Selective Repeat ARQ Research Articles

On modelling network coded ARQ-based channels

Network coding (NC) offers throughput improvements by algebraically combining multiple input packet streams which address one output port at an intermediate node. We present a practical implementation of NC with error control, namely stop-and-wait automatic repeat request (SW ARQ). We apply a modified NC scheme at an intermediate SW ARQ-based link to reduce ARQ control signals and then extend this to NC in a butterfly multicast network which adopts the selective repeat (SR) ARQ protocol as its error control scheme. We validate our throughput analysis using a relatively recent discrete-event simulator, SimEvents®. The results show a throughput advantage of at least 50%, particularly in the presence of high error rates. In the multicast SR ARQ network, NC-SR ARQ effectively doubles the throughput compared with the traditional scheme and increases the protocol’s ability to deal with propagation times that are long in comparison with the packet inter-arrival time.

Performance Evaluation of Some Dynamic ARQ Schemes for Multichannel Communication System

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.

A Markov Analysis of Selective Repeat ARQ with Variable Round Trip Time

Many papers analyze selective repeat automatic repeat request schemes by means of a Markov chain representation for the channel and, by extension, the whole transmission system. This Markov approach precisely characterizes the queueing behavior and the statistics of several delay terms. In the vast majority of the investigations, the round-trip time of the channel, which determines the instant of reception of the feedback from the receiver, is taken as a fixed value. This letter explores the relaxation of this assumption, still framing the system within a Markov chain. The main conclusion is that the impact of a variable round trip time on the delay statistics is rather limited. The used approach can be promptly applied to any similar analysis of retransmission-based error control systems.

Performance of TCP Over Free-Space Optical Atmospheric Turbulence Channels

This paper presents an analytical study of the performance of transmission control protocol (TCP) over free-space optical (FSO) turbulence channels when the automatic-repeat request, selective-repeat (ARQ-SR) scheme is employed. Different TCP versions, including Tahoe, Reno, and selective acknowledgement, are considered. In the TCP throughput analysis, a three-dimensional Markov model is used. In addition, to analyze the joint effect of ARQ-SR and FSO turbulence channels in terms of both TCP throughput and energy consumption, a newly defined joint throughput ? energy-efficiency parameter is analytically derived. In the numerical results, we discuss cross-layer design strategies for the selection of FSO system parameters and the ARQ-SR scheme in order to maximize the TCP throughput and to achieve the trade-off between the energy consumption and the throughput under various conditions of the FSO turbulence channel.

The Underwater Selective Repeat Error Control Protocol for Multiuser Acoustic Networks: Design and Parameter Optimization

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.

Performance Analysis of SR-ARQ Based on Geom/G/1/� Queue over Wireless Link

Selective-Repeat ARQ (Automatic Repeat reQuest) protocol is the most efficient error control technology in wireless because it allows the transmitter to retransmit only negatively acknowledges (NACK) packets. In this paper, by analyzing the transmission mechanism of SR-ARQ, the discrete-time Geom/G/1/ queue model is established sententiously based on equivalent delay under the condition that the numbers of packets entering the transmitter are assumed to be independent and identically distributed random variables. With the method of embedded Markov chain, the expression formulations of the packet mean waiting delay, system mean delay and channel utilization are explicitly obtained. And then, the sliding window length control model is built adaptively according to the change of transmission conditions. Furthermore, the influences of packet length, the successful transmission probability and packet arrival rate on system mean delay are analyzed by numerical simulation. The numerical simulation results show that the expression formulations are valid for SR-ARQ protocol.

Novel Design and Analysis of Aggregated ARQ Protocols for IEEE 802.11n Networks

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.

Optimizing Selective ARQ for H.264 Live Streaming: A Novel Method for Predicting Loss-Impact in Real Time

This work proposes a quality-oriented, real-time capable prioritization technique for media units of H.264/AVC video streams. The derivation of estimates is based on the analysis of the macroblock partitioning, the spatial extents of temporal dependencies, and the length and strength of prediction chains existing among macroblocks, thus incorporating the expected impact of error propagation. It is demonstrated how the prioritization scheme can be beneficially integrated into live streaming systems which are characterized by tight timing constraints, with the focus on content-aware selective automatic repeat request mechanisms. Additionally, it is shown how potentially limited feedback can be used to adapt the estimation process to leverage prediction preciseness. The approach is compared against existing techniques in terms of practicability and efficiency, and tested under independent and bursty loss conditions in a wired and a wireless test setup. Moreover, the performance is examined when low-latency and constant bitrate video settings are enforced by using x264's novel encoding feature periodic-intra-refresh. Results of both experiments and simulations indicate that the proposed technique outperforms all reference techniques in nearly all test cases, and that the video quality can be further improved by incorporating receiver feedback.

Tail asymptotic behaviour of resequencing buffer content for selective repeat ARQ

We consider resequencing buffer content at receiver’s side where the selective repeat automatic repeat request scheme is implemented for retransmission of erroneous packets in wireless networks. The error process of the wireless channel due to the fading is described by a discrete-time Markov chain. The study is carried out assuming that the round-trip time of packet over the channel is constant. The main concern in this paper is to characterize the tail asymptotics of the probability mass function of the resequencing buffer content at receiver’s side. Numerical results show that this approximation matches well with simulation.

