Evaluating Forward Error Correction performance in BitTorrent protocol

The performance of forward error correction (FEC) based on Reed-Solomon coding is analyzed experimentally for a burst-mode upstream channel within a passive optical network (PON) testbed. During this analysis, the upstream FEC performance is impaired by inducing correlated and localized errors within the burst through the injection of optical transients. These transients emulate the optical signal variation associated with the add-and-drop events of wavelength channels within a long-reach optical link based on a chain of erbium doped fiber amplifiers (EDFAs). The robustness of the FEC has been analyzed by measuring the post-FEC bit error rate (BER) as a function of the amplitude of the emulated transients and their delay with respect to the transmitted bursts. A margin of approximately 4dB is demonstrated for the transient amplitude before the FEC degradation. Furthermore, while the post-FEC BER is strongly degraded by the emulated transients, the pre-FEC BER stays below the FEC threshold, demonstrating the importance of measuring the post-FEC BER in order to correctly characterize the FEC performance in PON upstream channels affected by optical transients.

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.

Cell rate moderation of VBR video under an FEC environment in ATM networks

In this paper we evaluate the performance of forward error correction (FEC) techniques in the presence of four wave mixing (FWM) and dispersion induced inter-symbol interference (ISI). A comparison with the detuning technique [1] is also presented, for the case of FWM penalty mitigation. FEC has been widely used in long haul submarine optical transmission systems, both repeated [2] and unrepeated [3] and its performance in the presence of polarization mode dispersion (PMD) has also been investigated [4,5]. The influence of non-linearities on optical systems that use FEC has recently been reported [6].

Digital Video Broadcasting-Terrestrial second generation (DVB-T2) systems are increasingly deployed for high quality terrestrial broadcasting. However, low Signal-to-Noise Ratio (SNR) conditions in urban and fringe coverage areas pose significant challenges, resulting in elevated Bit Error Rates (BER) and degraded service reliability. Forward Error Correction (FEC) techniques, particularly Low-Density Parity-Check (LDPC) and Bose Chaudhuri Hocquenghem (BCH) codes, play a crucial role in mitigating transmission errors and ensuring robust communication. This study investigates a systematic approach to optimizing LDPC and BCH FEC schemes to enhance transmission reliability and minimize BER under low-SNR conditions in DVB-T2 networks. Using simulation-based analyses, the study evaluates multiple LDPC code rates (e.g., 1/2, 2/3, 3/4) in combination with BCH codeword lengths and error-correcting capabilities. Results indicate that an optimized LDPC (64800, 32400) configuration combined with a BCH (255, 239) code significantly reduces BER, achieving approximately 10⁻⁵ at an SNR of 2 dB, compared to a BER of 10⁻³ using standard DVB-T2 FEC configurations. Additionally, iterative decoding algorithms for LDPC were fine-tuned to balance convergence speed and error correction performance, demonstrating a 25% reduction in decoding iterations without compromising reliability. The analysis also explores trade-offs between redundancy, throughput and latency, highlighting the practical considerations for real-world deployment. The findings underscore that strategic optimization of LDPC/BCH FEC parameters is critical for maintaining broadcast quality in low-SNR scenarios. By enhancing error resilience and reducing BER, the proposed approach improves signal integrity, supports consistent reception in fringe areas and maximizes spectrum efficiency. This work provides a foundation for adaptive FEC strategies in future DVB T2 systems, enabling broadcasters to deliver reliable high-definition content even under challenging channel conditions.

In order to improve the data transmission reliability of mobile ad hoc network, a routing scheme called integrated forward error correction multipath routing protocol was proposed, which integrates the techniques of packet fragmenting and forward error correction encoding into multipath routing. The scheme works as follows: adding a certain redundancy into the original packets; fragmenting the resulting packets into exclusive blocks of the same size; encoding with the forward error correction technique, and then sending them to the destination node. When the receiving end receives a certain amount of information blocks, the original information will be recovered even with partial loss. The performance of the scheme was evaluated using OPNET modeler. The experimental results show that with the method the average transmission delay is decreased by 20% and the transmission reliability is increased by 30%.

