Low-Complexity and High-Throughput Protocols for Wireless Sensor Networks

by Chongjing Chen

Location: Engineering Hall 2210

Date and Time: November 18, 2009 2:00pm

Committee:
Prof. Pai H. Chou (Chair)
Prof. Stephen Jenks
Prof. Rainer Doemer

Abstract:
Wireless technologies have enabled mobility and convenience by eliminating cumbersome wires. Wireless sensor nodes must be made small and low power without sacri?cing performance. In addition to task scheduling, the densely distributed wireless sensor nodes must run communication protocols to achieve better utilization and reliable communication. While many researchers work on wireless sensor networks that are densely distributed, they assume low duty cycling and trivial data rate. Unfortunately, this is a great mismatch with many real-world applications that require the high data rate. Furthermore, most wireless communication protocols are too complicated to be used on compact wireless sensor nodes with limited RAM and ROM.

To address these issues, we propose a lightweight multiple access control protocol to enable relatively high data rate and densely distributed deployment. It can achieve reliable communication on resource-constrained wireless sensor nodes and minimizes the protocol complexity to reduce the memory footprint. The protocol can also work under high utilization of air bandwidth without collision. While civil engineers are concerned about the sampling rate at 100 Hz for structure monitoring, our system with this protocol can scale up to 50 wireless sensor nodes and stream real-time data in the same frequency channel at 100 Hz sampling rate. We also propose a compact, multi-channel protocol with high scalability and small memory footprint. This multiple access control protocol enables wireless sensor nodes to transmit sensing data over multiple frequency channels to achieve a higher throughput than a system with only a single frequency channel. We integrate our protocol with a giant tiled display system, HIPerWall, to show the real-time sensing data at a high resolution without downsampling. Last, we perform a thorough evaluation to study the channel characteristics of a wearable wireless sensor node. We vary several di?erent parameters, the RF transmission power, distance, height, and angle to observe the packet loss rates. These experimental results can be used for constructing a more reliable wireless communication for wireless sensor networks.