ISSN : 1796-2021
Volume : 3    Issue : 5    Date : October 2008

Cell Site Power Characterization for Multi-rate Wireless CDMA Data Networks Using Lognormal Approximation
Ashraf S. Hasan Mahmoud
Page(s): 47-53
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An analytical model is developed to solve the power-rate assignment problem for multi-rate CDMA systems and
calculate the probability density function (PDF) for the downlink traffic power as a function of the bit rate assignment
scheme, the target link quality figure, and the other network parameters. This paper proposes the use of the
lognormal random variable as an approximation for an empirical parameter (denoted herein by fi) that is needed to
solve the energy per-bit to noise spectral power density equation for scheduled data bursts. The approximation
depends on matching the mean and standard deviation of the lognormal variable to the mean and standard deviation
of the empirical parameter fi where the matching depends only the radio frequency (RF) path loss model and the
shadowing process standard deviation. The paper presents example calculations for the cumulative probability
distribution (CDF) of the downlink traffic power and outage probabilities for a general CDMA system assuming
specific scenarios of data bit rate assignments. The study also compares between analytical results and those
obtained using conventional Monte-Carlo simulations. Comparisons indicate that the developed model provides an
appropriate mechanism to approximate both the PDF or CDF, and the outage probability for the cell site total
downlink traffic power.

Index Terms
code division multiple access, radio resource management, call admission control, burst scheduling