Decentralized dynamic power control for cellular CDMA systems

Abstract

The control of transmit power has been recognized as an essential requirement in the design of cellular code-division multiple-access (CDMA) systems. Indeed, power control allows for mobile users to share radio resources equitably and efficiently in a multicell environment. Much of the work on power control for CDMA systems found in the literature assumes a quasi-static channel model, i.e., the channel gains of the users are assumed to be constant over a sufficiently long period of time for the control algorithm to converge. In this paper, the design of dynamic power control algorithms for CDMA systems is considered without the quasi-static channel restriction. The design problem is posed as a tradeoff between the desire for users to maximize their individual quality of service and the need to minimize interference to other users. The dynamic nature of the wireless channel for mobile users is incorporated in the problem definition. Based on a cost minimization framework, an optimal multiuser solution is derived. The multiuser solution is shown to decouple, and effectively converge, to a single-user solution in the large system asymptote, where the number of users and the spreading factor both go to infinity with their ratio kept constant. In a numerical study, the performance of a simple threshold policy is shown to be near that of the optimal single-user policy. This offers support to the threshold decision rules that are employed in current cellular CDMA systems.

Fractional power control for decentralized wireless networks

“…The Foschini-Miljanic algorithm is an iterative, distributed power control method that performs this task assuming that each receiver tracks its instantaneous SINR and feeds back power adjustments to its transmitter [3]. Considerable work has deeply explored the properties of these algorithms, including developing a framework that describes all power control problems of this type [4], as well as studying the feasibility and implementation of such algorithms [5], [6], including with varying channels [7]; see the recent monographs [8] [9] for excellent surveys of the vast body of literature. This body of work, while in many respects quite general, has been primarily focused on the cellular wireless communications architecture, particularly in which all users have a common receiver (i.e., the uplink).…”

Power Control, Capacity, and Duality of Uplink and Downlink in Cellular CDMA Systems

“…The recent work of [2] employs a discrete-time Markov chain to model time-variant channel gain. Dynamic multiuser power control is formulated in the framework of Markov decision processes with an objective function trading off between a minimal total received power and certain functionals of transmission quality.…”

Development an Elevator Emergency Call Transmission System

“…The received signal sounds buzzer through SPI communication and SMS is processed. Through RS232 communication, the SMS is sent to CDMA [8][9][10], and then it is finally received. Ultimately, EECTS is operated via direct call equipment.…”