Wireless Single Channel Full-Duplex Radios

This project explores the design of a single channel full-duplex wireless transceiver. The design uses a combination of RF and baseband techniques to achieve full-duplexing with minimal effect on link reliability. Experiments on real nodes show the full-duplex scheme achieves a median gain of 84% in aggregate throughput as compared to traditional half-duplexing wireless for a single hop network.

This project introduces Antenna Cancellation, a novel technique for self-interference cancellation. In conjunction with existing RF interference cancellation and digital base- band intereference cancellation, antenna cancellation achieves the amount of self-interference cancellation required for full- duplex operation.

Their are significant potential MAC and network gains with full-duplexing A full-duplex system can solve some important problems with existing wire- less systems including hidden terminals, loss of throughput due to congestion, and large end-to-end delays.

Meru Virtual World Architecture

The Meru Project is designing and implementing an architecture for the virtual worlds of the future. Virtual worlds today exhibit properties that prevent success similar to applications such as the Web: they scale poorly, have centralized control, or cannot be easily extended. Our work focuses on solving the scalability challenges of virtual worlds by making geometric and physically based constraints an integral part of our architecture. Moreover, we address the issues of federation and extensibility by carefully separating the components of a virtual world, allowing each component to develop independently.

MNet Architecture

The MNet architecture explores how to architecturally improve sensor networking. The core principle of the architecture is to minimize the energy cost of diagnosing network behavior, transforming the typical "black box" embedded sensornet to a well-understood and transparent system that is easy to optimize, manage, and deploy.

Building-Scale Power Analysis (PowerNet)

Current power conservation research and development is hampered by a lack of comprehensive power usage data. We are designing and deploying a building-scale sensor network for power measurement and analysis. The network will consist of custom high fidelity wireless sensors, virtual power monitors based on power modeling techniques. This network will monitor the power consumption of a full spectrum of electronics, including end-user systems, back-end systems, and the networking infrastructure. Additionally, it will monitor the utilization of the measured systems to enable correlation between system use and power consumption. Our broader goal is to generate the comprehensive insights that can guide power research across system types and scales (individual system, data center, networking infrastructure, hardware and software).

Past Projects

Infectious Disease Spread

In January 2010, we set out to collect data on all close proximity interactions in a closed network - a U.S. high school. We recruited over 700 people - students, teachers, and staff - and asked them to wear wireless TelosB motes around their necks for a day. Every 20 seconds, the motes broadcast 'Hello' messages, with nearby nodes recording what they heard. At the end of the school day, we collected enough data to reconstruct the real-life social network of the entire school. We later used this data to study the spread of infectious diseases such as the flu. The website includes the dataset used in our work.

Measuring Low-Power Wireless

We measure the temporal and spatial behavior of modern low-power wireless radios. Current work focuses on 802.15.4, due to its increasing importance in sensornets, home automation, and the 6lowpan community. Measuring many platforms and environments can separate hardware-specific and enviromental effects from more general ones. The results enable better theoretical formulations, improve protocols, and lead to better and more accurate simulation, and measurement tools.

Data sets: Packet traces from Mirage (micaz), Omega (Telos), SWAN (802.11) and Shuttle (802.11) networks

Software: The Stanford Wireless Analysis Tool

Operating System/Language Co-Design

TinyOS is the de-facto standard OS for embedded sensor networks. The ability to quickly build large and complex systems raises novel challenges in isolating independent subsystems from one another in the absence of virtualization. TinyOS's component and concurrency models provide greater program structure for run-time checks and compile-time verification. Co-designing the language and OS in parallel allows us to not only add language primitives to help analysis, but also to design the OS so that it is more checkable.

Stanford Wireless Access Network (SWAN)

The Stanford Wireless Access Network (SWAN) project aims to study and implement existing techniques for setting up mesh networks and research into extending those techniques for improved performance. Experiments have shown that although current protocols are able to form routes and route data in the network, the performance falls below what would be expected of a production network. Especially with multiple streams active, delivery reliability and performance are unacceptable for an office environment. Further, experiments on SWAN also show that existing rate selection algorithms fail miserably in mesh networks. A lot of the times, self interference can lead to bad link estimates and cause transmitters to switch to the lowest transmission rate, thus wasting valuable channel time and reducing throughput. The SWAN project conducts research into improving routing, link estimation and adaptive transmit parameter selection for creating a production class wireless mesh network