Method and system for battery life improvement for low power devices in wireless sensor networks
A method at a sensor module within a sensor system for communicating with a gateway, the method including storing a timing profile for communications with the gateway; waking a radio core of the sensor module at a threshold time prior to a beacon signal being expected from the gateway; sampling a channel for the beacon signal at the radio core; if the beacon signal is detected: waking a processor on the sensor module; exchanging communication with the gateway; and powering down the processor and radio core upon completion of the exchanging communication.
1. A method at a sensor module within a sensor system for communicating with a gateway, the method comprising:
storing a timing profile for communications with the gateway, wherein the timing profile is derived from a learning state on the sensor system, the learning state comprising:
turning on a radio of the sensor module for a first time duration;
detecting a beacon signal from the gateway in a plurality of cycles; and
deriving the timing profile based on the detecting;
powering down a processor of the sensor module;
waking a radio core of the sensor module at a threshold time prior to the beacon signal being expected from the gateway;
sampling a channel for the beacon signal at the radio core while the processor of the sensor module is powered down;
if the beacon signal is detected:
waking the processor on the sensor module;
exchanging communication with the gateway; and
powering down the processor and radio core upon completion of the exchanging communication.
2. The method of claim 1 , wherein the timing profile is received in a message from the gateway.
3. The method of claim 1 , wherein the sampling comprises turning on the radio core periodically for a first portion of a sample cycle and turning off the radio core for a remaining portion of the sample cycle.
4. The method of claim 3 , wherein the beacon signal is longer than the remaining portion of the sample cycle.
5. The method of claim 3 , wherein the sampling utilizes a preconfigured received signal strength indicator threshold.
6. The method of claim 3 , further comprising:
adjusting a clock on the sensor module based on a number of sampling cycles that pass before the beacon signal is detected.
7. The method of claim 1 , wherein the beacon signal includes a clock value, the method further comprising adjusting timing on the sensor module based on the clock value received in the beacon signal.
8. The method of claim 1 , wherein the sensor module and gateway are both power limited devices.
9. A sensor module within a sensor system configured for communicating with a gateway, the sensor module comprising:
a processor; and
a communications subsystem,
wherein the sensor module is configured to:
store a timing profile for communications with the gateway, wherein the timing profile is derived from a learning state on the sensor system, during the learning state the sensor module being configured to:
turn on a radio of the sensor module for a first time duration;
detect a beacon signal from the gateway in a plurality of cycles; and
derive the timing profile based on the detecting;
powering down the processor;
wake a radio core within the communications subsystem of the sensor module at a threshold time prior to the beacon signal being expected from the gateway;
sample a channel for the beacon signal at the radio core while the processor is powered down;
if the beacon signal is detected:
wake the processor on the sensor module;
exchange communication with the gateway; and
power down the processor and radio core upon completion of the exchanging communication.
10. The sensor module of claim 9 , wherein the timing profile is received in a message from the gateway.
11. The sensor module of claim 9 , wherein the sensor module is configured to sample by turning on the radio core periodically for a first portion of a sample cycle and turning off the radio core for a remaining portion of the sample cycle.
12. The sensor module of claim 11 , wherein the beacon signal is longer than the remaining portion of the sample cycle.
13. The sensor module of claim 11 , wherein the sensor module is configured to sample by using a preconfigured received signal strength indicator threshold.
14. The sensor module of claim 11 , wherein the sensor module is further configured to:
adjust a clock on the sensor module based on a number of sampling cycles that pass before the beacon signal is detected.
15. The sensor module of claim 9 , wherein the beacon signal includes a clock value, the sensor module further configured to adjust timing on the sensor module based on the clock value received in the beacon signal.
16. The sensor module of claim 9 , wherein the sensor module and gateway are both power limited devices.
17. A non-transitory computer readable medium for storing instruction code, which, when executed at a sensor module cause the sensor module to:
store a timing profile for communications with the gateway, wherein the timing profile is derived from a learning state on the sensor system, during the learning state the sensor module being configured to:
turn on a radio of the sensor module for a first time duration;
detect a beacon signal from the gateway in a plurality of cycles; and
derive the timing profile based on the detecting;
powering down a processor of the sensor module;
wake a radio core of the sensor module at a threshold time prior to the beacon signal being expected from the gateway;
sample a channel for the beacon signal at the radio core while the processor of the sensor module is powered down;
if the beacon signal is detected:
wake the processor on the sensor module;
exchange communication with the gateway; and
power down the processor and radio core upon completion of the exchanging communication.