JPH01309427A - Mobile body communication system - Google Patents

Abstract

PURPOSE:To use a single frequency for a radio wave in a radio link by arranging base stations placed close to each other among plural base stations separately while an area is interposed inbetween where a mobile station does not substantially respond to a radio wave of the radio link. CONSTITUTION:An on-road station 10 has a transmitter-receiver 14, sends/ receives a radio wave 18 with a mobile station mounted on a subscriber car 12 and makes communication with the car 12 in existence within a zone 20. The size of the zone 20 is far smaller than the arrangement interval of on-road stations 10, which are arranged intermittently. The car 12 makes communication with the on-road station 10 while it is in existence in the zone 20. The communication is implemented at a high speed. Thus, the same frequency is used effectively repetitively as to the adjacent on-road stations 10.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a mobile communication system, and more specifically to a mobile communication system suitable for communication with a vehicle such as an automobile.

(Prior Art) A conventional mobile communication system to which the present invention is particularly relevant is, for example, a car telephone system. As is well known, in a conventional mobile telephone system, base stations serving a predetermined service zone are arranged two-dimensionally, and the zones of adjacent base stations partially overlap with each other.
Some use a cellular system that guarantees continuity of communication to mobile units.

(Problems to be Solved by the Invention) In the cellular system, different frequencies are used between a plurality of adjacent zones, that is, cells, to avoid radio wave interference. In order to effectively utilize a limited frequency band, it is preferable to subdivide the zone configuration and use the same frequency repeatedly. However, the fragmentation of the zone structure increases the frequency of frequency switching associated with movement across zones, placing a burden on both base stations and mobile stations to control frequency switching. This tendency becomes more pronounced as the moving speed of the moving object increases. To solve this problem, in conventional cellular systems, it was necessary to widen each zone or increase the allocated frequencies. However, as is well known, increasing frequency allocation is extremely difficult.

Conventional cellular car phone systems are designed primarily for voice communication, and are therefore not necessarily suitable for services that transmit large amounts of data at high speeds. For example, in land transportation such as automobiles, in order to perform navigation to guide people to appropriate routes depending on road congestion and weather conditions, and to efficiently manage the operation of large numbers of vehicles,
It is necessary to transmit large amounts of data at high speed between the on-board equipment and the two base stations on the ground. Conventional car phone systems are not necessarily suitable for a wide variety of services, including high-speed data communications, because the frequency of transmission signals is limited to the voice band.

In view of such demands for mobile communication, the present invention aims to provide a new mobile communication system that is capable of high-speed communication without occupying many frequencies.

(Means for Solving the Problems) A mobile communication system according to the present invention includes a plurality of base stations that each communicate with a mobile station via a wireless link, and a mobile communication system that accommodates a plurality of base stations and that communicates with these base stations. A plurality of adjacent base stations, including a communication line network to be exchanged, are spaced apart from each other by interposing an area in which the mobile station does not substantially respond to the radio waves of the wireless link. base stations are allowed to use a single frequency for their radio links.

(Function) According to the present invention, while a mobile station is within a service area that can respond to radio waves from any of a plurality of base stations, it communicates with that base station. Therefore, multiple base stations
The same frequency can be effectively used for at least one direction of communication for the mobile station. A mobile station communicates with a communication network through the base station while it is in the service area of any base station, and does not communicate when it is in a radio waveless area to a nearby base station. This allows multiple base stations to effectively use the same frequency, realizing high-speed communications and a variety of services for mobile units.

(Example) Next, an example of a mobile communication system according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment in which the mobile communication system according to the present invention is applied to land transportation, particularly road traffic for vehicles including automobiles, as a road-to-vehicle individual communication system. In this embodiment, a plurality of roads are usually arranged at predetermined intervals, for example, at intervals of several hundred meters to several kilometers, along a general road or expressway. This interval is
For example, it may be set to an appropriate value depending on the vehicle speed allowed on the road. The roadside station 10 is a ground station that functions as a base station that wirelessly communicates with participating vehicles 12 on the road.

The roadside station 10 has a transceiver 14, which is connected to the participating vehicle 1.
The mobile station 2 transmits and receives radio waves to and from a mobile station mounted on the vehicle 16 (FIG. 2), and communicates with vehicles 12 existing within its service area, ie, zone 20. One of the characteristics of this embodiment is that the size of the zone 20 is much smaller than the interval at which the roadside stations 10 are arranged, and the roadside stations 10 are arranged intermittently. Its diameter may be, for example, on the order of several tens of meters to 100 meters. Therefore, between two adjacent zones 20, there is an area where the mobile station 16 does not substantially respond to the radio waves transmitted by the roadside station 10, that is, a "no radio wave area", and the vehicle 12 is included in the zone 20. It is possible to communicate with the road station 10 only while the station is there. This communication takes place at high speed.

