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In this correspondence, we present an efficient protocol for the delay-limited fading ARQ single relay half-duplex channel. The source is using an automatic retransmission request (ARQ) retransmission protocol to send data to the relay and the destination. When the relay is able to decode, both the relay and the source send the same data to the destination providing additional gains. The proposed protocol exploits two kinds of diversity: (1) space diversity available through the cooperative (relay) terminal, which retransmits the source's signals and (2) ARQ diversity obtained by leveraging the retransmission delay to enhance the reliability. The performance characterization is in terms of the achievable diversity, multiplexing gain and delay tradeoff for a high signal-to-noise ratio (SNR) regime. Finally, we show the benefits of power control on the diversity by controlling the source's power level over the retransmission rounds.

We propose two novel automatic repeat request (ARQ) strategies for relay cooperative system over Rayleigh fanding channel: one uses relay ARQ and the other destination ARQ. The BER performace of these two strategies is derived in fast block fading. Numerical analysis and simulation show the systems can get more performace gain when the inter-channel (the source to the relay) quality is bad in the relay ARQ strategy. In the destination ARQ strategy, when the uplink qualities of the source and relay to the destination are poor, the average received SNR of the destination is much low, the systems performce can be improved efficintly.

Reliability-based hybrid ARQ (RB-HARQ) is a kind of incremental-redundancy ARQ recently introduced. In the RB-HARQ, the receiver returns both NAK signal and set of unreliable bit indices if the received sequence is not accepted. Since each unreliable bit index is determined by the bitwise posterior probability, better approximation of that probability becomes crucial as the number of retransmissions increases. Assuming the systematic code for the initial transmission, the proposed RB-HARQ scheme has the following two features: (a) the sender retransmits newly encoded and interleaved parity bits corresponding to the unreliable information bits; (b) the retransmitted parity bits as well as the initial received sequence are put all together to perform the message passing decoding i.e. the suboptimal MAP decoding. Finally, simulation results are shown to evaluate the above two features.

We present a queueing model for performance analysis of go-back-N (GBN) and selective repeat (SR) automatic repeat request (ARQ) protocols in wireless networks using dynamic radio link adaptation with non-instantaneous feedback. Link adaptation technique allows multi-rate transmission which is assumed to be achieved through adaptive modulation and coding. The radio link level queueing models for these two ARQ protocols are formulated in discrete time where the exact queue length and the delay statistics are obtained by using matrix geometric methods under different feedback delay values, channel and system parameters. The link layer delay statistics are useful in many ways, for example, to perform packet level admission control under statistical delay constraints. We validate the analysis by simulation and discuss useful implications of the analytical model on system performance. For dynamic link adaptation, the mode switching thresholds for the received signal-to-noise ratio (SNR) can be chosen to obtain very good link level delay performance. This SNR partitioning is shown to achieve significant cross-layer design gain compared to the case where the mode switching thresholds are chosen to maximize the physical layer throughput.

The adoption of satellite systems in providing broadband transmissions to mobile users such as trains, buses and vans is expected to be an interesting solution. The scenariowe considered refers to a hybrid network architecture, where a geostationary satellite forward link and a terrestrial 3G return link are used in order to exploit both the high bandwidth of a satellite channel and the lower propagation delay of a terrestrial path. The resulting round-trip delay is much shorter than that one experienced by using both the forward and return link via satellite. This is particularly appealing for overcoming the TCP efficiency degradation in high delay-bandwidth product and error prone channels. In this hybrid scenario, we used simulation results to compare the goodput of four of the most popular TCP variants, in the presence of a GOOD-BAD satellite channel, as the one experienced by mobile users. We applied an AdaptiveCoding and Modulation (ACM) technique as well, and studied its impact on TCP efficiency, when used both alone and in cooperation with an Automatic Repeat reQuest (ARQ) scheme of the Selective Repeat (SR) type with low persistency. Results obtained indicate that this hybrid architecture is advantageous for TCP transmissions in terms of average goodput, and that ACM is effective only if it is jointly used with ARQ schemes.

In this paper, we propose a novel highly reliable packet transmission protocol for ad-hoc wireless networks without deciding the route from a source node to a destination node in advance. The proposed protocol uses distributed surrounding nodes as transmitters of the retransmission packet when the transmitted packet contains an error. In this protocol, when a packet is not correctly received at the destination node, the source node and the surrounding nodes that have correctly received the packet simultaneously retransmit the same data packet to the destination node. The transmitting timing is triggered by the control packet transmitted from the source node. These operations are repeated until the packet reaches to the destination node like automatic repeat request (ARQ). Moreover, the retransmitted packet is encoded by one branch of the space time block code (STBC) for improving the performance with the network diversity effect. We call this method as STBC Distributed ARQ scheme. The performance of the proposed scheme is evaluated by the computer simulations.

