JPH11262054A - Radio communication system and subscriber use radio equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide sure and efficient communication to subscribers smoothly, even in the case of a mobile communication system where base stations cannot be arranged sufficiently densely and only intermittent communication is available between subscribers and the system in a short connection time. SOLUTION: This system is provided with a center 1, base stations 21-1-21-n, 22-1-22-n,..., 2k-1-2k-n that make transmission and reception with subscribers M by a radio signal, control stations 11-1m, that are placed between the base stations and the center and conduct transmission/reception of an information signal to/from plural base stations, and a center control station network 2 which interconnect the center and the control stations. In the case that a control station sends information to a specific subscriber M, the subscriber M informs the control station of reception ready. Then the control station receiving the notice transfers the information to the subscriber M. The subscriber side controls data transfer from the control station, and even in the case of the system where only intermittent communication is available, efficient communication is available without the need for accurate understanding of the position and communication state of each subscriber by the control stations or the center.

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 a radio for a subscriber, and more particularly to a radio communication system for transmitting a large amount of information to a subscriber moving by car or the like, and a radio for the subscriber used therefor. About the machine.

[0002]

2. Description of the Related Art With the spread of mobile communication, demands for outdoor communication are increasing. As one of them, communication while traveling by car is also popular, but in order to access applications such as images and executable files through the Internet etc., current mobile communication systems such as mobile phones require transmission capacity. Is missing. Therefore, next-generation mobile phone systems are being studied.

However, even in the system under consideration,
The target is about Mbps, and it cannot be said that the capacity is sufficient for future large-capacity multimedia communications, and the distribution of users is assumed to be uniform. In an environment where the density is high and there is a uniform movement, the load is concentrated on a specific base station, and a situation where only some of the subscribers can receive the service is likely to occur. Therefore, it has been studied to install a dedicated wireless communication system, especially on a motorway.

[0004] As a dedicated communication system on a motorway,
There is an information providing system using a leaky coaxial. This means that traffic information and the like can be received only at the place where the leaky coaxial is installed. However, transmission of high frequency and high power is difficult, so it is not suitable for large capacity transmission, and from the car side,
There was no setting for the uplink to make the request.

[0005] A dedicated radio communication system for data communication requires a sufficient transmission capacity to transmit a service requested by a subscriber in a multimedia format in addition to information from a center. In order to realize this, a radio system using a high frequency of a quasi-millimeter wave or a millimeter wave has been studied.

[0006] However, communication using quasi-millimeter waves or millimeter waves has a narrow communicable range due to the characteristics of the apparatus and the susceptibility to rain attenuation. Therefore, a large number of base stations are required. However, since it is difficult to manage and control them individually, and the price of the apparatus is high, base stations can be sparsely arranged. This results in intermittent communication between the subscriber and the system. Also, the car used by the subscriber is
Since the vehicle is moving every moment, the time required for communication between the vehicle and the system is short. Therefore, especially when used on an expressway, a certain series of communication is performed without repeating the connection between one communication connection and several times or several tens of times. Will go. In a certain subsystem in which the series of communication is performed, a plurality of vehicles (subscribers) are traveling at timings and speeds that are not related to each other, and these non-synchronous (asynchronous) subscriptions are performed. Communication will be provided to the user.

However, in the conventional mobile communication, it is not assumed that an environment where such asynchronous subscribers exist and communication can be performed only repeatedly is not assumed. A problem arises that the system does not operate well in a system where communication is intermittent.

[0008] For example, (1) if there is no response from the subscriber suddenly during data transfer from the base station to the subscriber, the base station retransmits the data. Doing so is wasteful communication. (2) When a subscriber makes a request for information, it is not always possible for the subscriber to receive information within the communicable range of the base station from which the request was made.

[0009]

As described above, in the conventional mobile communication, it is assumed that subscribers exist asynchronously using quasi-millimeter waves or millimeter waves, and that each of them can only communicate repeatedly. Therefore, the conventional data communication system used on the system does not operate well in a system where communication is intermittent.

In order to solve such a problem, the present invention is to efficiently provide a subscriber even in a system in which the subscriber exists asynchronously, and particularly in a system in which communication can be performed only intermittently. It is an object of the present invention to provide a wireless communication system and a subscriber wireless device capable of performing smooth and reliable communication.

[0011]

Means for Solving the Problems The first invention is claim 1.
As described in, a center that controls the entire wireless communication system, a base station that transmits and receives radio signals to and from a moving subscriber, and a plurality of base stations that are accommodated by broadband communication means such as an optical fiber to transmit and receive information signals Control station, and a wireless communication system having a center-control station network connecting the center and the control station, when the control station transmits information to a specific subscriber via the base station, Is characterized in that the subscriber notifies the control station using a signal indicating that reception is possible, and the control station which has received the reception permission notification transfers the information to the subscriber.

[0012] In the first invention, a data transfer from the control station can be controlled from the subscriber side by notifying the control station that the communication device on the subscriber side is in a receivable state. It is. This allows efficient communication even in a system that can only communicate intermittently.

According to a second aspect of the present invention, as set forth in the second aspect, the wireless communication system according to the first aspect has a function of detecting that a subscriber has entered a communicable range of the base station, The timing at which the subscriber transmits the signal indicating that reception is possible is performed based on the timing at which the subscriber detects that the subscriber has entered the communicable range of the base station.

According to a second aspect of the present invention, there is provided a system in which there is a dead zone between base stations and mobile subscribers can only intermittently communicate with a plurality of base stations.
When the subscriber detects that the subscriber has entered the communicable range of the base station, or at a time measured based on the detection timing (when there is remaining time available for communication with the base station), the subscriber sends a reception enable signal. Transfer to control station. Accordingly,
The control station can transmit information to a particular subscriber when the subscriber is within the coverage area.

According to a third aspect of the present invention, a center for controlling the entire radio communication system, a base station for transmitting and receiving radio signals to and from a moving subscriber,
In a wireless communication system including a plurality of base stations accommodated by broadband communication means such as an optical fiber and transmitting and receiving information signals, and a network between a center and a control station for connecting the center and the control station, The station converts the information requested by the information request signal from the subscriber into a radio signal, and receives the ID and the traveling speed of the subscriber that are intermittently transmitted from the subscriber using the uplink channel, The subscriber has a function of determining one or a plurality of base stations predicted to pass in the vicinity within a predetermined time, and transferring the wireless signal through the determined base station. Things.

In the third aspect of the present invention, the ID and the moving speed of the subscriber are transmitted from the communication device of the moving subscriber, and the control station receives the ID and the moving speed from among the plurality of base stations. Is determined, the system can cooperate between the base station and the control station so that communication with the subscriber can be performed reliably, smoothly, and continuously.

According to a fourth aspect of the present invention, as set forth in claim 4, a center for controlling the entire radio communication system, a base station for transmitting and receiving radio signals to and from a moving subscriber,
A plurality of base stations are accommodated in a broadband communication means such as an optical fiber, and a subscriber in a wireless communication system having a control station for transmitting and receiving information signals and a network between a center and a control station for connecting the center and the control station. In the subscriber radio used, the information request signal and the ID of the subscriber are transmitted to the base station, and after receiving a signal indicating the completion of transfer preparation from the base station, immediately or beforehand, or After a lapse of the given time, a signal indicating that reception is possible and the ID of the subscriber are performed using the uplink channel of the wireless communication system.
Is transmitted intermittently, and a function of receiving a signal having requested information using a downlink channel of the wireless communication system is provided.

According to the fourth aspect, in response to an information request from a subscriber, the communication device on the subscriber side can efficiently and reliably receive information corresponding to the request from the control station.

According to a fifth aspect of the present invention, as set forth in claim 5, a center for controlling the entire radio communication system, a base station for transmitting and receiving radio signals to and from a moving subscriber,
In a wireless communication system including a plurality of base stations accommodated by broadband communication means such as an optical fiber and transmitting and receiving information signals, and a network between a center and a control station for connecting the center and the control station, The station packetizes an information signal broadcast by the control station to a plurality of subscribers within a service range covered by a series of base stations accommodated by a certain broadband communication means. It has a function of transmitting a plurality of times, or, when the information signal becomes a plurality of packets, further has a function of transmitting the packets in a random order and transmitting each packet a plurality of times. Is what you do.

According to the fifth aspect, by transmitting the same information packet a plurality of times from the control station side, the communication apparatus on the subscriber side can reliably receive the information from the control station side. Further, when the information is composed of a plurality of packets, the plurality of packets are transmitted in a random order and each packet is transmitted a plurality of times, so that a dead zone exists between the base station and the base station so that the communication can be performed only intermittently. In a system, a communication device for a subscriber such as a car moving at high speed can receive information efficiently and reliably by reducing the probability that the same packet will be received each time it enters the communicable range of each base station. I can do it.

