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This paper deals with the modeling and analysis of the resequencing delay in time-division duplexing communication systems that adopt the Selective Repeat Automatic Repeat-reQuest error control strategy. Under the assumption that packet misordering at the receiving end is induced by channel errors, this paper proposes an analytical approach based on the absorbing Markov chain theory to accurately predict the impact of the resequencing delay on the quality of the provided services. Numerical results, which are derived by means of computer simulations, are also given to validate the proposed analytical model.

Link adaptation using adaptive modulation and coding (AMC) is a popular physical layer technique for efficient use of time-varying fading channels. Using a cross-layer approach, AMC and truncated automatic repeat request scheme at data link layer are jointly considered. For a convolutionally-coded M-ary quadrature amplitude modulation system under block fading channel condition, a variable rate transmission scheme that uses imperfect channel state information is derived. First, a closed-form expression for approximating packet error rate (PER) is found as a function of coded information rate. It is then shown that by solving an optimisation problem using this expression, optimum transmission rate can be determined in a way that maximises the spectral efficiency while satisfying an average PER constraint. Hence, the parameters in physical and medium access control layers are incorporated in the analysis.

SUMMARY Hybrid automatic repeat request (HARQ) and automatic repeat request (ARQ) of the terrestrial long-term evolution (LTE) system are designed considering the very short propagation delay of terrestrial environment. Therefore, when HARQ and ARQ are applied to the LTE-based mobile satellite communication system, the inefficiency is caused by the long propagation delay of satellite environment. This paper proposes the interaction method between HARQ and ARQ for the decrease of inefficiency in the LTE-based mobile satellite communication system. The existing concept of layered architecture about HARQ and ARQ is also maintained in our interaction method. Simulation results reveal that our proposed scheme can provide the larger spectrum efficiency than that of the non-interaction scheme in all environments. The performance improvement can be up to 2.04 times through the interaction method. Copyright © 2014 John Wiley & Sons, Ltd.

Initially developed for use in fixed networks, the ARQ (Automatic Repeat Request) technique was adopted in UMTS systems aiming the QoS improvement for data transmission. However, real time services like VoIP cannot benefits of ARQ, because of the related delay problems in WCDMA systems. With the advent of HSPA (High Speed Packet Access) and the LTE (Long Term Evolution) networks, there was a consequent redefinition of the ARQ functionalities, aiming to become possible to use it for real time services. Delay problems were minimized as a consequence of the facilities introduced for the new methods of ARQ generation. The main objective of this work is the definition of a methodology toward ARQ optimization relatively to the mean power required to transfer the information from the origin to the destination, accordingly to a given error probability.To reduce the amount of the power transfer in the uplink direction is of paramount importance for the minimization of interference levels as well as to economize battery of cellular equipment.Though the treatment here presented is focused to E-DCH (Enhanced Uplink Dedicated Channel) of HSPA systems, the results obtained are applicable to other related networks using ARQ techniques.

In this paper, we propose two dynamic error control schemes and apply them to the multichannel data communication system. The proposed schemes are based on the basic Stop-and-Wait ARQ and Selective Repeat ARQ protocols, The former and latter are used for the error controls in a round-trip time and among the multiple channels in a slot, respectively. The state of each channel is assumed as Markov chain with two states. The operations of the proposed schemes are described and their performances are evaluated through computer simulation. The numerical results show that the performances of the proposed schemes are improved remarkably comparing with the traditional scheme.

We consider the well-known Sliding Window Protocol which provides reliable and efficient transmission of data over unreliable channels. A formal proof of correctness for this protocol faces substantial difficulties, caused by a high degree of parallelism which creates a significant potential for errors. Here we consider a version of the protocol that is based on selective repeat of frames. The specification of the protocol by a state machine and its safety property are represented in the language of the verification system PVS. Using the PVS system, we give an interactive proof of this property of the Sliding Window Protocol.

