WO2010099658A1

WO2010099658A1 - Mobile communication system and vehicle monitoring system using wireless local area network

Info

Publication number: WO2010099658A1
Application number: PCT/CN2009/070641
Authority: WO
Inventors: 闫建华
Original assignee: 深圳市华利通科技有限公司
Priority date: 2009-03-05
Filing date: 2009-03-05
Publication date: 2010-09-10

Abstract

A mobile communication system and a vehicle monitoring system using a wireless local area network are provided in the present invention. The system includes: a wireless access point mounted on a vehicle, multiple terminal equipments which are disposed by scheduled distance along the vehicle running path and have fixed location, and a central monitoring host computer which is connected with the multiple terminal equipments through a switch; the wireless access point is connected with at least one video collection and processing equipment, and the wireless access point selects an available terminal equipment to set up communication connection based on the link layer signal intensity indication during moving; the central monitoring host computer takes the detected available terminal equipment as the default gateway to maintain the communication connection with the video collection and processing equipment. The system runs steadily, the seamless roam in a wireless local area network can be accomplished, the continuous and expedite communication link is insured, and the drop of data will not happen in the present invention.

Description

Description Mobile communication system and vehicle monitoring system using wireless local area network

The present invention relates to mobile communications, and more particularly to a mobile communication system and a vehicle monitoring system using a wireless local area network. Background technique

The 802.l lb/g/n protocol is used in wireless LANs, including wireless access points (APs) and multiple terminal devices (SAs). A common application is that multiple mobile terminal devices SA access an AP, and the AP is generally fixedly installed, as shown in FIG. When there are multiple APs in the system, even if the current AP signal becomes weak, or the SA enters the area covered by another AP due to the movement, the SA does not automatically switch to the AP with strong signal in the area. The road is interrupted, which affects the normal use of the service. The schematic diagram is shown in Figure 2.

This traditional networking method cannot meet the communication requirements between the host computer and the terminal device in mobile communication in some special occasions. For example, in road/railway mobile surveillance, because if multiple APs are used, when an SA (such as a notebook's own wireless network card) moves out of the signal range of an AP, it will not quickly switch to another AP. Large, packet loss occurs during communication. Summary of the invention

The technical problem to be solved by the present invention is to provide a link interruption and a large delay when a terminal device switches from one wireless access point to another in the above-mentioned wireless local area network communication system in the prior art, and provides a defect. A mobile communication system using a wireless local area network, which enables seamless roaming in a wireless local area network.

The present invention also provides a vehicle monitoring system using a wireless local area network.

The technical solution adopted by the present invention to solve the technical problem thereof is: constructing a mobile communication system using a wireless local area network, comprising a wireless access point and a plurality of terminal devices, wherein the wireless access point is a mobile wireless access point, where the plurality of terminal devices are fixed in position and deployed at a predetermined interval, and the wireless access point selects terminals available in the plurality of terminal devices based on the strength of the link layer signal during the moving process. The device establishes a communication connection.

In the mobile communication system using a wireless local area network according to the present invention, the wireless local area network complies with the IEEE 802.11 protocol.

In the mobile communication system using the wireless local area network according to the present invention, the predetermined separation distance is such that signal coverage ranges of two adjacent terminal devices at least partially overlap.

The technical solution adopted by the present invention to solve the technical problem thereof is: constructing a vehicle monitoring system using a wireless local area network, comprising a wireless access point installed in the vehicle, and a fixed position at a predetermined interval along the traveling route of the vehicle. a plurality of terminal devices, and a central monitoring host connected to the plurality of terminal devices through a switch; the wireless access point is connected to at least one video collection and processing device, and the wireless access point is based on a link during the mobile process The layer signal strength indicates that the available terminal device is selected to establish a communication connection; the central monitoring host maintains a communication connection with the video collection and processing device with the monitored available terminal device as a default gateway.

In the vehicle monitoring system using the wireless local area network according to the present invention, the wireless local area network complies with the IEEE 802.11 protocol.

In the vehicle monitoring system using the wireless local area network according to the present invention, the predetermined separation distance causes signal coverage of adjacent two terminal devices to at least partially overlap.