According to a sixth aspect of the present invention, a center for controlling the entire radio communication system, a base station for transmitting and receiving radio signals to and from a moving subscriber,
A plurality of base stations are accommodated in a broadband communication means such as an optical fiber, and a subscriber in a wireless communication system having a control station for transmitting and receiving information signals and a network between a center and a control station for connecting the center and the control station. When a packet transmitted from the base station and broadcast to the subscriber is received, a function for checking whether the packet has already been received, and A function of storing the packet when the packet is received for the first time, a function of checking whether or not the original information forming a part of the packet can be reproduced by storing the packet; If it is possible, the function to reproduce the original information and the received packet is duplicated with the already stored packet, or at other appropriate times, Examine packets stored in,
It has a function of finding a non-arriving packet necessary for reproducing the original information and transmitting a request signal requesting retransmission of the necessary non-arriving packet to the base station.

In the sixth invention, the communication device on the subscriber side reliably receives and stores information from the control station side,
The original information can be reproduced.

According to a seventh aspect of the present invention, a center for controlling the entire radio communication system, a base station for transmitting and receiving radio signals to and from a moving subscriber,
In a wireless communication system including a plurality of base stations accommodated by broadband communication means such as an optical fiber and transmitting and receiving information signals, and a network between a center and a control station for connecting the center and the control station, A local streamer is provided in the station, and the local streamer has a function of accumulating a part of information provided in an area where a base station accommodated by the control station is present and updating the information as necessary. Receiving the information request signal from the subscriber and the ID of the subscriber, and, if necessary, notifying the information request signal and the ID of the subscriber to another control station existing in the moving direction of the subscriber. The control station or the notified control station interprets the information request signal, and determines whether or not the information requested by the information request signal is in the local streamer connected to the control station. And determining whether the content exists in the center database.If the content does not exist in the local streamer and exists in the center database, the requested information is transmitted to the center using the network between the center and the control station. It has a function of downloading from the Internet.

According to the seventh invention, information requested frequently is stored in a local streamer provided in the control station, so that the control station can respond to the request without sending the request from the subscriber to the center. Can be. If the requested information is not in the local streamer, it can be downloaded from the center database to respond to the request. The system can cooperate between the base station and the control station, between the control station and the control station, and between the control station and the center so that continuous communication can be performed efficiently and smoothly.

[0025]

Embodiments of the present invention will be described with reference to the drawings. 1 to 8 show a wireless communication system according to the present invention. FIG. 1 is a diagram showing the overall configuration of the wireless communication system, FIG. 2 is a diagram showing an example of the center configuration in FIG. 1, and FIG. FIG. 4 is a diagram showing an example of a subsystem in FIG. 1, FIG. 5 is a diagram showing an example of a configuration of a base station in FIG. 1, and FIG. 6 is a subscriber communication device in FIG. FIG. 7 is a diagram showing an example of a communication flow in the first embodiment, and FIG. 8 is a diagram showing an example of the structure of an information packet. This wireless communication system makes it possible to provide a large-capacity data communication environment to a moving body such as a vehicle on an exclusive road for automobiles or the like.

In FIG. 1, a radio communication system includes a center 1, an inter-center / control station network 2, and m control stations 1
.., 1m and k provided for each control station
, 2k, and n base stations 21-1, 21--21 provided for each subsystem.
,..., 21-n. The center 1 controls the entire wireless communication system. The network 2 between centers and control stations connects the center 1 to m control stations 11 to 1m. Control stations 11 to 1m
Manages communication for each region, and is connected to the center 1 via the network 2 between the center and the control station. Each of the control stations 11, 12,..., 1m has k subsystems 21, 22,..., 2k in which a plurality of base stations are accommodated by k broadband communication means (such as optical fibers).
And transmits and receives information signals to and from a plurality of base stations or to the center 1. For example, the base stations 21-1, 21-2, ..., 21-n are:
A single subsystem 21 is configured by using a broadband communication means 31 such as an optical fiber. .., 2k wide-band communication means 3
, 3k are one control station, for example, control station 1
Connected to 1. That is, the m control stations 11, 12,.
.., 1 m manage one subsystem or a plurality of subsystems. Also, each base station
A wireless transmission / reception device for transmitting / receiving a wireless signal to / from a communication device (subscriber wireless device) on the subscriber side actually mounted on a mobile body M such as a car is provided.

FIG. 2 shows the structure of the center 1. The center 1 mainly includes the control unit 41 and the control stations 11, 12,.
.., 1 m, a center database including a database 43 for storing information and a database 44 for subscriber management, and an ITS (Intelligent Tra) for exchanging information with another communication system.
nsportation System) Integrated system interface (I
/ F) 45 and a gateway 46 for connecting to another network such as the Internet.

FIG. 3 shows the configuration of the control station 11. The control station 11 manages subsystems, communicates with the base station 21,
A control unit 51 for controlling communication with the center 1 and transfer / accumulation of information between them;
It has a transmission / reception unit 53 for a network between control stations, a local streamer 54 for storing information to be transferred, and the like.

A plurality of base stations (for example, 21-1, 21-2,..., 21-n) of each subsystem in FIG.
Are installed at intervals of 100 m, but the communicable range covered by the base station is a range of about 30 m in diameter,
There is an area (dead zone) between the base station and the base station where communication with the car M is not possible.

FIG. 4A shows a part of the subsystem 21. As the vehicle M on the road travels, each of the base stations 21-1
-21-n move from one coverage to another. The base station is installed, for example, at the upper end of a pole provided in a median strip, and an antenna is directed to look down on a road surface. On the other hand, on the vehicle side, the antenna is installed on the upper surface of the vehicle M, preferably on the left side of the vehicle M (corresponding to the traffic rule that the vehicle travels on the left side of the road). As a result, as shown in FIG. 4 (b), the vehicle M in the communicable range even on the multi-lane road can always communicate with the base station (for example, 21-2, 2k-2) in a line of sight. Has become. The radio section of this communication system uses a quasi-millimeter wave or millimeter wave band having a high frequency in order to perform large-capacity communication with the vehicle M. Therefore, as described above, the fact that the car M as the communication partner is always in sight contributes to stable communication. Also, as shown in FIG. 4 (b), the directivity of the antenna on the side of the car M should be only a component above the horizontal (that is, the directivity in which the directivity in the horizontal direction is deleted). Thereby, the interference between the vehicles M including the vehicle traveling in the oncoming lane can be reduced.

FIG. 5 shows the configuration of the base station 21-2.
In the subsystem, a set of downstream and upstream fiber cables 7
The control station and the base station are connected in series by 0-1 and 70-2. Here, the direction of communication sent from the base station to the subscriber side is called down, and the opposite direction is called up. At each base station,
The signal is separated by the coupler 62 from the downstream fiber 70-1 for transmitting the signal from the control station, and is reproduced by the optical receiver 63 into an electric signal. This signal is obtained by subjecting a plurality of channels to subcarrier modulation multiplexing. The signal is multiplied by a signal from a built-in oscillator OSC1 in a mixer 64, converted into a desired frequency band at a time, passed through a circulator 65, and passed through an antenna 6
It is emitted as a downstream radio signal via 6. One of the channels is used for controlling the base station 21, and only this channel is used by the base station 21 for the filter BPF.
And demodulated by the control monitoring unit 61. Thereby, for example, the frequencies of the oscillators OSC1 and OSC2 are adjusted. Also, the radio wave of the up signal from the car side,
The signal is input through an antenna 66 and a circulator 65, is multiplied by a signal from a built-in oscillator OSC2 in a mixer 67, and is downconverted to a predetermined frequency band. This down-converted signal is sent to the control monitoring unit 6
1 is added to the generated channel signal and supplied to the optical transmitter 68. In the optical transmitter 68, the electric signal is converted into an optical signal, and this optical signal is transmitted to the control station via the coupler 69 via the upstream fiber 70-2. Normally, since the amount of the upstream signal is small, the oscillation frequency of the oscillator OSC2 is set to be the same in each base station in the subsystem. At this time, in the upstream fiber 70-2, the fiber 70-
Uplink signals from the respective base stations connected to 2 are multiplexed in the same subcarrier frequency band, and the upstream control station can collectively receive them.

When the amount of data transmitted as an uplink signal is large, each base station adjusts the oscillation frequency of the oscillator OSC2 so that the frequency band in which the uplink signal is down-converted differs depending on the base station. can do. Therefore, at this time, even in the upstream fiber 70-2, the frequency of each upstream signal does not overlap, and the control station separates the upstream signal from each base station by frequency-demultiplexing the signal detected from the optical signal. Detection and demodulation can be performed separately.

As described above, the same downlink signal is sent from the control station to a plurality of base stations (21-1 to 21-n shown in FIG. 4A) in one subsystem. It is transmitted via the broadband communication means 31. Further, in order to transmit signals at a plurality of frequencies from each base station to the car (subscriber) side as well as signals for one channel,
Signals of several channels are modulated and multiplexed on subcarriers. As the multiplex transmission scheme, other schemes such as time multiplexing can be considered, and the configuration of the base station differs slightly depending on the scheme. In any case, the control station distributes one type of downlink signal to each base station. Each base station relays the upstream signal to the control station while multiplexing the upstream signal received from the vehicle (subscriber) side to the upstream signal in the upstream fiber 70-2. is there.

