BATTERY SAVING MECHANISM FOR A PORTABLE COMMUNICATION DEVICE
Original Publication Date: 1999-Jun-01
Included in the Prior Art Database: 2002-Aug-15
Ivana the iDEN power user had a problem. She traveled by air quite a bit, and she took his iDEN subscriber everywhere she went. She noticed that when she arrived at her destination, her iDEN sub- scriber was powered off because the battery had died mid-flight. What could Ivana do? In a trunking communication system, when a user moves out of a coverage area and forgets to power off his portable subscriber unit, the subscriber unit continues to search for cell sites to camp onto and register. After the portable has searched for a certain period of time and has not found a site, the portable enters a "sleep" mode to save battery life. While in "sleep" mode, the portable does not search for cell sites, which saves battery life. After remain- ing in "sleep" mode for a certain period of time, the portable returns to a "scan" mode, in which the portable again searches (scans) for cell sites. However, if the portable is left on for a long time while it is out of the coverage area, it will periodi- cally continue to search for cell sites until the bat- tery eventually dies. In a typical scenario, if the powered-on portable is kept out of the coverage area for more than ten hours, the portable's battery dies, and the portable cannot be used without a fresh battery.