System and method for ranging for a fast handover in a mobile communication system

1. A method for assigning ranging codes in an orthogonal frequency division multiplexing (OFDM)/orthogonal frequency division multiple access (OFDMA) communication system, the method comprising the steps of:

classifying rangings between a base station and a mobile subscriber station (MSS) of the OFDM/OFDMA communication system into an initial ranging, a periodic ranging, a bandwidth request ranging, and a handover ranging;

creating a first number of ranging codes used for the rangings; and

assigning a second number of ranging codes selected from the first number of ranging codes as handover ranging codes used for the handover ranging.

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

assigning a third number of ranging codes selected from the first number of ranging codes, except for the handover ranging codes, as initial ranging codes used for the initial ranging;

assigning a fourth number of ranging codes selected from the first number of ranging codes, except for the handover ranging codes and the initial ranging codes, as periodic ranging codes used for the periodic ranging; and

assigning a fifth number of ranging codes selected from the first number of ranging codes, except for the handover ranging codes, the initial ranging codes, and the periodic ranging codes, as bandwidth request ranging codes used for the bandwidth request ranging.

3. The method as claimed in claim 1 , wherein the handover ranging is an initial ranging used for a handover when the handover occurs in the MSS.

4. A method for performing a handover ranging when a mobile subscriber station (MSS) that is serviced by a serving base station is handed over to a target base station in an orthogonal frequency division multiplexing (OFDM)/orthogonal frequency division multiple access (OFDMA) communication system, the method comprising the steps of:

receiving information including handover ranging codes for handover ranging from the target base station; and

performing the handover ranging with handover ranging codes to the target base station.

5. The method as claimed in claim 4 , wherein the information includes initial ranging codes for an initial ranging, periodic ranging codes for a periodic ranging, bandwidth request ranging codes for a bandwidth request ranging, and handover ranging codes for the handover ranging.

6. The method as claimed in claim 4 , wherein the handover ranging is an initial ranging used for a handover when the handover occurs in the MSS.

7. A method for assigning ranging slots in an orthogonal frequency division multiplexing (OFDM)/orthogonal frequency division multiple access (OFDMA) scheme communication system, the method comprising the steps of:

classifying rangings between a base station and a mobile subscriber station (MSS) in the OFDM/OFDMA communication system into an initial ranging, a periodic ranging, a bandwidth request ranging, and a handover ranging;

creating a first number of ranging slots used for the rangings; and

assigning a second number of ranging slots selected from the first number of ranging slots as handover ranging slots used for the handover ranging.

8. The method as claimed in claim 7 , further comprising the steps of:

assigning a third number of ranging slots selected from the first number of ranging slots, except for the handover ranging slots, as initial ranging slots used for the initial ranging;

assigning a fourth number of ranging slots selected from the first number of ranging slots, except for the handover ranging slots and the initial ranging slots, as periodic ranging slots used for the periodic ranging; and

assigning a fifth number of ranging slots selected from the first number of ranging slots, except for the handover ranging slots, the initial ranging slots, and the periodic ranging slots, as bandwidth request ranging slots used for the bandwidth request ranging.

9. The method as claimed in claim 7 , wherein the handover ranging is an initial ranging used for a handover when the handover occurs in the MSS.

10. A system for performing a handover ranging during a handover in an orthogonal frequency division multiplexing (OFDM)/orthogonal frequency division multiple access (OFDMA) communication system, the system comprising:

a target base station for classifying rangings of the OFDM/OFDMA communication system into an initial ranging, a periodic ranging, a bandwidth request ranging, and a handover ranging, creating a first number of ranging codes used for the rangings, assigning a second number of ranging codes selected from the first number of ranging codes as handover ranging codes used for the handover ranging, and transmitting information including the assigned handover ranging codes; and

a mobile subscriber station (MSS) for receiving the information from the target base station, and performing the handover ranging with handover ranging codes to the target base station.

11. The system as claimed in claim 10 , wherein the target base station assigns a third number of ranging codes selected from the first number of ranging codes, except for the handover ranging codes, as initial ranging codes used for the initial ranging, assigns a fourth number of ranging codes selected from the first number of ranging codes, except for the handover ranging codes and the initial ranging codes, as periodic ranging codes used for the periodic ranging, assigns a fifth number of ranging codes selected from the first number of ranging codes, except for the handover ranging codes, the initial ranging codes, and the periodic ranging codes, as bandwidth request ranging codes used for the bandwidth request ranging, and transmits the information including the initial ranging codes, the periodic ranging codes, and the bandwidth request ranging codes to the MSS.

12. The system as claimed in claim 10 , wherein the handover ranging is an initial ranging used for a handover when the handover occurs in the MSS.

