es R, Eb/No requirements, and activity factors U. These video, messaging, and other services add their gross chip rates y to the pot. Thus we have a total consumption of CDMA resource for voice, data, and other ser- vices in the form of our gross chip rate y. This value y is a measure of total CDMA re- source required to serve the demand for the full suite of 3G services. From the mathe- matical models in Part 5, summarized in Sec. 30.7, we can estimate the number of cell sectors required. From Eqs. (30.1) and (30.2) we can derive Eq. (31.2) to estimate the number of cells we need: (31.2) where n = estimated cell count k = number of sectors per cell y = gross chip rate C = number of CDMA carriers Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Estimating Wireless Telephone Demand Estimating Wireless Telephone Demand W = CDMA chip rate S = soft- and softer-handoff factor p = power control effect j = orthogonality or joint detection f = other cell interference g = other sector interference h = overhead factor t = occupancy U = utilization The same equation works in both forward and reverse directions, although the terms may have slightly different meanings. For example, j represents orthogonal codes in the forward direction and joint detection in the reverse direction. The soft- and softer- handoff factor S should be set to zero in the reverse direction, where there is no soft handoff. Four new terms appear in Eq. (31.2), the number of CDMA carriers c, the number of sectors per cell k, occupancy t, and utilization U. Most CDMA systems have more than one carrier, so we added the term C to Eq. (31.2) to take this into account. The number of cells is 1/k times the number of sectors, according to the sector plan of k sectors per cell. The value k is the average number of sectors per cell, so if half the cells have three sectors and half the cells 