Bursty Errors Research Articles

Keep the Bursts and Ditch the Interleavers

While many communications media, such as wireless and certain classes of wireline channels, typically lead to bursty errors, most decoders are designed assuming memoryless channels. Consequently, communication systems generally rely on interleaving over tens of thousands of bits to match decoder assumptions. Even for short high rate codes, awaiting sufficient data in interleaving and de-interleaving is a significant source of unwanted latency. We construct an extension to the recently proposed Guessing Random Additive Noise Decoding (GRAND) algorithm, which we call GRAND-MO for GRAND Markov Order. By foregoing interleaving and instead making use of the bursty nature of noise, low-latency communication is possible with block error rates outperforming their interleaved counterparts by a substantial margin. We establish that certain well-known binary codes with structured code-word patterns are ill-suited for use in bursty channels, but Random Linear Codes (RLCs) prove robust to correlated noise. We further demonstrate that by operating directly on modulated symbols rather than de-mapped bits, GRAND-MO achieves further performance and complexity gains by exploiting information that is lost in demodulation. As a result, GRAND-MO provides one potential solution for applications that require ultra-reliable low latency communication.

Embracing Corruption Burstiness: Fast Error Recovery for ZigBee under Wi-Fi Interference

The ZigBee communication can be easily and severely interfered by Wi-Fi traffic. Error recovery, as an important means for ZigBee to survive Wi-Fi interference, has been extensively studied in recent years. The existing works add upfront redundancy to in-packet blocks for recovering a certain number of random corruptions. Therefore, the bursty nature of ZigBee in-packet corruptions under Wi-Fi interference is often considered harmful, since some blocks are full of errors which cannot be recovered and some blocks have no errors but are still requiring redundancy. As a result, they often use interleaving to reshape the bursty errors, before applying complex FEC codes to recover the re-shaped random distributed errors. In this paper, we take a different view that burstiness may be helpful. With burstiness, the in-packet corruptions are often consecutive and the requirement for error recovery is reduced as “recovering any k consecutive errors” instead of “recovering any random k errors”. This lowered requirement allows us to design far more efficient code than the existing FEC codes. Motivated by this implication, we exploit the corruption burstiness to design a simple yet effective error recovery code using XOR operations (called ZiXOR). ZiXOR uses XOR code and the delay is significantly reduced. More, ZiXOR uses RSSI-hinted approach to detect in packet corruptions without CRC, incurring almost no extra transmission overhead. The testbed evaluation results show that ZiXOR outperforms the state-of-the-art works in terms of the throughput (by 47 percent) and latency (by 22 percent).

Error resilient video transmission in ad hoc networks using layered and multiple description coding

The mesh structure of ad hoc networks, provides the possibility of establishing two disjoint paths from a sender to a receiver. Transmission of video over such networks due to their unpredictability and difficulty in securing reliable channels is challenging. Layered Coding (LC) and Multiple Description Coding (MDC) are two different techniques which can benefit from path diversity for robust video communication and also to adapt with preferences of users\network. This paper presents an approach to provide error resilient video transmission over a variety of network conditions and applications needs using combined LC and MDC schemes. In the proposed method two descriptions of each layer are generated in the FMO format of the H.264/AVC standard. Unlike the conventional approaches, in our work macroblocks of each layer are divided into two paths. Hence, in the bursty error conditions the error will be smoothly spread in all layers. For better protection and more network compatibility, the base layer is data partitioned and its important part (DP_A) is repeated in both paths. Simulation results show transmission of duplicated DP_A and the non-corresponding descriptions of two layers together on disjoint paths, can improve the error concealment of the decoder and consequently enhance video quality by up to 2 dB.