Due to its efficiency, reliability and better channel and resource utilization, cooperative transmission technologies have been attractive options in underwater as well as terrestrial sensor networks. Their performance can be further improved if merged with forward error correction (FEC) techniques. In this paper, we propose and analyze a retransmission protocol named Cooperative-Hybrid Automatic Repeat reQuest (C-HARQ) for underwater acoustic sensor networks, which exploits both the reliability of cooperative ARQ (CARQ) and the efficiency of incremental redundancy-hybrid ARQ (IR-HARQ) using rate-compatible punctured convolution (RCPC) codes. Extensive Monte Carlo simulations are performed to investigate the performance of the protocol, in terms of both throughput and energy efficiency. The results clearly reveal the enhancement in performance achieved by the C-HARQ protocol, which outperforms both CARQ and conventional stop and wait ARQ (S&amp, W ARQ). Further, using computer simulations, optimum values of various network parameters are estimated so as to extract the best performance out of the C-HARQ protocol.

In this paper, we introduce Underwater Selective Repeat (USR), a Selective Repeat Automatic Repeat reQuest (SR-ARQ) mechanism for multiuser underwater acoustic networks. Our scheme exploits the typically large round-trip time (RTT) of underwater acoustic links to interlace the transmission of data and acknowledgment (ACK) packets, such that the transmitter never starts sending data packets when it should receive ACKs. No specific synchronization mechanism is required to do so. It is shown that the timing of point-to-point communications can be adjusted to optimize the performance of multiuser networks of a given size. Moreover, it is shown that the proposed strategy can be made robust to mobility, hence to time-varying RTTs. We provide detailed simulation results that assess the performance of USR as a function of the protocol parameters, both in static and in mobile networks. Based on these results, we propose an adaptive version of USR, whereby a node can modify its behavior (e.g., it can pack data transmissions more tightly or more loosely within one RTT) by reacting to packet errors induced by multiple-access interference.

This paper presents a queuing analysis method for automatic repeat request (ARQ) in network-coded cooperative transmission networks with dynamic radio link adaptation. An equivalent Nakagami-m channel model is derived for the network-coded cooperative system and a Finite State Markov Chain (FSMC) is modeled for conducting queuing analysis of packet transmission. Finally, the matrix geometry method is used to get the steady state probability distribution and delay statistics. Numerical results show that as the network coding method reduces the feedback delay, the corresponding total delay has a relatively decrease.

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.

Antenna selection is a low-cost low-complexity attractive approach in MIMO systems that capture many advantages of these systems. In this paper, our objective is to select the best antennas that maximize throughput with truncated selective repeat automatic repeat request at data link layer in zero-forcing MIMO receivers. We propose a novel binary particle swarm optimization method with throughput as its fitness function for joint transmit and receive antenna selection. The results of simulations demonstrate that the proposed throughput based antenna selection method has better performance compared to capacity based methods, and PSO algorithm can significantly reduce computational complexity.

Most multimedia applications implement some kind of packet losses analysis mechanism to trigger self-adaptation actions. However, error recovery mechanisms such as ARQ variants avoid packet losses at IP level. Then, there appears an impact into the delay that may indeed result on application-level losses due to samples arriving later than the scheduled playout time. In most cases such degradations are not detected until they are so severe than even losses at IP level appear. We propose a lightweight method that achieves a finer grain estimation. We prove mathematically the capability of modified versions of statistics of delay to predict the error ratio of the wireless link and the load of the wired backhaul. After deducing also simplified heuristics for proposed method, we analyze their estimation capabilities and provide guidance for selecting appropriate parameters. Finally, we test and adjust the algorithm to an specific scenario including mobile video streaming and VoIP calls.

