Design and Implementation of IPTV System Platform Based on CDN and P2P Technology


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I. Introduction

With the popularity of Internet broadband in China, people have put forward a variety of application requirements for the Internet. The various forms that exist today, such as online games, online movies and e-mails, have greatly enriched people's lives. With the combination of digital multimedia technology and computer network technology and home appliances, IPTV that integrates multimedia content and broadband network platform will become the next promising and new broadband service model in the world.

Second, the basic concept of IPTV

IPTV (Internet Protocol TV or Interactive Personal TV) means Internet Protocol Television, also known as Interactive Internet TV, is an Internet-based multimedia communication technology. IPTV utilizes the infrastructure of broadband networks, using home televisions or computers as the primary terminal equipment, transmitting television signals over the Internet Protocol (IP), and providing home users with a variety of interactive digital media services, including television programming.

The working principle of IPTV is to encode and process the TV signal data at the source end into a data format suitable for IP network transmission, and then transmit it through the IP network, and finally decode it at the receiving end, and then play it through a computer or a television. Due to the high data transmission speed requirements, the latest high-efficiency video compression technologies, such as H.264, MPEG4, etc., are used. Its main features are interactivity and real-time.

Third, CDN technology

The full name of the CDN in English is ContentDeliveryNetwork, which is a content distribution network, also known as a content delivery network. This concept was proposed by a team at the Massachusetts Institute of Technology in 1996 and began research on CDN technology. In 1999, they established a professional CDN service company to provide professional services for Yahoo. Nowadays, many enterprises and service providers have begun to use the content delivery network CDN technology to improve the quality of network services to meet the needs of users.

The CDN is a value-added network built on the existing IP network infrastructure and is a layered network architecture deployed at the application layer. At the core of the CDN is the use of intelligent policy technology to push the content and services of the center to the edge of the network, enabling users to access services in the most recent and best quality of service. Key technologies include caching, load balancing, content routing, Content distribution, content storage, content management, and more. The technical advantages of CDN include: (1) global load balancing, fast access, allowing users to connect to the nearest server. (2) Hot content is actively transmitted, automatically tracked, and automatically updated. (3) Seamless integration, high reliability, availability and scalability. (4) Reduce the occupation of network bandwidth resources and have intelligent management control capabilities. (5) The content sent is protected, and the content provider can decide the content of the service locally.

Based on the above advantages, CDN technology can improve the utilization of broadband resources and increase the popularity of streaming media on the Internet. These applications include online play, music on demand, live TV, interactive games, etc., which greatly promote the development of Internet applications and services.

However, existing CDN networks are only built for the traditional Internet network structure, content delivery and service development methods. If they are directly used to provide services for IPTV services, there are still some shortcomings. For example, the video encoding format is insufficiently supported, the delay is too large, the broadcast-level video service cannot be provided, the system structure is too simple, and as the service capability expands, continuous investment is required. In order to be able to undertake the storage, distribution and transmission of IPTV services, it is necessary to optimize and transform the existing CDN technology.

Fourth, P2P technology

P2P is an abbreviation for peer-to-peer connection peertopeer mode. At present, there is no standard definition of P2P in the industry. Simply put, P2P technology is a technology used to exchange data or services directly between different PC users without relay devices. It breaks the traditional Client/Server model. In a peer-to-peer network, each node has the same status, with both client and server features, and can serve as both a service consumer and a service provider.

P2P adopts a completely different content delivery method than CDN. The core of P2P is to use user resources to transfer files in a peer-to-peer manner, which is completely different from the traditional client server computing model. P2P achieves a fast exchange of files without relying on servers through a "decentralized" design and multipoint transport mechanism. The P2P-based IPTV architecture can reduce the threshold for broadcasting and broadcasting of IPTV services, allowing more users to participate and provide self-made multimedia content for global coverage-based sharing and distribution, while also saving between telecom operators. Docking traffic and reducing network construction costs.

However, P2P systems also have obvious shortcomings, that is, usability problems. Although P2P is reliable from the whole system, P2P is unstable for a single content or a single task, and each Peer can terminate the service at any time. Even if you quit the system, the exchanged content may be deleted or terminated at any time.

So far, P2P networks have experienced several eras such as centralized directory P2P network model, pure P2P network model, hybrid P2P network model and structured network model. Each model has its own advantages and disadvantages, and some still have their own difficulties. Overcoming the shortcomings, therefore, in the current stage of P2P technology application, various network structures can still coexist, and even present forms of mutual learning.

V. Fusion of CDN and P2P technologies

CDN and P2P are used in different fields, CDN is mainly used for reliable web and streaming content distribution, and P2P is mainly used for content exchange. Both technologies have advantages and disadvantages.

