The document analyzes the performance of IEEE 802.16d under the Stanford University Interim (SUI) channel model. It investigates the bit error rate of IEEE 802.16d using different SUI channel models and digital modulations like BPSK and QPSK. The results show the BER performance for different SUI channel models and modulations.
Radio over fiber system based on a hybrid link for next generation of optical...IJECEIAES
Radio over fiber technology will play an important role in solving problems facing wireless technology. Envisaging a global village, people could transmit and receive “anytime, anywhere, and anything”. In addition, the explosive growth in internet applications such as the World Wide Web, demonstrates the tremendous increase in bandwidth and low power that the coming world of multimedia interactive applications will require from future networks. ROF technology uses multicarrier modulation like orthogonal frequency division multiplexing (OFDM), which provides an opportunity of having an increased in bandwidth together with an affordable cost and this idea has recently become a suitable topic for many research works. On the other hand, SAC-OCDMA (Spectral Amplitude Coding Optical Code Division Multiple Access) technique is able to enhance the data rate of system and increase the number of user. In this paper we introduce a ROF link using a hybrid OFDM/SAC-OCDMA technique.
Implementation and Study of Universal Filtered Multi Carrier under Carrier Fr...Editor IJAIEM
Sathiyapriya N.S
PG Student, Dept. of ECE, Periyar Maniammai University Thanjavur, Tamilnadu, India
ABSTRACT
OFDM is a matured technology and applied in various wireless standards. However they are not suitable for Uplink and this
technology is replaced by SC FDMA in 4G standards. Similarly Universal Filtered Multicarrier Communication (UFMC) is
another suitable technology for Multi user Uplink and for applications like cognitive radio. UFMC is a new, non-orthogonal,
waveform designed by Alcatel Lucent Labs which provide a much more efficient way of enabling networks to serve both
broadband users and very narrowband “short data” devices such as any embedded sensor or M2M module. In UFMC the
filtering of waveform is done on a group of subcarriers. In OFDM it is done on the whole subcarriers together. This reduces
the side lobe levels, inters carrier interference (ICI) and requires reduced filter length. Moreover Internet-of-Things where
Machine-Machine communication and applications where very tight response in time requirements are needed, OFDM
miserably fails. We examine impact of carrier frequency offset on the performance of the proposed scheme and compare the
results performance of cyclic prefix based orthogonal frequency division multiplexing(CP-OFDM) system.-
Key words: ICI,CFO,OFDM,UFMC
Performance Analysis of OFDM in Combating Multipath FadingIOSR Journals
Mobile Communication system has been on high rampage for high data transmission over wireless
medium with various challenges caused by the transmission Channel. OFDM is been discovered in recent years
to deal with this problems because of its ability to elegantly cope with multipath interference. This paper
investigates the performance of different modulation schemes using M-ary Phase Shift Keying (M-PSK) and Mary
Quadrature Amplitude Modulation (M-QAM) in information transmission with OFDM technique over Ideal
channel AWGN and worst channel Rayleigh Fading channel in terms of Bits Error Rate (BER). Analysis was
made for different types of modulation schemes BPSK, QPSK, 4-QAM and 16-QAM gray coded bit mapping.
Also, a feasibility of OFDM been used to combat multipath fading was analyzed with comparison between a
single carrier technique and OFDM multicarrier technique. Variation between SNR results with respect to BER
is plotted to show the trade off differences between the modulation schemes with the result showing that OFDM
allows data transmission with minimal error over fading channel than a Single Carrier
Rapid developments in modern wireless communication permit the trade of spectrum scarcity. Higher data rate and wider bandwidth emerge the development in growing demand of wireless communication system. The innovative solution for the spectrum scarcity is cognitive radio (CR). Cognitive radio is the significant technology used to utilize the spectrum effectively. The important aspect of CR is sensing the spectrum band and detects the presence or absence of the primary user in the licensed band. Moreover, another serious issue in next generation (5G) wireless communication is to decide the less complex 5G waveform candidate for achieving higher data rate, low latency and better spectral efficiency. Universal filtered multi-carrier (UFMC) is one of the noticeable waveform candidates for 5G and its applications. In this article, we investigate the spectrum sensing methods in multi-carrier transmission for cognitive radio network applications. Especially, we integrate the sensing algorithm into UFMC transceiver to analyze the spectral efficiency, higher data rates and system complexity. Through the simulation results, we prove that the UFMC based cognitive radio applications outperform the existing Orthogonal Frequency Division Multiplexing (OFDM) based CR applications.
