Overlay multi-hop FEC scheme for video streaming

Overlay networks offer promising capabilities for video streaming, due to their support for application-layer processing at the overlay forwarding nodes. In this paper, we focus on the problem of providing lightweight support at selected intermediate overlay forwarding nodes to achieve increased error resilience on a single overlay path for video streaming. We propose a novel overlay multi-hop forward error correction (OM-FEC) scheme that provides FEC encoding/decoding capabilities at intermediate nodes in the overlay path. Based on the network conditions, the end-to-end overlay path is partitioned into segments, and appropriate FEC codes are applied over those segments. Architecturally, this flexible design lies between the end-to-end and hop-by-hop paradigms, and we argue that it is well suited to peer-based overlay networks. We evaluate our work by both simulations and controlled Planet-Lab network experiments. These evaluations show that OM-FEC can outperform a pure end-to-end strategy up to 10–15 dB in terms of video peak signal-to-noise ratio (PSNR), and can be much more efficient than a heavyweight hop-by-hop strategy.     

A reliable overlay video transport protocol for multicast agents in wireless mesh networks

A new video transport protocol for multicast agents in wireless mesh networks (WMNs) is proposed in this paper. The proposed protocol enables a significant reduction in the transmission overhead, while providing reliable communication for its use in multicast applications. This proposed reliable protocol provides a practical approach for an overlay peer‐to‐peer multicast facility supported within the application layer. This obviates the need to give upgraded routers capable of handling multicast broadcasting or modify the existing protocol stack. The protocol tolerates partial losses in multimedia transmissions, while supporting control of the delay sensitivity of such transmissions in WMNs. The key issue in this protocol is the ability to detect packet loss, anticipate retransmission requests, and use the anticipated retransmission requests to transmit the lost packets prior to requests from other receiving agents. The proposed protocol allows for the receiver to determine if retransmission of lost packets is required, ensuring the greatest flexibility needed for a reliable multicast protocol. Copyright © 2009 John Wiley & Sons, Ltd.     

An Adaptive Packet and Block Length Forward Error Correction for Video Streaming Over Wireless Networks

Video streaming over wireless networks is a challenging task due to its high error rate. Forward error correction (FEC) is a popular mechanism to recover lost packets for video streaming. Conventional FEC mechanisms use a whole redundant packet to recover the error source packet, when the packet error occurs with only a few bit errors inside. In this paper, we propose an Adaptive packet and block length FEC (APB-FEC) control mechanism. In order to overcome the high bit error rate, a small packet length reduces the packet error rate and a large FEC block length will enhance the recovery performance. Our proposed APB-FEC can obtain better recovery performance than conventional FEC mechanisms. Hence, APB-FEC can also reduce retransmission overhead. Using extensive emulations, we validate the efficiency of APB-FEC mechanism for video streaming over wireless networks.     

Protocol-independent multicast packet delivery improvement service for mobile Ad hoc networks

This paper addresses the issue of improving multicast packet delivery in mobile ad hoc networks and proposes an adaptive mechanism called Protocol-Independent Packet Delivery Improvement Service (PIDIS) to recover lost multicast packets. PIDIS provides its packet-delivery improvement services to any multicast routing protocol for mobile ad hoc networks by exploiting the mechanism of swarm intelligence to make intelligent decisions about where to fetch the lost multicast packets from. PIDIS is a gossip protocol, and nodes using PIDIS are only concerned with which neighbor nodes to gossip with to recover the most lost packets, rather than which member nodes to gossip with. Thus, it does not rely on membership information in a multicast scenario, which is often difficult to get. PIDIS employs the beneficial aspects of probabilistic routing and adapts well to mobility. PIDIS achieves probabilistic improvement in multicast packet delivery and, unlike other gossip-based schemes, does not need to maintain information about group members from which lost multicast packets are retrieved. Further, the operations of PIDIS do not rely on any underlying routing protocol or primitive, and can be incorporated into any ad hoc multicast routing protocol. We incorporated PIDIS over ODMRP [On-Demand Multicast Routing Protocol in Multihop Wireless Mobile Networks, Kluwer Mobile Networks and Applications, 2000], and compared it against Anonymous Gossip (AG) [International Conference on Distributed Computing Systems (ICDCS 2001) Phoenix, Arizona, April 2001] implemented over ODMRP, and ODMRP itself. Our simulation results show that ODMRP + PIDIS is more efficient and performs better than ODMRP + AG and ODMRP in terms of multicast packet delivery, end-to-end delay, and MAC layer overheads. We attribute the better performance and lower MAC overheads of ODMRP + PIDIS to the efficient gossiping made possible by using the swarm intelligence techniques.     