As will be seen from now on, in this method, the same frequency can be repeatedly and effectively used for the three adjacent roads 10. Therefore, basically, the road station 10 and the mobile station 1
6, it is sufficient to use a single frequency for the entire system. In the case of a system that allows full-duplex communication, a pair of frequencies that are different from each other are used.

This eliminates the need for frequency zone switching as in conventional cellular systems. Because of these characteristics, the wooden sword method is called the "intermittent minimum zone method" and the zone 20 is called the "minimum zone."

The roadside station 10 constitutes a part of the road-to-vehicle individual communication line network 22, and in this embodiment, data exchange 4QiiP1 such as a general telephone line network 24 and a general packet switching network is carried out via the line network 22.
25, a system center 28, and other communication facilities such as a user center 28. In this embodiment, the road-to-vehicle individual communication line network 22 has a station hierarchy configuration as illustrated in FIG. A communications network that performs switching or exchange.

This will be explained in detail later.

With such an intermittent minimal learn method, it is possible to increase the speed of communication between the mobile station 16 and the road station 1O, and a variety of services including high-speed data communication can be provided. For example, the road-to-vehicle individual communication network 22 is used for navigation purposes that guide member vehicles 12 such as cars to appropriate routes depending on road congestion and weather conditions, and for the purpose of efficiently managing the operation of a large number of vehicles 12. Data communication can take place between the centers 26 and 28 and the mobile station 18 via the mobile station 18.

Referring to FIG. 2, the road-to-vehicle individual communication line network 22 in this embodiment includes a district station 30 that accommodates a plurality of roadside stations 10 located in a certain area, and a district station 30 that accommodates a plurality of roadside stations 10 located in a certain area. It has a hierarchical structure consisting of earth stations 32 and a general office 34 that houses several of these earth stations 32. These stations 30.
32.34 is called ``three laps around the earth''.

In this embodiment, the lines between the district stations 30, the earth stations 32, and the general station 34 form a tree-like line network consisting of trunk lines and trunk lines 36 such as diagonal lines. It constitutes a type line network. It goes without saying that the present invention is not limited to this network configuration, and may take other configurations such as a local hierarchy structure depending on the road configuration such as a general road or an expressway, or a linear network. stomach.

A trunk line 38 for the general public telephone network 24 and the data exchange network 25 is housed in a central office 34, for example.

The system center 28 is, for example, an information processing system that processes navigation for the participating vehicle 12. Further, the user center 28 is an information processing system that independently manages the operation of the subscribed vehicles 12 belonging to a specific user. Both are accommodated in the central office 34 via a trunk line 40. Of course, these are earth station 32 and district station 30.
may be connected to.

The central station 34, the earth station 32, and the district stations 30 each have a unique station code. The registered ground station code 52 (third
) is formed. For a subscriber vehicle 12 of a large user who owns a large number of subscriber vehicles 12, a user code unique to that user may be used instead of the local station code.

In this embodiment, the mobile station 16 mounted on the participating vehicle 12 is registered with the earth station 32, and is assigned a unique mobile station code 54 at the earth station 32. Therefore, nationwide, the on-vehicle device or mobile station 16 is identified by the ground station code 52 and the mobile station code 54. Note that the participating vehicle 12 may be registered at the general office 34 or the district office 30.

The vehicle-specific code for identifying the mobile station 16 is composed of a static code 50 and a dynamic code 60 in this embodiment, as shown in FIG. Static need 50 is a code that identifies mobile station 16 registered with earth station 32, and includes earth station code 52, mobile station code 54, and system code 58 for identifying this system. The system code 56 is a code that specifies this system to distinguish it from other systems, and may be omitted inside this system. Therefore, in addition to serving as an identification number for each mobile station 16 within this system, the static code 50 also functions as an identification number for each mobile station 16 within the system.
．． This is closely related to the numbering system used when a call arrives from 28 to the mobile station 16.

The dynamic code 60 is a code corresponding to the movement state of the participating vehicle 12, and is effectively used to grasp the current situation of the participating vehicle 12 and navigate. Therefore, it is a vehicle-specific code related to the driving area and movement status of the subscriber vehicle 12, and is a code unique to the general telephone line network 24, data exchange network 25,
It plays an important role in searching the vehicle location for individual communication from the centers 26 and 28, and providing route guidance information to the travel destination of the participating vehicle 12. Therefore, in this embodiment, a destination code 62 indicating the destination of operation of the participating vehicle 12 and a driving area code 64 indicating the current driving area are included. The driving district code 84 is composed of the station codes of the general station 34, regional station 32, and district station 30. In addition to this, a link code that specifies the set communication link may also be included.゛In this embodiment, as shown in FIG.
0 is prepared in the regional station 32. Running vehicle table 8
0 stores data indicating the current driving area of the local station's member vehicles 12 registered as belonging to the local station 32, by station area, and also stores data indicating the current driving area of the local station's participating vehicles 12 registered as belonging to the local station 32. Data on participating vehicles 12 is stored for each registration station. These data in the running vehicle table 80 are constantly updated. A similar vehicle table is illustrated by a dotted line 84 in the case of the district office 30 in the same figure.
For example, it may be provided at the district office 30 and the general office 34 as well.

