Packet-level Forward Error Correction Research Articles

Network Coded Constrained Application Protocol With Improved Energy Efficiency for IIoT Networks

Constrained Application Protocol (CoAP) for low-power low-rate data transport in Industrial Internet of Things (IIoT) networks is typically running with two modes, namely, confirmable mode and non-confirmable mode, respectively. Confirmable mode relies on retransmission to ensure a guaranteed Quality of Service (QoS) in terms of packet loss rate at the cost of increased latency and power consumption. Whereas non-confirmable mode consumes less power, it is known to be packet loss prone. To enrich the CoAP transport for IIoT networks, we propose a packet-level Forward Error Correction (FEC) mechanism based on systematic coding with adaptive code rate to provide energy-efficient and reliable packet delivery. We mathematically analyze packet loss and cost of energy consumption of the proposed mechanism and compare it with confirmable CoAP transport scheme in the Gilbert-Elliott channel model. We demonstrate that the proposed mechanism can enhance the performance of non-confirmable CoAP to be comparable to confirmable CoAP in terms of packet loss rate, while outperforming it in energy consumption. The analytical and simulation results verify that the proposed mechanism is suitable for IIoT networks especially in high erasure burstiness scenarios.

Joint Link Rate Selection and Adaptive Forward Error Correction for High-Rate Wireless Multicast

Multicast communication over wireless networks has many potential applications, such as real-time audiovisual content distribution or digital signage systems with multiple remote terminals. However, today’s common 802.11 networks cannot fully support such applications at the link layer due to the technical challenges in achieving both high transmission rate and high reliability for multicast data transfers. Those challenges primarily emerge from the inapplicability of immediate acknowledgment mechanisms of unicast transmissions to the multicast case and the need for finding a common transmission rate for all receivers with diverse channel conditions. The research literature in this domain mainly addresses the problem at the higher layers of the protocol stack. In this article, we present a novel approach that combines wireless link rate selection with an adaptive packet-level Forward Error Correction (FEC) mechanism in order to achieve high-rate and highly reliable multicast in 802.11 wireless networks. The integration of FEC into the 802.11 MAC layer allows direct interaction between the transmission rate and the coding scheme. As a result, potential packet losses caused by higher link rates can be compensated by the adjustable redundancy provided by FEC. In combination with an aggregated receiver feedback mechanism, this yields improved transmission efficiency and reliability for wireless multicast. We investigate this approach in a simulation environment under a realistic wireless channel model in various application scenarios with up to 50 receivers. The results represent significant performance improvements, in terms of throughput, channel utilization, and packet loss, over the state-of-the-art methods for reliable wireless multicast.

The HOP Protocol: Reliable Latency-Bounded End-to-End Multipath Communication

Next-generation wireless networks are expected to enable new applications with strict latency constraints. However, existing transport layer protocols are unable to meet the stringent Quality of Service (QoS) requirements on throughput and maximum latency: excessive queuing due to capacity-oriented congestion control inflates end-to-end latency well beyond interactivity deadlines. In this work, we propose a novel framework that evolves best-effort communications into reliability- and latency-aware communications for QoS-sensitive applications. The new protocol, named High-reliability latency-bounded Overlay Protocol (HOP), provides a novel combination of packet-level Forward Error Correction (FEC) and multipath scheduling to compensate for capacity drops and meet pre-defined QoS requirements. More specifically, the sender splits the data and the associated redundancy between the paths by using a stochastic forecast of their future capacity and decides the amount of redundancy necessary to meet the application’s requirements without clogging the connections. We compare HOP’s performance with state-of-the-art multipath protocols in ns-3 simulations using both synthetic and live network traces, and confirm that our scheme can reliably deliver high-throughput data, reducing the number of late blocks by 2 to 5 times with respect to optimized Multipath TCP (MPTCP).

