JPH0767186B2 - Mobile communication system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mobile communication system, and more particularly to a mobile communication system suitable for communication with a vehicle such as an automobile.

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

(Problems to be Solved by the Invention) In the cellular system, different frequencies are used between a plurality of adjacent zones, that is, cells, in order to avoid radio wave interference. In order to effectively use the limited frequency band, it is preferable to subdivide the zone structure and repeatedly use the same frequency. However, the subdivision of the zone structure increases the frequency of frequency switching accompanying movement across the zones, and imposes a frequency switching control burden on both the base station and the mobile station. This tendency becomes more remarkable as the moving speed of the moving body increases. In order to solve this problem, it has been necessary in the conventional cellular system to widen each zone or increase the allocated frequency. However, as is well known, increasing the frequency allocation is very difficult.

The conventional cellular car telephone system is designed mainly for voice communication, and is not necessarily suitable for the service purpose of transmitting a large amount of data at high speed. For example, in land transportation such as automobiles, in order to efficiently manage the navigation that guides the route to an appropriate route according to the road congestion and weather conditions, and the efficient management of the operation of a large number of vehicles, the It is necessary to transmit a large amount of data at high speed. The conventional car telephone system is not necessarily suitable for various services including such high-speed data communication because the frequency of the transmission signal 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 capable of high-speed communication without occupying many frequencies.

(Means for Solving the Problems) A mobile communication system according to the present invention communicates with a plurality of base stations that respectively communicate with a mobile station via a wireless link and that accommodates a plurality of base stations. A plurality of base stations that are close to each other, including a communication network to be exchanged, are separated from each other by interposing a region in which the mobile station does not substantially respond to the radio waves of the radio link. Base stations are allowed to use a single frequency as a radio wave for countless links.

(Operation) According to the present invention, communication is performed with a base station while the mobile station is within a service area capable of responding to a radio wave from any of a plurality of base stations. Therefore, multiple base stations
The same frequency can be effectively used for the mobile station in at least one direction of communication. The mobile station communicates with the communication network through the base station while it is in the service area of any base station, and does not perform communication when it is in the no-radio wave area to the adjacent base station. As a result, a plurality of base stations can effectively use the same frequency, and realize high-speed communication and various services for mobile objects.

(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 traffic, particularly road traffic of vehicles including automobiles, as an individual road-vehicle communication system. In this embodiment, a plurality of roadside stations 10 are normally arranged along a general road or a highway at a predetermined interval, for example, several hundred meters to several kilometers. This interval may be set to an appropriate value according to the vehicle speed allowed on the road, for example. The roadside station 10 is a ground station that functions as a base station that wirelessly communicates with a subscribing vehicle 12 on the road.

The roadside station 10 has a transmitter / receiver 14, which transmits and receives radio waves 18 to and from a mobile station mounted in the subscribing vehicle 12, that is, a vehicle-mounted device 16 (FIG. 2), and its service area or zone 20.
It communicates with the vehicle 12 existing inside. One of the characteristics of this embodiment is that the size of the zone 20 is much smaller than the arrangement interval of the roadside stations 10 and the roadside stations 10 are intermittently arranged. The diameter may be, for example, on the order of tens of meters to 100 meters. Therefore, between two adjacent zones 20, there is a region 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 region", and the vehicle 12 is included in the zone 20. It is possible to communicate with the roadside station 10 only while it is present. This communication is performed at high speed.

As can be seen, in this method, the adjacent roadside stations 10
Also, the same frequency can be effectively used repeatedly. Therefore, it is basically sufficient for the radio link between the roadside station 10 and the mobile station 16 to use a single frequency throughout the system. In the case of a system that enables full-duplex communication, a pair of frequencies that are different from each other above and below are used. This eliminates the need for frequency zone switching as in the conventional cellular system. Due to these characteristics, this 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 a road-to-vehicle individual communication line network 22, and in the present embodiment, via the line network 22, a general telephone line network 24, a data exchange network 25 such as a general packet exchange network, and a system center 26. And access to other communication facilities such as user center 28. In this embodiment, the road-to-vehicle individual communication line network 22 has a station-level structure as illustrated in FIG. 2, and is provided between the general telephone line network 24, the data exchange network 25 and the centers 26, 28 and the mobile station 16. It is a communication network that performs switching, that is, switching. This will be described in detail later.