Pattern Matching Techniques for Replacing Missing Sections of Audio Streamed across Wireless Networks

Streaming media on the Internet can be unreliable. Services such as audio-on-demand drastically increase the loads on networks; therefore, new, robust, and highly efficient coding algorithms are necessary. One method overlooked to date, which can work alongside existing audio compression schemes, is that which takes into account the semantics and natural repetition of music. Similarity detection within polyphonic audio has presented problematic challenges within the field of music information retrieval. One approach to deal with bursty errors is to use self-similarity to replace missing segments. Many existing systems exist based on packet loss and replacement on a network level, but none attempt repairs of large dropouts of 5 seconds or more. Music exhibits standard structures that can be used as a forward error correction (FEC) mechanism. FEC is an area that addresses the issue of packet loss with the onus of repair placed as much as possible on the listener's device. We have developed a server--client-based framework (SoFI) for automatic detection and replacement of large packet losses on wireless networks when receiving time-dependent streamed audio. Whenever dropouts occur, SoFI swaps audio presented to the listener between a live stream and previous sections of the audio stored locally. Objective and subjective evaluations of SoFI where subjects were presented with other simulated approaches to audio repair together with simulations of replacements including varying lengths of time in the repair give positive results.

On the use of Hidden Markov Processes and auto-regressive filters to incorporate indoor bursty wireless channels into network simulation platforms

In this paper we thoroughly analyze two alternatives to replicate the bursty behavior that characterizes real indoor wireless channels within Network Simulation platforms. First, we study the performance of an improved Hidden Markov Process model, based on a time-wise configuration so as to decouple its operation from any particular traffic pattern. We compare it with the behavior of Bursty Error Model Based on an Auto-Regressive Filter, a previous proposal of ours that emulates the received Signal to Noise Ratio by means of an auto-regressive filter that captures the “memory” assessed in real measurements. We also study the performance of one of the legacy approaches intrinsically offered by most network simulation frameworks. By means of a thorough simulation campaign, we demonstrate that our two models are able to offer a much more realistic behavior, yet maintaining an affordable response in terms of computational complexity.

Adaptive Generative Models for Digital Wireless Channels

Generative models, which can generate bursty error sequences with similar burst error statistics to those of descriptive models, have an immense impact on the wireless communications industry as they can significantly reduce the computational time of simulating wireless communication links. Adaptive generative models aim to produce any error sequences with any given signal- to-noise ratios (SNRs) by using only two reference error sequences obtained from a reference transmission system with two different SNRs. Compared with traditional generative models, this adaptive technique can further considerably reduce the computational load of generating new error sequences as there is no need to simulate the whole reference transmission system again. In this paper, reference error sequences are provided by computer simulations of a long term evolution (LTE) system. Adaptive generative models are developed from three widely used generative models, namely, the simplified Fritchman model (SFM), the Baum-Welch based hidden Markov model (BWHMM), and the deterministic process based generative model (DPBGM). It is demonstrated that the adaptive DPBGM can provide accurate burst error statistics and bit error rate (BER) performance of the LTE system, while the adaptive SFM and adaptive BWHMM fail to do so.

Deterministic process-based generative models for characterizing packet-level bursty error sequences

Errors encountered in digital wireless channels are not independent but rather form bursts or clusters. Error models aim to investigate the statistical properties of bursty error sequences at either packet level or bit level. Packet-level error models are crucial to the design and performance evaluation of high-layer wireless communication protocols. This paper proposes a general design procedure for a packet-level generative model based on a sampled deterministic process with a threshold detector and two parallel mappers. In order to assess the proposed method, target packet error sequences are derived by computer simulations of a coded enhanced general packet radio service system. The target error sequences are compared with the generated error sequences from the deterministic process-based generative model using some widely used burst error statistics, such as error-free run distribution, error-free burst distribution, error burst distribution, error cluster distribution, gap distribution, block error probability distribution, block burst probability distribution, packet error correlation function, normalized covariance function, gap correlation function, and multigap distribution. The deterministic process-based generative model is observed to outperform the widely used Markov models. Copyright © 2013 John Wiley & Sons, Ltd.