This paper proposes an OFDM mobile radio packet system that employs a new protocol of automatic repeat request (ARQ) for nonlinear multiuser detection (MUD) with log likelihood ratio combining (LC) on the appropriate bits. The conventional metric combining (MC) MUD separates collided packets by using nonlinear MUD, accumulates the Euclidian distance metrics of the received subcarrier symbols in the packets, and then achieves throughput improvement. However, when MC-MUD detects a packet error, it makes user terminals retransmit the same packets so as to reproduce the collision of the same packets. The proposed LC-MUD scheme simplifies the ARQ protocol and requires no reproduction of the same packet collision. The computer simulations demonstrate the superior throughput of LC-MUD to that of MC-MUD, and further improvement due to adaptive modulation and coding (AMC) optimized for the nonlinear MUD in LC-MUD.

Efficient H.264 video transmission over wireless/mobile networks becomes dominant, because H.264 is adopted as a dominant video coding standard in mobile broadcasting and in other advanced video streaming. However, wireless video transmission suffers from poor wireless channel conditions, such as high bit error rate and error bursts resulting from channel fading and radio interference. In this paper, a novel design of unified error-control with cross-layer interactions over IEEE 802.11e wireless LAN and an efficient low-overhead ARQ scheme are proposed. This framework combines cross-layer error protection techniques composed of error correction code in the link/MAC layer, erasure code in the application layer, and ARQ across the link/MAC layer and application layer. In this framework, a guideline for quality improvement of the cross-layer approach is also developed and offered. In addition to the unified cross-layer error-control framework, an efficient MAC-level ARQ scheme with low-overhead is also proposed. The several cases of low-overhead ARQ scheme combined with or without cross-layer interaction are compared and discussed for performance evaluation.

In this paper, we study channel estimation and equalization for a class of bandwidth efficient automatic repeat request (ARQ) systems. In these systems, retransmissions achieve bandwidth efficiency through symbolwise downsampling. Unlike a standard ARQ scheme, in which an erroneous packet is fully repeated, more sophisticated hybrid ARQ systems retransmit a recoded data packet. However, many of these ARQ schemes do not consider the integration of ARQ protocols with receiver signal processing such as channel estimation and signal detection. In this paper, we present a joint multichannel estimation algorithm that exploits the structure of a symbolwise downsampled ARQ equipped network. We show that this new method can improve the identifiability conditions for channel estimation as well as the overall system performance

A cross-layer design is developed for quality-of-service (QoS)-guaranteed traffic. The novel design jointly exploits the error-correcting capability of the truncated automatic repeat request (ARQ) protocol at the data link layer and the adaptation ability of the adaptive modulation and coding (AMC) scheme at the physical layer to optimize system performance for QoS-guaranteed traffic. The queuing behavior induced by both the truncated ARQ protocol and the AMC scheme is analyzed with an embedded Markov chain. Analytical expressions for performance metrics such as packet loss rate, throughput, and average packet delay are derived. Using these expressions, a constrained optimization problem is solved numerically to maximize the overall system throughput under the specified QoS constraints

Conventional adaptive transmission schemes perform poorly in wireless correlated slow-fading channels. A cross-layer adaptive transmission scheme combined with selective repeat automatic repeat request (SR-ARQ) is proposed. We apply a multi-state Markov system model for analyzing the performance of systems and optimizing the selection of modulation levels and packet sizes in correlated fading channels, which is also described by a finite-state Markov chain. A general closed-form expression of the average throughput for our suggested scheme is presented. Numerical results show that our adaptive scheme combined with SR-ARQ can obtain good performance in correlated fading channels.

This paper studies the situation where multiple IP flows are aggregated over a single wireless channel and an error recovery by retransmissions is performed by Selective-Repeat (SR) ARQ. We propose MQ-PFRS (Multi-QoS Per-Flow Resequencing) ARQ that provides a differentiated service for an IP flow depending on its QoS class, such as real-time or non-real-time. MQ-PFRS ARQ eliminates interferences among IP flows by resequencing received packets independently for each IP flow. It also controls the maximum packet delay by limiting the persistency of retransmissions and the maximum resequencing time for each packet. This paper also presents an analysis of the probability distribution of real-time packet delays. Simulation results show that the delay variation of real-time traffic is effectively controlled by proposed MQ-PFRS ARQ and the packet delay distribution is quite consistent with the results of the analysis. This means that MQ-PFRS is effective for handling multiple QoS classes of IP flows and the quality of real-time traffic transferred by the scheme can be predicted by the analysis.

