JP2002164833A - Seamless communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seamless communication system which allows the shortening of broadcast data communication disconnect time in switching a communication region, easy embodiment of the major part of circuit through control logic or software processing, downsizing of vehicle-mounted terminals, and the limitation, of a overlap zone between adjacent communication-regions such that a communication frame period, a broadcast data update timing, and a maximum speed of a terminal-mounted vehicle are taken into account, such as comparatively facilitates a placement design of roadside-units. SOLUTION: In this seamless communication system between a road and a vehicle in a series of limited communication regions, a vehicle-mounted terminal performs a frequency-switching at a zone for switching of communication region and seamlessly receives broad cast data, divided into several frames, supplied from a roadside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous communication system in a wireless information communication system between a road and a vehicle in a continuous narrow communication area.

[0002]

2. Description of the Related Art The state of communication at a communication area switching point of an in-vehicle terminal device moving in a continuous narrow area as shown in FIG. 7 will be described with reference to the drawings. FIG. 9 is a flowchart of a communication switching process by the frame synchronization protection method of the in-vehicle terminal device moving in a continuous communication area. The synchronization information data shown in this flowchart is
It is mounted in the control information slot of the wireless communication frame and can be detected for each frame length.

In the current communication area, during frame synchronization in the current communication area, in the forward protection processing 61, when synchronization information data is not detected continuously for the forward protection number X frames, it is determined that synchronization is lost. In the frame synchronization information data detection processing 602, synchronization information data is extracted from the received data, the frame synchronization information data is detected for each frame length, and the frame synchronization state is held. At this time, every time the frame synchronization information data is detected, the synchronization information data non-detection counter clear processing 601 clears the synchronization information data non-detection counter value.

In the synchronization information data non-detection determination processing 603, when the frame synchronization information data is not detected,
Synchronization information data non-detection counter increment processing 60
4, the non-detection counter is incremented, and further, in the synchronization information data non-detection counter value determination processing 605,
It is determined whether the number is equal to or larger than the set forward protection number X.

When it is determined in the synchronization information data non-detection counter value determination processing 605 that the number is less than the forward protection number X,
The synchronization information data detection processing is performed in the next frame while the synchronization information data non-detection counter value is held. If it is determined that the number is equal to or larger than the forward protection number X, it is determined that the communication quality of the current communication area is degraded and the state is out of synchronization. Move to

In the backward protection process 62, a backward protection number Y is set in a counter by a synchronization information data non-detection counter setting process 607. By the frame synchronization information data detection processing 608, synchronization information data is extracted from the received data. If no frame synchronization information data is detected in the synchronization information data detection determination processing 609, the process returns to the synchronization information data detection counter setting processing. When the synchronization information data is detected, the detection counter is decremented by a synchronization information data detection counter decrement processing 610, and further, it is determined in a synchronization information data detection counter value determination processing 611 whether or not the synchronization information detection counter value has become 0. Do.

In the synchronization information data detection counter value determination processing, when the synchronization information detection counter value is determined to be 0> 0, the synchronization information data detection processing is performed in the next frame while the synchronization information data detection counter value is held. Do. When it is determined that the synchronization information data detection counter value is 0, synchronization is established, and the reception of broadcast data in the next communication area is started.

As described above, in the conventional technique, as a method of switching the communication area from the current communication area to the next communication area, the frame synchronization information data is not detected continuously for an arbitrary number of frames X times, and the communication quality of the current communication area is not detected. Deterioration is determined, the frequency is switched to the next communication area frequency, and frame synchronization information data is determined as the synchronization probability of the next communication area by consecutive detection of an arbitrary number of frames Y times, and a method of shifting communication to the next communication area is used. I have.

In the prior art described above, when the frame synchronization information data has not been detected, the in-vehicle terminal device cannot reproduce the frame timing, and the received data of the frame is discarded. If the frame synchronization information data is not detected continuously for X frames, the in-vehicle terminal device determines that the frame synchronization of the wireless communication frame in the current communication area is lost, and switches to the frequency in the next communication area to perform the next communication. When rearward protection processing of the area is performed and frame synchronization information data is detected continuously for Y frames, it is determined that synchronization has been established in the next communication area, and communication is restarted.

Therefore, according to the prior art, the communication disconnection time between the roadside and the on-vehicle terminal is theoretically the sum of the forward protection and rearward protection and the frequency switching processing time, which is "(X + Y) frame time + frequency switching time". The non-detection of the synchronization information data is caused by an error in the frame synchronization information data due to the deterioration of the received electric field level. At this time, an error occurs in the broadcast data existing in the frame immediately before the detection of the frame synchronization information data. Therefore, data may be discarded. Therefore, the actual broadcast data communication disconnection time is
The time becomes longer than “(X + Y) frame time + frequency switching time”, and the broadcast data continuously supplied from the road side is lost, so that there is a problem that continuity in the broadcast communication cannot be maintained.