Next, the communication procedure will be described. First, means for detecting that a subscriber has entered the communicable range of the base station will be described. In the downlink, information from the system side (center, control station, and base station) is constantly broadcast. Information is collected at the center 1 and control stations 11 to 1m.
It is manufactured and the final contents are configured by the control station. The center 1 provides various information such as a wide range of road and traffic conditions, weather forecasts, construction schedules, and sightseeing information.
At m, local information is added. The frequency f1 is assigned to a channel (hereinafter, a downlink channel) for transmitting this downlink signal from a base station (for example, 21-1 to 21-n). When the subscriber uses the wireless communication system on a motorway, the subscriber always receives the downlink channel of the frequency f1 and receives the channel signal to thereby transmit the base station (for example, 21-1 to 21-). and n) detecting that it has entered a range where communication with the device can be performed. The subscriber can view the information one after another by receiving at the frequency f1 of the downlink channel.

The value of the frequency f1 of the downlink channel and other items specific to the communication system may be determined as a standard, or the receiver may automatically search for a frequency band used by the system. It is sometimes recognized.
Alternatively, the information of the item may be obtained through another communication system for automobiles, or the information may be magnetically recorded in a pass certificate received at a gate when entering a motorway, and may be read by a reader of a receiver. be able to. Some items need to be changed for each actual communication system depending on the radio wave usage situation in each region and the policy of the service provider.

As described above, in the section of one subsystem (for example, 21), which base station (21-1 in FIG. 4)
To 21-n), the same downlink signal is transmitted. Therefore, the same frequency (for example, f1) while traveling in that section
Are all receiving the same signal. This is one base station (for example, 21-
1 to 21-n) and a certain vehicle M have a short communication time, only a small amount of data can be transferred during that time, and a downlink signal is prepared for each of a large number of base stations.
This is because the load on the control station 11 becomes too heavy. By transmitting the same downlink signal to the subscriber side from any base station in one subsystem, the control station 11 can support all base stations in the subsystem with one transmitter, and An optical fiber as a broadband communication means used for transmission can also be configured to branch off in the middle as shown in FIG. 5, so that the system configuration is simplified. If the subsystems 21, 22,..., 2k change, the content of the flowing information may be different. Further, if the upstream control stations 11, 12,..., 1m under the control change, the content of the information changes further.

FIG. 6 shows an example of a subscriber radio set installed in a car. The wireless device for a subscriber includes a wireless device main body 71 and a display unit 72. The radio main unit 71 includes a control unit 73 that performs communication with the base station, manages information, and controls the display unit 72, a transmitting and receiving unit 74 that exchanges radio signals with the base station, and a radio signal with the base station. Antenna 75 for transmitting and receiving data, and a memory 76 for storing received information and the like.
And USB (Universal Serial Bus) and IEEE (the I
nstitute of Electrical and Electronic Engineers)
An interface unit (abbreviated as a general-purpose I / F) 78 for connecting a general-purpose computer or a subscriber terminal via a standard I / F such as 1394, and a display unit 72 for displaying information are driven. It is configured to include a display unit driver 77 and the like. When this system spreads, both the display unit 72 and the main body 71 are built into the car from the beginning, and the general-purpose I / F 78 can be installed on the inner wall of the door or on the front or back of the seat, or in a cordless state using optical space transmission. Will be equipped with.

FIG. 7 shows a communication flow in information transmission from the control station to the vehicle. In FIG. 7, the horizontal axis represents time, and the control station with the passage of time. Packets P-1 to P-10 generated from a certain information source are transmitted to the vehicle via the base station with arrows. Is shown. The time section in which the-line indicating the base station is displayed corresponds to the case where the vehicle M
3 is within the communicable range. Packets generated by the control station are successively sent from the base station to the vehicle at the frequency f1. On the subscriber side, when it is within the coverage area of the base station, it receives it one after another. When all of the packets P-1 to P-10 are received, they are reconstructed to reproduce information. Thus, the information provided by the system is transmitted in a packet format. Information composed of a large amount of data is divided into short data by the control station, and each is packetized. As a result, even in a system in which a plurality of vehicles can only intermittently and asynchronously communicate with each other, as in the present wireless communication system, information can be efficiently transmitted by effectively using the time in which each vehicle is in a communicable state. be able to.

FIGS. 8A, 8B and 8C show examples of the structure of an information packet. 8A and 8B show that certain information 90 is divided into ten pieces of data 91, 92, 93,... For transmission, and a header part 111 and an error detection part 113 are added to each data part 112. This shows a state in which packets P-1 to P-10 have been generated. FIG. 8C shows in detail the header part of the packet P-3 among the generated packets P-1 to P-10 (indicated by reference numerals 101, 102,...). “Type” 114 in the header indicates the type of the packet, whether it is broadcast information, addressed to a certain individual, or control information. The "destination" 115 indicates the destination address of the packet. In the case of the broadcast information, the broadcast address is added. "Information I
D "116 is an ID assigned in a state of information before being divided into packets, and is composed of ten packets P-1 to P-10.
Are assigned the same numerical value (00111 in this example), and are managed by the center so that different information does not have the same ID in the entire system. The “total number of packets” 117 is a value (here, 1) indicating how many packets were divided when the information was packetized.
0), the next “sequence” 118 indicates the order (in this case, the third) of the packet.

When a subscriber's radio receives a packet transmitted from a base station and broadcast to each subscriber, it checks whether or not the packet has already been received. A function that stores the packet when it is received, a function that checks whether the original information that forms part of the packet can be reproduced by storing the packet, and a function that reproduces the information In such a case, the function to reproduce the original information and the received packet is duplicated with the already stored packet, or at any other appropriate time, examines the already stored packet and checks the original packet. It has a function of finding a non-arriving packet necessary for reproducing information and transmitting a request signal requesting retransmission of the necessary non-arriving packet to the base station.

The subscriber radio accumulates the received packets. When the original packet can be reproduced from the stored packets and can be provided to the user, it is sequentially transmitted to the user. Notify or display the information. Not all information or all packets constituting certain information are collected during the passage of a vehicle through the communicable range of a base station, but the entire information is received over several base stations.

The subscriber radio transmits the received packet to the
First, it is checked whether there is any overlap with the already stored packet. Further, it is checked whether or not the original information can be reproduced by the received packet. Therefore, FIG.
Regardless of which bucket you look at, the packet is for which subsystem, the state of the whole information (the total number of packets, the contents of the information, the format, the display method, etc.) and the occupation in it Packet header 11 so that its position can be known
1 has a description. Based on the description in the header section 111, the receiver on the vehicle side, that is, the wireless device for the subscriber, arranges and stores the received packets for each information ID, rearranges them, and arranges the necessary packets. Play the original information from the thing.

As will be described later, in order to reliably receive all the packets, the subscriber's radio sets the received packet if it overlaps the already stored packet.
Alternatively, at any other appropriate time, examine the already stored packets, find out the packets necessary to reproduce the original information, and transmit a request signal requesting retransmission of the necessary packets to the base station. Thus, a required packet can be retransmitted from the control station.

As described with reference to FIG. 7, in this communication system, only the intermittent communication between the base station and the car can be performed. On the other hand, a series of information packets is sent unilaterally from the control station. By the way, a vehicle traveling in a section supported by a certain subsystem has neither uniform time to enter the section nor speed at which it passes therethrough. It is totally asynchronous. Therefore, if information is divided into packets and transmitted in the same order, the subscriber side may receive only a part of the packet even if the packet is successfully received. To prevent this, first, it is necessary to limit the total amount of information to be transmitted so that the information is repeated at least a plurality of times even while a high-speed car passes through the subsystem section. That is, the amount of transmission information itself is limited so that all information can be sent in a short transit period. Specifically, the time required to transfer all the information is about three to one-fifth of the total time that the high-speed car is within each communicable range of the time that the high-speed car passes through the subsystem section. Good to be. For example, assuming that there is a vehicle traveling at a maximum of 120 km / h, the vehicle runs through an average base station interval of 100 m in 3 seconds. Assuming that the coverage area of the base station is 30 m in diameter, 1
It takes 0.9 seconds to pass through the communicable range of the base station. Assuming that the number of base stations in the subsystem is 100, the total communicable time in the subsystem is 90 seconds. actually,
Not all of this time can be used for data reception because of the establishment of reception synchronization, but if this point is ignored, 90
It is preferable to limit the total amount to the amount of information that can be transmitted in about 18 to 30 seconds corresponding to one third to one fifth of a second. This time (18
Within 30 seconds), assuming that the information transmission speed is 155 Mbps, this corresponds to an information amount of 350 Mbytes to 580 Mbytes.
Class video will be transferred.