Efficient ARQ Retransmission Schemes for Two-Way Relay Networks

In this paper1, we investigate different practical automatic repeat request (ARQ) retransmission protocols for twowaywireless relay networks based on network coding (NC). Theidea of NC is applied to increase the achievable throughput for the exchange of information between two terminals through one relay. Using NC, throughput efficiency is significantly improved due to the reduction of the number of retransmissions. Particularly, two improved NC-based ARQ schemes are designed based on go-back-N and selective-repeat (SR) protocols. The analysis of throughput efficiency is then carried out to find the best retransmission strategy for different scenarios. It is shown that the combination of improved NC-based SR ARQ scheme in the broadcast phase and the traditional SR ARQ scheme in themultiple access phase achieves the highest throughput efficiency compared to the other combinations of ARQ schemes. Finally, simulation results are provided to verify the theoretical analysis.

무선 환경에서 TCP 스퓨리어스 타임아웃 방지를 위한 SR-ARQ 재전송 지속성 관리 방안

To detect and recover packet losses over wireless links is very important in terms of reliability in packet transmission. Most wireless communication systems adopt an automatic repeat request (ARQ) protocol operating at link layer. However, it has been constantly addressed that the interaction not harmonized sufficiently between ARQ and TCP rather degrades TCP performance. In this paper, therefore, we propose an improved scheme from the aspect of the interaction with TCP loss recovery mechanism that can be applied to selective repeat ARQ (SR-ARQ) protocol and prove that the proposed scheme improves TCP performance significantly by OPNET simulations.

Design of MAC-defined aggregated ARQ schemes for IEEE 802.11n networks

Based on the IEEE 802.11n standard, frame aggregation is considered one of the major factors to improve system performance of wireless local area networks (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 schemes are proposed to consider the effect of frame aggregation for the enhancement of network throughput. An aggregated selective repeat ARQ (ASR-ARQ) algorithm is proposed, which incorporates the conventional selective repeat ARQ scheme with the consideration of frame aggregation. On the other hand, the aggregated hybrid ARQ (AH-ARQ) protocol is proposed to further enhance throughput performance by adopting the Reed-Solomon block code as the forward error correction (FEC) scheme. Novel analytical models based on the signal flow graph are established in order to realize the retransmission behaviors of both schemes. Simulations are conducted to validate and compare the proposed ARQ mechanisms with existing schemes based on service time distribution. Numerical results show that the proposed AH-ARQ protocol outperforms the other retransmission schemes owing to its effective utilization of FEC mechanism.

TCP/IP link layer error mitigation for MIMO wireless links

This paper investigates the effect of link-layer error mitigation support in MIMO wireless linking systems, and compares connection approaches between SISO and MIMO at different BER operating points substantiated by analysis of captured channels. In particular, this paper concentrates on a packet-based TDD approach, with a link-layer error mitigation scheme based on selective-repeat ARQ of segmented IP packets. Analytical expressions are derived for transfer efficiency over such a system, and simulation results presented to verify performance in terms of application delay experienced by users under various error conditions. This is repeated for SISO and for three alternative MIMO connection arrangements. Result show the degree of improvement available through the incorporation of link-layer error mitigation based upon the selective repetition of erroneous sub-IP packets, and in particular that presenting decomposed MIMO bit-pipes exhibiting diverse error conditions to the link layer, may be advantageous.

A Bandwidth Efficient Scheduling Framework for Non Real Time Applications in Wireless Networks

The key concern on the bandwidth allocation and scheduling for non real time traffic are the fulfillment of its minimum throughput requirement and improvement of bandwidth utilization with acceptable delay. This paper proposes a simple and efficient scheduling framework for allocating bandwidth to non real time polling service (nrtPS) users in IEEE 802.16 networks. In this framework, jointly selective repeat ARQ at the MAC layer and adaptive modulation and coding techniques at the physical are considered. Numerical simulations demonstrate that the proposed scheduling approach provides a graceful compromise between bandwidth utilization and packet delivery delay while maintaining the minimum throughput requirements of nrtPS applications. Thus proves the efficiency of the proposed framework. The simulation is done for unicast scenario.

Modeling and Analysis of Resequencing Delay in Selective Repeat Automatic Repeat Request

In selective repeat automatic repeat request (SRARQ) used by a transmitter-receiver pair, data packets correctly received by the receiver need to be delivered to its upper-layer protocol in the same order as they arrived at the transmitter from its upper-layer protocol . In this paper, we propose a novel discrete-time priority queueing network to model SR-ARQ, and study the performance of the resequencing buffer in terms of the mean packet resequencing delay when packets arrive to the network according to a Bernoulli process. Based on the stationary probability distribution of an embedded Markov chain, we derive an explicit expression for the mean packet resequencing delay. Numerical and simulation results of the mean resequencing delay are presented and some performance trends are discussed. This paper presents an analytic framework for accurately computing the mean packet resequencing delay caused by packet retransmission in data communication networks. The proposed discretetime priority queueing network model is expected to be used for performance analysis of ARQ protocols with a more general packet arrival process.