Minimum-Latency FEC Design With Delayed Feedback: Mathematical Modeling and Efficient Algorithms

In this paper, we consider the packet-level forward error correction (FEC) code design, without feedback or with delayed feedback, for achieving the minimum end-to-end latency, i.e., the latency between the time when packet is generated at the source and its \emph{in-order delivery} to the application layer of the destination. We first show that the minimum-latency FEC design problem can be modeled as a partially observable Markov decision process (POMDP), and hence the optimal code construction can be obtained by solving the corresponding POMDP. However, solving the POMDP optimally is in general difficult unless the size is very small. To this end, we propose an efficient heuristic algorithm, namely the majority vote policy, for obtaining a high quality approximate solution. We also derive the tight lower and upper bounds of the optimal state values of this POMDP, based on which a more sophisticated D-step search algorithm is implemented for obtaining near-optimal solutions. The simulation results show that the proposed code designs via solving the POMDP, either with the majority vote policy or the D-step search algorithm, strictly outperform the existing schemes, in both cases, without or with only delayed feedback.

Erasure Codes Based Adaptive Multi-hop Reliable Data Transfer for Underwater Acoustic Sensor Networks

Development of efficient techniques for improving data transmission reliability is a major concern in the design of underwater acoustic sensor networks (UWASNs). In this paper, we propose an erasure code based multi-hop reliable data transfer scheme (ECRDT) for UWASNs. ECRDT is essentially a packet level forward error correction scheme based on either end-to-end erasure coding or hop-by-hop erasure coding. In the end-to-end approach, encoding and decoding are performed by the source node and sink node, respectively, while intermediate nodes just forward the data packets without any processing. The hop-by-hop erasure coding achieves per hop reliable data transfer along the multi-hop path. In this case, apart from the source node, all intermediate nodes perform encoding process and each node is required to adaptively compute the number of redundant packets for the next hop based on the quality of the corresponding hop. We present an analytical model to find the communication overhead, energy consumption and average delay of the multi-hop UWASN under the above erasure coding approaches. Simulation and analytical results show that the proposed ECRDT scheme based on hop-by-hop erasure coding can significantly reduce communication overhead, energy consumption and average delay.

Wireless Video Multicast With Cooperative and Incremental Transmission of Parity Packets

In this paper, a cooperative multicast scheme that uses Randomized Distributed Space Time Codes (R-DSTC), along with packet level Forward Error Correction (FEC), is studied. Instead of sending source packets and/or parity packets through two hops using R-DSTC as proposed in our prior work, the new scheme delivers both source packets and parity packets using only one hop. After the source station (access point, AP) first sends all the source packets, the AP as well as all nodes that have received all source packets together send the parity packets using R-DSTC. As more parity packets are transmitted, more nodes can recover all source packets and join the parity packet transmission. The process continues until all nodes acknowledge the receipt of enough packets for recovering the source packets. For each given node distribution, the optimum transmission rates for source and parity packets are determined such that the video rate that can be sustained at all nodes is maximized. This new scheme can support significantly higher video rates, and correspondingly higher PSNR of decoded video, than the prior approaches. Three suboptimal approaches, which do not require full information about user distribution or the feedback, and hence are more feasible in practice are also presented. The proposed suboptimal scheme with only the node count information and without feedback still outperforms our prior approach that assumes full channel information and no feedback.

On elastic traffic via contention resolution diversity slotted aloha satellite access

SummaryThis paper presents a performance study relative to the coupling of the Transmission Control Protocol (TCP) with the Contention Resolution Diversity slotted aloha (CRDSA) protocol, in the case of greedy TCP connections (also called elephants) on Digital Video Broadcasting‐Return Channel via a geostationary satellite. CRDSA, which takes advantage of interference cancellation algorithms for collision/contention resolution, has already exhibited interesting performance when the power levels of all received bursts are perfectly balanced. In this paper, we extend the study to a more realistic case, where a certain spreading of the bursts' power levels is taken into account. The consequent capture effect even facilitates the collision resolution mechanism and yields an improvement in the overall TCP performance with respect to the balanced case. Furthermore, in certain conditions, the adoption of packet level forward error correction allows achieving even higher peaks of throughput than the expected ones. Copyright © 2014 John Wiley & Sons, Ltd.

