Retransmission Attempts Research Articles

Design, Simulation, and Performance Evaluation of Reactive and Proactive Ad-Hoc Routing Protocols

The primary goal of this study is to investigate and evaluate the performance of wireless Ad-Hoc routing protocols using the OPNET simulation tool, as well as to recommend the most effective routing strategies for the wireless mesh environment. Investigations have been testified to analyze the performance of the reactive and proactive Ad-Hoc routing protocols in different scenarios. Application and wireless metrics were configured that were used to test and evaluate the performance of routing protocols. The application metric includes web browsing metrics such as HTTP page response time, voice and video metrics such as end-to-end delay, and delay variation. The wireless network metrics include wireless media access delay, data dropped, wireless load, wireless retransmission attempts, and Packet Delivery Ratio. The simulation results show that the AODV overcome DSR and OLSR in terms of PDR (76%), wireless load (22.692 Mbps), voice delay variation (102.685 ms), HTTP page response time (15.317 sec), voice and video packet end-to-end delay (206.527 and 25.294 ms), wireless media access delay (90.150 ms), data dropped (10.003 Mbps), wireless load (22.692 Mbps), and wireless retransmission attempts (0.392 packets).

Mobility Based Routing Protocol Performance Oriented Comparative Analysis in the ADHOC Networks FANET, MANET and VANET using OPNET Modeler for FTP and Web Applications

In FANET (Flying ad-hoc network), VANET (Vehicular ad-hoc network), MANET (Mobile Ad-hoc Network), the phenomena routing happens without the support of infrastructure. To accomplish these tasks, the nodes used to act as both router and the host. The design of routing protocol is very complex and challenging, because of the unpredictable varying topologies in these ad-hoc networks. In this paper the performance of the three ad-hoc networks are analysed in terms of its response from the network parameters such as delay, throughput, media access delay, load, retransmission attempts network loads and throughputs. The simulation is carried out in riverbed modeler academic edition 17.5. In this paper, based on simulation results, the routing protocols are categorized in terms of performance for the network parameters. Also, the performance of routing protocols is analysed based on its individual performance on the network parameters.

Swift HARQ Based on Machine Learning for Latency Minimization in URLLC

Ultra-reliable low-latency communication (URLLC) has been introduced in the 5th Generation (5G) radios for mission-critical applications that demand strict reliability and latency traffic to guarantee the rapid delivery of short packets (up to 1 ms) with a success probability rate of 99.999%. The challenging reliability and latency requirements of URLLC have significant impact on the air-interface design, especially on the Hybrid Automatic Repeat reQuest (HARQ) mechanism. This study focuses on satisfying link latency requirements by reducing the delay that arises in the presence of the HARQ operation. To this end, we propose a Swift HARQ protocol empowered by machine learning techniques to estimate the decodability of a packet early enough within its maximum number of allowable retransmission attempts. This can allow the transmitter to react faster by dropping the non-decodable packets, or activating the repetition mode where parts of the HARQ feedback can be omitted. As shown through system-level simulations, the proposed model achieves a delay reduction of more than 50% compared to the traditional HARQ, and increases the system throughput by up to 40% when multiple HARQ retransmissions are required.

Energy Minimization of Mobile Edge Computing Networks With HARQ in the Finite Blocklength Regime

We consider a mobile edge computing (MEC) network supporting low-latency, critical offloading workloads. The task offloading from the user to the server is operated under a truncated Hybrid Automatic Repeat reQuest (HARQ) process, i.e., we consider finite retransmission attempts. Both the HARQ type-I and type-II schemes are studied. For each scheme, we first characterize the total error probability and the total energy cost, while the impact of finite blocklength (FBL) on the stochastic retransmission behavior is considered. Following the characterizations, we are interested in optimal frameworks for each considered HARQ type, where the number of potential retransmission attempts is optimized together with the duration of each transmission, while the CPU frequency at the edge node is adjusted via voltage scaling. The objective is to minimize the total energy cost with error probability threshold. We show that the resulting stochastic optimization problems can be solved by means of convex optimization. We furthermore demonstrate that sharp minima exist among the energy consumption, underlying the importance of near-optimal parameter choice in the studied scenarios. Our results underline the importance of trading off communication and computational characteristics in delay-critical MEC setups with FBL codes.

A Multicast-based MAC Protocol for Improving Data Transmission Efficiency in Industrial WSNs.

