Shagufta Henna

@atu.ie

Lecturer, Department of Computing
Atlantic Technological University, Letterkenny, Co. Donegal, Ireland



                 

https://researchid.co/shaguftahenna

Shagufta Henna is Lecturer with the Department of Computing, Atlantic Technological University, Donegal, Ireland. She was a research fellow with the CONNECT, the Science Foundation Ireland Research Centre, 2019. She received her doctoral degree in Computer Science from the University of Leicester, UK, in 2013. She was an assistant professor from 2013 to 2018, Bahria University, Islamabad. She has published several scientific papers in leading journals/transactions and conferences. She has been involved in several EU and national research projects including H2020, Science Foundation of Ireland, and Enterprise of Ireland. She is a senior member of the IEEE, and is serving the editorial boards of IEEE Access, EURASIP Journal on Wireless Communications and Networking, IEEE Future Directions, and Springer Human-centric Computing and Information Sciences. She is currently supervising several PhD/Masters research students in wireless communication, deep learning, and big data analytics. She h

EDUCATION

PhD, Computer Science, University of Leicester, UK

RESEARCH INTERESTS

Deep Learning, Federated Learning, Explainable AI, Future Generation Networks, Edge Intelligence, Cybersecurity

38

Scopus Publications

Scopus Publications

  • Representation Learning for Spatial Reuse in IEEE 802.11ax-Compliance Edge Intelligence
    Stephen Azeez and Shagufta Henna

    Springer Nature Singapore

  • Ensemble consensus representation deep reinforcement learning for hybrid FSO/RF communication systems
    Shagufta Henna, Abid Ali Minhas, Muhammad Saeed Khan, and Muhammad Shahid Iqbal

    Elsevier BV

  • Rényi Differential Privacy Analysis of Graph-Based Federated Learning Under Internet of Health Things
    Mohamed Amjath and Shagufta Henna

    IEEE
    The rise of the Internet of Health Things (IoHTs) has resulted in a significant increase in collaborative initiatives among healthcare organizations employing federated learning (FL). Even though FL trains models locally to protect privacy, exchanging model parameters still creates privacy risks, especially when working with non-Euclidean data like graphs. To address this issue, differential privacy (DP) is widely used, however, choosing appropriate privacy parameters remains difficult. Therefore, this research employs Rényi Differential Privacy (RDP) analysis, which extends the capabilities of traditional DP by providing more flexibility in the selection of privacy parameters. To measure, this research first models the malware dataset as a function call graph (FCG). Subsequently, the DP-SGD-enabled DotGAT model is utilized to classify both malware and benign applications, ensuring the preservation of privacy while maintaining model utility. Finally, We empirically demonstrate that selecting Rényi divergence (a) values between 2 and 2.5 optimises the balance between privacy and utility in graph-based models within the FL setup, improving healthcare collaboration privacy.

  • Global-Local Influence Maximization Subgraph Sampling-Based Graph Representation Learning for Innate Immune Response Classification
    Mallikharjuna Rao Sakhamuri, Shagufta Henna, Leo Creedon, and Kevin Meehan

    IEEE
    An understanding of the human innate immune re-sponse has the potential to accelerate the development and clinical trials of drugs and antibiotics. This includes an understanding of T-cell responses, peptides, and the intricate interactions with Human Leukocyte Antigens (HLA). Graph based models capture the structural aspects of these interactions efficiently and graph based neural networks are the best choice of tools to analyse these datasets. However, the polymorphic nature of peptides, coupled with various influencing factors, results in the representation of HLA-peptide interactions as large complex graphs. Traditional graph-based neural networks often face challenges in processing large graphs and suffer due to their high learning and training time with reduced generalization capabilities. To address these challenges, this paper proposes an influence maximization sub-graph sampling classification approach to retain the structural information of large complex molecular graphs. This is achieved using global-local influence maximization (GLIM) that combines Page Rank with Eigenvector centrality. This unique combination enables local substructure connectivity, considering edge weights, which are critical in molecular contexts. The graph neural network (GNN) classification model achieved 0.82% accuracy on the main graphs and 0.83% accuracy on the subgraphs. More notably, the model consumed approximately 81% less memory and was about 72% faster per epoch for the subgraphs compared to the main graphs. The experimental results demonstrate the effectiveness of the subgraphs as they minimize memory resource utilization and processing time, making them a practical and efficient choice for HLA-peptide immunogenetic behavior analysis.

