Vehicle telematics unit power management

1. A method of power management of a telematics unit in a vehicle, comprising the steps of:

(a) determining that the vehicle is unpowered;

(b) entering a first power-saving mode at the telematics unit, wherein the telematics unit scans periodically for a cellular signal in the first mode, and wherein the telematics unit increases a scan period from a baseline scan period in response to a determination that the cellular signal is below a predetermined signal strength threshold, and resets the scan period to the baseline scan period when the cellular signal is determined to be above the predetermined signal strength threshold;

(c) determining that the vehicle is in a signal fluctuation region of a cellular network, including determining that the strength of a cellular signal from the network intermittently varies greater than and less than the predetermined signal strength threshold such that the resetting of the scan period in response to the determination that the cellular signal is above the predetermined signal strength threshold while in the first power-saving mode would consume a power budget before the expiration of a predetermined time duration; and

(d) based on steps (a), (b), and (c), meeting the power budget by entering a second power-saving mode at the telematics unit, wherein the telematics unit reduces power consumption by reducing cellular network usage, and continues the reduced cellular network usage when the signal strength of the cellular network in the signal fluctuation region is detected above the signal strength threshold.

2. The method of claim 1 , wherein the intermittent variance occurs within a predetermined duration of time.

3. The method of claim 1 , wherein the threshold is greater than or equal to −107 dBm in an LTE cellular network, greater than or equal to −105 dBm in a WCDMA cellular network, and greater than or equal to −105 dBm in a GSM cellular network.

4. The method of claim 1 , further comprising step (e) exiting the second power-saving mode if it is determined that the vehicle engine is turned ON or if a predetermined portion of the vehicle power budget has expired.

5. The method of claim 4 , wherein the power budget is 1440 milli-Amp-hours (mAh) and the predetermined time duration is 240 hours.

6. A method of claim 1 , further comprising configuring a telematics unit with a software application carried by a non-transitory computer medium prior to steps (a), (b), and (c).

7. The method of claim 1 , wherein the signal fluctuation region is at or near an outer edge of a cellular region.

8. The method of claim 1 , wherein the signal fluctuation region is within a cellular region, the fluctuating signal being due to an obstruction of at least some portion of the cellular signal.

9. A vehicle telematics unit, comprising:

a processor; and

a non-transitory computer readable medium having a network access device (NAD), comprising one or more software application programs stored on the computer readable medium to be executed by the processor, the programs including instructions to:

identify instances when the vehicle is in an unpowered state, wherein the NAD enters a power-saving mode, wherein the NAD scans periodically for a cellular signal in the power-saving mode, and wherein the NAD increases a scan period from a baseline scan period in response to a determination that the cellular signal is below a predetermined signal strength threshold, and resets the scan period to the baseline scan period when the cellular signal is determined to be above the predetermined signal strength threshold;

determine that the wireless signal received by the NAD is a fluctuating signal, wherein the strength of a cellular signal from the network intermittently varies greater than and less than the predetermined signal strength threshold such that the resetting of the scan period in response to the determination that the cellular signal is above the predetermined signal strength threshold while in the power-saving mode would consume a power budget before the expiration of a predetermined time duration; and,

based on the identify and determine instructions, meet the power budget by altering the power-saving mode to modify a listening mode of the NAD to limit the power consumed by the telematics unit so that the telematics unit may be intermittently powerable throughout the duration of a predetermined vehicle power budget and maintain the modified listening mode when the signal strength signal of the cellular network in the signal fluctuation region is detected above the signal strength threshold.

10. The method of claim 1 , further comprising step (e) exiting the second power-saving mode and ceasing cellular network usage until the vehicle is powered ON if it is determined that a predetermined duration of a vehicle power budget has expired.

11. The method of claim 10 , wherein the power budget is 1440 milli-Amp-hours (mAh) and the predetermined time duration is 240 hours.

12. The method of claim 1 , further comprising altering at least one of a listening portion, a scanning portion, and a time cycle of the telematics unit in response to determining that the vehicle is in the signal fluctuation region of the cellular network.

13. The method of claim 1 , further comprising shortening a listening portion of a time cycle of the telematics unit in response to determining that the vehicle is in the signal fluctuation region of the cellular network.

14. The method of claim 1 , further comprising increasing a time cycle of the telematics unit in response to determining that the vehicle is in the signal fluctuation region of the cellular network.

15. The method of claim 1 , further comprising scanning for a cellular signal less frequently in response to determining that the vehicle is in the signal fluctuation region of the cellular network.

16. A method of power management of a telematics unit in a vehicle, comprising the steps of:

(a) determining that the vehicle is unpowered;

(b) entering a first power-saving mode at the telematics unit, including scanning for a cellular signal periodically with the telematics unit, wherein the telematics unit increases a scan period from a baseline scan period in response to a determination that the cellular signal is below a predetermined signal strength threshold, and resets the scan period to the baseline scan period when the cellular signal is above the predetermined signal strength threshold;

(c) determining that the vehicle is in a signal fluctuation region of a cellular network, wherein a signal strength of the cellular network is varying above and below the signal strength threshold such that the resetting of the scan period in response to the determination that the cellular signal is above the predetermined signal strength threshold while in the first power-saving mode would consume a power budget before the expiration of a predetermined time duration; and

(d) based on steps (a) and (c), meeting the power budget by entering a second power-saving mode at the telematics unit, wherein the telematics unit scans for a cellular signal less frequently and continues to scan less frequently when the signal strength of the cellular network in the signal fluctuation region is detected above the signal strength threshold.

17. The method of claim 16 , further comprising, after steps (c) and (d):

(e) detecting that the vehicle is not within a signal fluctuation region of the cellular network, and increasing a scan frequency in response to the detection when the signal strength of the cellular network is detected above the signal strength threshold.

18. The method of claim 16 , wherein the signal fluctuation region is at or near an outer edge of a cellular region.

19. The method of claim 16 , wherein the signal fluctuation region is within a cellular region, the fluctuating signal being due to an obstruction of at least some portion of the cellular signal.