外文翻译瑞利衰落环境下单蜂窝多载波DS-CDMA系统的频谱效率.docVIP

附录B 外文文献及译文 Spectral efficiency of a single-cell multi-carrier DS-CDMA system in Rayleigh fading P. Varzakas, G.S. Tombras Laboratory of Electronics, Department of Physics, University of Athens, GR-157 84 Athens, Greece Received 8 June 2005; received in revised form 12 September 2005; accepted 11 March 2006 Abstract: The spectral efficiency of a multi-carrier direct-sequence code-division multiple-access (MC/DSCDMA) system operating in a Rayleigh fading environment is investigated and evaluated in terms of the theoretically achievable channel capacity (in the Shannon sense) per user, estimated in an average sense.。This short paper covers operation of the considered system over broadcast communication randomly time-varying channels as applicable to wireless radio networks and single-cell indoor mobile systems and leads to the derivation of a closed-form expression for the achieved spectral efficiency. Furthermore, the relation between the number of the employed sub-carriers and the achieved spectral efficiency is revealed. Keywords: Spectral efficiency; Channel capacity; Multi-carrier modulation; Code-division multiple access; Rayleigh fading; 1. Introduction Based on orthogonal frequency-division multiplexing (OFDM), multi-carrier direct sequence code-division multiple-access (MC/DS-CDMA) has been proposed and investigated in the context of high data rate communication over time-variant channels [1]. In such a MC/DS-CDMA system, the data sequence, multiplied by a spreading sequence, modulates a set of N orthogonal frequency carriers rather than a single one, as it is the case in conventional DS-CDMA. In this paper, we consider the operation of a single-cell MC/DS-CDMA system in a Rayleigh fading environment and evaluate its spectral efficiency in terms of the theoretically achievable channel capacity (in the Shannon sense) per user, on the condition that this is estimated in an average sense. Such an approach is justified by the fact that the spectral efficiency ach