Due to the complex downhole environment in oil and gas wells, electromagnetic wave wireless transmission suffers from high attenuation, multipath interference, and low signal-to-noise ratio, making long-distance and reliable communication difficult. To address these challenges, a composite modulation method combining Differential Phase Shift Keying (DPSK) and Forward Error Correction (FEC) is proposed. A downhole channel model incorporating path loss, multipath effects, and noise interference was established, and a transmitting–receiving hardware system was designed. Signal transmission characteristics in different media were experimentally investigated to analyze electromagnetic signal propagation behavior. The encoding and decoding performance of the DPSK–FEC scheme was evaluated through MATLAB simulations, focusing on the phase disturbance resistance of DPSK and the error correction capability of FEC. The coding parameters were further optimized to match downhole channel characteristics. The non-coherent demodulation mechanism of DPSK provides robustness against phase noise and frequency drift, while FEC introduces redundancy to detect and correct transmission errors, significantly improving system reliability. Experimental results show that the proposed system can operate stably at a depth of 1000 m and an environmental temperature of 75°C, enabling reliable bidirectional transmission of downhole data over long distances.

Forward error correction (FEC) technique has been widely used in wireless communication and mass storage applications. In recent years, FEC has also become very important to optical communication because of its powerful error correcting ability. FEC codes provide performance gain by trading off coding gain with coding redundancy and decoding complexity. For transmission bit rate of 10 Gb/s or higher, coding redundancy of less than 25% is desired. Therefore, FEC schemes with moderate coding redundancy and tolerable decoding complexity are desirable and very important for high-speed long-haul optical systems. In this thesis, two FEC augmentation schemes, namely wavelength interleaving and errors-and-erasures decoding (E&ED), are proposed to improve the FEC performance of optical channels subjected to polarization mode dispersion (PMD) and chromatic dispersion (CD). Wavelength interleaving provides frequency diversity, hence reducing the effective error burst length and improving FEC performance without requiring more coding redundancy. In E&ED scheme, an erasure zone is used to collect highly unreliable received symbols called erasure symbols.

In this paper, we study two problems of providing reliable data transmission and developing aggregation techniques for correlated data in wireless sensor networks. A system with forward error correction (FEC) can provide an objective reliability while using less transmission power than a system without FEC. Because of the additional parity bits and encoding/decoding energy consumptions, we study the effect of FEC on energy efficiency. We propose to use LDPC codes for FEC. We show that wireless sensor networks using LDPC codes are almost 45% more energy efficient than those that use BCH codes, which were shown to be 15% more energy efficient than the best performing convolutional codes. Then we study the problem of providing aggregation for two and three correlated nodes in wireless sensor networks. We propose to use LDPC codes in wireless sensor networks for source and channel coding to obtain a two-fold energy savings. For two correlated nodes, we study both distributed source coding and joint source-channel coding. While distributed source coding using LDPC codes was studied before, joint source-channel coding using LDPC codes is introduced for the first time. The difference between our work in distributed source coding using LDPC codes and the previous work lies in the LDPC code design procedure. The simulation results show that our proposed design criteria improves the performance of the source coding. The convergence of the non-uniform LDPC code of our design technique is almost 60% closer to the Slepian-Wolf limit. For three correlated nodes, we study distributed source coding using LDPC codes. We simplified the problem of design procedure to randomly punctured LDPC codes. This is a new approach for designing LDPC codes and the simulation results for code of length 1000 shows that the convergence of the LDPC code is achieved at compression rate 0.3174 which is only 0.08 away from the Slepian-Wolf limit.

Currently, grid computing and CD/DVD delivery are considered as applications in OBS networks. For these applications, multiple bursts are required to be transmitted simultaneously to any node in contrast with the conventional burst transmission. Moreover, the reliable transmission has to be provided for the multiple bursts. In this paper, we propose a consecutive burst transmission with burst loss recovery based on forward error correction (FEC) for the multiple-bursts transmission. In the proposed method, redundant data is generated from multiple bursts with FEC, and a redundant burst is assembled with the redundant data. Then, the multiple bursts and the redundant burst are transmitted consecutively. If a burst among the bursts is lost at some intermediate node, the lost burst is recovered with the redundant burst at the destination. We evaluate by simulation the proposed method in a uni-directional ring network and compare the performance of the proposed method with the extra-offset time scheme. Numerical examples show that the proposed method can provide a more reliable transmission than the extra-offset time scheme for the OBS network where the burst size and the maximum number of hops are large.