Waiting time in block fading MIMO systems with dynamic-depth interleaving

Interleaving is an efficient measure to resolve the bursty errors in a block fading multiple-inputs multiple-outputs (MIMO) system. For the metrics of network layer, interleaving exerts two conflicting effects on the ultimate delay performance. Specifically, interleaving can advantageously reduce data transmit time. On the other hand, it comes at a cost, entailing an undesired delay penalty resulting from interleaving depth. Here, we exploit a unified model to accommodate these two conflicting effects, and derive the average waiting time in block fading MIMO systems with dynamic-depth interleaving. Such a unified model is developed with a combined method of both information theory and queueing theory. Therefore, the model is capable of characterizing the randomness of data arrival process, hence the nature of dynamic-depth interleaving. The methodology and the results are applicable to designing, evaluating, and tuning the practical interleaving systems.

QoS analysis of medium access control in LR-WPANs under bursty error channels

Low Rate Wireless Personal Areas Networks (LR-WPANs) have been widely deployed for the purpose of short range, low rate, and low power wireless networking. The IEEE 802.15.4 standard defines a Medium Access Control (MAC) layer protocol for LR-WPANs. The analytical models reported in the literature for 802.15.4 MAC have been mainly developed under the assumptions of ideal channels or uniform error channels, which fail to capture the characteristics of bursty and correlated channel errors in a practical wireless network environment. In this paper, we present an analytical model for 802.15.4 MAC in LR-WPANs in the presence of bursty error channels. This model can be used to obtain the Quality-of-Service (QoS) performance metrics, including throughput, service time, and frame delay. The accuracy of the model is validated through NS-2 simulation experiments. Utilizing the analytical model, we investigate the QoS performance of 802.15.4 MAC under various traffic loads, backoff parameters, numbers of nodes, and channel conditions. The analytical model is demonstrated to be a cost-effective tool for evaluating the QoS performance of 802.15.4 MAC in the presence of bursty error channels.

A video error resilience redundant slices algorithm and its performance relative to other fixed redundancy schemes

In this paper, a redundant picture formation algorithm that takes into account a given redundancy rate constraint is presented for error resilient wireless video transmission without reliance on retransmissions. The algorithm assigns priorities to macroblocks (MBs) according to two suggested metrics and ranks MBs accordingly. The first metric is based on an end-to-end distortion model and aims at maximising the reduction in distortion per redundancy bit. The end-to-end distortion accounts for the effects of error propagation, mismatch between the primary and redundancy description and error concealment. MBs providing large distortion reduction for fewer bits spent are assigned a higher priority. The second metric employs the variance of the motion vectors of a macroblock and those of its neighbouring blocks. Results show that the rate distortion metric outperforms other examined metrics by up to 2 dB. A comparison with other error resilience schemes, such as loss adaptive-rate distortion optimisation (LA-RDO) and cross packet forward error correction (FEC), is also presented. Results show that our approach outperforms the LA-RDO solution. Cross packet FEC provides better performance in the presence of random packet losses. However, results show that our approach can tackle bursty losses better. With bursty errors, the correction capabilities of the Reed-Solomon codes can be exceeded, and the availability of a coarse representation of the coded macroblocks, through a redundant slice scheme, can offer performance gains of up to 1 dB.

Model of digital and signal channel in the network of Serbian electric power industry

In this paper we use data from extensive measurements, which are implemented in telecommunication networks of electric power industries in the six countries. The model of digital telecommunication channel and the model of hypothetical signaling CCS No7 channel under the influence of bursty errors are presented in the paper. These models can express very accurately data and signaling transmission in the digital telecommunication network (TN) of the Serbian Electric Power Industry (SEPI). We consider the model of digital and signaling channel first and after that analyze the availability of these channels under the influence of bursty errors.

Two-Step Fair Scheduling of Continuous Media Streams over Error-Prone Wireless Channels

In wireless cellular networks, streaming of continuous media (with strict QoS requirements) over wireless links is challenging due to their inherent unreliability characterized by location-dependent, bursty errors. To address this challenge, we present a two-step scheduling algorithm for a base station to provide streaming of continuous media to wireless clients over the error-prone wireless links. The proposed algorithm is capable of minimizing the packet loss rate of individual clients in the presence of error bursts, by transmitting packets in the round-robin manner and also adopting a mechanism for channel prediction and swapping.