Selective automatic repeat quantum synchronous communication protocol based on quantum entanglement

From the classical selective repeat ARQ (Automatic Repeat-reQuest) protocol, a selective repeat ARQ quantum synchronous communication protocol in data link layer is presented by utilizing the intrinsic characteristics of quantum mechanics. The proposed protocol divides the link into the preparation and the send stages, where the message is sent via classical channel and the preparation and distribution of EPR (Einstein-Podolsky-Rosen) pairs are supposed to be accomplished at the preparation stage. The performances of several protocols in data link layer are compared and analyzed from the aspects of throughput and utilization ratio of the channel. It is shown that the proposed protocol enhances the maximum throughput and the utilization ratio of the channel effectively and improves the performance of the selective repeat ARQ protocol for date link layers. The proposed protocol is of great significance in military communications.

A New Scheme to Improve Overall TCP Throughput with Vertical Handover between 3G Cellular Packet Networks and Wireless LANs

One major difference between 3G cellular networks and Wireless LANs is in how packet losses are dealt with. 3G cellular networks employ selective repeat ARQ (SR-ARQ) whichmay result in packet-reordering due to local retransmissions. Wireless LANs employ stop-and-wait ARQ which may drop some packets in case the buffer overflows. While much work has been performed for TCP throughput enhancement with vertical handover between wired networks and wireless networks, little attention is paid to the vertical handover between two different wireless networks. It is expected for majority of new mobile devices to be able to connect to both 3G cellular networks and wireless LANs by being equipped with multiple wireless interfaces. If this is the case, on-going TCP transmission may move between 3G cellular networks and wireless LANs. In this paper, we propose a scheme to improve TCP throughput with vertical handoff between 3G cellular networks and wireless LANs. For this we develop an algorithm which differentiates packet-reordering from packet losses and congestion losses from wireless losses. Simulation of our algorithm using ns-2 shows significant increase in throughput as large as 80% compared to TCP-SACK. The proposed scheme is able to respond to the change of loss pattern and then improve the TCP throughput during handover.

Quality of service constrained throughput optimisation for joint adaptive transmission with automatic repeat request over block-fading channels

An optimisation framework for wireless link adaptation which maximises the system throughput subject to a packet-level quality of service (QoS) constraint is presented. The authors consider joint adaptive variation of the transmitted power level, transmission data rate and packet-error-rate (PER) at the physical layer to improve the throughput performance of the selective-repeat automatic repeat request (SR-ARQ) protocol over block-fading channels. Specifically, for discrete-rate coded M-QAM schemes, the authors present a power and rate adaptation algorithm that guarantees a target PER constraint. The proposed framework also facilitates optimising the throughput performance for delay constrained wireless applications, which imposes a limit on the number of retransmissions for the ARQ. In particular, a link adaptation scheme is presented, which guarantees a target packet-loss rate (PLR) when a truncated SR ARQ protocol at the data-link layer is employed. Numerical results indicate that the proposed adaptation schemes compared with other adaptive schemes noticeably enhance the system throughput. Also, in the case of truncated ARQ, the results illustrate a fundamental trade-off between the delay and PLR QoS metrics achieved at the maximum throughput performance.

Resequencing Analysis of Stop-and-Wait ARQ for Parallel Multichannel Communications

In this paper, we consider a multichannel data communication system in which the stop-and-wait automatic-repeat-request protocol for parallel channels with an in-sequence delivery guarantee (MSW-ARQ-inS) is used for error control. We evaluate the resequencing delay and the resequencing buffer occupancy, respectively. Under the assumption that all channels have the same transmission rate but possibly different time-invariant error rates, we derive the probability generating function of the resequencing buffer occupancy and the probability mass function of the resequencing delay. Then, by assuming the Gilbert-Elliott model for each channel, we extend our analysis to time-varying channels. Through examples, we compute the probability mass functions of the resequencing buffer occupancy and the resequencing delay for time-invariant channels. From numerical and simulation results, we analyze trends in the mean resequencing buffer occupancy and the mean resequencing delay as functions of system parameters. We expect that the modeling technique and analytical approach used in this paper can be applied to the performance evaluation of other ARQ protocols (e.g., the selective-repeat ARQ) over multiple time-varying channels.

A flexible resource allocation and scheduling framework for non-real-time polling service in IEEE 802.16 networks

This paper proposes an efficient yet simple design framework for achieving flexible resource allocation and packet scheduling for non-real-time polling service (nrtPS) traffic in IEEE 802.16 networks. By jointly considering the selective automatic repeat request mechanism at the media access control layer as well as the adaptive modulation and coding technique at the physical layer, the proposed framework enables a graceful tradeoff between resource utilization and packet delivery delay while maintaining the minimum throughput requirements of nrtPS applications. An analytical model is developed for parameter manipulation in the proposed framework, where some important performance metrics, such as inter-service time, delivery delay, goodput, and resource utilization, are investigated for performance evaluation. Simulation results are given to demonstrate the efficiency of the proposed framework and verify the accuracy of the analytical model.