Security Performance Of Multi-users Channel Based On Information Theoretic

The broadcast nature of wireless channels poses both benefits and penalties for secure communication. The cooperation between nodes can improve the communication efficiency. However, the messages that transmitted by the untrusted nodes are particularly vulnerable to eavesdropping or interference, which makes it difficult to be guaranteed for the security of wireless networks communication. Unlike the traditional cryptography, in this paper, we study the security performance of multi-users channel from information theoretic viewpoint which is measured by the residual ambiguity about the transmitted message at the eavesdropper called the equivocation rate.This paper focuses on the multi-users channels in wireless networks based on the information theory security. The multiple-level relay-eavesdropper channel is proposed, the equivocation rate and the achievable secrecy rate are derived in discrete memoryless channel, and the decoding strategy is improved. Then the corresponding results of two-level relay-eavesdropper channel and one relay-eavesdropper channel are derived in gaussian channel, and are compared by simulation under the limited power. The results show that multi-level relays can be deployed to improve the secrecy rate when the single relay node is far away from the source node.In practical communication system, it is difficult to design the relay so that it can transmit and receive at the same time in the same frequency band. The orthogonal relay-eavesdropper channel is proposed base on parallel relay-eavesdropper channel. Under the total frequency band, the optimal resource allocation strategy is discussed in detail. The simulation results that the secrecy rate with optimal resource allocation is higher than that with equal resource allocation, which makes the security performance improved greatly.