Recently, relay technology has been adopted to enhance the coverage and performance of wireless networks such as Worldwide Interoperability for Microwave Access and Long-Term Evolution Advanced (LTE-A). However, using relays to forward packets may induce more packet losses than traditional single-hop wireless networks because transmissions are conducted through multiple radio links. When there are lost packets, relay stations (RSs) decide whether to retransmit these packets with automatic repeat request (ARQ) strategies. We observe that an improper ARQ strategy increases latency, blocked packets, and workloads on the multihop relay network. This paper proposes a new relay ARQ (RARQ) scheme, providing efficient acknowledgement to reduce packet latency and the number of blocked packets with small workloads. We also propose an analytic model to evaluate the performance of the proposed mechanism. Simulation results have validated the proposed model and demonstrated that our ARQ scheme outperforms conventional approaches.

Considering the DC-ARQ mechanism, this paper discussed the information transmission cycle of between vehicle nodes in the vehicle and road environment, and obtained the analytical expression of delay performance for GBN-ARQ retransmission protocol. The results obtained in the paper provide a way to improve vehicle ad-hoc network transmission capacity.

The relay-assisted, network-coding (RANC) automatic repeat request (ARQ) protocols are ARQ protocols that leverage both opportunistic retransmission and network coding for wireless relay networks. This paper proposes two single-relay RANC ARQ protocols, the listen-and-supersede (LS) protocol and the hold-and-proceed (HP) protocol. LS offers a fundamental limit to any single-relay RANC ARQ protocol. HP is a simple yet efficient RANC ARQ protocol with near-zero overhead. Moreover, we analyze saturation throughput and segment delay for both LS and HP. Their performances are compared with a representative cooperative ARQ protocol, the opportunistically forwarding (OF) protocol. Through extensive analysis and simulation results, we show that HP has a performance close to LS and outperforms OF significantly.

In this paper we introduce a novel Network Coding-based Medium Access Control (MAC) protocol for Vehicular Ad Hoc Networks (VANETs) that use cooperative Automatic Repeat reQuest (ARQ) techniques. Our protocol coordinates the channel access among a set of relays capable of using network coding in order to minimize the number of the total transmissions, thus enhancing the performance of the network in terms of Quality of Service (QoS) metrics. The proposed solution is compared to other cooperative schemes, while analytical and simulation results are provided to evaluate our protocol. (C) 2012 Elsevier Ltd. All rights reserved.

Recently there have been much interest in the performance improvement of maritime communication system. In the maritime communication system, the wireless channel is likely to be time-invariant and the retransmission scheme is not proper because it does not provide time diversity. For the improvement of reliability, we consider MIMO ARQ scheme using Alamouti-type signal which can provide space and time diversity. In this paper, we also propose the criterion of optimal retransmission order and provide its performance of error probability and packet throughput. The proposed MIMO ARQ scheme with optimal retransmission order has performance gain over random ordered MIMO ARQ and conventional Chase combining method. Therefore we expect that it can be adapted to the next generation maritime communication system.

The design of wireless local area networks (WLANs) with enhanced throughput performance have attracted significant amounts of attention in recent years. Based on the IEEE 802.11n standard, frame aggregation is considered one of the major factors to improve the system performance of WLANs from the medium access control (MAC) perspective. In order to fulfill the requirements of high throughput performance, feasible design of automatic repeat request (ARQ) mechanisms becomes important for providing reliable data transmission. In this paper, two MAC-defined ARQ protocols are proposed to consider the effect from frame aggregation for the enhancement of network throughput. An aggregated selective repeat ARQ (ASR-ARQ) scheme is proposed which incorporates the selective repeat ARQ scheme with the consideration of frame aggregation. On the other hand, for worse channel quality, the aggregated hybrid ARQ (AH-ARQ) mechanism is proposed to further enhance the throughput performance by adopting the Reed-Solomon (RS) block code as forward error correction (FEC) scheme. Novel analytical models for both the ASR-ARQ and AH-ARQ protocols are established with the consideration of interfering wireless stations. Simulations are conducted to validate and compare the proposed ARQ mechanisms based on the service time distribution and system throughput. Numerical evaluations show that the proposed AH-ARQ protocol can outperform the other schemes under worse channel condition; while the ASR-ARQ scheme is superior to the other mechanisms under better channel condition.

