Comments on Broadcast Channels-英文文献.pdf

2524 IEEE TRANSACTIONS ON INFORMATION THEORY, VOL. 44, NO. 6, OCTOBER 1998 Comments on Broadcast Channels Thomas M. Cover, Fellow, IEEE (Invited Paper) Abstract— The key ideas in the theory of broadcast channels are illustrated by discussing some of the progress toward finding the capacity region. The capacity region is still unknown. Index Terms— Binning, broadcast channel, capacity, degraded Fig. 1. Broadcast channel. broadcast channel, feedback capacity, Slepian–Wolf, superposi- tion. Definition: The capacity region of the broadcast channel is the closure of the set of achievable rates. I. INTRODUCTION It is often the case in practice that one received signal is broadcast channel has one sender and many receivers. a degraded, or corrupted, version of the other. One receiver AThe object is to broadcast information to the receivers. may be farther away or “downstream.” When forms The information may be independent or nested. We shall treat a Markov chain, i.e., when broadcast channels with two receivers as shown in Fig. 1. we say that is a physically degraded version of and Multiple receiver broadcast channels are defined similarly. that is a physically degraded broadcast channel. Definit