Selective Repeat Research Articles

Assessment of Communication Resource Allocation by the Transmission Control Protocol for the Target Virtual Connection under Competitive Conditions

The mathematical framework presented in this article focuses on the controlled-transmission protocol’s asynchronous process of bandwidth allocation for the target virtual connection implemented under competition for communication resources. The studied process is formalized as a two-dimensional discrete Markovian chain, taking into account the distributions of queue lengths of TCP data fragments from competing client nodes. Such a chain describes the dynamics of filling the stack of transmitted but unacknowledged data fragments of the investigated end device. Distributions of the chain states were found for various ratios of the target virtual-connection bandwidth, transmission-protocol parameters, and communication-channel characteristics. Analytical dependencies for computing the performance of the target virtual connection for different operating modes were obtained. The results of experiments conducted based on the obtained analytical constructions showed that the performance of the virtual connection with a selective repeat mode is mainly determined by the data-loss intensity, the queue size distribution in transit nodes, and the ratio between the protocol window size and the route length.

A Novel Covert Channel for IEEE 802.11 Networks Utilizing MAC Address Randomization

Vendors implement the MAC address randomization technique to prevent IEEE 802.11 client station devices from being tracked. Although it conceals device identity, it cannot hide its occurring data transmission. This paper presents a novel covert channel that leverages the MAC address randomization technique to create a covert channel to hide data transmission inside IEEE 802.11 networks. The secret data are a disposable random MAC address generated by the IEEE 802.11 station as part of the probe request frame while scanning the network. The paper presents the concept of the covert channel, its implementation, and performance metrics. The study covers diverse scenarios, including the adaptation of the modified Selective Repeat ARQ protocol to alleviate the impact of the number of client stations and their offered loads on the covert channel. The results show that with the appropriate parameter selections, we can adapt the covert channel to produce excellent throughput, efficiency, delay, and jitter according to the environment in which it is installed.

Effect of Sliding Windows Technique on the Performance of TCP/IP Networks

AbstractTwo basic strategies have developed by network designers to deal including errors. by adding extra information to data before sending. such approach is to comprise sufficient extra information to make destination to infer what the sent data should be, or it possible to add only sufficient extra information to let destination to infer that errors have been occurred, however not which error then have it ask re-send defected data. Previous strategy utilizes errors correcting mechanism and latter uses errors detecting mechanism. Utilize of errors correcting mechanism is named as Forward Error Correction (FEC). In this thesis, sliding window has been implemented over Multi-Protocol Label Switching (MPLS). Therefore, MPLS send data from one node to other node on network depend on short path labels instead of logical addresses in network layer, in addition to that MPLS is connection oriented compared to IP network. Finally, we have study and analyze sliding technique performance over MPLS from delay, throughput and packet loss point of view. It is show that go back N has belter performance compared to selective repeat in term of throughput.

Teletraffic analysis and simulation on FSO systems: the traffic generators approach

Free Space Optical Communications (FSO) has become an interesting topic to researchers in recent years since the amount of data generated by devices is growing, and it is necessary to use data links that support high bandwidth to transmit them from one device to another. This technology is used to establish not only terrestrial links but also space links.A CubeSat satellite is generally deployed in the Low Earth Orbit (LEO) region. To maintain the altitude, the satellite must have a high orbital speed. For that reason, the time to transmit data between a particular ground station and the CubeSat satellite is limited. On the other hand, the volume, mass, and energy storage capacity are restricted in a CubeSat. The greater the bandwidth capacity of radio frequency links, the greater the demand for volume, mass, and energy they require. For that reason, to transmit a significant amount of data, traditional radio frequency links are not suitable and are becoming replaced by FSO as technology improves.Despite research in physical layer technologies on FSO (modulation schemes, error mitigation techniques, pointing and tracking systems), there is very little research in the literature about data link layer protocols for FSO. Secondly, there is little research to measure the data traffic demand on CubeSat satellites so that a certain data link layer protocol can be selected or adapted to be implemented in an FSO system.This paper presents research to address the issue of teletraffic through the use of traffic generators. The result is the design and development of a traffic generator for a discrete event simulator that will later be used to observe the behavior and to measure the performance of the Selective Repeat ARQ protocol in a simulated satellite FSO link, in order to propose improvements to adapt the protocol to this scenario.

