Mobile communication system, radio switching method, mobile base station and mobile terminal

• US 20030235165A1
• Filed: 06/16/2003
• Published: 12/25/2003
• Est. Priority Date: 06/24/2002
• Status: Active Grant

• Current Assignee: Lenovo Innovations Ltd Hong Kong (Lenovo Group Ltd.)
• Original Assignee: NEC Corporation
• Inventors: Wang, Weizhong
• Granted Patent: US 7,852,808 B2
• Time in Patent Office: Days
• US Class Current: 370/331
• CPC Class Codes: H04W 36/12 Reselecting a serving backbone network switching or routing node
• CPC Class Codes: H04W 84/005 Moving wireless networks

Abstract

A mobile communication system, a radio switching method, a mobile base station and a mobile terminal in which the mobile terminal does not perform handover to a fixed base station while moving in/on a moving body to avert an adverse affect of variation of received field intensity on communication. Fixed base stations that are connected to a public telephone network are disposed along a traveling direction of a train. The train which a user who possesses a mobile terminal gets on is provided with a mobile base station capable of being connected to the fixed base stations. The mobile base station detects the mobile terminal entering into the communication area covered by the mobile base station and the train starting moving to the next station. Triggered by the two kinds of detection, the mobile base station takes over processes of handover to the fixed base station from the mobile terminal. While moving, the mobile base station performs handover to a next base station one after another. When the train approaches the next station, the mobile terminal performs handover to the fixed base station that covers the communication area around the station of arrival in behalf of the mobile base station.

Claims

1. A mobile communication system comprising:

a plurality of fixed base stations that are serially disposed along a moving direction of a moving body capable of high-speed moving and that are connected to a public telephone network;

a mobile terminal that is possessed by a user who gets on the moving body; and

a mobile base station that is capable of being connected to the plural fixed base stations and that is put in or on the moving body, wherein;

triggered by an entrance of the mobile terminal into a communication area of the mobile base station and by a start of the moving body, the mobile terminal performs handover from a fixed base station that has been connected to the mobile terminal to the mobile base station;

while the moving body is moving, the mobile base station sequentially performs handover to an adjacent fixed base station when the moving body enters into a communication area of the adjacent fixed base station; and

when the moving body approaches a stop, the mobile terminal performs handover from the mobile base station to a fixed base station that covers a communication area around the stop.

2. A mobile communication system as claimed in claim 1, wherein:

the moving body is a vehicle; and

the vehicle moves along a predetermined track where there is set at least one stop.

3. A mobile communication system as claimed in claim 1, wherein the mobile terminal is a mobile phone, personal handyphone system, or personal digital assistant capable of being connected to the public telephone network.

4. A radio switching method for sequentially performing handover to an adjacent fixed base station among a plurality of fixed base stations that covers respective communication areas divided into cells according to a move of a mobile terminal, comprising the steps of:

performing, by the mobile terminal in or on a moving body, handover from a fixed base station that covers a communication area where the moving body is located to a mobile base station that is put in or on the moving body, which is triggered by an entrance of the mobile terminal possessed by a user into a communication area of the mobile base station and when the moving body starts moving;

sequentially performing, by the mobile base station, handover to an adjacent fixed base station when the moving body enters into a communication area of the adjacent fixed base station while the moving body is moving; and

performing, by the mobile terminal, handover from the mobile base station to a fixed base station that covers a communication area around a stop when the moving body approaches the stop.

5. A radio switching method as claimed in claim 4, wherein:

the moving body is a vehicle; and

the vehicle moves along a predetermined track where there is set at least one stop.

6. A radio switching method as claimed in claim 4, wherein the mobile terminal is a mobile phone, personal handyphone system, or personal digital assistant capable of being connected to a public telephone network.

7. A mobile base station that is put in or on a moving body, comprising:

a first detecting means for detecting a mobile terminal entering into a communication area of the mobile base station;

a second detecting means for detecting the moving body which a user of the mobile terminal gets on starting moving; and

a control means for;

connecting to the mobile terminal and to a fixed base station that has been connected to the mobile terminal to continue communication between the mobile terminal and the fixed base station on the basis of the detection by the first and the second detecting means;

performing handover to an adjacent fixed base station when the moving body enters into a communication area of the adjacent fixed base station while the moving body is moving; and

getting the mobile terminal to perform handover to a fixed base station that covers a communication area around a stop when the moving body approaches the stop.

8. A mobile base station as claimed in claim 7, wherein, when the second detecting means detects the moving body starting moving, the control means informs a public telephone network of the detection by the second detecting means to direct the mobile terminal to perform handover to the mobile base station.

9. A mobile base station as claimed in claim 7, wherein the control means includes a third detecting means for detecting the moving body entering into a communication area of a fixed base station disposed adjacent to a currently connected fixed base station to notify a public telephone network of the detection by the third detecting means and to perform handover to the adjacent fixed base station according to a direction from the public telephone network in response to the notification.

10. A mobile base station as claimed in claim 7, wherein the control means includes a fourth detecting means for detecting the moving body approaching a next stop so that a public telephone network informs the mobile terminal of a direction to perform handover to a fixed base station that covers a communication area around the next stop on the basis of the detection by the fourth detecting means.

11. A mobile terminal capable of communicating with a fixed base station connected to a public telephone network by radio, including a communication means capable of communicating with a mobile base station put in or on a moving body when the mobile terminal is in or on or in the vicinity of the moving body, wherein:

the mobile terminal communicates with the mobile base station while the mobile terminal is moving in or on the moving body; and

the mobile terminal performs handover from the mobile base station to a fixed base station that covers a communication area around a stop when the moving body approaches the stop.