 Abstract—In this paper, an adaptive layered hybrid ARQ scheme for scalable video transmission is proposed. The layered hybrid ARQ scheme is performed based on group of pictures (GOP). The sender dynamically adjusts the transmission decisions according to the feedback of transmission results and the channel condition. Meanwhile, the transmission time management is also adopted. The earliest start time and the latest end time of transmission procedure for each GOP are introduced to limit the buffer size and control the transmission delay. Simulation results show that the proposed scheme performs better than the conventional layered hybrid ARQ scheme in terms of average PSNR of reconstructed video in a wide range of packet loss rate over bandwidth-constrained networks.

This paper presents a comprehensive cross-layer analysis framework on the performance of transmission control protocol (TCP) over free-space optical (FSO) links, which employ the automatic repeat request (ARQ) and adaptive modulation and coding (AMC) schemes. From the framework, we quantify the impacts of different parameters/settings of ARQ, AMC and FSO links on TCP throughput performance. We also discuss several optimization aspects for TCP performance.

Wireless broadband systems conceal the high error rates of their underlying channel from Internet protocols such as TCP using a windowed ARQ protocol. They also use a HARQ protocol at the physical layer where ACK/NACK feedback signals are sent for every packet. The higher layer “outer” ARQ protocol is needed due to the relatively high error rate of the HARQ feedback signals, especially NACK→ACK errors. The ARQ protocol feedback messages incur a relatively high protocol overhead but are sent relatively infrequently and corrects HARQ errors. Using a novel method of jointly coding successive HARQ feedback signals, this paper shows how NACK→ACK errors can be virtually eliminated and the outer ARQ protocol dispensed with. The method reduces protocol overhead and overall packet latency.

In this paper, we propose a cooperative automatic repeat request (ARQ) scheme for cognitive radio networks with full duplex (FD) capability. Cognitive system takes advantage of opportunities arising during primary's ARQ retransmission rounds for transmission of data whilst cooperating with primary network at the same time. This requires self-interference cancellation as well as known interference cancellation capabilities of destination nodes in the secondary network which are achievable with recent advances in FD technology. It is shown that the proposed protocol will achieve non-trivial throughput gain for the secondary network during primary's ARQ rounds without any degradation of the primary's performance. The validity of this method has been investigated in terms of data link layer Packet Error Rate (PER) as an important and practical figure of merit. Performance of the proposed protocol is analyzed mathematically and its effectiveness is verified via simulations.

Network Coding (NC) constitutes a promising technique of improving the throughput of relay-aided networks. In this context, we propose a cross-layer design for both amplifyand- forward (AF-) and decode-and-forward two-way relaying (DF-TWR) based on the NC technique invoked for improving the achievable throughput under specific Quality of Service (QoS) requirements, such as the maximum affordable delay and error rate.We intrinsically amalgamate adaptive Analog Network Coding (ANC) and Network Coded Modulation (NCM) with truncated Automatic Repeat reQuest (ARQ) operating at the different OSI layers. At the data-link layer, we design a pair of improved NC-based ARQ strategies based on the Stop-andwait and the Selective-repeat ARQ protocols. At the physical layer, adaptive ANC/NCM are invoked based on our approximate packet error ratio (PER). We demonstrate that the adaptive ANC design can be readily amalgamated with the proposed protocols. However, adaptive NC-QAM suffers from an SNR-loss, when the transmit rates of the pair of downlink (DL) channels spanning from the relay to the pair of destinations are different. Therefore we develop a novel transmission strategy for jointly selecting the optimal constellation sizes for both of the relay-to-destination links that have to be adapted to both pair of channel conditions. Finally, we analyze the attainable throughput, demonstrating that our truncated ARQ-aided adaptive ANC/NCM schemes attain considerable throughput gains over the schemes dispensing with ARQ, whilst our proposed scheme is capable of supporting bidirectional NC scenarios.

