SYSTEM AND METHOD FOR PERFORMING HANDOVER IN A BROADBAND WIRELESS ACCESS COMMUNICATION SYSTEM

• US 20080159235A1
• Filed: 03/19/2008
• Published: 07/03/2008
• Est. Priority Date: 11/07/2003
• 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
• Granted Patent: US 8,077,673 B2
• Time in Patent Office: Days
• US Class Current: 370/332
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 36/26 by agreed or negotiated communication parameters

Abstract

Disclosed is a system and a method for controlling a handover of a mobile subscriber station in a broadband wireless access communication system. When serving base station determines to perform a handover of the mobile subscriber station, neighbor base stations to which the mobile subscriber station can be handed over, from among neighbor base stations of the mobile subscriber station, are determined based on a service quality level of service being currently provided to the mobile subscriber station. A handover request signal containing information related to the determined neighbor base station to which the mobile subscriber station can be handed over is transmitted to the mobile subscriber station. The serving base station receives from the mobile subscriber station in response to the request of the handover information about one neighbor base station to which the mobile subscriber station will be handed over, and informs the neighbor base station that the mobile subscriber station will be handed over to the neighbor base station.

Claims

1. A method for controlling a handover of a mobile subscriber station by a serving base station in a broadband wireless access communication system which includes the mobile subscriber station, the serving base station for providing service to the mobile subscriber station, and neighbor base stations neighboring the serving base station, the method comprising the steps of:

determining to perform a handover of the mobile subscriber station;

sending to the neighbor base stations a first information related to types of service provided from the serving base station to the mobile subscriber station after determining to perform the handover of the mobile subscriber station;

receiving from the neighbor base stations a second information related to types of service which can be provided by the neighbor base stations to the mobile subscriber station;

transmitting to the mobile subscriber station a handover request signal, which contains an third information determined by reference to the second information received from the neighbor base stations;

receiving from the mobile subscriber station a handover response signal indicating one neighbor base station selected by the mobile subscriber station among the neighbor base stations; and

sending a handover notification confirm signal to the selected neighbor base station;

wherein the third information signifies service level prediction information, which corresponds to any one service level prediction information from among a first service level prediction information is possible to provide all of services, a second service level prediction information is possible to provide a portion of the services and a third service level prediction information is not possible to provide any of the services in corresponding neighbor base station, and the mobile subscriber station performs a fast ranging with the selected neighbor base station using a ranging code.

2. The method as claimed in claim 1, wherein the step of determining to perform a handover of the mobile subscriber station is performed when a load for a current service is equal to or greater than a predetermined load.

3. The method as claimed in claim 1, wherein the second information received from the neighbor base stations includes information related to a quantity of service which can be provided by the neighbor base stations at a service quality level equal to that of the service currently being provided to the mobile subscriber station.

15. The method as claimed in claim 1, wherein the first information signifies required QoS (Quality of Services) information.

16. The method as claimed in claim 1, wherein the second information signifies QoS (Quality of Services) Estimated information.

17. The method as claimed in claim 1, wherein the first information signifies required QoS (Quality of Services) information.

18. The method as claimed in claim 1, wherein the second information signifies QoS (Quality of Services) Estimated information.

4. A method for controlling a handover of a mobile subscriber station in a broadband wireless access communication system which includes the mobile subscriber station, a serving base station for providing service to the mobile subscriber station, and neighbor base stations neighboring the serving base station, the method comprising the steps of:

receiving from the serving base station a handover request signal, which contains information received from the neighbor base stations;

selecting one neighbor base station from among the neighbor base stations based on the received information;

transmitting a handover start signal to the serving base station; and

performing by the mobile subscriber station a fast ranging with the selected neighbor base station using a ranging code,

wherein the information signifies service level prediction information which corresponds to any one service level prediction information from among a first service level prediction information is possible to provide all of services, a second service level prediction information is possible to provide a portion of the services and a third service level prediction information is not possible to provide any of the services in corresponding neighbor base station.

5. The method as claimed in claim 4, wherein the information received from the neighbor base stations includes information related to types of service which can be provided by the neighbor base stations.

6. The method as claimed in claim 4, wherein the step of selecting one neighbor base station is based on channel states of the respective neighbor base stations and service levels which can be provided by the respective neighbor base stations, with reference to the information related to the neighbor base stations received from the serving base station.

7. The method as claimed in claim 4, wherein the step of selecting one neighbor base station further comprises the steps of:

measuring CINRs (Carrier to Interference and Noise Ratios) of pilot channel signals received from the neighbor base stations which are determined as neighbor base stations to which the mobile subscriber station can be handed over;

selecting from among the neighbor base stations to which the mobile subscriber station can be handed over neighbor base stations from which a CINR exceeding a predetermined threshold CINR is measured; and

selecting one neighbor base station based on information related to services which can be provided by the selected neighbor base stations and the CINRs with respect to the selected neighbor base stations.