In this paper, we present a new method to analyze the throughput and delay of the selective-repeat (SR) automatic repeat-request (ARQ) protocol. Previous work on SR ARQ has concentrated on reliable feedback or two-state Markovian feedback errors. We solve a wider class of problems by characterizing both the forward and reverse channels by general hidden Markov models (HMMs). The moment-generating function (MGF) technique is used to find throughput and delay. To calculate the MGF, we construct matrix signal-flow graphs for the hidden Markov process. This procedure can be useful for a variety of other HMM problems, and is of interest by itself. Practical issues such as erasure errors and timeouts are included in our analyses, which are verified by extensive simulations

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.

This paper deals with the application of H-ARQ techniques to reliable end-to-end data communications with adaptive adjustment of parameters according to the type of business in aerospace information network, whose applications have to cope with accurate Quality-of-Service (QoS) requirements. In the adaptive H-ARQ strategy, we adopt cell-level RS code as Forward Error Correction (FEC) coding scheme. Retransmissions of the corrupted data block are combined at the receiver with the previously received sequences of the same data block for decoding. Particularly, adaptive adjustment of FEC coding parameters and ARQ retransmission times by the type of business joint the state of network. As a result, it has been possible to allow each business a better QoS, in terms of error rate, throughput, and delivery delay.

In the last decade, cooperative communication and network coding techniques gained rising attention. Based on these techniques, this paper introduces a novel protocol called cooperation and network coding based MAC (CNCMAC) for vehicular ad-hoc networks (VANETs). It employs cooperative automatic repeat request (ARQ) and network coding techniques to enhance throughput. The CNC-MAC protocol works in two phases. In the first phase - cooperation - data is sent to relay nodes. The second phase - network coding - minimizes received packets. The performance of the CNC-MAC protocol is compared with cooperative ARQ-MAC, another common protocol in this domain. The simulation results indicate that CNC-MAC outperforms ARQ-MAC.

Various Automatic Repeat Request (ARQ) schemes have been used to combat errors that befall information transmitted in digital communication systems. Such schemes include simple ARQ, mixed mode ARQ and Hybrid ARQ (HARQ). In this study we introduce extended ARQ schemes and derive expressions for their throughput performance. We then compare their performance with mixed mode ARQ schemes where it is shown that extended ARQ schemes outperform the mixed mode ARQ schemes. We also show how the parameters for the schemes can be chosen to maximize performance. Keywords : ARQ, extended ARQ, HARQ, mixed mode ARQ, throughput

Reliable data transport has always been one of central issues in the area of communication networks. In this work, we investigate the possibility of enhancing reliability of selective repeat (SR) automatic repeat request (ARQ) by integrating network coding techniques into it. Through extensive simulation experiments, we analyze packet transport performance, e.g., throughput and delay, against various parameters including network transmission delay, packet loss rate, etc. Based on findings through simulation experiments, we then suggest design and operation guidelines and address harmonizing issues in integrating SR ARQ and network coding.

This paper analyzes end-to-end packet error rate of decode-and-forward cooperative networks over Rayleigh fading. Packet error rate expressions are derived when node cooperation is applied with a selective repeat automatic retransmission request scheme and confirmed by Monte-Carlo simulations. The impact of average signal-to-noise ratio values, network dimension and number of retransmission attempts when maximal-ratio combining is performed at the destination are discussed.

The long propagation delay and the high bit error rate of underwater acoustic channel greatly affect the performance efficiency of underwater acoustic networks (UWANs). In this paper, we propose three ARQ schemes for UWANs, namely selective repeat-ARQ, Type-I Hybrid ARQ and Type-II Hybrid ARQ, where the transmissions of data and acknowledgment packets are interlaced. The proposed ARQ schemes are designed in the multiuser UWAN with single-hop network topology, and the media access control is the time division multiple access. The performance of the proposed ARQ schemes, in terms of the transmission efficiency and the average transmission delay of a packet, is analyzed, and the closed-form expressions of the performance metrics are derived. By comparisons, the best choices of the ARQ scheme in different network parameter scenarios are given.

