Date of Award

12-2008

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Electrical Engineering

Advisor

Wang, Kuang Ching

Committee Member

Russell , Harlan B

Committee Member

Huang , Yong

Abstract

Wireless sensors are increasingly adopted in manufacturing and vehicular systems for monitoring critical components under continuous operation. Many such components move rapidly and frequently in metallic containments with challenging radio propagation characteristics.
For wireless sensors mounted on rotating structures, previous studies identified an eminent increase in packet transmission errors at higher rotation speeds. Such errors were found to occur at specific locations around the rotating spindle's periphery and such locations depended sensitively on sensor location and surrounding geometry. This thesis presents a systematic study of the expected packet error rates due to such errors, and analytically derives the first transmission error rate for a given system. Simulations done on C++ are used to characterize the error region properties. A transmission error avoidance approach based on on-line error pattern inference and packet transmission time control for IEEE 802.15.4 compatible sensor radios is proposed.
The transmission avoidance scheme has two phases: error identification phase to determine the error characteristics of the system and the operational phase to avoid errors. Simulation studies showed a 50% error reduction and up to 75% throughput increase for a rotation system with four symmetric 4¼ wide error zones with 100% BER inside the error region and 0% BER outside the error region. Higher throughput gains for higher rate and larger size transmissions were also noticed for this system. Simulations also show that the throughput decreases when the packet size duration is greater than the separation between the error zones

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