JP2000165930A - Radio communication network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication system which can freely and efficiently execute communication without interposing a centralized control station between mobile objects. SOLUTION: Mobile objects loading plural radio communication terminal units are divided into plural groups 1-3 and terminal units 1-1, 2-1 and 3-1 in at least one mobile object in each group are decided for representative radio communication terminal units. The representative radio communication terminal units 1-1, 2-1 and 3-1 have the transmission/reception functions of beacon information. Mobile terminal units in the respective groups receive beacon information and manage communication time. When the groups are brought close to each other and the respective group representative mobile terminal units receive beacon information, a synchronous procedure for managing communication time is executed in accordance with the beacon information whose priority is higher.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication system, and more particularly to an improvement in a communication system between a plurality of mobile units grouped without requiring a central control station (base station).

[0002]

2. Description of the Related Art If a plurality of mobile units (vehicles) can wirelessly communicate with each other by a wireless communication system between the mobile units, the system is, for example, a traffic system or a railway vehicle system. It is very expected in the operation of the. Specifically, if the following vehicle on the same route can obtain the speed and abnormality information of the preceding vehicle by the system, it becomes very valuable information for the following vehicle. For example, Japanese Patent Laid-Open Publication No.
A wireless communication system using a centralized control station (base station) such as No. 2 has been proposed.

[0003]

However, in such a system, a great load is spent on maintenance of a base station and a backbone. Also, since the performance of the base station affects the communication performance of the system, the installation of the base station is the most important point in system construction. In addition, when direct communication between mobile terminals is the main purpose of use, there is a problem that it is not suitable. Therefore, means for easily constructing a wireless communication system without affecting communication performance in wireless system construction is desired.

[0004] An object of the present invention is to provide a radio communication system which enables radio communication between a plurality of mobiles without requiring the installation of such a base station.

[0005]

In order to achieve the above object, a plurality of wireless communication terminals belong to each of a plurality of groups according to the present invention. Control means, wherein at least one representative wireless communication terminal device of each group has a function of transmitting and receiving beacon information, and other wireless communication terminal devices have a function of receiving the beacon information, Includes time information of the clock means, transmission interval information of beacon information, period information in which the group to which the representative wireless communication terminal belongs can communicate, ID information of the group, and the like. The gist is that communication is performed based on beacon information.

In the wireless communication system of the present invention,
Upon receiving the beacon information, the representative wireless communication terminal device of each of the groups compares the ID information, and corrects the beacon time according to the time information received by its own clock means when the priority is high. , The time of each group may be synchronized.

Further, in each of the above-mentioned radio communication systems of the present invention, the radio communication terminal equipment is mounted on each mobile unit, and the mobile units of each group move in substantially the same direction within a communicable range. You may.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 3 are explanatory diagrams of one embodiment of a wireless communication system according to the present invention. FIG. 1A shows a wireless communication system according to the present invention in a case where there are a plurality of grouped mobile bodies and a plurality of groups, for example, in three groups Group1 to 3, three groups 1 are mounted on three mobile bodies. Wireless communication terminal devices 1-1 to 1-3, Group
In No. 2, the wireless communication terminal device 2-
Groups 1-2, 3 and 3 consist of wireless communication terminal devices 3-1 to 3-3 mounted on three mobile bodies and operate according to the communication procedure shown in FIG. In this case, the communicable conditions of the mobile-mounted wireless communication terminal devices constituting each group are as follows:
This means that the moving objects exist within a short distance range where they can communicate with each other, and move in almost the same direction (the destination of the movement is the same). FIG. 1B shows a schematic configuration of a wireless communication terminal device.
4 is a wireless communication device, 5 is a data processing device (CPU), 51
Is an internal clock section, the wireless communication device 4 is a transmission / reception antenna 41,
It comprises a wireless communication unit 42, a memory unit 43, a control unit 44, and an interface unit 45.