RECONFIGURABLE OPTICAL ADD AND DROP MULTIPLEXERS A REVIEWecijjournal
Optical multiplexing is the key function of a WDM network and reliable method for data transport networks. WDM networks configured as rings/mesh along with Optical Add-Drop Multiplexers supports added flexibility, simplicity and augment the spectral efficiency. Further enhancement achieved with Reconfigurable OADM architectures, growing briskly along with automatic network management, let the transport network to acclimatize with dynamically varying environment and flexibly respond to the transport network changes. It permits single or many wavelengths to be added and/or dropped from a
transport fiber without optical-to-electrical-to-optical domain translation. Presently ROADM technology
has revolutionized optical networking and an inseparable part of modern optical communication offering huge bandwidth for data transport at minimum expense. In this view the article presents comprehensive study for numerous generations of ROADM and their architecture and persistent development
IOSR Journal of Electronics and Communication Engineering(IOSR-JECE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of electronics and communication engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in electronics and communication engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Radio over fiber system based on a hybrid link for next generation of optical...IJECEIAES
Radio over fiber technology will play an important role in solving problems facing wireless technology. Envisaging a global village, people could transmit and receive “anytime, anywhere, and anything”. In addition, the explosive growth in internet applications such as the World Wide Web, demonstrates the tremendous increase in bandwidth and low power that the coming world of multimedia interactive applications will require from future networks. ROF technology uses multicarrier modulation like orthogonal frequency division multiplexing (OFDM), which provides an opportunity of having an increased in bandwidth together with an affordable cost and this idea has recently become a suitable topic for many research works. On the other hand, SAC-OCDMA (Spectral Amplitude Coding Optical Code Division Multiple Access) technique is able to enhance the data rate of system and increase the number of user. In this paper we introduce a ROF link using a hybrid OFDM/SAC-OCDMA technique.
Implementation and Study of Universal Filtered Multi Carrier under Carrier Fr...Editor IJAIEM
Sathiyapriya N.S
PG Student, Dept. of ECE, Periyar Maniammai University Thanjavur, Tamilnadu, India
ABSTRACT
OFDM is a matured technology and applied in various wireless standards. However they are not suitable for Uplink and this
technology is replaced by SC FDMA in 4G standards. Similarly Universal Filtered Multicarrier Communication (UFMC) is
another suitable technology for Multi user Uplink and for applications like cognitive radio. UFMC is a new, non-orthogonal,
waveform designed by Alcatel Lucent Labs which provide a much more efficient way of enabling networks to serve both
broadband users and very narrowband “short data” devices such as any embedded sensor or M2M module. In UFMC the
filtering of waveform is done on a group of subcarriers. In OFDM it is done on the whole subcarriers together. This reduces
the side lobe levels, inters carrier interference (ICI) and requires reduced filter length. Moreover Internet-of-Things where
Machine-Machine communication and applications where very tight response in time requirements are needed, OFDM
miserably fails. We examine impact of carrier frequency offset on the performance of the proposed scheme and compare the
results performance of cyclic prefix based orthogonal frequency division multiplexing(CP-OFDM) system.-
Key words: ICI,CFO,OFDM,UFMC
Performance Analysis of OFDM in Combating Multipath FadingIOSR Journals
Mobile Communication system has been on high rampage for high data transmission over wireless
medium with various challenges caused by the transmission Channel. OFDM is been discovered in recent years
to deal with this problems because of its ability to elegantly cope with multipath interference. This paper
investigates the performance of different modulation schemes using M-ary Phase Shift Keying (M-PSK) and Mary
Quadrature Amplitude Modulation (M-QAM) in information transmission with OFDM technique over Ideal
channel AWGN and worst channel Rayleigh Fading channel in terms of Bits Error Rate (BER). Analysis was
made for different types of modulation schemes BPSK, QPSK, 4-QAM and 16-QAM gray coded bit mapping.
