Showing papers by "Stefan Parkvall published in 1995"

Sensitivity analysis of linear DS-CDMA detectors to propagation delay estimation errors

Abstract: An asynchronous direct-sequence code division multiple access (DS-CDMA) communication system operating over an additive white Gaussian noise (AWGN) channel is considered. In many applications, the near-far problem can be the limiting factor. Several near-far resistant receivers have therefore been proposed (e.g., the decorrelating receiver). These receivers assume perfect knowledge of the propagation delay from all users to the receiver. In practice, the delays are estimated and therefore subject to estimation errors. The performance penalty these errors impose on linear detectors, especially the decorrelating detector, is evaluated.

Parameter Estimation and Detection of DS-CDMA Signals subject to Multipath Propagation

Abstract: In this paper we consider the problem of estimating the propagation delays and relative amplitudes of the transmitted signals as well as detecting the data bits in an asynchronous direct-sequence code division multiple access (DS-CDMA) system operating over a fading channel. A subspace based estimator is proposed for estimating the propagation delays. The path gains and data bits are estimated with minimum mean squared error techniques. Special attention is paid to the near-far problem.

Propagation Delay Estimation of Fading DS-CDMA Signals

Abstract: In this paper we consider the problem of estimating the propagation delays of the transmitted signals in an asynchronous direct-sequence code division multiple access (DS-CDMA) system operating over a fading channel. Two estimators based on subspace techniques are compared and the Cram er-Rao Bound, a lower bound on the variance of any unbiased estimator, is derived. Special attention is paid to the near-far problem.