Relay networking is an appealing option for operators to solve coverage issues and to improve performance without a need to deploy more complex macro sites. In this paper we look at several options for re-transmission mechanisms that are already adopted in wireless standards, such as 3GPP LTE-Advanced and IEEE 802.16. In particular, we consider a hop-by-hop HARQ operation without any ARQ on top of it, and also with ARQ working in the end-to-end and hop-by-hop modes. We run extensive simulations for the aforementioned configurations and present our results indicating that HARQ should be ideally complemented by the ARQ mechanism. As for the exact ARQ mode, the hop-by-hop ARQ provides better performance that however comes at its own implementation cost.

Real-time applications over wireless networks often suffers from jitter, delay and packet loss. The traditional techniques for error control are FEC (Forward Error Correction) and ARQ (Automatic Repeat Request). In this paper a hybrid FEC/ARQ mechanisms with limiting the slots number between the loss of the last retransmission of the original block n and the reception of block n + φ is analyzed in an environment of real time applications. We assume that the packet size increases when adding redundancy so that the amount of useful information contained in a packet is unchanged. We evalute analytically the performance of TFRC (TCP Friendly Rate Control) and ARC (Analytical Rate Control Protocol) as a function of the parameters of the FEC scheme, the limit number of retransmission used by ARQ scheme and the number of slots threshold Sth. We show that the combination of FEC and ARQ with limiting the Sth reduces the number of retransmissions and keeps a reasonable delay for real time traffic in wireless networks.

In wireless sensor networks, cooperative communication can combat the effects of channel fading by exploiting diversity gain achieved via cooperation communication among the relay nodes. A cooperative automatic retransmission request (ARQ) protocol based on two-relay node selection was proposed in this paper. A novel discrete time Markov chain model in order to analyze the throughput and energy efficiency was built, and system throughput and energy efficiency performance of proposed protocol and traditional ARQ protocol were studied based on such model. The numerical results reveal that the throughput and energy efficiency of the proposed protocol could perform better when compared with the traditional ARQ protocol.

International audience; A new coding mechanism is provided to automatically detect and recover lost packets in wireless lossy networks. Contrary to the majority of automatic repeat request (ARQ) algorithms relying on acknowledgment, our mechanism extracts feedback on packet delivery by analyzing received network coded messages and automatically reacts when packet loss is sensed. Compared to traditional end-to-end ARQ, our proposed mechanism shows significant reduction in the number of transmissions required to exchange the same amount of data.

When data is transmitted over error-prone channels, portions of data may be corrupted due to many reasons, including multipath fading, interference, signal attenuation, and shadowing. Even if there is only one bit uncorrectable, the data block or packet will be considered as invalid, and will be discarded. The Automatic Repeat reQuest (ARQ) is an important mechanism to recover lost packets transmitted over either unstable or congested networks. An ARQ mechanism is also implemented in the 4G wireless networks on the link layer, where a receiver can request its sender to retransmit invalid packets. However, retransmission requires additional bandwidth, and it can result in longer delay. For some applications, such as layered video streaming, the utility of each packet of a stream can be different. The QoS requirements of different flows can vary as well. In this paper, a priority-based scheduling method for retransmission is proposed for wireless channels with limited bandwidth resources. For intra-flow traffic, which can be treated as several link-layer flows, the priorities can be assigned to the flows using different QoS classes. A dynamic utility function is developed for the scheduling of invalid packets such that the overall utility can be improved. The amount of resources for retransmission is also regulated dynamically such that each flow can occupy reasonable bandwidth. The improved performance is verified with simulation results.

We consider a point-to-point wireless link with automatic repeat request (ARQ) based packet transmission where both the transmitter and receiver nodes are energy harvesting (EHNs). Transmitter EHN has access to low-grade channel state information (CSI) as it is implicitly obtained from ARQ feedback. Furthermore, signal processing tasks such as sampling and decoding at the receiver EHN can be interrupted if there is insufficient energy in the battery that cause loss of packet and wastage of harvested energy both at the transmitter and receiver EHNs. We propose selective sampling (SS) scheme where only part of the transmitted packet is sampled and stored depending on the receiver nodes stored energy. SS information (SSI) is then fed back to the transmitter. Packet decoding is not performed until full packet is constructed. Hence, we modify the conventional ARQ messages, i.e., ACK/NAK by adding few more bits to carry additional SSI as well. Another objective is to find the optimal power allocation policy to adapt to the low-grade CSI and SSI available at the transmitter such that harvested energy can be utilized efficiently especially at the receiver. Furthermore, using a decision-theoretic framework, we propose greedy power allocation scheme to evaluate the performance of the proposed retransmission scheme. In numerical examples, we illustrate that our proposed scheme has lower average packet transmission time and packet drop probability (PDP) compared to the equal power allocation and greedy power allocation with conventional retransmission scheme.

