less efficient air interface. This is a bad thing to do just from a radio utilization stand- point, but there are other consequences as well. The CDMA subscriber is paying good money for a suite of services. It is unlikely that the older FDMA or TDMA system is go- ing to have all those services available. The third-generation (3G) services are certainly not going to be found on older systems used for traffic overflow. A high rate of intermode handoffs could be a sign of poor CDMA coverage. If we see a steady stream of intermode handoffs from a particular cell sector, then we should in- spect the rate of intermode handoffs when the cell sector is not busy. If there is still sig- nificant intermode handoff activity when the sector is lightly loaded, then we should conclude that there is a pocket of poor coverage subscribers are moving into and thus losing their CDMA signal. The high intermode handoff rate is telling us to improve the radio coverage of a CDMA base station. A high rate of intermode handoffs could be a sign of CDMA congestion. If we see a high rate of intermode handoffs only when the CDMA carrier is busy, when power lev- 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. Measuring System Performance for Growth Measuring System Performance for Growth els are high, then we suspect that the older technology is acting as an overflow medium for an overloaded CDMA air interface. The high intermode handoff rate is telling us to improve the radio capacity of a CDMA base station. We should be keeping records by cell sector and by time of day of the rate of inter- mode handoff activity. In particular, we should be watching that rate as a function of how busy the CDMA system is when those intermode handoffs occur. 39.5 Backhaul Congestion The backhaul network should be designed and engineered for very low blocking. The packet streams from base