13. A method for performing a handover ranging when a mobile subscriber station (MSS) that is serviced by a serving base station is handed over to a target base station in an orthogonal frequency division multiplexing (OFDM)/orthogonal frequency division multiple access (OFDMA) communication system, the method comprising the steps of:

classifying, by the target base station, rangings between the target base station and the MSS of the OFDMIOFDMA communication system into an initial ranging, a periodic ranging, a bandwidth request ranging, and a handover ranging;

creating a first number of ranging codes used for the rangings;

assigning a second number of ranging codes selected from the first number of ranging codes as handover ranging codes used for the handover ranging;

transmitting information including the assigned handover ranging codes;

receiving, by the MSS, the information from the target base station; and

performing the handover ranging with handover ranging codes to the target base station.

14. The method as claimed in claim 13 , further comprising the steps of:

assigning, by the target base station, a third number of ranging codes selected from the first number of ranging codes, except for the handover ranging codes, as initial ranging codes used for the initial ranging;

assigning a fourth number of ranging codes selected from the first number of ranging codes, except for the handover ranging codes and the initial ranging codes, as periodic ranging codes used for the periodic ranging;

assigning a fifth number of ranging codes selected from the first number of ranging codes, except for the handover ranging codes, the initial ranging codes, and the periodic ranging codes, as bandwidth request ranging codes used for the bandwidth request ranging; and

transmitting the information including the initial ranging codes, periodic ranging codes, and bandwidth request ranging codes to the MSS.

15. The method as claimed in claim 13 , wherein the handover ranging is an initial ranging used for a handover when the handover occurs in the MSS.

16. A method for performing a handover ranging when a mobile subscriber station (MSS) that is serviced by a serving base station is handed over to a target base station in an orthogonal frequency division multiplexing (OFDM)/orthogonal frequency division multiple access (OFDMA) communication system, the method comprising the steps of:

receiving information including handover ranging slots for the handover ranging from the target base station; and

performing the handover ranging with the handover ranging slots to the target base station.

17. The method as claimed in claim 16 , wherein the information includes initial ranging slots for an initial ranging, periodic ranging slots for a periodic ranging, bandwidth request ranging slots for a bandwidth request ranging, and the handover ranging slots for the handover ranging.

18. The method as claimed in claim 16 , wherein the handover ranging is an initial ranging used for a handover when the handover occurs in the MSS.

19. A method for performing a handover ranging when a mobile subscriber station (MSS) that is serviced by a serving base station is handed over to a target base station in an orthogonal frequency division multiplexing (OFDM)/orthogonal frequency division multiple access (OFDMA) communication system, the method comprising the steps of:

classifying, by the target base station, rangings between the target base station and the MSS of the OFDM/OFDMA communication system into an initial ranging, a periodic ranging, a bandwidth request ranging, and a handover ranging;

creating a first number of ranging slots used for the rangings;

assigning a second number of ranging slots selected from the first number of ranging slots as handover ranging slots used for the handover ranging;

transmitting information including the assigned handover ranging slots;

receiving, by the MSS, the information from the target base station and

performing the handover ranging with the handover ranging slots to the target base station.

20. The method as claimed in claim 19 , further comprising the steps of:

assigning, by the target base station, a third number of ranging slots selected from the first number of ranging slots, except for the handover ranging slots, as initial ranging slots used for the initial ranging;

assigning a fourth number of ranging slots selected from the first number of ranging slots, except for the handover ranging slots and the initial ranging slots, as periodic ranging slots used for the periodic ranging;

assigning a fifth number of ranging slots selected from the first number of ranging slots, except for the handover ranging slots, the initial ranging slots, and the periodic ranging slots, as bandwidth request ranging slots used for the bandwidth request ranging; and

transmitting the information including the initial ranging slots, the periodic ranging slots, and the bandwidth request ranging slots to the MSS.

21. The method as claimed in claim 19 , wherein the handover ranging is an initial ranging used for a handover when the handover occurs in the MSS.

22. A system for performing a handover ranging during a handover in an orthogonal frequency division multiplexing (OFDM)/orthogonal frequency division multiple access (OFDMA) communication system, the system comprising:

a target base station for classifying rangings of the OFDM/OFDMA communication system into an initial ranging, a periodic ranging, a bandwidth request ranging, and a handover ranging, creating a first number of ranging slots used for the rangings, assigning a second number of ranging slots selected from the first number of ranging slots as handover ranging slots used for the handover ranging, and transmitting information including the assigned handover ranging slots, and

a mobile subscriber station (MSS) for receiving the information from the target base station, and performing the handover ranging with the handover ranging slots to the target base station.

23. The system as claimed in claim 22 , wherein the target base station assigns a third number of ranging slots selected from the first number of ranging slots, except for the handover ranging slots, as initial ranging slots used for the initial ranging, assigns a fourth number of ranging slots selected from the first number of ranging slots, except for the handover ranging slots and the initial ranging slots, as periodic ranging slots used for the periodic ranging, assigns a fifth number of ranging slots selected from the first number of ranging slots, except for the handover ranging slots, the initial ranging slots, and the periodic ranging slots, as bandwidth request ranging slots used for the bandwidth request ranging, and transmits the information including the initial ranging slots, the periodic ranging slots, and the bandwidth request ranging slots to the MSS.

24. The system as claimed in claim 22 , wherein the handover ranging is an initial ranging used for a handover when the handover occurs in the MSS.