Secure Performance Of WCDMA And Joint Transmit-receive Diversity Over Fading Channels

The security of wireless communication system is mainly based on the physical layer upper level symmetric cryptography mechanism and the encryption algorithm of public key cryptography mechanism.Cracking the encryption algorithm requires extremely high computational complexity,thus ensuring the security of the encrypted data.As eavesdropper's computational capabilities increase,this type of security mechanism that relies on computational complexity is increasingly being challenged.On the other hand,due to the nature of wireless channel and the expansion of the network structure,the distribution and management of keys have encountered great difficulties.Based on this background,the physical layer security technology of wireless communication opens up a new solution of wireless communication for secure transmission.This technology exploits the physical characteristics of the wireless channel to achieve information theoretic transmission.Therefore,this paper studies the physical layer security of multiple input multiple output flat fading channels and frequency selective fading channel,respectively.Imperfect channel state information(CSI)and feedback delay will deteriorate the security of transmit antenna selection(TAS)/receiving maximum ratio combining(MRC)joint transmit and receive diversity wireless communication systems over flat fading channels.The minimum mean square error(MMSE)channel predictor is an effective maasure to mitigate the impact of imperfect CSI and delay.Firstly,the physical layer security performance of predictive transmit antenna selection(TASP)/MRC joint transmit and receive diversity wireless communication systems over Rayleigh block fading channels is investigated in this paper.Derives the exact closed-form expressions for the non-zero secrecy capacity probability,secrecy outage probability and asymptotic secrecy outage probability of TASP/MRC joint transmit and receive diversity over Rayleigh block fading channels in the presence of single or multi-eavesdroppers,and numerical and simulation results are presented.The results show that increasing the number of the legitimate receiver antennas is helpful to improve the effect of the feedback delay on the security performance of the TASP/MRC diversity,increase the number of eavesdropper receivers or the number of antennas will deteriorate the security performance of the TASP/MRC diversity,the security diversity gain of TASP/MRC diversity is the number of legitimate receiver antennas,which is independent of the number of eavesdroppers,the number of antennas.The wideband code division multiple access(WCDMA)systems is one of the three standards of third-generation mobile communication systems,which employs transmit space-time block codes(STBC)/receive two-dimension RAKE(2D-RAKE)receivers joint transmit and receive diversity,and the research on the physical layer security of WCDMA should be concerned.Therefore,the physical layer security performance of WCDMA systems with STBC and 2D-RAKE receivers over frequency selective correlated Nakagami fading is investigated in this paper.Derives the exact closed-form expressions for the non-zero secrecy capacity probability,secrecy outage probability and asymptotic secrecy outage probability of WCDMA systems with STBC and 2D-RAKE receivers over frequency selective correlated Nakagami fading channel in the presence of single or multi-eavesdroppers,and numerical and simulation results are presented.The results show that the greater the Nakagami fading parameters of the main channel is,the better security performance of the WCDMA system is,increase the correlation coefficient of the legitimate receiver antenna will deteriorate the security performance of the WCDMA systems,the secrecy diversity order of WCDMA systems is the sum of diversity order of each separable path on the main channel,which is independent of the number of eavesdroppers,the number of antennas.