 a wireless network is far less straightforward than it is in landline tele- phony, but the big difference is in the radio link. As far as transport is concerned, the wireless telephone system is still basically a telephone transport network. The overflow issues are a bit more complex due to handoffs and due to the mobility of call setup. We must take them into account when planning capacity and overflow, but we do not need to introduce any radically new ideas. We can use the same thinking we would use planning PSTN capacity. In conventional reuse, a busy cell sector can direct extra traffic to other cell sectors, providing traffic overflow for the air interface, equivalent to local-loop overflow on the PSTN. Knowing traffic can overflow allows us to be more aggressive in our traffic en- gineering, as discussed in Sec. 23.4 than we would be without overflow. We can block more calls from each sector when they have a significant chance of having somewhere else to be served. In CDMA, however, sending extra traffic to another cell sector is generally not a good idea. When we solve the CDMA equations in Sec. 28.1, we see that adding traffic to the wrong sector is even more damaging to the right sector than simply overloading the 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. Telephony Engineering Concepts Telephony Engineering Concepts right sector. Because all the CDMA sectors use the same frequency band, the interfer- ence impact of a call is minimized by serving it on the cell sector with the best radio path (highest path gain), where it can operate at what probably will be the lowest ac- ceptable power level. There is another, more subtle kind of overflow in CDMA. In conventional reuse and landline telephony, we have some number of telephone lines, and we can keep serving calls until they run out. This number remains fixed, regardless of act