Secure MIMO communication system based on time varying linear transformation

Based on time varying linear transformation (TVLT), a novel encrypting mechanism for multi-input multi-output (MIMO) communication system is proposed in this paper. Without exhaustive checks through computer search for the proper spacetime codes, a coded MIMO system can simply achieve full diversity through TVLT. Combined with the LDPC code, TVLT also provides the full diversity gain and higher coding gain at the same time for MIMO system. Further, utilizing the special property of TVLT, we put forward and discuss a new encrypting mechanism consequently. The principle of the new secure system is studied carefully, and corresponding encrypting/decrypting algorithms are given in detail. Compared with the common encrypting methods for MIMO system, the new mechanism accomplishes both TVLT and encrypting process for space-time codewords together, it almost has no effect on the transmit data rate. The simulation results also verified the validity and performance of the new encrypting method.