Cooperative Precoding/Resource Allocation Games under Spectral Mask and Total Power Constraints

The use of orthogonal signaling schemes such as time-, frequ ency-, or code-division multiplexing (T-, F-, CDM) in multi-user systems allows for power-efficie nt simple receivers. It is shown in this paper that by using orthogonal signaling on frequency selective f ading channels, the cooperative Nash bargaining (NB)-based precoding games for multi-user systems , which aim at maximizing the information rates of all users, are simplified to the corresponding coope rativ resource allocation games. The latter provides additional practically desired simplifications t o transmitter design and significantly reduces the overhead during user cooperation. The complexity of the cor responding precoding/resource allocation games, however, depends on the constraints imposed on the us ers. If only spectral mask constraints are present, the corresponding cooperative NB problem can b e formulated as a convex optimization problem and solved efficiently in a distributed manner using dual decomposition based algorithm. However, the NB problem is non-convex if total power constra in s are also imposed on the users. In this case, the complexity associate with finding the NB sol uti n is unacceptably high. Therefore, the multi-user systems are categorized into bandwidthand pow er-dominant based on a bottleneck resource, and different manners of cooperation are developed for each type of systems for the case of two-users. Such classification guarantees that the solution obtained i ach case is Pareto-optimal and actually can be identical to the optimal solution, while the complexity i s significantly reduced. Simulation results demonstrate the efficiency of the proposed cooperative prec oding/resource allocation strategies and the reduced complexity of the proposed algorithms.