Also, a feasibility of OFDM been used to combat multipath fading was analyzed with comparison between a
single carrier technique and OFDM multicarrier technique. Variation between SNR results with respect to BER
is plotted to show the trade off differences between the modulation schemes with the result showing that OFDM
allows data transmission with minimal error over fading channel than a Single Carrier
Rapid developments in modern wireless communication permit the trade of spectrum scarcity. Higher data rate and wider bandwidth emerge the development in growing demand of wireless communication system. The innovative solution for the spectrum scarcity is cognitive radio (CR). Cognitive radio is the significant technology used to utilize the spectrum effectively. The important aspect of CR is sensing the spectrum band and detects the presence or absence of the primary user in the licensed band. Moreover, another serious issue in next generation (5G) wireless communication is to decide the less complex 5G waveform candidate for achieving higher data rate, low latency and better spectral efficiency. Universal filtered multi-carrier (UFMC) is one of the noticeable waveform candidates for 5G and its applications. In this article, we investigate the spectrum sensing methods in multi-carrier transmission for cognitive radio network applications. Especially, we integrate the sensing algorithm into UFMC transceiver to analyze the spectral efficiency, higher data rates and system complexity. Through the simulation results, we prove that the UFMC based cognitive radio applications outperform the existing Orthogonal Frequency Division Multiplexing (OFDM) based CR applications.
RECONFIGURABLE OPTICAL ADD AND DROP MULTIPLEXERS A REVIEWecijjournal
Optical multiplexing is the key function of a WDM network and reliable method for data transport networks. WDM networks configured as rings/mesh along with Optical Add-Drop Multiplexers supports added flexibility, simplicity and augment the spectral efficiency. Further enhancement achieved with Reconfigurable OADM architectures, growing briskly along with automatic network management, let the transport network to acclimatize with dynamically varying environment and flexibly respond to the transport network changes. It permits single or many wavelengths to be added and/or dropped from a
transport fiber without optical-to-electrical-to-optical domain translation. Presently ROADM technology
has revolutionized optical networking and an inseparable part of modern optical communication offering huge bandwidth for data transport at minimum expense. In this view the article presents comprehensive study for numerous generations of ROADM and their architecture and persistent development
IOSR Journal of Electronics and Communication Engineering(IOSR-JECE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of electronics and communication engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in electronics and communication engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
DYNAMIC OPTIMIZATION OF OVERLAP-AND-ADD LENGTH OVER MIMO MBOFDM SYSTEM BASED ...ijwmn
An important role performed by Zero Padding (ZP) in multi-band OFDM (MB-OFDM) System. This role
show for low-complexity in résistance against multipath interference by reducing inter-carrier interference
(ICI) and eliminating the inter-symbol interference (ISI) Also, zero-padded suffix can be used to eliminate
ripples in the power spectral density in order to conform to FCC requirements. At the receiver of MB-OFDM system needs to use of a technique called as overlap-and-add (OLA). Which maintain the circular convolution property and take the multipath energy of the channel.In this paper, we proposed a method of performing overlap-and-add length for zero padded suffixes. Then,we studied the effect of this method, dynamic optimization of overlap-and-add (OLA) equalization, on the performance of MIMO MBOFDM system on Bit Error Rate (BER) with AWGN channel and SalehValenzuela (S-V) Multipath channel Model.In the dynamic optimization OLA, the Length of ZP depends on length of channel impulse response (CIR).
These measures, based on SNR, insert the ZP according to the measurement.Dynamic optimization of length of ZP improves the Performance of MIMO MBOFDM system. In fact wedeveloped a technique to select the length of ZP as function of SNR and CIR estimate. In our simulation
this technique improve to 0.6 dB at BER=10-2 with a multipath channels CM4
Spectrally efficient multicarrier modulation system for visible light communi...IJECEIAES
Visible Light Communication (VLC) has become an accolade to its radio frequency counterpart. In VLC system, orthogonal frequency division multiplexing (OFDM) has drawn much attention, because of simple equalization, high spectral efficiency, high data rate and robustness to intersymbol interference (ISI). Besides, there are emerging applications that ought to be gotten with low latency and high reliability. To diminish power requirements with no transmission capacity extension, Trellis coded modulation (TCM) is utilized as a part of the framework in which the free distance of trellis diagram is equivalent to the minimum distance between the points of constellation focuses in partitioned subsets, which augments the coding gain up i.e. the performance parameter viably. TCM together with VLC-OFDM enhances the transmission execution in reasonable frameworks. In this paper, we propose OFDM which is based on TCM and is planned and exeuted for digitized OFDM frameworks by presenting delta sigma modulation (DSM) considering VLC channel. Simulation results show that the proposed TCM based VLC-OFDM offers incredible robustness against noises and nonlinear degradation.
An important role performed by Zero Padding (ZP) in multi-band OFDM (MB-OFDM) System.
This role show for low-complexity in résistance against multipath interference by reducing
inter-carrier interference (ICI) and eliminating the inter-symbol interference (ISI) Also, zeropadded
suffix can be used to eliminate ripples in the power spectral density in order to conform
to FCC requirements.