SUMMARY OF THE INVENTION An object of the present invention is to provide a continuous communication system which solves the problems of the prior art, shortens the communication disconnection time, and maintains the continuity of broadcast data provided from the roadside. .

[0012]

According to the present invention, in order to achieve the above object, the invention according to claim 1 is provided from a roadside centralized processing device in a continuous narrow communication area. It has a function of dividing the broadcast data into several frames and adding a division number, and a dedicated frequency switching communication slot in the communication frame for the in-vehicle terminal device to switch from the radio frequency of the original communication area to the radio frequency of the next communication area. The wireless communication frame arranged between the broadcast data and the individual data is transmitted, and the communication control slot is provided with the fractional information of the next communication area to the vehicle-mounted terminal device, and is arranged so that the communication area is not interrupted. A roadside centralized process for synchronizing frames between the plurality of roadside devices and the continuously arranged roadside devices and updating and providing broadcast data to the plurality of roadside devices at the same timing. Comprising a device to hold the following communication area radio frequency information provided from the roadside device of the current communication domain, a function of detecting frequency switching information provided from the outside,
An on-board terminal device having a function of switching from a wireless frequency in the current communication area to a wireless communication frequency in the next communication area in a dedicated frequency switching communication slot.

According to a second aspect of the present invention, in the roadside device according to the first aspect, a function of changing a communication slot for initial connection request into a frequency switching slot in the last frame of the divided broadcast data. In the in-vehicle terminal device according to claim 1, the initial connection request channel is transmitted in a frame other than the last frame of the broadcast data at the time of the initial connection request, and the last frame of the broadcast data is transmitted at the time of detecting the frequency switching information. Wherein a function of switching from the radio frequency of the current communication area to the radio communication frequency of the next communication area at the timing of the initial initial connection request communication slot is provided.

According to a third aspect of the present invention, in the in-vehicle terminal device according to the first aspect, after the frequency switching information is detected, the head of the individual communication slot allocated to the in-vehicle terminal device in the last frame of the divided broadcast data. A frequency switching notification channel is generated in the part, and the roadside apparatus is notified of the transition to the frequency switching process, and in the individual communication slot, a frequency switching notification channel of the next communication area is sent out. It is characterized by having a function that can be recognized as a channel.

According to a fourth aspect of the present invention, in the continuous narrow communication area according to the first aspect, an overlap section of a communication area with an adjacent roadside device is: maximum vehicle speed (m / sec) × frame Long (msec) x
The number of broadcast division frames + 1) [m] or more.

[0016]

Embodiments of the present invention will be described with reference to the drawings. 1 and 2 are a processing flowchart and a configuration diagram of a wireless communication frame of a first embodiment of the continuous communication system according to the present invention. 1 and 2, reference numeral 1 denotes a data receiving process, which is a processing block for receiving control slot data, broadcast data, and the like in a received frame. Reference numeral 2 denotes a frequency switching detection determination process, which is a processing block that determines whether frequency switching information has been received from base point information of a communication area provided from outside, such as a base point marker. Reference numeral 3 denotes a broadcast division final frame determination process, which extracts a division number M (M is an integer) and a division number stored in a header portion of the broadcast data divided for each frame, and outputs the divided broadcast data. Is a processing block for determining whether or not this is the last frame. Reference numeral 4 denotes a frequency switching process in a frequency switching dedicated slot, and a processing block for performing transmission of a frequency switching notification channel and switching to the next communication area in the frequency switching dedicated slot when it is determined that there is frequency switching information and the last frame is divided. It is.

FIGS. 3 and 4 are a processing flowchart and a configuration diagram of a radio communication frame according to a second embodiment of the present invention. In the first embodiment shown in FIGS. Processing 4 is performed by changing the frequency 41 in the slot for initial connection request of the last frame of the broadcast division.
It is a flowchart replaced with.

FIGS. 5 and 6 are a processing flowchart and a configuration diagram of a radio communication frame according to a third embodiment of the present invention. The frequency switching process in the frequency switching dedicated slot in the first embodiment shown in FIGS. 4 is a flowchart in which 4 is replaced with a frequency switching process 42 in an individual communication slot of a broadcast division final frame.

FIG. 7 shows an example of a configuration of road-to-vehicle communication using the continuous communication system of the present invention. FIG. 8 is an example of an operation timing chart of the first embodiment, in which the communication frame length is 25 msec. Broadcast data update cycle is 100 msec
(Broadcast data is divided into four frames).

