Asynchronous near-far resistant DS-CDMA receivers without a priori synchronization

Author

Parkvall, Stefan ; Ström, Erik G. ; Milstein, Laurence B. ; Ottersten, Bjorn E.

Author_Institution

Center for Wireless Commun., California Univ., San Diego, La Jolla, CA, USA

Volume

47

Issue

1

fYear

1999

fDate

1/1/1999 12:00:00 AM

Firstpage

78

Lastpage

88

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

Keywords

Viterbi decoding; code division multiple access; delay estimation; demodulation; error correction codes; feedback; interference suppression; land mobile radio; multiuser channels; radio receivers; radiofrequency interference; spread spectrum communication; DS-CDMA; Viterbi decoding; asynchronous near-far resistant receivers; data demodulation; decision feedback technique; error correcting coding; filter design; interference suppression; minimum mean square error criterion; mobile radio; near-far problem; propagation delay estimation; propagation delays; subspace-based technique; trellis; two-state Viterbi algorithm; Delay estimation; Demodulation; Direct-sequence code-division multiple access; Feedback; Filters; Interference suppression; Mean square error methods; Multiaccess communication; Propagation delay; Viterbi algorithm;

fLanguage

English

Journal_Title

Communications, IEEE Transactions on

Publisher

ieee

ISSN

0090-6778

Type

jour

DOI

10.1109/26.747815

Filename

747815