Need For Incentive Mechanism

Published Date: 02 Nov 2017

1. INTRODUCTION

Lots of applications, including Internet TV, online games, broadcast of sport events and distance education require support for video broadcast, for instance; simultaneously video delivery to a large number of receivers. Thus, enabling simultaneous video broadcast as a common Internet utility where any publisher can broadcast content to any set of receivers has been driving the research agenda among networking community for over two decades.

Currently, there has been huge interest in the use of peer-to-peer technologies especially for Internet video broadcast. Why it is attractive? First, it does not require support from Internet routers and network infrastructure therefore it is extremely cost-effective and easy to deploy. Secondly, a participant that tunes into a broadcast is not only downloading a video stream, but on the same also uploading it to other participants watching the program thus contributing to the overall available bandwidth. Therefore, this approach has the potential to scale with group size, as greater demand hence generates more resources. The challenge scale for video broadcast is enormous. For example, to reach 100 million viewers, 1.5Tbps aggregate capacity is needed to delivery of TV quality video encoded in MPEG-4 (1.5Mbps). Peer-to-peer technologies have appeared as important for a wide range of applications such as file download and voice over IP. However, video broadcast applications comprise different challenges than these other applications. Specifically, video broadcast imposes stringent real-time performance requirements in latency and bandwidth. Compared to original source, the arriving streams are normally a few minutes time-delayed. The video quality of the channels are usually depends on how many users are watching. The more the users the better the quality. The architecture of many P2PTV networks can be put BitTorrent as an example. For example, a user wishes to watch a certain channel, the P2PTV software contacts a tracker server to obtain addresses of peers who distribute that channel. Then contacts these peers to receive the feed. The tracker records the user's address, so it can be given to other users who wish to view the same channel. This will creates an overlay network on top of the regular internet. Peer-to-Peer streaming systems (or P2P-TV) are becoming popular among users. P2P- TV systems target the real time delivery of a video stream, thus it comprising different challenges compared to traditional P2P applications (file sharing P2P application).

IMPACTS

P2PTV takes enormous pressure to the Internet backbone and traffic access network. Among most popular P2PTV application is SOPCast, PPStream and PPLive. But the major problem is that they are closed and proprietary. After analysis of network traffic they caused then we can know the behaviour. There are 2 mode of traffic, zapping (transient state) and viewing (steady state). For impact of users and network there are 2 property. One is peer and second is traffic. Peers exited the peer list after a long period of time. A peer left only after it was disappeared from the peer list of all peers. Peer spend long time than its actual value. This leads to 3 bad effects. First, it will over-estimated number of active peers. Second, it distorted or disturbed the peer lifetime distribution. And finally, useless traffic will be generated and unnecessary overheads will be brought to the users and network.

For social impact of P2P systems in term of legal issues, copyright have undoubtedly taken the forefront since the technology has changed the societal behaviors of distributing, sharing and copying. Meanwhile, on economic aspects, main problem with P2P markets is that peers in the network can these roles (legal owner of the object, providing interaction partner, mediating service and receiving interaction partner). New mediators can release an open platform but first of all, the revenue for owners must be clear. Profit should be shared with providers and mediators if the community owner want to save distribution and delivery costs. For political aspects of P2P play an obvious role in the further development on both economical and legal levels of this technology. The possibility to share informations via P2P network give individual the information they need in order to do politics. For example, empowerment has profoundly different nature mono-directional media like TV or radio.P2P systems allow anonymous communications which make difficulties for the entity to stop spreading sensitive issues of information via identification and action upon the participants of network. Anonymous P2P system has make the sharing of information and political actions based upon sharing, less risky.

CHALLENGES

There are a lot of challenges facing by the user or inventor of some P2PTV applications. Some of them are;

Scheduling transmission of stream chunks

Originally, unstructured P2PTV tend to distribute the chunks based on a random decisions. Thus it will produce a lot of useless network traffic. This is due to duplicated chunks therefore it will delay the chunk diffusion process. This problem can be avoided by basing the chunk distribution on smarter decisions. It will reduced or completely eliminate chunk duplications and every peer can receive various chunks at the certain time. Besides, new scheduling algorithm also can be use. For example; Urgent then Latest chunk or Redistribution Capacity peer (UL/RC)

Short Start-up delay

Start-up delay is the time that passes from the selection of the channel to the time when the video starts its playback. Employment of multiple trees rather than mesh is the reason for long start-up delay. Thus mesh based trees must be used. Other than that, factors that make short start-up delay is hard to achieve is because of distribution of the tree management overhead by multiple servers and distinct scheme for channel switching.

Need for incentive mechanism

Distinct incentive scheme for cooperation integrated to the architecture.

Need for dedicated infrastructure

Introduction of the 2nd layer of the architecture, with dedicated infrastructure (DSNs)

Support for flash crowds and high chunks

Employment of redundancy of data (MDC) and network path (multiple trees)

Support for client heterogeneity

Employment of LMDC for bandwidth adaptation incentive scheme with deferred remuneration

Synchronization of client playback

Possible optimization of overlay structures

Better NAT and firewall traversal

Possible employment of the STUN protocol

Limit overhead due to signalling message

Achieve a fair resources utilization

Making peers contribute proportionally to their bandwidth

Improve system performance in reducing loss probability and chunk delivery delay with respect to mechanism with non adaptive number of contacted peers

Provide high quality of video streaming with high speed especially when it is a live streaming.

CONCLUSION

The design of P2PTV has several extra challenges compared to P2P file sharing applications. For P2PTV, a utility degree of quality for the received media must be ensured. Also it is important to satisfy the deadlines when delivering data to ensure proper playback continuity in real-time. All this requirement can be achieve if optimizing the following; start-up delay, end- to-end delay and the playback continuity. But in order to get those criteria to be optimum, best-effort environment like the Internet must be achieve too, where nodes have different bandwidth constraints.