|dc.description.abstract||The potential for collaborative, robust networks of wireless sensors has attracted a great deal of research attention. For the most part, this is due to the compelling applications that wireless sensor networks will enable. Location sensing, environmental observation and surveillance, medical monitoring and a lot other applications are all gaining interest. However, wireless sensor network poses a large number of challenges. Among all, one of the most important challenges is design sensor networks that have long network lifetime, which will become especially difficult due to the energy-constrained nature of the sensor nodes. In this thesis, we focus on physical and application layer issues and approaches to design algorithms.
Virtual Multiple-Input Multiple-Output (MIMO) structure is very attractive to wireless sensor networks due to its huge diversity gain and potential ability to save energy. With channel state information at transmitter side, water-filling algorithm can be applied to optimize the power allocation in each sub-channel of the MIMO system based on the estimated channel matrix, so as to maximize the channel capacity. In reality, however, both the estimation error and the delay will be introduced when estimate the channel. We will investigate how the estimation error will impact the optimal water-filling strategy in wireless sensor networks.
A hybrid FH/TH-PPMUWB system is proposed for Wireless Sensor Networks to confront the hostile environment. An exact analysis is also derived to precisely calculate the bit error rates for both Additive White Gaussian Noise channel and path-loss channel in the presence of multitone/pulse (tone in frequency domain and pulse in time domain) interference and Multi-User Interference.
Two event-detection approaches were proposed, including double sliding scheme and hybrid approach based on Fuzzy Logic System. We also proposed to use type-2 Fuzzy logic system to forecast the sensed signal and the event.
We theoretically proved the data from adjacent sensor nodes have cross-similarity. Proposed to use Singular-Value-QR Decomposition(SVD-QR) to reduce the redundancy in wireless sensor networks to save energy and prolong the network lifetime.||en_US