8. A system for controlling a handover of a mobile subscriber station by a serving base station in a broadband wireless access communication system which includes the mobile subscriber station, the serving base station for providing service to the mobile subscriber station, and neighbor base stations neighboring the serving base station, the system comprising:

a serving base station for determining to perform a handover of a mobile subscriber station, sending a first information related to service including types of service provided to the mobile subscriber station, receiving a second information related to types of service which can be provided by the neighbor base stations from the neighbor base stations, transmitting to the mobile subscriber station a handover request signal which contains an third information received from the neighbor base stations, receiving one neighbor base station selected by the mobile subscriber station from among the neighbor base stations, and confirming a handover notification to the selected neighbor base station; and

a mobile subscriber station for receiving from the serving base station a handover request signal containing the third information, selecting one neighbor base station from among the neighbor base stations based on the received the third information and transmitting the selected neighbor base station to the serving base station, transmitting a handover start signal to the serving base station, and performing the handover to the selected neighbor base station and a fast ranging with the selected neighbor base station using a ranging code,

wherein the third information signifies service level prediction information, which corresponds to any one service level prediction information from among a first service level prediction information is possible to provide all of services, a second service level prediction information is possible to provide a portion of the services and a third service level prediction information is not possible to provide any of the services in corresponding neighbor base station.

9. The system as claimed in claim 8, wherein the second information received from the neighbor base stations by the serving base station includes information related to a quantity of service which can be provided by the neighbor base stations at a service quality level at least equal to that of the service being currently provided to the mobile subscriber station,

wherein the third information indicates the quantity of service which can be provided by the neighbor base stations from among the services currently being provided to the mobile subscriber station.

10. The system as claimed in claim 8, wherein the serving base station determines to a handover the mobile subscriber station when a load for service being currently provided by the serving base station is equal to or greater than a predetermined load.

11. The system as claimed in claim 8, wherein the mobile subscriber station measures CINRs (Carrier to Interference and Noise Ratios) of pilot channel signals received from the neighbor base stations to detect channel states, and selects one neighbor base station to which the mobile subscriber station is handed over based on the CINRs measured with respect to the neighbor base stations to which the mobile subscriber station can be handed over and the service information.

12. The system as claimed in claim 8, wherein the mobile subscriber station measures CINRs (Carrier to Interference and Noise Ratios) of pilot channel signals received from the respective neighbor base stations to which the mobile subscriber station can be handed over, selects neighbor base stations from which a CINR exceeding a predetermined threshold CINR is measured from among the neighbor base stations to which the mobile subscriber station can be handed over, and then selects one neighbor base station based on information related to service which can be provided by the selected neighbor base stations and the CINRs with respect to the selected neighbor base stations.

13. A system for controlling a handover of a mobile subscriber station by a serving base station in a broadband wireless access communication system which includes the mobile subscriber station, the serving base station for providing service to the mobile subscriber station, and neighbor base stations neighboring the serving base station, the system comprising:

a serving base station for determining to perform a handover of a mobile subscriber station, sending a first information related to types of service provided to the mobile subscriber station, receiving a second information related to types of service which can be provided by the neighbor base stations from the neighbor base stations, transmitting to the mobile subscriber station a handover request signal which contains an third information received from the neighbor base stations, receiving a response signal from the mobile subscriber station in response to the handover request signal, selecting one neighbor base station based on the third information, and confirming a handover notification to the selected neighbor base station; and

a mobile subscriber station for receiving from the serving base station a handover request signal, which contains the second information received from the neighbor base stations, transmitting a response signal to the serving base station in response to the handover request signal, receiving from the serving base station the third information related to a neighbor base station to which the mobile subscriber station is handed over, transmitting a handover start signal to the serving base station, and performing the handover to a selected neighbor base station and a fast ranging with the selected neighbor base station using a ranging code,

wherein the third information signifies service level prediction information, which corresponds to any one service level prediction information from among a first service level prediction information is possible to provide all of services, a second service level prediction information is possible to provide a portion of the services and a third service level prediction information is not possible to provide any of the services in corresponding neighbor base station.

14. The system as claimed in claim 13, wherein the mobile subscriber station detects channel states by measuring CINRs (Carrier to Interference and Noise Ratios) of pilot channel signals received from the respective neighbor base stations to which the mobile subscriber station can be handed over, selects neighbor base stations from which a CINR exceeding a predetermined threshold CINR is measured from among the neighbor base stations to which the mobile subscriber station can be handed over, and then transmits to the serving base station in response to the handover request a response including CINRs with respect to the selected neighbor base stations to which the mobile subscriber station can be handed over.

19. The method as claimed in claim 14, wherein the first information signifies required QoS (Quality of Services) information.

20. The method as claimed in claim 14, wherein the second information signifies QoS (Quality of Services) Estimated information.

21. The method as claimed in claim 14, wherein the first information signifies required QoS (Quality of Services) information.

22. The method as claimed in claim 14, wherein the second information signifies QoS (Quality of Services) Estimated information.