Mobile communication system, network and mobile station

• US 6,157,837 A
• Filed: 01/21/1997
• Issued: 12/05/2000
• Est. Priority Date: 01/23/1996
• Status: Expired due to Term

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: NTT Mobile Communications Network Inc. (Nippon Telegraph and Telephone Corporation)
• Inventors: Sugiyama, Kazuo, Sasada, Koji, Okajima, Ichiro, Kato, Yasuhiro, Maebara, Akihiro
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): Vuong, Quochien B.
• Application Number:
  US08/786,480
• Time in Patent Office: 1,414 Days
• Field of Search: 455/422, 455/436, 455/437, 455/438, 455/442, 455/575, 455/525, 455/439, 455/512, 455/513, 455/62, 455/509, 370/331, 370/332
• US Class Current: 455/437
• CPC Class Codes: H04W 36/0061 of neighbour cell information

Abstract

An object of the present invention is to reduce the control time required when a channel handover is performed in a mobile communication system. The conventional system has such shortcomings that a long time is required for re-designating a channel when a channel handover procedure results in failure. Particularly, in the common access type system, there is such a problem that since a channel handover is required to be performed several times during a channel handover procedure, an extra time is required for performing the handover procedure. The present invention has a plurality of base stations for covering the service area, and a mobile station for performing a communication with the base stations through radio channels. Here, the present invention is characterized in that the base stations notify the mobile station of a plurality of candidates when the mobile station performs a handover procedure, thereby improving the problem inherent in the conventional system that a single candidate is notified when a channel handover procedure is performed. Therefore, the present invention makes it possible to change the channel to the next candidate channel at high speed when the previous channel handover procedure results in failure.

Claims

1. A method for determining a next radio communication channel for a mobile station to maintain a continuing communication with a fixed network, the fixed network including a plurality of base stations each forming a radio zone respectively in a mobile communication system, comprising the steps of:

designating in the mobile station, at least one radio zone as a candidate(s) from among radio zones peripheral to a radio zone in which the mobile station is located;

transmitting information indicating the designated at least one candidate radio zone, from the mobile station to the fixed network;

selecting in the network, at least one radio zone from the designated candidate radio zones and at least one candidate channel for each selected one of the designated candidate radio zones;

transmitting information indicating a plurality of selected candidate channels, from the network to the mobile station; and

determining in the mobile station, the next channel from the plurality of selected candidate channels for continuing a communication between the mobile station and the network as the mobile station travels from one radio zone to another.

2. The method for changing a radio communication channel between a mobile station and a fixed network according to claim 1, wherein the information transmitted from the network includes for each selected candidate channel a corresponding radio zone for determining the next radio zone and the next channel.

3. The method for changing a radio communication channel between a mobile station and a fixed network according to claim 2, further comprising the step of arranging in the network the selected candidate channels and corresponding radio zones in order of priority.

4. The method for changing a radio communication channel between a mobile station and a fixed network according to claim 3, wherein the order of priority is based on signal level.

5. The method for changing a radio communication channel between a mobile station and a fixed network according to claim 3, wherein the order of priority is based on utilization level.

6. The method for changing a radio communication channel between a mobile station and a fixed network according to claim 3, wherein the step of determining in the mobile station the next radio zone and the next channel for continuing a communication, includes the step of attempting a connection to each of the selected candidate channels in sequence in order of priority until a successful connection is achieved.

7. A method for changing a radio communication channel between a mobile station and a fixed network, the fixed network including a plurality of base stations each forming a radio zone respectively in a mobile communication system, comprising the steps of:

designating in the mobile station, at least one radio zone as a candidate(s) for determining a next radio zone;

transmitting information indicating the designated at least one candidate radio zone, from the mobile station to a first base station;

sending a signal from the first base station to at least one second base station forming the designated at least one candidate radio zone, the signal requesting a selection of at least one candidate channel for the designated at least one candidate radio zone;

selecting in each of the at least one second base station in response to the signal from the first base station, at least one candidate channel for determining a next channel;

sending information from each of the at least one second base station to the first base station identifying the selected at least one candidate channel;

transmitting information indicating a plurality of selected candidate channels, from the first base station to the mobile station; and

determining in the mobile station, the next radio zone and the next channel for continuing a communication on the bases of the information transmitted from the first base station indicating a plurality of selected candidate channels.

8. The method for changing a radio communication channel between a mobile station and a fixed network according to claim 7, wherein the information transmitted from the first base station includes for each selected candidate channel a corresponding radio zone for determining the next radio zone and the next channel.

9. The method for changing a radio communication channel between a mobile station and a fixed network according to claim 8, further comprising the step of arranging in the first base station the selected candidate channels and corresponding radio zones in order of priority.

10. The method for changing a radio communication channel between a mobile station and a fixed network according to claim 9, wherein the order of priority is based on signal level.

11. The method for changing a radio communication channel between a mobile station and a fixed network according to claim 9, wherein the order of priority is based on utilization level.