Assuming that the length of one packet is 0.1 second on average, the entire information is about 2 seconds in the above time (18 to 30 seconds).
It will be converted into 00 to 300 packets. The original information is transferred to IP (Inte
rnet Protocol) or ATM (Asy) used in broadband networks
If the packet is provided to the control station in the form of a packet in the form of (nchronous Transfer Mode), the packet length in these formats is at most 0.1 ms at 155 Mbps.
The number of packets further increases.

Then, since these packets are broadcast, utilizing the fact that the destination is the same, if these packets are grouped (grouped) and encapsulated into a longer packet and transferred, The number of packets transmitted by the control station is reduced, and processing for packet management in the control station and the subscriber radio can be reduced.

The control station packetizes the information and repeatedly transmits this packet a plurality of times in the subsystem section. Furthermore, when viewed over a long period of time, it is preferable that the packet transmission order be random within a range of conditions such that all packets are transmitted the same number of times. By randomizing, depending on the speed of the car, the timing at which the car enters the communicable range and the repetition cycle of packet transmission are synchronized,
It is possible to prevent a phenomenon in which the subscriber wireless device receives only the same packet. When the information includes a plurality of packets, the packets are transmitted in a random order and each packet is transmitted a plurality of times. This allows
In addition to preventing the same radio packet from being received by the subscriber's wireless device, it is possible to perform strong communication against burst errors in the information transmission process.

As described above, by designing the packet transmission, even in a high-speed car, a chance to receive each packet in the subsystem is generated a plurality of times, and the same packet is received each time the car enters the communicable range. Is reduced, and all information can be efficiently received while traveling in the subsystem section.

Note that with the above-described means, reception of all packets can still be guaranteed only stochastically. To ensure this, the subscriber radio approaching the exit of the subsystem section can request a packet that has not yet been received if it wishes to receive it. As described above, the header portion of the missing packet can be calculated from the information in the header portion of each packet, and the packet is requested to be retransmitted to the system as personal reception request information. The communication procedure at this time will be described later, but the packet which has not been received is transmitted to the subscriber when the vehicle of the subscriber is within the communicable range of any base station. Then, it is transmitted when the vehicle has passed through the relevant subsystem section and is in the communicable range of the nearest base station even while traveling in another subsystem section. As a result, the subscriber wireless device can efficiently, reliably, and smoothly take in information provided from the control station. Further, since the procedure is designed based on the fastest car, even if the speed of the car becomes abnormally slow due to traffic congestion or the like, all information can be received without any problem. Conversely, the number of cases where the same packet is received a plurality of times increases, so that there is also a problem that transmission efficiency is somewhat deteriorated. For this reason, the system adjusts the total amount of information to be transmitted and the repetition period of the packet based on the maximum speed or average value of the traveling vehicles in the subsystem.

If the vehicle stops in the dead zone, the communication system of the subscriber becomes inoperable in this communication system, so that inter-vehicle communication and other systems (such as a mobile phone system and an ITS integrated system) are not used. And take measures such as obtaining only part of the information via the Internet. That is, on a road, low-speed communication is also provided by other systems such as a mobile phone and a motorway communication system for low-speed communication, and such a system generally has no dead zone. Therefore, even if the vehicle stops at an arbitrary place on the road due to traffic congestion or the like, communication is possible unlike the communication system according to the present invention. By using the communication system according to the present invention in cooperation with such other systems, it is possible to transfer large-capacity and continuous data such as video signals, that is, flow information that requires a wide-band transmission capacity. It becomes possible with a communication system,
That is an important role of this system.

However, in an environment in which communication can be performed only intermittently as in the present communication system, when information packets are transferred randomly as described above, continuous information such as video signals is transmitted to the receiving side ( On the subscriber side), the reproduction is started after giving a delay corresponding to the time in consideration of the rearrangement time in advance. For example, even when a car moves between subsystems or between control stations, data that has already been received is reproduced until packets necessary for reproduction accumulate in the memory unit of the subscriber radio. By doing so, the user can be provided with a good video image by connecting time.

When transferring continuous information such as a video signal, data arrives at the control station one after another from a center or the like. To be grouped together and transferred to the subscriber. In order to perform the transfer with a small delay, the time width for grouping the information is set so that the latest packet group can be received every time the high-speed vehicle passes the base station. Then, within the grouping time, the transmission of the packet group transmitted in the time zone immediately before the time is repeated. The order of packets being repeated is also random. Thus, slightly different from the above example, the packet group can be almost received within the communicable range of one base station in any vehicle, and the received packet changes each time the base station changes. In the control station, it is necessary to determine the transmission cycle in consideration of the speed of the vehicle. Further, the trouble of setting the packet group and the number of times of updating the packet group increase, but the real-time information (real-time type or (Referred to as stream-type information), since information packets collected at certain time intervals are received, real-time information can be provided to the subscriber side in a natural manner. In addition, communication is still possible asynchronously, and necessary packets can be efficiently broadcast to each subscriber irrespective of the movement of the subscriber who enters the dead zone in position.

If the control station has a sufficient processing capacity, it is the same as the real-time information described above, and conversely, the storage-type information (called the store-type or non-real-time information).
Similarly, the grouped transfer methods can be applied. In the case of this grouped transfer, data can be received almost within the communicable range of one base station, and there is no need to store packets over several base stations. Can be reproduced, so that the memory portion of the subscriber radio can be reduced.

In the subscriber radio, the received grouped packet information can be displayed one after another, or the received grouped packet information can be registered in a menu, and the information desired by the user can be viewed. Can also be selected.

When a control station generates a packet from information, it is also possible to process the data in the packet so that each packet contains the entire image of the information. In this case, the subscriber wireless device may sequentially reproduce the received packets and display them. For example, JPEG
In the case of transmitting a still image as in the progressive transmission method in the above, every packet includes information of the entire screen little by little. In this case, if the reproduction is sequentially performed by the subscriber's wireless device, the entire picture is initially blurred and gradually becomes detailed. Depending on the contents of the picture, useful information can be quickly read by the subscriber before the last packet arrives, which is convenient.

Next, an embodiment of a communication flow in the case where request information is transmitted from the center and the control station to the vehicle in response to the request for information from the vehicle will be described with reference to FIG. I do.

In FIG. 9, when a subscriber wants certain information, first, an information request signal is transmitted from the subscriber radio using an uplink control channel. At this time, the subscriber ID is transmitted at the same time. The request signal is received by the control station via the base station A, and the content of the request is transferred to the center. The center prepares the requested information and transfers it to the control station. The information requested by the user may be detailed tourist spot information in the information database of the center, or may be an overseas music video published on the Internet. Alternatively, relay (receive) images from home surveillance cameras via the Internet
You may be trying. Since the center has a gateway that can exchange data with an external network, the center can respond to such a wide range of user requests. The information may be of a finite size that has been stored, or may be a flow of data generated and published in real time. In the case of a finite amount of data such as a storage type, the control station has the information transferred from a center database or the like and stores it in a local streamer attached to the control station. In the case of a real-time data flow, a connection for the data is set up with the center. When the above preparations are completed and the center notifies the end of the information transfer preparation, the control station immediately succeeds in the information request to the subscriber radio through the base station and is ready for the transfer (preparation OK). Is transmitted at the frequency f1. This packet has the frequency f1
Is inserted between the broadcast information of the downlink channels. The subscriber wireless device that has received the notification of preparation OK sends a packet (reception enable signal) indicating that information can be received, and urges the control station to transfer request information through the base station. In response to this reception enable signal, the transfer of the information packet from the control station to the car (subscriber) is started via the base station.

When the vehicle enters the communicable range of a base station, the subscriber radio transmits a reception enable signal after waiting for a random time, when the reception enable signal and the information transfer timing from the control station are transmitted. It is also possible. In some cases, the vehicle may not know the distance to the base station or whether communication with the base station is possible, or it may take time to make the determination. If the car is moving at a high speed and the judgment takes a long time, communication may be possible before the judgment, but communication may not be possible after the judgment. In consideration of this, as shown in () in the figure, after receiving a packet indicating that the vehicle is ready for transfer from the base station (preparation OK), whether or not communication with the base station is possible is determined. Without knowing
Immediately or after waiting for a random time, it is also possible to intermittently transmit a plurality of reception enable signals at predetermined intervals or at intervals calculated according to a predetermined randomization method. It is possible. At this time, the subscriber ID is transmitted simultaneously with the reception enable signal. When a system configuration in which collision of uplink signals is unlikely to occur as described later is employed, there is no need to wait at random time.

Here, the frequency allocation used in the present radio communication system, the signal contents of the channels used for the uplink and the downlink of the present system, and the radio section of the subscriber radio will be described.