In the vehicle monitoring system using the wireless local area network according to the present invention, the central monitoring host is a computer equipped with video decoding software and/or hardware, and the video collecting and processing device includes a network video card and at least one connected thereto camera.

The mobile communication system using the wireless local area network embodying the present invention has the following beneficial effects: The system operates stably, can realize seamless roaming in the wireless local area network, ensures continuous communication of the communication link, and does not cause data packet loss. DRAWINGS

The present invention will be further described below in conjunction with the accompanying drawings and embodiments, in which:

1 is a schematic diagram of the architecture of a conventional communication system using a wireless local area network; 2 is a schematic diagram of a conventional communication system using a wireless local area network to switch APs during operation; and FIG. 3 is a schematic diagram of the architecture of a communication system using a wireless local area network according to the present invention. detailed description

The concept of the present invention is to design a wireless access point (AP) as a mobile AP and fix the location of the terminal device on the infrastructure of the wireless local area network, and implement wireless mobile roaming by means of gateway intelligent switching to implement wireless local area network. Seamless roaming in. After testing with the Datal inc 810E+ product, the system constructed by the technical solution of the present invention is stable in operation, can realize seamless roaming in the wireless local area network, and ensures continuous and smooth communication link without data packet loss.

3 is a block diagram showing the architecture of a communication system using a wireless local area network according to the present invention. The common application is that the SA accesses the AP, and the solution of the present invention adopts the method of SA fixed and AP mobile roaming. As shown in FIG. 3, SA1, SA2, and SA3 are installed at a predetermined interval, so that the wireless signal coverages of the adjacent two terminal devices intersect (ie, at least partially overlap), and the area enclosed by the dotted line in the figure is the wireless of each terminal device. Signal range, a system consisting of three terminal devices has two signal overlap areas. The terminal devices SA1, SA2, SA3, and PC2 are connected to the switch.

Because the 802. l lb/g protocol specifies that multiple APs can be connected to the same AP, the available signals between the AP and the SA are shown in Table 1.

According to Table 1, it can be known that no matter where the AP goes, always connect at least one SA. In the coincidence area, only the gateway of the designated computer is the address of the corresponding SA, and there is no switching time in the whole process. Seamless switching is possible.

In one embodiment, a Datal inc 810E+ wireless device is used as an AP to connect to a computer PC1; another three 810E+ wireless devices are used as an SA to connect to a computer PC2 to access the switch, and two computers PC1 and PC2 Use the network ping command with each other. There is no packet loss under the default parameters, and the system works stably.

The technical solution of the present invention can be mainly used for road and railway mobile monitoring, because if multiple APs are used, when an SA (such as a notebook's own wireless network card) moves out of the signal range of an AP, it will not quickly switch to another AP. The delay is large, but an AP can communicate with multiple SAs. When an AP spans several SA signals, there is no handover in the wireless part.

In the foregoing embodiment, two computers are used. After the computer modifies the gateway by polling, the return value of the ping command is accumulated to a certain number of times, and the state of the AP is judged. If true, the other computer is notified to be modified to the specified one. Gateway, the two computers use the industrial 0PC data interface communication, after testing, the computer PC2 scans the computer PC1 data for a minimum of 20ms, can be modified within 50ms using the APi function. In the actual application of vehicle monitoring, with video decoding software and/or hardware, real-time images can be viewed on the computer PC2. Due to the buffer in the video server, the loss of several video frames will not cause the image quality to drop.

In this embodiment, the system includes three terminal devices SA1, SA2, SA3, an AP, and two computers PC1 and PC2, and the gateway is modified as follows:

PC1 modifies the gateway to SA1, and pings the AP to get the return value a;

The PCI modification gateway is SA2, and the ping AP gets the return value b;

The PCI modification gateway is SA3, and the ping AP gets the return value c;

If the value of a is valid, it indicates that the mobile AP is within the signal range of SA1, and notifies PC1 to modify the gateway to the address of SA1;

If the values of a and b are valid, the AP informs PC1 to modify the gateway to the address of SA2 within the signal range of SA1 and SA2.

