Browsing by Author "Naribole, Sharan"

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    Enhanced WLAN Performance with New Spectrum at 60 GHz and Visible Light
    (2018-03-01) Naribole, Sharan; Knightly, Edward W.
    To enhance the WLAN operation at sub-6 GHz, research has been directed towards utilizing new spectral bands including millimeter waves (60 GHz) and visible light spectrum. The 7-14 GHz unlicensed band at 60 GHz can enable multi-gigabit rate applications including live HD video streaming, virtual reality, etc. Visible light communication (VLC) is a key emerging energy-efficient communication technology that dual purposes LED-based lighting infrastructure for both illumination and communication. Although both these bands have the potential to enhance WLAN performance, each of them possesses unique physical properties that hinder some existing services readily available in sub-6 GHz bands. First, the strong directionality required at 60 GHz precludes serving all clients in a multicast group with a single transmission and instead is comprised of a sequence of beam-formed transmissions that together cover all multicast group members. I design, implement, and experimentally evaluate scalable directional multicast (SDM) as a technique to address the challenges imposed by directional communication for a scalable multicast service at 60 GHz. Second, the wide coverage and relatively high transmit power realized by the VLC downlink to satisfy the illumination objective is problematic to realize on the uplink. I design, analyze, and implement LiRa, a Light-Radio WLAN that fuses light and radio capabilities in an integrated system design without requiring mobile devices to emit light or infrared. I design an uplink control channel for LiRa that is Wi-Fi compliant, has a controllable impact on airtime taken from legacy Wi-Fi clients, and efficiently scales with increasing VLC user population. Third, contention-based uplink radio access might lead to significant degradation in airtime efficiency and energy efficiency as the time spent “awake” by the radio is dependent on the network traffic conditions. I design and evaluate LiSCAN, a VLC uni-directional control channel that enables virtual full-duplex contention-free operation of uplink radio access. My analysis shows that LiSCAN can provide significant improvements in the radio airtime efficiency, the sessions delivered with pre-defined service quality requirements and energy savings.
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    Small Cells and Mobile Clients: a Measurement Study of an Operational Network
    (2014-06-26) Naribole, Sharan; Knightly, Edward W.; Aazhang, Behnaam; Zhong, Lin
    Small cells address the increasing traffic demands from mobile users and target improved coverage and capacity and better quality of experience to users. This thesis presents the first large-scale measurement study of voice and data service performance of an operational small cell cellular network. Nation-wide fine-grained voice service measurements are analyzed to gain insight into the nature and implications of handovers on voice service performance. A new statistical correlation framework to find the statistical dependency between two events across multiple cells is proposed. The effectiveness of the proposed framework is demonstrated using data service quality measurements of a relatively higher traffic demand location. This in-depth study targets a better understanding of the advantages and trade-offs of deploying small cells in operational networks and provides a foundation for future studies of mobility management and development of techniques for improvement of service performance.