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About 2,057 papers for “Automatic repeat request”

Automatic Repeat Request

Thomas E. Fuja · 2003

Abstract This article describes automatic repeat request (ARQ), a technique for improving the reliability of digitally‐transmitted data through the re‐transmission of corrupt frames. It begins by describing the use of cyclic redundancy check (CRC) codes to detect the presence of errors in received data. It then describes three protocols through which the transmitter and receiver coordinate the re‐transmission procedure; those protocols are “Stop‐and‐Wait,” “Go‐Back‐N”, and “Selective Repeat.” These three re‐transmission strategies are briefly analyzed in terms of their efficiency (“throughput”) and reliability (“frame error rate”). Finally, hybrid ARQ schemes, which incorporate both re‐transmission (ARQ) and forward‐error control (FEC) techniques, are discussed.

Cited by 1

Automatic Repeat-Request Courseware

Hu, Hai · Theseus (Ammattikorkeakoulujen) · 2013

An Automatic Repeat Request (ARQ) courseware is demanded from the teacher for the course IIA0502 “Basics of Computer Networks”. A java applet is the target of this design. The user interface must give the user freedom to select necessary parameters, simulate Stop-and-wait, Go-Back-N, Selective Repeat ARQ data transfer process, show the result, allow students have more intuitive understanding of the ARQ theory. 
\nAlthough this ARQ simulation courseware is not perfect running, some bugs are exist, still those simulation results could meet the theory

Cited by 0Open access

Scoped Hybrid Automatic Repeat reQuest . . .

Roger G. Kermode · 2012

Reliable multicast protocols scale only as well as their ability to localize traffic. This is true for repair requests, repairs, and the session traffic that enables receivers to suppress extraneous requests and repairs. We propose a new reliable multicast traffic localization technique called Scoped Hybrid Automatic Repeat

Cited by 0

New Protocols: Automatic Repeat reQuest

Rajatsubhra Goswami, Swarnendu Kumar Chakraborty · 2017

Transmission of error free packet from source to destination is a research challenge. Packet Combining (PC) / Packet merging scheme is a simple & elegant technique in error correction. Packet combining has been elaborately studied by many researchers elsewhere: Several variations of PC aimed for higher throughput, better efficiency & higher reliability are studied in literature: Aggressive Packet Combining scheme introduced by Leung is a logical & legitimate extension of PC for application to the mobile & wireless network. APC considered & studied by Leung has found to have several limitations including low throughput & failure to correct error in several cases of error syndrome in packets. Basic aim of APC is to combat error with lower delay. In meeting the basic objective of APC, several modifications of APC were suggested by Bhunia, in this to achieve higher throughput, better reliability, also we attempt to make literature survey of various modified APC, these modifications are MPC (Majority Packet Combining Scheme), PRPC (Packet Reversed Packet Combining Scheme) and Error forecasting PC. Based on survey & research, some new methods & new directions are proposed & studied.

Cited by 0

Automatic repeat request on fading channels

Beirouti, Patrick · eScholarship@McGill (McGill) · 1992

Automatic repeat request (ARQ) is a widespread technique for error control in data communication systems.This research examines the performance of conventional ARQ schemes over fading channels.The basic Gilbert-Elliott two-state Markov mode! is used to represent these channels.This basic model is recursively extended to a 2"-state Markov chain suitable for n-bit block codes.Using this 'Extended Gilbert-EllioU' model, an approximation of the throughput efficiency of the conventional ARQ schemes is derived.This approximation is particularly valid for slow fading channels.Furthermore, performance plots are obtained, showing the effects of channel fading on throughput efficiency: ARQ performance deteriorates with slower fading, or alternatively, higher channel memory.Consequently, frequency-hopped codeword transmission is explored, a technique by which channel memory can be reduced.Throughput performance of frequency-hopped ARQ systems is derived, which shows significant potential improvements over systems with no frequency hopping.IV

