Multiuser Detection with Multistage Interference Cancellation for Asynchronous Optical CDMA Systems
Date Issued
2004
Date
2004
Author(s)
Lin, Shin-Yi
DOI
en-US
Abstract
For optical code division multiple access (OCDMA) communication systems, the optical orthogonal codes (OOCs) with ideal auto- and cross-correlation properties have been widely studied. Another approach to improve the performance is to employ multiuser detection techniques. In this thesis, we present several multiuser detection (MUD) schemes for OCDMA systems. Characterization of the intensity-modulation/ direct- detection OCDMA system with the avalanche photodiode is addressed. The parallel interference cancellation (PIC) algorithm is applied to OCDMA and results in a multi-stage PIC detector, which is shown to outperform the correlator. A modified partial parallel interference cancellation (PPIC) algorithm for OCDMA is proposed and analyzed. The main concept is to remove only a fractional of the multiuser interference (MUI) instead of complete cancellation when the estimation is poor, and raise this weighting factor as the fidelity of decision and estimation improved. The multistage PPIC detector is found to significantly reduce the degradation due to the MUI and offer excellent performance with complexity proportional linearly to the number of users. With appropriate choice of the weighting factor, OCDMA systems with the PPIC detector will achieve the known-interference lower bound as shown in the simulation and numerical results. Moreover, the code-weight- partition receiver, which can be considered as the modified version of the correlator, is proposed and can be combined with the PIC algorithm. The proposed multiuser detectors in this thesis are of excellent performance and acceptable complexity.
Subjects
平行化干擾消除
光正交碼
光分碼多工系統
多用戶偵測技術
Optical CDMA (OCDMA) Systems
Multiuser Detection
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-93-R91942032-1.pdf
Size
23.31 KB
Format
Adobe PDF
Checksum
(MD5):4641c237dd59dac9e338cde96bd07781