Enabling a Bufferless Core Optical Network Using Edge-to-Edge Packet-Level FEC

To cope with the phenomenal growth of the Internet over the next decade, core networks are expected to scale to capacities of terabits-per-second and beyond. Increasing the role of optics for switching and transmission inside the core network seems to be the most promising way forward to accomplish this capacity scaling. Unfortunately, unlike electronic memory, it remains a formidable challenge to build even a few packets of integrated all-optical buffers. In this context, we envision a bufferless (or near-zero buffer) core optical network and make three contributions: First, we propose a novel edge-to-edge based packet-level forward error correction (FEC) scheme that combats packet loss in the bufferless core, and characterise the impact of FEC strength on loss at a single link. Second, we develop a global optimisation framework for multi-hop networks, and propose a heuristic algorithm that adjusts FEC strength to achieve fairness amongst the different single- and multi-hop flows. Finally, we evaluate the performance of our FEC scheme for realistic mixes of short- and long-lived TCP flows, and show that edge-to-edge packet-level FEC can be tuned to effectively mitigate contention losses in the core, thus opening the doors to bufferless optical networks in the near future.

Packet-level Forward Error Correction: 1-D Interleaved Parity Codes

Packet-level Forward Error Correction: 1-D Interleaved Parity Codes

A collision avoidance scheme for the synchronized broadcast packets in a multi-AP Wi-Fi broadcasting system

A Wi-Fi broadcasting system is a kind of Mobile-TV system that transmits multimedia content over Wi-Fi networks. The specialty of the system is that it takes advantage of broadcast packets for streaming to be scalable to the number of users. However, the loss rate of broadcast packets is much higher than that of unicast ones because MAC layer retransmission is not applied on broadcast packets. To recover lost packets, a packet level Forward Error Correction (FEC) scheme is usually used in Wi-Fi broadcasting systems. But it introduces additional transmission overhead, which is usually proportional to the packet loss rate. So it is important to reduce the packet loss rate to build an efficient and reliable Wi-Fi broadcasting system. While past studies have considered only single-AP systems, our study focuses on a multi-AP system which is designed to cover a much larger area. We found a specific packet collision problem that increases packet loss rate significantly in a multi-AP system. It is caused by the simultaneous arrival and transmission of a broadcast packet at and by APs. We identify two scenarios of the collision that depend on the channel state at the time of packet arrival. We propose two collision avoidance methods to handle these scenarios: Broadcast Packet Scheduling Method (BPSM) and Adaptive Contention Window-Sizing Method(ACWSM). We implement both methods in our multi-AP Wi-Fi broadcasting system and verify their effectiveness through experiments.

Cooperative Layered Video Multicast Using Randomized Distributed Space Time Codes

With the increased popularity of mobile multimedia services, efficient and robust video multicast strategies are of critical importance. Cooperative communications has been shown to improve the robustness and the data rates for point-to-point transmission. In this paper, a two-hop cooperative transmission scheme for multicast in infrastructure-based networks is used, where multiple relays forward the data simultaneously using randomized distributed space time codes (RDSTC). This randomized cooperative transmission is further integrated with layered video coding and packet level forward error correction (FEC) to enable efficient and robust video multicast. Three different schemes are proposed to find the system operating parameters based on the availability of the channel information at the source station: RDSTC with full channel information, RDSTC with limited channel information, and RDSTC with node count. The performance of these three schemes are compared with rate adaptive direct transmission and conventional multicast that does not use rate adaptation. The results show that while rate-adaptive direct transmission provides better video quality than conventional multicast, all three proposed randomized cooperative schemes outperform both strategies significantly as long as the network has enough nodes. Furthermore, the performance gap between RDSTC with full channel information and RDSTC with limited channel information or node count is relatively small, indicating the robustness of the proposed cooperative multicast system using RDSTC.