At the receiver of MB-OFDM system needs to use of a technique called as overlap-and-add
(OLA). Which maintain the circular convolution property and take the multipath energy of the
channel.
In this paper, we proposed a method of performing overlap-and-add length for zero padded
suffixes. Then, we studied the effect of this method, dynamic optimization of overlap-and-add
(OLA) equalization, on the performance of MBOFDM system on Bit Error Rate (BER) with
AWGN channel and Saleh-Valenzuela (S-V) Multipath channel Model.
In the dynamic optimization OLA, the Length of ZP depends on length of channel impulse
response (CIR). These measures, based on SNR, insert the ZP according to the measurement.
Dynamic optimization of length of ZP improves the Performance of MBOFDM system. In fact
we developed a technique to select the length of ZP as function of SNR and CIR
estimate(repetition). In our simulation this technique improve to 3 dB at BER=10-2 with a
multipath channels CM4.
Comparison of Various Waveform Contenders of 5G Wireless Communication Based ...ijtsrd
This paper presents an extensive and fair comparison among the most promising waveform contenders for the 5G air interface which includes- Filtered OFDM, Filter-bank multi carrier (FBMC), universal filtered multi-carrier (UFMC) has been compared with OFDM in terms of spectral efficiency and bit error rate using mat lab. The disadvantages of OFDM have been addressed and it has shown that (fofdm), (UFMC), (FBMC) could be a more effective solution. FBMC is a method for improving out of band (OOB) characteristics by filtering each subcarrier, it is also expected to improve the Inter-Carrier Interference (ICI) characteristics while UFMC is a method for improving OOB characteristics by filtering each block. Raksha Vishnoi | Saurabh Gaur | Ashish Verma"Comparison of Various Waveform Contenders of 5G Wireless Communication Based on OFDM" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-2 | Issue-4 , June 2018, URL: http://www.ijtsrd.com/papers/ijtsrd15637.pdf http://www.ijtsrd.com/engineering/electronics-and-communication-engineering/15637/comparison-of-various-waveform-contenders-of-5g-wireless-communication-based-on-ofdm/raksha-vishnoi
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Research Inventy : International Journal of Engineering and Scienceresearchinventy
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Design of 4x4 optical MIMO using spatial ModulationSachin Talakeri
Utilizing illuminating LED arrays for visible light communication (VLC) in an indoor environment, an optical multiple-input multiple-output (MIMO) system has intrigued great interest. In order to increase the potential VLC data rates, multiple-input multiple-output (MIMO) systems have been proposed. MIMO schemes show the spectral efficiency improvement using spatial modulation
HYPERSPECTRAL IMAGERY CLASSIFICATION USING TECHNOLOGIES OF COMPUTATIONAL INTE...IAEME Publication
Texture information is exploited for classification of HSI (Hyperspectral Imagery) at high spatial resolution. For this purpose, framework employs to LBP (Local Binary Pattern) to extract local image features such as edges, corners & spots. After the extraction of LBP feature two levels of fusions are applied along with Gabor feature & spectral feature, i.e. Feature level fusion & Decision level fusion. In Feature level fusion multiple features are concurred before pattern classification. While in decision level fusion, it works on probability output of each individual classification pipeline combines the distinct decisions into final one. Decision level fusion consists of either hard fusion, soft fusion method. In hard fusion we consider majority part & in soft fusion linear logarithmic opinion pool at probability level (LOGP). In addition to this, extreme learning machine (ELM) classifier is included which is more efficient than support vector machine (SVM), used to provide probability classification output. It has simple structure with one hidden layer & one linear output layer. ELM trained much faster than SVM.
Performance comparison of coded and uncoded ieee 802.16 d systems under stanf...IJCNCJournal
Worldwide Interoperability for Microwave Access (WiMax), standardized asIEEE 802.16d is a popular
technology for broadband wireless communication system. Orthogonal Frequency Division Multiplexing
(OFDM) is the core of this technology.OFDMreduces Inter-symbol Interference (ISI) and hence improves
system performance (i.e., Bit Error Rate (BER)). To improve system performance further error correction
coding schemes have been included in WiMax. It is widely accepted thata coded system outperforms an
uncodedsystem. But, the performance improvement of a coded system depends on the channel conditions. In
this paper, we investigated and compared the performances of a coded and an uncoded WiMaxsystem
under a practical channel model called Stanford University Interim (SUI). Different modulation schemes
namely BPSK, QPSK, 16-QAM, and 64-QAM have been considered in this work. It is shown that the
selection of codedoruncoded WiMaxsystem should depend on the channel condition as well as on the
modulation used. It is also shown that anuncoded system outperforms a coded system under some channel
conditions.
