Wireless video surveillance technology is used in many security fields. The subway safety prevention system is an important device to ensure the smooth running of the subway and whether the transportation is safe. The wireless video surveillance technology is used in the subway video surveillance system.

demand analysis

For the subway, the first thing to be monitored is the requirements for safe operation and anti-terrorism and explosion prevention. Due to the large passenger flow and complicated personnel in the subway system, and the subway is an underground space, it is closed, opaque, and unfavorable in ventilation. In the event of an accident, such as a fire or explosion, the impact will be very large, so suspicious explosives must be blocked in advance, including Some liquids, solid explosives, and toxic gases are fully prevented. In order to prevent passengers from carrying flammable and explosive items and other suspicious items that may cause major public safety accidents, the station has also strengthened security inspection measures. However, the existing security inspection equipment only performs security inspections on objects and not people, and all kinds of unsafe Hidden dangers still exist, so the monitoring of the situation in the subway car has always been the function that everyone expects to achieve, but due to the limitation of wireless transmission bandwidth and movement speed, it has not been well implemented. With the issuance of China ’s 3G licenses and 3G network Construction, real-time video surveillance in the subway car running at high speed becomes feasible. ZTE, as the leader in the domestic 3G market, has launched a "network video" video surveillance system for subway wireless solutions to meet the needs of the market. It uses networked and intelligent video surveillance technology to achieve full coverage and coverage of video surveillance in the subway. Application, here to share some experience with you.

Design of Wireless Fixed Network Converged Video Surveillance Scheme

system structure

"Network Video" video surveillance system adopts all-IP technology to provide an end-to-end integrated solution that integrates mobile and fixed networks, and can provide a monitoring front-end that meets various wireless networks such as WiFi / 2.5G / 2.75G / 3G / WiMAX , And a full range of multi-functional wired monitoring front-ends, system management platforms and portals, media distribution and storage platforms, a variety of monitoring clients (including mobile client / PC client / WEB client / hardware decoder), etc. Hardware and software equipment.

The system is based on the excellent fixed network + mobile full network design concept, in accordance with the carrier-class reliability requirements, using software modular design and advanced intelligent transcoding gateway design scheme, can provide excellent performance of mobile, fixed network fusion video surveillance Comprehensive application. For the subway system monitoring, its networking architecture is shown in Figure 1.

Front-end design

In the subway car, according to the situation of the wireless network, configure a dedicated on-board 3G wireless video server + hemisphere camera with the corresponding interface. The wireless video server itself can be configured with a hard disk to achieve local storage of high-definition, real-time video (D1 format), according to 3G Network transmission speed, set CIF real-time or D1 non-real-time (drop frame) video upload platform for monitoring center and related management personnel to call, when there is an unexpected event, you can directly call the local video recording stored in D1 format.

For the monitoring points set at each station platform and each entrance, building (escalator) ladder path, etc., you can directly use network cameras, such as network high-speed ball, network gun machine, etc., to reduce the difficulty of engineering construction, or you can use simulation Camera + video encoder way construction.

Access network design

For in-vehicle monitoring points, it is recommended to use a 3G wireless network, such as the latest 3G or 3.5G wireless network technology such as Telecom ’s CDMA EV-DO or China Mobile ’s TD-SCDMA HSPA +, to ensure that it provides sufficient upstream bandwidth and can be upgraded to LTE in the future The internet. For fixed monitoring points in the station, it is recommended to use wired connection to the network to ensure the stability and reliability of access.

Monitoring center design

The monitoring center of the subway monitoring system generally includes three types, which can be divided into three levels in terms of management. The first type is the station monitoring center, which has a large number. Each station has a local monitoring center to browse the monitoring images of the station. Have the highest authority to control the camera of this station; the second type of monitoring center is the line subway dispatch management center, generally there is one for each line, you need to know the general situation of each station and the detailed information of the train operation at any time. The video can be viewed selectively, but the control authority of the camera is one level lower than that of the station; the third category is the vehicle maintenance center, generally there are 1-2 maintenance centers on a line, and the monitoring target is mainly the station and Various types of hardware and equipment for subway trains have control authority over certain cameras, with the lowest control authority. The network architecture of the line monitoring management center and the station monitoring center is shown in Figure 2.

Mass storage design

In order to save a large amount of video recording data, it is necessary to establish a central mass storage device. According to the characteristics of video surveillance recording data recording, IP-SAN storage technology is recommended. Compared with other storage methods, IP-SAN has the following advantages:

· High cost performance;

· Strong expansion ability;

· Centralized management;

· The Ethernet technology is quite mature, reducing the complexity of configuration, maintenance, and management;

· Network-based storage system, data migration and remote mirroring are easy, as long as the network bandwidth supports, there is basically no distance limit, can better support remote disaster recovery;

Easy to integrate with existing monitoring Ethernet network;

· The network has no distance limitation and is easy to deploy.

IP-SAN combines the speed and low cost of SCSI, and the commonality and universality of IP networks and Ethernet, making IP-SAN storage solutions an economical, scalable, and well-known solution.

In the project, it is recommended to use a dual-Controller magnetic array. One main cabinet can be extended to connect three slave cabinets, providing 51 hard disk slots. Multiple IP-SAN magnetic arrays can be configured in the project to achieve large-capacity storage.

System platform design

The design of the monitoring system platform is divided into two parts: a business management platform and a media service platform. It completes the platform management functions such as device management and user account management, AAA management, business management, device configuration management, platform networking management, operation maintenance, and remote upgrade of the entire system. And video storage, distribution and forwarding functions, providing full network support for business use.

In order to ensure the safety of the system structure, the system is constructed by the management center CMS + distributed video monitoring VSS media node. The CMS equipment is placed in the subway monitoring center, which can be set as a VSS media node at each station, or nearby The cameras at the two stations are concentrated to build a VSS media node to reduce the bandwidth occupied by the video in the entire transmission network of the subway and improve the security of the system.

Intelligent application design

The multiplication of monitoring points brings more video information. Massive video information transmission means higher broadband resources, more storage space and more personnel to analyze, judge and process the video information.

At present, the traditional monitoring system is that the staff is on duty 24 hours to view the monitoring screen, make judgments based on the content of the video information, analyze and deal with abnormal behaviors, and ensure the basic safety of the community through the close combination of civil air defense and technical defense. However, it turns out that after 20 minutes of staring at the monitoring screen, the human eye's attention will seriously decline, and in the face of a large number of monitoring screens, the possibility of finding an abnormal behavior is relatively small. Based on the physiological characteristics of people, it was originally expected to increase the security level by increasing the number of electronic eyes, but now because of the rapid increase in video information, it is unable to achieve the desired goal. For the security department, video surveillance images are an important source of clues in the detection of major cases. For video records that may have clues, dozens of images are often viewed for more than ten consecutive days. The method greatly increases the difficulty of criminal investigators in obtaining evidence and the resolution cycle.

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