FIG. 10 shows an example of frequency allocation used in the present radio communication system. In this example, the same frequency channel is used for the downlink (base station → subscriber) and the uplink (subscriber → base station), and TDD (Time Div.
ision Duplex) system is shown. A control channel and a communication channel are provided in the system band. Regarding communication channels, a common information communication channel that regularly transmits information that is common to many vehicles, such as road information, and a custom information communication that transmits information in response to subscriber requests from vehicles And a communication channel. Here, a case is shown in which two channels are provided as common information communication channels and five channels are provided as custom information communication channels.

FIG. 11 shows an example of signal bursts of a control channel and a communication channel when the TDD system is used in the wireless communication system. Downstream of the control channel is a burst for synchronization, source ID, a control information area, and a tail bit. Upstream of the control channel is a contention area. The downlink of the communication channel for common information includes a synchronization burst, a calling ID, a common information area, and a tail bit, and the upstream of the channel includes a contention area. The downlink of the communication channel for custom information includes a burst for synchronization, a calling ID, a custom information area, and a tail bit, and the upstream of the channel includes a contention area.

The feature of the signal burst shown in FIG. 11 is that the base station always adds a unique base station source ID on the downlink channel, so that when the vehicle receives the downlink channel, the vehicle can reduce its own speed. Taking into account that the car can determine the communication partner (base station) and the size of the uplink traffic, the uplink time rate of the control channel and the custom information communication channel is determined, and the common information communication is determined. To reduce the rate of the upstream of the service channel,
Alternatively, in some cases, resource allocation is optimized by eliminating upstream time, and for each upstream channel, almost all contention areas are used for packet communication systems such as Aloha. is there. In addition, the Aloha method means that when a plurality of subscribers can freely transmit an upstream signal and the upstream signal from the plurality of subscribers causes a collision in the upstream line, the upstream transmission from the next plurality of subscribers is performed. The signal is transmitted at a timing in which each subscriber sets a waiting time at random, thereby reducing the probability of the next uplink collision occurring.

FIG. 12 shows an example of an upstream contention area in FIG. Regarding the contention area in the control channel, there are respective burst configurations of Nos. 1 and 2 depending on the situation where the car (subscriber) is located. In the first case, the communication device includes a burst for synchronization, a calling ID, vehicle speed information, a request channel assignment request (or a communication channel assignment request), and a tail bit.
, A synchronization burst, a source ID, vehicle speed information, the content of an information request (including a priority request), and a tail bit.

Similarly, regarding the contention area in the communication channel for common information or the communication for custom information, depending on the situation where the car (subscriber) is located, the content of the first, second, third, etc. Each has a burst configuration. In the first case, the burst for synchronization, the source ID, the vehicle speed information,
Information request content (including priority request),
Part 2 includes a burst for synchronization, source ID, vehicle speed information, information to be transmitted, and tail bits. Part 3 includes a burst for synchronization, source ID, vehicle speed information, and request information reception. And a tail bit.

The feature of the contention burst shown in FIG. 12 is that, in each case, by adding a unique car ID and vehicle speed information to each car, the car (subscriber) who is moving can be intermittently operated. Control at the control station specific to the communication system that communicates in a simplified manner, and the control channel includes a request communication channel or control channel allocation request, or a general communication channel. A format for making an allocation request or notifying the content of the information request (and, in some cases, specifying the priority of the request) is provided. In the communication channel, the content of the information request is notified (in some cases, Sends the format and general communication contents that also specify the priority of the request) Formats, further providing a format for notifying that the request information is receivable state is.

FIG. 13 shows an example of the radio section of the subscriber radio in the case of the TDD system. The radio unit includes an antenna, an antenna switch, a receiving circuit, and a transmitting circuit. The receiving circuit includes an RF amplifier, a bandpass filter (B
PF-1), first mixer, local oscillator (RFLO), bandpass filter (BPF-2), IF amplifier, second mixer, local oscillator (IFLO), baseband demodulator (BB demodulator), not shown It is composed of a digital circuit including an interface with a signal processing unit. The transmission circuit includes a digital circuit, a baseband signal generator (BB signal generator), a modulator, a local oscillator (IFLO), a bandpass filter (BPF-3), a buffer amplifier, a transmission mixer, a local oscillator (RFLO), It comprises a bandpass filter (BPF-4) and a power amplifier.

In the radio section of the DD system shown in FIG. 13, since the same frequency is used for transmission and reception, the frequency of the local oscillator (RFLO) of the high frequency part and the local oscillator (IFLO) of the intermediate frequency part are set to the transmission circuit side. This can be shared by the receiving circuit side, it is difficult to cause interference between the operations of the transmitting circuit and the receiving circuit, and the size of the radio unit can be reduced. Also, by providing a synthesizer in IFLO, RF
It is also possible to configure a wireless unit that is less expensive than making the LO variable.

FIG. 14 shows another example of the frequency allocation used in the present radio communication system. In this example, the downlink (base station →
FD that uses different frequency channels for the subscriber) and uplink (subscriber → base station) and performs duplex communication by frequency division
This is an example in which a D (Frequency Division Duplex) system is adopted. Similar to TDD, a control channel and a communication channel are provided in the system band. The communication channel includes a common information communication channel for transmitting information that has a common request in many vehicles such as road information on a regular basis. A custom information communication channel for transmitting information in response to a subscriber request from a car. In addition, since the amount of information is generally smaller in the uplink than in the downlink, it is possible to narrow the uplink communication channel, improve the frequency efficiency, and reduce the cost of the radio transmitter mounted on the car. . Also, the downlink control channel fCN
By selecting the difference between the TLDN and the frequency fCNTLUP of the uplink control channel to be the optimum frequency for the reception IF frequency of the radio section of the subscriber radio, the subscriber radio in the case of the FDD system shown in FIGS. As shown in the example of the radio section of the
The frequency of FLO or IFLO can be commonly used for transmission and reception, and the wireless transmission unit mounted on the vehicle can be configured at low cost.
FIG. 15 shows an example of the FDD radio unit of the double conversion system, and FIG. 16 shows an example of the FDD radio unit of the single conversion system.

FIG. 17 and FIG. 18 show F
An example of signal bursts of a control channel and a communication channel (common information communication channel and custom information communication channel) in the case of using the DD system is shown. The characteristics of the signal burst are almost the same as in the case of TDD. For each of the downlink channels of the control channel and the communication channel, as shown in FIG. By adding
The car judges its own speed, or the car is the communication partner (base station)
Can be confirmed, and the respective up channels of the control channel and the communication channel are shown in FIG.
As shown in (1), the contention area is almost used for a packet communication system such as Aloha.

Here, description will be made returning to FIG. 9 again. After receiving a packet indicating that the car (subscriber) is ready for information transfer from the base station (preparation OK), it sends out a receivable signal within 0.2 seconds after entering the communicable range. Upon completion, the control station immediately allocates a bandwidth for the subscriber in the downlink and packetizes and transfers the information. In this 0.2 second, the car exits the communicable range in a minimum of 0.9 seconds, while the control station obtains a reception enable signal, changes the packet transmission order, and transmits the packet addressed to the subscriber. Since it takes into account that it takes about 0.1 to 0.2 seconds of processing time to send the data to the unit, the time is different in a system having different times.

As shown in FIG. 9, the subscriber receives a packet of information from the same base station that sent the ready signal. If the packet is successfully received and the information consists of one packet, the transfer is completed. In addition, even if the reception enable signal is transmitted, if a packet is not obtained within the communicable range with the base station, if the packet enters the communicable range with the next base station, the above-described processing is performed again. In the same manner, a reception enable signal is transmitted to try to receive a packet. It is needless to say that the subscriber ID is transmitted simultaneously with the reception enable signal.

Next, a description will be given of a function of estimating the moving state of a subscriber and determining one or a plurality of base stations which are considered to pass within a predetermined time.

In connection with the above-mentioned matter, after receiving a packet indicating that the vehicle (subscriber) is ready for information transfer from the base station (preparation OK), it is preferable to transmit a reception enable signal. If the delay is longer than 0.2 seconds, the subscriber I
It is also possible to include the value of the traveling speed in addition to D and to specify that a packet is received in the next or subsequent communication with a plurality of base stations. In this case, the control station calculates the timing at which the vehicle enters the communicable range with the next base station based on the traveling speed, so that the control station has a margin for preparing to insert the packet into the downlink signal in accordance with the calculated value. Can be carried with you. Depending on the surrounding situation, the intervals between the base stations may not be uniform, but in this case,
The control station multiplexes information that counts the number of communicable areas that have passed since the subscriber entered the subsystem into the receivable signal. The calculation of the timing of entering can be performed more accurately.

Alternatively, in the case where the control system is constructed in the subsystem so that the received uplink signal can be separated independently for each base station, the reception enable signal (subscriber ID and running (Including the value of the speed) is sent, and the timing at which the vehicle enters the communicable range with the next base station can be calculated.

Further, it is conceivable that one base station supports communication in both directions on a one-lane opposite road, etc. Can be notified to the control station.

