VOD STREAMING WITH A NETWORK CODING EQUIVALENT CONTENT DISTRIBUTION SCHEME

Although random access operations are desirable for on-demand video streaming in peer-to-peer systems, they are difficult to efficiently achieve due to the asynchronous interactive behaviors of users and the dynamic nature of peers. In this paper, we propose a network coding equivalent content distribution (NCECD) scheme to efficiently handle interactive videoon- demand (VoD) operations in peer-to-peer systems. In NCECD, videos are divided into segments that are then further divided into blocks. These blocks are encoded into independent blocks that are distributed to different peers for local storage. With NCECD, a new client only needs to connect to a sufficient number of parent peers to be able to view the whole video and rarely needs to find new parents when performing random access operations. In most existing methods, a new client must search for parent peers containing specific segments; however, NCECD uses the properties of network coding to cache equivalent content in peers, so that one can pick any parent without additional searches. Experimental results show that the proposed scheme achieves low startup and jump searching delays and requires fewer server resources. In addition, we present the analysis of system parameters to achieve reasonable block loss rates for the proposed scheme

The state of peer-to-peer network simulators

Networking research often relies on simulation in order to test and evaluate new ideas. An important requirement of this process is that results must be reproducible so that other researchers can replicate, validate and extend existing work. We look at the landscape of simulators for research in peer-to-peer (P2P) networks by conducting a survey of a combined total of over 280 papers from before and after 2007 (the year of the last survey in this area), and comment on the large quantity of research using bespoke, closed-source simulators. We propose a set of criteria that P2P simulators should meet, and poll the P2P research community for their agreement. We aim to drive the community towards performing their experiments on simulators that allow for others to validate their results

Network Coding based Information Security in Multi-hop Wireless Networks

Multi-hop Wireless Networks (MWNs) represent a class of networks where messages are forwarded through multiple hops of wireless transmission. Applications of this newly emerging communication paradigm include asset monitoring wireless sensor networks (WSNs), command communication mobile ad hoc networks (MANETs), community- or campus-wide wireless mesh networks (WMNs), etc. Information security is one of the major barriers to the wide-scale deployment of MWNs but has received little attention so far. On the one hand, due to the open wireless channels and multi-hop wireless transmissions, MWNs are vulnerable to various information security threats such as eavesdropping, data injection/modification, node compromising, traffic analysis, and flow tracing. On the other hand, the characteristics of MWNs including the vulnerability of intermediate network nodes, multi-path packet forwarding, and limited computing capability and storage capacity make the existing information security schemes designed for the conventional wired networks or single-hop wireless networks unsuitable for MWNs. Therefore, newly designed schemes are highly desired to meet the stringent security and performance requirements for the information security of MWNs. In this research, we focus on three fundamental information security issues in MWNs: efficient privacy preservation for source anonymity, which is critical to the information security of MWNs; the traffic explosion issue, which targets at preventing denial of service (DoS) and enhancing system availability; and the cooperative peer-to-peer information exchange issue, which is critical to quickly achieve maximum data availability if the base station is temporarily unavailable or the service of the base station is intermittent. We have made the following three major contributions. Firstly, we identify the severe threats of traffic analysis/flow tracing attacks to the information security in network coding enabled MWNs. To prevent these attacks and achieve source anonymity in MWNs, we propose a network coding based privacy-preserving scheme. The unique “mixing” feature of network coding is exploited in the proposed scheme to confuse adversaries from conducting advanced privacy attacks, such as time correlation, size correlation, and message content correlation. With homomorphic encryption functions, the proposed scheme can achieve both privacy preservation and data confidentiality, which are two critical information security requirements. Secondly, to prevent traffic explosion and at the same time achieve source unobservability in MWNs, we propose a network coding based privacy-preserving scheme, called SUNC (Source Unobservability using Network Coding). Network coding is utilized in the scheme to automatically absorb dummy messages at intermediate network nodes, and thus, traffic explosion induced denial of service (DoS) can be naturally prevented to ensure the system availability. In addition to ensuring system availability and achieving source unobservability, SUNC can also thwart internal adversaries. Thirdly, to enhance the data availability when a base station is temporarily unavailable or the service of the base station is intermittent, we propose a cooperative peer-to-peer information exchange scheme based on network coding. The proposed scheme can quickly accomplish optimal information exchange in terms of throughput and transmission delay. For each research issue, detailed simulation results in terms of computational overhead, transmission efficiency, and communication overhead, are given to demonstrate the efficacy and efficiency of the proposed solutions

Efficient search and scheduling in P2P-based media-on-demand streaming service

We are interested in providing a media-on-demand streaming service to a large population of clients using a peer-to-peer approach. Since the demands of different clients are asynchronous and the contents of clients' buffers are continuously changing, finding partners with expected data and collaborating with them for future content delivery are very important and challenging problems. In this paper, we propose a generic buffer-assisted search (BAS) scheme to improve partner search efficiency by reducing the size of index overlay. We have also developed a novel scheduling algorithm based on deadline-aware network coding (DNC) to fully exploit network resources by dynamically adjusting the coding window size. Extensive simulation results demonstrate that BAS can provide a faster response time with less control cost than the existing search methods, and DNC improves the network capacity utilization and provides high streaming quality under different network conditions