Multi-rate detection for the IS-95 CDMA forward traffic channels

Author

Cohen, Edith ; Lou, Hui-Ling

Author_Institution

AT&T Bell Labs., Murray Hill, NJ, USA

Volume

3

fYear

1995

fDate

14-16 Nov 1995

Firstpage

1789

Abstract

The IS-95 direct sequence code division multiple access (DS-CDMA) system has become a US digital cellular standard. In the forward traffic channels (from the base station to the mobiles), the speech encoder rate can vary, depending on the speech activity in the transmitter. At the receiver, the decoder does not know which one of the speech encoder rate the transmitter used. This paper focuses on the IS-95 system that uses the 8 kbps speech encoder and describes an algorithm to determine the encoder rate used for the transmitted sequence, with high confidence, so that the appropriate Viterbi decoder can be applied only once and not four times. This can reduce the overall decoder complexity and increase the throughput by a factor of two. It can also reduce the power consumption in the decoder

Keywords

Gaussian channels; Rayleigh channels; Viterbi decoding; Viterbi detection; cellular radio; code division multiple access; digital radio; fading; pseudonoise codes; speech coding; spread spectrum communication; telecommunication standards; 8 kbit/s; DS-CDMA system; Gaussian channels; IS-95 CDMA forward traffic channels; IS-95 standard; IS-95 system; Rayleigh channels; US digital cellular standard; Viterbi decoder; algorithm; base station; decoder complexity reduction; direct sequence code division multiple access; fading; multirate detection; performance evaluation; power consumption reduction; receiver; speech activity; speech encoder rate; throughput; transmitted sequence; transmitter; Base stations; Code standards; Decoding; Direct-sequence code-division multiple access; Energy consumption; Multiaccess communication; Speech; Throughput; Transmitters; Viterbi algorithm;

fLanguage

English

Publisher

ieee

Conference_Titel

Global Telecommunications Conference, 1995. GLOBECOM '95., IEEE

Print_ISBN

0-7803-2509-5

Type

conf

DOI

10.1109/GLOCOM.1995.502715

Filename

502715