12. The method for changing a radio communication channel between a mobile station and a fixed network according to claim 9, wherein the step of determining in the mobile station the next radio zone and the next channel for continuing a communication, includes the step of attempting a connection to each of the selected candidate channels in sequence in order of priority until a successful connection is achieved.

13. The method for changing a radio communication channel between a mobile station and a fixed network according to claim 7, wherein said information indicating a plurality of selected candidate channels includes information indicating the priority among the selected candidate channels, and said mobile station decides the next channel on the basis of said information indicating priority.

14. A network which includes a plurality of base stations each forming a radio zone respectively and communicating with mobile stations over the air, comprising:

a receiver, receiving from a mobile station information which indicates at least one radio zone designated as a candidate(s) from among radio zones peripheral to a radio zone in which the mobile station is located;

a selector, selecting at least one radio zone from the designated candidate radio zones and at least one candidate channel for each selected one of the designated candidate radio zones; and

a transmitter, sending information to the mobile station indicating a plurality of candidate channels from which the mobile station is going to choose a next communication channel for continuing a communication with the mobile station as the mobile station travels from one radio zone to another.

15. A mobile station communicating over the air with a network which includes a plurality of base stations each forming a radio zone respectively, comprising:

a selector, selecting at least one radio zone designated as a candidate(s) from among radio zones peripheral to a radio zone in which the mobile station is located;

a receiver, receiving the information sent from the network indicating a plurality of candidate channels for determining a next communication channel, at least one candidate channel being selected for each radio zone selected in the network from the at least one candidate radio zone; and

a processor for determining the next communication channel from the plurality of candidate channels for continuing a communication with the network as the mobile station travels from one radio zone to another.

16. A network which includes a plurality of base stations each forming a radio zone respectively and communicating with mobile stations over the air, comprising:

a receiver in a first base station, receiving information sent by a mobile station which indicates at least one radio zone selected as a candidate(s) for determining a next radio zone;

a first transmitter in the first base station, sending a signal to at least one second base station forming the selected at least one radio zone which instructs each of the at least one second base station to select at least one candidate channel for a next channel;

a selector in each of the at least one second base station responsive to the signal transmitted by the first transmitter, selecting at least one candidate channel for determining the next channel;

a second transmitter in each of the at least one second base station, sending information indicating the at least one selected candidate channel to the first base station; and

a third transmitter in the first base station, sending information to the mobile station indicating a plurality of candidate channels for determining a next communication channel.

17. A mobile station communicating over the air with a network which includes a plurality of base stations each forming a radio zone respectively, comprising:

a selector, selecting at least one radio zone designated as a candidate(s) from among radio zones peripheral to a radio zone in which the mobile station is located;

a receiver, receiving information sent from a base station indicating a plurality of candidate channels for determining a next communication channel, at least one candidate channel being selected for each radio zone selected in the network from the at least one candidate radio zone; and

a processor for determining the next communication channel from the plurality of candidate channels for continuing a communication with the network as the mobile station travels from one radio zone to another.

18. A method for determining a next radio communication channel for a mobile station to maintain a continuing communication with a fixed network, the fixed network including a plurality of base stations each forming a radio zone respectively in a mobile communication system, the method comprising the steps of:

designating in the mobile station, at least one radio zone as a candidate(s) from among radio zones peripheral to a radio zone in which the mobile station is located;

transmitting information indicating the designated at least one candidate radio zone, from the mobile station to the fixed network;

selecting in the network, at least one radio zone from the designated candidate radio zones and at least one candidate channel for each selected one of the designated candidate radio zones;

transmitting information indicating a plurality of selected candidate channels, from the network to the mobile station; and

attempting in the mobile station a connection to each of the selected candidate channels in sequence until a successful connection is achieved in order to determine the next communication channel for continuing a communication between the mobile station and the network as the mobile station travels from one radio zone to another.

19. A mobile station communicating over the air with a network which includes a plurality of base stations each forming a radio zone respectively, comprising:

a selector, selecting at least one radio zone designated as a candidate(s) from among radio zones peripheral to a radio zone in which the mobile station is located;

a receiver, receiving information sent from the network indicating a plurality of candidate channels for determining a next communication channel, at least one candidate channel being selected for each radio zone selected in the network from the candidate radio zones; and

a processor for attempting a connection to each of the selected candidate channels in sequence until a successful connection is achieved in order to determine the next communication channel for continuing a communication with the network as the mobile station travels from one radio zone to another.

20. A mobile station communicating over the air with a network which includes a plurality of base stations each forming a radio zone respectively, comprising:

a selector, selecting at least one radio zone as a candidate(s) for determining a next radio zone among radio zones peripheral to the current radio zone in which the mobile station is located;

a receiver, receiving from the base station forming the current radio zone information indicating a plurality of candidate channels for determining a next communication channel, at least one candidate channel being selected for each radio zone selected in the network from the at least one candidate radio zone; and

a processor for attempting a connection to each of the selected candidate channels in sequence until a successful connection is achieved in order to determine the next communication channel from the plurality of candidate channels for continuing a communication with the network as the mobile station travels from one radio zone to another.