  A unified approach to energy-efficient power control is proposed for
code-division multiple access (CDMA) networks. The approach is applicable to a
large family of multiuser receivers including the matched filter, the
decorrelator, the linear minimum mean-square error (MMSE) receiver, and the
(nonlinear) optimal detectors. It exploits the linear relationship that has
been shown to exist between the transmit power and the output
signal-to-interference-plus-noise ratio (SIR) in the large-system limit. It is
shown that, for this family of receivers, when users seek to selfishly maximize
their own energy efficiency, the Nash equilibrium is SIR-balanced. In addition,
a unified power control (UPC) algorithm for reaching the Nash equilibrium is
proposed. The algorithm adjusts the user's transmit powers by iteratively
computing the large-system multiuser efficiency, which is independent of
instantaneous spreading sequences. The convergence of the algorithm is proved
for the matched filter, the decorrelator, and the MMSE receiver, and is
demonstrated by means of simulation for an optimal detector. Moreover, the
performance of the algorithm in finite-size systems is studied and compared
with that of a conventional power control scheme, in which user powers depend
on the instantaneous spreading sequences.
