Joint Receiver and Transmitter Optimization for Energy-Efficient CDMA Communications

Abstract

Abstract-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 Paretooptimal. 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 noncooperative 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 closedform formulas based on large system analysis and the outcome of numerical experiments.

A Survey of Energy-Efficient Techniques for 5G Networks and Challenges Ahead

“…The throughput was the first metric to be considered in the context of energy efficiency, and its use dates back to the seminal works [11], [12], and [32], in the context of CDMA networks. These studies spurred the interest for energyefficient resource allocation in wireless networks, and a throughput-based definition of energy efficiency was used in [33]- [36] proposing game-theoretic approaches for energy-efficient multiple access networks, in [37] with reference to cognitive radio systems, in [38] in conjunction with widely linear receivers, in [39] for ultrawideband systems, and in [40] for relay-based systems. -Outage capacity.…”

Energy-Efficient Precoding for Multiple-Antenna Terminals

“…To the authors' knowledge, in all works using this approach ( [9], [4], [10], [11], [12], [13], etc. ), the same (pragmatic) choice is made for f : f (x) = (1−e −αx ) N , where α is a constant and N the block length in symbols.…”

Power and Spectral Efficient Multiuser Broadband Wireless Communication System

“…This channel state information (CSI) is exploited to design optimized system and several such algorithms for CDMA and MC-CDMA systems are reported in literature. The optimized systems include adaptive algorithm to minimize the total transmitted power (Lok & Wong;, signal-to-interference ratio (SIR) balanced optimum power control in CDMA (Wu;, joint optimization of spreading codes and a utility based power control (Reynolds & Wang;, joint rate and power control (Kim;, joint transmitter-receiver optimization using multiuser detection and resource allocation for energy efficiency in wireless CDMA networks (Buzzi & Poor;, using transmitter power control, receiver array processing and multiuser detection (Seo & Yang,2006) etc. The objective of the optimized methods, in general, is to minimize transmit power and maximize per user's data transmission rate.…”