Test Environmental Research Collection

Permanent URI for this collection

https://hdl.handle.net/1911/118256
This is a test collection created as part of a Fondren Fellows project (2024-2025). This collection is intended to serve as a proof of concept for a permanent collection that showcases environmental research conducted by Rice researchers. All items currently in this collection have been mapped from other collections in R-3.

Browse

Browsing Test Environmental Research Collection by Author "Aazhang, Behnaam"

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    Distributed Full-duplex via Wireless Side Channels: Bounds and Protocols
    (2013-09-16) Bai, Jingwen; Sabharwal, Ashutosh; Aazhang, Behnaam; Knightly, Edward W.
    In this thesis, we study a three-node full-duplex network, where the infrastructure node has simultaneous up- and downlink communication in the same frequency band with two half-duplex nodes. In addition to self-interference at the full-duplex infrastructure node, the three-node network has to contend with the inter-node interference between the two half-duplex nodes. The two forms of interferences differ in one important aspect that the self-interference is known at the interfered receiver. Therefore, we propose to leverage a wireless side-channel to manage the inter-node interference. We characterize the impact of inter-node interference on the network achievable rate region with and without a side-channel between the nodes. We present four distributed full-duplex inter-node interference cancellation schemes, which leverage the device-to-device wireless side-channel for improved interference cancellation. Of the four, bin-and-cancel is asymptotically optimal in high signal-to-noise ratio limit which uses Han-Kobayashi common-private message splitting and achieves within 1 bits/s/Hz of the capacity region for all values of channel parameters. The other three schemes are simpler compared to bin-and-cancel but achieve the near-optimal performance only in certain regimes of channel values. Asymptotic multiplexing gains of all proposed schemes are derived to show analytically that leveraging the side channel can be highly beneficial in increasing the multiplexing gain of the system exactly in those regimes where inter-node interference has the highest impact.
  • Thumbnail Image
    Item
    Investigating irregularly patterned deep brain stimulation signal design using biophysical models
    (Frontiers Media S.A., 2015-06) Summerson, Samantha R.; Aazhang, Behnaam; Kemere, Caleb
    Parkinson's disease (PD) is a neurodegenerative disorder which follows from cell loss of dopaminergic neurons in the substantia nigra pars compacta (SNc), a nucleus in the basal ganglia (BG). Deep brain stimulation (DBS) is an electrical therapy that modulates the pathological activity to treat the motor symptoms of PD. Although this therapy is currently used in clinical practice, the sufficient conditions for therapeutic efficacy are unknown. In this work we develop a model of critical motor circuit structures in the brain using biophysical cell models as the base components and then evaluate performance of different DBS signals in this model to perform comparative studies of their efficacy. Biological models are an important tool for gaining insights into neural function and, in this case, serve as effective tools for investigating innovative new DBS paradigms. Experiments were performed using the hemi-parkinsonian rodent model to test the same set of signals, verifying the obedience of the model to physiological trends. We show that antidromic spiking from DBS of the subthalamic nucleus (STN) has a significant impact on cortical neural activity, which is frequency dependent and additionally modulated by the regularity of the stimulus pulse train used. Irregular spacing between stimulus pulses, where the amount of variability added is bounded, is shown to increase diversification of response of basal ganglia neurons and reduce entropic noise in cortical neurons, which may be fundamentally important to restoration of information flow in the motor circuit.
  • Thumbnail Image
    Item
    MultiHop Communication is Order Optimal for Homogeneous Sensor Networks
    (2004-04-01) Chakrabarti, Arnab; Sabharwal, Ashutosh; Aazhang, Behnaam; Center for Multimedia Communications (http://cmc.rice.edu/)
    The main goal of this paper is to show that multi-hop single-user communication achieves the per node transport capacity of O(lnN/N) in homogeneous sensor networks, making it order-optimal. Our contributions in this paper are threefold. First, we construct a route-discovery and scheduling scheme based on spatial TDMA for sensor networks. Second, we show that our schedule achieves a per node transport capacity of O(lnN/N), the same as that achievable by beamforming. Third, we compare multi-hop communication and beamforming based methods in terms of the network power consumption required to attain a fixed throughput. Based on our power calculations, we conclude that if the channel attenuation is above a certain threshold (which we calculate), then multi-hop communication performs better, whereas below the threshold, beamforming is preferable.
  • Thumbnail Image
    Item
    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.