In this thesis, when we refer end systems in application layer and network layer as peers and nodes respectively. In a cross layer scheme, round-trip delay time (RTT) value in network layer is passed through the other layers to application layer. RTT value is a key factor for peer management.
A cross layer technique is advantageous to Ring overlay in application layer, because we use peers to mange nodes in MANET. Moreover, P2P system is popular with scalability, fault-tolerance, and self-organization, similar with ad hoc network. Every peer receives some useful information from network and MAC layer so that peers only keep the information of the front peer and rear peer. We form Ring overlay into a logical circle shape that makes the data transmission efficient and smooth.
Though we want to combine two layers (network layer and application layer) technique so as to work together, these two layers have quite different capability. There are three layers between application and network layer, so we make these two layers communicate with each other directly in an effective way by designing a cross layer scheme.
As a result, the management of peer is simple and efficient, and also streaming application can be a true real-time when transmitting data across the MANET. The contribution of this
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thesis is to develop a quality (user’s sense) real-time streaming application in MANET completely.
According to the introduction of our scheme, we expect to achieve some important goals as follows:
1. Reducing the rate of packet loss and shortening the data transmitting delay make users senseless of this drawback.
2. Analyze the suitable number of peers that move in a fixed area or building.
3. Decide the best moment of processing the “maintaining Ring overlay” procedure.
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Chapter2 Related Work
When it comes to streaming, Skype [2] is a quality P2P application comparing with other protocols. A number of studies have been devoted to bringing P2P file sharing protocols into ad hoc networks. Many of these studies are mainly conceptual, presenting architectural proposals but not evaluating them [28, 32, 34, 35, 36, 42]. Majority of studies tried to evaluate the performance of P2P file sharing over MANETs using Gnutella, Chord, Pastry, Free pastry and BitTorrent, respectively [27, 29, 36, 38, 39, 40] or proposed their own P2P file sharing algorithms [4, 30, 31, 33, 37, 41]. Minority of studies have been aware of P2P streaming over MANET.
In [9], P2P streaming over MANET really makes the streaming application efficient.
Nevertheless, mesh is a kind of existing basic P2P overlay. Many characters, advantages, and techniques are quite similar with our scheme. The applications both based on P2P networks though the users are distributed. Streaming application is applied on MANET for user’s mobility. Moreover, cross layer scheme is used in managing the network in our scheme. To produce a quality streaming with smooth mobility is the most important common interest.
Recently, the synergy between MANETs and P2P networks was very popular. P2P network has been researched widely, and many P2P systems are applied for researchers to share files [10, 11] or multimedia live streaming [12, 13] over the Internet. P2P can be classified into two kinds of applications as follows:
1. P2P file sharing, for example：Gnutella [16], BitTorrent [10], Chord [17], Pastry [18], Free-Pastry [19], KaZaA [20], and Tapestry [21]
2. P2P streaming application, for example：PPlive [12], Sopcast [22], Joost [23],
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Coolstreaming [24], Peercast [25], and Zattoo [26]
Thus it can be seen that P2P network protocol has been studied intensively by many researchers. On the other hand, wireless network is also a active topic that attracts quite a bit of researchers to work on. Ad hoc network is one of a representative work of wireless network protocols. The routing protocol in ad hoc networks can be probably classified into the following types:
1. Proactive (table-driven) protocol periodically distributes routing table to maintain the routing paths of node and new lists of destinations. For instance, Destination Sequenced Distance Vector Routing (DSDV), Cluster-Head Gateway Switch Routing (CGSR), and Wireless Routing Protocol (WRP) belong to this type of protocol.
2. Reactive (on-demand) protocol finds a routing path on demand by flooding Route Request packets in the networks. For example, Ad hoc On-Demand Distance Vector Routing (AODV), Dynamic Source Routing (DSR), Temporally Ordered Routing Algorithm (TORA), Associativity Based Routing (ABR), and Single Stability Routing (SSR) are classified to this type protocol.
3. Hybrid (both proactive and reactive) Protocol combines the advantages of proactive and reactive routing protocol. Zone Routing Protocol (ZRP) and Zone-Based Hierarchical Link State Routing, and Dynamic Group Routing Protocol (DGRP) are this kind of protocol, for instance.
Although there so many variations in these protocols, no matter in P2P overlay or ad hoc routing, all of them have advantages and disadvantages in different opinions. Using the appropriate ad hoc routing protocol for the suitable P2P applica tion is the most important issue. Table.2-1 and Table.2-2 show the classification of P2P applications and ad hoc route, respectively.
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Table 2-1 The classification of P2P application
Application File sharing Streaming application
Operation mode
Download, Upload Audio, Video
Instance Napster, Gnutella, Bit torrent, Chord, Pastry, Free-Pastry, KaZaA, and Tapestry
Skype, PPlive, Sopcast, Joost, Coolstreaming, Peercast, and Zattoo
Table 2-2 Different routing protocol in MANET
Protocol Proactive Reactive Hybrid
Operation
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Chapter3 Proposed Scheme
We propose a new cross-layer scheme to overcome the difficulty of media streaming for P2P network over MANET. In our scheme, all peers self-organize a ring overlay structure to simplify the maintenance of the overlay. We apply the ring scheme to integrate the P2P overlay with the MANET topology. Due to the cross- layer integration, an immediate forwarding with proximity can achieve the low traffic overhead and fasten the in-time data delivery. The ring scheme loads less overhead, every peer in the network just needs to keep the information of the front peer and the rear peer. To construct the ring overlay, the underlay network dynamics, such as the topology and available bandwidth, must be known, such that the cross-layer information can be used for promoting the efficiency of the network. The value of round-trip time (RTT) is passed from the MAC layer to the application layer. The integration of the ring overlay and cross-layer scheme not only makes the system efficient, but also reduces the traffic overhead. As shown in Figure 3-1, we illustrate the fundamental structure to show the up-down stack, and then propose the followings in detail successively.
Figure 3-1 Frame structure of our scheme
Network Stack Our Scheme
Application Layer
Session Layer
Transport Layer
MAC Layer
Media Streaming Ring Overlay
Based on P2P structured
TCP / UDP / RTP
MANET
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