Selection cooperation is an effective solution for cooperative communications and the automatic repeat request (ARQ) protocol can provide additional diversity gain for wireless networks. In this work, considering a large network where direct transmissions only exist in the neighbors of each node, we investigate an improved diffusion selection cooperation protocol integrated with ARQ, and taking into account of the case that neighbors of the destination join cooperation at each ARQ retransmission. As a result, it can provide a complete insight into the performance analysis of the improved protocol. Moreover, the exact diversity-multiplexing-delay (D-M-D) tradeoff for each round of retransmission is derived. And the simulation results validate the accuracy of the improved scheme.

An efficient combination of repetitive coded L-PPM with an ARQ protocol is presented which can estimate the channel state and adjust the link transmission rate. The protocol operation is modelled as a Markov chain and analysis results indicate the enhanced performance of the proposed scheme under adverse channel conditions.

Error control consists of error detection and error correction in the communication system. The purpose of this research work is to reduce error in the wireless communication system by using the advantages of both error correction techniques which are forward error correction (FEC) and automatic repeat request (ARQ). Thus, error can be corrected without retransmission and also via retransmission(s) when needed. Combination of FEC and ARQ is known as Hybrid ARQ. In this paper, Hybrid ARQ system is designed using three components which are the irregular repetition code (IRC) as a simple code, bit-interleaved coded modulation with iterative decoding (BICM-ID) as a simple Turbo processing and ARQ. The HARQ system is enhanced by the extended mapping (EM) adopted in the mapping system. The performance of the systems is evaluated in the additive white Gaussian noise (AWGN). The results show the Hybrid ARQ with extended mapping (Hybrid ARQ-EM) outperforms Hybrid ARQ with standard mapping (Hybrid ARQ-SM). Hybrid ARQ-EM achieves low bit error rate BER (10-5) at low signal-to-noise ratio SNR which only 3.03dB close to the theoretical limit. The proposed system Hybrid ARQ-EM achieves 52 percent gain enhancement of SNR gap from the theoretical limit compared to Hybrid ARQ-SM. Hybrid ARQ-EM gives better performance although in worse channel condition.

As a promising technique, cooperative relaying has attracted more and more attention from academia and industry recently. In this paper, we investigate the scheme of Decode-and-Forward Two-way Relaying (DF-TWR) relying on a cross-layer design, which combines adaptive Network-coded Modulation (NCM) at the physical layer and truncated Automatic Repeat reQuest (ARQ) at the data link layer. The relay node utilizes Network- Coded Quadrature amplitude modulation (NC-QAM) where NCM imposes only a modest signal-to-noise ratio (SNR) degradation on the single-link QAM performance. Additionally, we derive the achievable spectral efficiency in closed-form for transmission over Rayleigh fading channels. It is shown that this combination of adaptive NC-QAM and truncated ARQ substantially improves the system's throughput compared to the schemes operating without ARQ.

In this paper, we consider a multiple-access broadcast channel (MABC) with ARQ feedback, in which M endusers wish to exchange messages with a central node or basestation. In this scenario, an end-user may overhear other endusers' messages prior to the re-transmission phase. We propose a new network coded (NCed)-ARQ scheme with reverse-link-assistance (RLA) that exploits this overheard information in uplink transmission to increase the downlink throughput. We derive throughput expressions for the new NCed-ARQ scheme in wireless additive white Gaussian noise with Rayleigh fading channel, which we numerically evaluate. For low/moderate SNRs, NCed-ARQ with RLA greatly improves the performance of downlink throughput.

