Mobile communications system and connection control method

• US 20010014607A1
• Filed: 12/27/2000
• Published: 08/16/2001
• Est. Priority Date: 12/27/1999
• Status: Abandoned Application

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Furukawa, Hiroshi, Ushirokawa, Akihisa
• Application Number:
  US09/748,978
• Publication Number:
  US 20010014607A1
• Time in Patent Office: Days
• US Class Current: 455/436
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 36/185 using make before break

Abstract

A mobile communications system allowing high-speed setup and release of connection is disclosed. A primary group of base stations and a secondary group included in the primary group are set and a base station included in the secondary group is connected to a mobile station by a corresponding individual wireless link. Further, two common control channels PCCCH and SCCCH are provided to transfer control information and the PCCCH has a shorter control period. The setup control is performed only for a limited number of individual wireless links between the mobile station and the secondary group of base stations.

Claims

1. A mobile communications system allowing diversity handover control of a mobile station among a plurality of base stations which are controlled by a base-station control station, comprising:

a first set of base stations which are allowed to set up respective ones of individual wireless channels to the mobile station; and

a second set of base stations including a subset of the first set,

wherein a base station included in the first set is connected to the base-station control station by a corresponding wired link to exchange information associated with the mobile station, and a base station included in the second set is connected to the mobile station by a corresponding individual wireless link.

2. The mobile communications system according to

claim 1

, wherein the second set is a subset of the first set.

3. The mobile communications system according to

claim 1

, wherein the first set is updated at intervals of a first time period and the second set is update at intervals of a second time period, wherein the second time period is shorter than the first time period.

4. The mobile communications system according to

claim 2

, wherein the first set is updated at intervals of a first time period and the second set is update at intervals of a second time period, wherein the second time period is shorter than the first time period.

5. The mobile communications system according to

claim 1

, wherein

a primary common control channel (PCCCH) is used to transfer at least control information between the mobile station and each base station included in the first set;

and

a secondary common control channel (SCCCH) is used to transfer at least control information between the mobile station and the base-station control station.

6. The mobile communications system according to

claim 4

, wherein

a primary common control channel (PCCCH) is used to transfer at least control information between the mobile station and each base station included in the first set;

and

a secondary common control channel (SCCCH) is used to transfer at least control information between the mobile station and the base-station control station.

7. The mobile communications system according to

claim 5

, wherein the base-station control station controls each base station included in the first set by

receiving information from a base station through the SCCCH;

determining whether the base station is included in the first set, based on the information;

when it is determined that the base station is included in the first set, setting up a control channel for exchanging control information with the base station through the SCCCH;

determining whether an information channel is set up, based on control information on the control channel; and

when it is determined that an information channel is set up, setting up the information channel to the base station.

8. The mobile communications system according to

claim 5

, wherein a base station included in the first set controls a corresponding individual wireless link to the mobile station by

transmitting a pilot signal to a mobile station located in a cell thereof;

receiving a pilot response signal from the mobile station;

determining whether the base station is changed from the first set to the second set, based on the pilot response signal;

when it is determined that the base station is changed from the first set to the second set, activating the corresponding individual wireless link through the PCCCH; and

when it is determined that the base station is changed from the second set to the first set, inactivating the corresponding individual wireless link through the PCCCH.

9. The mobile communications system according to

claim 5

, wherein the mobile station controls setup of the second set by

exchanging a control signal with the base-station control station through the SCCCH in one of the cases where the mobile station is connected to a new base station and where the mobile station sets up and release a connection to a base station included in the first set;

determining a base station as a member of the second set based on quality of a pilot signal received from the base station; and

sending a control instruction to the selected base station through the PCCCH to set up an individual wireless link to the selected base station.

10. The mobile communications system according to

claim 8

, wherein the mobile station controls setup of the second set by

exchanging a control signal with the base-station control station through the SCCCH in one of the cases where the mobile station is connected to a new base station and where the mobile station sets up and release a connection to a base station included in the first set;

determining a base station as a member of the second set based on quality of a pilot signal received from the base station; and

sending a control instruction to the selected base station through the PCCCH to set up an individual wireless link to the selected base station.

11. The mobile communications system according to

claim 9

, wherein the mobile station determines the base station as a member of the second set when a quality value of a pilot signal received from the base station is not smaller than a predetermined value.