In the configuration example shown in FIG. 8, it is assumed that the in-vehicle terminal device A travels from near the middle of the communication area 1 toward the communication area 2. While the in-vehicle terminal device A is moving in the communication area 1, the broadcast data reception process for each frame is repeated in the processing flowchart. At this time, when receiving the control slot, the next communication area frequency information stored in the control slot is obtained and held.

When the in-vehicle terminal device A reaches the base marker in the communication area 2, the in-vehicle terminal device A receives the frequency switching information from the base marker and reaches the frequency switching point from the communication area 1 to the communication area 2. Judge that you have done. This is near the control slot of the first frame of the broadcast division in the example of the timing chart shown in FIG.

Thereafter, the broadcast division final frame in the flowcharts shown in FIGS. 1 and 2 is determined at the timing shown in FIG. 5, and frequency switching is determined in the header part of the broadcast data of the broadcast division final frame. Further, in the broadcast data of the broadcast division final frame, in the frequency switching slot arranged between the data, on any of the divided channels in the frequency switching slot, the frequency switching notification to the roadside device, According to the held next communication area frequency information, in the section of the individual slot following the dedicated frequency switching slot, the wireless frequency is switched from the current communication area to the next communication area.

When the in-vehicle terminal device A generates a frequency switching notification on any of the divided channels in the frequency switching slot, the in-vehicle terminal device A generates a frequency switching channel number by generating a random number and generates another frequency switching channel number. A timing collision is avoided when the terminal device generates a frequency switching notification in the same frame. Further, the frequency switching may be completed in the entire time in which the individual slot is allocated, and this time is a sufficient time as compared with the time required for the frequency switching of the in-vehicle terminal device.

In FIG. 7, the radio communication frame provided from the roadside apparatus 2 is frame-synchronized with the roadside apparatus 1 by the roadside central processing unit, so that the onboard terminal apparatus A after shifting to the communication area 2 Since the same frame timing as that of the communication use area 1 can be obtained, there is no need to regenerate the free timing. Therefore, data can be received in the next frame in the next communication area after frequency switching.

In the case of the second embodiment shown in FIGS. 3 and 4, in the frequency switching processing 41, the slot normally allocated to the initial connection request slot is used as the frequency switching slot only for the last frame of the broadcast division. I do. At this time, if the initial connection request slot is arranged between the broadcast data in the communication frame and the individual data as in the first embodiment, the frequency switching time is the same as in the first embodiment, In addition, since the frequency switching slot can be shared with the initial connection request slot, the individual slot in the communication frame is effectively used.

Further, in the embodiment shown in FIGS.
In the frequency switching process 42, the frequency switching is performed at the timing of the broadcast division final frame of the individual slot allocated to the in-vehicle terminal device for which the frequency switching is to be performed. , 100 Byte (1 By) which is the same as the individual communication slot
te = 8 bits), the data transmission rate in the radio frame is 512 Kbps, and the information length of the frequency switching notification is 16 Bytes
When e (including the header) is set, the time allocated to the frequency switching is as follows. Frequency switching time = (1/512 KHz) × (100-1
6) × 8 = 1.125 (msec)

This value is expressed by P using a general-purpose PLL-IC.
It can be realized with an LL-type oscillator, and can be configured at low cost and easily. That is, it is sufficient to allocate only one individual communication slot as a frequency switching slot. Therefore, in the third embodiment, the frequency can be switched without any influence on the initial connection request processing of another in-vehicle terminal device, and continuous communication of broadcast data can be maintained.

The frequency switching information is notified asynchronously to the radio communication frame. The maximum number of frames required from the acquisition of the frequency switching information to the completion of the frequency switching is approximately equal to four when the number of divided frames of the broadcast data is four. 5 frames (when frequency switching information is detected at the broadcast data reception timing of the broadcast division final frame). Now, the maximum vehicle speed of the in-vehicle terminal device A is set to 180 [Km / h] (50 cm / sec).
Assuming c), when passing through the communication switching point at the maximum vehicle speed, assuming that 5 frames are required for frequency switching, the in-vehicle terminal device A proceeds 6.25 [m] from the frequency switching information acquisition timing to the completion of switching. Will be. That is, a point where communication in the communication area 1 is not normally performed from the base point marker of the communication area 2 (in other words, when the in-vehicle terminal device A receives the reception sensitivity point), the overlap section between the communication area 1 and the communication area 2 in FIG. The distance to the following points) is 6.2
It can be seen that continuous communication becomes possible by securing 5 (m) or more. Therefore, the overlap section of the communication area with the adjacent roadside device is the maximum vehicle speed (m / sec) × the frame length (msec) × (the number of broadcast divided frames + 1).
By arranging them so as to be (m) or more, more accurate continuous communication can be performed.

