| In this thesis, reliability, rate and security in a general cooperative, multiple antenna, multi-terminal network is considered. Reliability and rate are measured in terms of the diversity-multiplexing tradeoff (DMT). Several subcases of this most general network are examined taking into account the processing capability of the relays (half-duplex or full-duplex), and the network geometry (clustered or non-clustered). Firstly, the multiple antenna relay channel is studied to understand the effect of increased degrees of freedom in the direct link on reliability and rate. For this network, DMT upper bounds are found and the achievable performance of decode-and-forward (DF), and compress-and-forward (CF) protocols are investigated. It is shown that these two protocols have significant differences, and that the half-duplex DMT behavior can significantly be different from the full-duplex case. In addition to the multiple-access relay channel (MARC), a system with a single source-destination pair and multiple relays, each node with a single antenna is investigated. For the latter it is shown that even under the idealistic assumption of full-duplex relays and a clustered network, this virtual multi-input multi-output (MIMO) system can never fully mimic a real MIMO.;Next, to explore security issues a four terminal network with a single source-destination pair, a relay and a wire-tapper is studied for two different cases. In the first case the relay assists the source-destination communication, whereas in the second the relay assists the wire-tapper. For the former, upper and lower bounds on the capacity-equivocation rate region are established for a degraded wire-tapper for both discrete memoryless and Gaussian cases. It is observed that in the presence of a wiretapper, some conventional beliefs about cooperation may no longer be true. For the latter, different relaying protocols are compared in terms of achievable secrecy rates. It is shown that comparison of relaying protocols and best power allocation schemes, when the relay assists the source-destination communication, do not readily extend to the case when the relay assists the wire-tapper. |
