The relay channel with unreliable helper is introduced and studied. The model is that of a classical relay channel where the input from the relay to the channel has an extra primitive link whose presence is not assured a priori. The extra link represents a helper who may decide not to cooperate in transmission. The goal is to devise robust coding schemes that exploit all the relay links when they are present, but can also operate, possibly at reduced rates, when the extra primitive link (helper) is absent. The capacity region of this class of problems is defined, and fully characterized for degraded relay channels. The degraded Gaussian relay channel with unreliable relay link is solved.

翻译：本文引入并研究了不可信中继辅助的协作信道模型。该模型为经典中继信道，其中中继到信道的输入存在一条额外的基元链路，该链路的存在并非先验确定。该额外链路代表一个可能决定不参与传输的中继辅助节点。研究目标在于设计鲁棒的编码方案，使得当所有中继链路存在时能充分利用这些链路，而当额外基元链路（中继辅助节点）缺失时，系统仍能以（可能降低的）速率正常工作。本文定义了该类问题的容量区域，并完整刻画了退化中继信道的容量特征，同时解决了退化高斯中继信道在不可信中继链路场景下的容量问题。