Performance evaluation of AL-FEC LDPC codes for push content applications in wireless unidirectional environments

FEC (Forward Error Correction) mechanisms improve IP content transmission reliability through the recovery of packets lost in transmission. Opposite to ARQ (Automatic Repeat Request), FEC mechanisms are especially suited to unidirectional environments or to multicast environments where multiple receivers perceived different channel losses, thus making difficult the implementation of mechanisms based on feedback information. Among the different types of FEC codes, this paper presents a thorough performance evaluation of LDPC (Low Density Parity Check) codes, based on an implementation developed by the authors, according to the specifications defined by RFC 5170 for the usage of LDPC codes by push content applications based on the FLUTE protocol. LDPC codes provide a good trade-off between performance and complexity, hence, they are appropriate for mobile applications. Contributions of this paper include tests conducted with commercial mobile phones connected to the push content download server over a Wi-Fi network. The evaluation highlights the advantages of using packet level FEC encoding in file transmission over unidirectional networks and provides with a comparison between two kinds of LDPC structures: Staircase and Triangle. This is accomplished by calculating the inefficiency ratio of these LDPC structures in different environments. Results show that the implemented LDPC codes can provide inefficiency ratios close to one when the different coding parameters (as the code rate or the number of blocks) are configured to an optimal value that depends on the packet loss rate.

Extreme value FEC for reliable broadcasting in wireless networks

The advent of practical rateless codes enables implementation of highly efficient packet-level forward error correction (FEC) strategies for reliable data broadcasting in loss-prone wireless networks, such as sensor networks. Yet, the critical question of accurately quantifying the proper amount of redundancy has remained largely unsolved. In this paper, we exploit advances in extreme value theory to rigorously address this problem. Under the asymptotic regime of a large number of receivers, we derive a closed-form expression for the cumulative distribution function (CDF) of the completion time of file distribution. We show the existence of a phase transition associated with this CDF and accurately locate the transition point. We derive tight convergence bounds demonstrating the accuracy of the asymptotic estimate for the practical case of a finite number of receivers. Further, we asymptotically characterize the CDF of the completion time under heterogeneous packet loss, by establishing a close relationship between the data broadcasting and multi-set coupon collector problems. We demonstrate the benefits of our approach through simulation and through real experiments on a Tmote Sky sensor testbed. Specifically, we augment the existing Rateless Deluge software dissemination protocol with an extreme value FEC strategy. The experimental results reveal reduction by a factor of five in retransmission request messages and by a factor of two in total dissemination time, at the cost of a marginally higher number of data packet transmissions in the order of 5%.

Layered Wireless Video Multicast Using Relays

Wireless video multicast enables delivery of popular events to many mobile users in a bandwidth efficient manner. However, providing good and stable video quality to a large number of users with varying channel conditions remains elusive. In this paper, an integration of layered video coding, packet level forward error correction, and two-hop relaying is proposed to enable efficient and robust video multicast in infrastructure-based wireless networks. First, transmission with conventional omni-directional antennas is considered where relays have to transmit in non-overlapping time slots in order to avoid collision. In order to improve system efficiency, we next investigate a system in which relays transmit simultaneously using directional antennas. In both systems, we consider a non-layered configuration, where the relays forward all received video packets and all users receive the same video quality, as well as a layered setup, where the relays forward only the base-layer video. For each system setup, we consider optimization of the relay placement, user partition, transmission rates of each hop, and time scheduling between source and relay transmissions. Our analysis shows that the non-layered system can provide better video quality to all users than the conventional direct transmission system, and the layered system enables some users to enjoy significantly better quality, while guaranteeing other users the same or better quality than direct transmission. The directional relay system can provide substantial improvements over the omni-directional relay system. To support our results, a prototype is implemented using open source drivers and socket programming, and the system performance is validated with real-world experiments.

