Panic messaging in an ofdm communication system

A system for emergency communication in an OFDM communication system having a base station, comprising:

• a plurality of OFDM wireless communication devices each configured to receive call set-up commands from the base station to assign each of the plurality of wireless communication devices a respective set of tones for use on an uplink and a respective set of tones for use on a downlink;
• each of the wireless communication devices having a transmitter configured to transmit data to the base station on the uplink using the set of tones assigned for use on the uplink;
• each of the wireless communication devices having a receiver configured to receive data from the base station on the downlink using the set of tones assigned for use on the downlink;
• each of the wireless communication devices having an emergency activation button operable to initiate emergency communications;
• and
• each of the wireless communication devices having an emergency message processor to control emergency communications with the base station, the emergency message processor for a selected one of the plurality of wireless communication devices whose emergency activation button has been activated being configured to:
• cause the transmitter of the selected wireless communication device to transmit an emergency message to the base station, the emergency message including identification data to identify the selected wireless communication device;
• cause the receiver of the selected wireless communication device to continuously decode a predetermined emergency OFDM tone to detect an acknowledgement message from the base station indicating that the base station received the emergency message;
• if the acknowledgement message is not received within a first predetermined period of time following the transmission of the emergency message, to cause the transmitter of the selected wireless communication device to increase the effective signal strength of the transmitter to retransmit the emergency message regardless of any power control commands received from the base station;
• and
• if the acknowledgement message is not received within a second predetermined period of time following the retransmission of the emergency message, to cause the transmitter of the selected wireless communication device to increase the effective signal strength of the transmitter to retransmit the emergency message.

A method for emergency communication by a wireless communication device in an OFDM communication system, comprising:

• sensing activation of an emergency activation button to initiate emergency communications;
• using a transmitter to transmit an emergency message to a base station, the emergency message including identification data to identify the wireless communication device;
• using a receiver to continuously decode a predetermined emergency OFDM tone to detect an acknowledgement message from the base station indicating that the base station received the emergency message;
• if the acknowledgement message is not received within a first predetermined period of time following the transmission of the emergency message, increasing the effective signal strength of the transmitter to retransmit the emergency message;
• and
• if the acknowledgement message is not received within a second predetermined period of time following the retransmission of the emergency message, increasing the effective signal strength of the transmitter to retransmit the emergency message.