A data collection network supporting roaming terminals which may enter and
exit a sleep mode to conserve power. A plurality of base stations each
periodically transmit pending message indications to those roaming data
collection terminals within range. Instead of requiring the transceiver
within each terminal to always be active, the receiver is activated in
synchrony with the transmissions of pending message indications from at
least one of the base stations. Otherwise, the terminal may deactivate
the transceiver (i.e., place it in a sleep state). The terminal may also
sleep through pluralities of transmissions of pending message
indications, and, thereafter, awake in synchrony to receive subsequent
pending message indications. To minimize noise, the terminal may operate
using a lower frequency system clock when not collecting data. When
collecting data, especially where processing time proves critical, the
system clock frequency is increased.