Network integration of video surveillance services based on Ngn/ims (SIP Protocol) communication Platform

I. Overview

Review the video surveillance market, the monitoring platform system used by the signaling control protocol is not unified, resulting in the interconnection of the technical threshold. This is a bit similar to the 80 's China's switch market eight system of the situation. These reasons hinder the network era of large-scale carrier-level video surveillance, remote access, centralized management needs. The industry has explored two ways to solve the problem:

From the monitoring industry, in the existing platform to integrate SIP as a business communication protocol to host/manage the front-end;

From the IMS/NGN communication platform, the IMS/NGN platform is naturally suitable for the IP video surveillance system large-scale networking, distributed deployment, intelligent monitoring requirements, video surveillance system is a more powerful solution. Rib SIP is simple and flexible in the existing resources of the integrated SIP cam, equivalent to the SIP cam as a SIP terminal, add monitoring services in the background;

Overall, SIP is simple and flexible, distributed control, so sip as the future market video surveillance mainstream agreement has become the industry consensus. China Telecom Group also recommended the SIP protocol as the preferred control protocol in its "China Telecom family Video surveillance business Technical Specification". This set of SIP intelligent video Surveillance system based on broadband network, is a remote monitoring, transmission and management in one of the intelligent video Surveillance system, applicable to GA, transportation, finance, schools, hospitals, property and other fields. The system abandons the former line design concept, uses the common SIP protocol, fully satisfies the need of the network era to the large-scale carrier-level video surveillance, remote access and centralized management, and is the application solution to truly meet the telecom-class interconnection and interoperability.

second, SIP introduction

Session Initiation Protocol SIP (Sessions initiation Protocol) is an application-layer control protocol for multimedia communication over an IP network, which is used to create, modify, and terminate one or more participants ' session processes. A session may be any type of communication between endpoints, which can be video session, instant messaging, and collaboration sessions. In no event will the agreement define or limit the use of the business. Furthermore, issues such as transport, QoS, billing, and security are handled by basic core networks and other protocols.

2.1 SIP signaling control mode and distributed architecture

SIP protocol Communication mode is a distributed, client/server (CLIENT/SERVER,C/S), horizontal control structure, the use of multi-point control Unit (MCU) or full interconnect in lieu of group advertising multi-party calls, transparently support name Mapping and redirection services, divided into call signaling, Modules such as registered signaling and redirect signaling provide other relevant or independent functions and services through other relevant or independent protocol systems. It adopts the message mechanism of C/s structure, and the control of call is encapsulated into the header domain of the message and implemented by the message transmission. Therefore, the SIP system terminal is more intelligent, not only provide data, but also provide call control information, and other various servers used to locate, forward or receive messages. In this way, sip pushes the complexity of network devices to the network terminal equipment, so it is more suitable for building intelligent user terminals. SIP is a hierarchical protocol whose behavior is described by a set of equal and independent processing stages, with only loose coupling between each phase. The protocol layering description is to express thereby allowing the description of a function to span several elements in one part, an element containing a layer that refers to the set of rules that it obeys for that layer definition.

SIP Communication steps:

1) registration, initiating and locating users;

2) Media consultation, usually using the SDP mode to carry media parameters;

3) by the called Party to decide whether to accept the call;

4) Call media stream to establish and interact;

5) Call change or processing such as call transfer;

6) Call termination.

A SIP basic network architecture, which should include several basic logical units UA, Proxy server (SIP proxy), registration Server (registrar), redirect Server (Redirect server), and B2bua:

As shown in the figure above, the SIP UA or terminal forms the endpoint of the conversation: it sends or receives SIP requests and responses. The UA can be logically divided into:
UA Client: The calling party application initiating the request;
UA Server: Receives, redirects, or rejects a request, sending a response on behalf of the user to the incoming request.
SIP intermediate Servers are logical entities that SIP messages pass before they reach their final destination, which are used for routing and redirecting requests. Servers include proxy servers, redirected servers (Redirect server), registration Servers (registrar), and B2bua.

SIP, as a signaling control protocol based on the Internet environment, breaks through H. 323 the traditional design idea of centralized and hierarchical control, the core idea is to invite new members to join an existing session or create a new session, each member can interact through multicast, unicast or the combination of the two, which has many good features such as extensibility, flexibility, interoperability, reusability, etc. Therefore, SIP signaling is inherently suitable for the large-scale networking, distributed deployment and intelligent monitoring of IP video surveillance system, which is the inexorable trend of signaling mechanism development in video surveillance system.

