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【正文】 of the new channel simulator. All of the results discussed in this section correspond to the transmission of simple directsequence codedivisionmultipleaccess waveforms consisting of sequences of rectangular chip waveforms. All spreading codes were randomly generated and the chip duration and spreading gain varies depending on the characteristics of the channel being simulated. A symbol duration of 1 millisecond was assumed for all of the channels, and the channel scattering function was assumed to have the following Gaussian 1 7 7 1 parametric form:where StVtul = SdT, . The channel fading parameters for each of the four cases illustrated here are summarized in Table 1 . The simulation results for each of the four cases are presented in Figures 25. As these figures indicate, the simulation results agree well with the expected channel behavior under each of the fading scenarios considered.5. Conclusions and Future WorkPreviously developed simulators for multipath fading channels were designed primarily for a particular type of channel. By incorporating both Doppler and delay diversity in the simulator design as well as correctly modeling the correlation between channel taps, a generalpurpose multipath simulator has been developed. Simulation results for several different fading scenarios agree well with anticipated channel behavior and thus verify the correctness of the simulator.The current implementation of the simulator assumes that the channel behavior decorrelates in one symbol interval. Hence, it is necessary to use very long symbol intervals to accurately simulate slow fading characteristics. This plicates use of the simulator and creates unnecessarily high putational plexity. Current work is focused on improving the sirnulator to model correctly the correlation between symbol intervals.References :[1] G. L. Stuber, Principles of Mobile , MA: Kluwer Academic Publisher, 1996.[2] P. A. Bello, ”Characterization of Randomly TimeVariantLinear Channels,” IEEE Transactions on Communications Systems, vol. CSI 1, pp. 360393, Dec., 1963.[3] R. H. Clarke, “A Statistical Theory of MobileRadioReception,” Bell Systems Technical Journal, vol. 47, pp,9571000,1968.[4] J. M. Goodman, HF Communrcations Science ond Technology. New York, NY: Van Nostrand Reinhold,1992.[5] P. Hoeher, “A Statistical DiscreteTime Model for SWWUS Multipath Channels,” IEEE Transactions on Vehicular Technology, vol. 41, pp. 461468, Nov., 1992.[6] W. C. Jakes, Jr., Microwave Mobile Communications. New York, NY: John Wiley amp。 Sons, 1974.[7] J. S. Sadowsky and K. Venceslav, “On the Correlation and Scattering Functions of the WSSUS Channel for Mobile Communications,” IEEE Transactions on t’ehicular Technology, vol. 47, pp. 270282, Feb., 1998.[8] . Yip and . Ng, “Efficient Simulation of Digital Transmission Over WSSUS Channels,” IEEE Transactionson Communications, vol. 43, pp. 29072912, Dec., 1995.[9] T. S. Rappaport, Wireless Communications, Principles amp。Practice. Englewood Cliffs, NJ: Prentice Hall, Inc., , 1968.[10] J. G. Proakis, Digital Communications, Second ed. New York: McGrawHill, Inc., 1989.[11] A. Sayeed and B. Adhang, “Joint MultipathDoppler Diversity in Mobile Wireless Communications,” IEEETransactions on Communications, vol. 47, no. 1, pp. 123132, Jan., on Communications, vol.
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