  • Extreme Learning Machines for Calibration and Prediction in Wireless Sensor Networks: Advancing Environmental Monitoring Efficiency
    Asif Yar, Shagufta Henna, Marion McAfee, and Salem S. Gharbia

    IEEE
    Calibrating wireless sensor network deployments, especially in uncontrolled environments, poses a significant challenge. Existing deep learning approaches for calibration perform well when resource requirements are not constrained However, conventional deep learning models are not well suited for resource constraint environments due to their computational complexity and requirement of resources. To tackle this issue, this paper introduces an extreme learning machine (ELM)-based calibration solution. ELM leverages a single-layer neural network with random weight initialization, enabling faster training and inference. Experimental results demonstrate that ELM results in accelerated learning while maintaining competitive accuracy compared to deep learning approaches like neural networks (NNs).

  • A Graph Neural Network-based Security Posture-aware Cloud Service Provider Selection for Multi-cloud
    D.S. Wijenayake, Shagufta Henna, and William Farrelly

    IEEE
    When bidirectional, data-intensive, scientific applications move through multiple cloud environments, the posture requirements change during transit. Security is crucial in this scenario as the applications and as well as infrastructure providers demand it. Previous studies were based on sub-optimal heuristics, and machine learning with no consideration for the bidirectional nature of the data workflows. This limitation is addressed in this work by adopting the graph structure and predicting cloud providers based on the specifications. GraphSAGE performed well with an AUC of 0.94 while having a trade-off between performance and cost. The research outcomes highlight the applicability of graph-based solutions to security-aware cloud service provider selection for bidirectional multi-cloud data workflows.

  • Air Pollution Monitoring Using Online Recurrent Extreme Learning Machine
    Asif Yar, Shagufta Henna, Marion McAfee, and Salem S. Gharbia

    IEEE
    Air pollution, particularly high concentrations of Ozone (O3), poses a serious threat to human health and the environment. While deep learning algorithms have proven effective in air quality forecasting, current offline models struggle to capture the dynamic, time-evolving patterns generated by continuous air pollution monitoring data. Further, the time-consuming training process and computational demands hinder the practicality of these models. This paper presents a lightweight incremental learning model tailored for O3 forecasting. To evaluate its effectiveness, real data is employed and performance is evaluated using forecasting metrics and computational time. The results reveal that the incremental learning model surpasses the state-of-the-art model widely used in O3 and time series forecasting, demonstrating both superior accuracy and computational efficiency.

  • Deep Reinforcement Learning for Advanced Persistent Threat Detection in Wireless Networks
    Kazeem Saheed and Shagufta Henna

    IEEE
    Recent cyberattacks have shifted their focus from causing financial loss or service disruption to covertly exfil-trating confidential data. Advanced Persistent Threats (APTs) pose a significant challenge due to their dynamic and sophis-ticated attack mechanisms. Unlike other cyberattacks, APTs are coordinated and targeted, executed by high-profile hackers who exploit identified vulnerabilities and deliver novel malware through phishing attacks to infiltrate networks. Traditional deep learning approaches for APT detection are static and lack adaptability, making them unsuitable for handling the dynamic and evolving attack scenarios commonly found in uncertain network traffic flows, such as multi-stage APT attacks. To address these challenges, this study proposes a Deep Reinforcement Learning approach for APT detection, referred to as APT-DRL. This approach dynamically learns from interactions with the environment, continuously adapting to emerging attack patterns. Performance evaluations demonstrate that APT-DRL effectively learns from dynamic network interactions, enabling it to formulate new policies for APT detection. Consequently, APT-DRL learns faster and achieves better accuracy compared to Feed Forward Neural Network (FNN) models, which lack the adaptability and learning capabilities of the proposed APT-DRL approach.

  • Wireless Sensor Networks Calibration using Attention-based Gated Recurrent Units for Air Pollution Monitoring
    Shagufta Henna, Asif Yar, Kazeem Saheed, and Paulson Grigarichan

    IEEE
    Calibration in wireless sensor networks (WSNs) poses a significant challenge, particularly in uncontrolled environmental deployments for environmental monitoring, such as air pollution. Traditional calibration methods rely on centralized reference stations, which are costly to maintain, offer limited coverage, and calculate measurements as averages. However, with the rise of the Internet of Things (IoT), sensors present a cost-effective alternative for calibration compared to fixed reference stations. Nevertheless, in uncontrolled environments, sensors require self-recalibration to ensure accurate measurements for the reliable operation of WSNs without human intervention. Existing calibration approaches, such as LSTM, are computationally expensive, have higher memory requirements, and exhibit training instability, making them unsuitable for resource-constrained WSNs. This paper proposes a self-calibration approach for WSNs using the Gated Recurrent Unit (GRU) coupled with the attention mechanism (Attention-GRU). The Attention-GRU selectively focuses on relevant features while capturing long-term dependencies, akin to Recurrent Neural Networks (RNNs), thereby mitigating overfitting. Experimental results demonstrate that the Attention-GRU model outperforms other models with an R-squared value of 0.97 and accelerated learning. These accurate sensor recalibration predictions promote sustainability by supporting IoT-enabled air pollution monitoring efforts.