Third, SIP network video Surveillance System

Through our understanding, the IMS/NGN system adopts the mechanism of signaling control and media stream Exchange separation, the audio and video stream in communication system is not centrally managed by SIP server, and distributed to media server through the processing and exchange of network, which avoids the bottleneck of processing the performance pressure of media stream. This enables unrestricted expansion of the monitoring scale.

SIP-based network video surveillance system adopts the domain management method to support large-scale video surveillance service. SIP Video Surveillance System consists of the following parts.
(1) Monitoring front-end
Mainly for network cameras and network video servers.
The monitoring front-end can digitize the monitoring image and send it to the client for viewing by the user.

(2) Client
Mainly for SIP video phone. The client is the video encoding data transmitted from the front end of the video monitoring, decoding the encoded data display.

(3) IMS/NGN system
The system is the core of the entire monitoring system, all the control and management have this part of the completion.

As shown in the figure above, the monitoring front end is registered and unregistered using the Register method. According to the classification of security level, it is divided into standard authentication registration, two-way authentication based on password and two-way authentication registration based on digital certificate. SIP-based call mechanism is adopted, and some custom message formats are encapsulated in the SIP message body in text form, thus forming a unified control message format and facilitating further expansion. One of the important functions of SIP protocol is to create multimedia session, and to set up the interactive method of the ability set in the related bearer protocol, through the invite method, the real-time video stream monitoring of large-scale centralized monitoring platform can be completed well. The user can view the monitoring area at any time by remote SIP video Phone and realize bidirectional voice through SIP. Control flow can also be implemented with some basic methods of sip, such as using invite or subscribe,notify mechanism to achieve alarm sending, with info or message method to achieve PTZ control and configuration. In the video surveillance business, the remote real-time control and alarm of PTZ and lens are very important functions, because the SIP protocol does not define the monitoring function, so the standard SIP protocol can not complete the monitoring of the cloud mirror control and alarm function, which needs to extend the SIP protocol. The extension of SIP should be carried out in the framework of the extended principles of the SIP protocol.

Iv. Advantages of the system

3.1 Remote monitoring requires dial-up

Network cameras and web video servers are the leading integrated SIP network video products, requiring only a simple dial-up to remotely view the monitor area from the SIP video phone and enable two-way voice calls to the scene. And if alarm output is set to the SIP video phone, once the alarm event occurs in the monitoring area, you can watch the scene from the far end immediately. It achieves the perfect combination of video surveillance and communication. 3.2 Flexible Remote control

Remote users can dial into the Grandstream SIP video surveillance terminal, through the SIP video phone digital keys or soft phones to remote viewing angle, for rotation, tilt and zoom operation. Enable users to watch freely and check where they want to see while enjoying the fun of video surveillance and convenient and flexible remote monitoring. More than 3.3 security enhancements

Grandstream's SIP video surveillance terminal can be connected to multiple external safety devices, including vibration sensors, smoke sensors, buzzers or hazard lights to create an intelligent security system with ease and flexibility. The Grandstream SIP video surveillance terminal can control the security mechanism through the scheduling policy to ensure the security of the monitoring area. 3.4 Bandwidth Savings

The SIP video surveillance terminal of Shenzhen Trend Network (Grandstream) Technology Co., Ltd. is based on the international Advanced H. e algorithm, which can easily achieve low network bandwidth transmission of high-definition images. Multiple bitstream settings are available to enable limited Internet connection bandwidth with the appropriate video quality. To get a comfortable user experience.

v. Summary

As one of the communication systems, the

        monitoring system uses the corresponding signaling mechanism to work together all the devices in the system, so that the system runs normally. Signaling system is the nervous system of communication network, which is an essential part of communication network. Signaling is a mechanism through which the user terminal of a communication network is formed, and each business node can exchange its own state information and propose the successive requirements of other devices, thus making the network run as a whole. The development trend of monitoring system is large-scale networking, distributed deployment, intelligent monitoring. The characteristics of SIP as the corresponding signaling mechanism are shown in the following table:   SIP signaling Mechanism characteristics adapt to the network environment/demand good scalability to meet the needs of large-scale networking, system upgrade and expansion; distributed architecture, upgrade and expansion only need to add the corresponding components, no need to change the original system simple To meet the maintainability requirements of large-scale networked systems; HTTP text, easy to use, easy to debug       mobile good to meet the development needs of monitoring everywhere; Support user movement, users can use PC, IP phone or traditional telephone Good new features support capabilities to meet increasing monitoring value-added business requirements, enabling fast creation of new features with existing IETF protocol integration other IETF protocols can be used to build SIP applications that can work with existing IETF protocols!.