Multicast routing and bandwidth dimensioning in overlay networks

Multicast services can be provided either as a basic network service or as an application-layer service. Higher level multicast implementations often provide more sophisticated features and can provide multicast services at places where no network layer support is available. Overlay multicast networks offer an intermediate option, potentially combining the flexibility and advanced features of application layer multicast with the greater efficiency of network layer multicast. In this paper, we introduce the multicast routing problem specific to the overlay network environment and the related capacity assignment problem for overlay network planning. Our main contributions are the design of several routing algorithms that optimize the end-to-end delay and the interface bandwidth usage at the multicast service nodes within the overlay network. The interface bandwidth is typically a key resource for an overlay network provider, and needs to be carefully managed in order to maximize the number of users that can be served. Through simulations, we evaluate the performance of these algorithms under various traffic conditions and on various network topologies. The results show that our approach is cost-effective and robust under traffic variations.     

Distributed network embedded FEC for real-time multicast applications in multi-hop wireless networks

Multi-hop wireless networks are becoming popular because of their flexibility and low deployment cost. Emerging technologies such as orthogonal frequency division and multiple in and multiple out have significantly increased the bandwidth of a wireless channel. Further, as device cost decreases, a communication terminal can have multiple radios and transmit/receive data simultaneously, which improves the capacity of a wireless network. This makes the support of real-time multicast applications over multi-hop wireless networks viable and practical. Meanwhile, wireless links are prone to random and burst losses due to multipath fading and cross channel interference, real-time multicast over a wireless network remains a challenging problem. Traditional end-to-end FEC is less efficient in multi-hop wireless networks, as packets may suffer from random or burst losses in more than one hop before they arrive at their destination. In this paper, we advocate the deployment of distributed network-embedded FEC (DNEF) for real-time multicast distribution over multi-hop wireless networks. We first develop a packet loss model of multi-hop wireless networks using a system analysis approach. We then propose a distributed codec placement algorithm and evaluate its performance. Our simulation shows that multicast using DNEF significantly outperforms both traditional multicast and application-level peer-to-peer multicast that can be deployed over multi-hop wireless networks.     

The design, implementation, and performance evaluation of theon-demand multicast routing protocol in multihop wireless networks

Multicasting has emerged as one of the most focused areas in the field of networking. As the technology and popularity of the Internet grow, applications such as video conferencing that require the multicast feature are becoming more widespread. Another interesting development has been the emergence of dynamically reconfigurable wireless ad hoc networks to interconnect mobile users for applications ranging from disaster recovery to distributed collaborative computing. In this article we describe the on-demand multicast routing protocol for mobile ad hoc networks. ODMRP is a mesh-based, rather than conventional tree-based, multicast scheme and uses a forwarding group concept (only a subset of nodes forwards the multicast packets packets via scoped flooding). It applies on-demand procedures to dynamically build routes and maintain multicast group membership. We also describe our implementation of the protocol in a real laptop testbed     

Exploring the design space of reliable multicast protocols for wireless mesh networks

