Access probe acknowledgement with collision detection

摘要

In an illustrative embodiment of the present invention, a first channel is allocated for transmitting sporadically generated messages from multiple field units to a base station. The first channel is preferably divided into time slots in which a field unit transmits an access request message to the base station for establishing a communication link. In response to an access request message, feedback information is provided from the base station to multiple field units indicating whether a collision was detected on the first channel for a message transmitted in a previous time slot. In an instance when a collision is detected, the field unit will re-transmit an access request message at a previous power level setting based on a random back off time.; If no collision is detected and the base station fails to transmit an acknowledgement message from the base station to the access requesting field unit, the power output level of the field unit is increased for successive message transmissions until the message is received.