Peer Broadcast Features

Everyone understands today that over the past thirty years, television has changed dramatically and ordinary television does not mean as much as it used to. IPTV is gaining more and more popularity due to its advantages that have been repeatedly promoted, both by us and other companies. The most striking advantage of IP television for the end user is the high quality video broadcast. High quality here is achieved through the use of technologies of various kinds, some of them are adaptive broadcasting technologies, content transmission over closed managed networks and, of course, peer-to-peer technology. We talked about adaptive broadcasting in our first articles, so now let's talk about peering.




During the first decade of the 21st century, a number of peer-to-peer systems were developed and implemented: FastTrack, eDonkey2000, BitTorrent, F2F. Each system was a step in the evolution of the peer-to-peer model. Most internet users are already familiar with the BitTorent protocol. Let me remind you that this is a peer-to-peer protocol designed for exchanging files over the Internet, where a peer is a client participating in a distribution. As you know, with the usual client-server interaction model, the client has an active role (creating communication sessions, requests, communication with the server), and a server has a passive role (responses to requests from the client). Usually these are two different programs.
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For the peer-to-peer model, it is characteristic that all final equipment has similar properties. Each node is both a client and a server. This gives the possibility of scaling and resource allocation, there are no download queues, while the files are downloaded are in small segments; the less a segment is available, the more often it will be transmitted. Thus, the presence of a “sider” in the network (the one who distributes the already downloaded file) with the full file for downloading is optional — the system distributes the segments between the “peers” so that they can later exchange the missing segments. It is important that the uploaded file segments are immediately available to other clients. Such an organization of customer interaction significantly reduces the load on the network, and with today's constant increase in video traffic, it was relevant to continue this advantageous file-sharing technology. Users do not interfere with the exchange of packets in this way, maintaining a stable channel broadcast. It formed the basis of torrent television.

With such a broadcast organization, each user (peer) is both a client and a server at the same time. When a user views video content, this content is stored on his hard disk. Another user connects to the main broadcast server to get a list of nearby clients that already have the necessary video content downloaded. If the required content is located near the user making the request, then the multimedia content is downloaded from nearby clients, if not, the required content is downloaded from the nearest broadcast server.

There is an important difference between a peer to peer broadcast and a peer to peer file sharing network — the need to deliver consistent pieces of data. Interestingly, for file-sharing networks it was an advantage, for broadcasting is a disadvantage that can be leveled by the introduction of a window of available pieces of data on each node. Increasing this window will result in an increase in data transfer delay, a decrease will entail an increase in cross-traffic with neighboring nodes.
The following schemes are used to improve the service:
- video coding with different quality profiles and distribution through different nodes of the peer-to-peer network,
- control the size of the window of available pieces on the peering nodes,
- incentive mechanisms for customers with a high return rating,
- traffic localization.

When organizing an IP television broadcasting system according to peer-to-peer technology, a “nonprofessional” may have a number of questions, for example, what should be the total maximum size of files downloaded and stored on a hard disk, because the user is not interested to give all disk space for the sake of high-quality TV viewing; Also interesting is the duration of storage of these files on the disk; and a critical mass of users for peering to work. And the answers to these questions are quite simple. Two peers are enough for a peering broadcast to work, one that acts as a server and broadcasts the necessary content to the second, the second one in turn views it. Of course, the speed of the Internet should be sufficient for normal distribution to one, and for reception from another. The impact of Internet speed loses importance when the peering participants increase, the more of them, the better the distribution. About the storage time of files - usually the storage time for files in a user archive is no more than 24 hours, that is, all information that exceeds this limit is automatically overwritten, and the earliest one is deleted. And finally, the size of the downloaded files - usually it is 1 GB, the system chooses such a size by default.



So, as a result, I would like to note that peering broadcasting today is an important component of IP television. The use of peer-to-peer technology allows you to significantly reduce the load on the broadcasting network, maintain the quality of the transmitted content, organize live broadcasts with minimal delays that are not possible, for example, with satellite TV and much more.