Framework for wireless network security using quantum cryptographyIJCNCJournal
Data that is transient over an unsecured wireless network is always susceptible to being intercepted by
anyone within the range of the wireless signal. Hence providing secure communication to keep the user’s
information and devices safe when connected wirelessly has become one of the major concerns. Quantum cryptography provides a solution towards absolute communication security over the network by encoding
information as polarized photons, which can be sent through the air. This paper explores on the aspect of
application of quantum cryptography in wireless networks.
In this paper we present a methodology for integrating quantum cryptography and security of IEEE 802.11 wireless networks in terms of distribution of the encryption keys.
A fuzzy logic controllerfora two link functional manipulatorIJCNCJournal
This paper presents a new approach for designing a Fuzzy Logic Controller "FLC"for a dynamically multivariable nonlinear coupling system. The conventional controller with constant gains for different operating points may not be sufficient to guarantee satisfactory performance for Robot manipulator. The Fuzzy Logic Controller utilizes the error and the change of error as fuzzy linguistic inputs to regulate the system performance. The proposed controller have been developed to simulate the dynamic behavior of A
Two-Link Functional Manipulator. The new controller uses only the available information of the input-output for controlling the position and velocity of the robot axes of the motion of the end effectors
Dcf learn and performance analysis of 802.11 b wireless networkIJCNCJournal
Though WLAN wireless network has been widely deployed as the main split-flow deployment of the
communication network, little study emphasizes its performance as WLAN protocols were only designed for
the public communicating conveniently with each other. Actually that too much wireless access points
assembling together will cause self-interference to the whole WLAN network. This paper investigates the
distributed coordination function (DCF) learn and the performance study of 802.11b networks. Firstly, our
study illustrates the performance of its MAC layer and its fairness issues related to DCF. Next we propose
the details which should be paid attention to in deploying network services. Then, performance analyses
are evaluated by simulation and real test for a dense wireless network. Our main goal is to give proposals
to network operators how to design a WLAN network more standardized and orderly.
LTE QOS DYNAMIC RESOURCE BLOCK ALLOCATION WITH POWER SOURCE LIMITATION AND QU...IJCNCJournal
3GPP has defined the long term evolution (LTE) for 3G radio access in order to maintain the future
competitiveness for 3G technology, the system provides the capability of supporting a mixture of services
with different quality of service (QoS) requirements. This paper proposes a new cross-layer scheduling
algorithm to satisfy better QoS parameters for real time applications. The proposed algorithm takes care of
allocating resource blocks (RBs) with different modulation and coding schemes (MCS) according to target
bit error rate (BER), user equipment supportable MCS, queue stability constraints and available transmit
power constraints. The proposed algorithm has been valued, compared with an earlier allocation algorithm
in terms of service rate and packet delay and showed better performance regards the real time
applications.
DYNAMIC OPTIMIZATION OF OVERLAP-AND-ADD LENGTH OVER MIMO MBOFDM SYSTEM BASED ...ijwmn
An important role performed by Zero Padding (ZP) in multi-band OFDM (MB-OFDM) System. This role
show for low-complexity in résistance against multipath interference by reducing inter-carrier interference
(ICI) and eliminating the inter-symbol interference (ISI) Also, zero-padded suffix can be used to eliminate
ripples in the power spectral density in order to conform to FCC requirements. At the receiver of MB-OFDM system needs to use of a technique called as overlap-and-add (OLA). Which maintain the circular convolution property and take the multipath energy of the channel.In this paper, we proposed a method of performing overlap-and-add length for zero padded suffixes. Then,we studied the effect of this method, dynamic optimization of overlap-and-add (OLA) equalization, on the performance of MIMO MBOFDM system on Bit Error Rate (BER) with AWGN channel and SalehValenzuela (S-V) Multipath channel Model.In the dynamic optimization OLA, the Length of ZP depends on length of channel impulse response (CIR).
