الفهرس 
INTRODUCTION TO WIRELESS SENSOR NETWORKSOnly 14 pages are availabe for public view
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Abstract
The usage of wireless links in our everyday life is increasing
dramatically. One example of this is the emerging field of wireless sensor
networks (WSN). This new field presents many opportunities and
challenges. One particularly difficult aspect of wireless sensing is the
implementation of the radio link.
This dissertation demonstrates the design of a low power transmitter
for wireless sensor networks (WSN). It begins with an introduction to
WSN, their applications and requirements. Current state-of-the-art
transmitter implementations for WSN transmitter are presented and
compared favoring ultra-wide band impulse radio (UWB-IR) as an
enabling technology for low power radio links. The IEEE 802.15.4a
standard for UWB-IR is presented and design constrains are extracted.
Next, the dissertation presents the design of a standard compliant
UWB-IR transmitter. The system architecture is explained, it is
subdivided into two major blocks: a digital frequency locked loop (FLL)
and a pulse generation, modulation and shaping circuit. The FLL is used
for RF carrier generation between 3 and 5GHz, it includes a digitally
controlled oscillator, a high frequency divider and an early-late frequency
detector. The pulse generation and shaping circuit shapes the RF carrier
into UWB pulses using a triangular pulse generator and a pulse shaping mixer. These main blocks of the transmitter are analyzed, designed in
O.13}ll11 CMOS technology, and Spectre simulation results are shown.
Exploiting the inherently low duty cycle of UWB signal, low power
operation was achieved by turning-off most of the transmitter blocks
between two communication bursts. Operating at a data rate of 1Mbps,
the power consumption was only 1.44m W.
Key words: low power transmitter, wireless sensor networks, ultra-
wide band impulse radio (UWB-lR), IEEE 802.l5.4a standard, digitally
controlled oscillators, pulse shaping mixer.