Cited by 0Open access

Automatic repeat request assisted cordless telephony

Lajos Hanzo, Richard Lucas, Jason Woodard · 2002

A generic re-transmission scheme is proposed for packet reservation multiple access (PRMA) assisted indoors cordless voice communications. Its frame error rate (FER) versus channel signal-to-noise ratio (SNR) performance is assessed under various traffic loading conditions using the example of a re-configurable transceiver. A significant operating SNR reduction can be achieved, if the traffic load is not excessive. This effect is particularly pronounced, if the speech transceiver used can drop its transmission rate and accommodate this lower rate using a more robust modem, when attempting re-transmission. The key system features are summarised.

Cited by 0

Automatic-repeat-request protocols for data communication networks

Yet Keung Chang · Open Collections · 2010

The performances of a number of Automatic-Repeat-Request (ARQ) protocols are compared on the basis of the expected wasted time per message incurred over random-error and Rayleigh fading channels. These include the standard Stop-And-Wait, Go-Back-N, and Selective-Repeat schemes. The reductions in expected wasted times achievable through the use of forward-error-correction (FEC) are demonstrated. It is found that in general, substantial improvements in performance can be obtained by using FEC. A new ARQ protocol proposed by Weldon is studied. It is shown that the throughput of Weldon's scheme can be increased by allowing multiple copies of a new data block to be sent. In order to maximize the throughput in Weldon's scheme, a number of parameters need to be selected optimally. An efficient method for choosing these parameters is obtained by exploiting the structure of a simplified expression for the throughput. The problem of the optimal block length that minimizes the expected wasted time per message is also considered. An exact analysis of the optimal block length is developed for the Stop-And-Wait scheme using an end-of-message character in the last block of a message. The optimal block length is a function of average message length, channel error rate, overhead per packet, acknowledgement delay and transmission rate. It is found that the optimal block length converges to a constant value when the average message length becomes large. Finally, the performance of an algorithm that computes the optimal block length in an adaptive way is examined.

Cited by 0Open access

Time Diversity Automatic Repeat Request (ARQ) Equalization Scheme

F. Blackmon · Defense Technical Information Center (DTIC) · 2004

A method and system are provided for processing communication signals. In one embodiment, the method has the steps of providing a data signal based on a communication signal transmitted from a transmitting source, processing the data signal to determine if the data signal has acceptable error characteristics, requesting retransmission of the data signal if the data signal does not have acceptable error characteristics, coherently and jointly equalizing the data signal and the retransmitted signal to produce an equalized signal, decoding the equalized signal to provide an equalized and decoded signal, processing the equalized and decoded signal to determine if the equalized and decoded signal has acceptable error characteristics, and repeating the requesting, equalizing, decoding and processing steps as long as the equalized and decoded signal has unacceptable error characteristics.

Cited by 0

Superposition Aided Delay-Constrained Hybrid Automatic Repeat reQuest

L. Hanzo, Rong Zhang, Lajos Hanzo · 2016

Abstract — A novel Multiplexed Hybrid Automatic Repeat reQuest (M-HARQ) scheme is proposed and compared to the conventional scheme in terms of its energy efficiency, while satisfying specific delay constraints, where the best transmission strategy is discussed for both schemes. By employing the proposed scheme, the transmission rate and power can be reduced, while maintaining the maximum energy efficiency and meeting specific delay constraints. Alternatively, the cell-radius distance may be extended by about 10%, which results in a coverage area extension by a factor of 1.21. I.

