Huang, Lei (2003) Blind Channel Estimation and Multiuser Detection for Multi-Rate CDMA Communications. PhD thesis, Victoria University.

Abstract

The future wireless communications systems should be able to offer wide variety of applications, which have vastly different quality of service (QoS) requirements. The time-variable QoS may require the support of variable bit rates on the wireless links to the individual users. Multi-rate DS/CDMA is a promising basis on which to support the variable bit rates on the individual wireless links. Currently, the study on channel estimation and multiuser detection for multi-rate DS/CDMA, which makes full use of the nature of multi-rate signals, is still at its early stage. The thesis deals with the application of subspace-based techniques to blind channel estimation and multiuser detection for multi-rate DS/CDMA, including single-carrier and multicarrier scenarios. For the single-carrier case, space-time blind linear multiuser detection is investigated for synchronous dual-rate systems over the AWGN channel. The performance is evaluated analytically. The multi-rate generalization and the asynchronous extension are discussed. Two-stage space-time dual-rate blind detectors are also presented. Furthermore, blind adaptive channel estimation and detection schemes for asynchronous dual-rate systems over frequency-selective multipath channels are developed. In the context of multicarrier DS/CDMA, based on a finite-length truncation approximation on the band-limited chip waveform, blind timing acquisition and channel estimation scheme is proposed for multi-rate systems. The channel estimation error due to the finite-length chip waveform truncation is analyzed by exploiting a first-order perturbation approximation.

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