In such an intermittent minimum zone system, the mobile station 16 and
Communication with 10 can be speeded up, and various services including high-speed data communication will be provided. For example, for the purpose of navigation that guides a subscribing vehicle 12 such as an automobile to an appropriate route according to road congestion and weather conditions, and to efficiently manage the operation of a large number of vehicles 12, an individual road-vehicle communication network 22 is provided. Data communication can be performed between the centers 26 and 28 and the mobile station 16 via the center.

Referring to FIG. 2, the road-to-vehicle individual communication line network 22 in the present embodiment includes a plurality of roadside stations 10 arranged in a certain area.
Has a hierarchical structure including a regional station 30 in which a plurality of regional stations 30 are accommodated, a regional station 32 in which a plurality of regional stations 30 are accommodated over an area, and a general bureau 34 in which some of these regional stations 32 are accommodated. These stations 30, 32, and 34 including the on-road station 10 are referred to as ground stations. In the present embodiment, the line between the district station 30, the regional station 32, and the general bureau 34 forms a tree network consisting of trunk lines 36 such as trunk lines and diagonal lines, and the network between the general bureaus 34 is a network. Form a type network. It is needless to say that the present invention is not limited to this network form, and may have a local hierarchy structure according to the road form such as an ordinary road or an expressway, and other forms such as a linear network. Yes.

The trunk line 38 for the general public telephone line network 24 and the data exchange network 25 is accommodated in the general bureau 34, for example. The system center 26 is, for example, an information processing system that processes navigation of the joining vehicle 12. User Center 28
Is an information processing system for independently managing the operation of the belonging vehicles 12 belonging to a specific user. Both are accommodated in the general bureau 34 by the trunk line 40. Of course, these may be connected to the regional office 32 or the district office 30.

The general bureau 34, the regional bureau 32 and the district bureau 30 each have a unique station code. Of these, General Administration Bureau 34 and Regional Bureau
By expressing the 32 codes in the station hierarchy, regional stations
A registered ground station code 52 (FIG. 3) identifying 32 is formed. For a large number of users' vehicles 12 that have a large number of vehicles 12, a user code specific to the user may be used instead of the regional station code. The mobile station 16 mounted on the subscribing vehicle 12 is registered in the regional station 32 in the present embodiment, and a unique mobile station code 54 is given to the regional station 32. Therefore, nationwide, the in-vehicle device or mobile station 16
Are identified by ground station code 52 and mobile station code 54. The joining vehicle 12 may be registered in the general bureau 34 or the district bureau 30.

The vehicle-specific code that identifies the mobile station 16 is composed of a static code 50 and a dynamic code 60 in this embodiment, as shown in FIG. The static code 50 is a code that identifies the mobile station 16 registered in the regional station 32, and includes a ground station code 52 and a mobile station code 54, and a system code 56 for identifying this system. The system code 56 is a code that specifies this system in distinction from other systems, and may be omitted inside this system. Therefore, in addition to the function as the identification number of each mobile station 16 inside the system, the static code 50 is added to the mobile station 16 from the general telephone line network 24, the data exchange network 25 or the centers 26 and 28. It is closely related to the number system of.

The dynamic code 60 is a code corresponding to the moving state of the joining vehicle 12, and is effectively used for grasping and navigating the current situation of the joining vehicle 12. Therefore, the code is a vehicle-specific code related to the traveled area and the traveling status of the subscribing vehicle 12, and is the general telephone line network 24, the data exchange network 25, and the centers 26, 28.
Plays an important role in, for example, searching for a vehicle location for individual communication from the vehicle and providing route guidance information to the travel destination of the joining vehicle 12. Therefore, in the present embodiment, a destination code 62 indicating the operation destination of the subscribing vehicle 12 and a traveling area code 64 indicating the current traveling area are included. Driving area code 64 is
It is composed of station codes of general bureau 34, regional bureau 32 and district bureau 30. In addition to this, a link code for specifying the set communication link may be included.

In this embodiment, as shown in FIG. 2, the traveling vehicle table 80
Are available at Regional Bureau 32. The traveling vehicle table 80 stores, for each station area, data indicating the current traveling area of the joining vehicle 12 of the own station registered as belonging to the regional station 32. Data of the subscribing vehicle 12 traveling in the area is stored for each registration station. These data in the traveling vehicle table 80 are constantly updated. A similar vehicle table is shown in the figure
For example, district station 30
It may also be provided at the general bureau 34.

