Research On The Security Degree Of Freedom Of MIMO X Interference Network With Confidential Message

Multi input and multi output(MIMO)technology,by which the capacity and transmission distance of the system can be increased without increasing the transmission bandwidth or the total transmission power,utilizes multiple antennas on the transmitter to send signals independently and utilizes multiple antennas on the receiver to receive and recover signals.Interference alignment is not only a new network interference management technology,but also a physical layer technology that can realize information security transmission.When the interference alignment technology is applied to MIMO interference network,the received signal can be limited in the same subspace of the undesired receiver,and the desired signal of each receiver can be retrieved by the decoding matrix orthogonal to the interference direction,thereby higher system freedom and safety freedom can be obtained.In this paper,based on the multi-antenna technology and aiming at improving the security freedom of the system,the security freedom of the joint artificial noise and interference alignment scheme is studied for the MIMO X interference network with confidential information.The main study contents are summarized as follows:(1)The SDoF of the MIMO X network combining artificial noise and interference alignment technology:Firstly,an AN-IA scheme combining artificial noise with interference alignment is proposed for the M×2 user MISO X-network with confidential information configured with symmetrical antenna,in which the transmitter is equipped with A(number)antennas,and the receiver is equipped with a single antenna.The scheme takes one of the transmitter as an auxiliary node to send only the artificial noise and makes the other transmitters send confidential information,then the transmission of confidential information can be realized by aligning the interference signal and artificial noise to the interference signal space of the receiver.The SDo F analysis shows that the SDo F of the system achieved by implementing AN-IA scheme in the M×2 user MISO X network with confidential information is 2A(M-1)/(A(M-1)+1).Then,the achievable SDo F of M×K users MISO X network with confidential information configured with symmetric antenna is studied.To facilitate the analysis,the M×K user MISO X network with confidential information is considered equivalent to K user M×1 broadcast channel with confidential information,and a blind IA-AN scheme combining interference alignment with artificial noise is proposed.The interference alignment using the antenna switch mode to realize channel coherent structure without prediction of CSIT;Each transmitter sends both confidential information and artificial noise.The SDo F analysis shows that,based on the specific number of antennas and the number of users,the achievable SDo F of M×K user MISO X network with confidential information is KA(M-1)/(K+MA-1).(2)The interference alignment scheme and SDo F are studied for the M×N user MISO XNCM network with multi-node and multi-antenna configuration.Firstly,a interference alignment scheme combining artificial noise with space-time(AN-STIA)is proposed and the achievable SDo F of the system under the condition of appropriately delayed CSIT is studied for the M×N user MISO XNCM network.By designing the precoding matrix of the transmitter,the trade-offs domain of achievable SDo F under CSI feedback delay of the transmitter with multiple antennas is given and the achievable SDo F of the channel obtained in different schemes are compared and analyzed.The result shows that a higher trade-offs domain of achievable SDo F can be achieved under the AN-STIA scheme on the basis of the actual appropriate delayed CSIT than that under the ideal CSIT.The achievable SDo F of M×N user MIMO X network system with confidential information is further discussed.It is found by comparing the SDo F obtained through different schemes that a higher SDo F can be achieved under AN-STIA scheme when the transmitter node is provided with enough antennas,comparing with the space-time interference alignment scheme without CSIT feedback delay and output asymmetric CSIT feedback delay.