The Network Video Surveillance Academy The CCTV industry continues to grow. The last years most important boosting factor is the growing interest and demand for IP-based camera surveillance. The technological development is far ahead of the commercial adaptation by the security industry. The market has reacted fast and with enthusiasm. The security industry has been surprisingly slow to pick this up and of the verge of being dismissive of this technology. Lately however the security industry has realised the potential market that IP-camera surveillance offers.

Missing knowledge about the technology is part of the slow pick up rate of demand from the market. This applies not least to security installers. Against this background, SecurityWorldHotel.com - in cooperation wit the security technlogy publication Detektor International - introduces the Network Video Surveillance Academy. In four parts and six chapters, this editorial project will describe the different components and aspects of digital networked video surveillance.

Figure 1: A circuit-switched network utilizes a dedicated closed circuit.

Figure 2: A packet-switched network routes each packet independently.

Figure 3: Cable and antenna layer - the first building block.

You might ask, "What is the difference between transmission and communication?" Consider an analogy from human speech. Think about the acoustic waves in the air generated by speaking. These waves are transmitted, but they are a long way from communicating. The words that come out must be organized to make any sense. If they come out too quickly or too slowly, the speaker will not be understood. If many people speak simultaneously no one is understood. If someone speaks a language you don't understand, information is lost. Speaking generates information, but it is not necessarily communicated, or understood.

Digital communication has similar problems that need to be overcome. The receiver must know how message bits are organized to understand the message. Additionally, some rules must specify what will happen if many network devices try to use a shared media simultaneously. The best way to ensure that network devices send and receive in compatible ways is to adhere to standardized protocols that define the rules and the manner in which the devices initiate and carry on communication.

The Local Area Network Infrastructure
Local Area Networks (LANs) are used for connecting network devices over a relatively short distance. Typically, a LAN operates in a limited space, such as an office building, a school or a home. LANs are usually owned and managed by a single person or organization. They also use certain specific connectivity technologies; often some type of shared media.
An important feature of a LAN is its topology, where the term topology refers to the layout of connected network devices on a network. We can think of topology as a network's shape. Network topologies can be categorized into the following basic types:

* The bus topology uses a shared communication medium, often referred to as a common bus, to connect all network devices (Figure 4). A device that wants to communicate with another device on the network sends the packet onto the bus. All devices that are connected to the bus will receive the sent packet but the intended recipient is the only device that actually accepts and processes the packets.

Figure 4: Bus topology uses a common bus to connect network devices.

* The star topology features a logical communication center to which all network devices are directly connected. Each device requires a separate cable to the central point and consequently all packets will travel through the communication center (Figure 6).

Figure 6: Star topology uses a star-shaped network to connect network devices.

The standardized protocols utilize different network topologies together with the cable and antenna layer to build different LAN architectures that are either wired or wireless. These protocols offer the second building block for successful digital communications, the transmission layer (Figure 7).

Figure 7: Cable and antenna layer and the second building block - the Transmission layer.

Interconnecting LANs in an IP-based Architecture
So far, we have described how network devices can communicate over different types of LANs. However, different LANs are designed for different goals and needs. Hence, every so often it is necessary to interconnect several LANs to allow communication over the network boundaries. Such a geographically scattered, interconnected collection of LANs is commonly referred to as a Wide Area Network (WAN). Probably the most familiar WAN is the Internet, which spans most of the globe.

The Internet protocol suite is a layered protocol family where each layer builds upon the layer below it, adding new functionality. The lowest layer is concerned purely with sending and receiving data utilizing the transmission layer. At the top are protocols designed for specific tasks, such as sending and receiving motion pictures, sound and control information. The protocols in between handle things such as dividing the message data into packets and forwarding them reliably between network devices.

The Internet Protocol (IP) is the basis of the Internet protocol suite and is the single most popular network protocol in the world. IP enables data to be transmitted across and between local area networks, hence the name: Inter-net Protocol. Data travels over an IP-based network in the form of IP packets (data units). Each IP packet includes both a header and the message data itself, where the header specifies the source, the destination, and other information about the data. IP is a connectionless protocol where each packet is treated as a separate entity, like a postal service. Any mechanisms for ensuring that sent data arrives in a correct and intact manner are provided by higher-layer protocols in the suite. Each network device has at least one IP address that uniquely identifies it from all other devices on the network. In this manner, intermediate nodes can correctly guide a sent packet from the source to the destination.

The Transport Control Protocol (TCP) is the most common protocol for assuring that an IP packet arrives in a correct and intact manner. TCP provides reliable transmission of data for upper layer applications and services in an IP environment. TCP offers reliability in the form of a connection-oriented, end-to-end packet delivery through an interconnected network.

