Improved Viterbi decoder metrics for two-stage detectors in DS-CDMA
- Resource Type
- Periodical
- Authors
- Elezabi, A.; Duel-Hallen, A.
- Source
- IEEE Transactions on Wireless Communications IEEE Trans. Wireless Commun. Wireless Communications, IEEE Transactions on. 3(5):1399-1404 Sep, 2004
- Subject
- Communication, Networking and Broadcast Technologies
Computing and Processing
Signal Processing and Analysis
Viterbi algorithm
Detectors
Multiaccess communication
Maximum likelihood decoding
Multiple access interference
Iterative decoding
Interference cancellation
Convolutional codes
Performance gain
Multiuser detection
- Language
- ISSN
- 1536-1276
1558-2248
Modified branch metrics are proposed for single-user Viterbi decoders in two-stage detectors for convolutionally-encoded code-division multiple-access (CDMA) systems with random spreading sequences. The modifications are based on modeling the residual multiple-access interference (RMAI) after subtractive interference cancellation as conditionally Gaussian with time-dependent variance, where the conditioning is on the time-varying user crosscorrelations. A novel estimate of the variance of the total RMAI is presented, and used in the proposed branch metrics. Significant performance gains are demonstrated over the Euclidean branch metric of the standard Viterbi decoder.