Resource Allocation and Interference Mitigation in Cooperative Networks

Varying channel conditions and interference are inherent in wireless communication systems and can severely degrade communication rates. Cooperation via relaying, on the other hand, is a well-known technique primarily used to provide significant rate improvements to point-to-point communications. In this dissertation, the impact of the resource allocation in cooperative networks with multiple relays and cooperation in interference-prone networks are investigated.;To model and explore the resource allocation in cooperative networks, we first study the parallel half-duplex relay channel with single relay and then extend our analysis to parallel relay channel with multiple relays. For the decode-and-forward protocol, optimization problems for joint power, time and subchannel allocation under per-node power constraints are formulated to maximize the total transmission rate between the source and the destination. To solve this optimization problem, first the optimal power allocation for a given subchannel allocation is found. Then a greedy algorithm that jointly allocates subchannels and power is described. The limiting case where the number of subchannels goes to infinity is also studied.;Next, we focus on the interference mitigation problem in two cooperative networks: a relay channel with orthogonal components and structured interference non-causally available only at the source and half-duplex Gaussian diamond relay channel with structured interference known only at one relay. The interference signal has structure in that it is produced by another transmitter communicating with its own destination. Moreover, the interferer is not willing to adjust its communication strategy to minimize the interference. Knowledge of the interferer's signal may be acquired by some terminals by exploiting HARQ retransmissions on the interferer's link. For the former setting, the source can then utilize the relay not only for communicating its own message, but also for cooperative interference mitigation at the destination by informing the relay about the interference signal. Proposed transmission strategies are based on partial decode-and-forward (PDF) relaying and leverage the interference structure. Achievable schemes are derived for discrete memoryless models, Gaussian and Ricean fading channels. Furthermore, optimal strategies are identified in some special cases. For the Gaussian diamond relay channel setting, using structure of the interference, bounds for the Gaussian half-duplex diamond relay channel based on two transmission time patterns are established. The importance of exploiting the interference structure and transmission time patterns are discussed.