nnel bit stream has a busy/idle bit to tell the mobile when it is safe to transmit its seizure message. Two mobiles could see the same idle bit and transmit at the same time, causing a message collision. When this happens, the mobile telephone is required to wait a random amount of time before trying again. The mobile telephone makes 10 seizure attempts, and the call fails if it does not get through. The cell may not be able to serve the call. The cell goes through all its logical faces (Sec. 5.2.3) and selects the best one where the mobile has adequate path gain based on signal strength measurement. The mobile telephone seizure message is sent with a power level directed by the system limited by its own maximum power level. If no logical faces are available, then the mobile telephone is directed to retry a list of alternate cells. In the case of a smaller-growth cell where all the access threshold lev- els are set high, there may be regions where the mobile telephone chooses the cell and there is no adequate server. Such calls also are directed to retry alternative cells. There are directed retry counters to make sure that the mobile does not get into an endless directed retry loop. 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. Analog Wireless Telephony (AMPS) Analog Wireless Telephony (AMPS) Once the seizure message reaches a suitable cell, the cell sends a message with voice channel and initial mobile transmit power level. If the mobile telephone does not acquire SAT within a few seconds, then the call is lost. If the base station receiver does not receive the SAT returned from the mobile tele- phone, then the call is lost. Once the call has passed through all these stages, a two-way stable voice link is es- tablished, and the subscriber is ready to be involved. In the case of a mobile origina- tion, the microphone and speaker are turne