Reverse Link Bandwidth Efficiency of a Spectrally Overlapped CDMA System

Duk Kyung KIM  Fumiyuki ADACHI  

IEICE TRANSACTIONS on Communications   Vol.E85-B   No.4   pp.758-768
Publication Date: 2002/04/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Terrestrial Radio Communications
spectrally overlapped CDMA system,  pulse shaping filter,  fast power control,  multiple cell,  multipath fading,  

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The reverse link bandwidth efficiency of a spectrally overlapped CDMA system with fast transmit power control is evaluated to find the optimum overlapping, where the bandwidth efficiency is defined as the maximum aggregate bit rate of all subsystems per unit bandwidth (bps/Hz). Single and multiple cell environments are considered. Besides the rectangular chip pulse, the impact of a pulse-shaping filter is discussed. It is found that the raised cosine spectrum pulse shaping helps to increase the bandwidth efficiency and strict pulse shaping filter problem can be avoided if a large number of subsystems are overlapped. It is also found that the optimum carrier spacing remains unchanged irrespective of the power delay profile shape of the multipath channel, whether multipath fading exists or not, and whether a single cell or multiple cell system is considered. However, the bandwidth efficiency strongly depends on them and the impacts of the related parameters are discussed.