[0029]

According to the present invention, as described above, in the communication area switching between a plurality of roadside apparatuses constituting a continuous narrow communication area, an overlap section is provided to synchronize frames between the roadside apparatuses. Tori, or (broadcast data division number +
1) By performing frequency switching information acquisition and frequency switching processing within a frame, the broadcast data communication disconnection time at the time of communication area switching, which is a problem of the conventional method, is suppressed to a short time, and most of the circuits are controlled. In logic or software processing,
It can be easily realized, the size of the in-vehicle terminal device can be reduced, and the overlap section between adjacent communication areas is limited in consideration of the communication frame period, broadcast data update timing, and the maximum vehicle speed of the in-vehicle terminal device. By doing so, there is an effect that the layout design of the roadside device can be performed relatively easily.

[Brief description of the drawings]

FIG. 1 is a processing flowchart of a vehicle-mounted terminal device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a wireless communication frame according to the first embodiment;

FIG. 3 is a processing flowchart of a vehicle-mounted terminal device according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram of a wireless communication frame according to the first embodiment;

FIG. 5 is a processing flowchart of an in-vehicle terminal device according to a third embodiment of the present invention.

FIG. 6 is a configuration diagram of a wireless communication frame according to the embodiment.

FIG. 7 is an explanatory diagram of an operation example of road-vehicle communication according to the present invention.

FIG. 8 is a diagram showing an example of an operation timing chart according to the first embodiment of the present invention.

FIG. 9 is a diagram illustrating an example of a processing flowchart according to a frame synchronization protection method.

[Explanation of symbols]

1 Data reception processing 2 Frequency switching information detection determination processing 3 Broadcast division final frame determination processing 4 Frequency switching processing using frequency switching dedicated slot 41 Frequency switching processing using initial connection request slot 61 Forward protection processing 62 Rear protection processing 601 Synchronization information data not available Detection counter clear processing 602 Frame synchronization information data detection processing 603 Synchronization information data non-detection determination processing 604 Synchronization information data non-detection counter increment processing 605 Synchronization information data non-detection counter value determination processing 606 Frequency switching processing 607 Synchronization information data detection counter setting processing 608 frame synchronization information data detection processing 609 synchronization information data detection determination processing 610 synchronization information data detection counter decrement processing 611 synchronization information data detection counter value determination processing

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H180 AA01 BB04 CC24 5K067 AA42 BB36 CC02 CC04 CC14 DD25 DD34 EE02 EE10 EE44 EE71 GG01 GG11 HH22 JJ39

Claims (4)

[Claims] The present invention has a function of dividing broadcast data provided from a roadside central processing unit into several frames and adding a division number in a continuous narrow communication area, and a vehicle-mounted terminal apparatus is provided with a wireless communication function of a current communication area. In order to switch from the frequency to the radio frequency of the next communication area, a wireless communication frame in which a dedicated communication slot for frequency switching is arranged between the broadcast data and the individual data in the communication frame is sent out. To the on-board terminal device,
Synchronize frames between a plurality of roadside devices arranged so that communication areas are not interrupted and the continuously arranged roadside devices, update broadcast data to each of the plurality of roadside devices at the same timing, A roadside centralized processing device to provide, a function to hold the next communication area radio frequency information provided from the roadside device in the current communication area, and to detect frequency switching information provided from outside, A continuous communication system comprising an in-vehicle terminal device having a function of switching from a radio frequency in a current communication area to a radio communication frequency in a next communication area. 2. The roadside apparatus according to claim 1, further comprising a function of changing a communication slot for initial connection request to a frequency switching slot in the last frame of the divided broadcast data. The in-vehicle terminal device transmits the initial connection request channel in a frame other than the last frame of the broadcast data at the time of the initial connection request, and transmits the initial connection request communication in the last frame of the broadcast data at the time of detecting the frequency switching information. A continuous communication system having a function of switching from a radio frequency of a current communication area to a radio communication frequency of a next communication area at a slot timing. 3. The in-vehicle terminal device according to claim 1, wherein
After detecting the frequency switching information, in the final frame of the broadcast data division, generate a frequency switching notification channel at the head of the individual communication slot allocated to the in-vehicle terminal device,
A function of notifying the roadside apparatus of the shift to the frequency switching processing, and having a function of recognizing the frequency switching notification channel after transmitting the frequency switching notification channel of the next communication area in the individual communication slot. Continuous communication system. 4. In a continuous narrow communication area according to claim 1, an overlap section of a communication area with an adjacent roadside device is: maximum vehicle speed (m / sec) × frame length (msec) ×
A continuous communication system characterized by being arranged so that (the number of broadcast divided frames + 1) [m] or more.