SDN-Driven Internet of Health Things: A Novel Adaptive Switching Technique for Hospital Healthcare Monitoring System

In the last decent, the number of Internet of Things (IoT) health-based paradigm reached to a huge number of users, services, and applications across different disciplines. Thus, hundreds of wireless devices seem to be distrusted over a limited or small area. To provide a more efficient network, the software-defined network (SDN) thought to be a good candidate to deal with these huge number of wireless users. In this work, after a novel SDN algorithm is proposed for the hospital environment, it is also designed and integrated into an Internet of Health Things (IoHT) paradigm. The novel algorithm called adaptive switching (AS) is proposed as a novel adaptive access strategy based on adaptively hoping among existing Go-Back-N and Selective Repeat techniques. Finally, the throughput performance of the proposed AS method is compared with the performances of traditional Go-Back-N and Selective Repeat ARQ methods using the developed MATLAB simulation. For this, an optimal P error rate that the network should prefer to switch either from Go-Back-N to Selective Repeat or from Selective Repeat to Go-Back-N method to maximize the network throughput performance is determined. The evaluated results are also confirmed by theoretical calculation results using well-known Mathis throughput formula. It is observed from the simulation results that the best throughput performance can be evaluated, when AS switches to Go-Back-N if the P error is less than 3.5% and it switches back to Selective Repeat when the P error is greater than 3.5%. By this way, it is also observed that the throughput always has its best possible results for all P error rates and up to 37.52% throughput improvement is provided by the use of novel proposed adaptive switching (AS) algorithm.

A cooperative protocol for pervasive underwater acoustic networks

The novel Underwater Wireless Sensor Network (UWSN) can contribute to monitor and explore aquatic environments. But, communicating in these environments is still hard and has many challenges. For example, optical and electromagnetic waves deteriorate from high-attenuation. Moreover, acoustic communication has a large packet error rate and low throughput. A large number of solutions to improve aquatic communication refers to routing protocols, medium access control protocols, and designing acoustic modems. Cooperative communication explores the broadcast nature of wireless transmission and enhances its performance. However, cooperative communication has not been fully explored in UWSNs. In this work, we present COPPER, a Cooperative Protocol for Pervasive Underwater Acoustic Networks. COPPER considers LLC and MAC sub-layers and operates synchronously or asynchronously over Time Division Multiple Access using a selective repeat ARQ scheme. COPPER exploits the broadcast nature of wireless communication and, sensor nodes that are idle can operate as a relay, enhancing communication by space diversity. Simulation results show that COPPER improves network performance. For example, the network goodput improves by 17% and the packet error rate decreases by 65%.

TCP Performance Over Satellite-Based Hybrid FSO/RF Vehicular Networks: Modeling and Analysis

Recent years have witnessed a growing interest in Internet access from space assisted by low earth orbit (LEO) satellite networks. In the domain of the last-mile access for the Internet of Vehicles (IoV), hybrid free-space optical (FSO)/radio-frequency (RF) communication has recently attracted worldwide research efforts. While the transmission control protocol (TCP) is the most widely deployed transport protocol on the Internet, its performance in the error-prone environment of LEO satellite-assisted hybrid FSO/RF vehicular networks is not well understood. This paper develops a comprehensive analytical model based on the cross-layer approach for TCP performance, considering the FSO and RF satellite fading channels, modeled by the Gamma-Gamma and Nakagami- m distributions, respectively. The error-control solutions, including the Reed-Solomon (RS) code and Selective repeat automatic repeat request (SR-ARQ), are also employed. Numerical results quantitatively demonstrate the impact of transmission errors at last-mile links and different parameters/settings of error-control solutions on the TCP performance. The paper also supports the selection of proper TCP variants for the considered networks.