Figure 8: Cable and antenna layer, transmission layer and the third building block - The IP layer.

To summarize, the Internet Protocol suite provides an adaptation to the transmission layer protocols and offers a standardized architecture for communication over an interconnected collection of LANs, i.e. a WAN. This is a tremendous advance, mainly because weÕre able to connect and communicate over different physical connections in a standardized way. With IP as the basis, the Internet Protocol suite provides the third building block for successful digital communications, the IP layer (Figure 8).

Benefit from the IP-based Architecture
The Internet Protocol suite brings together all transmission layer protocols into a single, standardized protocol architecture, which can be utilized by applications for different communication purposes. As a direct result, any application that supports TCP/IP will also be able to communicate over any IP-based network.

It should be easy to see that this standardized architecture has revolutionized network communication. An ever-increasing number of applications that transfer text, sound, live pictures and more utilize IP-based architecture. All these applications and application protocols constitute the application layer and provide the fourth, and final, building block for successful digital communications (Figure 9).
Examples of applications are such as fire alarms, access controls and image/sound from CCTV.

Figure 9: The last building block - the Application layer.

Convergence
Modern digital technology allows for convergence where different services, and combinations of these services, can be provided through infrastructures that formerly accommodated only one type of service. There are three major factors that create the conditions for convergence: digital technology, transmission technology and standardized communication protocols. Digital technology allows all information - text, sound and motion pictures, for example - to be represented as bits and transmitted as sequences of ones and zeros. Transmission technology enables better utilization of available capacity in different infrastructures. Consequently, services that require high
capacity can be provided by infrastructures previously able to deliver only simpler services.

Case Study
So far we have discussed the structure of the IP-based architecture, especially in comparison with traditional circuit-switched networks. However, the preceding sections have not contained any real applications that take advantage of this architecture in the security and surveillance industry. IP-based architecture creates great opportunities for new application domains. Hence, applications that previously could not be realized can now be successfully implemented. Additionally, application domains built upon older technologies derive increased functionality when utilizing IP-based technology. For illustration, consider an application domain that has clearly taken advantage of IP-based architecture: visual surveillance systems.

In today's society, the demand for visual surveillance systems has been steadily increasing. Different camera solutions are used for monitoring activities in a variety of environments, such as shops, enterprise buildings and prisons. Up until recently, Closed Circuit Television systems (CCTV systems) were the only alternative for such monitoring. These dedicated systems typically require their own communication link between the camera and the monitor. This separate link is expensive to buy, install and maintain. Camera images are transmitted over the dedicated cabling network to time-lapse video recorders or dedicated monitors at a control center. A modern IP-based visual surveillance system on the other hand is not limited in the same way as a traditional CCTV system. Enterprises can install network cameras, IP-based visual surveillance cameras, fire alarms or access control that plug directly into the enterprise network. Such products have their own IP address, much like any network device. The main differences between these systems and CCTV systems are that video digitization is performed at the camera level and the Internet Protocol suite is utilized for transferring the pictures onto the network. This is beneficial since IP-based networks are generally available in most buildings, and because TCP/IP can be utilized with almost any existing network, there is probably no need for extra cabling. A network security system, in comparison with a CCTV system or other old type of alarm system, also saves money by reducing the amount of dedicated equipment needed to manage the security system. For example, no dedicated monitors are required.

An IP-based solution also allows images and alarms to be remotely stored and monitored over any interconnected network, such as an Intranet or the Internet. This alone creates huge advantages for enterprises that wish to outsource the monitoring of their offices and facilities to a third party surveillance and monitoring center. This center simply needs a password and the IP-address to access live pictures, via the Internet, from a site placed anywhere in the world. Moreover, the IP-based architecture creates a new world in which different applications can be completely integrated. For instance, motion pictures can be distributed to other network solutions, such as factory control management systems and access control systems.

Conclusion
The Internet Protocol suite has rapidly grown into a widespread, fundamental building block for information exchange. As communication technology becomes increasingly important, there is growing pressure to use this technology to reduce costs without sacrificing any capabilities or benefits. IP-based networks address many of the problems faced in this complex environment, while providing an elegant solution that meets present needs, as well as those to come. Ultimately, all forms of communications, including data, alarms, voice, motion pictures and entertainment, will converge into a common transporting network.

The primary benefits of an IP-based network strategy are the cost savings and operational improvements from using one converged network instead of several smaller networks dedicated to specific purposes, like data, alarms, voice and motion pictures. The second most important group of benefits from network convergence is in enabling new applications. New applications not only drive cost reductions; they can also be a source of new revenue as they provide value essential to enterprises and users.

Convergence is here and the benefits are real. Now it's time to pick strategic partners - those who understand the broad scope of needs and are committed to meeting them - and take the first step towards an IP-based future.