JPL's Wireless Communication Reference Website

Chapter: Network Concepts and Standards
Section: Data Systems, CDPD


Mobile End Station (M-ES)

Contributed by Yi-Bing Lin

A CDPD user communicates with the CDPD network by using the M-ES. The physical location of M-ESs may change from time to time, but continuous network access is maintained. An M-ES may be

The M-ES consists of three parts:

A sleep mode is provided in CDPD to allow an idle M-ES to shut off power for a predefined period. To ``wake up'' the M-ES, the MDIS periodically broadcasts a notification message to provide the list of M-ESs that are receiptants of the frames queued in the MDIS. The M-ES periodically activates its receiver to listen to the broadcast notification message. If its name is found in the list, the M-ES leaves the sleep mode by sending a message to the MDIS. With this mechanism, the battery life of the M-ES can last longer (12-hour battery life with CDPD power-saving mode has been reported in the commercial products).
An M-ES may repeatedly transmits long bursts. To prevent this channel hogging situation, a minimum time period is defined between two bursts of an M-ES to ensure that other M-ESs have the chance to access the reverse link.



JPL's Wireless Communication Reference Website Yi-Bing Lin (Author) and Jean-Paul M.G. Linnartz (Ed.), 1996.