In this paper, we are interested in the optimal redistribution of the available budget in average transmit power per packet among potential packet transmission attempts for improved Automatic Repeat reQuest (ARQ) protocol. A conventional ARQ protocol was combined in [5], with both Adaptive Modulation and Coding (AMC) and Power Control (PC) to improve spectral efficiency, while satisfying an average transmit power constraint. The optimal power level as well as the most adequate modulation and coding scheme (MCS) are jointly selected, as a function of the channel state. However, the selected power level remains the same for all retransmission attempts of the same packet. We propose in this paper to wisely distribute this optimally selected power budget among potential retransmissions of a given packet, such that throughput is further maximized, while keeping a fixed average power spent by packet. To do this, a heuristic algorithm based on a dichotomic search approach is performed. The enhancement in performance brought by the improved version of the ARQ protocol to the joint AMC-PC-ARQ scheme is then assessed.

In this paper, a cooperative spectrum sharing protocol is proposed for cognitive radio networks (CRNs) which operates in underlay mode with an automatic repeat-request (ARQ)- based primary user (PU) including primary transmitter (PT) and primary receiver (PR) nodes and a bidirectionally communicating secondary user (SU) which consists of the nodes S1 and S2. In ARQ-based PU, ACKnowledgement/Negative-ACKnowledgement (ACK/NACK) messages are send from PR to PT and listened by S1 and S2 to control the PU's package achievement. PU transmits its package by accessing the spectrum alone or by cooperating with SU or under interference caused by SU. It is shown by analytical and simulation results for the throughputs of PU and SU that the proposed protocol significantly improves the PU's throughput compared to conventional non-CR model while stabilizing the secondary user throughput.

This paper carries out a performance evaluation of network coding (NC) for power line communication (PLC) systems based on simulation and theoretical results. NC is deployed at the data link layer (DLL) where it could potentially improve the routing protocol, the MAC scheduler and the ARQ mechanisms. In this paper we focus solely on the combination of NC and ARQ mechanisms. Nevertheless, based on the G.hn standard, we are able to achieve a significant improvement in data rate and latency. We show the optimal setup of NC parameters like generation and symbol size to achieve the best performance of the ARQ mechanism in PLC systems.

The new standard IEEE 802.11s enables vendor-independent wireless mesh networks based on the 802.11 WLAN technology. Transmission Control Protocol (TCP) is the most widespread transport protocol for reliable data delivery and still the basis for many network applications. TCP supports different mechanisms for flow and congestion control. However, designed for wired networks, it does not consider the dynamics of wireless networks and especially multi-hop wireless mesh networks. In addition, 802.11s provides own mechanisms such as Automatic Repeat Request (ARQ) for frame retransmissions to hide wireless loss from the upper layers. Being transparent to each other, retransmission schemes on both layers may interfere and operate redundantly, if not properly adjusted. We study the effects of ARQ retry limit variation on TCP throughput in a real-world multi-hop 802.11s test bed. As a result, we suggest ARQ adaptation based on the 802.11s standard's Airtime Link Metric (ALM) for path selection, serving as indicator for overall frame travel time. Our proposed approach solely relies on standard features and imposes no modifications to 802.11s or TCP.

Fifth generation (5G) wireless systems will provide connectivity for a wide range of new applications with diverse requirements. In part, the network needs to support ultra-reliable communications with low-latency (URLLC) for mission-critical applications. For these applications, the generated data should be delivered with a limited number of transmission attempts with high success probability. This paper considers the optimal transmission and resource allocations for URLLC in cellular systems. The resource allocations are derived for the fixed and adaptive transmission attempt assignments. The analysis results reveal that both fixed and adaptive transmission assignments, applicable to automatic repeat request (ARQ) and hybrid ARQ (HARQ) schemes, can reduce the required resources compared to the equal transmission assignment.

