Method for locating a mobile communication device

• US 20080153509A1
• Filed: 12/21/2006
• Published: 06/26/2008
• Est. Priority Date: 12/21/2006
• Status: Abandoned Application

• Current Assignee: Spectralink Corporation (Mobile Devices Holdings LLC)
• Original Assignee: Spectralink Corporation (Mobile Devices Holdings LLC)
• Inventors: Piekarski, Christopher
• Application Number:
  US11/643,510
• Publication Number:
  US 20080153509A1
• Time in Patent Office: Days
• US Class Current: 455/456.2
• CPC Class Codes: G01S 19/48 by combining or switching between position solutions derived from the satellite radio beacon positioning system and position solutions derived from a further system
• CPC Class Codes: G01S 5/0289 of multiple transceivers, e.g. in ad hoc networks
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A wireless communication network includes a number of wireless communication devices capable of sending and receiving wireless communication signals and capable of receiving geographic positioning signals from a satellite that they can use to calculate their geographic position. In the event that one wireless communication device moves into an environment in which it is unable to receive a geographic positioning signal, this wireless device is able to establish an ad hoc network with at least two other wireless devices in the network and to retrieve geographic position information from the two other devices. Furthermore, this device can use time of flight information between itself and the other two wireless devices to calculate the distances between it and each of the two other wireless devices that can be utilized to calculate, in combination with the geographic positions of the other two wireless devices, its geographic position.

Claims

1. In an ad hoc wireless communication network including a plurality of wireless:

communication devices capable of receiving geographic positioning signals from a satellite, a method for determining the position of one of the wireless communication devices not currently able to receive a global positioning signal comprising the steps of;

a first one of the wireless communication devices detecting the absence of a geographic positioning signal and broadcasting a message to the other wireless communication devices within range that includes a request for the current geographic position information stored at the other wireless communication devices;

at least two of the other wireless communication devices receiving the broadcast geographic position request message sent by the first wireless communication device and each of the at least two other wireless communication devices responding by transmitting a message containing their geographic position information;

the first one of the wireless communication devices receiving a response from each of the at least two other wireless communication devices, detecting and storing an indication of the signal quality of the communication link over which each response message is transmitted and detecting and storing the geographic position information contained in each response message;

the first one of the wireless communication devices transmitting a first distance determination request message to a first one of the two other wireless communication devices and determining and storing the transmission time of the message;

the first one of the other plural wireless communication devices receiving the first distance determination request message and immediately sending a first distance determination response message to the first one of the wireless communication devices;

the first one of the wireless communication devices receiving the first distance determination response message, determining and storing the receiving time of the message and using the stored first distance determination request message transmission time and the stored first distance determination response message receiving time to calculate a first round trip time and storing the first round trip time;

the first one of the wireless communication devices transmitting a second distance determination request message to a second one of the two other wireless communication devices and determining and storing the transmission time of the message;

the second one of the other plural wireless communication devices receiving the second distance determination request message and immediately sending a second distance determination response message to the first one of the wireless communication devices;

the first one of the wireless communication devices receiving the second distance determination response message and determining and storing the receiving time of the message and using the stored second distance determination request message transmission time and the stored second distance determination response message receiving time to calculate a second round trip time and storing the second round trip time;

the first one of the wireless communication devices using the stored geographic position information received from each of the other first and second wireless communication devices to calculate a distance between the first and second other wireless communication devices and storing this as a first distance;

the first one of the wireless communication devices using the stored first round trip time to calculate a distance between it and the first one of the other two wireless communication devices and storing this as a second distance and the first one of the wireless communication devices using the stored second round trip time to calculate a distance between it and the second one of the other two wireless communication devices and storing this as a third distance; and

the first one of the wireless communication devices using a triangulation technique and the stored first, second and third distances and the stored geographic positions of the two other wireless communication devices to calculate its geographic position and storing this position.

2. The method of claim 1 further comprising the step of:

comparing the stored, calculated geographic position of the first wireless communication device with a last known geographic position of the first wireless communication device to be less than a predetermined distance and marking the stored, calculated geographic position of the first wireless communication device as a verified position.

3. the method of claim 1 wherein the step of calculating the second stored distance includes dividing the first stored round trip time by two and multiplying the result by the speed of light.

4. the method of claim 1 wherein the step of calculating the third stored distance includes dividing the second stored round trip time by two and multiplying the result by the speed of light.

5. the method of claim 1 in which at least the first communication device wireless is a mobile phone.

6. the mobile phone in claim 5 operates to transmit and receive any one of a voice message, a text message and an emergency message.

7. the calculated geographic position of the first wireless communication device of claim 1 is comprised of a latitudinal and a longitudinal coordinate.

8. the mobile phone of claim 5 operates according to cellular technology principles.