Research Projects

Synchronized Opportunistic Routing for Duty-Cycled Networks

Opportunistic routing is an emerging routing technique that leverages the spatial diversity of wireless links to improve the efficiency of bulk data transmission. This project proposed and implemented a cross-layer data forwarding protocol in TinyOS (an embedded OS), which applies opportunistic routing techniques in low-power wireless networks for a significant increase in data transmission efficiency with low duty cycle. A paper is submitted to IPSN '14 and is currently under review.

Data-driven Wireless Link Quality Estimation and Prediction

In this project, I designed and implemented a novel wireless link quality estimation scheme based on data-driven prediction models, and evaluated their network performance in multiple wireless sensor network testbeds with more than 180 sensor nodes. Specifically, I utilized logistic regression based models as well as efficient online learning algorithms to predict short temporal quality variations of wireless links. The models were implemented with efficiency in mind such that they can run sufficiently fast in the resource constrained sensor nodes. The implementation also includes modifications to almost all parts of existing networking stacks in TinyOS, from MAC layer to the network layer. For this project, three papers are published in SECON '09, IPSN '11 and SenSys '12 respectively.

Solar Radiation Mapping and Prediction

The goal of this project is to build and test an Affordable System for Solar Irradiance Sens- ing and Tracking (ASSIST) that can observe localized solar irradiance conditions with previ- ously unattainable spatiotemporal resolution using COTS sensors. ASSIST adopts a tiered- architecture where a small number of expensive and highly calibrated solar observatories get complemented by a larger number of inexpensive but uncalibrated sensor nodes. I co-designed the sensing platform of a solar dome instrument which consists of an Arduino broad coupled with 13 multiplexers and 206 solar irradiance sensors. I also participated in several deployment operations to install ASSIST nodes to multiple sites, including a 1 MW solar power plant.

Occupancy-based Building Energy Management System Actuation

This project builds a system using a wireless camera sensor node based on Memsic Imote2 combined with an IMB400 camera board to actuate a building energy management system by computing the number of occupants in a monitored area. I participated in building the demo for BuildSys '11 (co-authored) where the audience could experience the interaction between an area's occupancy and the different control surfaces (lighting, ventilation).

Witness Assisted Lost Object Tracking System

Co-designed SenSearch, an outdoors, GPS assisted personnel tracking system using MicaZ motes and MTS420CC GPS module. My responsibilities include developing TinyOS program for GPS data gathering and reliable data exchange in a delay tolerant network. The related paper is published in ADHOCNOW '09 (co-author).

UC Merced Wireless Sensor Network Testbed

Co-designed and installed a 75-node TelosB-based wireless sensor network testbed. All nodes are attached to firmware-modified Linksys NSLU2 network storage devices via USB hubs. The Linksys NSLU2 device is used to bridge serial communication between the nodes and a central server over the local network using a modified version of USB/IP, an open source project that creates a general USB device sharing system over IP network. The Linksys NSLU2 were upgraded to SheevaPlug later at 2009.