the channel capacity of the D2D link.The four algorithms in this case.In summary,the bidirectional asymmetric channel model is not only superior to the bidirectional symmetric channel model in improving the channel capacity of the D2D link,but also more practical,and has a wider range of applications.The corresponding disadvantage is that the computational complexity is higher.