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Cell Site Power Characterization for Multi-rate Wireless CDMA Data Networks Using Lognormal Approximation

Ashraf S. Hasan Mahmoud
Computer Engineering, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia

Abstract—An analytical model is developed to solve thepower-rate assignment problem for multi-rate CDMAsystems and calculate the probability density function (PDF)for the downlink traffic power as a function of the bit rateassignment scheme, the target link quality figure, and theother network parameters. This paper proposes the use ofthe lognormal random variable as an approximation for anempirical parameter (denoted herein by fi) that is needed tosolve the energy per-bit to noise spectral power densityequation for scheduled data bursts. The approximationdepends on matching the mean and standard deviation ofthe lognormal variable to the mean and standard deviationof the empirical parameter fi where the matching dependsonly the radio frequency (RF) path loss model and theshadowing process standard deviation. The paper presentsexample calculations for the cumulative probabilitydistribution (CDF) of the downlink traffic power and outageprobabilities for a general CDMA system assuming specificscenarios of data bit rate assignments. The study alsocompares between analytical results and those obtainedusing conventional Monte-Carlo simulations. Comparisonsindicate that the developed model provides an appropriatemechanism to approximate both the PDF or CDF, and theoutage probability for the cell site total downlink trafficpower.

Index Terms—code division multiple access, radio resourcemanagement, call admission control, burst scheduling

Cite: Ashraf S. Hasan Mahmoud, "Cell Site Power Characterization for Multi-rate Wireless CDMA Data Networks Using Lognormal Approximation," Journal of Communications, vol. 3, no.5, pp. 47-53, 2008.