In industrial WSNs, attaining the desired level of data transmission efficiency is highly challenging not only for a frequently changing network topology but also for a short data acquisition cycle time. A short data acquisition time often restrains a sensor MAC protocol to incorporate an effective data packet salvaging technique. Therefore, we propose a data transmission technique in which a sending node multicasts data packets to all candidate parents including its primary parent. As a result, the necessity of data retransmission attempts is totally avoided, which greatly improves the data transmission efficiency in industrial WSNs. By simulation experiments, we have shown that the proposed multicast-based MAC protocol surpasses all the competing MAC protocols regarding the successful data packet delivery and power saving with a significant margin

Comparative Study of Different FANET 802.11 Wireless Protocols with Different Data Loads

IEEE 802.11 based Wireless Local Area Networks (WLANs) are becoming popular in home, enterprise and public access areas primarily due to their low cost, simplicity of installation and high data rates. While WLANs continue to be predominantly data centric, there is growing interest in using WLANs for voice and text data especially in enterprise markets. In this paper, a comprehensive analysis comparison to measure the delay, throughput packet loss and retransmission attempts was done to different scenarios using different trending wireless protocols such as 802.11n (2.4GHz, 5GHz), 802.11g, 802.11b, 802.11a while transferring low and high data load in FANET, with two major routing protocols AODV, and OLSR. As concluded in the result, recent wireless technology 802.11n with frequency band such of 2.4GHz can give better performance as they transfer higher data rates with longer distances and frequency band of 5GHz with higher data rate and less distance than 2.4GHz.

HARQ Optimization for PDCP Duplication-Based 5G URLLC Dual Connectivity

Packet duplication (PD) with dual connectivity (DC) was newly introduced in the 5G New Radio (NR) specifications to meet the stringent ultra reliable low latency communication (URLLC) requirements. PD technology uses duplicated packets in the packet data convergence protocol (PDCP) layer that are transmitted via two different access nodes (ANs) to the user equipment (UE) in order to enhance the reliability performance. However, PD can result in unnecessary retransmissions in the lower layers since the hybrid automatic retransmission request (HARQ) operation is unaware of the transmission success achieved through the alternate DC link to the UE. To overcome this issue, in this paper, a novel duplication-aware retransmission optimization (DRO) scheme is proposed to reduce the resource usage induced by unnecessary HARQ retransmissions. The proposed DRO scheme can minimize the average channel use while satisfying the URLLC requirements. The proposed DRO scheme derives the optimal HARQ retransmission attempts for different ANs by solving a nonlinear integer programming (NLIP) problem. The performance of the proposed DRO scheme was evaluated using MATLAB simulation and is compared to the existing 5G HARQ support schemes. The simulations results show that the proposed DRO scheme can provide a 14.71% and 15.11% reduced average channel use gain compared to the selective data duplication upon failure (SDUF) scheme and latency-aware dynamic multi-connectivity algorithm (LADMA) scheme, respectively, which are the existing 5G PD schemes that use HARQ.

Hybrid Architectural Network Implementation to Realize a Fire Evacuation Path with 2.4 GHz Zigbee and LoRa

The Internet of Things (IoT) is playing a significant role in realizing real monitoring. In fire safety and evacuation, early fire event detection using IoT-enabled sensors may help to control and minimize further consequences of the fire accident. In this study, we propose a hybrid architecture based on 2.4 GHz Zigbee and long-range (LoRa) for real-time fire detection, monitoring, and assisting in the safe evacuation of the building. The architecture comprises five different components, namely: end device, evacuation path display controller, safety operation controller, vision node, and gateway. The end device and vision node provide real-time sensory data and visuals that provide details of fire occurrence. The evacuation path display controller and the safety operation controller based on the 2.4 GHz Zigbee receive data from the end device and make the decision accordingly. In addition, a Zigbee simulation is performed on the OPNET simulator to analyze the network parameters such as throughput, retransmission attempts, medium access (MAC) queue size and queue delay, and packet delivery ratio (PDR). The evaluation metrics of link budget and ToA of LoRa are also calculated by varying the code rate and spreading factor. To realize the proposed architecture, customization of hardware is carried out with the development of hardware prototypes. Dijkstra’s shortest path algorithm is implemented in the evacuation path display controller to provide the shortest evacuation path during a fire incident. The hardware of the system is implemented in real-time, and the system provides real-time sensor data along with the evacuation path.

