Issues of Modeling Fading Dispersive Channels in DS／CDMA Communications

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Issues of Modeling Fading Dispersive Channels in DS/CDMA Communications

This paper compares the following channel representations:the time-variant channel im-pulse response(CIR),the tapped delay-line(TDL) channel representation and the equivalent dis-crete-time(EDT) channel model in modeling direct-sequence code division multiple access(DS/CDMA) systems communicating over frequency-selective Raylengh fading,wide-sense-stationary uncorrelated-scattering(WSSUS)channels.Emphasis is given to comparing degrees of simplicity offered by these representations to analytic works and computer simulations using PAKE re-ceivers.It is shown that (i)the use of TDL or EDT chnnel model simplifies analytic works and computer simulations but using the time-variant CIR does not;(ii)the TDL and EDT channel models provide approximately the same degree of simplicity.However, the TDL channel represent-tation is subject to a number of rigid assumptions which limits its area of application,while the EDT channel model is not.It is concluded that the EDT channel model is the most appropriate one among the three channel representations considered.