Supporting emergency calls on a wireless local area network

• US 20060030290A1
• Filed: 05/09/2005
• Published: 02/09/2006
• Est. Priority Date: 05/07/2004
• Status: Active Grant

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Rahman, Shamim Akbar, Zuniga, Juan Carlos, Kwak, Joseph A., Rudolf, Marian
• Granted Patent: US 8,145,182 B2
• Time in Patent Office: Days
• US Class Current: 455/404.100
• CPC Class Codes: H04W 4/90 Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS]
• CPC Class Codes: H04W 76/50 for emergency connections

Abstract

A device for identifying an emergency call in a wireless local area network includes an indicator to identify a call as an emergency call. The indicator can be a bit flag or an information element. The information element can include location information regarding the location of the station that placed the emergency call. This information can be used to located the caller. The location information can be transmitted from the station to an access point separately from an emergency call.

Claims

1. A device for identifying an emergency call in a wireless local area network, comprising:

an indicator to identify a call as an emergency call.

2. The device according to claim 1, wherein said indicator is a bit flag.

3. The device according to claim 2, wherein said bit flag is located in a medium access control frame.

4. The device according to claim 2, wherein said bit flag is located in a request to send frame.

5. The device according to claim 1, wherein said indicator is an information element.

6. The device according to claim 5, wherein said information element includes an emergency call flag.

7. The device according to claim 5, wherein said information element includes a reason code.

8. The device according to claim 5, wherein said information element includes a capability information field, identifying the capabilities of a station placing the emergency call.

9. The device according to claim 5, wherein said information element includes a location information field, containing information to locate a station placing the emergency call.

10. The device according to claim 5, wherein said information element includes a voice codec field, to identify the codec used by a station placing the emergency call.

11. A device for reporting location information of a station in a wireless local area network, comprising:

a location information field.

12. The device according to claim 11, wherein said location information field is located in a medium access control frame.

13. The device according to claim 11, wherein said location information field is periodically transmitted from the station to the network.

14. The device according to claim 11, wherein said location information field is transmitted from the station to the network at a time determined by the station.

15. The device according to claim 11, wherein said location information field is transmitted from the station to an access point (AP) on the network when the station is polled by the AP.

16. The device according to claim 11, wherein said location information field is transmitted from the station to an access point (AP) on the network when the AP sends a request to the station for location information.

17. A method for placing an emergency call by a station on a wireless local area network (WLAN), comprising the steps of:

placing the emergency call by the station;

determining whether the station is capable of operating on a cellular network;

continuing the emergency call on the cellular network if the station is capable of operating on the cellular network;

determining whether the emergency call was completed on the cellular network; and

continuing the emergency call on the WLAN if the emergency call was not completed on the cellular network.

18. A method for locating a user placing an emergency call from a station on a wireless local area network, comprising the steps of:

placing the emergency call on the station; and

transmitting emergency signal frames from the station for a predetermined period of time, whereby the emergency signal frames can be received by an emergency worker to locate the user.

19. A method for locating a user placing an emergency call from a station on a wireless local area network, comprising the steps of:

placing the emergency call on the station;

transmitting emergency signal frames from the station;

receiving the emergency signal frames by an emergency worker;

determining whether the emergency worker is within a predetermined range of the user; and

establishing a direct connection between the user and the emergency worker when the emergency worker is within the predetermined range.

20. A method for supporting an emergency call in a wireless local area network (WLAN), comprising the steps of:

placing an emergency call by a station on the WLAN;

receiving the emergency call by an access point (AP) on the WLAN;

determining if the station has sufficient capabilities to complete the emergency call; and

having the AP act as a proxy for the station if the station does not have sufficient capabilities to complete the emergency call.

21. The method according to claim 20, further comprising the step of:

adding location information to the emergency call by the AP.

22. The method according to claim 20, further comprising the step of:

monitoring traffic on the WLAN by the AP, whereby the AP learns the capability information of stations on the WLAN such that the AP can act as a proxy for a station.

23. A method for maintaining location information at an access point (AP) for a station in a wireless local area network, comprising the steps of:

receiving location information from the station at the AP; and

storing the location information at the AP.

24. A method for maintaining location information at an access point (AP) for a station in a wireless local area network, comprising the steps of:

polling the station by the AP to receive location information;

reporting location information from the station to the AP; and

storing the location information at the AP.

25. The method according to claim 24, wherein the polling step is performed periodically.

26. A method for placing an emergency call on a wireless local area network, comprising the steps of:

sending a ready to send (RTS) frame from a station making the emergency call to an access point (AP), the RTS frame containing an indicator that the station is making an emergency call;

receiving the RTS frame at the AP;

backing off non-emergency stations, whereby the station making the emergency call can access the network prior to the non-emergency stations.

27. The method according to claim 26, wherein the backing off step includes having the station making the emergency call wait for a shorter period of time than non-emergency stations before attempting to access the network.

28. The method according to claim 26, wherein the backing off step includes having non-emergency stations wait for a longer period of time than the station making the emergency call before attempting to access the network.