System and method for performing a fast handover in a broadband wireless access communication system

• US 20050250498A1
• Filed: 05/09/2005
• Published: 11/10/2005
• Est. Priority Date: 05/07/2004
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Koo, Chang-Hoi, Lee, Sung-Jin, Son, Yeong-Moon, Kim, So-Hyun, Kang, Hyun-Jeong, Son, Jung-Je, Lim, Hyoung-Kyu
• Granted Patent: US 7,593,731 B2
• Time in Patent Office: Days
• US Class Current: 455/436
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 36/26 by agreed or negotiated communication parameters

Abstract

A broadband wireless access (BWA) communication system includes a mobile subscriber station (MSS), a serving base station (BS) with which the MSS performs communication, and a plurality of neighbor BSs. The serving BS transmits, to the MSS, a handover request message including information on at least one recommended BS to which the MSS can perform a handover, among the neighbor BSs, and indication information indicating a fast handover, and transmits, to each of the recommended BSs, a handover confirm message indicating that the MSS will perform the fast handover.

Claims

1. A method for performing a handover of a mobile subscriber station (MSS) by a serving base station (BS) in a broadband wireless access (BWA) communication system including the MSS, the serving BS, and a plurality of neighbor BSs, the method comprising the steps of:

detecting a need for a handover of the MSS;

determining which of the plurality of neighbor BSs can support a service that the MSS is currently receiving;

selecting at least one recommended BS capable of supporting the service that the MSS is currently receiving according to the determination result;

transmitting a handover request including information on the at least one recommended BS to the MSS;

transmitting, to each of the at least one recommended BS, a notification that the MSS will perform the handover; and

allocating, by each of the at least one recommended BS, a fast ranging resource for handover of the MSS.

2. The method of claim 1, further comprising the steps of:

receiving an authentication request for the MSS from a target BS determined by the MSS, among the each of the at least one recommended BS; and

transmitting a notification for ordering a release of a ranging resource allocated to the MSS, to other recommended BSs, excluding the target BS from the at least one recommended BS.

3. The method of claim 1, further comprising the steps of:

receiving information indicating completion of a handover process of the MSS from a target BS determined by the MSS, among the at least one recommended BS; and

transmitting a notification for ordering a release of a ranging resource allocated to the MSS, to other recommended BSs, excluding the target BS from the at least one recommended BS.

4. The method of claim 1, wherein the serving BS transmits, to the MSS, the handover request including information indicating fast handover.

5. The method of claim 1, wherein the serving BS receives a response to the handover request from the MSS, the response including an identifier (ID) of a particular target BS.

6. The method of claim 1, wherein the serving BS receives a response to the handover request from the MSS, the response including a predefined value.

7. The method of claim 1, wherein the serving BS provides the plurality of neighbor BSs with information on a service that the MSS is receiving and operational context information, using a backbone message.

8. A method for performing handover by a mobile subscriber station (MSS) in a broadband wireless access (BWA) communication system including the MSS, a serving base station (BS), and a plurality of neighbor BSs, the method comprising the steps of:

receiving, from the serving BS, a handover request including information on recommended BSs to which the MSS can perform handover;

determining a target BS to which the MSS desires to perform handover, among the recommended BSs; and

performing handover to the target BS using a fast ranging resource that the target BS provides for fast handover of the MSS.

9. The method of claim 8, wherein the step of determining the target BS comprises the steps of:

detecting a BS of which channel quality is higher than or equal to a predetermined threshold in a process of measuring channel quality for each of the recommended BSs;

determining the detected BS as the target BS; and

stopping the channel quality measurement on the other recommended BSs.

10. The method of claim 9, wherein the channel quality measurement is achieved by measuring a carrier-to-interference and noise ratio (CINR).

11. The method of claim 8, wherein the step of determining the target BS comprises the steps of:

measuring channel quality for each of the recommended BSs; and

determining a BS having the highest channel quality as the target BS.

12. The method of claim 11, wherein the channel quality measurement is achieved by measuring a carrier-to-interference and noise ratio (CINR).

