Resolvability and Strong Secrecy for the Multiple Access Channel with Cooperation
We study secret communication over the discrete memoryless multiple-access channel with the following cooperation strategies: (i) degraded message sets, (ii) a common message, (iii) conferencing, (iv) cribbing, (v) feedback, and (vi) generalized feedback. For developing strong secrecy results, we utilize the methods and techniques of channel resolvability, which involves the characterization of the amount of randomness required at the inputs of the channel to approximately produce a chosen i.i.d. output distribution. For the multiple-access with degraded message sets, a common message, conferencing and feedback, we exactly characterize the channel resolvability region. For the multiple access channel with cribbing, we exactly characterize the channel resolvability region for the causal cribbing and non-causal cribbing scenarios. For the strictly-causal cribbing scenario, inner and outer bounds are provided. For the multiple-access channel with generalized feedback, we provide two inner bounds representing the role of decoding and randomness extraction, which can also be combined. Finally, leveraging the resolvability results, we derive achievable strong secrecy rate regions for each of the cooperation scenarios.