Reduced Data Rates for Energy-Efficient Reed–Solomon FEC on Fading Channels

In the CDMA2000 1xEV-DO broadcast service, Reed-Solomon (RS) coding is applied at the medium access control (MAC) layer. Long bursts of errors are corrected by an additional block interleaving mechanism, which improves the performance of RS coding by increasing the time diversity. This is achieved by increasing the width of the error control block (ECB) to convert error bursts into sparse patterns. On the assumption that the number of ECBs transmitted over the air channel in a given interval of time remains constant, we propose performance and energy models of RS decoding under varying conditions of Rayleigh fading on the broadcast channel, which allows for varying levels of block interleaving. Evaluation of this model shows that a higher data rate for the MAC payload and more efficient recovery from bursty errors can be achieved by increasing the level of block interleaving, although it increases the energy consumption. We therefore make the ECB as small as we can without incurring significant performance reduction by sacrificing the data rate to an extent that depends on the channel conditions. We suggest a way of choosing an adequate but energy-efficient level of ECB interleaving and, thus, determine the data rate. Our approach is effective for energy-constrained mobile devices running multimedia applications, which benefit from an increase in energy efficiency, and can tolerate a certain level of packet errors and a reduction in data rate.

Packet-Level FEC Research over Wireless Networks

Over wireless networks, interference caused by external sources, multipath fading due to terrestrial obstruction, and the mobility of transmitters or receivers will result in bursty errors of transmitted packets. To deal with the problem, a packet-level XOR-FEC (forward error control), which improves an FEC scheme what Nachum Shacham and Paul McKenney proposed in an IEEE conference paper in 1990 named Packet recovery in high-speed networks using coding and buffer management, is proposed. The improved scheme, under certain conditions, can recover packets of both corruption and erasure. Because its main operation only involves the use of exclusive-or (XOR), it is low complexity. The scheme has been simulated and can be implemented with software. Simulation experiment results show that the improved scheme could decrease the number of redundant packets, so that the amount of computing to encode and decode can be saved and under certain conditions the XOR-FEC scheme could decrease the PER (packet error rate) without increasing the redundant rate. From the scheme that Nachum Shacham and Paul McKenney proposed, it can be seen that: The scheme does not provide a method to check errors in a packet, so only lost packets can be recovered but corrupted packets can not be corrected Using both row and column parity packets increases the number of redundant packets While receivers gain packets and correct errors in every batch of packets, there is much delay among batches To improve the scheme of Nachum Shacham and Paul McKenney: Using checksum field in every packet to distinguish damaged packets Only add to each column of the array of data packets a parity packet To recover packets in multimedia data transport, a double-window scheme is proposed to decrease the delay among batches of packets and to smooth the jitter among packets in receivers. Experiments show that by adjusting sending windows, under almost the same PER and redundant rate, improved scheme could recover more packets than a packet-level software FEC scheme based on the Reed-Solomon code. Besides, in an experiment, using the improved XOR-FEC, the packet error rate was reduced from about 5.7% to 0.7% and only around 33.3% of redundant packets were injected

Design of coordinator to eliminate redundant local retransmission in wireless networks

Owing to limited bandwidth, high bit error rate, and bursty error in the wireless environment, the performance of the transmission control protocol (TCP) degrades greatly in wireless networks. Up to now, many researchers have contributed greatly to the wireless TCP field. However, in most of their works, the wireless TCP module usually works in the TCP layer and has no idea of the actual time of the packet transmission, which is determined by the Scheduler in the media access control (MAC) layer, and this will bring the inaccuracy to the local retransmission timeout and induce the redundant local retransmission. In this article, a coordinator is introduced into the base-station (BS), which can provide efficient cooperation between the TCP module and the scheduler module. On the bais of the performance analysis and simulation results, the proposed method is shown to eliminate redundant local retransmission, increase throughput, and improve TCP-level fairness in wireless networks. Moreover, this scheme is orthogonal to those existing wireless TCP schemes, thus it can give great compatibility to the current networks, and further enhance the performance of TCP under the condition that the performance improvement benefiting from the existing approaches will not be affected.