Many important applications in wireless mesh networks require reliable multicast communication, i.e., with 100% packet delivery ratio (PDR). Previously, numerous multicast protocols based on automatic repeat request (ARQ) have been proposed to improve the packet delivery ratio. However, these ARQ-based protocols can lead to excessive control overhead and drastically reduced throughput. In this paper, we present a comprehensive exploration of the design space for developing high-throughput, reliable multicast protocols that achieve 100% PDR.Motivated by the fact that 802.11 MAC layer broadcast, which is used by most wireless multicast protocols, offers no reliability, we first examine if better hop-by-hop reliability provided by unicasting the packets at the MAC layer can help to achieve end-to-end multicast reliability. We then turn to end-to-end solutions at the transport layer. Previously, forward error correction (FEC) techniques have been proved effective for providing reliable multicast in the Internet, by avoiding the control packet implosion and scalability problems of ARQ-based protocols. In this paper, we examine if FEC techniques can be equally effective to support reliable multicast in wireless mesh networks. We integrate four representative reliable schemes (one ARQ, one FEC, and two hybrid) originally developed for the Internet with a representative multicast protocol ODMRP and evaluate their performance.Our experimental results via extensive simulations offer an in-depth understanding of the various choices in the design space. First, compared to broadcast-based unreliable ODMRP, using unicast for per-hop transmission only offers a very small improvement in reliability under low load, but fails to improve the reliability under high load due to the significantly increased capacity requirement which leads to congestion and packet drop. Second, at the transport layer, the use of pure FEC can significantly improve the reliability, increasing PDR up to 100% in many cases, but can be inefficient in terms of the number of redundant packets transmitted. In contrast, a carefully designed ARQ–FEC hybrid protocol, such as RMDP, can also offer 100% reliability while improving the efficiency by up to 38% compared to a pure FEC scheme. To our best knowledge, this is the first in-depth study of high-throughput, reliable multicast protocols that provide 100% PDR for wireless mesh networks.     

A Framework for Mitigating Attacks Against Measurement-Based Adaptation Mechanisms in Unstructured Multicast Overlay Networks

Many multicast overlay networks maintain application-specific performance goals by dynamically adapting the overlay structure when the monitored performance becomes inadequate. This adaptation results in an unstructured overlay where no neighbor selection constraints are imposed. Although such networks provide resilience to benign failures, they are susceptible to attacks conducted by adversaries that compromise overlay nodes. Previous defense solutions proposed to address attacks against overlay networks rely on strong organizational constraints and are not effective for unstructured overlays. In this work, we identify, demonstrate and mitigate insider attacks against measurement-based adaptation mechanisms in unstructured multicast overlay networks. We propose techniques to decrease the number of incorrect adaptations by using outlier detection and limit the impact of malicious nodes by aggregating local information to derive global reputation for each node. We demonstrate the attacks and mitigation techniques through real-life deployments of a mature overlay multicast system.      

Source-adaptive multilayered multicast algorithms for real-timevideo distribution

Layered transmission of data is often recommended as a solution to the problem of varying bandwidth constraints in multicast video applications. Multilayered encoding, however, is not sufficient to provide high video quality and high network utilization, since bandwidth constraints frequently change over time. Adaptive techniques capable of adjusting the rates of video layers are required to maximize video quality and network utilization. We define a class of algorithms known as source-adaptive multilayered multicast (SAMM) algorithms. In SAMM algorithms, the source uses congestion feedback to adjust the number of generated layers and the bit rate of each layer. We contrast two specific SAMM algorithms: an end-to-end algorithm, in which only end systems monitor available bandwidth and report the amount of available bandwidth to the source, and a network-based algorithm, in which intermediate nodes also monitor and report available bandwidth. Using simulations that incorporate multilayered video codecs, we demonstrate that SAMM algorithms can exhibit better scalability and responsiveness to congestion than algorithms that are not source-adaptive. We also study the performance trade-offs between end-to-end and network-based SAMM algorithms     

NER-DRP: Dissemination-based Routing Protocol with Network-layer Error Control for Intermittently Connected Mobile Networks

Reliable transmission in Intermittently Connected Mobile Networks (ICMNs) is a challenging work because the effective and reliable connection between the source and the destination can not be sustained. To reliably hand over data packets to the destination, many dissemination-based routing protocols are proposed. Dissemination-based routing protocols assure nodes including intermediate nodes and destinations have more chances to receive packets, which will increase the probability that the packets can be correctly received by the destination. However, the existing error recovery mechanisms in network layer use the simple CRC to check the data packets independently, and discard the error packets even if one correct packet can be obtained from more than one partly error packets. In this paper, first we propose a novel Network layer Error Recovery method (abbreviated as NER) based on Forward Error Correction (FEC). NER divides a data packet into Reed Solomon (RS) blocks and insert redundancy to each block. So the intermediate nodes and destinations can recover a correct data packet from multiple partially error copies of the same packet. Then we propose a novel routing protocol named NER-DRP based on the Epidemic routing and NER, which can improve the performance of ICMNs in terms of delivery ratio, end-to-end delay and count of hops.     

