31 research outputs found
Comparison between scheduling techniques in long term evolution
Long-Term Evolution (LTE) is a recently evolving technology
characterized by very high speed data rate that allows users to access internet through
their mobile as well as through other electronic devices. Such technology is intended to
support variety of IP-based heterogeneous traffic types. Traffic scheduling plays an
important role in LTE technology by assigning the shared resources among users in the
most efficient manner. This paper discusses the performance of three types of scheduling
algorithms namely: Round Robin, best Channel Quality Indicator (CQI) and Proportional
Fair (PF) schedulers representing the extreme cases in scheduling. The scheduling
algorithms performances on the downlink were measured in terms of throughput and
block error rate using a MATLAB-based system level simulation. Results indicate that
the best CQI algorithm outperforms other algorithms in terms of throughput levels but on
the expense of fairness to other users suffering from bad channel conditions
Review of SCADA systems and IoT honeypots
Internet of Things (IoT) is a massive technology
that is being improved day by day. It connects different types
of devices to the internet so that they can interchange data. The
most feild that has been improved by implementing IoTโs
technology is Supervisory Control and Data Acquisition
(SCADA) Systems, or Industrial Control Systems (ICS). The
application of these systems is to be used in controlling
different elements that is connected to it (sensors, devices, and
machines). However, connecting different types of devices of
different physical circuitry and different communication
technology, together raises various security issues that has been
a place of concern for years. A famous technique that has been
implemented in the field of security to further study Cyber
Attacks, its causes, and effects is Honeypots. The Aim from this
paper is to categorize Cyber -physical attacks and their effects,
study SCADA/ICS systemsโ architecture, highlight its security
weaknesses, and how Cyber/Physical attacks make use of these
weaknesses. Finally, a break down Honeypots and understand
its implementation and effectiveness in the Field of Cyber
Security
Maximum-Largest Weighted Delay First Algorithm for Heterogeneous Traffic in 4G Networks
Real time applications with strict QoS like delay sensitive applications require an advanced technology to adopt them. This is where Long Term Evolution-Advanced (LTE-A) fulfills this requirement. With this ever evolving technology the need for improvements is required. Packet scheduling is one of the important key features of LTE-A, where it dictates user selection and transmission of those userโs packets based on the priority of the users to reach the receiver correctly. Packet scheduling is one mean to achieve those QoS requirements that real-time applications require. Such algorithms are HARQ Aware Scheduling Algorithm (HAS), Retransmission Aware Proportional Fair Algorithm (RAPF), Chase Combining Based Max C/I Scheduling and Maximum- Largest WeightedDealy First algorithm (M-LWDF). In this paper, M-LWDF is one of the best algorithms in LTE-A which was chosen for further investigated to support QoS in high mobility environment. Packet Loss Ratio (PLR), and Mean User Throughput performance measures were used to validate the performance of M-LWDF algorithm against other algorithms using similar mobile environment. Simulation results indicate the capability of M-LWDF algorithm within the threshold of the performance measures against other benchmarks where it has demonstrated more efficiency to support and improve the performance of real-time multimedia traffic
A Packet Scheduling Scheme for Improving Real-time Applications Performance in Downlink LTEโadvanced
Quality of Service based packet scheduling is a key-feature of LTE-A mandating selection and transmission of individual user packets based on their priority. HARQ Aware Scheduling, Retransmission Aware Proportional Fair, Chase Combining Based Max C/I Scheduling and Maximum- Largest Weighted First (M-LWDF) are popular Packet Scheduling Algorithms (PSAs) developed to meet QoS requirements. In highly erroneous LTE-A cannel, M-LWDF is considered to be one of best PSA. To validate the performance of M-LWDF for the LTE-A channel, Mean User Throughout, and Fairness performance measures were evaluated for 3 different PSAs designed based on M-LWDF algorithm in this paper. A C++ based simulation results indicate the superiority of the PSA3 algorithm within the threshold of the performance measures against benchmarks. It has shown more efficiency and the performance of RTA traffic was enhanced. Results show that PSA3 is superior to its benchmark PSA2 by 12% in Mean User Throughput and 11% in Fairness. PSA2 performed the worst because it prioritizes new users and it allocated all available RBs to the scheduled user leaving the rest to wait in the buffer. PSA3 maintians good Mean User Throughput and fairnessdue to scheduling each user on its RB which leads to multi-user diversity
Maximum-largest weighted delay first algorithm for heterogeneous traffic in 4G networks
Real time applications with strict QoS like delay sensitive applications require an advanced technology to adopt them. This is where Long Term Evolution-Advanced (LTE-A) fulfills this requirement. With this ever evolving technology the need for improvements is required. Packet scheduling is one of the important key features of LTE-A, where it dictates user selection and transmission of those userโs packets based on the priority of the users to reach the receiver correctly. Packet scheduling is one mean to achieve those QoS requirements that real-time applications require. Such algorithms are HARQ Aware Scheduling Algorithm (HAS), Retransmission Aware Proportional Fair Algorithm (RAPF), Chase Combining Based Max C/I Scheduling and Maximum- Largest WeightedDealy First algorithm (M-LWDF). In this paper, M-LWDF is one of the best algorithms in LTE-A which was chosen for further investigated to support QoS in high mobility environment. Packet Loss Ratio (PLR), and Mean User Throughput performance measures were used to validate the performance of M-LWDF algorithm against other algorithms using similar mobile environment. Simulation results indicate the capability of M-LWDF algorithm within the threshold of the performance measures against other benchmarks where it has demonstrated more efficiency to support and improve the performance of real-time multimedia traffic
Design an ultra-wideband modified wilkinson power divider fed-by balanced antipodal vivaldi antenna array for imaging applications
In this paper, design of compact and modified geometrical structure of 1-to-4 way ultra-wideband Wilkinson power divider used as a feeding network for 4-element of balanced antipodal Vivaldi antenna (BAVA) array has introduced. The proposed Wilkinson power divider has been designed and printed on low-cost Epoxy laminate substrate FR4 along
with the thickness of 1.6mm and relative permittivity of ษr =4.3 respectively. The transformation of power divider network which are based on bent corners as a replacement of sharp corners or edges used for the decrement in unintended radiation and employing a single radial stub on
each branch to encounter the antenna-specifications. Further some adjustments in the dimension of stubs matching in order to increase the reflection of the power divider network.