FIG. 2 shows an example of a communication procedure of mobile radio communication terminal devices (hereinafter, referred to as mobile terminal devices) in respective groups on a time axis. For example, during the communication period of group 1, the mobile terminal devices 1-1 to 1-3 belonging to group 1
Are allowed to communicate with each other, and the communication period of group 2 is the mobile terminal device 2-1, 2-2 belonging to group 2.
The communication period of the group 3 is a period during which the mobile terminal devices 3-1 to 3-3 belonging to the group 3 are respectively permitted to communicate.

[0010] Within the communication period permitted to each group,
The mobile terminal devices belonging to the group can communicate freely. As the access means, for example, a well-known contention method such as ALOHA or CSMA is adopted.

[0011] The above-mentioned communication period corresponds to at least one representative mobile terminal device (for example, 1-1, 2-1,
It is managed by a special function called a beacon given in 3-1). This function is shown in FIG. 3 in order to manage the communication time (reference time) of the mobile terminal devices in each group. All mobile terminal devices can receive this beacon information, and the communication time of the mobile terminal devices in the group is managed based on the beacon information.

In FIG. 1, the time is the time at which the beacon information is transmitted from the internal clock 51 of the representative mobile terminal device that transmits the beacon information. The interval indicates a time interval at which the representative mobile terminal device transmits beacon information. The term indicates a time (period) during which the group that transmitted the beacon information can communicate. Group (Gr
oup) ID is an ID (identification code) indicating a group to which the representative mobile terminal device that transmitted the beacon information belongs.
In addition, it is also possible to add individual information necessary for operation of the application destination system.

[0013] Mobile terminal devices other than the representative in each group adjust the time of the internal clock section of their own terminal based on the time information included in the beacon information if it is the beacon information of the own group. Thereby, time synchronization of mobile terminal devices belonging to the group can be performed, and further, the reception time of the next beacon information of the group can be predicted.

The representative mobile terminal devices of each group that can transmit the beacon information have a table of the contents shown in FIG. 3 in the memory unit 43. When the operation starts, the internal clock unit 51 and the data processing unit 5 operate. It has a function of transmitting beacon information at a time calculated from the beacon interval.

Next, a method of using the beacon information in the entire system will be described. As can be seen from FIG. 2, the beacon information is a communication time (period) of a specific group.
And so on. That is, by receiving the beacon information, it is understood that a certain period of time (indicated by the received beacon information) is a communication time (period) in which the group indicated by the beacon information can be used. This aims to reduce communication collisions by grouping a large number of mobile terminal devices and allocating communication time for each group.

The beacon information is used for obtaining synchronization between groups. Representative mobile terminal device of each group that has received beacon information (has a function to transmit beacon information)
Performs the following processing based on the beacon information.

The group IDs are compared, and if the priority is higher than the own group, the operation is executed. If the priority is low, do nothing. The clock unit 51 of the own terminal is adjusted to the received time information. The communication allocation time of the own group is calculated from the time information and the Group ID. The beacon time transmitted by the own station (representative mobile terminal device) is corrected based on the calculated value.

By performing this processing, the time of each group is synchronized, and the schedule can be assembled without overlapping the communication time allocation of each group. This is a very effective means for solving the problem that the communication time allocation of each group is duplicated by simple group division and prevents collision avoidance of communication.

The time synchronization of the group will be described in more detail. The description will be given using a system composed of three groups as shown in FIG. In the figure,
Group 1 shows a case where no other groups that can communicate are in the communication area, and groups 2 and 3 are in an area where they can communicate with each other. In this case, the mobile terminal devices of group 2 and group 3 are in a state where they can receive beacon information of each other. From this, the representative mobile terminal devices of each group are synchronized according to the above procedure from the received beacon information, and further, each mobile terminal of each group that receives beacon information newly transmitted based on the synchronized beacon information The devices will also be synchronized.
Then, for example, group 2 and group 3 are group 1
, The groups 1, 2, and 3 are synchronized by the same procedure. By moving each mobile terminal device (group) in this way, the entire system is synchronized.