13. The method of claim 8, further comprising the step of receiving a fast ranging resource from each of the recommended BSs.

14. The method of claim 8, further comprising the step of transmitting to the serving BS a notification indicating that the MSS will perform handover to one of BSs recommended by the serving BS upon receiving a handover request from the serving BS.

15. A method for performing a handover in a broadband wireless access (BWA) communication system including a mobile subscriber station (MSS), a serving base station (BS), and a plurality of neighbor BSs, the method comprising the steps of:

detecting a need for a handover of the MSS;

determining, by the serving BS, which of the plurality of neighbor BSs can support a service that the MSS is currently receiving;

determining, by the serving BS, at least one recommended BS capable of supporting the current service of the MSS according to the determination result;

transmitting, to the MSS, a handover request including information on the at least one recommended BS;

transmitting, by the serving BS, a notification indicating that the MSS will perform handover, to each of the at least one recommended BS;

controlling each of the at least one recommended BS to allocate a fast raging resource for fast handover of the MSS;

receiving, by the MSS, the handover request including information on the at least one recommended BS to which the MSS can perform handover, from the serving BS;

determining, by the MSS, a target BS to which the MSS desires to perform handover, among the at least one recommended BS; and

performing a handover to the target BS using a fast ranging resource that the target BS provides for the handover.

16. The method of claim 15, further comprising the steps of:

receiving, by the serving BS, an authentication request for the MSS from the target BS determined by the MSS, among the at least one recommended BS; and

transmitting a notification for ordering a release of a raging resource allocated to the MSS, to other recommended BSs, excluding the target BS from the at least one recommended BS.

17. The method of claim 15, further comprising the steps of:

receiving, by the serving BS, information indicating completion of the handover process of the MSS from the target BS determined by the MSS, among the at least one recommended BS; and

transmitting a notification for ordering a release of a raging resource allocated to the MSS, to other recommended BSs, excluding the target BS from the at least one recommended BS.

18. The method of claim 15, wherein the serving BS transmits, to the MSS, a handover request including information indicating the fast handover.

19. The method of claim 15, wherein the MSS transmits a response including an identifier (ID) of a particular target BS to the serving BS in response to the handover request.

20. The method of claim 15, wherein the MSS transmits a response including a value predefined between the MSS and the serving BS to the serving BS in response to the handover request.

21. The method of claim 15, wherein the serving BS provides the plurality of neighbor BSs with information on the service that the MSS is receiving and operational context information, using a backbone message.

22. A handover system in a broadband wireless access (BWA) communication system, the system comprising:

a mobile subscriber station (MSS);

a serving base station (BS); and

a plurality of neighbor BSs being different from the serving BS;

wherein the serving BS, upon detecting a need for handover of the MSS, determines which of the plurality of neighbor BSs can support a service that the MSS is currently receiving, selects at least one recommended BS capable of supporting the current service of the MSS according to the determination result, transmits a handover request including information on the recommended BSs to the MSS, and transmits a notification indicating that the MSS will perform handover, to each of the at least one recommended BS in order to control each of the at least one recommended BS to allocate a fast ranging resource for handover of the MSS; and

wherein the MSS receives, from the serving BS, the handover request including information on recommended BSs to the MSS can perform handover, determines a target BS to which the MSS desires to perform handover, among the recommended BSs, and performs a handover to the target BS using a fast ranging resource that the target BS provides for the handover.

23. The handover system of claim 22, wherein upon receiving an authentication request for the MSS from the target BS, the serving BS transmits a notification for ordering a release of a ranging resource allocated to the MSS, to other recommended BSs, excluding the target BS from the at least one recommended BS.

24. The handover system of claim 22, wherein upon receiving information indicating completion of a handover process of the MS from the target BS, the serving BS transmits a notification for ordering a release of a ranging resource allocated to the MSS, to other recommended BSs, excluding the target BS from the at least one recommended BS.

25. The handover system of claim 22, wherein the serving BS transmits a handover request including information indicating fast handover.

