Electrical and Electronic Engineering - Research Publications

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Author: Nirmalathas, Ampalavanapillai × Start date: 2010 × End date: 2020 ×

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Now showing 1 - 10 of 41
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    Dynamic scheduling algorithm for LTE uplink with smart-metering traffic
    Amarasekara, B ; Ranaweera, C ; Evans, R ; Nirmalathas, A (WILEY, 2017-10)
    Abstract Long‐term evolution (LTE) is a promising last mile access candidate technology for the smart‐metering communication architecture. However, when the mobile LTE network is used to support smart meters (SMs), the quality‐of‐service (QoS) requirements of the smart‐metering traffic as well as all the other typical mobile network traffic need to be ensured. This becomes problematic when the network users generate diverse traffic types that have different QoS requirements. Therefore, in this paper, we propose a dynamic bandwidth scheduling algorithm to ensure the required QoS of various traffic types arising from both SMs and mobile users. Our proposed dynamic bandwidth allocation algorithm integrates two schedulers that are designed for periodic and emergency SM traffic situations that have different SM traffic intensities and QoS requirements. Designing of two schedulers provides the advantages of leveraging the particular traffic characteristics of these two diverse operational situations and achieving the maximum use of resources to ensure QoS requirements. In addition, to alleviate potential problems created by simultaneous emergency SM traffic, we also propose a method that deploys a random delay for SM packet transmissions. We analyse the delay and packet drop ratio of diverse traffic types when both the LTE base station scheduler and the SMs deploy our proposed methods under either periodic or emergency SM traffic conditions in the smart grid. Our results show that our proposed mechanisms are capable of satisfying the QoS requirements of both mobile users and SMs under diverse traffic conditions.
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    Secure multiple access for indoor optical wireless communications with time-slot coding and chaotic phase
    Liang, T ; Wang, K ; Lim, C ; Wong, E ; Song, T ; Nirmalathas, A (OPTICAL SOC AMER, 2017-09-04)
    In this paper, we report a novel mechanism to simultaneously provide secure connections for multiple users in indoor optical wireless communication systems by employing the time-slot coding scheme together with chaotic phase sequence. The chaotic phase sequence is generated according to the logistic map and applied to each symbol to secure the transmission. Proof-of-concept experiments are carried out for multiple system capacities based on both 4-QAM and 16-QAM modulation formats, i.e. 1.25 Gb/s, 2 Gb/s and 2.5 Gb/s for 4-QAM, and 2.5 Gb/s, 3.33 Gb/s and 4 Gb/s for 16-QAM. Experimental results show that in all cases the added chaotic phase does not degrade the legitimate user's signal quality while the illegal user cannot detect the signal without the key.
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    Indoor infrared optical wireless localization system with background light power estimation capability
    Wang, K ; Nirmalathas, A ; Lim, C ; Alameh, K ; Li, H ; Skafidas, E (Optica Publishing Group, 2017-09-18)
    The indoor user localization function is in high demand for high-speed wireless communications, navigations and smart-home applications. The optical wireless technology has been used to localize end users in indoor environments. However, its accuracy is typically very limited, due to the ambient light, which is relatively strong. In this paper, a novel high-localization-accuracy optical wireless based indoor localization system, based on the use of the mechanism that estimates background light intensity, is proposed. Both theoretical studies and demonstration experiments are carried out. Experimental results show that the accuracy of the proposed optical wireless indoor localization system is independent on the localization light strength, and that an average localization error as small as 2.5 cm is attained, which is 80% better than the accuracy of previously reported optical wireless indoor localization systems.
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    An Efficient Resource Allocation Mechanism for LTE-GEPON Converged Networks
    Ranaweera, C ; Wong, E ; Lim, C ; Nirmalathas, A ; Jayasundara, C (SPRINGER, 2014-07)
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    Compound nanostructure of metallic nanoholes with 1D photonic crystal for multispectral imaging applications
    He, X ; Liu, Y ; Uddin, H ; Nirmalathas, A ; Unnithan, RR (OSA Publishing, 2020)
    This paper demonstrates a single sensor based multispectral spectral imaging camera using a hybrid RGB colour mosaic made of plasmonic and 1D photonic crystal layers.
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    Approaches to improve performance of 60 GHz radio-0verFiber fronthaul links
    Lim, C ; Tian, Y ; Nirmalathas, A ; Lee, KL (OSA Publishing, 2020)
    In this paper, we review the work we have done to improve the performance of users located at the cell boundary of a 60 GHz radio-over-fibre fronthaul using coordinated-multipoint (CoMP) together with non-orthogonal-multiple-access (NOMA).