The proposed model is a virtual connection managed by the transport protocol with a forward error correction mechanism for selective repeat mode in the form of Markov chain with discrete time. The analysis of the impact of protocol parameters window size and the duration of the timeout of waiting confirmation, the likelihood of distortion of the segments in the individual links of the transmission path data, the duration of the round-trip delay, the parameters of mechanism to restore the distorted segments (without retransmissions) on throughput of a transport connection. In the area of protocol parameters, the characteristics of the transmission channel and parameters of the forward error correction mechanism found in the area of superiority of the management procedures of the transport protocol with forward error correction over the classic procedure with decision feedback on the criterion of the throughput of a transport connection. The expediency of applying of the method of forward error correction for transport links with large round-trip delay.

In this paper, a handshaking-based MAC protocol that employs a cooperative ARQ is proposed for the underwater wireless sensor networks (UWSNs). During a handshaking, the source node identifies the neighbors that are qualified for cooperative communication and then inform the destination node of the existence of cooperators. In case that an erroneous data packet is received, the destination makes a request for retransmission of the erroneous packet from the cooperators first, not from the source. Simulation results show that the proposed scheme has higher data throughput than the existing MACAU-ACK protocol.

Networks-on-Chip (NoCs) are the backbone of Multiprocessor Systems-on-Chip (MPSoCs). In this paper, we perform a formal worst-case communication time analysis of Automatic Repeat reQuest (ARQ) protocols for NoCs. Therefor, we integrate the transport layer analysis for general networks and the network layer analysis for NoCs. An ARQ variant optimized for DMA transfers (DMA ARQ) is introduced and analyzed. Experimental evaluation with Stop-and-Wait, Go-Back-N, and DMA ARQ, in the context of real-time memory traffic is presented, including both error-free and error cases. DMA ARQ achieves a factor 6 improvement on latency bounds over conventional Stop-and-Wait.

The steady-state performance of general network coding nodes is investigated, when data are transmitted in packets based on the go-back-N automatic repeat request (GBN-ARQ) or selective-repeat ARQ (SR-ARQ) error-control scheme. A general network coding node is assumed to have H incoming links that provide packets for forming the coded packets transmitted by one outgoing link. Each of the incoming and outgoing links is assumed to have some buffers for temporarily storing the data packets. The state transitions of network coding nodes employing GBN-ARQ or SR-ARQ are analyzed, which shows that the operations of a general network coding node can be modeled by a finite state machine. Therefore, the expressions for the steady-state throughput of general network coding nodes are derived based on the properties of finite-state machines. Furthermore, the throughput performance of network coding nodes is investigated by both simulations and evaluation of the expressions obtained. The studies show that the simulation results converge closely to the numerical results, which justify the effectiveness of the analytical expressions derived. Furthermore, the studies show that the packet error rate, the capacity of buffer, and the number of incoming links may impose significant impact on the performance of general network coding nodes.

An efficient cooperative Automatic Repeat reQuest (ARQ) protocol for distributed space-time coded cooperative networks is proposed in this paper. Conventional cooperative ARQ protocol just utilizes the relays which can decode the packet from the source in direct transmission. However, relays which can not receive the packet successfully have the ability to listen to the retransmission and decode the packet with high probability. Therefore, we consider to let these relays join in the next possible retransmission. We prove that the proposed cooperative ARQ protocol has a lower packet loss rate and average retransmission number than conventional ARQ protocol. Finally, the simulation results verify our theoretical results and show that the proposed ARQ protocol is suitable for the relay networks where the source node is close to the relay nodes.

Automatic repeat request (ARQ) protocols are normally studied under slow-fading or quasi-static channel assumption where the fading coefficients are assumed to remain fixed during the transmission of a codeword or for the duration of all ARQ retransmission rounds, respectively. This letter investigates the performance of basic ARQ and incremental redundancy hybrid ARQ protocols in fast-fading channels where a number of channel realizations are experienced in each retransmission round. Long-term throughput, delay-limited throughput and outage probability of the ARQ schemes are obtained. Compared to slow-fading and quasi-static channels, a fast-fading channel results in a higher performance for both basic and incremental redundancy ARQ. The fast-fading channel, however, can be mapped to an equivalent slow-fading model at low signal-to-noise ratios. Finally, we show that the efficiency of ARQ protocols is overestimated if the fast-fading variations during a codeword transmission are approximated by their average value.