Hybrid automatic repeat request (HARQ) can make efficient and reliable transmission possible for radio communications. However, in the HARQ scheme, packet control information (PCI), such as HARQ block identifiers (HARQ block ids) in selective repeat ARQ (SR-ARQ), are required and the reduction of PCI overhead is an issue. In particular, type-II HARQ handles a large amount of PCI because it includes the HARQ block ids and sub-block ids. The sub-block id identifies the set of parity bits in the HARQ block of the corresponding sub-block, and is used to combine the sub-blocks. This report proposes a method of PCI reduction suitable for type-II HARQ with SR-ARQ. The method can inform the HARQ block id and sub-block id of each HARQ block by sending only the information on how many HARQ blocks are contained in each 1st, 2nd, 3rd, and 4th transmission group. The estimated size of reduced PCI and simulation results of our TDD communication system confirms that the proposed method greatly reduces PCI and improves data throughput compared to a conventional method.

In this paper, we investigate throughput efficiencies of relaying algorithms with the ideal selective-repeat ARQ in Flying Ad hoc Networks (FANETs). We consider a network of three nodes: the source, the destination, and the relay. We propose Markov models of three relaying algorithms: chunk-by-chunk algorithm, fifty-fifty algorithm, and ratio-based algorithm. Throughput efficiencies of these algorithms are compared. Simulation results are obtained for scenarios with stationary and mobile relay node.

H.264/SVC is a promising coding standard in wireless transmission with scalable features. It can adapt video qualities to the unstable bandwidth. To optimize the receiving side's video quality for H.264/SVC transmission over wireless networks with package loss, a novel and simple loss impact estimation based automatic repeat request (ARQ) algorithm is proposed in this paper. The proposed ARQ algorithm determines the best packet to be transmitted at each transmission opportunity. This is determined from what impact losing the packet would have and the real-time constraints. The weights for these influences are dynamically selected. The loss-impact for each packet is quantitatively evaluated by a proposed distortion function, considering macroblock level information and temporal error propagation. The results of simulation indicate that the proposed ARQ algorithm outperforms all referenced approaches in both interdependent and burst loss conditions.

A new scheme for error-free transmission is presented which uses optimized combination of adaptive modulation and coding (AMC) and automatic repeat request (ARQ). Using conventional error correction codes with finite length, a limited value of packet error rate (PER) is inevitable. More powerful codes with more extra parity bits results in lower PER, however, at the cost of more transmit power per bit which is limited by average power constraint. Remained erroneous packets may be detected by error detection codes and be substituted by retransmission request in ARQ. However, when error correction capability is weak, throughput decreases due to increase of required retransmissions. In this article a method for optimum combination of error correction codes in AMC and error detection codes in ARQ is provided. In practice, due to estimation error and time variant channels, noisy and outdated channel state information (imperfect CSI) is available which restricts providing exact instantaneous PER constraint. To satisfy instantaneous PER constraint based on imperfect CSI, a novel technique is designed in this paper. Numerical evaluations indicate the efficiency of the proposed design.

The article is dedicated to software implementation of the packet loss correction ARQ algorithm at application layer (AL-ARQ) for streaming in the wireless local area network. Functioning of the developed software verified experimentally using simulation of wireless transmission by the Gilbert model. Moreover, the algorithm was optimized for MPEG streaming by introducing the packets prioritization for retransmission taking into account time to deadline and frame type. It was experimentally obtained that the optimization had increased quality of service and quality of experience relatively to not optimized version of the algorithm.

Reducing the in-order delivery, or playback, delay of reliable transport layer protocols over error prone networks can significantly improve application layer performance. This is especially true for applications that have time sensitive constraints such as streaming services. We explore the benefits of a coded generalization of selective repeat ARQ for minimizing the in-order delivery delay. An analysis of the delay's first two moments is provided so that we can determine when and how much redundancy should be added to meet a user's requirements. Numerical results help show the gains over selective repeat ARQ, as well as the trade-offs between meeting the user's delay constraints and the costs inflicted on the achievable rate. Finally, the analysis is compared with experimental results to help illustrate how our work can be used to help inform system decisions.