  • Heterogeneous Graph Transformer for Advanced Persistent Threat Classification in Wireless Networks
    Kazeem Saheed and Shagufta Henna

    IEEE
    Advanced Persistent Threats (APTs) have significantly impacted organizations over an extended period with their coordinated and sophisticated cyberattacks. Unlike signature-based tools such as antivirus and firewalls that can detect and block other types of malware, APTs exploit zero-day vulnerabilities to generate new variants of undetectable malware. Additionally, APT adversaries engage in complex relationships and interactions within network entities, necessitating the learning of interactions in network traffic flows, such as hosts, users, or IP addresses, for effective detection. However, traditional deep neural networks often fail to capture the inherent graph structure and overlook crucial contextual information in network traffic flows. To address these issues, this research models APTs as heterogeneous graphs, capturing the diverse features and complex interactions in network flows. Consequently, a hetero-geneous graph transformer (HGT) model is used to accurately distinguish between benign and malicious network connections. Experiment results reveal that the HGT model achieves better performance, with 100 % accuracy and accelerated learning time, outperferming homogeneous graph neural network models.

  • Representation Learning with Attention for Spatial Reuse Optimization in Dense WLANs
    Stephen Azeez and Shagufta Henna

    Springer Nature Singapore

  • Graph Modelling and Graph-Attention Neural Network for Immune Response Prediction
    Mallikharjuna Rao Sakhamuri, Shagufta Henna, Leo Creedon, and Kevin Meehan

    IEEE
    The recent Covid-19 pandemic has attracted significant attention toward understanding the innate immune response of humans. To develop new drugs and antibiotics that activate T-cells to combat malicious pathogens, it is necessary to comprehend the immune system, including T-cell response, peptides, and Human Leukocyte Antigens (HLA) interactions. Traditional machine learning models, such as Convolutional Neural Networks (CNNs) and Feed Forward Networks (FNNs) are limited to feature extraction of peptides to predict immunogenicity values. CNNs and FNNs cannot capture the underlying structure and relationships between HLA and peptides, and therefore, do not assist with the immune response predictions. To address these issues, firstly this paper models the Immune Epitope dataset as a graph to capture dependencies and interactions among HLAs and peptides. Secondly, to assess the performance of the graph model, the results of the Graph Neural Network (GNN) are validated against the results of FNN. The results show that the GNN has better performance efficiency over conventional models in terms of accuracy and other performance metrics, thereby recommending graph-based deep learning as an efficient tool for drug discovery, diagnosis, and other immunology.

  • Multi-armed Bandit-based Channel Bonding for Off-body Communication in IEEE 802.15.6 Cognitive Radio Wireless Body Area Networks
    Shagufta Henna, Kevin Meehan, and Mallikharjuna Rao Sakhamuri

    IEEE
    Off-body communication in Cognitive Radio Wireless Body Area Networks (CRWBANs) must cope with different types of interference and dynamic traffic loads. Existing static channel assignment schemes cannot handle dynamic traffic loads with higher data rate requirements. One of the major problems experienced by CRWBANs is contention across wireless body area networks, thereby affecting the network throughput. Channel bonding has been successfully applied to different networks, such as Wireless Local Area Networks (WLANs), cognitive radio sensor networks, and wireless sensor networks. However, its use for the off-body communication in IEEE 802.15.6-based CRWBANs has not been investigated. This article proposes a multi-armed bandit-based bonded channel algorithm (MAB-BCA) with Upper Confidence Bound (UCB) for channel bonding to improve the off-body network capacity. The MAB-BCA based on UCB algorithm maximizes the capacity of off-body communication in CRWBANs. It demonstrates significant performance improvement over Static Channel Assignment (SCA) and Reinforcement Learning—Channel Assignment Algorithm (RL-CAA) in terms of average throughput and comparable bit error rate and dissatisfaction probability.