Transfer Delay Analysis of WAP 2.0 for Short-Lived Flows

In this paper, an analytical framework for studying the transfer delay of wireless application protocol (WAP) 2.0 for short-lived flows is developed based on a two-state Markov chain that approximates both correlated and independent packet losses. For a given wireless link and protocol parameters, an explicit mathematical expression which yields a good estimate of the WAP 2.0 transfer delay is derived. The analytical results are validated by simulation. It is shown that for large file sizes (> 30 kB), WAP 2.0 is more sensitive to bursty packet losses than random packet losses. It is also shown that the transfer delay of WAP 2.0 can be improved by increasing the size of the initial window in a low-rate bursty error environment but degrades in a high-rate bursty error environment

A synchronous digital hierachy based dynamic error correction technique for wavelength division multiplexing networks

This paper proposes a new synchronous digital hierarchy (SDH) based forward error correction (FEC) scheme for wavelength division multiplexing (WDM) networks. In this scheme, a dedicated WDM channel is used to transport the FEC redundant bits. This paper also proposes the use of error location analysis of the FEC correctable bits to identify the pattern of errors, combined with the seriousness of errors obtained from B2-byte analysis to decide as to the suitable FEC code to be assigned to the payload channels. The proposed FEC scheme is studied not only under the typical Poisson errors but also the bursty errors. Simulation results show that the proposed FEC scheme performs significantly better than the existing FEC schemes. It is also shown that the performance of the proposed FEC scheme on bursty errors is independent of the line rates, whereas the existing FEC schemes either cannot support bursty errors or degrades with line rates.

FEC Performance Analysis Based on Poisson and Bursty Error Patterns for SDH and OTN Systems

This paper analyses and compares the performance of International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) recommended forward error correction (FEC) for the Synchronous digital hierarchy (SDH) system and the newly ratified Optical transport network (OTN) system. The analysis and comparison are based on simulation results using Poisson and bursty error patterns. While a Poisson error pattern is a commonly studied environment for these systems, a bursty error pattern is not. The simulation results show that the FEC for both SDH and OTN support Poisson errors well. However, for bursty errors, it is found that the FEC for SDH does not work well, while the FEC for OTN is working well for short burst length only.

Stabilizing TCP performance over bursty wireless links through the combined use of link-layer techniques

Improving TCP performance over wireless fidelity (WiFi) networks is recognized as a crucial issue, specially in those links prone to suffer from high bit error rate (BER) and bursty error losses. This paper shows how TCP throughput over a real IEEE 802.11b wireless local area network (WLAN) in a lossy office environment is stabilized by a combination of an adaptive forward error correction (FEC) scheme in conjunction with a Snoop agent, both added to the idle repeat request (RQ) mechanism inherently used by such technology. The most innovative aspects of this work are that these techniques operate simultaneously and they have been tested over a real scenario.

Impact of bursty error rates on the performance of wireless local area network (WLAN)

With an increasing popularity of DCF based wireless LAN, the modeling of 802.11 distributed coordination function (DCF) has attracted lots of research attention. Existing analysis of 802.11 DCF has been focused on the determination of the throughput and the packet delay under saturated traffic and ideal channel conditions. Although some recent papers address the saturated performance under a simple uniform error model, they can hardly capture the impact of bursty characteristics of wireless fading on the performance of 802.11 DCF. This paper presents exact formulae for the throughput and the delay in DCF for various traffic conditions when either saturated or unsaturated traffic load is present. A two-state Markov channel model is incorporated to present the bursty characteristics of channel errors. With our analysis, the impact of bursty channel error on unsuccessful transmission probability and the DCF performance can be determined. The results of our analytical framework reveal that the four-way handshaking scheme does not improve throughput substantially for light traffic load. However, for heavy traffic load, the four-way handshaking scheme is advantageous as compared to the basic access scheme. Also, extensive simulation is done to substantiate the accuracy of our analytical model.