Minimizing Intermediate Multicast routing for dynamic multi-hop ad hoc networks

A Minimizing Intermediate Multicast Routing protocol （MIMR） is proposed for dynamic multi-hop ad hoc networks. In MIMR, multicast sessions are created and released only by source nodes. In each multicast session process, the source node keeps a list of intermediate nodes and destinations, which is encapsulated into the packet header when the source node sends a multicast packet. Nodes receiving multicast packets decide to accept or forward the packet according to the list. Depending on topology matrix maintained by unicast routing, the shortest virtual hierarchy routing tree is constructed by improved Dijkstra algorithm. MIMR can achieve the minimum number of intermediate nodes, which are computed through the tree. No control packet is transmitted in the process of multicast session. Load of the network is largely decreased. Experimental result shows that MIMR is flexible and robust for dynamic ad hoc networks.     

Random linear network coding with ladder-shaped global coding matrix for robust video transmission

Robust video multicast in erasure networks using network coding (NC) to reduce the impact of packet loss is studied in this paper. In our proposed solution, random linear network coding (RLNC) is adopted at intermediate nodes of the network. RLNC linearly combines a group of packets by randomly selecting weighting coefficients on a finite field, and the loss of an RLNC-coded packet is equivalent to the loss of one constraint in a linear system of equations required for RLNC decoding. Unless the global coding coefficient matrix, or simply called the global coding matrix (GCM), is of full rank, a receive node cannot reconstruct all source packets. To address this rank deficiency problem, we propose to construct a special-structured GCM, called the ladder-shaped GCM (LGCM), for layered H.264/SVC (scalable video coding) video multicast. The ladder shape of the sparse coding matrix is maintained throughout the RLNC process to achieve two objectives: (1) to enable partial decoding of a block; and (2) to provide unequal erasure protection for H.264/SVC priority layers. Furthermore, quality degradation is minimized by optimizing the amount of redundancy assigned to each layer, and graceful quality degradation is achieved by error concealment (EC). Simulation results are given to demonstrate the superior performance of the proposed RLNC–LGCM scheme over the traditional RLNC with a generalGCM.     

Application-layer multicasting with Delaunay triangulation overlays

Application-layer multicast supports group applications without the need for a network-layer multicast protocol. Here, applications arrange themselves in a logical overlay network and transfer data within the overlay. We present an application-layer multicast solution that uses a Delaunay triangulation as an overlay network topology. An advantage of using a Delaunay triangulation is that it allows each application to locally derive next-hop routing information without requiring a routing protocol in the overlay. A disadvantage of using a Delaunay triangulation is that the mapping of the overlay to the network topology at the network and data link layer may be suboptimal. We present a protocol, called Delaunay triangulation (DT protocol), which constructs Delaunay triangulation overlay networks. We present measurement experiments of the DT protocol for overlay networks with up to 10 000 members, that are running on a local PC cluster with 100 Linux PCs. The results show that the protocol stabilizes quickly, e.g., an overlay network with 10 000 nodes can be built in just over 30 s. The traffic measurements indicate that the average overhead of a node is only a few kilobits per second if the overlay network is in a steady state. Results of throughput experiments of multicast transmissions (using TCP unicast connections between neighbors in the overlay network) show an achievable throughput of approximately 15 Mb/s in an overlay with 100 nodes and 2 Mb/s in an overlay with 1000 nodes.     

Dynamic Rate and FEC Adaptation for Video Multicast in Multi-rate Wireless Networks

Video multicast over Wireless Local Area Networks (WLANs) faces many challenges due to varying channel conditions and limited bandwidth. A promising solution to this problem is the use of packet level Forward Error Correction (FEC) mechanisms. However, the adjustment of the FEC rate is not a trivial issue due to the dynamic wireless environment. This decision becomes more complicated if we consider the multi-rate capability of the existing wireless LAN technology. In this paper, we propose a novel method which dynamically adapts the transmission rate and FEC for video multicast over multi-rate wireless networks. In order to evaluate the system experimentally, we implemented a prototype using open source drivers and socket programming. Our experimental results show that the proposed system significantly improves the multicast system performance.     