  • Multi-Graph Convolutional Neural Network for Breast Cancer Multi-task Classification
    Mohamed Ibrahim, Shagufta Henna, and Gary Cullen

    Springer Nature Switzerland
    AbstractMammography is a popular diagnostic imaging procedure for detecting breast cancer at an early stage. Various deep-learning approaches to breast cancer detection incur high costs and are erroneous. Therefore, they are not reliable to be used by medical practitioners. Specifically, these approaches do not exploit complex texture patterns and interactions. These approaches warrant the need for labelled data to enable learning, limiting the scalability of these methods with insufficient labelled datasets. Further, these models lack generalisation capability to new-synthesised patterns/textures. To address these problems, in the first instance, we design a graph model to transform the mammogram images into a highly correlated multigraph that encodes rich structural relations and high-level texture features. Next, we integrate a pre-training self-supervised learning multigraph encoder (SSL-MG) to improve feature presentations, especially under limited labelled data constraints. Then, we design a semi-supervised mammogram multigraph convolution neural network downstream model (MMGCN) to perform multi-classifications of mammogram segments encoded in the multigraph nodes. Our proposed frameworks, SSL-MGCN and MMGCN, reduce the need for annotated data to 40% and 60%, respectively, in contrast to the conventional methods that require more than 80% of data to be labelled. Finally, we evaluate the classification performance of MMGCN independently and with integration with SSL-MG in a model called SSL-MMGCN over multi-training settings. Our evaluation results on DSSM, one of the recent public datasets, demonstrate the efficient learning performance of SSL-MNGCN and MMGCN with 0.97 and 0.98 AUC classification accuracy in contrast to the multitask deep graph (GCN) method Hao Du et al. (2021) with 0.81 AUC accuracy.

  • Erratum: Performance Evaluation of LoRaWAN for Green Internet of Things (IEEE Access (2019) 7 (164102-164112) DOI: 10.1109/ACCESS.2019.2943720)
    Zulfiqar Ali, Shagufta Henna, Adnan Akhunzada, Mohsin Raza, and Sung Won Kim

    Institute of Electrical and Electronics Engineers (IEEE)

  • Distributed and Collaborative High-Speed Inference Deep Learning for Mobile Edge with Topological Dependencies
    Shagufta Henna and Alan Davy

    Institute of Electrical and Electronics Engineers (IEEE)
    Ubiquitous computing has potentials to harness the flexibility of distributed computing systems including cloud, edge, and Internet of Things devices. Mobile edge computing (MEC) benefits time-critical applications by providing low latency connections. However, most of the resource-constrained edge devices are not computationally feasible to host deep learning (DL) solutions. Further, these edge devices if deployed under denser deployments result in topological dependencies which if not taken into consideration adversely affect the MEC performance. To bring more intelligence to the edge under topological dependencies, compared to optimization heuristics, this article proposes a novel collaborative distributed DL approach. The proposed approach exploits topological dependencies of the edge using a resource-optimized graph neural network (GNN) version with an accelerated inference. By exploiting edge collaborative learning using stochastic gradient (SGD), the proposed approach called CGNN-edge ensures fast convergence and high accuracy. Collaborative learning of the deployed CGNN-edge incurs extra communication overhead and latency. To cope, this article proposes compressed collaborative learning based on momentum correction called cCGNN-edge with better scalability while preserving accuracy. Performance evaluation under IEEE 802.11ax-high-density wireless local area networks deployment demonstrates that both the schemes outperform cloud-based GNN inference in response time, satisfaction of latency requirements, and communication overhead.

  • Attenuation-based hybrid RF/FSO link using soft switching
    Abid Ali Minhas, Muhammad Saeed Khan, Shagufta Henna, and Muhammad Shahid Iqbal

    SPIE-Intl Soc Optical Eng
    Abstract. Due to high data rates, license-free spectrum, and immunity to electromagnetic interference, free-space optical (FSO) links are being considered as a potential candidate to meet the ever-increasing traffic demands of users. The FSO links remain less explored, as their performance depends on environmental conditions such as dust, fog, and clouds. Such conditions do not affect the radio frequency (RF) links in a similar way; however, RF resources are scarce. As an ultimate solution to this performance/scarcity dilemma, we propose a fuzzy logic-based hybrid architecture of FSO and RF links, which can be used to enhance reliability and resource efficiency. We present an intelligent soft switching mechanism between FSO and RF links using a fuzzy inference system to achieve the maximum link reliability and provide heterogeneous wireless services.

