Zeng, Yu (2010) Adaptive modulation schemes for optical wireless communication systems. PhD thesis, University of Warwick.

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Abstract

High-speed wireless optical communication links have become more popular for
personal mobile applications. This is a consequence of the increasing demand
from the personal information service boom. Compared to the radio frequency
domain, optical wireless communication offers much higher speeds and bit rates
per unit power consumption. As stated by the official infrared standard IrDA
optical communication enjoys much lower power consumption than Bluetooth,
with an inherent security feature while in Line of Sight (LOS) applications. There
are also drawbacks such as the infrared radiation cannot penetrate walls as radio
frequencies do and interference from the background contribute to the channel
dispersions.
Focus on the modulation aspects of the optical wireless communication, this
thesis try to improve the channel immunity by utilising optimised modulation to
the channel. Modulation schemes such as on off keying (OOK), pulse amplitude
modulation (PAM) and pulse position modulation (PPM) and pulse position and
amplitude modulation PAPM schemes have been validated. The combined power
and bandwidth requirements suggest that the adaptive modulation schemes can
provide reliability when deployed in a real time channel, resulting in improved
system performance.
As a result, an adaptive modulation technique is proposed. Extensive simulations
of severe noise distraction have been carried out to validate the new scheme. The
simulation results indicate that the new scheme can provide increased immunity
against channel noise fluctuation at a relatively low complexity. The scheme
obtained formed a basis to support reliable mobile optical wireless
communication applications.
The adaptive scheme also takes the real time channel conditions into account,
which is different from existing schemes. Guaranteed system performance can be
secured without compromising power and bandwidth efficiency. This is also a
new approach to realise reliable optical wireless links. Fuzzy logic control
module has been developed to match the adaptive pattern.

Item Type:	Thesis (PhD)
Subjects:	T Technology > TK Electrical engineering. Electronics Nuclear engineering
Library of Congress Subject Headings (LCSH):	Optical communications, Wireless communication systems, Modulation (Electronics)
Official Date:	April 2010
Dates:	Date Event April 2010 Submitted
Institution:	University of Warwick
Theses Department:	School of Engineering
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Green, Roger J. ; Leeson, Mark
Extent:	xvii, 228 leaves : ill., charts
Language:	eng

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