Adaptive Automatic Repeat Request Research Articles

Adaptive Automatic Repeat Request (AdARQ) Protocol to Improve the Throughput Characteristic of the Time-Varying Wireless Channel

Adaptive Automatic Repeat Request (AdARQ) Protocol to Improve the Throughput Characteristic of the Time-Varying Wireless Channel

Multi-sector discrete-time channel model for data link layer evaluation of CubeSat communications

Innovation in the space sector is going through a fruitful period. Among other factors, this has been a consequence of the CubeSat paradigm and its acceptance in the educational, scientific, and commercial sectors, as well as its relevant role in the integration of terrestrial and satellite communication systems. Nevertheless, there is no standardized communication protocol for CubeSat technology. One of the reasons for this lack of standardization is the nonexistence of a widely accepted communication channel model for fast development and simulation of CubeSat technology at the data link layer level. Aiming at filling this gap, we propose a communication channel model that captures both the dynamics of the CubeSat in the low earth orbit and the propagation environment where the terrestrial devices are located, taking into account the elevation angle. For this purpose, finite state Markov chains are used to model the time evolution of the channel fading through the satellite trajectory when it passes by the ground point target. Then, CCSDS recommendations are used as a study case for the data link layer of a CubeSat, while an adaptive automatic repeat request mechanism, according to the elevation angle, is simulated and optimized, showing the usefulness of the proposed channel model.

Erasure coding for reliable adaptive retransmission in wireless broadcast/multicast systems

In this paper, we present new adaptive automatic repeat request (ARQ) schemes for wireless broadcast/multicast combining erasure coding (EC) and packet retransmission. Traditional approaches rely on retransmitting the lost packets in a point-to-point or point-to-multipoint mode. The main idea behind the presented protocols is to retransmit adaptive combinations of the lost packets using EC, which can help several receivers to recover the lost information with fewer retransmission attempts. We propose two versions of EC-based ARQ protocols, and investigate theoretically the corresponding transmission bandwidths in different contexts. We show through simulation results the efficiency of the proposed protocols with respect to conventional ARQ strategies and new published ARQ works for broadcast/multicast. Finally, a new sliding window NACK feedback policy is presented for the case of a high number of receivers to avoid the feedback implosion problem.

Joint-Design of Link-Adaptive Modulation and Coding with Adaptive ARQ for Cooperative Amplify and Forward Relaying System

This paper analyzes the efficiency of a joint-design of an adaptive modulation and coding (AMC) at the physical (PHY) layer with an adaptive R max -truncated selective-repeat automatic repeat request (ARQ) protocol at the medium access control (MAC) layer to maximize the throughput of cooperative nonregenerative relay networks under prescribed delay and/or error performance constraints. Particularly, we generalize the existing design model/results for cross-layer combining of AMC along with truncated ARQ in non-cooperative diversity networks in three-folds: (i) extension of the cross-layer PHY/MAC design or optimization to cooperative diversity systems; (ii) generalization/unification of analytical expressions for various network performance metrics to generalized block fading channels with independent but nonidentically distributed (i.n.d) fading statistics among the spatially distributed nodes; (iii) analysis of the effectiveness of joint-adaptation of the maximum retransmission limit R max of ARQ protocol and cooperative diversity order N for delay-insensitive applications. Our insightful numerical results reveal that the average throughput can be increased significantly by judiciously combining two additional degrees of freedom (N and R max ) that are available in cooperative amplify-and-forward (CAF) relay networks besides employing AMC at the PHY layer, especially in the most challenging low signal-to-noise ratio (SNR) regime.

Analysis of Optimal Spectral Efficiency with Adaptive Modulation Coding and Cooperative ARQ Protocols

In this paper aiming at maximizing the spectral efficiency, a cross-layer design which combines adaptive modulation and coding (AMC) at the physical layer and truncated automatic repeat request (ARQ) protocol at the data link layer in cooperation system is proposed. In order to analyze the system performance, we first derive a closed form expression of probability density function (PDF) of the received signal-to-noise (SNR) using maximum ratio combing (MRC) at the destination node, the theoretical results and simulation show that the new design outperforms the traditional AMC system especially at low SNR.