  • Modeling Human Innate Immune Response Using Graph Neural Networks
    Shagufta Henna

    Institute of Electrical and Electronics Engineers (IEEE)
    Since the rapid outbreak of Covid-19, profound research interest has emerged to understand the innate immune response to viruses to enable appropriate vaccination. This understanding can help to inhibit virus replication, prolong adaptive immune response, accelerated virus clearance, and tissue recovery, a key milestone to combat coronaviruses (CoVs), e.g., Covid-19. An innate immune system triggers inflammatory responses against CoVs upon recognition of viruses. An appropriate defense against various coronavirus strains requires a deep understanding of the innate immune response system. Current deep learning approaches focus more on Covid-19 detection and pay no attention to understand the immune response once a virus invades. In this work, we propose a graph neural network-based (GNN) model that exploits the interactions between pattern recognition receptors (PRRs)to understand the human immune response system. PRRs are germline-encoded proteins that identify molecules related to pathogens and initiate a defense mechanism against the related pathogens, thereby aiding the innate immune response system. An understanding of PRR interactions can help to recognize pathogen-associated molecular patterns (PAMPs) to predict the activation requirements of each PRR. The immune response information of each PRR is derived from combining its historical PAMPs activation coupled with the modeled effect on the same from PRRs in its neighborhood. On one hand, this work can help to understand how long Covid-19 can confer immunity for a strong immune response. On the other hand, this GNN-based understanding can also abode well for appropriate vaccine development efforts against CoVs. Our proposal has been evaluated using CoVs immune response dataset, with results showing an average IFNs activation prediction accuracy of 90%, compared to 85% using feed-forward neural networks.

  • Collaborative Wireless Power Transfer in Wireless Rechargeable Sensor Networks
    Azka Amin, Xi-Hua Liu, Muhammad Asim Saleem, Shagufta Henna, Taseer-ul Islam, Imran Khan, Peerapong Uthansakul, Muhammad Zeshan Qurashi, Seyed Sajad Mirjavadi, and Masoud Forsat

    Hindawi Limited
    Wireless power transfer techniques to transfer energy have been widely adopted by wireless rechargeable sensor networks (WRSNs). These techniques are aimed at increasing network lifetime by transferring power to end devices. Under these wireless techniques, the incurred charging latency to replenish the sensor nodes is considered as one of the major issues in wireless sensor networks (WSNs). Existing recharging schemes rely on rigid recharging schedules to recharge a WSN deployment using a single global charger. Although these schemes charge devices, they are not on-demand and incur higher charging latency affecting the lifetime of a WSN. This paper proposes a collaborative recharging technique to offload recharging workload to local chargers. Experiment results reveal that the proposed scheme maximizes average network lifetime and has better average charging throughput and charging latency compared to a global charger-based recharging.

  • Deep Reinforcement Learning for Topology-Aware VNF Resource Prediction in NFV Environments
    Nikita Jalodia, Shagufta Henna, and Alan Davy

    IEEE
    Network Function Virtualisation (NFV) has emerged as a key paradigm in network softwarisation, enabling virtualisation in future generation networks. Once deployed, the Virtual Network Functions (VNFs) in an NFV application’s Service Function Chain (SFC) experience dynamic fluctuations in network traffic and requests, which necessitates dynamic scaling of resource instances. Dynamic resource management is a critical challenge in virtualised environments, specifically while balancing the trade-off between efficiency and reliability. Since provisioning of virtual infrastructures is time-consuming, this negates the Quality of Service (QoS) requirements and reliability criterion in latency-critical applications such as autonomous driving. This calls for predictive scaling decisions to balance the provisioning time sink, with a methodology that preserves the topological dependencies between the nodes in an SFC for effective resource forecasting. To address this, we propose the model for an Asynchronous Deep Reinforcement Learning (DRL) enhanced Graph Neural Networks (GNN) for topology-aware VNF resource prediction in dynamic NFV environments.

  • An internet of things (IoT)-Based coverage monitoring for mission critical regions
    Shagufta Henna, Alan Davy, Hasan Ali Khattak, and Abid Ali Minhas

    IEEE
    Barrier coverage is one of the popular applications of Wireless Sensor Networks (WSNs). A barrier construction algorithm which takes into account both energy efficiency and fault tolerance is critical for the security of mission-critical regions. Sensor devices of a sensor network have the capability to monitor and understand the critical environment, and if part of the internet of things (IoT), they can communicate this information to a remote location for immediate action. This paper deals with the barrier coverage achieved through sensor nodes and communicate coverage information to a mission partner agency. The contributions of this paper are two folds. First, we propose a disjoint barrier construction algorithm based on the residual energy of sensors. Second, we propose an IoT-enabled paradigm to report barrier coverage information to a mission partner agency for immediate action. Simulation results show that the proposed algorithm improves barrier coverage and ensures better barrier lifetime compared to 2- barrier and LABC algorithms.