Further, for example, a group in a left state such as group 1 is operated independently without synchronization, and in this case, the wireless communication of this group is performed by another group. It does not cause any problems because it is not affected (by other groups).

A specific operation example will be described with reference to FIGS. 4 and 5, the entire system is composed of three groups. Each group has one to three IDs
Is assigned. The number of mobile terminal devices in each group does not matter here. Representative mobile terminal devices 1-1, 2-1 and 3- of each group
Reference numeral 1 denotes a beacon information transmission plan criterion for establishing a beacon information transmission plan based on the time count of the internal clock section of the own station at the start of operation. The communication time allocated to each group is, for example, 1
0 msec. The time count of the internal clock unit is in units of 10 msec. Group 1 transmits beacon information at a time divisible by 3, for example. Group 2, for example, transmits beacon information at an extra time when divided by 3. The group 3 transmits the beacon information at a time that is, for example, two times after being divided by three.

As the priority of the group ID, the smaller the value, the higher the priority. Thus, the group synchronization function of the system is as follows. The representative mobile terminal device of each group makes a beacon information transmission plan based on the time count of its own internal clock section, and transmits the beacon information at a predetermined time. Since the mobile terminal devices of the group 1 are in the single communication area, the representative mobile terminal device 1-1 independently transmits beacon information without performing a synchronization operation. Since the mobile terminal devices of the groups 2 and 3 can receive each other's beacon information, a synchronization operation is performed. In this case, synchronization is established at the time of the beacon information of group 2 based on the priority of the ID. Thereafter, if the groups 2 and 3 move in the direction of the group 1, the beacon information of each other can be received. Here, the group 1 and the group 2 are synchronized. Synchronization work of group 1, group 2 and group 3
Synchronization is performed at the time of the beacon information of group 1 based on the priority of the group ID. In this way, as the mobile terminal device moves, the groups are synchronized, and the synchronization of the entire system is uniquely determined.

Finally, this system has been described on the premise that the terminal equipment is mounted on a mobile body. However, even if there is a group of fixed stations that do not move, the system can be operated without any problem.

[0024]

As is apparent from the above description, according to the present invention, communication between mobile units can be freely performed without using a centralized control station (base station). Communication efficiency can be significantly improved by grouping and group synchronization.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a mobile wireless communication terminal device grouped in an embodiment of a wireless communication system of the present invention and a schematic configuration of the device.

FIG. 2 is a diagram showing a communication order shown in time series between the terminal devices.

FIG. 3 is a diagram illustrating contents of beacon information used in the present invention.

FIG. 4 is a diagram for explaining a synchronization operation between groups in the wireless communication system of the present invention.

FIG. 5 is a diagram showing an acquisition time procedure of the synchronous work.

[Explanation of symbols]

 1-1, 2-1 and 3-1 Representative mobile terminal devices 1-2 Mobile terminal devices 1-3 Mobile terminal devices 2-2 Mobile terminal devices 3-2 Mobile terminal devices 3-3 Mobile terminal devices

Claims (3)

[Claims] A plurality of wireless communication terminal devices belong to each of the plurality of groups, and the wireless communication terminal devices include:
The communication device includes a clock unit, a transmission / reception unit, and a control unit. At least one representative wireless communication terminal device of each group has a function of transmitting and receiving beacon information, and another wireless communication terminal device has a function of receiving the beacon information. The beacon information includes time information of the clock means, transmission interval information of the beacon information, information on a period in which the group to which the representative wireless communication terminal device belongs can communicate, ID information of the group, and the like. A wireless communication network system, wherein the communication terminal device is configured to perform communication based on the beacon information. 2. The representative wireless communication terminal device of each of the groups compares the ID information when receiving the beacon information, and adjusts the beacon according to the time information received by its own clock means when the priority is high. By correcting the time,
2. The wireless communication network system according to claim 1, wherein time synchronization is performed for each group. 3. The wireless communication device according to claim 1, wherein the wireless communication terminal devices are respectively mounted on mobile units, and the mobile units of each group move in substantially the same direction within a communicable range. Communication network system.