Strong secrecy communication over a discrete memoryless state-dependent multiple access channel (SD-MAC) with an external eavesdropper is investigated. The channel is governed by discrete memoryless and i.i.d. channel states and the channel state information (CSI) is revealed to the encoders in a causal manner. An inner bound of the capacity is provided. To establish the inner bound, we investigate coding schemes incorporating wiretap coding and secret key agreement between the sender and the legitimate receiver. Two kinds of block Markov coding schemes are studied. The first one uses backward decoding and Wyner-Ziv coding and the secret key is constructed from a lossy reproduction of the CSI. The other one is an extended version of the existing coding scheme for point-to-point wiretap channels with causal CSI. We further investigate some capacity-achieving cases for state-dependent multiple access wiretap channels (SD-MAWCs) with degraded message sets. It turns out that the two coding schemes are both optimal in these cases.

翻译：本文研究了存在外部窃听者时，离散无记忆状态依赖多址接入信道上的强保密通信。该信道受离散无记忆且独立同分布的信道状态控制，且信道状态信息以因果方式提供给编码器。本文给出了容量的一个内界。为建立该内界，我们研究了结合窃听编码和发送方与合法接收方之间密钥协商的编码方案。研究了两种块马尔可夫编码方案。第一种采用后向解码和Wyner-Ziv编码，密钥由信道状态信息的有损重构构造而成。第二种是现有带因果信道状态信息的点对点窃听信道编码方案的扩展版本。我们进一步研究了具有退化消息集的状态依赖多址接入窃听信道的一些容量可达情况。结果表明，这两种编码方案在这些情况下均达到最优。