Zigbee and Long-Range Architecture Based Monitoring System for Oil Pipeline Monitoring with the Internet of Things

Oil pipeline monitoring is having a significant role in minimizing the impact on the environment and humans during pipeline accidents. The real-time monitoring of oil pipelines empowers the authorities to have continuous supervision of the oil pipeline. The Internet of Things (IoT) provides an opportunity for realizing the real-time monitoring system by deploying the IoT-enabled end devices on the oil pipeline. In this study, we propose a hybrid architecture based on 2.4 GHz-based Zigbee and LoRa communication for oil pipeline monitoring. Moreover, customized end devices and LoRa based gateway are designed and implemented for sensing the critical parameters of an oil pipeline. Here, we have performed the simulation of ZigBee communication on the OPNET simulator for evaluating the parameters such as packet delivery ratio (PDR), retransmission attempts, throughput, medium access (MAC) queue size, and queue delay. Furthermore, the distinct evaluation metrics of LoRa such as bit rate, link budget, and receiver sensitivity are also included. Finally, a real-time experiment is implemented with customized end devices and a gateway for evaluating the proposed architecture. In the real-time experiment, the devices and gateway are logging the pressure sensory data into the Cayenne cloud.

Evaluation of Flying Ad Hoc Network Topologies, Mobility Models, and IEEE Standards for Different Video Applications

Nowadays, drones became very popular with the enhancement of the technological progress of moving devices with a connection to each other, known as Flying Ad Hoc Network (FANET). It is used in most worldwide necessary life scenarios such as video recording, search and rescue, military missions, moving items between different areas, and many more. This leads to the necessity to evaluate different network strategies between these flying drones, which are essential to improve their quality of performance in the field. Several challenges must be addressed to effectively use FANET, to provide stable and reliable transmission for different types of data during vast changing topologies, such as different video sizes, different types of mobility models, recent Wireless Fidelity standards, types of routing protocols used, security problems, and many more. In this paper, a fully comprehensive analysis of FANET will be done to evaluate and enhance these challenges that concern different video types, mobility models, and IEEE 802.11n standards for best performance, by measuring throughput, retransmission attempt, and delay metrics. The result shows that Gauss–Markov mobility model gives the highest result using Ad Hoc On-Demand Vector and lowest delay, whereas for retransmission attempts, 2.4 GHz frequency has the lowest as it can reach more coverage area than 5 GHz.

Improving VoIP Transmission for IEEE 802.11n 5GHz MANET

In catastrophic scenarios, rescue teams need to communicate with each other without any fixed infrastructure while moving, such as search and rescue, firefighter, police, and tactical networks i.e. MANET. In these scenarios Mobile Ad hoc Networks (MANETs) can supports immediately Voice Over Internet Protocol (VoIP) service to be used, with fast deployment, low cost, and flexibility during movement. Recently the new mobile devices support the new frequency of IEEE 802.11n 5GHz that gives better performance requirements to MANET, with enhanced Quality of Service (QoS) and bandwidth (B.W). This paper will calculate and improve VoIP service in MANET that operates under IEEE 802.11n 5GHz frequency, with comparing two main routing protocols AODV and OLSR, and analyzing some QoS requirement such as end-to-end delay, throughput, and retransmission attempts using Network Simulator (NS2).

A Dual-Mode Medium Access Control Mechanism for UAV-Enabled Intelligent Transportation System

With the exponential growth in technologies for the vehicular Internet of things applications and high demands for autonomous road vehicles, future transportation systems are projected to be revolutionized on a global scale. This new landscape requires a stable, flexible, and business-friendly base of connectivity, networking, and computing technology, in which Unmanned Aerial Vehicles (UAVs) can play an important role. A UAV-enabled Intelligent Transportation System (ITS) can provide a cost-effective communication solution to improve the safety and efficiency of the transportation system, particularly if the data traffic is nonhomogeneous and nonstationary. Typically, wireless is the communication medium between vehicles and UAVs in an ITS setting, which is based on the IEEE802.11p MAC protocol adopted by car manufactures. However, the IEEE 802.11p MAC protocol is modified solely for omnidirectional antennas, which restricts network coverage, delay, and throughput. In comparison, the directional antenna has greater network coverage, spatial reuse, and bandwidth. In addition, a multiaccess edge computing (MEC) facility at the backhaul link will provide ultralow latency and high bandwidth services to meet the increasingly growing demand for latency-sensitive vehicle applications such as vehicular video data analytics, autonomous driving, and intelligent navigation. Therefore, this article aims to propose a novel dual-mode MAC protocol that can work in two antenna modes, i.e., directional and omnidirectional. For modeling and simulation purposes, we use the Optimized Network Engineering Tool (OPNET) and aim to seek an evaluation with respect to throughput, media access delay, and retransmission attempts. The results obtained demonstrate the effectiveness of the proposed scheme.