Adaptive Causal Network Coding With Feedback

We propose a novel adaptive and causal random linear network coding (AC-RLNC) algorithm with forward error correction (FEC) for a point-to-point communication channel with delayed feedback. AC-RLNC is adaptive to the channel condition, that the algorithm estimates, and is causal, as coding depends on the particular erasure realizations, as reflected in the feedback acknowledgments. Specifically, the proposed model can learn the erasure pattern of the channel via feedback acknowledgments, and adaptively adjust its retransmission rates using a priori and posteriori algorithms. By those adjustments, AC-RLNC achieves the desired delay and throughput, and enables transmission with zero error probability. We upper bound the throughput and the mean and maximum in order delivery delay of AC-RLNC, and prove that for the point to point communication channel in the non-asymptotic regime the proposed code may achieve more than 90% of the channel capacity. To upper bound the throughput we utilize the minimum Bhattacharyya distance for the AC-RLNC code. We validate those results via simulations. We contrast the performance of AC-RLNC with the one of selective repeat (SR)-ARQ, which is causal but not adaptive, and is a posteriori. Via a study on experimentally obtained commercial traces, we demonstrate that a protocol based on AC-RLNC can, vis-a-vis SR-ARQ, double the throughput gains, and triple the gain in terms of mean in order delivery delay when the channel is bursty. Furthermore, the difference between the maximum and mean in order delivery delay is much smaller than that of SR-ARQ. Closing the delay gap along with boosting the throughput is very promising for enabling ultra-reliable low-latency communications (URLLC) applications.

5G-Enabled Fault Detection and Diagnostics: How Do We Achieve Efficiency?

The 5th-generation wireless networks (5G) technologies and mobile edge computing (MEC) provide great promises of enabling new capabilities for the industrial Internet of Things. However, the solutions enabled by the 5G ultra-reliable low-latency communication (URLLC) paradigm come with challenges, where URLLC alone does not necessarily guarantee the efficient execution of time-critical fault detection and diagnostics (FDD) applications. Based on the Tennessee Eastman Process model, we propose the concept of the communication-edge-computing (CEC) loop and a system model for evaluating the efficiency of FDD applications. We then formulate an optimization problem for achieving the defined CEC efficiency and discuss some typical solutions to the generic CEC-based FDD services, and propose a new uplink-based communication protocol called "ReFlexUp". From the performance analysis and numerical results, the proposed ReFlexUp protocol shows its effectiveness compared to the typical protocols such as Selective Repeat ARQ, HARQ, and "Occupy CoW" in terms of the key metrics such as latency, reliability, and efficiency. These results are further convinced from the mmWave-based simulations in a typical 5G MEC-based implementation.

Adaptive Causal Network Coding with Feedback for Multipath Multi-hop Communications

We propose a novel multipath multi-hop adaptive and causal random linear network coding (AC-RLNC) algorithm with forward error correction. This algorithm generalizes our joint optimization coding solution for point-to-point communication with delayed feedback. AC-RLNC is adaptive to the estimated channel condition, and is causal, as the coding adjusts the retransmission rates using a priori and posteriori algorithms. In the multipath network, to achieve the desired throughput and delay, we propose to incorporate an adaptive packet allocation algorithm for retransmission, across the available resources of the paths. This approach is based on a discrete water filling algorithm, i.e., bit-filling, but, with two desired objectives, maximize throughput and minimize the delay. In the multipath multi-hop setting, we propose a new decentralized balancing optimization algorithm. This balancing algorithm minimizes the throughput degradation, caused by the variations in the channel quality of the paths at each hop. Furthermore, to increase the efficiency, in terms of the desired objectives, we propose a new selective recoding method at the intermediate nodes. We derive bounds on the throughput and the mean and maximum in-order delivery delay of AC-RLNC, both in the multipath and multipath multi-hop case. In the multipath case, we prove that in the non-asymptotic regime, the suggested code may achieve more than 90% of the channel capacity with zero error probability under mean and maximum in-order delay constraints, namely a mean delay smaller than three times the optimal genie-aided one and a maximum delay within eight times the optimum. In the multipath multi-hop case, the balancing procedure is proven to be optimal with regards to the achieved rate. Through simulations, we demonstrate that the performance of our adaptive and causal approach, compared to selective repeat (SR)-ARQ protocol, is capable of gains up to a factor two in throughput and a factor of more than three in mean delay and eight in maximum delay. The improvements on the throughput delay trade-off are also shown to be significant with regards to the previously developed singlepath AC-RLNC solution.

