Electrical and Electronic Engineering - Research Publications
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ItemNo Preview AvailableSecure multiple access for indoor optical wireless communications with time-slot coding and chaotic phase(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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ItemNo Preview AvailableIndoor infrared optical wireless localization system with background light power estimation capability(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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ItemAn Efficient Resource Allocation Mechanism for LTE-GEPON Converged Networks(SPRINGER, 2014-07)
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ItemNo Preview AvailableApproaches to improve performance of 60 GHz radio-0verFiber fronthaul links(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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ItemNo Preview AvailableMulti-Level Code NOMA for Radio-over-Fiber based Fronthaul Links(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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ItemIndoor Optical Wireless Communications using Few-mode Based Uniform Beam Shaping and LMS Based Adaptive Equalization(IEEE, 2020-09-01)An indoor optical wireless communication system employing few-mode based uniform beam shaping and adaptive LMS equalization is demonstrated. Results show that superior uniformity is obtained and LMS equalization with step size of 0.01 and tap length of 45 achieves the best performance.
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ItemDemonstration of High-speed Indoor Optical Wireless Communications using Few-mode Based Uniform Beam Shaping(IEEE, 2020-10-04)A high-speed indoor optical wireless communications link using few-mode based uniform beam shaping is experimentally demonstrated. Results show that high-quality uniform beam can be realized and the BER performance can be improved significantly by combining the signals from different channels supported by different modes.
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ItemGigabit/s Optical Wireless Access and Indoor Networks(OSA - Optical Society of America, 2020)Optical wireless networks are being explored as a wireless alternative for provision of multi gigabits/second wireless and this paper presents an overview of recent progress and outstanding challenges. and technologies.
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ItemMAC protocol for indoor optical wireless networks(Institution of Engineering and Technology, 2019-11-03)Optical wireless communication has emerged as a promising candidate for future high data rate indoor applications such as virtual reality. Even though physical layer of optical wireless networks has rapidly developed during last decade, upper layer architecture that harness the physical layer capabilities has not yet been developed in the same pace. To this end, the authors develop a novel contention-based medium access control (MAC) protocol that accompanies a service differentiation mechanism and a dynamic contention window tuning algorithm. The proposed service differentiation mechanism can identify the diverse traffic types and facilitate their throughput and delay requirements. To add more robustness to the contention-based MAC protocol which depends on contention windows to avoid collisions, the authors also propose an algorithm that dynamically changes the contention window sizes to suit the congestion level. They analyse the performance of the proposed MAC protocol under diverse network configurations and they show that it is far more effective to use end-user network metrics such as throughput in dynamic adaptation algorithms in addition to collision rate due to the wide range of traffic types present in the network. The proposed results demonstrate that the proposed MAC protocol can handle next-generation traffic types and their stringent latency requirements in an effective manner.