Adaptive Packet-size Control for Improved Throughput in Dynamic Access Networks

Cognitive radio (CR) is a new intelligent wireless technology that aims at improving spectrum utilization by allowing opportunistic access to the underutilized licensed spectrum. Wireless CR operating environment is typically characterized by its unreliable and unpredictable channel conditions and time availability due to fading and the randomness of primary radio (PR) activities. In such environment, packet fragmentation is needed to enhance the probability of success/packet delivery and reduce the needed number of packet re-transmission attempts. Specifically, the quality and availability of the PR channels along with the data packet size should be considered when designing communication protocols for CR networks (CRNs) such that the packet success probability is improved. Based on the quality and availability of the PR channels, an optimal-packet size metric is derived, which is defined as the packet size that can be transmitted over a selected channel while guarantying a predefined probability of success. In this paper, we propose three fragmentation-based channel assignment algorithms: fixed-fragment size algorithm, first-fit algorithm and near-exact fit algorithm. The first algorithm divides the packet equally over the selected channels while the other algorithms use variable fragment size. The main objectives of the algorithms are to enhance network throughput, decrease the number of dropped packets and reduce the average number of retransmission attempts. This preserves more channels for potential future CR transmissions, resulting in higher network throughput with less energy consumption. Simulation results show that the proposed algorithms significantly outperform existing CRN channel assignment algorithms with no fragmentation.

Quality of Services Based on Intelligent IoT WLAN MAC Protocol Dynamic Real-Time Applications in Smart Cities.

The future directions and challenges for 6G-enabled wireless communication for IoT applications are mainly focused on quality of service (QoS). The selection criteria of mobility management (MM) protocol are mainly the total duration of the delay and packet loss rate during the MM procedure. This is called intelligent handover (IH) to designate a relay with a minimum delay. To solve the problem of handover, media access control (MAC) protocols are used to provide an intelligent protocol for QoS in real-time application in mobility. Moreover, changing the parameter to find the best protocol for mobile stations in WLAN is a good choice. This paper proposed a new QoS structure for the point coordination function that is based on a new intelligent enhanced distribution coordination function that suites with dynamic real-time applications and services. The paper addresses the distributed coordination function (DCF) with QoS-based intelligent mobility management in stations and other scenarios with enhanced distribution coordination function (EDCF) to find the result of throughput, retransmission attempts, delay, and data droop. In this paper, the remote topology comprises a few remote stations and one base station within the remote LAN. All remote stations are found that each station can distinguish a transmission from any other station, and there is portability within the proposed intelligent framework.

FPV Video Adaptation for UAV Collision Avoidance

First person view (FPV) technology for unmanned aerial vehicles (UAVs) provides an immersive experience for pilots and enables various personal and commercial applications such as aerial photography, drone racing, search and rescue operations, agricultural surveillance, and structural inspection. While real time video streaming from a UAV and vision-based collision avoidance strategies have been studied in literature as separate topics, in this paper we tackle collision avoidance in FPV scenarios, taking into account network delays and real time video parameters. We present a theoretical model for obstacle collisions that considers the current communication channel conditions, the real time video parameters, and the UAV’s position relative to the closest obstacle. A video adaptation algorithm is then designed, using this metric, to tune the FPV video resolution, number of re-transmission attempts, and the modulation scheme to maximize the probability of avoiding collisions. This algorithm also takes into account specific latency constraints of the application. This video algorithm was evaluated in various scenarios and its ability to respond to both distances to the obstacle as well as the communication channel conditions was demonstrated. It was found that, for the considered scenarios, the performance of the proposed adaptive algorithm was, on an average, 58.63% higher than the closest non-adaptive one in terms of maximizing the probability of avoiding collision. Such collision avoidance strategies could be used to make UAV FPV applications safer and more reliable.

Optimizing Video Transmission Performance in 5ghz Manet

Nowadays, one of the most important technologies is video transmission. It is used worldwide across multiple platforms such as mobile, tablets, smart watches, and many more. All these devices use the 2.4GHz and 5GHz frequency ranges of IEEE 802.11. Due to the mobility of these devices, it’s very important to optimize video transmission streaming between these mobile devices with minimum delay and higher throughput. In this paper, an attempt will be made to enhance the transmission performance of video over MANET using IEEE 802.11n 5GHz frequency range supported by the new devices. Theperformance of two famous routing protocols, AODV and OLSR, is compared in terms of delay, throughput, and retransmission attempts.

