JP2002262326A - Handover system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a handover system for a system communication between road vehicle where a handover at a handover point can surely be executed by setting connection of an outgoing channel so that the connection is disconnected before the connection of an incoming channel. SOLUTION: In the handover system for the communication system between road and vehicle where next zone frequency information is provided in a control frame and the handover is started by out of synchronism, the handover is started before forced interruption of communication by a health function is executed by means of the setting of the electric field strength of incoming and outgoing frames, or frame reception sensitivity of a base station and a mobile station, or number of forward protection stages of a unique word of the outgoing frame, or number of permissible error bits so as to allow the outgoing frame synchronization to be more easily brought into out of synchronism than the incoming frame synchronization.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a handover system for realizing continuous communication in ITS road-to-vehicle communication.

[0002]

2. Description of the Related Art Conventionally, a road-to-vehicle communication system for starting a handover due to loss of synchronization has been known.

[0003]

In the handover method in such a road-to-vehicle communication system, when the health check of each channel is performed, if the electric field intensity of the downlink channel is stronger than the electric field intensity of the uplink, the handover zone is Even if the uplink channel becomes normal, there is a problem that an error is detected in the health check because the handover does not start.

[0004] In order to solve the above-mentioned problems, the present invention is to ensure that the handover at the handover point is performed by setting the connection of the downlink channel to be disconnected before the connection of the uplink channel. It is an object of the present invention to provide a handover method in a road-to-vehicle communication method that can perform the following.

[0005]

In order to achieve the above object, the present invention provides a road-to-vehicle communication system which has next zone frequency information in a control frame and starts handover due to loss of synchronization. In the handover method, the setting of the electric field strength of the upstream frame and the downstream frame, or the frame reception sensitivity of the base station and the mobile station, or the setting of the number of forward protection stages of the unique word of the downstream frame, or the allowable number of error bits thereof, By making synchronization easier to lose than upstream frame synchronization,
The handover is started before the forced disconnection of communication by the health check function is executed.

[0006]

Embodiments of the present invention shown in the drawings will be described. FIG. 1 shows a plurality of wireless zones 1, 2,.
3 shows a road-to-vehicle communication device that constitutes a service area by linking the three communication devices. In such a road-to-vehicle communication device,
The mobile station 4 as shown in FIG.
In the case of handover, the next zone (uplink frame) is set using one of the next zone frequencies in the downlink control frame 7 as shown in FIG. Send.

At this time, in the next zone frequency region in the downlink control frame 5 shown in FIG. 3, a candidate for the next zone frequency which is usually downstream is set. Here, for example, when the electric field strength of the downlink frame 5 is stronger than the uplink electric field strength, if a health check is performed between the base station and the mobile station as shown in FIG. The line is cut off, and the line is forcibly disconnected due to the timeout of the health check.

For this purpose, the electric field strength of the upstream frame 6 is
In the handover area, the downlink is cut off earlier than the uplink and the line is cut off by a method such as making the downlink field strength stronger or the reception sensitivity of the downlink frame 5 higher than the reception sensitivity of the uplink frame 6. Handover can be started without the need.

[0009]

As described above, the present invention provides a method of setting the electric field strength of the upstream frame and the downstream frame, or the frame reception sensitivity of the base station and the mobile station, or the number of forward protection stages of the unique word of the downstream frame, or the like. By setting the allowable number of error bits, the downlink frame synchronization is easily deviated from the uplink frame synchronization, so that the handover is started before the forcible disconnection of the communication by the health check function is executed. There is an effect that can be performed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an overall configuration of an embodiment of the present invention.

FIG. 2 is an operation explanatory view of the above.

FIG. 3 is an explanatory diagram of the transmission / reception.

FIG. 4 is an explanatory diagram of the health check.

[Explanation of symbols]

 1 wireless zone 2 wireless zone 3 wireless zone 4 mobile station 5 downlink frame 6 uplink frame 7 control frame

Claims (1)

[Claims] In a road-to-vehicle communication system having a next frame frequency information in a control frame and starting a handover due to loss of synchronization, setting of electric field strength of an uplink frame and a downlink frame, or frame reception of a base station and a mobile station By setting the sensitivity or the number of forward protection stages of the unique word of the downstream frame, or the allowable number of error bits thereof, forcibly disconnecting the communication by the health check function is performed by making the downstream frame synchronization easier than the upstream frame synchronization. A handover method wherein a handover is started beforehand.