Wireless communication has become more popular over the last decade. Although
there are many advantages to use wireless over fixed line systems, there is a major
disadvantage, which is a high transmission error rate in a temporal and permanent nois
y
environment. There are techniques to reduce effectiveness off transmission errors in
wireless communications. We have discussed in this paper. Many methods and techniques
have been implementing to deal and resist errors (by increasing transmission power,
switching modulation scheme) as well as evaluation the wireless connection performance
taking into account many factors.
This works aims to study the performance of the mobile system via studying the
effects of adaptive modulation technique on the data rate. Fuzzy logic technique is used as
a tool to analyze the data rate of the downlink connection depending on type
of
modulation, coverage quality and the distant between the receiver and the transmitter. For
parameters were considered as input parameters for the fuzzy logic system mainly are:
power of the station, quality of coverage, the type of modulation technique and the signal
to interface noise ratio. One parameter is used as an output of the fuzzy system which is
spectrum efficiency in bit per second per hertz. Analytical study to select the optimal data
rates for different modulation techniques will be considered. Additionally, studying the
input and output memberships of the data rate parameters using fuzzy logic will be
explained. Keywords: Data rate, downlink, signal to noise ratio, modulation type, Fuzzy
logic, spectrum efficiency.
The effect of thermal noise and shot noise on the receiver sensitivity in a digital
optical communication system will be studied and analyzed. Also, the positive and
negative effects of Parameters on the receiver sensitivity will be highlighted. Th
e
programming tools (MATLAB) is used to study the relationship between the receiver
sensitivity and bit rate. It showed that the shot-noise-limited receiver sensitivity is much
better than the thermal -noise-limited receiver sensitivity with best 30dB. The study also
provided an explanation for the preference of optical detector (APD) compared to that in
(PIN) optical detector from sensitivity side due to its internal gain, this can be achieved
when the thermal noise is dominant. However, the preference of optical detector(PIN) will
be better in case of shot noise is dominant.
Analyzed results show that there is a significant improvement in the shot-noiselimited
receiver sensitivity for high quantum efficiency and high wavelength. However, the
sensitivity is deteriorated to get a lower error rate. The thermal -noise-limited receiver
sensitivity showed an improving by increasing the responsivity and the load resistance.
However, it decreases by increasing the number of noise and the error rate.
Speech denoising is a field of engineering that studies techniques used to recover the
original signal from the noisy signal corrupted with different types of noise, such as
broadband noise and narrowband noise, and other types present in environme
nt, but the
spectral subtraction technique consider the most prominent in this area .
In this search we will discuss the parameters impact of the modified spectral
subtraction algorithm and the time window length in the enhancement of speech that
corrupted with broadband noise. We done the study and determine the ideal parameters
values and the ideal window length with different values for the signal -to-noise ratio SNR
for noisy speech and we discuss 18 case for each value. We done
the simulation using MATLAB software and the results were compared based on
improving the value of SNR for each case .
In this project we study wavelet and wavelet transform, and the possibility of its employment in the processing and analysis of the speech signal in order to enhance the signal and remove noise of it. We will present different algorithms that depend
on the wavelet transform and the mechanism to apply them in order to get rid of noise in the speech, and compare the results of the application of these algorithms with some traditional algorithms that are used to enhance the speech.
This research aims to study the effects of weaknesses on the performance of the existing network such as the impact of Attenuation and crosstalk on the data transfer, and it presents also the improvements of the standards of DSL systems to achieve th
e maximum transition rates in order to have greater speed in the installation of high-speed subscriber lines.
It also offers a new range of services to communication companies through the provision of new xDSL technologies in the near future. Thus, it enables its customers access to broadband services and provides tips for the Syrian Telecommunications Company in their choice of systems.
This research analyses the essence of the techniques and the strengths and weaknesses of the criteria for All Digital Mode digital subscriber line mentioned in Annex A and for higher upstream digital subscriber line mentioned in Annex M. It also includes an analytical study of the damping and crosstalk to show how to consider any criteria as a better choice.
Finally, It includes programmatically represented simulation of the signal which is sent over transmission lines under the influence of the studied factors.
The turbine control purpose is to achieve the maximum limit of wind power,
associated with reducing the mechanical loads. The current control techniques do not take
into consideration the dynamical side of wind and turbine, which leads to power los
s. To
improve the effectiveness of the
nonlinear controllers, we can derive the nonlinear feedback controllers for static and
dynamic conditions in order to reach the wind speed estimator. Then we can test the
controllers by a mathematical model applied on the wind turbine simulator, with
disturbances and noise. The results have shown important improvements in comparison
with the current used controllers.
This work aims to analyze the performance of the microwave radio link’s parameters
used to connect different systems and intra systems. Fuzzy logic technique is used to study
the difficulties of the radio link’s parameters based on type of modulati
on, and distance
between the receiver and transmitter. Four parameters are used as an input parameters for
the fuzzy logic system mainly: required power, the length of the microwave radio link,
modulation type and the signal to noise ratio(S/N). The output parameter is determined to
be the microwave link capacity.
Analytical study to select the optimal microwave radio link parameters to examine
the efficiency of the radio link capacity will be shown. Additionally, studying the input and
output memberships of the microwave radio link parameters using fuzzy logic will be
explained.
The study suggests a new approach to segment the ultrasound
uterus images to obtain the fetus region. The approach consists of
three stages. The first includes the preprocessing in which the
speckle noise is removed from the ultrasound images depe
nding on
sequential filtering of Gabor filter and median filter. Second, an
improved active shape contour independent of edges is applied to
segment the uterus images. The last stage is the post processing
which depends on the morphological operation to eliminate the
undesired region and obtain the region of interest (fetus).
The designed system has been tested by means of medical database
of ultrasound uterus images downloaded from the ULTRASCAN
CENTRE site in Kaloor (India). The experimental tests show that
the proposed sequential filtering technique improves the active
shape contour algorithm performance significantly, so the system
segment the uterus images correctly even in the presence of speckle
noise.
Over the last few years, the radio frequency (RF) technology has experienced an exponential growth. With the requirement for more integration, new RF wireless architectures are needed. One of the most critical blocks in a wireless transceiver is the
oscillator. Phase noise from radio frequency (RF) oscillators is one of the major limiting factors affecting wireless transceiver performance. Phase noise directly affects short-term frequency stability, Bit-Error-Rate (BER), and phase-locked loop adjacent-channel interference.