ARQ (Automatic Repeat Request) is an error control protocol. Packet combining (PC) scheme is an extended ARQ, and Aggressive Packet Combining (APC) scheme is another error correction scheme. In PC & APC scheme two & three copies of the packet are send in all channel condition respectively. The wireless channel for packet transmission is not only random but time varying. In this paper we investigate the exact analysis of Packet combining scheme and Aggressive Packet combining scheme. We proposed a combined protocol of PC and APC for time varying channel and find that it will offer higher throughput and lower mean energy consumption at high BER (bit error rate) with medium and large packet size.

In this paper, a new throughput-based transmit antenna selection (AS) scheme is evaluated. First, a closed-form solution for the throughput rate of a multiple-input multiple-output (MIMO) system, with a truncated selective repeat automatic repeat request (TSR-ARQ) or selective repeat plus go-back-N automatic repeat request (SR+GBN-ARQ) protocol at the data link layer, is proposed. In addition, a throughput-based AS technique with adaptive modulation is also investigated. For this purpose, the throughput and packet error rates of a MIMO system with a transmit AS and TSR-ARQ protocol at the data link layer are analyzed. This study is conducted in 2 different cases. In the single-transmit AS case, the probability density functions (PDFs) of the throughput and packet error rates at the data link layer are derived. Moreover, in the case with multiple-transmit AS, a lower bound for the throughput rate and an upper bound for the packet error rate at the data link layer are determined. Consequently, the PDFs of these lower and upper bounds are extracted.

Now-a-day, relay technology has been adopted to improve the coverage, reliability and quality-of-service in wireless network. This paper proposed a new relay selection method with Automatic Repeat reQuest (ARQ) scheme. In this paper, multiple relay are used to transmit the data from source to destination node by using max-relay. To find proper node this paper proposed a new relay selection method based on euclidean distance method. This paper also proposed an Automatic Repeat reQuest (ARQ) mechanism i.e. stop and wait Automatic Repeat reQuest (ARQ) scheme. When any error occurs in the relay at data transmission time then relay use Automatic Repeat reQuest (ARQ) strategy. This new scheme proposed for reduce the packet loss, network loss and delay on the wireless network.

Maximizing the lifetime of sensor networks is a major challenge. In a sensor network, the nodes communicate with each other to pass the information to a data sink. These nodes have limited energy resource, and to increase the lifetime of the network, it is necessary to design communication protocols which aim at reducing the consumed power. Several advanced communication protocols for sensor networks have been already proposed in order to optimize system performance using the BER criterion. We can classify them mainly in two categories: those which are based on network coding by inserting relays between sensors and destination, and those which use ARQ protocols. In this paper we compare these different solutions using a new criterion: the consumed power. The goal is to obtain a conclusion on the judicious choice of the protocol according to the range of SNR's in a context of small network (we consider the BAN context for example). The simulation results show that above a given threshold SNR ARQ protocols outperform network coding solution and we are able to accurately predict this threshold value. Furthermore, we proposed a new transmission protocol named HCVD (Horizontal Correction Vertical Detection) protocol, which is a new protocol combining network coding and ARQ protocol and which exhibits the best tradeoff BER performances/consumed power.

© 2014 National Institute of Information and Communicatio. In order to improve the throughput, robustness and resource utilization of relay network, we develop a new high-efficiency and stable two-way relay system with double antenna relay node, which employs combining Maximum Likelihood(ML) detection and Network Coding during access and broadcast stage respectively. It is not sensitive to link asymmetry compare with physical network coding(PNC), and can improve throughput by 50% compare with traditional three time slot relay network. This paper also employs and develops a novel automatic repeat request(ARQ) strategy to retransmit the corrupt packet, by using combination at the receiver, the users can recover the corrupt packet with negligible retransmission overhead. Numerical analysis and simulation results demonstrate that our proposed system can get a remarkable throughput improvement.

Prefix-assisted direct-sequence code-division multiple access (DS-CDMA) is a viable transmission technique for high-data-rate wireless broadband systems, capable of coping with highly dispersive channels at the uplink. Packet combining (PC) ARQ with an iterative block decision feedback equalization (IB-DFE) technique can be used to cope with errors. However, extracting the IB-DFE's packet error rate (PER) for MAC-layer simulations can be time consuming. Most works that model the DS-CDMA behavior with PC ARQ use simplified asymptotic PER models in the study of the system performance, which are not precise for low signal-to-noise ratios and for a low number of mobile terminals (MTs). In this paper, the MAC performance is modeled using a discrete-time Markov chain that relies on a PER model. As an example, this paper describes a PER analytical model for an uncoded prefix-assisted DS-CDMA system with PC ARQ that considers the following inputs: the number of MTs accessing the channel, the MTs' number of transmissions, and the channel realizations for a given bit energy over noise ratio. The results show that the model portrays with better accuracy the simulations' results, compared with an alternative asymptotic model.