GM (1,1) model based on adaptive link-level ARQ mechanism for wireless media streaming

In this paper,an adaptive link-level Automatic Repeat reQuest(ARQ) algorithm was proposed for wireless media streaming,in the hope that the media could be played on receivers with high quality.The algorithm,based on cross-layer optimization design,predicts the packet loss rate using the model of GM(1,1),and adjusts the ARQ parameter Nmax according to the characteristics of the number of frames of a GOP.Besides,an adaptive FEC at the application layer was used to adjust the sending rate of MPEG video frame adaptively and to allocate the network bandwidth resource between the MPEG video source data and the redundant data dynamically.Both the mathematical analysis and NS simulation results demonstrate that the proposed mechanism can significantly improve quality of media streaming,in terms of playable frame rate,reliability and real-time performance on the receiving side.

Fuzzy Logic Control of Adaptive ARQ for Video Distribution over a Bluetooth Wireless Link

Bluetooth's default automatic repeat request (ARQ) scheme is not suited to video distribution resulting in missed display and decoded deadlines. Adaptive ARQ with active discard of expired packets from the send buffer is an alternative approach. However, even with the addition of cross-layer adaptation to picture-type packet importance, ARQ is not ideal in conditions of a deteriorating RF channel. The paper presents fuzzy logic control of ARQ, based on send buffer fullness and the head-of-line packet's deadline. The advantage of the fuzzy logic approach, which also scales its output according to picture type importance, is that the impact of delay can be directly introduced to the model, causing retransmissions to be reduced compared to all other schemes. The scheme considers both the delay constraints of the video stream and at the same time avoids send buffer overflow. Tests explore a variety of Bluetooth send buffer sizes and channel conditions. For adverse channel conditions and buffer size, the tests show an improvement of at least 4 dB in video quality compared to nonfuzzy schemes. The scheme can be applied to any codec with I-, P-, and (possibly) B-slices by inspection of packet headers without the need for encoder intervention.

Evaluation of rate compatible block turbo codes for multimedia application in satellite communication network

AbstractIn this paper, we evaluate the performance of the hybrid automatic repeat request (ARQ) scheme combined with adaptive coding in satellite communication systems. A cross‐layer design which combines the ARQ scheme in the data link layer and adaptive coding and modulation in the physical layer is very important to maximize system throughput and/or performance. Due to the long round trip delay in satellite systems, the strategy to adopt may need to be different from that is used in the terrestrial systems. A rate compatible code is a desirable scheme for adaptive coding and hybrid ARQ. In this paper, we propose an adaptive coding scheme with hybrid ARQ using rate compatible block turbo codes, and demonstrate its performance on a mobile satellite channel for multimedia applications. The proposed rate compatible block turbo codes are a very effective tool to improve the performance of satellite systems using adaptive coding with hybrid ARQ. The simulation results presented in this paper reveal that the hybrid ARQ scheme combined with adaptive coding can improve the system performance by effectively compensating for the various channel attenuations. Copyright © 2006 John Wiley & Sons, Ltd.

SR ARQ for Adaptive Modulation Systems Combined With Selection Transmit Diversity

Adaptive automatic repeat request (ARQ) schemes are quite effective for throughput enhancement in time-varying mobile channel environments. In this paper, both throughput and packet error rate are analyzed for a selective-repeat ARQ scheme based on a constant-power variable-rate adaptive M-QAM system combined with selection transmit diversity over multiple-input multiple-output Markovian-Nakagami channels. In this analysis, the impact of using outdated and/or imperfect channel state information on the performance of the system is considered.

