 Business-Case Models Modeling for CDMA Cents Ounces Figure 46.2 Linear approximation of postage function. accomplish here is to provide an illustrative example of the cost-calculation process. In this example we are calculating the cost per subscriber SO that our financial backers can feel comfortable with the money they are investing in our wireless telephone system. Let us start by considering a cdmaOne system with five carriers, as summarized Table 46.1. All costs are in U.S. dollars. We will go through each level of the hierarchy. A full-blown cost study would include operations, administration, and maintenance (OA&M), along with a more complete and detailed list of equipment components at each level. We start with the subscriber who has a user terminal. The cdmaOne user terminal is mobile telephone that costs about $300. 3 Each subscriber generates 0.02 erlang of peak- time demand. In other words, the busy-hour load is 0.02 times the number of subscribers. Each equipped channel has a $200 channel card plugged into a $1600 channel back- plane that has enough slots for 32 channel cards. In our example, each DS-1 of back- haul transport can carry 100 voice calls. To our investors, the average tariff rate $200 per month for a backhaul DS-1 is worth $40,000 in up-front money. We are using the postage-stamp model described earlier to add 1/32 of a channel backplane and 1/100 of back- haul DS-1 to the cost of a channel card. These are marked with (P) in Table 46.1. 3 The subscriber probably sees a much lower price for the mobile telephone. This is SO because much of the cost of the user terminal is built into the monthly rate. 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. Business-Case Models Business-Case Models Cells Figure 46.3 Linear approximation of MSC cost. We are going to equip each carrier of each sector with 24 voice channels. Wit