Discovery and Structure-Based Optimization of Potent and Selective WD Repeat Domain 5 (WDR5) Inhibitors Containing a Dihydroisoquinolinone Bicyclic Core.

WD repeat domain 5 (WDR5) is a member of the WD40-repeat protein family that plays a critical role in multiple chromatin-centric processes. Overexpression of WDR5 correlates with a poor clinical outcome in many human cancers, and WDR5 itself has emerged as an attractive target for therapy. Most drug-discovery efforts center on the WIN site of WDR5 that is responsible for the recruitment of WDR5 to chromatin. Here, we describe discovery of a novel WDR5 WIN site antagonists containing a dihydroisoquinolinone bicyclic core using a structure-based design. These compounds exhibit picomolar binding affinity and selective concentration-dependent antiproliferative activities in sensitive MLL-fusion cell lines. Furthermore, these WDR5 WIN site binders inhibit proliferation in MYC-driven cancer cells and reduce MYC recruitment to chromatin at MYC/WDR5 co-bound genes. Thus, these molecules are useful probes to study the implication of WDR5 inhibition in cancers and serve as a potential starting point toward the discovery of anti-WDR5 therapeutics.

Backbone-Assisted Wireless Local Area Network

This article presents a cross-layer design of backbone-assisted wireless local area network (WLAN) for dense WLAN deployment. The popularity of 802.11-based WLANs leads to dense WLAN deployment in geographically limited space, including dense access points (AP) and dense users. With dense APs, an AP could overhear packets destined for other APs. Backbone-assisted WLAN is a new system architecture where cooperative APs share the overheard packets through a backbone network, thereby reducing packet retransmission and improving system throughput. Conventional WLAN, such as Wi-Fi, uses Stop-and-Wait ARQ. This article argues that Stop-and-Wait does not work well with backbone-assisted WLAN because of large backbone delays. We first show that with a variant of Selective Repeat ARQ tailored for backbone-assisted WLAN, a single-user backbone-assisted WLAN system can achieve substantial throughput improvement over that with Stop-and-Wait ARQ. Then, we put forth a new system architecture targeted for dense users, referred to as network-coded backbone-assisted WLAN, in which multiple users are allowed to transmit simultaneously. A distinguishing feature of this system is the joint use of physical-layer network-coding (PNC) decoding and multiuser decoding (MUD) in multipacket reception. This article is the first attempt to design an ARQ for multiuser backbone-assisted WLAN. Our overall system design solves a PNC sequence obfuscation problem and addresses long packet latency in Selective Repeat ARQ. Experiments on our software-defined radio prototype indicate that network-coded Ethernet-backbone-assisted WLAN can achieve high system throughput and low packet latency. Specifically, the system throughput can outperform an MUD-only multiuser WLAN and a single-user WLAN by 60 and 100 percent, respectively. Overall, we believe that network-coded backbone-assisted WLAN is a viable solution for boosting throughput and reducing latency in dense WLAN environments.

Overload Control with Hybrid SIP Signaling - Using Smart Reliability and Priority Queuing Strategies

Session Initiation Protocol is an IP based application level signaling protocol. SIP employs request retransmission for enabling reliability over UDP transport. This research work proposes a Hybrid SIP System that integrates the congestion control techniques from the proposed Smart Reliable SIP and Overload control using Advanced Smart Priority (ASP) Queuing Strategy. The proposed system reduces retransmissions and queuing delays in SIP servers. Smart Reliable SIP (SRSIP) implements the modified Selective Repeat ARQ protocol for enabling reliability of SIP requests without violating the SIP core functionality. SRSIP reduces the number of retransmissions. ASP Queuing Strategy prioritizes the SIP requests based on the retransmissions. The proposed system reduces the queuing delays for request processing at the downstream server and the retransmissions over the network. The Hybrid models integrates the features of both Smart Reliable SIP and ASP queuing strategy resulting in a system with almost zero retransmissions and reduced queuing delay for request processing.