For the wireless channel characteristics, this paper modifies the cumulative ARQ in order to improve the performance of the traditional cumulative ARQ. We put in sequence confirmed feedback to satisfy the demands of the new generation cellular mobile communication. An analysis model is developed for parameter manipulation in the proposed framework, where an important performance metrics, goodput, is investigated. Finally, the simulation results show that the performance of modified cumulative ARQ is better than traditional mechanism.

A novel cooperative automatic repeat request (ARQ) method with network coding is proposed for broadcast networks where single source node broadcasts multiple packets to multiple destinations. Upon a failed transmission, multiple relays cooperate with the source node at the retransmission phase, where network coding is used to combine multiple lost packets. A random access mechanism is employed where retransmission is done according to back-off counters. The proposed method employs the back-off mechanism to achieve space diversity by punishing the nodes which fail at previous retransmissions, and to reduce the number of retransmissions by giving priority to nodes having opportunity to employ network coding. The proposed method is compared with network coded ARQ without cooperation and traditional ARQ using Monte Carlo simulations for different channel settings. The effect of channel correlation is investigated where correlation is modeled as a finite-state Markov model. Simulation results show that the proposed use of cooperation and network coding for ARQ improves throughput performance when relay channels' conditions are better than the channels between source and destinations. It is also observed that, the proposed strategy exploits cooperation and space diversity to reduce the performance degradation due to correlation.

Despite being the most efficient automatic repeat request (ARQ) protocol, the selective-repeat ARQ (SR-ARQ) is previously thought to be infeasible in underwater acoustic communications owing to the half-duplex property of typical underwater acoustic modems. However, with the help of the juggling-like stop-and-wait (JSW) transmission scheme, it has now become feasible. In this paper, we evaluate the delivery delay (consisting of transmission and resequencing delays) of the SR-ARQ operating over the JSW scheme under the static assumption that the relative radial velocity between the transmitter and the receiver is zero, aiming to provide system designers with a valuable reference for delay evaluation under more general scenarios. We model the underwater acoustic channel as a two-state Discrete Time Markov Channel, and derive the closed-form expression for the delivery delay under heavy traffic situation. Unlike most analytical approaches for the delay analysis of SR-ARQ in terrestrial communications whose computational complexities grow exponentially with round-trip delay, our proposed analytical approach is immune to the round-trip delay. This also makes our approach suitable for terrestrial communications. To highlight the accuracy of our approach, we also provide comparisons between analytical and simulation results.

This paper investigates ARQ (Automatic Repeat request) designs for PNC (Physical-layer Network Coding) systems. We have previously found that, besides TWRC (Two-Way Relay Channel) operated on the principle of PNC, there are many other PNC building blocks--building blocks are simple small network structures that can be used to construct a large network. In some of these PNC building blocks, receivers can obtain side information through overhearing. Although such overheard information is not the target information that the receivers desire, the receivers can exploit the overheard information together with a network-coded packet received to obtain a desired native packet. This leads to throughput gain. Our previous study, however, assumed what is sent always get received. In practice, that is not the case. Error control is needed to ensure reliable communication. This paper focuses on the use of ARQ to ensure reliable PNC communication. The availability of overheard Information and its potential exploitation make the ARQ design of a network-coded system different from that of a non-network-coded system. In this paper, we lay out the fundamental considerations for such ARQ design: 1) We address how to track the stored coded packets and overheard packets to increase the chance of packet extraction, and derive the throughput gain achieved by tracking 2) We investigate two variations of PNC ARQ, coupled and non-coupled ARQs, and prove that non-coupled ARQ is more efficient; 3) We show how to optimize parameters in PNC ARQ--specifically the window size and ACK frequency--to minimize the throughput degradation caused by ACK feedback overhead and wasteful retransmissions due to lost ACK., Comment: 34 pages, 6 figures, 10 Tables,Technical Report

In this paper, we present hybrid ARQ techniques to improve the throughput performance in high speed packet transmission such as Internet or multimedia services. In order to evaluate the performance of the three different types of hybrid ARQ schemes, systemized link level simulations based on WWW traffic model are considered. In this paper, we also consider the simulated performance for an average link throughput and a normalized packet delay to compare the hybrid ARQ with link adaptation scheme in GPRS.

