Cooperative strategies and capacity theorems for relay networks-英文文献.pdf

IEEE TRANSACTIONS ON INFORMATION THEORY, VOL. 51, NO. 9, SEPTEMBER 2005 3037 Cooperative Strategies and Capacity Theorems for Relay Networks Gerhard Kramer, Member, IEEE, Michael Gastpar, Member, IEEE, and Piyush Gupta, Member, IEEE Abstract— Coding strategies that exploit node cooperation are El Gamal, who developed two fundamental coding strategies developed for relay networks. Two basic schemes are studied: the for one relay [4, Theorems 1 and 6]. A combination of these relays decode-and-forward the source message to the destination, strategies [4, Theorem 7] achieves capacity for several classes or they compress-and-forward their channel outputs to the desti- nation. The decode-and-forward scheme is a variant of multihop- of channels, as discussed in [4]–[10]. Capacity-achieving codes ping, but in addition to having the relays successively decode the appeared in [11] for deterministic relay channels, and in [12], message, the transmitters cooperate and each receiver uses several [13] for permuting relay channels with states or memory. We or all of its past channel output blocks to decode. For the compress- will consider only random coding and concentrate on general- and-forward scheme, the relays take advantage of the statistical izing the two basic strategies of [4]. dependence between their channel outputs and the destination’s channel output. The strategies are applied to wireless channels, and A. Decode-and-Forward it is shown that decode-and-forward achieves the ergodic capacity with phase fading if phase information is available only locally, and The first strategy achieves the rates in [4, Theorem