Channel Constrained Multiple Selective Retransmissions for OFDM System: BER and Throughput Analysis

Hybrid automatic repeat request (HARQ) retransmission is an effective method to combat time-variant channel fading. Conventional HARQ methods initiate retransmission of failed packet without exploiting channel knowledge. When a packet fails, retransmission of data corresponding to high gain sub-carriers of an orthogonal frequency division multiplexing (OFDM) modulation is not necessary and deteriorates the throughput of the communication system. In this paper, we propose accumulated channel norm constrained selective retransmission (CNSR) at physical layer (PHY) in conjunction with HARQ method, which enhances throughput of the transceiver without compromising latency. When a packet fails, medium access control (MAC) layer requests retransmission of the failed packet. The proposed CNSR method initiates retransmission of data at PHY layer transmitted over low signal-to-noise ratio sub-carriers using outdated channel information. The transceiver pair continues retransmission of the failed packet until target channel norm of the sub-carriers is achieved or maximum number of retransmissions are completed. We maximize throughput by optimizing threshold on channel norm for OFDM modulation. We also present an upper bound on bit error rate and throughput analysis of the proposed method. The proposed method achieves higher throughput as compared with the existing Chase combining with selective repeat and conventional Chase combining schemes with and without forward error correction codes.

Energy Efficiency, Spectral Efficiency and Delay Analysis for Selective ARQ Multichannel Systems

In this paper, we develop selective retransmission schemes for multiple-channel systems. The proposed schemes are selective automatic repeat request with fixed bandwidth, selective chase combining with fixed bandwidth, limited selective chase combining with fixed bandwidth and selective automatic repeat request with variable bandwidth. The main objective of the proposed schemes is to use the available power and bandwidth budget effectively along with selective retransmission to deliver the required data successfully within a limited number of transmissions. To investigate the performance of each scheme, we first analyze and derive closed-form expressions for the average spectral efficiency (SE), energy efficiency (EE) and delay for each scheme. Then, we compare the EE, SE and delay performance of each scheme versus different system parameters through numerical results.

Reed Solomon Erasure Coding for the Optimization of Network Reliability and Energy Efficiency in Wireless Sensor Networks

This Network error correction (NEC) helps to correct errors of a communication network by using the concept of network coding [1] and provides an alternative to the traditional link-by-link error correction. NEC is widely used in sensor networks and in video network broadcasting, where the network suffers from delay and energy constraints. This paper aims to design an Automatic Repeat Request (ARQ)based RS-erasure code to correct the errors/ erasures encountered in the data packets due to the random errors and unreliable network links. The proposed protocol tries to combine the RS-Erasure code and Selective Repeat (SR based) retransmission scheme to achieve the higher network reliability and energy efficiency in wireless sensor networks. In this scheme the code rate of a given message block is calculated dynamically depending upon the error rate of the link to minimize the total transmission efforts. The performance of the proposed technique is compared with some existing techniques like SR-ARQ, SRTP [11] and CRBT [24] on the basis of Total transmissions required for end to end reliable data delivery, energy consumption by the network nodes, transmission delay and the network-throughput.

Repeat staging laparoscopy for gastric cancer after preoperative therapy.