Cross-layer QoS Support for Multimedia Delivery over Wireless Internet

Delivering multimedia over wireless Internet is a very challenging task. Multimedia delivery inherently has strict quality of service (QoS) requirement on bandwidth, delay, and delay jitter. However, the current Internet can only support best-effort service, which imposes varying network conditions during multimedia delivery. The advent of wireless networks further exacerbates the variance of network conditions and brings greater challenges for multimedia delivery. To improve perceived media quality by end users over wireless Internet, QoS supports can be addressed in different layers, including application layer, transport layer, link layer, and so forth. This paper presents a framework, which provides QoS support, for multimedia delivery over wireless Internet, across different layers. To provide efficient QoS support for different types of media over the best-effort networks, we first propose a cross-layer architecture, which combines the application-level, transport-layer, as well as link-layer controls, and then review recent advances in each individual component. Specifically, dynamic estimation of varying channel and network, adaptive and energy-efficient application and link-level error control, efficient congestion control, header compression, adaptive automatic repeat request (ARQ) and priority-based scheduling, as well as QoS-adaptive proxy caching technologies are explicitly reviewed in this paper.

On ARQ scheme with adaptive error control

Adaptive automatic repeat request (ARQ) schemes are quite effective for throughput enhancement in time-varying mobile channel environments. An ARQ scheme with adaptive error-correcting codes is considered. A robust channel sensing algorithm by making use of XOR-ing is proposed for link adaptation. With the proposed channel estimation algorithm, an adaptive scheme that adapts its error-correcting codes according to channel conditions is presented. The efficiency of the proposed adaptive ARQ scheme is evaluated in terms of throughput performance by computer simulation for a time-varying mobile channel characterized by Rayleigh fading and log-normal shadowing. As an enhancement in counteracting long deep fades, the incorporation of frequency diversity into an adaptive ARQ scheme is also investigated and the simulation results show that this scheme is quite efficient in counteracting long deep fades.

An Efficient ARQ Protocol for Adaptive Error Control over Time-Varying Channels

This paper investigates a simple and efficient stop-and-wait (SW) automatic repeat-request (ARQ) scheme with adaptive error control. In this scheme, the channel state information (CSI) is extracted by monitoring the contiguous positive acknowledgment (ACK) or negative acknowledgment (NAK) messages. Exploiting this CSI, we adapt the coding strategy to the changes in the channel condition, and thus improve the throughput efficiency. In order to facilitate the throughput analysis and parameters optimization, we model the adaptive system with a Markov chain. Using this analytical model and assuming a static channel, an exact throughput expression for the adaptive ARQ protocol is derived and suboptimal adaptive system parameters are obtained. These design parameters are applied to the adaptive system in a typical time-varying mobile radio channel characterized by Rayleigh multipath fading on top of lognormal shadowing. The throughput performance of the proposed adaptive SW-ARQ scheme in such a time-varying fading channel is evaluated by computer simulation. For slow fading channels, the proposed adaptive system can track the channel variations very well, hence much throughput improvement can be achieved over conventional nonadaptive SW-ARQ schemes for almost all SNR values considered. The simulation results also confirm the applicability of the adaptive system parameters, so-obtained by the throughput analysis in static channel, to a time-varying mobile radio channel.

Analysis and optimization of adaptive multicopy transmission ARQ protocols for time-varying channels

This paper outlines an efficient method to concurrently optimize a multiplicity of design variables for continuous selective-repeat (SR) and go-back-N (GBN) automatic repeat request (ARQ) strategies, both in noiseless and noisy feedback channels. For these ARQ protocols, we adapt either the number of identical message blocks sent in each transmission (in the case of GBN scheme) or the number of copies of a block retransmitted to handle a NACKed codeword (for the SR protocol) dynamically to the estimated channel condition. The channel state information is obtained by counting the contiguous acknowledgment (ACK or NACK) messages. Exploiting the asymptotic properties of the steady state probability expressions, we show analytically that the optimum solution indeed lies in the infinite space. Subsequently, a simple expression to estimate the suboptimal design parameters is suggested. Our approach of minimizing the mean-square error function yields to a quantitative study of the appropriateness of the selected parameters. Exact analytical expressions that allows us to compute the throughput crossover probability between any two arbitrary multicopy transmission modes are derived. The results provide fundamental insights into how these key parameters interact and determine the system performance.

