Stochastic power control with averaging

Abstract

Uplink communication in a cellular radio network is considered where the base station in each cell employs a linear or nonlinear (decision feedback) multiuser receiver. For any such receiver, the problem of minimizing total transmit power under the constraint that all the users of the network achieve their Qualityof-Service (QoS) objective in terms of signal-to-interference ratio (SIR) has been studied recently. Stochastic approximation based adaptive power control algorithms have been presented and analyzed both in the context of single user receivers and multiuser receivers. The primary focus of this paper is on improving the convergence properties of the standard stochastic approximation based power control strategy by using the more recent results on the stochastic approximation technique with averaging. Convergence issues of both the "non-averaged" and "averaged" algorithms are investigated and numerical examples are presented to demonstrate the performance improvement due to averaging.

Stochastic power control with bit estimation and base station processing

“…With this system model, we now review the decentralized stochastic power control algorithms proposed in [1] and [10] in brief.…”

“…It has been proved analytically in [1] that SPC converges asymptotically to the optimal power vector. It is well known that the optimal power is the solution of the deterministic power control algorithm Ô´Ò · ½ µ §À ½ Á´Ô´Òµµ (9) Á´Ô´Òµµ Ô´Òµ · ¾ Ù (10) as given in [6], which can be solved iteratively in a distributed system.…”

“…Also a brief review of the distributed stochastic power control algorithms of [1] and [10] is given. Throughout this paper it is assumed that each base station knows all of its users' gains with respect to itself, their respective delays and their spreading codes.…”

“…The optimal power is the solution to a deterministic power control problem where all the users transmit at their least possible power levels and also achieve their SIR requirement. As an extension to this algorithm, results on stochastic approximations with averaging [11,12] have been applied, and an improved rate of convergence along with an asymptotic convergence have been achieved for a constant step size [10].…”

“…The rest of the paper is organized as follows. In Section II a system model for an uplink CDMA system is developed and the algorithms of [1] and [10] are discussed in brief. Section III gives a detailed description of the proposed algorithms.…”