In this paper, we propose a novel protocol called a Multi-hop Diversity Transmission protocol in which the retransmission is realized by a relay that is Nearest to a current Source (MDTNS). We derive the mathematical expressions of the packet error rate (PER) and the average number of transmissions over Nakagami-m fading channels, and verify them by Monte Carlo simulations. The simulation results show that the MDTNS protocol improves the performance of the network in terms of PER when compared to the Multi-hop Diversity Transmission protocol in which the retransmission is done by a relay that is Nearest to Destination (MDTND) and to the conventional multi-hop transmission (CMT) protocol.

This paper proposes a new retransmission scheme for achieving high-speed transmission by reducing the retransmission delay time caused by packet loss. High-speed data packet transmission can be realized by sending user datagram protocol (UDP) packets continuously over long-distance wireless systems. The UDP characterizes connectionless communication, requiring the use of a retransmission scheme for reliable quality. However, the transmission speed will reduce with repeated retransmissions over time. The key advantage of the proposed scheme is that the retransmission waiting time can be dramatically reduced by transmitting data packets in descending order from the last data packet. It is verified via a computer simulation that the average peer-to-peer network configuration receiving time can be approximately halved and a 20% improvement in throughput with a packet error rate of 0.1 can be achieved by the proposed scheme.

This work investigates the progressive linear precoder design for packet retransmissions in multi-input multi-output (MIMO) systems with multiple codewords and automatic repeat request (ARQ) bundling feedback. Assuming perfect channel state information, a novel progressive linear ARQ precoder is proposed in the perspective of minimizing the packet error rate. We devise the ARQ precoder by combining power loading and subchannel pairing between current retransmission and previous transmissions. Furthermore, we extend the design to the case that the channel estimation error exists. Numerical results show that the proposed scheme can improve the performance of MIMO ARQ systems significantly regardless of the channel estimation error.

For reliable data transmissions, WiMAX systems support automatic repeat query (ARQ) that operates at the upper MAC and hybrid automatic repeat query (HARQ) that operates at the lower MAC and PHY. ARQ and HARQ schemes have their own weakness that results in low throughput and high delay in WiMAX systems. Although ARQ and HARQ schemes can complement with each other, they operate independently. Some studies focus on the benefits of the interaction between ARQ and HARQ schemes, but these studies have limitations. In this paper, we propose an adaptive ARQ and HARQ interworking scheme to provide reliable transmissions without performance degradation in WiMAX systems. The proposed scheme has five features that are designed to solve the weaknesses of the ARQ and HARQ schemes. We compare the proposed scheme with existing schemes that utilize the ARQ and HARQ interaction through simulations, and the simulation results show that the proposed scheme shows improved performance over existing schemes.

The Primitive Bit Error Rate is much higher in severe electronic-magnetic environment, which results in much more retransmissions for an ARQ data transceiver; this means a lower efficiency of transmission. To cope with the above problem, this paper proposes a new mechanism, which is based on majority-voting. Through theoretical analysis and simulations, this novel approach shows better performance than those conventional ones.

Although the wireless communication systems offer limitless possibilities of service utilization, these systems are not error free. Variable error rate of these systems is the main reason of being concerned with error control techniques. Selection of suitable error control techniques is very important and depends on performance. We can choose from three basic techniques Send-and-wait, Go-back-N and Selective repeat. Nowadays, Hybrid Automatic repeat request techniques have the best aptitude for solving the problem with error detection. The thesis deals with division and functioning of Automatic repeat request schemes. In particular, we focus on the efficiency criterions of Automatic repeat request schemes--throughput and computational complexity. These criterions are presented based on simulations for Go-back-N scheme.