As conceptually shown in FIG.
2, which includes a passing vehicle table 82 (FIG. 2) and a storage area in which information to be sent to and received from the mobile station 16 is stored. The passing vehicle table 82 shows the road station 1
Data regarding the joining vehicle 12 passing through the zero minimum zone 20 is held. These data are vehicle specific code 5
0 and 60, and is constantly updated as the joining vehicle 12 passes.

In this embodiment, the mobile station 16 is a member vehicle 12 such as a car.
This is an in-vehicle device that transmits and receives data such as navigation information and operation management information, messages, and image signals to and from the roadside station 10, and displays these signals visually and/or audibly to passengers. Preferably, the vehicle is equipped with a video display, a facsimile transmitting/receiving device, a voice synthesizing device, etc., which provide an image and audio interface to the passenger. Further, it may have an automatic operation control function for the control mechanism of the participating vehicle 12. The mobile station 16 is equipped with a random number table function, and in response to polling from the road station 10, the mobile station 16 selects an available free channel from among a plurality of channels in one day of the link with the road station IO. be done.

In this embodiment, communication between the mobile station 16 of the participating vehicle 12 and the base station IO is carried out by polling using a frame 100 having a format as illustrated in FIG. In this example, frame 100 has a period of 883 milliseconds (ms).
, the transmission rate is 512 bits/second, and multiple channels are multiplexed into a number of time slots.

In principle, the required bidirectional communication is completed within this 1 frame period. A single frequency is used for wireless link 18. In the case of full-duplex communication, a pair of different frequencies are used for upper and lower frequencies. However, these frequencies may be fixed, and the same frequencies are used even if the joining vehicle 12 moves to the zone 20 of the third round trip 10.

An introduction section 102 is located at the beginning of the frame 100, and includes a preamble, a synchronization signal, a polling identification signal, a code for the road station 10, and the like.

Using this, the roadside station 10 polls the mobile station 18 within the zone 20 at a predetermined period, as shown in FIG.

The mobile station 16 is in the receiving mode in the idle state &, and becomes the transmitting mode when it finishes receiving the introduction part 102.

The introduction section 102 is followed by a vehicle recognition section 104, which includes:
Mobile station 16 responds to polling with vehicle specific code 50.
and 60 are transmitted, and the roadside station 10 recognizes this. Advantageously, by performing two-block repeated transmissions, the recognition rate of participating vehicles 12 is significantly improved. The mobile station 16 selects an available free channel from among the plurality of channels from the random number table in response to the polling. This channel is used to transmit static vehicle-specific codes 50 and service function codes to the roadside station 10 (see FIG. 5).

In this embodiment, the vehicle recognition unit 104 is followed by the vehicle recognition unit 104.
0B is arranged, and using this beacon-type dynamic navigation information such as traffic information and a registration response signal (ACK or NACK) are transmitted from the roadside station 1o to the mobile station 16 (FIG. 5). If the channel selected by the mobile station 16 does not conflict with any other channel, it is registered with the road station 10 and an ACK signal is transmitted to the mobile station 16.

This is followed by the vehicle communication section 108, and in this embodiment, as shown in FIG.
Full-duplex communication is performed between the two. The frequencies are different from each other and the channel selected by the road station 10 is used. However, the adjoining road' 3 laps 10 sone 20
The same frequency is used even if the subscribing vehicle 12 moves.

Of course, half-duplex or unidirectional communication may be used. ``In the vehicle communication unit 108, data such as navigation information and operation management information, messages, and image signals are transmitted and received between the mobile station 16 and the system center 26 and the user center 28, and the information is transmitted to the passenger of the subscriber vehicle 12. is displayed in the form of images and sounds. Furthermore, communications to the general telephone line network 24, data exchange network 25, or other mobile stations 16 in the tree system are performed in the same manner.

During the third round of the road 10, the data of participating vehicles 12 obtained from the mobile stations 16 within the zone 20 during the polling period may thus be maintained in the passing vehicle table 82.