12. The mobile communications system according to

claim 9

, wherein the mobile station determines the base station as a member of the second set by

selecting a plurality of base stations from the first set, wherein each of the selected base stations provides the mobile station with a reception quality value of a pilot signal received from a selected base station, the reception quality value being not smaller than a predetermined level;

and

selecting a predetermined number of base stations from the selected base stations to determine each of the predetermined number of base stations as a member of the second set.

13. The mobile communications system according to

claim 9

, wherein the mobile station determines the base station as a member of the second set by

finding a maximum reception quality value among reception quality values of pilot signals received from respective ones of the base stations;

and

determining the base station as a member of the second set when a reception quality value of a pilot signal received from the base station is not smaller than a value obtained by subtracting a predetermined value from the maximum reception quality value.

14. A connection control method for use in a mobile communications system allowing diversity handover control of a mobile station among a plurality of base stations, which are controlled by a base-station control station provided within a switching network, the connection control method comprising the steps of:

setting a first set of base stations which are allowed to set up respective ones of individual wireless channels to the mobile station, wherein a base station included in the first set is connected to the base-station control station by a corresponding wired link to exchange information associated with the mobile station;

providing a primary common control channel (PCCCH) used to transfer at least control information between the mobile station and each base station included in the first set;

providing a secondary common control channel (SCCCH) used to transfer at least control information between the mobile station and the base-station control station, wherein the SCCCH is updated at intervals of a first time period and the PCCCH is update at intervals of a second time period, wherein the second time period is shorter than the first time period; and

setting a second set of base stations, which is a subset of the first set, wherein a base station included in the second set is connected to the mobile station through a corresponding individual wireless link that is set up by transferring a control instruction through the PCCCH.

15. The connection control method according to

claim 14

, wherein the PCCCH is terminated at the first set and the SCCCH is terminated at the base-station control station.

16. The connection control method according to

claim 14

, wherein the PCCCH is a wireless channel and the SCCCH is a combination of a wireless channel from the mobile station to the first set and a wired channel from the first set to the base-station control station.

17. The connection control method according to

claim 14

, wherein information associated with setup of the second set is not transferred on a wired link between the base-station control station and each of base stations included in the first set but in the second set.

18. The connection control method according to claim 14, further comprising the steps of:

at the base-station control station,

receiving information from a base station through the SCCCH;

determining whether the base station is included in the first set, based on the information;

when it is determined that the base station is included in the first set, setting up a control channel for exchanging control information with the base station through the SCCCH;

determining whether an information channel is set up, based on control information on the control channel; and

when it is determined that an information channel is set up, setting up the information channel to the base station.

19. The connection control method according to

claim 14

, further comprising the steps of:

at a base station included in the first set,

transmitting a pilot signal to a mobile station located in a cell thereof;

receiving a pilot response signal from the mobile station;

determining whether the base station is changed from the first set to the second set, based on the pilot response signal;

when it is determined that the base station is changed from the first set to the second set, activating the corresponding individual wireless link through the PCCCH; and

when it is determined that the base station is changed from the second set to the first set, inactivating the corresponding individual wireless link through the PCCCH.

20. The connection control method according to

claim 14

, further comprising the steps of:

at the mobile station,

a) exchanging a control signal with the base-station control station through the SCCCH in one of the cases where the mobile station is connected to a new base station and where the mobile station sets up and release a connection to a base station included in the first set;

b) determining a base station as a member of the second set based on quality of a pilot signal received from the base station; and

c) sending a control instruction to the selected base station through the PCCCH to set up an individual wireless link to the selected base station.

21. The connection control method according to

claim 20

, wherein the step (b) comprises the step of:

determining the base station as a member of the second set when a quality value of a pilot signal received from the base station is not smaller than a predetermined value.

22. The connection control method according to

claim 20

, wherein the step (b) comprises the step of:

selecting a plurality of base stations from the first set, wherein each of the selected base stations provides the mobile station with a reception quality value of a pilot signal received from a selected base station, the reception quality value being not smaller than a predetermined level; and

selecting a predetermined number of base stations from the selected base stations to determine each of the predetermined number of base stations as a member of the second set.

23. The connection control method according to

claim 20

, wherein the step (b) comprises the step of:

finding a maximum reception quality value among reception quality values of pilot signals received from respective ones of the base stations; and

determining the base station as a member of the second set when a reception quality value of a pilot signal received from the base station is not smaller than a value obtained by subtracting a predetermined value from the maximum reception quality value.