As conceptually shown in FIG. 1, the roadside station 10 is provided with a memory 42, which stores a passing vehicle table 82 (FIG. 2) and information to be transmitted to and received from the mobile station 16. Storage area. The passing vehicle table 82 is the minimum zone of the roadside station 10.
It holds the data on the joining vehicle 12 passing 20. These data include vehicle-specific codes 50 and 60, and are constantly updated as the joining vehicle 12 passes.

The mobile station 16 is mounted on a subscribing vehicle 12 such as an automobile in this embodiment, and transmits and receives data such as navigation information and operation management information, messages and image signals to and from the roadside station 10, and transmits those signals to the passengers. It is an in-vehicle device that can be visually and / or audibly displayed on the. Preferably, it is provided with a video display, a facsimile transmitting / receiving device, a voice synthesizing device, and the like that interface with the passengers by images and voice. Moreover, you may have the automatic operation control function with respect to the control mechanism of the joining vehicle 1. The mobile station 16 has a random number table function, and in response to polling from the roadside station 10, among the plurality of channels in the link 18 with the roadside station 10, an available free channel is selected by the roadside station 10. It

The communication between the mobile station 16 of the subscribing vehicle 12 and the base station 10 is carried out by polling with the frame 100 of the format illustrated in FIG. 4 in this embodiment. In this embodiment, the frame 100 has a cycle of 683 milliseconds (ms) and a transmission rate of 512 Kbits / second, and a plurality of channels are multiplexed in a large number of time slots included therein. In principle, required bidirectional communication is completed within this one frame period. Wireless link
A single frequency is used for 18. For full-duplex communication,
A pair of frequencies that are different from each other above and below is used. However, those frequencies may be fixed, and the same frequency is used regardless of which on-road station 10 zone 20 the joining vehicle 12 moves to.

An introduction unit 102 is located at the head of the frame 100, and includes a preamble, a synchronization signal, a polling identification signal, a code of the roadside station 10, and the like. Road station 10 using this
Polls the mobile station 16 in the zone 20 at a predetermined cycle, as shown in FIG. The mobile station 16 is in the reception mode in the idle state, and is in the transmission mode after the reception of the introduction unit 102 is completed.

The introduction unit 102 is followed by the vehicle recognition unit 104, which is a mobile station.
16 is a period in which the vehicle-specific codes 50 and 60 are transmitted in response to polling, and the roadside station 10 recognizes this. Advantageously, the two-block repetitive transmission greatly improves the recognition rate of the joining vehicle 12. The mobile station 16 selects an available free channel from the plurality of channels from the random number table in response to the polling. The static vehicle specific code 50 and the service function code are transmitted to the roadside station 10 using this channel (see FIG. 5).

In the present embodiment, a broadcast communication unit 106 is arranged following the vehicle recognition unit 104, and by using this, beacon type dynamic navigation information such as traffic information from the roadside station 10 and a registration response signal (ACK or NACK) are transmitted. It is transmitted to the mobile station 16 (FIG. 5). If the channel selected by the mobile station 16 does not collide with the vertical, this is registered in the on-road station 10 and the ACK signal is transmitted to the mobile station 16
Sent to.

After that, the vehicle communication unit 108 follows, and in this embodiment, full-duplex communication is performed between the roadside station 10 and the mobile station 16 as shown in FIG. The frequencies are different from each other above and below, and the channel selected by the roadside station 10 is used. However, even if the joining vehicle 12 moves to the zone 20 of the adjacent roadside station 10, the same frequency is used. 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 or the user center 28, and the passengers of the subscribing vehicle 12 receive the information. It is displayed as an image or sound. Further, communication with the general telephone line network 24, the data exchange network 25, or another mobile station 16 in the present system is similarly performed.

In the roadside station 10, the zone 20
The data of the joining vehicle 12 obtained from the mobile station 16 may be held in the passing vehicle table 82. The roadside station 10 transfers these data to the district station 30, regional station 32 or general station 34 through the line 36. These stations store the data thus transferred in, for example, the traveling vehicle table 80. Thus, for example, the traveling vehicle table 80 of the regional station 32 is constantly updated with new data.

