ivity on neigh- boring cells. In conventional reuse, interference from neighboring cells reduces call quality but not call capacity. In contrast, the CDMA channel capacity is variable and depends on the call volumes in neighboring cell sectors, a kind of global capacity even without call overflow. In Sec. 30.6 on CDMA soft blocking we discuss how we can use this global capacity in CDMA engineering to mitigate some of the capacity loss other-cell and other-sector interference. 12.5.9 Nonlocal service quality The last notion in traffic engineering we want to address, because it is new in wireless engineering, is the concept that service quality in one area depends on what is hap- pening somewhere else, sometimes moment by moment. We have changing conditions in the landline network, and even some strange stories where conditions in one area changed and another area had a service problem. However, these are considered strange. In wireless, however, it is normal day-to-day reality that radio channels on one side of town affect cellular performance and capacity on the other side. The ball game lets out, and all other cells sharing the same channel set have more interference. This is not a new or deep concept in radio, of course, but it is a little bit strange to those who think in telephony terms. 12.6 Conclusion This introduction to telephony engineering issues lays the groundwork for under- standing the CDMA capacity and engineering issues we will discuss in Parts 5, 6, and 7. 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 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. Source: CDMA CAPACITY AND QUALITY OPTIMIZATION Chapter Telephone Transport