  • Performance Evaluation of LoRaWAN for Green Internet of Things
    Zulfiqar Ali, Shagufta Henna, Adnan Akhunzada, Mohsin Raza, and Sung Won Kim

    Institute of Electrical and Electronics Engineers (IEEE)
    LoRa is a long-range, low power and single-hop wireless technology that has been envisioned for Internet of Things (IoT) applications having battery driven nodes. Nevertheless, increase in number of end devices and varying throughput requirements impair the performance of pure Aloha in LoRaWAN. Considering these limitations, we evaluate the performance of slotted Aloha in LoRaWAN using extensive simulations. We employed packet error rate (PER), throughput, delay, and energy consumption of devices under different payload sizes and varying number of end devices as benchmarks. Moreover, an analytical analysis of backlogged and non-backlogged under slotted Aloha LoRaWAN environment is also performed. The simulation shows promising results in terms of PER and throughput compared to the pure Aloha. However, increase in delay has been observed during experimental evaluation.Finally, we endorse slotted aloha LoRaWAN for Green IoT Environment.

  • An efficient precoding algorithm for mmWave massive MIMO systems
    Imran Khan, Shagufta Henna, Nasreen Anjum, Aduwati Sali, Jonathan Rodrigues, Yousaf Khan, Muhammad Irfan Khattak, and Farhan Altaf

    MDPI AG
    Symmetrical precoding and algorithms play a vital role in the field of wireless communications and cellular networks. This paper proposed a low-complexity hybrid precoding algorithm for mmWave massive multiple-input multiple-output (MIMO) systems. The traditional orthogonal matching pursuit (OMP) has a large complexity, as it requires matrix inversion and known candidate matrices. Therefore, we propose a bird swarm algorithm (BSA) based matrix-inversion bypass (MIB) OMP (BSAMIBOMP) algorithm which has the feature to quickly search the BSA global optimum value. It only directly finds the array response vector multiplied by the residual inner product, so it does not require the candidate’s matrices. Moreover, it deploys the Banachiewicz–Schur generalized inverse of the partitioned matrix to decompose the high-dimensional matrix into low-dimensional in order to avoid the need for a matrix inversion operation. The simulation results show that the proposed algorithm effectively improves the bit error rate (BER), spectral efficiency (SE), complexity, and energy efficiency of the mmWave massive MIMO system as compared with the existing OMP hybrid and SDRAltMin algorithm without any matrix inversion and known candidate matrix information requirement.

  • An Adaptive Backoff Mechanism for IEEE 802.15.4 Beacon-Enabled Wireless Body Area Networks
    Shagufta Henna and Muhammad Awais Sarwar

    Hindawi Limited
    Carrier sense multiple access mechanism with collision avoidance (CSMA/CA) in IEEE 802.15.4-based wireless body area networks (WBANs) may impair the transmission reliability of emergency traffic under high traffic loads, which may result in loss of high valued medical information. Majority of the recent proposals recommend an early retransmission of failed frame while ignoring the history of past failed transmissions. More importantly, these proposals do not consider the number of failed transmissions experienced by each sensor node, thereby affecting the reliability of retransmissions. In this paper, we propose a dynamic retransmission adaptive intelligent MAC (RAI-MAC) scheme. In our proposed scheme retransmission class of each sensor node is decided by the coordinator according to the number of failed transmissions of each node as observed by the coordinator during the last superframe. Based on the retransmission class received from the coordinator, each node adjusts its next backoff value. The proposed scheme increases the probability of successful frame retransmissions without incurring extra overhead. The simulation results prove that the proposed scheme based on its adaptive retransmission mechanism achieves higher average throughput and average end-to-end delay, while not compromising on energy efficiency as compared to the IEEE 802.15.4 and Block Acknowledgment (Block Ack). Moreover, our scheme appears more stable in terms of average throughput, end-to-end delay, and energy efficiency under different values of beacon order (BO) and superframe order (SO).

  • Evaluation of propagation path delay using 3D scattered model in LoRaWAN