The roadside station 10 transfers these data to a district station 30, a regional station 32, or a general station 34 through a line 36. These stations store the thus transferred data in, for example, a traveling vehicle table 80. In this way, for example, the traveling vehicle table 80 of the regional station 32 is constantly updated with new data.

Information addressed to the mobile station 16 from the center 26, 28, the general telephone line network 24, and the data exchange network 25 is temporarily stored in the memory 42 of one of these stations, for example, the roadside station 10. The roadside station 10 compares the static vehicle-specific code 50 obtained from the mobile station 16 within its jurisdiction with the destination code of the transmission information, and determines whether there is information to be transmitted to the corresponding mobile station 16. investigate. When a match is detected, the information stored in the memory 42 is transmitted to the mobile station 18 using the downlink channel of the vehicle communication section 108. Information transmitted from the mobile station 16 via the uplink channel is temporarily stored in the memory 42. This information is later sent to the center 26, 28 via the road-to-vehicle individual communication network 22.
The data is transferred to the data exchange network 25 or the general telephone line network 24.

When the vehicle communication unit 108 is finished, the upper and lower response signals (fifth
This is followed by a communication completion unit 110 that transmits the following information. This is a signal confirming the completion of the transmission, not confirmation of the information content.

In this way, the communication of the l frame 100 takes place while the participating vehicle 12 is traveling within the service lane 20 of the roadside station 10. While the subscribing vehicle 12 is traveling in a radio waveless area between two adjacent zones 20, the mobile station 16 cannot communicate with the road-to-vehicle individual communication network 22. Using a single frequency may evoke traditional leaky coaxial cable broadcast systems. However, this embodiment is not a broadcasting system but an individual communication system, and is fundamentally different from a leaky coaxial cable broadcasting system in that there is no radio wave area.

In principle, this embodiment is configured such that one communication is completed while the joining vehicle 12 is included in a certain minimal zone 20. Regardless of whether it is a general road or an expressway, as long as the vehicle is driving normally on that road, the vehicle 1 that has joined several minimal zones 20 across the above-mentioned no radio wave area.
Roadside stations 10 are arranged along the road at such intervals that a considerable amount of communication can be carried out by the traveling of the roadside stations 10. In other words, by arranging the roadside stations 10 at such a distance, the mobile station 1 with a large amount of communication traffic can
6, it is possible to sufficiently achieve the required communication.

An embodiment in which the present invention is applied to a road-to-vehicle individual communication system has been described. However, the present invention is not limited thereto, and can be effectively applied to individual communication with any moving object other than a vehicle, such as an individual, ie, a pedestrian in a broad sense.

Note that the embodiments described here are for explaining the present invention, and the present invention is not necessarily limited thereto, and modifications and variations that can be made by those skilled in the art without departing from the spirit of the present invention. Modifications are within the scope of this invention.

(Effects of the Invention) The mobile communication system according to the present invention employs the intermittent minimal zone method as described above. This allows the same frequency to be used repeatedly. In addition, high-speed communication is possible for mobile objects, and a variety of services including high-speed data communication are provided. Furthermore, there is no need to perform frequency zone switching as in conventional cellular systems, simplifying control. Therefore, high-speed communication is possible without occupying many frequencies.

[Brief explanation of the drawing]

FIG. 1 is a conceptual block diagram showing an embodiment in which the mobile communication system according to the present invention is applied to road traffic for vehicles as a road-to-vehicle individual communication system, and FIG. 2 is a road-to-vehicle individual communication system in the embodiment shown in FIG. Figure 3 is an explanatory diagram showing an example of the format of the vehicle-specific code in the same embodiment, and Figure 4 is an explanatory diagram showing an example of the frame format in the same embodiment. FIG. 5 is a sequence diagram showing an example of a communication sequence between a mobile station and a road station in the same embodiment. Explanation of symbols of main parts 10, Road station 12, Joining vehicle 14, Transmitter/receiver 20, Minimum zone 22, Road-to-vehicle individual communication network 42, Memory 80, Traveling Vehicle Table 8291 Passing Vehicle Table Patent Applicant: Oki Electric Industry Co., Ltd. Agent Address: Takao Inuyama, Rimata, Rimata Haritai Threshold, Published by: S, Asahi Naka 1 Town Code - Matsu) Example Plane 3 Diagram q +02 104 106 108
110 Frame Format Side U Figure 4 and

Claims (1)

[Scope of Claims] A plurality of base stations each communicating with a mobile station via a wireless link, and a communication line network accommodating the plurality of base stations and exchanging communications for the plurality of base stations, Adjacent ones of the plurality of base stations are spaced apart from each other with an area interposed therebetween in which the mobile station does not substantially respond to radio waves of the wireless link, whereby the plurality of base stations A mobile communication system characterized in that a single frequency is allowed to be used as the radio waves.