AWERProcedia Information Technology & Computer Science 2 (2012) 318-326
2nd World Conference on Innovation and Computer Sciences - 2012
Zero-Delay Broadcasting Protocol for Video on Demand over Mobile Ad Hoc Networks Saleh Ali Alomari a *, Putra Sumari b, Samer Atawneh c a,b,c
Multimedia Computing Research Group, School of Computer Sciences Universiti Sains Malaysia, 11800 USM Pulau Pinang, Malaysia
Abstract Video on Demand (VOD) system is an electronic video rental system where the clients have the ability to request and view the video at any time, which make the VOD system become an important technology for many applications. User waiting time, wireless coverage and bandwidth allocation are major challenges of VOD services over Mobile Ad Hoc Networks (MANET’s). The importance of this paper is to find a solution to reduce the delay. Numerous periodic VOD broadcasting protocols have been proposed to support a large number of receivers. Broadcasting is an efficient transmission scheme to provide on-demand service for very popular movies. This paper proposes an enhanced method for the Staggered Broadcast (SB) protocol, known as Zero-Delay Staggered Broadcast (ZDSB) method, where the logical channel of the Local Media Forward (LMF) is partitioned into sub-channels and video segments into sub-segments as well. The results showed that the proposed system is more efficient and better than other proposed methods, where the average waiting time is less than 0.0066 in most scenarios compared to the previous available systems. Keywords: Video on Demand, MANET's, Staggred Broadcast, RSB, ERSB, MobiVoD Selection and peer review under responsibility of Prof. Dr. Dogan Ibrahim. ©2012 Academic World Education & Research Center. All rights reserved.
1. Introduction Nowadays, Video on Demand (VOD) is a multimedia service which allows a remote user to select and then view video at his/her convenience anytime anywhere he/she wants, that make the VOD become an important technology for many applications, and many significant of Periodic Broadcasting (PB) protocols have been proposed to support a large number of receivers. Broadcasting is an efficient * ADDRESS FOR CORRESPONDENCE: Saleh Ali Alomari, Universiti Sains Malaysia, 11800 Pulau Pinang, Malaysia
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Saleh Ali Alomari et all. / AWERProcedia Information Technology & Computer Science (2012) 318-326
transmission protocol to provide on demand service for very popular movies. There are many PB protocols designed to provide efficient VOD services to a potentially large number of users without using too many resources from the clients, the server or the underlying network. It is found that some existing broadcasting protocols are not practical to provide a small delay VOD service if the client buffer size is not large enough. One of the main challenges in the broadcasting protocols is how to reduce viewer’s waiting time maintaining a given bandwidth allocation, and how to reduce a client’s buffer requirement. In this paper, we proposed Zero-Delay (ZD) method that enhances the Staggered Broadcast (SB) protocol and to broadcast popular videos for mobile networks. ZDSB introduced to minimize the startup delay at client side. The rest of the paper will be organized as follows: in Section 2, the related background will be introduced and discussed on more detailed brief backgrounds. Section 3, will be an overview for previously published work, which is related to our proposed work. The proposed ZDSB method will be presented in Section 4. In Section 5, the results and conclusions will be presented. Finally, in Section 6, a conclusion of this paper will be given.
2. Related Background With the rapid development of information technology and Internet, more and more new applications emerged to challenge the way we live [1]. The advancement in wireless technology has brought a lot of benefits to private sector, public sector and for all the mobile users such as laptop user, PDA user, hand phone user and more. It helps users to transfer or share information over a distance without the use of wires and it is generally considered to be a branch of telecommunications. With the development of wireless technology, such as, IEEE 801.11 (WiFi) and IEEE 801.16 (WiMax), VOD System over MANET service has become very popular and many VOD service applications are emerging. Video on Demand concept and watching videos online is becoming very famous and very demanding and the number of viewers is keep increasing every year. There are more than 100 video search engines that can be found, such as, Yahoo Video, YouTube, Mega Video. In addition, there are more than 100 video sites are available online, such as, BrightCove, PhotoBucket, and DailyMotion, for the online users to upload, download, share, and stream videos. Statistics results from the Digital Buzz website [2] and comScorewebsite [3], shows that the average of the number of persons who watch videos online per month is estimated around 182 persons, and YouTube website serves 1 billion videos per day with around 1.2 billion streams each day worldwide. Since the number of viewers is increasing, it encourages many researches to work on Video on Demand System over MANET network, which can enable the users to join and move out from the system at any time, and the most interesting part is they can download and stream their favorite movie on their mobile devices. There are a lot of research are being conducted on for VOD System over MANET network and more and more techniques are introduced to improve the system’s application and quality *4+. 2.1. Periodic Broadcasting (PB) protocols Greatly, VOD system can be improved by using multicast or broadcast schemes and most of the multicast protocols [5, 6, 7] are reactive in the sense that they transmit data in response to the user requests. In multicast protocols, users can have the possibility to share the same stream of data as much as possible. While some of the multicast approaches can provide immediate service and save server bandwidth by avoiding unnecessary transmission of data, they are subject to data loss and cannot guarantee on time delivery of data if user requests are bursty or too high. Broadcasting protocols can address this problem by periodically transmitting video segment in a proactive way and guarantee service latency within certain amount of time. To provide VOD services, many VOD Periodic Broadcasting (PB) protocols have been proposed such as Staggered Broadcast [8], skyscraper [9] Harmonic Broadcasting [10] and Fast Data Broadcasting [11], etc. The main idea of the PB protocols is 319
Saleh Ali Alomari et all. / AWERProcedia Information Technology & Computer Science (2012) 318-326
to partition the video into several segments and broadcast each segment periodically on dedicated server channels. While a user is playing the current video segment, it is guaranteed that the next segment is downloaded on time and the whole video can be played out continuously. In this case, the user will have to wait for the occurrence of the first segment before they can start playing the video. The user waiting time is usually the length of the first segment. 2.2. Staggered Broadcast (SB) Protocol Staggered Broadcasting (SB) [12, 13] is the earliest and simplest broadcasting scheme. In the SB, the starting times for the video program evenly cross K server channels. In Figure 1, depicted the number of server channels and how is the process of the broadcasting on the channels. As shown, if the first channel starts broadcasting video in the playback rate b at time T0, the second channel starts broadcasting the same video at time T0 + V/K, the third channel at time T0 + 2V/K, and so on. The difference in the starting times, V/K is known as the phase offset/shifts. Since a new stream of video program has started at every phase offset, it is the time that any client needs to wait for this video to playback. Furthermore, the SB protocol could be implement as follows; the video can be divided into K segments (Seg1, Seg2, Seg3, …, SegK), each of segments have equal size, the duration of each segment or the client access latency is V/K, where V is the duration of the whole video. And every channel Channeli, 1
