The two-user broadcast channel (BC) with receivers connected by cooperative links of given capacities, known as conferencing decoders, is considered. A novel outer bound on the capacity region is established. This outer bound is derived using multiple applications of the Csisz\'{a}r-K\"{o}rner identity. New achievable rate regions are also presented. A first achievable rate region is derived by applying Marton's coding as the transmission scheme, and quantize-bin-and-forward at one receiver first and then a combination of decode-and-forward and quantize-bin-and-forward at the other receiver as cooperative strategy. A second achievable rate region is given by applying a combination of decode-and-forward and quantize-bin-and-forward at one receiver first and then quantize-bin-and-forward at the other receiver. It is proved that the outer bound coincides with the first achievable rate region for a class of semi-deterministic BCs with degraded message sets. This is the first capacity result for the two-user BC with bidirectional conferencing decoders. A capacity result is also derived for a new class of more capable semi-deterministic BCs with both common and private messages and one-sided conferencing. For the Gaussian BC with conferencing decoders, if the noises at the decoders are fully correlated (i.e., the correlation is either 1 or -1), the new outer bound yields exact capacity region for two cases: i) BC with degraded message sets; ii) BC with one-sided conferencing from the weaker receiver to the stronger receiver. An interesting consequence of these results is that for a Gaussian BC with fully negatively correlated noises and conferencing decoders of fixed cooperation link capacities, it is possible to achieve a positive rate bounded away from zero using only infinitesimal amount of transmit power.

翻译：本文研究了一种具有双向会议解码器的两用户广播信道（BC），其中接收机通过给定容量的协作链路（即会议解码器）相连。我们建立了一个新颖的容量区域外边界。该外边界是通过多次应用Csiszár-Körner恒等式推导得出的。同时，本文也提出了新的可达速率区域。第一个可达速率区域是通过采用Marton编码作为传输方案，并在一接收机处先采用量化-装箱-转发，然后在另一接收机处结合解码-转发与量化-装箱-转发作为协作策略而推导得到的。第二个可达速率区域则是通过在一接收机处先结合解码-转发与量化-装箱-转发，然后在另一接收机处采用量化-装箱-转发而给出的。我们证明了，对于一类具有退化消息集的半确定性广播信道，该外边界与第一个可达速率区域重合。这是关于具有双向会议解码器的两用户广播信道的首个容量结果。同时，针对一类新的、具有更强能力的、包含公共消息和私有消息且具有单向会议的半确定性广播信道，我们也推导出了一个容量结果。对于具有会议解码器的高斯广播信道，若解码器处的噪声完全相关（即相关系数为1或-1），则新的外边界在两种情况下给出了精确的容量区域：i) 具有退化消息集的广播信道；ii) 具有从弱接收机到强接收机的单向会议的广播信道。这些结果的一个有趣推论是：对于具有完全负相关噪声和固定协作链路容量的会议解码器的高斯广播信道，仅使用无穷小的发射功率即可实现一个远离零的正速率。