As described above, a control station, subsystem, or base station suitable for transmitting a downlink signal to be transmitted to a subscriber is determined based on an uplink signal from the subscriber, and prepared from the determined system part. By enabling the transmission of the radio signal, the time from the reception of the uplink signal to the transmission of the downlink signal in the system part can be independent of the time when the subscriber passes through the coverage area of one base station (independently). For example, it is possible to set the time to pass through the next or subsequent multiple base stations. Therefore, even when it takes time to prepare downlink signals at the control station, when subscribers move between subsystems and control stations, and when the communicable range per base station is narrow, efficient and smooth subscription Information transfer to the party is performed.

As described above, by transmitting a packet of information from the control station to the subscriber under the initiative of the subscriber based on the reception enable signal from the subscriber side, the control station side There is no need to manage the movement of vehicles that are within the service range of the system. Even in an environment where communication can be performed only intermittently, such as this wireless communication system,
There is an advantage that communication can be performed without imposing a burden on the control station.

When the requested information is transferred to the subscriber in a plurality of packets, the packet is transmitted from the control station in advance to notify the preparation for transfer OK or from the first received packet among the plurality of packets, The subscriber can recognize the total number of transferred packets (see reference numeral 117 in FIG. 8). The subscriber side repeatedly transmits the reception enable signal until all the packets are collected. As shown in FIG. 9, the control station can also continuously transmit a plurality of information packets to the car in response to one reception enable signal from the subscriber side. For example, when a subscriber enters a communicable range of a base station into a wireless device for a subscriber (the fact that the subscriber has entered the communicable range means that the frequency f1 broadcast from the system side is always down as described above). A function to measure the time from receiving the channel signal is provided. Based on the function, the remaining time available for communication with the base station is estimated, and the remaining time or reception within the time is estimated. The number of possible packets is calculated, and the number of packets is notified to the control station together with the reception enable signal. Thus, the control station can continuously transmit a plurality of packets to the vehicle in response to one reception enable signal. As a result, a plurality of packets can be continuously received as compared with the case where the packets are transferred one by one every time a reception enable signal is received, so that the reception is completed quickly. Therefore, the number of transmissions of the receivable signal from the subscriber side is reduced, and information transfer from the control station is also efficient, which ultimately leads to a significant reduction in information transfer time. If the estimation of the time to get out of the communication range is incorrect or a packet that could not be received due to a communication error occurs, send a reception enable signal requesting retransmission of the packet to the control station, and specify it. It is also possible to have them retransmitted on a regular basis.

Next, a function of specifying a packet to be received again and retransmitting the packet will be described. Packet retransmission is also performed by the subscriber requesting retransmission. As mentioned above,
The subscriber wireless device accumulates packets more and more until the original information of the received packet can be reproduced. Among them, it finds a missing packet and requests retransmission, but since the packet is sent at random, if the sequence number skips, as in the existing protocol, retransmit the packet with the missing sequence number. The method of requesting cannot be used. Therefore, as another means, the subscriber wireless device according to the present invention has a function of storing the number of receptions of each received packet. As a result, if it is frequent to receive already received packets even though all the packets have not been received yet, it is known that unreceived packets have already failed to be received for some reason. The ID and the sequence number are added to the reception enable signal to notify the control station. The control station specifies a packet that the subscriber wants to receive again from the reception enable signal, and retransmits it to the subscriber again. For example, during reception of information consisting of 10 packets, if packets other than the packet of sequence number 7 have been received and two of them have already been received three times, the packet of sequence number 7 will be Since it can be determined that reception is difficult, the subscriber's radio requests retransmission of the packet.

Alternatively, a timer may be used to request a retransmission of a packet that has not been received within a preset time, or a time required to exit the subsystem may be estimated, and a packet that has not been received before a certain time has elapsed. A retransmission request may be made. In these cases, it is not necessary to store the number of packet receptions, but it is necessary to set a timer.

Next, the handling of the data held by the control station will be described. The control station repeats the transfer or retransmission of the packet according to the content of the reception enable signal from the subscriber side. The data on the control station side after the reception enable signal no longer arrives and after a predetermined time by the timer measurement is sequentially discarded. Alternatively, if the subscriber has transmitted a signal other than the reception enabled signal, it is possible to determine that the communication using the reception enabled signal has succeeded without any problem without any time, and the data is discarded.

Next, the operation of the local streamer provided in the control station will be described.

The local streamer provided in the control station has a function of accumulating a part of the information provided in the area where the base station accommodated by the control station is present and updating the information as necessary. Request signal from subscriber and subscriber ID
And, if necessary, to another control station in the direction of movement of the subscriber, the information request signal and the I
Notify D. The control station or the notified control station interprets the information request signal, and determines whether or not the information requested by the information request signal exists in the local streamer connected to the control station, and It is determined whether or not the content exists in the provided center database.If the content does not exist in the local streamer and exists in the center database, the request is made using the network between the center and the control station. It has a function to download information from the center.

Data that has been transferred from the control station is not always discarded by the control station as it is, and frequently requested information is stored in a local streamer provided in the control station. Thus, when a request for the same information comes from another subscriber, the control station can respond to the request without sending the request content to the center. Billing /
Due to policy or other reasons, the center may be notified only of the request and responded to the request after receiving permission from the center. There is an advantage that transfer is reduced.

[0086] Of these pieces of information stored in the local streamer, some of which are frequently updated may be periodically or according to a pre-scheduled schedule. By downloading the update information from the center in a time when there is relatively little trouble and there is no problem, the latest data is always stored in the local streamer. By using the local streamer in this way, instead of downloading from the center each time a subscriber's request is made, it is possible to determine when traffic between the center and control station network is relatively small and there is no problem. It can be downloaded from the center, so that the communication line can be effectively used.

Further, the above-described function of predicting the moving state of the subscriber allows the subscriber who moves the control station or the like to transmit the requested information between the base station and the control station and between the control station and the control station. In cooperation, there is an effect that communication can be continuously and smoothly provided.

The control station also effectively utilizes the local streamer when transferring information flowing in real time. In this case, every time the car enters the communicable range, the subscriber sends out a reception enable signal, and the control station sends out information packets one after another within a communicable time toward the car. The information is stored in the local streamer during the time when the subscriber enters a dead zone or the like and cannot communicate. When the car comes within the communication range with the next base station, a reception enable signal is sent to the control station again, and the control station sends the stored information and the information delivered in real time to the subscriber. Send to. Furthermore, by combining the reception enable signal with the running speed and the scheduled time deviating from the communicable range each time, the control station stores the time from the time at which the vehicle is estimated to be communicable at the next base station. The information and the information transferred from the center in real time are sequentially sent to the subscriber. In particular, if there is no response from the subscriber, the transfer is considered successful. After transmission, the stored information is deleted if there is no problem after a certain period of time. After transmitting all the packets relating to the information, the control station terminates the transfer if the subscriber does not receive a reception enable signal for a certain period of time or receives a request end signal from the subscriber. At the same time, the information remaining in the local streamer is discarded.

In this radio communication system, as shown in FIG. 9, the subscriber transmits a signal confirming that information has been received to the control station so that the uplink capacity and reliability do not need to be very large. We have mainly described examples of designs that do not. Therefore, in consideration of such points, when the subscriber receives the request information from the control station, the subscriber can transmit a request end signal. When the request end signal is sent in this manner, the control station can delete the transferred information packet from the local streamer without waiting for a predetermined time to elapse by timer measurement. This is effective for efficient use of the capacity of the local streamer.

In some cases, a group travels by sharing several cars, or while several trucks are connected to the site while traveling to the site, the same information may be broadcast to all the cars in the group. This will be described with reference to FIG.

As shown in FIG. 19, the control station receiving the request signal having such a request transfers the request to the center as a broadcast request. The center transfers the requested information to the control station and notifies the end of preparation for information transfer. The control station inserts the information packet into the downlink this time without notifying each vehicle of the preparation OK. The control station does not request a reception enable signal or acknowledgment from each vehicle, and the control station repeats each information packet several times at random so that each vehicle can receive it. Each car is
When a packet that cannot be received is detected, retransmission is individually requested. Thereby, in the present wireless communication system, even in a situation in which a part of the vehicles belonging to the group can communicate and the rest must be broadcast in a state where communication is not possible,
Broadcasting of information can be realized efficiently.

As described above, each subscriber can generate an uplink signal at an arbitrary timing by using an Aloha system as an access protocol of an uplink from a subscriber side to a control station. If there is no response from the control station within a certain period of time, the subscriber radio determines that the uplink signal could not be received by the control station due to signal collision or the shadow of a car, and retransmitted. Perform Since the uplink is multiplexed for each subsystem, signal collision does not necessarily occur only between vehicles accessing the same base station. For example, an upstream signal packet transmitted by the vehicle 1 within the communicable range of the base station b is multiplexed with upstream signals of the base stations c, d,... When transmitted to the control station. If the base station f sends an up signal from another car 2,
If sent at the same time as
The two upstream signals collide and become unreceivable at the control station,
Not accepted.