Equation based TCP-friendly rate control (TFRC) protocol has been proposed to support video streaming applications. In order to improve TFRC performance in wireless channels, the link level automatic repeat request (ARQ) scheme is usually deployed. However, ARQ cannot ensure strict delay guarantees, especially over multihop links. This paper introduces a theoretical model to deduce an equation for packet size adjustment in transport layer to minimize retransmission delay by taking into consideration the causative reasons inducing retransmission in link layer. An enhanced TFRC (ETFRC) scheme is proposed integrating TFRC with variable packet size policy. Simulation results demonstrate that higher goodput, lower packet loss rate (PLR), lower frame transmission delay and jitter with good fairness can be achieved by our proposed mechanism.

In this letter we investigate the packet delay statistics of a fully reliable selective repeat ARQ scheme by considering a discrete time Markov channel with non-instantaneous feedback and assigned round-trip delay m. Our focus is on studying the impact of the arrival process on the delay experienced by a packet. An exact model is introduced to represent the system constituted by the transmitter buffer, the m round-trip slots, and the channel state. By means of this model, we evaluate and discuss the delay statistics and we analyze the impact of the system parameters, in particular the packet arrival rate, on the delay statistics

A novel Automatic repeat ReQuest (ARQ) protocol called cooperative ARQ is presented in this letter, where a relay terminal is requested to retransmit an erroneously received packet, instead of the source terminal. The data link layer Packet Error Rate (PER) performance of cooperative ARQ is derived in correlated wireless channel. The results show that even though the relay-destination channel is worse than the source-destination channel, the new protocol outperforms the traditional one as long as the average SNR of the relay-destination channel is better than a certain threshold. It is also demonstrated that a second order diversity gain can be achieved with the cooperative ARQ protocol.

In this paper, an analytical framework is proposed for evaluating the quality of service (QoS) of TCP-friendly rate control protocol (TFRC) in hybrid wireless/wired networks. For the wireless network, a link-level truncated automatic repeat request (ARQ) scheme is deployed to reduce the packet losses visible to the transport layer protocol. Two discrete time Markov chains (DTMC) are introduced to analyze the network performance and the QoS of the TFRC protocol, in terms of wireless link utilization, flow throughput, packet loss rate, and probability of end-to-end delay exceeding a prescribed threshold. Extensive simulations are performed to verify the accuracy of the analytical results. It is concluded that the analytical results are useful for optimizing the system parameters, such as the interface buffer size and the maximum number of retransmissions of the truncated ARQ scheme. With the optimal parameters, wireless link utilization can be maximized, and the QoS requirements of multimedia applications can be statistically guaranteed

In this paper the packet delay statistics of a fully reliable selective repeat ARQ (SR ARQ) scheme is investigated. An N-state discrete time Markov channel model is used to describe the packet error process and the channel round trip delay is considered to be non zero, i.e., ACK/NACK messages are received at the transmitter m channel slots after the packet transmission started. The ARQ packet delay statistics is evaluated by means of an exact analysis by jointly tracking packet errors and channel state evolution. Furthermore, procedures to derive a Markov channel description of a Rayleigh fading process are discussed and the delay statistics obtained from the Markov analysis is compared with that estimated by simulation of the SR ARQ protocol over the actual fading process. The accuracy of the delay statistics obtained from the Markov Channel representation of the actual fading process is investigated by explicitly addressing the effect of the number of states considered in the Markov channel model and the impact of the Doppler frequency. Finally, besides giving a new analysis to obtain link layer statistics over N-state Markov channels, the paper provides important considerations on the adequacy of the widely used Markov modeling approach for the characterization of higher layer performance

In this paper, we develop a novel framework for analyzing radio link level performance for opportunistic scheduling with automatic repeat request (ARQ)-based error control in multi-rate wireless networks. The multi-rate transmission is assumed to be achieved through adaptive modulation and coding (AMC) to adjust the transmission rate according to the channel condition. The residual error effect due to each AMC setting is counteracted by means of a limited persistence ARQ protocol. The novelty of the proposed analytical framework lies in the fact that we are able to derive complete statistics (in terms of probability mass function) for both short-term and long-term performance measures such as system throughput, per-flow throughput, inter-success delay under both uncorrelated and correlated wireless channels. These performance measures can also be obtained in case of non-identical channels for different users. Analytical results are validated through simulations and the impacts of channel behavior on the different radio link level performance metrics are investigated.