On The Performance Analysis Of COGNITIVE-BASED D2D Communications Over Generalized Fading Channels

Device-to-Device(D2D)communication,a proximity communication technology,can realize end-to-end communication by reusing the resource of the users within a macro cell.A macro cell utilizes the D2 D communication technology,which can greatly improve the spectrum utilization and improve the overall performance of the system.But it will also produce interference to cellular system.Therefore,this thesis mainly investigates D2 D communication(secondary user)using the underlay spectrum sharing technology mode of cognitive radio(CR)to coexist with the cellular(primary user)by reusing the radio resource of cellular in the hybrid networks composed of D2 D communication and cellular communication.At the same time,the interference temperature Q is added to primary user to reduce the interference of the D2 D users.In this case,we study the communication performance of D2 D communication over generalized-K and generalized ?-? fading channel,such as outage probability,mean capacity and bit error rate.According to the contents of the study,the thesis is as follows:Firstly,we combined the features of cognitive radio(CR)and D2 D communication technology features and present a performance analysis based on cognitive D2 D communication in cellular system.By constructing the system model,the communication performance formula of D2 D users is deduced.Secondly,we study the communication performance of D2 D communication over generalized-K and generalized ?-? fading channel.Generalized-K fading model describes accurately composite multipath and shaodwing fading channels which are widely encountered in real-world environments.But the generalized ?-? distribution fading model can accurately describes the characteristics of small-scale fading of wireless signals in non-line-of-sight communication.In this thesis,the graph of the probability density function and the cumulative distribution functions are given,and the closed-form expressions of the communication performance formula of D2 D users in this two system models are deduced,such as outage probability,mean capacity and bit error rate.According to the theoretical data result of the D2 D communications analyzed by the closed-formexpression,increasing the interference temperature Q can improve the communication performance of the D2 D user,and changing the parameters of this two generalized distributions will produce different trends of its communication performance.Finally,this thesis compares the performance of two generalized distributed fading models,and the theoretical results can be used to guide the design and optimization of D2 D communication system over the actual fading channel model.