Means (1-7) for avoiding collision of upstream signals from a plurality of subscribers will be described.

In the first means, when a subscriber retransmits an uplink signal, the time from the previous transmission to the retransmission is set to be randomly changed, and the time becomes longer as retransmission is repeated. Is set to be longer.
As a result, when the uplink signals of two vehicles collide at a certain timing, the probability of collision when the retransmission is performed next is reduced, or even when retransmission is performed when the uplink is busy, the retransmission request signal is Reduces the probability of congestion. This is because, for example, traffic congested, the number of vehicles parked within the communicable range of each base station increased, the demand for information transfer services also increased, and even in situations where a large number of request signals were generated, the minimum throughput It is effective in providing.

The second means is to set the frequency of the local oscillator OSC2 in the uplink signal circuit in the base station shown in FIG. 5 to a different value for each base station and to change the frequency for down-converting the uplink signal. It is possible for the upstream control station to distinguish and receive the uplink signal from each base station. In this case, the collision of the uplink signal occurs only between the subscribers within the communicable range of the same base station among the plurality of base stations, so that the probability of occurrence of the collision is reduced.

The third means uses a slotted Aloha system or the like which is an improvement of the Aloha system, thereby obtaining an effect of suppressing a decrease in communication efficiency due to collision of uplink signals. This is to set the waiting time randomly by each subscriber, but to transmit the uplink signal only in the time slot provided at fixed time intervals, and to align them with the time slot when colliding Thus, the probability that a plurality of uplink signals collide during transmission of one uplink signal can be reduced, and communication efficiency can be increased. In this case, the slot synchronization signal should be generated at the control station and distributed to each subscriber through a broadcast channel of frequency f1.

In the fourth means, depending on the modulation / demodulation method used in the radio unit, unfairness may occur depending on the distance between each subscriber and the base station. This can be avoided by applying a method of providing a time slot for competing for uplink access used in two-way data communication of a cable television system or the like. In this scheme, in the time slot, each subscriber transmits a signal indicating a request to access the uplink, for example, a very short pulse. Since short pulses hardly overlap each other, the control station can detect collision of an access request to the upstream if there are a plurality of short pulses, and broadcast it via a downlink signal. If the subscriber who issued the uplink access request receives the notification that the uplink access request has collided, waits for a random time and then issues the uplink access request again, then each subscriber's uplink access request can collide The control station issues a transmission permission via a downlink signal if there is no collision, and the subscriber can transmit a signal to the uplink. By this means, a fair uplink access can be realized, but in the present communication system in which communication can be performed only intermittently, the interval of setting the time slot for performing the access competition is further increased considerably, May be randomized so that any subscriber can meet the access competition throttle while in the coverage area with a sufficiently short waiting period.

The fifth means is a case where each base station receives an uplink signal to perform a carrier sense type collision avoidance control. Each base station partially branches the signal from the upstream fiber, receives the upstream signal channel coming from the downstream side, and compares it with the upstream signal channel received by the antenna at the base station to detect a collision. If a collision is detected, the base station stops and discards the uplink signal received by the antenna at the base station according to a preset probability, and gives priority to the uplink signal coming from the downstream side, or conversely, from the downstream side. The incoming uplink signal is stopped, and the uplink signal received by the antenna at the base station is preferentially transmitted to the control station. As a result, even when an upstream request is in collision, it is possible to process the upstream request fairly and efficiently without any particular advantage of the downstream upstream signal or the upstream upstream signal.

As means for stopping the upstream signal from the downstream, as shown in FIG. 20A, when there is only a common upstream signal channel where the collision occurs in the upstream fiber 70-2, the upstream fiber 70-2 is used. Partially split the optical signal,
An upstream signal channel from the downstream side is detected by the optical receiver RX, and this detection signal is compared with the upstream signal channel received by the antenna 66 of the base station 21 and the millimeter wave receiver RX1 by the comparator COM to determine the collision. To detect. If a collision is detected, a process of turning off the upstream line by the upstream fiber 70-2 while keeping the optical signal level using the optical switch SWP is performed. Alternatively, as shown in FIG. 20 (b), a regenerative relay comprising an optical receiver RX (conversion from light to electricity) and an optical transmitter TX (conversion from electricity to light) is provided on the upstream line by the upstream fiber 70-2. And an electrical switch SW between the optical receiver RX and the optical transmitter TX in the regenerative relay system.
Performing a process of turning off in the state of an electric signal through E
This can be achieved by:

When there are a plurality of upstream channels in the upstream fiber 70-2, the upstream line is connected to an optical receiver and an optical receiver so that upstream channel signals irrelevant to the occurrence of collision coming from the downstream can be distinguished and relayed. It is electrically separated into a regenerative relay system by the transmitter, and only the channel where a collision occurs is subjected to the above-described switching processing, unrelated channels are passed through as they are, and these are multiplexed again and transmitted. When the base station optically multiplexes the uplink signal received by the antenna at the local station on the uplink so that the uplink signal can be distinguished from the uplink channel signal coming from the downstream, the level is sufficiently increased to multiplex to avoid collision. realizable.

The optical signal branching from the upstream fiber for performing the collision avoidance control by the fifth means complicates the configuration of the base station and the optical level design of the uplink. Alternatively, the configuration and design are similarly complicated when a regenerative relay system is used.

As a sixth means, to avoid this,
The control station or the most upstream base station (that is, the base station closest to the control station) electrically or optically folds the uplink signal and retransmits the uplink signal to all base stations via the downstream fiber to thereby transmit the uplink signal. It performs detection. However, in this case, there is a delay for call back,
In addition, the timing and the format of the packet need to be designed so as to avoid collision. For example, it is necessary to design such that a sufficient guard time is required from the transmission of an uplink signal to the detection of a collision, or that a packet has a sufficiently long redundant portion.

Further, a seventh means is to provide a function of delaying a packet to the base station in order to utilize both uplink signals when the collision of the uplink signal is detected. When detecting a collision, the base station temporarily stores the uplink signal received by the local station in the function of delaying the packet, and multiplexes the packet to the uplink after the signal flowing through the uplink disappears. As a result, without the delay function, both uplink signals that could not be received by the control station due to collision either reach the control station, and the uplink can be used more efficiently.

Next, a description will be given of how the system responds to traffic jams of vehicles (subscribers). In terms of congestion, the absolute number of subscribers for each base station or each subsystem increases, so individual service requests arising therefrom also increase, but the downlink capacity due to restrictions on downlink fibers and wireless lines changes. Absent. For this reason, a situation where all service requests cannot be satisfied in terms of transmission capacity is likely to occur. In order to avoid such service degradation and unfairness due to lack of capacity, during traffic jams, the system side does not accept personal information requests, or limits the downlink bandwidth allocated to each request, Instead, increase the content of the broadcast information. For example, "distribution of all individually requested movies is refused, and only a few types of movies usually provided for a fee are broadcast free of charge." Instead of not being able to meet the demands of the individual users, the system provides special services to reduce user dissatisfaction and avoid overloading the system.

The wireless communication system according to the present invention is a system in which a subscriber and a center mainly communicate via a control station. However, the subscriber may request information from outside the system or communication with the outside of the system. In this case, the system provides the subscriber with a standard communication interface, for example an ATM (Asynchronous T).
(ransfer Mode) connection or IP (Internet Protocol) connection. For this reason, in the present system, the packet from the subscriber on the uplink is terminated by the control station, and the content of the packet is a command peculiar to the present system or other types of IP packets and ATM cells. Commands are distinguished. Then, the data is sent to the center through a virtual logical connection corresponding to each case. For example, between the control station and the center, a logical channel used for the IP connection used in the Internet is set on the network between the center and the control station, and the content of the upstream signal from the subscriber is in IP format. , The IP packet is transferred to the center via the logical channel. On the center side, the output of this virtual logical channel is connected to a router, which forwards the IP packet towards its destination. At this time, the control station updates a database that associates the ID of the subscriber with the source IP address of the IP packet sent by the subscriber, and transmits the IP packet transferred in the downstream direction to the control station-subscriber communication. Can be converted to packets for The router installed at the center also updates the routing table indicating to which control station the IP packet coming from the outside should be routed. Each time a subscriber crosses between subsystems / control stations as it moves,
Will be updated.

With this function, a logical channel corresponding to the standard service can be formed on the communication path from the control station to the subscriber, and the radio communication system can be treated as a link device from the upper layer. On the other hand, processing specialized for higher layers, such as termination of the TCP protocol at the control station, is not performed.

