Optimal Power Distribution Control for Multicode MC-CDMA with Zero-Forcing Successive Interference Cancellation
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Optimal Power Distribution Control for Multicode MC-CDMA with Zero-Forcing Successive Interference Cancellation Mizhou Tan Agere Systems, 1110 American Parkway NE, Allentown, PA 18109, USA Email: [email protected]
Christian Ibars Centre Tecnol`ogic de Telecomunicacions de Catalunya, C/Gran Capit`a 2-4, 08034 Barcelona, Spain Email: [email protected]
Yeheskel Bar-Ness Center for Communications and Signal Processing Research (CCSPR), Department of Electrical and Computer Engineering (ECE), New Jersey Institute of Technology (NJIT), University Heights, Newark, NJ 07102, USA Email: [email protected] Received 10 August 2003; Revised 11 March 2004 Multicarrier CDMA (MC-CDMA) has become a promising candidate for future wireless multimedia communications for its robustness to frequency-selective fading and its flexibility in handling multiple data rates. Among different multirate access schemes, multicode MC-CDMA is attractive for its high performance, good flexibility in rate matching, and low complexity. However, its performance is limited by self-interference (SI) and multiuser interference (MUI). In this paper, a zero-forcing successive interference cancellation (ZF-SIC) receiver is used to mitigate this problem for multicode MC-CDMA. Furthermore, optimal power distribution control (PDC), which minimizes each user’s bit error rate (BER), is considered. Our results show that, in correlated Rayleigh fading channels, the ZF-SIC receiver integrated with the optimal PDC dramatically improves the performance of the multicode MC-CDMA system in comparison with other receivers proposed in the literature. Moreover, the optimal PDC significantly outperforms the PDC based on equal BER criterion, particularly under a short-term transmit power constraint. Keywords and phrases: multicode, multicarrier CDMA, zero-forcing, successive interference cancellation, power distribution control.
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INTRODUCTION
Multicarrier CDMA (MC-CDMA) combines multicarrier modulation (MCM) and DS-CDMA, and is characterized by its robustness to channel frequency selectivity and its simple receiver structure [1, 2, 3, 4]. Multirate MC-CDMA schemes were proposed to support multimedia applications in future wireless communications [5]. Multicode MCCDMA is one of the multirate access schemes in which different symbols of each user are transmitted in parallel by employing different spreading codes. Compared with other multirate access schemes, multicode MC-CDMA presents better performance, higher rate matching capability, and lower complexity [6]. However, the capacity of MC-CDMA is mainly limited by self-interference (SI)1 and 1 SI
denotes the interference among different symbols of the same user.
multiuser interference (MUI). To mitigate this problem, many interference cancellation schemes have been proposed, among which successive interference cancellation (SIC) is highly desirable due to its ability to increase capacity while maintaining low complexity, its compatibility to existing systems, and its easy accommodation of strong error-correcting code
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