Proc. IEEE Int. Conf. on Acoustics, Speech, and Signal Processing, vol. 5, pp. 2869-2873, June 2000.

Self-Recovering RAKE Receiver for Asynchronous CDMA Systems

Murat Torlak (1) and Brian L. Evans (2)

(1) Department of Electrical and Computer Engineering, ECS 33, The University of Texas at Dallas, Richardson, TX 75083
torlak@utdallas.edu

(2) Department of Electrical and Computer Engineering, Engineering Science Building, The University of Texas at Austin, Austin, TX 78712-1084
bevans@ece.utexas.edu

Paper - Poster

Abstract

In asynchronous code division multiple access systems, transmission over frequency-selective channels subjects the signal to interchip interference and intersymbol interference, both of which cause multiple access interference. The multiple access interference cannot be easily eliminated without the knowledge of the channel parameters. Both blind adaptive and subspace-based multiuser receivers have been proposed to eliminate the interference. In this paper, we propose a self-recovering RAKE receiver that does not require training sequences or knowledge of interfering user signature waveforms. The contribution of this paper is the combination of constant modulus algorithm and previously derived constraints. The constraints depend on the multipath structure of the desired signal. The proposed receiver converges faster than the blind adaptive multiuser receivers. Its fast convergence and low complexity make it well suited for rapidly time-varying mobile radio frequency selective fading channels. By simulation, we compare the proposed method with blind adaptive constrained LMS RAKE receiver and minimum output energy receiver.

Last Updated 11/24/00.