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Proceedings Paper

Multicarrier CDMA: blind multiuser detection schemes
Author(s): Mahadeo Digamber Kokate; T.R. Sontakke
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Paper Abstract

Multiple access is an important consideration in the design and implementation of wireless communication systems. In Multicarrier Code Division Multiple Access (MC-CDMA), advantages of Orthogonal Frequency Division Multiplexing (OFDM) and Code division Multiple Access (CDMA) are integrated. For the future mobile broadband systems of data rates up to 155Mbps, the channel fluctuations are usually much slower than the transmission rate. In these systems, multiple access interference (MAI) becomes an intrinsic factor for severe performance degradation that necessitate the application of signal processing techniques to improve the quality of system. Multiuser Detection (MUD) has been proposed as a solution to MC-CDMA system with interference limited capacity recovery technique. To mitigate MAI, various MUD techniques are proposed in literature. Maximum likelihood optimum detector is complexity sensitive. EGC and MRC are inconvenient for long codes while zero forcing (ZF) and decorrelator detector suffer from noise enhancement. The optimal detection requires knowledge of signature waveforms and transmit power level for each user. The time varying nature of channel and multipath environment of mobile communications require frequent training to the conventional MUD receiver. Most multicarrier systems have asynchronous and uncoordinated transmission, where reliance on frequent training is cumbersome. This implies that the need for blind adaptive receiver is more evident in multiple access channels than in single user channels. A sub-optimal linear detection solution is presented in this paper. The blind multi user MMSE detector is derived to suppress the noise enhancement side effect in zero forcing detector. A Blind adaptive technique, with subspace approach is considered showing computational performance improvements.

Paper Details

Date Published:
Proc. SPIE 5284, Wireless Communications and Networks, ; doi: 10.1117/12.520312
Show Author Affiliations
Mahadeo Digamber Kokate, Pune Univ. (India)
T.R. Sontakke, SRTM Univ. (India)

Published in SPIE Proceedings Vol. 5284:
Wireless Communications and Networks
Chih-Lin I; Jiann-An Tsai; Hequan Wu, Editor(s)

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