关键词: 信道状态信息, 多径信道, 物理层, 安全容量, 预编码, 单载波频域均衡, 窃听

Abstract:

In the multipath channel scenario of passive eavesdropping， the EaVEsdropper （Eve） only performs passive eavesdropping without transmitting any radio signals. The transmitter （Alice） is unable to determine any information of Eve， which brings great challenges to the secure transmission of information. In order to guarantee the secure transmission of information， under the condition that Alice knew the Channel State Information （CSI） of the legitimate receiver （Bob） but not Eve’s CSI， a precoding scheme to guarantee the physical layer security of legitimate Bob was proposed， and the security performance of the system was improved by enhancing the quality of the received signals of Bob. Firstly， without considering Eve， the precoding scheme for the upper bound on the reachable channel capacity of Bob was given based on the known CSI of Bob. Stable security capacity was obtained by using the channel specificity between Alice-Bob and Alice-Eve links. Then， the accurate closed-form expression for Bob’s average Bit Error Rate （BER） was derived from Bob’s outage probability in a Rayleigh flat fading environment. Simulation experimental results show that the proposed scheme can ensure Bob’s channel capacity always better than Eve’s channel capacity without changing the complexity of the receiver. At the same time， the proposed scheme can effectively improve the BER performance of Bob under the condition that the BER performance of Eve is greatly suppressed. And the security capacity is always guaranteed even when the Eve’s location condition is better than that of Bob.

Key words: Channel State Information (CSI), multipath channel, physical layer, security capacity, precoding, Single Carrier-Frequency Domain Equalization (SC-FDE), eavesdropping