Information destined for the mobile station 16 from the centers 26, 28, the general telephone network 24, and the data exchange network 25 is temporarily stored in any one of these stations, for example, the memory 42 of the roadside station 10. Road station 10
Then, the static vehicle specific code obtained from the mobile station 16 in the service area
50 is compared with the destination code of the transmission information to check whether there is information to be transmitted to the corresponding mobile station 16. When a match between the two is detected, the information stored in the memory 42 is transmitted to the mobile station 16 using the downlink channel of the vehicle communication unit 108. The information transmitted from the mobile station 16 through the uplink channel is temporarily stored in the memory 42. This upstream transmission information is later transferred to the centers 26, 28, the data exchange network 25, or the general telephone network 24 via the road-vehicle individual communication network 22.

When the vehicle communication unit 108 ends, the upper and lower response signals (the fifth
This is followed by a communication completion unit 110 which sends (Fig.). This is a signal confirming the completion of transmission, not confirmation of information content.

In this way, communication of one frame 100 is performed by the subscribing vehicle 12 on the roadside station 1
It is performed while driving in the service zone 20 of 0. The mobile station 16 cannot communicate with the road-to-vehicle individual communication network 22 while the subscribing vehicle 12 is traveling in the radio-free area between the two adjacent zones 20. The use of a single frequency may envision a conventional leaky coaxial cable broadcasting system. However, the present embodiment is fundamentally different from the leaky coaxial cable broadcasting system in that it is not a broadcasting system but an individual communication system, and that there is no radio wave area.

In this embodiment, as a general rule, there is a minimum zone 20 where there are subscribing vehicles 12.
One communication is completed while being included in. As long as the vehicle is traveling normally on an ordinary road or an expressway, the joining vehicle 12 travels in several minimum zones 20 across the above-mentioned non-radio wave area, which causes a considerable gathering. Road stations 10 are arranged along the road at intervals such that they can perform communication. In other words, such a spaced arrangement of the on-road station 10 can sufficiently achieve the required communication even for the mobile station 16 having a large amount of communication traffic.

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

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

(Effects of the Invention) The mobile communication system according to the present invention thus adopts the intermittent minimum zone system. As a result, the same frequency is effectively used repeatedly. In addition, high-speed communication is possible with a mobile body, and various services including high-speed data communication are provided. Further, it is not necessary to perform frequency zone switching as in the conventional cellular system, and the control is simplified. Therefore, high-speed communication is possible without occupying many frequencies.

[Brief description of drawings]

FIG. 1 is a conceptual block diagram showing an embodiment in which a mobile communication system according to the present invention is applied to road traffic of a vehicle as a road-to-vehicle individual communication system, and FIG. 2 is a road-to-vehicle space in the embodiment shown in FIG. FIG. 3 is a relay system diagram showing an example of a station level configuration of an individual communication line network, FIG. 3 is an explanatory diagram showing an example of a vehicle-specific code format in the same embodiment, and FIG. 4 is an example of a 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 roadside station in the embodiment. Explanation of main part code 10 …… Road station 12 …… Joined vehicle 14 …… Transceiver 20 …… Minimum zone 22 …… Road-to-vehicle individual communication network 42 …… Memory 80 …… Traveling vehicle table 82 …… Passing vehicle table

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Claims (1)

[Claims] 1. A plurality of base stations each communicating with a mobile station via a wireless link, and a plurality of exchanges forming a communication circuit network accommodating the plurality of base stations and exchanging communication with the plurality of base stations. A mobile communication system in which adjacent ones of the plurality of base stations are spaced apart from each other by interposing a region in which the mobile station does not substantially respond to the radio wave of the radio link. In the above, the mobile station is registered in any of the plurality of exchange stations, and locally related stations of the plurality of base stations form a group and are accommodated in one of the plurality of exchange stations, The switching center that registers the mobile station transmits information to the mobile station registered in the switching center to one switching center that accommodates a group of base stations in which the mobile station is located, and the one switching center. When the station receives the transmitted information, Transmitting information to a base station forming a group of base stations in which the mobile station is located, and when the base stations forming the group receive the transmitted information, the base station forming the group transmits the received information to the mobile station. A mobile communication system, characterized in that the radio waves are transmitted to a station using the same single frequency.