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    An IoT-owned service for global IoT device discovery, integration and (Re)use
    Dawod, A ; Georgakopoulos, D ; Jayaraman, PP ; Nirmalathas, A (IEEE, 2020)
    This paper introduces a novel IoT-owned service for Global IoT Device Discovery and Integration (GIDDI) of existing IoT devices that are owned and managed by different parties who are the IoT devices providers. The GIDDI service promotes the sharing of existing IoT devices and the deployment of new devices via a revenue generating scheme for the IoT device providers. Unlike existing IoT device discovery and integration solutions that are currently owned and/or controlled by specific IoT platform or service providers, the GIDDI service has been specifically designed to manage all the metadata needed for IoT device discovery and integration in a specialized blockchain (we refer to this as GIDDI Blockchain) and via this blockchain-based solution be IoT-owned (i.e., not owned or controlled by any specific provider). In addition to the GIDDI Blockchain, the GIDDI service includes a distributed GIDDI Marketplace that provides the functionality of IoT device discovery, integration and payment. The paper describes a proof-of-concept implementation of the GIDDI blockchain. It also provides an experimental evaluation of the GIDDI blockchain in variety of IoT device registration and query workloads. An evaluation of the proposed GIDDI service concludes the paper.
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    Multi-Level Code NOMA for Radio-over-Fiber based Fronthaul Links
    Lim, C ; Tao, Y ; Nirmalathas, A (IEEE, 2020)
    The inherent centralized control architecture of radio-over-fiber (RoF) enables advanced coordination functionality to be implemented in a RoF-based mobile fronthaul to facility network management and coordination. This advanced coordination functionality enhances the performance of disadvantaged end users located further away from the remote radio head (RRH) or at the cell edges. In this paper, we review our work incorporating multi-level code based non-orthogonal multiple access (NOMA) to improve the performance of users located further away from the RRH with poor channel gain.
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    Performance Analysis of Software-Defined Multihop Wireless Sensor Networks
    Jurado-Lasso, FF ; Clarke, K ; Nirmalathas, A (Institute of Electrical and Electronics Engineers (IEEE), 2020)
    In this article, we propose a model-based characterization of energy consumption in a software-defined wireless sensor network (SD-WSN) architecture in an effort to examine the implications for network performance when making the WSN reprogrammable. The proposed model consists of breaking down all key functions involved in the correct functioning of an SD-WSN, namely; neighbor discovery, neighbor advertisement, network configuration, and data collection. The model is analyzed from a multihop network perspective. We consider two static SD-WSN scenarios to examine scalability, and one scenario to assess the performance implications in a pseudo-dynamic SD-WSN. Extensive simulation results are presented regarding the control overhead introduced, the percentage of alive nodes and remaining energy, and the impacts on network lifetime. We show that the accumulated control overhead is inversely proportional to the interaction period with the controller, whereas the remaining energy and the network lifetime are directly proportional to this parameter. Results show that the control overhead, for static SD-WSNs, can take up to 10%–29% of the total data flowing to the controller for the large SD-WSN and 6–19% for the small SD-WSN. For a pseudo-dynamic network, the control overhead can take up to two-thirds of the total data sent to the controller, and the network lifetime was reduced by up to 80% compared with the static scenarios.
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    A Software-Defined Management System for IP-Enabled WSNs
    Jurado-Lasso, FF ; Clarke, K ; Nirmalathas, A (Institute of Electrical and Electronics Engineers (IEEE), 2020-06)
    Software-defined networking (SDN) offers potential pathways to overcome the management complexity of the Internet of Things (IoT). Previous studies have often been limited to software simulations or general proposals only. In this article, we design and evaluate an SDN-based management system for wireless sensor networks (WSNs) using IPv6 over low-power wireless personal area networks (6LoWPAN). The framework is described in detail covering different data-, control-, and application-plane implementations, and includes a novel addressing scheme and packet format. It also uses a centralized routing protocol, located at the SDN controller, based on the shortest path algorithm. We compare our approach with the routing protocol for low-power and lossy networks (RPL), which uses a distributed routing protocol. Hardware tests were carried out in a dynamic environment, with multiple sources of interference for different payload sizes to evaluate the impacts and practicality of SDN in WSNs. The performance comparison shows that the proposed SDN management system for IP-enabled WSNs using a centralized routing protocol outperforms the RPL protocol in terms of round-trip time, jitter, memory consumption, and packet loss rate (PLR), despite the control overhead introduced.