Date Added: Mar 2010
The authors investigate the problem of multi-user radio resource allocation for Orthogonal Frequency Division Multiple Access (OFDMA) Amplify-and-Forward (AF) relays. In the single-user case, the problem reduces to the well know assignment problem, which maximizes the user rate. For the multi-user case they devise a resource allocation algorithm to achieve max-min fairness. They find max-min fairness since it can provide almost flat ubiquitous coverage. They start by formulating a convex optimization, which takes a parameter that asymptotically makes the optimization produce max-min fair rates. Since the optimization is a convex problem, they are able to devise a suboptimal gradient-based algorithm to solve it quickly. Simulations show that the algorithm achieves results very close to the optimum solutions due to its gradient origins.