Method and wireless communication system for locating wireless transmit/receive units

• US 20050151686A1
• Filed: 12/16/2004
• Published: 07/14/2005
• Est. Priority Date: 12/16/2003
• Status: Active Grant

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Touag, Athmane, Ali, Ahmed
• Granted Patent: US 7,541,977 B2
• Time in Patent Office: Days
• US Class Current: 342/464
• CPC Class Codes: G01S 5/0226 Transmitters
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence
• CPC Class Codes: H04W 60/02 by periodical registration
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A method and system for locating a wireless transmit/receive unit (WTRU) is disclosed. A wireless communication system comprises a plurality of access points (APs). Each AP broadcasts a message indicating class-of-service (COS) types that the wireless communication system supports. After a WTRU registers with one of the plurality of APs, the WTRU receives the broadcast message. The WTRU sets a timer for location update in accordance with an application that the WTRU is running and the COS type with which it is associated. The WTRU transmits a location update frame to the APs at the expiration of the timer, and a location of the WTRU is calculated using the location update frame.

Claims

1. In a wireless communication system comprising a plurality of access points (APs), a method for locating a wireless transmit/receive unit (WTRU) comprising:

each AP broadcasting a message indicating at least one class-of-service (COS) type that the wireless communication system supports, said COS type having an associated location update period;

a WTRU registering with at least one of the plurality of APs and receiving the message;

the WTRU setting a timer in accordance with said location update period;

the WTRU transmitting a location update frame to the APs at the expiration of the timer;

calculating a location of the WTRU using the location update frame.

2. The method of claim 1 wherein the location of the WTRU is determined by calculating time difference of arrival (TDOA) of the location update frame at each of the APs.

3. The method of claim 1, wherein said the COS type is determined by at least one of transmission speed, quality of service, configuration procedures and delay requirements.

4. The method of claim 1 further comprising the step of selecting a predetermined number of APs having strongest signals whereby the WTRU transmits the location update frame to the selected APs.

5. The method of claim 4 wherein the WTRU retransmits the location update frame within a location update period when at least one of the selected APs are busy when the location update frame is transmitted.

6. The method of claim 1 wherein said message is included in a beacon frame.

7. The method of claim 6 wherein said message is included in a capability field of the beacon frame.

8. A wireless communication system for locating a wireless transmit/receive unit (WTRU) comprising:

a plurality of access points (APs), each AP comprising;

means for broadcasting an indication of at least one class-of-service (COS) type that the wireless communication system supports; and

means for calculating the time difference of arrival TDOA values of a location update frame transmitted from a WTRU;

a WTRU comprising;

a timer for determining when to send the location update frame, the timer being based, at least in part, on the COS type of an application that the WTRU is running is a part; and

means for transmitting the location update frame to the APs at the expiration of the timer; and

a network entity for calculating a location of the WTRU using the time difference of arrival values collected from the APs.

9. The system of claim 8 wherein the location of the WTRU is calculated by a triangulation method.

10. The system of claim 8 wherein the COS type is determined by at least one of transmission speed, quality of service, configuration procedures and delay requirements.

11. The system of claim 8 wherein the WTRU further comprising a means for selecting a predetermined number of APs having strongest signals, whereby the WTRU transmits the location update frame to the selected APs.

12. The system of claim 11 wherein the WTRU retransmits the location update frame within a location update period when one or more of the selected APs are busy at the time of the transmission of the location update frame.

13. The system of claim 8 wherein the indication is included in a beacon frame.

14. The system of claim 13 wherein the indication is included in a capability field of the beacon frame.