The design presents the model of a power divider and maintains an equal power splitting at different ports with practical insertion loss and conventional return loss below -10dB. The reasonable impedance matching has achieved at every single port with acceptable isolation performance values over the (3-to-10 GHz) frequency range. The divider as well as antenna elements design and its optimization are practicable via computer simulation technology (CST)
simulation software. The experimental results are revealed to encounter the array-specifications under ultra-wideband frequency range
Design and analysis of 1-to-4 Wilkinson power divider for antenna array feeding network
In this paper, A Novel 1 to 4 modified Wilkinson
power divider operating over the frequency range of (3
GHz to 8 GHz) is proposed. The design perception of the
proposed divider based on two different stages and printed
on FR4 (Epoxy laminate material) with the thickness of
1.57mm and ฯตr =4.3 respectively. The modified design of
this power divider including curved corners instead of the
sharp edges and some modification in the length of
matching stubs. In addition, this paper contain the power
divider with equal power split at all ports, reasonable
insertion loss, acceptable return loss below -10 dB, good
impedance matching at all ports and satisfactory isolation
performance has been obtained over the mentioned
frequency range. The design concept and optimization
development is practicable through CST simulation
software
Design and parametric evaluation of UWB antenna for array arrangement
This paper has introduced the concept of UWB antenna in array arrangements. The four elements of Balance Antipodal Vivaldi Antenna (BAVA) has been used for planar and H-plane array configuration in this research. Each single element of BAVA Antenna is printed on the glass-reinforced epoxy laminate material (FR4) along an overall thickness of 1.57mm and ฮตr=4.3 respectively. The optimized measurement of each particular element is 60.75mm x 66mm approximatel. Further the parametric evaluation of four BAVA elements in different planes has been observed in this paper. The placement of array elements has almost coverd entire UWB frequency range and appropriate reflection coefficient which is better than -10dB has been established in both combinations. According to simulation results, the array elements in planar arrangement presenting a suitable reflection and works well at 3.2GHz frequency while the arrangement in H-plane the array elements works well at 7GHz of frequency. In planar arrangement, the operating frequency of antenna elements is shifting as results of the distance among inter elements which increase in wavelength. In H-plane arrangement an antenna elements generate additional gain up to 10.2 dB with good radiation patterns as compared to the planar plane. The CSTMWS simulation software has been used for antenna structural design and parametric verification
Effects of humidity on sand and dust storm attenuation predictions based on 14 GHz measurement
Several models were proposed to predict the attenuation of microwave signals due to sand and dust storms. Those models were developed based on theoretical assumptions like Rayleigh approximation, Mie equations or numerical methods. This paper presents a comparison between attenuation predicted by three different theoretical models with measured attenuation at 14 GHz. Dielectric constant of dust particles is one of the important parameter in prediction models. This constant is estimated from measured dust samples and is utilized for predictions. All models are found largely underestimating the measurement. Humidity is also monitored and has been observed higher during dust storm. Hence dielectric constants are re-estimated with relative humidity conditions using available conversion model. The prediction has a great impact of humidity and predicted attenuations are found much higher in humid than dry dust condition. However, all models underestimate the measurement even considering 100% of relative humidity. Hence it is recommended to investigate the models by considering humidity and other environmental factors that change during dust storm
Comparative analysis of UWB balance Antipodal Vivaldi Antenna for array configuration
In this paper, an Ultra-wideband Balance
Antipodal Vivaldi Antenna in planar and h-plane array
configuration is presented. The comparison of four elements of
BAVA array in both planes has been observed. Each element
of an antenna printed on the glass-reinforced epoxy laminate
material (FR4) with a thickness of 1.5mm and relative
permittivity of 4.3. The dimension of every single element is
60.75mm x 66mm approximately. The array elements of both
planes almost cover the whole UWB frequency range with the
reflection coefficient of -10dB. Based on the simulation results,
the array elements in planar configuration showing good
reflection and works well at 3.2GHz frequency while the
configuration in h-plane the array elements works well at
7GHz of frequency. In planar configuration, the operating
frequency of antenna elements is shifting as a result of the
distance between inter elements which intensification in
wavelength. The array elements in h-plane produce more gain
up to 10.2 dB with good radiation patterns as compared to the
planar plane. The antenna design and optimization
development are verified using CST simulation software