Power management method for portable communication device

A portable device in an emergency response system at least including the portable device and a central station, comprising:

• a global navigation satellite system (GNSS) receiver configured to obtain first location information;
• a wireless transceiver configured to obtain second location information and to communicate with the central station;
• a memory storing program instructions;
• and
• a processor configured to execute the program instructions to perform:
• in a normal mode, sending at a first interval the first location information obtained from the wireless transceiver to the central station via the wireless transceiver, wherein the GNSS receiver is placed in a low power mode or a power-off mode;
• in an emergency mode, sending in a predefined sequence and priority the first location information obtained from the wireless transceiver and the second location information obtained from the GNSS receiver to the central station via the wireless transceiver, wherein the GNSS receiver is placed in a full power mode;
• and
• in response to failing to obtain the first location information from the wireless transceiver, entering the emergency mode and skipping sending the first location information to the central station;
• wherein the GNSS receiver consumes more power in the full power mode than in the low power mode or the power-off mode, and each of the first location information and the second location information includes a user ID and account information of the portable device.

A central station in an emergency response system at least including a portable device and the central station, comprising:

• a memory storing program instructions;
• and
• a processor configured to execute the program instructions to perform:
• receiving first location information sent from the portable device at a first interval;
• in response to missing the first location information sent from the portable device at the first interval for a number of times exceeding a first threshold, sending a first command to the portable device to force the portable device to enter an emergency mode, wherein the first location information is obtained from a wireless transceiver of the portable device;
• and
• in response to receiving again the first location information sent from the portable device at the first interval for a number of times exceeding a second threshold, sending a second command to the portable device to force the portable device to exit the emergency mode and enter a normal mode;
• wherein the first threshold and the second threshold are a positive integer.