2 research outputs found
CH Selection via Adaptive Threshold Design Aligned on Network Energy
Energy consumption in Wireless Sensor Networks (WSN) involving multiple sensor nodes is a crucial parameter in many applications like smart healthcare systems, home automation, environmental monitoring, and industrial use. Hence, an energy-efficient cluster-head (CH) selection strategy is imperative in a WSN to improve network performance. So to balance the harsh conditions in the network with fast changes in the energy dynamics, a novel energy-efficient adaptive fuzzy-based CH selection approach is projected. Extensive simulations exploited various real-time scenarios, such as varying the optimal position of the location of the base station and network energy. Additionally, the results showed an improved performance in the throughput (46%) and energy consumption (66%), which demonstrated the robustness and efficacy of the proposed model for the future designs of WSN applications
Novel power amplifier design using non-linear microwave characterisation and measurement techniques
This thesis, addresses some aspects of the well-known, problem, experienced by designer of
radio frequency power amplifiers (RFPA): the efficiency/linearity trade-off. The thesis is
focused on finding and documenting solution to linearity problem than can be used to
advance the performance of radio frequency (RF) and microwave systems used by the
wireless communication industry. The research work, this was undertaken by performing a
detailed investigation of the behaviour of transistors, under complex modulation, when
subjected to time varying baseband signals at their output terminal: This is what in this thesis
will be referred to as ābaseband injectionā. To undertake this study a new approach to the
characterisation of non-linear devices (NLD) in the radio frequency (RF) region, such as
transistors, designated as device-under-test (DUT), subjected to time varying baseband
signals at its output terminal, was implemented. The study was focused on transistors that are
used in implementing RF power amplifiers (RFPA) for base station applications. The nonlinear
device under test (NL-DUT) is a generalisation to include transistors and other nonlinear
devices under test. Throughout this thesis, transistors will be referred to as ādeviceā or
āradio frequency power amplifier (RFPA) deviceā. During baseband injection investigations
the device is perturbed by multi-tone modulated RF signals of different complexities. The
wireless communication industry is very familiar with these kinds of devices and signals.
Also familiar to the industry are the effects that arise when these kind of signal perturb these
devices, such as inter-modulation distortion and linearity, power consumption/dissipation and
efficiency, spectral re-growth and spectral efficiency, memory effects and trapping effects.
While the concept of using baseband injection to linearize RFPAs is not new the
mathematical framework introduced and applied in this work is novel. This novel approach
NOVEL POWER AMPLIFIER DESIGN USING NON-LINEAR MICROWAVE CHARACTERISATION AND MEASUREMENT TECHNIQUES CARDIFF UNIVERISTY - UK
ABSTRACT vi
has provided new insight to this very complex problem and highlighted solutions to how it
could be a usable technique in practical amplifiers.
In this thesis a very rigorous and complex investigative mathematical and measurement
analysis on RFPA response to applied complex stimulus in a special domain called the
envelope domain was conducted. A novel generic formulation that can āengineerā signal
waveforms by using special control keys with which to provide solution to some of the
problems highlighted above is presented.
The formulation is based on specific background principles, identified from the result of both
mathematical theoretical analysis and detailed experimental device characterisation