Maximizing multicast lifetime in unreliable wireless ad hoc network

Multicast is an efficient method for transmitting the same packets to a group of destinations. In energy-constrained wireless ad hoc networks where nodes are powered by batteries, one of the challenging issues is how to prolong the multicast lifetime. Most of existing work mainly focuses on multicast lifetime maximization problem in wireless packet loss-free networks. However, this may not be the case in reality. In this paper, we are concerned with the multicast lifetime maximization problem in unreliable wireless ad hoc networks. To solve this problem, we first define the multicast lifetime as the number of packets transmitted along the multicast tree successfully. Then we develop a novel lifetime maximization genetic algorithm to construct the multicast tree consisting of high reliability links subject to the source and destination nodes. Simulation results demonstrate the efficiency and effectiveness of the proposed algorithm.     

An altruistic cross‐layer recovering mechanism for ad hoc wireless networks

Video streaming services have restrictive delay and bandwidth constraints. Ad hoc networks represent a hostile environment for this kind of real‐time data transmission. Emerging mesh networks, where a backbone provides more topological stability, do not even assure a high quality of experience. In such scenario, mobility of terminal nodes causes link breakages until a new route is calculated. In the meanwhile, lost packets cause annoying video interruptions to the receiver. This paper proposes a new mechanism of recovering lost packets by means of caching overheard packets in neighbor nodes and retransmit them to destination. Moreover, an optimization is shown, which involves a video‐aware cache in order to recover full frames and prioritize more significant frames. Results show the improvement in reception, increasing the throughput as well as video quality, whereas larger video interruptions are considerably reduced. Copyright © 2014 John Wiley & Sons, Ltd.     

A novel overlay multicast protocol in mobile ad hoc networks: design and evaluation

Despite significant research in mobile ad hoc networks, multicast still remains a research challenge. Recently, overlay multicast protocols for MANET have been proposed to enhance the packet delivery ratio by reducing the number of reconfigurations caused by nongroup members' unexpected migration in tree or mesh structure. However, since data is delivered by using replication at each group member, delivery failure on one group member seriously affects all descendent members' packet delivery ratio. In addition, delivery failure can occur by collision between numbers of unicast packets where group members densely locate. In this paper, we propose a new overlay multicast protocol to enhance packet delivery ratio in two ways. One is to construct a new type of overlay data delivery tree, and the other is to apply a heterogeneous data forwarding scheme depending on the density of group members. While the former aims to minimize influence of delivery failure on one group member, the latter intends to reduce excessive packet collision where group members are densely placed. Our simulation results show distinct scalability improvement of our approach without regard to the number of group members or source nodes.     

A Reliable Multicast Routing Protocol Based on Recovery Points and FEC in Mobile Ad-hoc Networks

Multicasting is an essential service for mobile ad-hoc networks. A major challenge for multicasting in mobile ad-hoc networks (MANETs) is the unstable forwarding path. This work presents a reliable multicasting protocol for mobile ad-hoc networks. A virtual backbone is used as a shared structure for multiple sessions. A lost packet recovery scheme is developed for reliable packet transmission, called the Recovery Point (RP) scheme. The RP scheme maintains the data packets received from the source for recovering lost packets for its downstream RPs. In addition, we combine the Forward Error Correction (FEC) technology with our RP scheme to enhance the reliability of our RP scheme. A mergence scheme for RP is also proposed to avoid excessive control overhead. Our RP and FEC based scheme can be used to improve the reliability and efficiency of the traditional non-acknowledged multicasting approach. Experiments were conducted to evaluate the proposed multicasting scheme. The results demonstrate that our scheme outperforms other schemes in terms of packet delivery ratio and multicast efficiency. Furthermore, the simulation results also demonstrate that our approach is stable in networks with high mobility.

An efficient heterogeneous key management approach for secure multicast communications in ad hoc networks

In a mobile wireless ad hoc network, mobile nodes cooperate to form a network without using any infrastructure such as access points or base stations. Instead, the mobile nodes forward packets for each other, allowing communication among nodes outside wireless transmission range. As the use of wireless networks increases, security in this domain becomes a very real concern. One fundamental aspect of providing confidentiality and authentication is key distribution. While public-key encryption has provided these properties historically, ad hoc networks are resource constrained and benefit from symmetric key encryption. In this paper, we propose a new key management mechanism to support secure group multicast communications in ad hoc networks. The scheme proposes a dynamic construction of hierarchical clusters based on a novel density function adapted to frequent topology changes. The presented mechanism ensures a fast and efficient key management with respect to the sequential 1 to n multicast service.