AT+CPSMS

Power Protocol

Mobile stations use the at+cpsms sequence to negotiate sleep cycles with the core network during initial attach or periodic tracking area update procedures. The base station responds with assigned timer values that may differ from those requested based on local traffic load or carrier policy. Precise coordination between the modem and the tower ensures the device stays available for expected data payloads while minimising battery draw.

Failure to match the accepted values during a radio resource control connection setup results in immediate session termination by the network controller.

State Transition

Network interface hardware enters a deep sleep condition upon the successful completion of an at+cpsms handshake. During this period the radio transceiver shuts down to save energy while the modem keeps the internal context stored in non-volatile memory. Incoming paging messages trigger a hardware interrupt to wake the module from this low power status.

Latency increases during this transition as the device must reacquire the synchronization signals from the sector antenna before successful data transmission resumes.

Integration Constraint

System designers verify the at+cpsms configuration against the specific battery budget and reporting requirements of the end application. Field results show that excessive active time settings increase the drain on the power supply without providing a functional benefit to data throughput. Validating these settings requires monitoring the current draw during both the active window and the deep sleep phase in a controlled radio frequency environment.

Testing confirms that the modem correctly ignores incoming packets when the sleep timer prohibits radio activity.