Obviously, the advantages and disadvantages of CDN and P2P technologies have certain complementarities in application. If combined with the scalability of P2P and the reliability and manageability of CDN, it is possible to build a manageable IPTV system platform capable of carrying carrier-grade content applications.

From the perspective of convergence, there are two forms of CDN and P2P integration. One is to organize the CDN Cache device in P2P mode, and use P2P directory service and multi-point transmission capability to realize content exchange between CDNCache devices and improve The content distribution capability of the CDN; the other is to introduce the management mechanism and service capability of the CDN into the P2P network to form a CDN-based content core with P2P as the service edge architecture. Without this, the CDN cost can be increased without increasing the CDN. At the same time, the CDN service capability is effectively improved, and the disadvantages of the P2P application are more effectively avoided. Under this architecture, the user needs to obtain the service through the P2P client.

In comparison, the first approach does little to improve the scalability of the system, only to improve the content distribution capabilities of the CDN from the management and control plane. The second method has a wider application prospect and is the most ideal media service bearer platform solution under the current carrier network conditions.

Our CDN and P2P integration optimization solution is based on the CDN. It retains the architecture and functions of the original CDN system at the backbone level, and introduces P2P technology at the edge nodes to share files and streams. The combination of CDN technology and P2P transmission.

Sixth, IPTV system architecture

The IPTV system platform designed in this paper adopts distributed architecture deployment, and provides an end-to-end solution based on the above-mentioned CDN and P2P integration technologies.

Due to the loose coupling and high scalability of streaming media, a typical IPTV system architecture adopts a layered mode in terms of the vertical control function of the IPTV architecture, so that application development on the platform system can be based on changing business applications. The service and function components of the specific IPTV system platform include a Web portal service layer, a service service layer, a system support layer, a streaming media transport layer, a bearer network layer, and a terminal layer.

(1) Web portal business layer

Provide a variety of applications and services to users in the form of WEB websites. For example, video on demand, live video, video conferencing, distance education, visual chat, etc. With WEB mode, the client can implement video on demand and other video interactive activities by using a browser. No need to install any other software, no need to make any settings, and the client is maintenance-free.

(2) Business service layer

The business service layer assumes all the basic functions of IPTV service operation, including channel management, media asset management, streaming media coding, content storage management, and content review.

(3) System support layer

The system support layer is an integrated management and operation support system for IPTV service operations, including multiple subsystems such as user management, authentication and billing, digital copyright protection (DRM), system real-time monitoring, and network configuration management.

(4) Streaming media transport layer

The optimization technology of CDN and P2P is used to distribute and transmit streaming media, which avoids traffic hedging on the backbone network. Through this centralized distributed architecture (see Figure 1), P2P traffic is strictly limited to the same edge node.

(5) Bearer network layer

IPTV is a real-time streaming media service with high requirements for end-to-end bandwidth, delay, jitter and bit error rate. The bearer network layer uses the IP network as the video bearer network to support the broadcast type transmission technology, and the core network and the metropolitan area network support the IP multicast technology.

(6) Terminal layer

There are two ways to watch video programs through the IPTV system platform: one is to watch through a PC, which is a widely used form; the second method is to use a TV to connect to an STB (Digital TV Set Top Box) for viewing. This form is more representative of the charm of IPTV.

Seven, the advantages of the system platform

(1) Peer-to-peer information circulation between users: It can realize user interaction, completely liberate from the traditional control of centralized streaming media, reduce the threshold of technical application, and realize interactive live broadcast and interactive on-demand that are difficult to achieve by traditional streaming media operation platform. ;

(2) Powerful audio and video file operation functions: support file operations for audio and video programs, such as preview, modify, cut, merge, delete, etc.

(3) Digital copyright protection (DRM) management function: copyright protection for digital programs can be realized. Even if illegal users download content to the local, they cannot play normally, effectively protecting the intellectual property rights of content providers;

(4) Perfect user authentication management: perfect user management and authentication mechanism to achieve multi-level user management;

(5) Load balancing management to effectively ensure operational efficiency: The system provides perfect load balancing function, real dynamic task allocation based on server CPU, memory monitoring and real-time monitoring of web tasks, and accurately balances user-on-demand requests into cluster servers. Streaming the server side, so that the load can be truly balanced, so that each server in the server cluster can maximize efficiency, improve overall network performance, improve self-healing, and ensure critical applications of the network video on demand platform;

(6) Good capacity expansion: a distributed structure system is adopted to facilitate the addition of a video server, and the simple setting of the background management system can realize the expansion of the video domain cluster group and easily meet the system expansion requirements;

(7) Powerful billing management function: The system provides multiple ways for user authentication and billing. It can define charging standards according to user types, and flexibly customize multiple billing types, preferential policies, and package combinations.

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