Dynamical combination of byte level and Sub-Packet level FEC in HARQ mechanism to reduce error recovery overhead on video streaming over wireless networks

Byte level Forward Error Correction (B-FEC) is efficient for recovery from uniform bit errors, but not suitable to handle recovery from burst bit errors. Conversely, Sub-Packet level Forward Error Correction (SP-FEC) can alleviate the problem of large encoding/decoding delay jitter in Packet level Forward Error Correction (P-FEC) to efficiently handle recovery from burst bit errors, but has large error recovery overhead as P-FEC for recovery from uniform bit errors. This paper proposes a dynamic combination of byte level and Sub-Packet level Forward Error Correction (BSP-FEC) in the Hybrid Automatic Repeat reQuest (HARQ) mechanism to reduce the error recovery overhead. BSP-FEC not only can solve the problems appearing in B-FEC and SP-FEC, but also can get the advantages of B-FEC and SP-FEC in the HARQ mechanism. BSP-FEC replaces the SP-FEC checksum with B-FEC and uses Automatic Repeat reQuest (ARQ) when the network condition deteriorates. BSP-FEC not only utilizes an overhead cost model to dynamically decide the SP-FEC parameter and the B-FEC bit rate according to network conditions, but also utilizes a time constraint model to decide the ARQ retry limit. BSP-FEC dynamically adjusts the FEC redundancy to save bandwidth and improves the Decodable Frame Rate (DFR) and the Peak Signal to Noise Ratio (PSNR) of the delivered video streaming. Accordingly, BSP-FEC can improve multimedia communication performance to both avoid network congestion and shorten end-to-end delay by decreasing effective packet loss rate and packet recovery overhead. Because of the low packet recovery overhead, furthermore, BSP-FEC allows applications to transmit more application data in networks with limited bandwidth. Considering the compatibility, BSP-FEC is implemented in the application layer as the end-to-end protection method to protect packets from errors in wired/wireless networks. Numerical and simulation experimental results show that BSP-FEC obtains better recovery efficiency with the minimum error recovery overhead.

Improving performance in the OpMiGua hybrid network employing the network layer packet redundancy scheme

The optical migration-capable network with service guarantees hybrid network is a time-divided packet/circuit hybrid network offering absolute performance guarantees and high resource utilisation. Guaranteed service traffic (GST) follows lightpaths receiving absolute priority over statistically multiplexed (SM) traffic. Transmission resources are fully shared by interleaving SM and GST packets, but packet-switched SM packets experience contention, resulting in a packet loss that should be minimised. This article explores a novel bufferless network approach where the performance of the SM class is satisfied by applying packet-level forward error correction (FEC). Two implementation strategies are proposed: RedSM transmitting redundancy packets as SM traffic and RedGST transmitting redundancy packets as low-priority GST traffic. The performance of the schemes is explored analytically and by simulation. For uniform traffic loads, the RedGST scheme shows the best performance of the two, but even at 60% load the RedSM scheme shows packet loss rates (PLRs)close to 10−5. Simulations with non-uniform traffic loads illustrate the importance of selecting the optimal redundancy ratio; the failure to do so results in up to two orders of magnitude increase in PLR for the RedGST scheme. A much higher tolerance for traffic variations is the main benefit for the RedSM scheme. In view of the results, both schemes are attractive alternatives to buffered contention resolution techniques.

Eliminating Packet Loss Accumulation in Peer-to-Peer Streaming Systems

To eliminate packet loss accumulation and overcome bursty packet loss problems caused by peer departures in peer-to-peer (P2P) streaming systems, a multisource structure combining with a distributed forward error correction (FEC) scheme is proposed. In the proposed structure, each peer connects to multiple parents according to the prespecified FEC packets ensemble and each parent forwards partial streaming packets to the peer. If one or few parents fail, other parents can still provide remaining part of streaming packets that can be used to recover the missing packets by using packet level FEC scheme. Packet loss probability and packet loss accumulation from parent peers to child peers in tree-based P2P streaming systems are investigated. The analysis and NS2 simulation results show that packet loss probability is reduced and furthermore the packet loss accumulation can be eliminated when an appropriate FEC protection is used.