Staging laparoscopy is recommended before preoperative therapy in patients with locoregional gastric cancer, but yield of repeated diagnostic laparoscopy at the time of resection is unknown. Retrospective review of a prospective database of patients with gastric adenocarcinoma (1994-2016) who had negative staging laparoscopy followed by preoperative therapy and subsequent attempted resection. Primary outcome was positive exploration (peritoneal or unresectable disease) at the time of resection. Multivariable logistic regression identified factors associated with positive exploration. Of the 451 patients with attempted resection, 54 (12.0%) had positive explorations, including 48 with peritoneal disease. Patients with positive explorations were more likely to be female and have poorly differentiated tumors, linitis features, and signet-ring morphology. There was no significant difference by exploration results in age, race, clinical stage, or delayed definitive surgery. Positive explorations were independently associated with poor differentiation (OR 4.6, 95%CI 1.4-15.3; P = 0.01) and linitis (OR 4.2, 95%CI 1.9-9.2; P < 0.001). Positive explorations were seen in 14.0% of patients with poor differentiation, 36.6% of patients with linitis, and 5.8% of patients with neither linitis nor poor differentiation. Despite negative pretreatment laparoscopy, post-treatment repeat laparoscopy may prevent non-therapeutic laparotomies. At a minimum, we recommend selective repeat laparoscopy for patients with linitis features.

Modeling Reliable M2M/IoT Traffic Over Random Access Satellite Links in Non-Saturated Conditions

Nowadays, Machine-to-Machine and Internet of Things traffic sources puts the terrestrial networks under great pressure. While 5G is still on its way, satellites are used to deliver a fraction of such an enormous traffic rate. In this work, we investigate the use of the Constrained Application Protocol (CoAP) to reliably deliver Machine-to-Machine and Internet of Things traffic in a push fashion, which also implements a Selective Repeat Automatic Repeat reQuest and a sender-based variant of the TCP Friendly Rate Control protocol. We aim at providing an analytical model to evaluate the working point of the system in non-saturated conditions as a function of the MAC parameters in use, when such a closed-loop congestion control mechanism is in use over a random access satellite channel. The proposed analytical model is then validated against simulation results, showing a good precision.

Caterpillar RLNC With Feedback (CRLNC-FB): Reducing Delay in Selective Repeat ARQ Through Coding

Wireless networks typically employ some form of forward error correction (FEC) coding and some automatic repeat request (ARQ) protocol to ensure reliable data transmission over lossy channels. We propose to integrate FEC and ARQ in the context of random linear network coding (RLNC). In particular, we develop Caterpillar RLNC with feedback (CRLNC-FB), an RLNC approach with a finite sliding packet transmission window in conjunction with feedback-based selective repeat ARQ. CRLNC-FB employs a novel RLNC decoding method based on a band-form of Gaussian elimination. In response to lost packets, CRLNC-FB retransmits lost packets in systematic (uncoded) form to aid fast in-order packet delivery at the receiver. Extensive performance evaluations indicate that CRLNC-FB gives higher throughput-delay performance than the preceding RLNC approaches with feedback. In particular, CRLNC-FB with its sliding window achieves lower delays than block-based RLNC. Also, the retransmission of uncoded source packets in CRLNC-FB contributes to a significantly higher throughput-delay performance than loss recovery through coded packets interspersed among future source packets at a prescribed code rate.

Energy Efficiency Investigation for the MB-OFDM UWB Cross-Layer Design

Green communication has become the main concern of many researchers according to the quick evolution of wireless communication applications. For this, in this correspondence we develop a cross-layer framework based on the joint association between Modulation and Coding Scheme together with truncated Selective Repeat Hybrid Automatic Repeat Request type I to examine the global energy consumption per bit of Multiband Orthogonal Frequency Division Multiplexing Ultra Wideband (MB-OFDM UWB) systems. Indeed, we examine a theoretical analysis based on throughput performance investigation when mode selection is performed which is dynamically selected following the Channel State Information. Next, we prove that cross-layer design outperforms the mode selection behavior in terms of outage probability. Then, based on the features of cross-layer MB-OFDM UWB (MB-UWB) design a theoretical framework is derived in terms of Packet Error Rate and overall energy expenditure per bit. Specifically, the closed form relation of energy per bit is determined by exploiting the proprieties of the two link adaptation tools. Correspondingly, since the purpose behind cross-layer design adoption into MB-UWB system is EE improvement, we have compared the impact of different M-QAM modulations into energy consumption per useful bit at various range of distances. The obtained results reveal that cross-layer design is a powerful solution in terms of EE enhancement.