Cited by 0

Analysis of Feedback Error in Automatic Repeat reQuest

Saeed R. Khosravirad, Harish Viswanathan · arXiv (Cornell University) · 2017

The future wireless networks envision ultra-reliable communication with efficient use of the limited wireless channel resources. Closed-loop repetition protocols where retransmission of a packet is enabled using a feedback channel has been adopted since early days of wireless telecommunication. Protocols such as automatic repeat request (ARQ) are used in today's wireless technologies as a mean to provide the link with reduced rate of packet outage and increased average throughput. The performance of such protocols is strongly dependent to the feedback channel reliability. This paper studies the problem of feedback error and proposes a new method of acknowledging packet delivery for retransmission protocols in unreliable feedback channel conditions. The proposed method is based on backwards composite acknowledgment from multiple packets in a retransmission protocol and provides the scheduler of the wireless channel with additional parameters to configure ultra-reliable communication for a user depending on channel quality. Numerical analysis are presented which show orders of magnitude increase in reliability of the proposed method as compared to ARQ at the cost of a small increase in average experienced delay.

Cited by 12Open access

Automatic repeat request schemes for infrared wireless communications

V. Vitsas, Anthony C. Boucouvalas · Electronics Letters · 2002

The effectiveness of employing a stop-and-wait automatic repeat request protocol as well as a go-back-N protocol to cope with transmission errors in infrared wireless connections is examined. Protocol performance for various link parameters, such as window size, packet size and timer time-out values is presented. High window size implementation results in better performance.

Cited by 5

Networked Control with Hybrid Automatic Repeat Request Protocols

Touraj Soleymani, John S. Baras, Denız Gündüz · 2024

We study feedback control of a dynamical process over a lossy channel equipped with a hybrid automatic repeat request protocol that connects a sensor to an actuator. The dynamical process is modeled by a Gauss-Markov process, and the lossy channel by a packet-erasure channel with ideal feedback. We suppose that data is communicated in the format of packets with negligible quantization error. In such a networked control system, whenever a packet loss occurs, there exists a tradeoff between transmitting new sensory information with a lower success probability and retransmitting previously failed sensory information with a higher success probability. In essence, an inherent tradeoff between freshness and reliability. To address this tradeoff, we consider a linear-quadratic-regulator performance index, which penalizes state deviations and control efforts over a finite horizon, and jointly design optimal policies for an encoder and a decoder, which are collocated with the sensor and the actuator, respectively. Our emphasis here lies specifically on designing switching and control policies, rather than error-correcting codes. We derive the structural properties of the optimal encoding and decoding policies. We show that the former is a threshold switching policy and the latter is a certainty-equivalent control policy. In addition, we specify the iterative equations that the encoder and the decoder need to solve in order to implement the optimal policies.

Cited by 1

Hybrid Automatic Repeat Request Scheme With Turbo Codes

Jozef Hamorsky, Udo Wachsmann, Johannes B. Huber et al. · 2007

A novel hybrid automatic repeat request system based on turbo codes, called turbo HARQ system, is proposed. The iterative turbo decoding procedure is exploited to request retransmission of not decodable blocks without the necessity of an outer error--detecting code. It is shown that the turbo HARQ scheme with code rate R c = 1=2 and interleaver length 1024 significantly outperforms the classical turbo coding scheme --- especially for low SNR --- without essential loss in throughput. 1 INTRODUCTION Automatic repeat request (ARQ) protocols are well--known methods to achieve high reliability in digital transmission schemes. The information is protected by an error--detecting block code. If the decoder detects an erroneous transmitted block, retransmission of this block is requested via a feedback channel which is assumed to be error--free throughout this paper. Additionally, the request is assumed to be repeated until the decoder detects error--free transmission. The great advantage of s...

Cited by 0

Majority decoded automatic repeat request error control schemes

Li, VOK, Wu, CS · The HKU Scholars Hub (University of Hong Kong) · 2012

The authors propose a simple method to improve the performance of automatic repeat request (ARQ) error control. To minimize the hardware and software overhead they do not use a sophisticated coding method. Instead, when a transmission error occurs, the erroneous packet, instead of being discarded as in traditional ARQ, is kept for majority decoding later. The authors apply the method to various ARQs, including ideal selective-repeat and go-back-N under point-to-point and point-to-multipoint communication environments. They also study the effect of transmitting multiple copies of a packet. The analysis shows that higher throughput is obtained when bit error rate is high or when the number of receivers is large.

Cited by 0