By providing the control station with a commonly used standard network layer interface such as IP or ATM, the processing on the center side can be reduced more than the control station. The wireless communication unit between the subscriber and the base station in the present system is a unique physical layer unit that behaves in a manner not assumed by the standard service. And the special processing for that purpose, especially the part where the data transfer in the down direction can be smoothly performed under the control of the subscriber side, the passage of data in time and distance is as short as possible. Therefore, even if the same higher-level protocol used by the above-mentioned standard services such as IP and ATM on other systems is used as it is in this wireless system, almost no problem occurs. Further, the present system need not individually cope with various existing or newly created higher-level protocols. Also, not all interfaces are processed in the control station.
Signaling of ATM services and network layer services that are rarely used are transferred to the center by a unique communication method between the control station and the center used for system-specific command transfer, and processed by the center. Thus, a channel for the service is set in the network between the center and the control station, and the exit is created in the control station. Therefore, the load on the control station does not become extremely heavy for multi-service providing various standard services and packet distribution of the services.

When large-volume information or real-time information is requested and transferred, communication does not end in one subnet, and the next is received in the next subnet. In this case, the reception frequency changes, and the switching of the information transfer destination from the center and the timing of the switching are required. When transferring between subsystems managed by the same control station, the control station manages the transfer.When transferring between subsystems belonging to different control stations, the transfer of the transfer is performed between the related control stations according to the instruction of the center. Management.

When a wide-band communication means such as an optical fiber has a limited distance due to the influence of distortion, noise, etc., as in the other embodiment of the wireless communication system of the present invention shown in FIG. Along the road from the control station 1001, a plurality of broadband communication means 10
By extending 02, the number of control stations 1001 in the entire wireless communication system can be reduced.

In the above embodiment, an example of a system in which all base stations in a certain subsystem transmit substantially the same downlink radio signal has been described. The present invention has the same effect in a system in which a channel for transmitting a downlink signal dedicated to each base station is included in the downlink signal.

[0110]

As described above, according to the present invention, the apparatus on the subscriber side can control the data transfer from the system side, and the system side can control between the base station and the control station and between the control station and the control station. In a system where communication can be performed only intermittently, the control station or center does not need to accurately grasp the position and communication state of each subscriber, thereby enabling efficient communication. Thus, smooth and reliable communication can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a wireless communication system according to the present invention.

FIG. 2 is a diagram showing an example of a center configuration in FIG. 1;

FIG. 3 is a diagram showing a configuration example of a control station in FIG. 1;

FIG. 4 is a diagram showing an example of a subsystem in FIG. 1;

FIG. 5 is a diagram showing a configuration example of a base station in FIG. 1;

FIG. 6 is a diagram showing a configuration example of a communication device on the subscriber side in FIG. 1;

FIG. 7 is a diagram showing a communication flow in the first embodiment.

FIG. 8 is a diagram showing an example of the structure of an information packet.

FIG. 9 is a diagram showing a second embodiment of a communication flow in a case where request information is transmitted from a center and a control station to a vehicle in response to an information request from the vehicle.

FIG. 10 is a diagram showing an example of a frequency arrangement used in the wireless communication system.

FIG. 11 is a diagram illustrating an example of signal bursts of a control channel and a communication channel when the TDD scheme is used in the wireless communication system.

FIG. 12 is a diagram showing an example of an upstream contention area in FIG. 11;

FIG. 13 is a diagram showing an example of a radio unit of a subscriber radio in the case of a TDD system.

FIG. 14 is a diagram showing another example of the frequency allocation used in the wireless communication system.

FIG. 15 is a diagram showing an example of a radio unit of a subscriber radio in the case of an FDD system.

FIG. 16 is a diagram showing another example of the radio unit of the subscriber radio in the case of the FDD system.

FIG. 17 is a diagram showing an example of signal bursts of a control channel and a communication channel when the FDD scheme is used.

FIG. 18 is a diagram showing an example of signal bursts of a control channel and a communication channel when the FDD scheme is used.

FIG. 19 is a diagram showing a third embodiment of a communication flow when transmitting an information packet from the center and the control station to the vehicle in response to a broadcast request from the vehicle.

FIG. 20 is a diagram showing a means for stopping an upstream signal from a downstream.

FIG. 21 is a diagram showing another embodiment of the wireless communication system of the present invention.

[Explanation of symbols]

1 ... center, 2 ... center-control station network, 11-1 m
... Control stations, 21-1 to 21-n, 22-1 to 22-n,
2k-1 to 2kn base station, 31 to 3k broadband communication means, 43, 44 center database, 54 local streamer, 70-1 down fiber, 70-2 ...
Uplink fiber, 71: Radio unit, 1001: Control station,
1002 Broadband communication means.

Claims (7)

[Claims] 1. A center for controlling an entire radio communication system, a base station for transmitting and receiving radio signals to and from a moving subscriber, and a plurality of base stations accommodated by broadband communication means such as optical fibers for transmitting and receiving information signals. In a wireless communication system having a control station to perform and a network between a center and a control station connecting the center and the control station, when the control station transmits information to a specific subscriber via the base station, A wireless communication system, wherein the subscriber notifies a control station using a signal indicating that reception is possible, and the control station that has received the reception enable notification transfers the information to the subscriber. 2. A communication device having a function of detecting that a subscriber has entered a communicable range of a base station, wherein the subscriber transmits a signal indicating that reception is possible, based on the fact that the subscriber has a communicable range of the base station. 2. The wireless communication system according to claim 1, wherein the wireless communication system is performed based on a timing at which it is detected that the intrusion has occurred. 3. A center for controlling the entire radio communication system, a base station for transmitting and receiving radio signals to and from a moving subscriber, and a plurality of base stations accommodated by broadband communication means such as optical fibers for transmitting and receiving information signals. In a wireless communication system having a control station for performing communication and a network between a center and a control station connecting the center and the control station, the control station converts information requested by an information request signal from a subscriber into a wireless signal. On the other hand, receiving the ID and the value of the traveling speed of the subscriber intermittently transmitted using the uplink channel from the subscriber, one or more of which is predicted that the subscriber will pass in the vicinity thereof within a predetermined time. A wireless communication system having a function of determining a plurality of base stations and transferring the wireless signal through the determined base stations. 4. A center for controlling the entire radio communication system, a base station for transmitting and receiving radio signals to and from a moving subscriber, and a plurality of base stations accommodated by broadband communication means such as optical fibers for transmitting and receiving information signals. A subscriber station used by a subscriber in a wireless communication system having a control station for performing communication and a center-control station network connecting the center and the control station, comprising: an information request signal for the base station; Immediately after receiving a signal indicating completion of transfer preparation from the base station, or immediately after a predetermined period of time, using the uplink channel of the wireless communication system. Signal intermittently transmitting the signal indicating the subscriber ID and the ID of the subscriber, and having the information requested using the downlink channel of the wireless communication system. For a radio telephone subscriber, characterized in that it comprises a receiving functions. 5. A center for controlling the entire radio communication system, a base station for transmitting and receiving radio signals to and from a moving subscriber, and a plurality of base stations accommodated by broadband communication means such as an optical fiber for transmitting and receiving information signals. In a wireless communication system having a control station to perform and a network between a center and a control station connecting the center and the control station, the control station is intended for a series of base stations accommodated by a certain broadband communication means. For the information signal broadcast by the control station to a plurality of subscribers within the service range, the control station has a function of packetizing the information signal and transmitting the information signal multiple times, or when the information signal becomes a plurality of packets. Further has a function of transmitting the packets in a random order and transmitting each packet a plurality of times. 6. A center for controlling the entire radio communication system, a base station for transmitting and receiving radio signals to and from a moving subscriber, and a plurality of base stations accommodated by broadband communication means such as optical fibers for transmitting and receiving information signals. A radio station for use by a subscriber in a radio communication system having a network between a center and a control station for connecting the center and the control station. When receiving a broadcast packet, a function for checking whether the packet is already received, and a function for storing the packet when the packet is received for the first time;
A function of checking whether or not the original information forming a part of the packet can be reproduced by storing the packet; and a function of reproducing the original information if the information can be reproduced. If the received packet overlaps with the already stored packet, or at any other appropriate time, it examines the already stored packet and finds the non-arriving packet necessary to reproduce the original information, A wireless device for a subscriber, comprising a function of transmitting a request signal for requesting retransmission of the required non-arriving packet to the base station. 7. A center for controlling the whole radio communication system, a base station for transmitting and receiving radio signals to and from a moving subscriber, and a plurality of base stations accommodated by broadband communication means such as optical fibers for transmitting and receiving information signals. In a wireless communication system having a control station to perform and a network between a center and a control station connecting a center and a control station, a local streamer is provided in the control station, and the local streamer is a base station accommodated by the control station. Has a function of accumulating a part of information provided in an existing area and updating the information as necessary. The control station receives an information request signal from the subscriber and the ID of the subscriber, and Sends the information request signal and the ID of the subscriber to another control station existing in the moving direction of the subscriber, and the control station or the notified control station transmits the information request And interprets whether the information requested by the information request signal is in the local streamer connected to the control station or not and in the center database, and determines whether the information is present in the local streamer. A wireless communication system having a function of downloading requested information from a center using a network between a center and a control station when the content exists in a center database.