Research On Physical Layer Security In Relay Cooperation Based On MMSE

Due to the advantages like mobility and convenience,wireless communication is paid more and more attention recently.However,wireless channel transmit information via electromagnetic wave which is easy to be influenced by noise and weather factor.Thus,the security of wireless communication is significant to focus on.Research nowadays major study the security of the network layer and the above,which is based on error-free transmission in physical layer.But in physical layer,transmitter broadcasts information to all the receivers,which is possible to be wiretapped by eavesdroppers.Therefore it's important to enhance the security performance and to prevent wiretap in physical layer.People are used to using secrecy capacity as the index to measure the performance of physical layer security,but when there exist multi users in the communication system,the calculation and the complexity would be large if we using secrecy capacity as the measurement.This paper would adopt minimum mean square error as the index to measure the performance of physical layer.Do estimation of the received signal and calculate the MMSE with the original transmitted signal,then taking the value of the error show the difference between the received signal and the transmitted signal.And the MMSE could reflect the degree of the signal affected by the nosie in the channel.The calculation and the procession of MMSE is easy so that this method is on advantages.This paper study the MIMOME communication system with relay nodes,and do the linear precoder matrix design in source and relay respectively,while the MMSE is the measurement to show the performance of the system.Through limiting the error in eavesdropper and the whole power,we calculate the MMSE of the system and obtain the optimal precoder matrix,to make the system reach a safer situation.This paper discuss the several kinds of communication system,depending on the number of the receiving routes.And we also focus on the case of the imperfect channel state information and compare the performance of varies of algorithms in the simulation results.