Showing papers by "Stefan Parkvall published in 1999"
TL;DR: An algorithm for time delay estimation in an asynchronous direct-sequence code-division multiple access (DS-CDMA) system which exploits the structure of the system better than previously known algorithms, is presented.
Abstract: The problem of near-far resistant time-delay estimation in an asynchronous direct-sequence code-division multiple-access system is considered, and by better exploiting the structure of the problem, estimators superior to previously known techniques are obtained. For a typical numerical example, a gain in signal-to-noise ratio of approximately 3 dB is obtained.
55 citations
TL;DR: Several receivers for data demodulation in an asynchronous direct-sequence code-division multiple access (DS-CDMA) system operating without prior knowledge of the propagation delays are proposed and compared and numerically shown to be near-far resistant.
Abstract: Several receivers for data demodulation in an asynchronous direct-sequence code-division multiple access (DS-CDMA) system operating without prior knowledge of the propagation delays are proposed and compared. Special attention is paid to the near-far problem, and the proposed schemes are numerically shown to be near-far resistant. The near-far resistance is obtained by estimating the a priori unknown propagation delay using a subspace-based technique. Quantities obtained in the estimation procedure are used to design a filter used for suppression of interference, according to the minimum mean square error criterion. Either a decision feedback technique or a simple two-state Viterbi algorithm is subsequently used for the data demodulation in the uncoded case. By extending the trellis used in the Viterbi algorithm, error correcting coding is easily implemented.
23 citations