For wireless multicast applications like multimedia conferencing, voice over IP and video/audio streaming, a reliable transmission of packets within short delivery delay is needed. Moreover, reliability is crucial to the performance of error intolerant applications like file transfer, distributed computing, chat and whiteboard sharing. Forward Error Correction (FEC) is frequently used in wireless multicast to enhance Packet Error Rate (PER) performance, but cannot assure full reliability unless coupled with Automatic Repeat Request forming what is knows as Hybrid-ARQ. While reliable FEC can be deployed at different levels of the protocol stack, it cannot be deployed on the MAC layer of the unreliable IEEE802.11 WLAN due to its inability to exchange ACKs with multiple recipients. In this paper, we propose a Multicast MAC protocol that enhances WLAN reliability by using Adaptive FEC and study it's performance through mathematical analysis and simulation. Our results show that our protocol can deliver high reliability and throughput performance.

In this paper we propose a transport connection model managed by reliable transport protocol with forward error correction (FEC) in the modes of selective and group reject in the form of a discrete-time Markov chain. It takes into account the influence on the transport connection throughput by protocol parameters (window size and acknowledge time-out duration), error level in the communication channels of the data transmission path, round-trip delay, and forward error correction process parameters. We assessed the benefits of the transport protocol with FEC over the classic transport protocol in the multidimensional feature space of influencing variable values.

In real-time video streaming, data packets are transported over the network from a transmitter to a receiver. The quality of the received video fluctuates as the network conditions change, and it can degrade substantially when there is considerable packet loss. Forward error correction (FEC) techniques can be used to recover lost packets by incorporating redundant data. Conventional FEC schemes do not work well when scalable video coding (SVC) is adopted. In this paper, we propose a novel FEC scheme that overcomes the drawbacks of these schemes by considering the reference picture structure of SVC and weighting the reference pictures more when FEC redundancy is applied. The experimental results show that the proposed FEC scheme outperforms conventional FEC schemes.

Forward error correction (FEC) based on Reed–Solomon coding for the burst-mode upstream traffic of passive optical networks (PONs) is analyzed in detail using flexible field-programmable gate arrays (FPGAs). In order to achieve true burst-mode transmission using FPGAs, specific architectural solutions are required. In particular, a burst-mode frame synchronizer and a burstmode Reed–Solomon decoder are described in detail and analyzed experimentally within a state-of-the-art longreach PON test-bed. During this analysis, the upstream FEC performance is impaired by introducing strongly correlated and localized errors within the burst through the reduction of the burst preamble duration. The observed FEC degradation is exhaustively analyzed by implementing on the FPGAs a tool for error location analysis and frame loss measurements. This investigation demonstrates the importance of understanding the error distribution within the burst in order to correctly estimate the FEC performance in PON upstream links.

The transmission of video traffic over the Internet is a fundamental issue of network design. Video applications require quality of service guarantees from the network in terms of limited packet loss, end-to-end delay, and delay variation. The question of today’s research and development is how to provide these guarantees considering the architecture of the present Internet. In the last years a variety of admission control schemes based on per-hop or end-to-end measurements has been suggested to control delay and loss sensitive streams with very little or no support at the routers. Most of these solutions, however, have to apply the same acceptance threshold for all streams, a significant limitation considering the diverse quality requirements of the applications. In this work we investigate how source shaping and forward error correction (FEC) can be used together to achieve application specific quality differentiation in terms of end-to-end delay and packet loss probability. While source shaping and FEC have been proposed independently to decrease the probability of packet loss due to buffer overflow, their joint use has not been studied before.As the two control functions use the same scarce resource, end-node delay, and their efficiency to decrease loss probability is proportional to the introduced delay but with a decreasing marginal gain, combining the two a better performance can be achieved than by using only one of them.The performance evaluation focuses on the optimal delay allocation for shaping and FEC, such that the loss probability is minimized. We investigate how shaping can be used to substitute FEC redundancy and the sensitivity of the quality differentiation to the background traffic characteristics.KeywordsQuality of Servicesource shapingFEC