  This paper focuses on the cross-layer issue of joint multiuser detection and
resource allocation for energy efficiency in wireless CDMA networks. In
particular, assuming that a linear multiuser detector is adopted in the uplink
receiver, the case considered is that in which each terminal is allowed to vary
its transmit power, spreading code, and uplink receiver in order to maximize
its own utility, which is defined as the ratio of data throughput to transmit
power. Resorting to a game-theoretic formulation, a non-cooperative game for
utility maximization is formulated, and it is proved that a unique Nash
equilibrium exists, which, under certain conditions, is also Pareto-optimal.
Theoretical results concerning the relationship between the problems of SINR
maximization and MSE minimization are given, and, resorting to the tools of
large system analysis, a new distributed power control algorithm is
implemented, based on very little prior information about the user of interest.
The utility profile achieved by the active users in a large CDMA system is also
computed, and, moreover, the centralized socially optimum solution is analyzed.
Considerations on the extension of the proposed framework to a multi-cell
scenario are also briefly detailed. Simulation results confirm that the
proposed non-cooperative game largely outperforms competing alternatives, and
that it exhibits a quite small performance loss with respect to the socially
optimum solution, and only in the case in which the users number exceeds the
processing gain. Finally, results also show an excellent agreement between the
theoretical closed-form formulas based on large system analysis and the outcome
of numerical experiments.
