Electrical and Electronic Engineering - Research Publications

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Start date: 2010 × End date: 2019 × Author: Skafidas, Efstratios × Author: Nirmalathas, Ampalavanapillai × Author: Lim, Christina ×

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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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    Experimental demonstration of free-space based 120 Gb/s reconfigurable card-to-card optical interconnects
    Wang, K ; Nirmalathas, A ; Lim, C ; Skafidas, E ; Alameh, K (OPTICAL SOC AMER, 2014-10-01)
    In this Letter, we propose and experimentally demonstrate a free-space based reconfigurable card-to-card optical interconnect architecture with 16-carrierless-amplitude-phase modulation. Experimental results show that up to 120 Gb/s (3×40  Gb/s) flexible interconnection can be achieved for up to 30 cm distance with a worst-case receiver sensitivity of -9.70  dBm.
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    High-speed indoor optical wireless communication system with single channel imaging receiver
    Wang, K ; Nirmalathas, A ; Lim, C ; Skafidas, E (OPTICAL SOC AMER, 2012-04-09)
    In this paper we experimentally investigate a gigabit indoor optical wireless communication system with single channel imaging receiver. It is shown that the use of single channel imaging receiver rejects most of the background light. This single channel imaging receiver is composed of an imaging lens and a small photo-sensitive area photodiode attached on a 2-axis actuator. The actuator and photodiode are placed on the focal plane of the lens to search for the focused light spot. The actuator is voice-coil based and it is low cost and commercially available. With this single channel imaging receiver, bit rate as high as 12.5 Gbps has been successfully demonstrated and the maximum error-free (BER<10⁻⁹) beam footprint is even larger than 1 m. Compared with our previous experimental results with a single wide field-of-view non-imaging receiver, an improvement in error-free beam footprint of >20% has been achieved. When this system is integrated with our recently proposed optical wireless based indoor localization system, both high speed wireless communication and mobility can be provided to users over the entire room. Furthermore, theoretical analysis has been carried out and the simulation results agree well with the experiments. In addition, since the rough location information of the user is available in our proposed system, instead of searching for the focused light spot over a large area on the focal plane of the lens, only a small possible area needs to be scanned. By further pre-setting a proper comparison threshold when searching for the focused light spot, the time needed for searching can be further reduced.