If the values of b and c are valid, the AP informs PC1 to modify the gateway to the address of SA3 within the signal range of SA2 and SA3. If there are multiple SAs, and so on, the number of valid values obtained under normal conditions is less than or equal to 2. If a SA fails, because the above mentioned procedure is polling, when the mobile AP goes out of the signal range of the faulty SA, it will automatically recover and will not crash.

In the embodiment of the present invention, the two machines use the 0PC interface to transfer data to each other. The programming environment is VB (Visual BASIC). With the API function provided by Microsoft, the gateway is modified immediately and does not need to be restarted.

The technical solution of the present invention is used in a vehicle monitoring system for roads and railways. In one embodiment, the SA is generally fixedly installed along the road and the railway. It can be shot in two directions with a 17db directional antenna plus a 2cm. The straight line is placed at a SA every 2km, and the turning place is 500~1500m. An SA can guarantee signal coverage. Calculated at a speed of 100 km/h, 28 m/s, in the embodiment using the Datalinc 810E+ product as SA, the signal coverage is at least 2 km, which is very effective.

The technical solution of the invention is mainly applied to the emergency monitoring in the railway compartment, and the distance between the train and the train usually exceeds the signal range of one SA, and the existing telephone network MODEM of the highway railway is used to dial the centralized control center, and the new one is currently The high-speed, railway has an optical fiber interface that can be used directly. Therefore, there can be multiple APs along the same line, for example, one AP is installed in each vehicle. These APs may have the same Service Set Identifier (SSID) or have different SSIDs. In the latter case, the AP SSIDs in a group of terminal devices, such as SA1, SA2, and SA3, need to be modified accordingly. If you need to monitor both directions, deploy 2 sets of terminal equipment.

When the mobile communication system using the wireless local area network of the present invention is applied to the in-vehicle emergency monitoring, the computer PC1 and the wireless AP can be installed in the passenger compartment. As a video capture and processing device, a computer video card responsible for video encoding is installed in the computer PC1, and real-time video images in the car are collected by at least one camera, and the video signals are transmitted to the computer PC2 ₀ through the wireless AP, the terminal device and the switch. PC2 can be used as a central monitoring host, which is equipped with video decoding software to decode the received video signal, and display the real-time video image in the car and store the image data on the display device connected to the central monitoring host. The central monitoring host is in the storage device.

The wireless equipment used in this scheme has a low price. For example, if the domestic product is used, the cost of an SA station after considering the antenna-feeder system is only a thousand yuan.

Claims

Rights request

A mobile communication system using a wireless local area network, comprising a wireless access point and a plurality of terminal devices, wherein the wireless access point is a mobile wireless access point, and the plurality of terminal devices are fixed in position And deploying at a predetermined interval, the wireless access point selects a terminal device available in the plurality of terminal devices to establish a communication connection based on the strength of the link layer signal during the moving process.

2. A mobile communication system using a wireless local area network according to claim 1, wherein said wireless local area network conforms to an IEEE 802.11 protocol.

A mobile communication system using a wireless local area network according to claim 1, wherein said predetermined separation distance causes signal coverage of adjacent two of said terminal devices to at least partially overlap.

4. A vehicle monitoring system using a wireless local area network, comprising: a wireless access point installed in a vehicle, a plurality of terminal devices fixed at a predetermined distance along a vehicle travel route, and a switch through a switch a central monitoring host connected to the plurality of terminal devices; the wireless access point is connected to at least one video collection and processing device, and the wireless access point selects available based on a link layer signal strength indication during the mobile process The terminal device establishes a communication connection; the central monitoring host maintains a communication connection with the video collection and processing device with the monitored available terminal device as a default gateway.

5. A vehicle monitoring system using a wireless local area network according to claim 4, wherein said wireless local area network conforms to the IEEE 802.11 protocol.

6. The vehicle monitoring system using a wireless local area network according to claim 4, wherein the predetermined separation distance causes signal coverage ranges of adjacent two terminal devices to at least partially overlap.

The vehicle monitoring system using a wireless local area network according to any one of claims 4 to 6, wherein the central monitoring host is a computer equipped with video decoding software and/or hardware, the video capturing and The processing device includes a network video card and at least one camera connected thereto.