The multiple access channel (MAC) capacity with feedback is considered under feedback models designed to tease out which factors contribute to the MAC feedback capacity benefit. Comparing the capacity of a MAC with ``perfect'' feedback, which causally delivers to the transmitters the true channel output, to that of a MAC with ``independent'' feedback, which causally delivers to the transmitters an independent instance of that same channel output, allows separation of effects like cooperation from alternative feedback benefits such as knowledge of the channel instance. Proving that the Cover-Leung (CL) achievability bound, which is known to be loose for some channels, is achievable also under (shared or distinct) independent feedback at the transmitters shows that the CL bound does not require transmitter knowledge of the channel instance. Proving that each transmitter's maximal rate under independent feedback exceeds that under perfect feedback highlights the potential power of an independent look at the channel output.

翻译：考虑在多址信道（MAC）反馈容量研究中，设计不同反馈模型以区分影响反馈增益的要素。通过对比“完美”反馈（将真实信道输出因果地传递给发送端）与“独立”反馈（将同一信道输出的独立实例因果地传递给发送端）下的MAC容量，可以分离合作效应与信道实例知识等替代反馈增益。证明Cover-Leung（CL）可达界（已知在某些信道下是非紧的）在发送端共享或独立独立反馈下仍可实现，表明CL界无需发送端知晓信道实例。证明独立反馈下各发送端的最大速率高于完美反馈下的对应值，凸显了发送端独立观测信道输出的潜在优势。