On adaptive go-back-N ARQ protocol for variable-error rate channels

This letter presents a simple method to simultaneously optimize a multiplicity of design parameters for the adaptive automatic repeat request strategy previously reported, and subsequently provides a quantitative measurement that reflects the appropriateness of the selected parameters. An exact analytical expression that allows us to compute the throughput crossover probability between the two different protocols is derived. The results provide fundamental insights into how these key parameters interact and determine the system performance.

Adaptive type-II hybrid broadcast ARQ system

In this letter, a type-II hybrid broadcast automatic-repeat-request (ARQ) scheme with adaptive forward error correction (AFEC) using BCH codes is proposed and analyzed. The basic idea in the proposed scheme is to increase the error correcting capability of BCH codes according to each channel state using incremental redundancy. The numerical results for the analysis and the simulation show that the proposed scheme maintains high throughput even if channels become noisy and the number of receivers is large.

Optimal adaptive multireceiver ARQ protocols

The authors study data link error control protocols suitable for point-to-multipoint communication where data are delivered to the destinations in the order they are sent. They study a series of adaptive protocols differing in the way that the sender uses the outcomes of the previous transmissions. The protocols are based on the go-back-N schemes discussed by I.S. Gopal and J.M. Jaffe (1984), whose protocols are generalized to the case where multiple copies of a message are sent (instead of just a single copy). The optimum number of copies is determined and is found to depend on how many receivers have not yet received the message. These adaptive protocols can be applied to all three basic ARQ (automatic repeat request) schemes, namely, stop-and-wait, go-back-N, and selective-repeat. A dynamic programming technique is used to solve this optimization problem. A throughput comparison shows that, by sending the optimum number of copies of a data frame instead of just a single copy, the performance will be significantly improved. >

Adaptive stop-and-wait ARQ strategy for mobile data communications

Automatic Repeat reQuest (ARQ) techniques are often used by packet switching data communication networks to provide an error-free communications link between stations. The ARQ technique ensures consistent data quality under varying link conditions. Unfortunately, the information throughput is link dependent, and as the noise or interference on the link increases, the throughput decreases. In an effort to improve the throughput on a short range, RF, packet switching data communications network, an adaptive ARQ strategy applied to Stop-and-Wait (SW) protocols was developed. To provide a system designer with flexibility, different adaptive strategies for different systems and link conditions were developed. Examples of information transfer between two stations using the adaptive SW protocol are presented. A simulation to compute the throughput efficiency of several adaptive SW protocols was performed. A comparison of the throughput efficiencies of the simulated adaptive SW protocol with the non-adaptive SW protocol showed good gains could be achieved using the adaptive strategy when the networks are subject to high channel bit error rates.

Adapative arq schemes and their performance evaluation under full‐duplex transmission

AbstractAdaptive ARQ (automatic repeat request) is an error‐control scheme in data transmission in which the number of successively transmitted data blocks and the data block length are adjusted according to the bit error rate. This scheme performs better in half‐duplex transmission than the conventional selective repeat (SR) and go‐back‐N (GBN) schemes when the bit error rate is either not known or varies with time.This paper proposes a control procedure for the full‐duplex adaptive ARQ scheme. In this procedure an observation period is defined and the data block length is adjusted dynamically according to the success of the data block transmission in the observation period. The throughput of this scheme is analyzed. The proposed scheme is compared with nine conventional schemes, including SR and GBN, in terms of performance. The results indicate that the performance of the adaptive ARQ scheme is very close to that of the fixed data block scheme in which the optimal data block length is selected statically. It is also shown that the performance of the adaptive ARQ scheme does not degrade as rapidly as in other schemes when the bit error rate increases.