26. The handover system of claim 22, wherein the MSS transmits, to the serving BS, a notification indicating that the MSS will perform the handover to a particular target BS among the at least one BS recommended by the serving BS in response to the handover request from the serving BS.

27. The handover system of claim 22, wherein upon detecting a BS of which channel quality is higher than or equal to a predetermined threshold in a process of measuring channel quality for each of the recommended BSs, the MSS determines the detected BS as a target BS and stops the channel quality measurement on other of the at least one recommended BS.

28. The handover system of claim 27, wherein the channel quality measurement is achieved by measuring a carrier-to-interference and noise ratio (CINR).

29. The handover system of claim 22, wherein the MSS measures channel quality for each of the recommended BSs and determines a BS having the highest channel quality as a target BS.

30. The handover system of claim 29, wherein the channel quality measurement is achieved by measuring a carrier-to-interference and noise ratio (CINR).

31. The handover system of claim 22, wherein the MSS transmits a response including an identifier (ID) of a particular target BS to the serving BS in response to a handover request.

32. The handover system of claim 22, wherein the MSS transmits a response including a value predefined between the MSS and a serving BS to the serving BS in response to the handover request.

33. The handover system of claim 22, wherein the serving BS provides the plurality of neighbor BSs with information on a service that the MSS is receiving and operational context information, using a backbone message.

34. A method for performing a handover of a mobile subscriber station (MSS) by a serving base station (BS) in a broadband wireless access (BWA) communication system including the MSS, the serving BS, and a plurality of neighbor BSs, the method comprising the steps of:

transmitting, to the MSS, a handover request message including information on at least one recommended BS to which the MSS can perform handover, among the neighbor BSs, and indication information indicating that the serving BS supports a network assisted handover; and

transmitting, to each of the at least one recommended BS, a handover confirm message indicating that the MSS will perform the network assisted handover.

35. The method of claim 34, further comprising the steps of:

receiving, by the serving BS, an authentication request for the MSS from a target BS determined by the MSS handover among the at least one recommended BS; and

transmitting a notification for ordering a release of a ranging resource allocated to the MSS, to other recommended BSs, excluding the target BS from the at least one recommended BS.

36. The method of claim 34, further comprising the steps of receiving, by the serving BS, information indicating a completion of a handover process of the MSS from a target BS determined by the MSS among the recommended BSs.

37. The method of claim 36, further comprising the step of transmitting a notification for ordering a release of a ranging resource allocated to the MSS, to other recommended BSs, excluding the target BS from the at least one recommended BS.

38. The method of claim 34, wherein the network assisted handover represents the MSS may perform a handover to a selected target BS among the recommended BSs without notifying the serving BS of the selected target BS.

39. A method for performing a handover by a mobile subscriber station (MSS) in a broadband wireless access (BWA) communication system including the MSS, a serving base station (BS), and a plurality of neighbor BSs, the method comprising the steps of:

receiving, from the serving BS, a handover request message including information on at least one recommended BS to which the MSS can perform handover, among the neighbor BSs, and indication information indicating that the serving BS supports a network assisted handover; and

transmitting, to the serving BS, a handover indication message not including information of a target BS to which the MSS desires to perform handover.

40. The method of claim 39, further comprising the steps of:

receiving, from the target BS, a fast ranging resource for handover of the MSS;

transmitting, to the target BS, a ranging request message; and

receiving, from the target BS, the ranging response message.

41. A method for performing a handover in a broadband wireless access (BWA) communication system including a mobile subscriber station (MSS), a serving base station (BS), and a plurality of neighbor BSs, the method comprising the steps of:

transmitting to the MSS, by the serving BS, a handover request message including information on at least one recommended BS to which the MSS can perform a fast handover among the plurality of neighbor BSs, and indication information for ordering the fast handover to a target BS determined by the MSS among the at least one recommended BS;

transmitting, by the MSS, information on the determined target BS to the serving BS; and

performing the fast handover to the target BS.

42. The method of claim 41, wherein the MSS performs the fast handover without transmitting the information on the determined target BS to the serving BS.