Sub-packet forward error correction mechanism for video streaming over wireless networks

Traditional Forward Error Correction (FEC) mechanisms can be divided into Packet level FEC (PFEC) mechanisms and Byte level FEC (BFEC) mechanisms. The PFEC mechanism of recovering from errors in a source packet requires an entire FEC redundant packet even though the error involves a few bit errors. The recovery capability of the BFEC mechanism is only half of the FEC redundancy. Accordingly, an adaptive Sub-Packet FEC (SPFEC) mechanism is proposed in this paper to improve the quality of video streaming data over wireless networks, simultaneously enhancing the recovery performance and reducing the end-to-end delay jitter. The SPFEC mechanism divides a packet into n sub-packets by means of the concept of a virtual packet. The SPFEC mechanism uses a checksum in each sub-packet to identify the position of the error sub-packet. Simulation experiments show the adaptive SPFEC mechanism achieves high recovery performance and low end-to-end delay jitter. The SPFEC mechanism outperforms traditional FEC mechanism in terms of packet loss rate and video Peak Signal-to-Noise Ratio (PSNR). SPFEC offers an alternative for improved efficiency video streaming that will be of interest to the designers of the next generation environments.

Adaptive two-stage FEC scheme for scalable video transmission over wireless networks

In this paper, we present a two-stage forward error correction (FEC) scheme with an enhanced link-layer protocol especially for multimedia data transmission over wireless LANs. At the application layer, packet-level FEC (stage-one) is added across packets to correct packet losses due to congestion and route disruption. Bit-level FEC (stage-two) is then added to both application packets and stage-one FEC packets to recover bit errors from the link layer. Then at the link layer, header-CRC/FEC is used to enhance protection and to cooperate with the two-stage FEC scheme. The proposed scheme thus provides joint protection across the protocol stack. We explore both its bandwidth efficiency and video performance for the highly efficient and scalable MC-EZBC video codec using the network simulator ns-2. Our results show that the proposed scheme can effectively increase application-layer throughput, reduce both end-to-end transmission delay and application bandwidth fluctuation, and significantly improve video performance.

MAC Layer Multicast Error Control for IPTV in Wireless LANs

Internet Protocol Television (IPTV) over IEEE 802.11 Wireless LANs, which are considered today as the de-facto wireless access network for local distribution (home networks, hotspots), brings forth a big challenge to guarantee high quality multicast/broadcast delivery over unreliable and time-variant wireless channels. However, in IEEE 802.11 Wireless LANs, current standard MAC layer protocols do not provide any error correction scheme for broadcast/multicast. In our previous work, we enhanced a Leader Based Protocol (LBP) and proposed a Beacon-driven Leader Based Protocol (BLBP) for the MAC layer multicast error control. However, as pure Automatic Repeat reQuest (ARQ) schemes, both LBP and BLBP are not efficient for large multicast groups. In this paper, we combine BLBP and packet level Forward Error Correction (FEC) and propose a Hybrid Leader Based Protocol (HLBP) for the MAC layer multicast error control. HLBP transmits the original data packets using raw broadcast and retransmits parity packets using an improved BLBP which is based on block feedback. To guarantee the required Packet Loss Ratio (PLR) under strict delay constraints for multicast delivery over a Gilbert-Elliott (GE) channel, we analyze LBP, BLBP and HLBP, develop analytic performance models that allow optimizing the configurations. The performance models are verified via simulation experiments. Both the theoretical analysis and simulation results show that HLBP is much more efficient than LBP and BLBP especially for large multicast groups and is also more efficient than the best application layer multicast error correction scheme. BLBP needs the minimum number of redundancy transmissions among all pure ARQ based schemes while HLBP needs the near-minimum number of redundancy transmissions among all schemes. Due to the simplicity and efficiency, BLBP is a good choice for IPTV multicast delivery for small groups in Wireless LANs while HLBP is a better choice for large multicast groups.