Performance Analysis of Prioritization and Contention Control Algorithm in Wireless Body Area Networks

Abstract A Wireless Body Area Network (WBAN) is the composition of a group of energy-efficient, miniature, invasive/non-invasive, light-weighted sensors that monitor human body health conditions for early detection and treatment for life-threatening diseases. Due to the stringent demands of WBAN, such as energy efficiency, reliability and low delay, the development of an efficient contention control algorithm is exceptionally crucial that aims to maximize throughput by reducing collisions. In this context, this paper proposes an adaptive algorithm, namely, Prioritization and Contention Control (PCC) algorithm, to minimize collisions, latency and energy consumption. The first phase of the proposed algorithm prioritizes sensors using run-time metrics to grant channel access only for the potential nodes to send their data. It leads to a lesser number of collisions among sensors, thereby reducing retransmission attempts. In the second phase, the Contention Window (CW) size is predicted using queue length and collision rate that accurately mimic the current channel status. The dynamic estimation of CW aids in minimizing channel access delay, collisions and energy consumption, thereby enhancing overall network performance. The performance of the proposed PCC algorithm is validated with the 2D Markov model and NS2 simulation in terms of throughput, packet delivery ratio, delay and remaining energy.

Optimized link state routing protocol performance in flying ad-hoc networks for various data rates of Un manned aerial network

In the wireless communication, nowadays Flying adhoc network or UAV networks hold the most important place in the field of recent research topic. The drones or Un manned aerial vehicles which are enabled with camera, special circuit, sensors and advanced communication systems are coordinated among each other under the Network called as Flying adhoc network. FANET plays vital role in both military and civil applications. In spite of all these pros there are some unavoidable challenges and issues bonds around FANET. Since FANET possess the characteristics of dynamic rapid changing mobility, the choice of Routing protocol in FANET also open wide space in the field of Research. In our previous papers the topology based Routing protocols are analysed under different network scenarios and described the best performed one. It has been also found that the type OLSR is the better choice of FANET in terms of delay, Network load, Throughput and retransmission attempts. The OLSR routing protocol mechanism depends on the link state algorithm. It is proactive and table driven in nature. In order to maintain the topology information of the network, it completely supports the periodic exchanges of messages among themselves. OLSR is good in compacting the size of information sent in the messages. It avoids flooding by controlling the retransmissions. To exhibits this, the protocol utilizes multi point relaying techniques. It also provides optimal routes and this is completely suitable for dense and large networks. In this paper the performance of OLSR is investigated and analysed under 4 different network scenarios and different data rates. In a simulation using OPNET, the results show that the Optimized link state routing protocol has greater improved key indicators.

Towards Efficient Retransmission in Dense Networks With Interference Correlation

Exploiting the time-varying feature of wireless channels, retransmission could enable reliable data transmission. However, the growing deployment of small cell base stations (BSs) would induce significant temporal interference correlation. In consequence, once the current transmission fails, the subsequent ones are likely to fail as well. In this light, we investigate the retransmission performance in dense networks with temporally correlated interference in terms of network spatial throughput (ST). Our results reveal that the impact of temporal interference correlation on the retransmission performance critically depends on the BS density. Specifically, temporal interference correlation would cause a greater network ST attenuation when the BS density is closer to the critical density, under which network ST is maximized. Moreover, the impact of temporal interference correlation is shown to be cumulative as the number of retransmission attempts increases. Furthermore, towards efficient retransmission, we adopt and optimize a P-Activation strategy (PAS). It is shown that the optimized PAS is able to effectively mitigate the overwhelming strength and temporal correlation of interference. As a result, the retransmission performance in improving network ST is significantly enhanced in dense networks, while the variation of network ST with BS density exhibits sigmoid trend instead of the previous near-bell shape.

On energy efficient secure routing in multi-hop underlay D2D communications for IoT applications

In this paper, a physical layer security based secure routing problem in a multi-hop cognitive radio enabled device-to-device (CRD2D) communication, under the threat of multiple randomly distributed eavesdroppers (EVEs), is studied. Delivery of confidential packets between a given legitimate D2D transmitter–receiver pair is targeted with the aid of multiple intermediate legitimate D2D nodes that share spectrum of a predefined licensed∕primary user for their transmissions as unlicensed∕secondary users and operate on the principle of randomized-and-forward relaying. In view of the energy limitations of the D2D nodes engaged in IoT applications, the secure routing problem aims to maximize the secrecy energy efficiency (SEE) under the constraints of − (i) minimum secrecy rate (ii) minimum signal-to-interference plus noise ratio at any D2D receiver (iii) maximum primary user outage loss in presence of the D2D transmission (iv) maximum retransmission attempts by any D2D nodes. Based on our analysis, an optimal routing algorithm is proposed. Simulation results illustrate the dependence of SEE on various critical system parameters. Further, complexity analysis and implementation issues are also presented for the proposed routing algorithm.