l notice the delay and will not like it. There is always some significant delay in digital mobile systems due to signal pro- cessing. This is why telephone companies always demonstrate long-distance calls when they show new equipment at conventions. If the call were made within the same room, the delay would be noticeable and irritating. If you wish to test this, simply stand next to a friend and have a mobile-to-mobile conversation while you are watching one an- other. You will notice a delay of about half a second. This is irritating when you can see each other but acceptable when you cannot see the other person. 2.4 Conclusion This chapter ends our theoretical discussion of radio engineering. We will now turn to the equipment and systems that turn theory into reality for hundreds of millions of cel- lular users worldwide. 10 This is not the same as the errors divided by the correct bits. On a very noisy channel, the wrong-divided-by-right value will be a larger number than the BER. 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. Radio Signal Quality 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 The User Terminal A user terminal may be defined as any device in a cellular system that receives forward (downlink) transmissions from a base station and sends reverse (uplink) transmissions to a base station. Of course, the vast majority of these devices are mobile telephones, but with the possible growth in wireless local loop (WLL) and the advent of digital wire- less, this will be changing soon. In this chapter we discuss mobile phones as com- ponents of the cellular system and then go on to look at some other types 