These measures, based on SNR, insert the ZP according to the measurement.Dynamic optimization of length of ZP improves the Performance of MIMO MBOFDM system. In fact wedeveloped a technique to select the length of ZP as function of SNR and CIR estimate. In our simulation
this technique improve to 0.6 dB at BER=10-2 with a multipath channels CM4
Spectrally efficient multicarrier modulation system for visible light communi...IJECEIAES
Visible Light Communication (VLC) has become an accolade to its radio frequency counterpart. In VLC system, orthogonal frequency division multiplexing (OFDM) has drawn much attention, because of simple equalization, high spectral efficiency, high data rate and robustness to intersymbol interference (ISI). Besides, there are emerging applications that ought to be gotten with low latency and high reliability. To diminish power requirements with no transmission capacity extension, Trellis coded modulation (TCM) is utilized as a part of the framework in which the free distance of trellis diagram is equivalent to the minimum distance between the points of constellation focuses in partitioned subsets, which augments the coding gain up i.e. the performance parameter viably. TCM together with VLC-OFDM enhances the transmission execution in reasonable frameworks. In this paper, we propose OFDM which is based on TCM and is planned and exeuted for digitized OFDM frameworks by presenting delta sigma modulation (DSM) considering VLC channel. Simulation results show that the proposed TCM based VLC-OFDM offers incredible robustness against noises and nonlinear degradation.
An important role performed by Zero Padding (ZP) in multi-band OFDM (MB-OFDM) System.
This role show for low-complexity in résistance against multipath interference by reducing
inter-carrier interference (ICI) and eliminating the inter-symbol interference (ISI) Also, zeropadded
suffix can be used to eliminate ripples in the power spectral density in order to conform
to FCC requirements.
At the receiver of MB-OFDM system needs to use of a technique called as overlap-and-add
(OLA). Which maintain the circular convolution property and take the multipath energy of the
channel.
In this paper, we proposed a method of performing overlap-and-add length for zero padded
suffixes. Then, we studied the effect of this method, dynamic optimization of overlap-and-add
(OLA) equalization, on the performance of MBOFDM system on Bit Error Rate (BER) with
AWGN channel and Saleh-Valenzuela (S-V) Multipath channel Model.
In the dynamic optimization OLA, the Length of ZP depends on length of channel impulse
response (CIR). These measures, based on SNR, insert the ZP according to the measurement.
Dynamic optimization of length of ZP improves the Performance of MBOFDM system. In fact
we developed a technique to select the length of ZP as function of SNR and CIR
estimate(repetition). In our simulation this technique improve to 3 dB at BER=10-2 with a
multipath channels CM4.
Comparison of Various Waveform Contenders of 5G Wireless Communication Based ...ijtsrd
This paper presents an extensive and fair comparison among the most promising waveform contenders for the 5G air interface which includes- Filtered OFDM, Filter-bank multi carrier (FBMC), universal filtered multi-carrier (UFMC) has been compared with OFDM in terms of spectral efficiency and bit error rate using mat lab. The disadvantages of OFDM have been addressed and it has shown that (fofdm), (UFMC), (FBMC) could be a more effective solution. FBMC is a method for improving out of band (OOB) characteristics by filtering each subcarrier, it is also expected to improve the Inter-Carrier Interference (ICI) characteristics while UFMC is a method for improving OOB characteristics by filtering each block. Raksha Vishnoi | Saurabh Gaur | Ashish Verma"Comparison of Various Waveform Contenders of 5G Wireless Communication Based on OFDM" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-2 | Issue-4 , June 2018, URL: http://www.ijtsrd.com/papers/ijtsrd15637.pdf http://www.ijtsrd.com/engineering/electronics-and-communication-engineering/15637/comparison-of-various-waveform-contenders-of-5g-wireless-communication-based-on-ofdm/raksha-vishnoi
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Research Inventy : International Journal of Engineering and Scienceresearchinventy
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Design of 4x4 optical MIMO using spatial ModulationSachin Talakeri
Utilizing illuminating LED arrays for visible light communication (VLC) in an indoor environment, an optical multiple-input multiple-output (MIMO) system has intrigued great interest. In order to increase the potential VLC data rates, multiple-input multiple-output (MIMO) systems have been proposed. MIMO schemes show the spectral efficiency improvement using spatial modulation
HYPERSPECTRAL IMAGERY CLASSIFICATION USING TECHNOLOGIES OF COMPUTATIONAL INTE...IAEME Publication
Texture information is exploited for classification of HSI (Hyperspectral Imagery) at high spatial resolution. For this purpose, framework employs to LBP (Local Binary Pattern) to extract local image features such as edges, corners & spots. After the extraction of LBP feature two levels of fusions are applied along with Gabor feature & spectral feature, i.e. Feature level fusion & Decision level fusion. In Feature level fusion multiple features are concurred before pattern classification. While in decision level fusion, it works on probability output of each individual classification pipeline combines the distinct decisions into final one. Decision level fusion consists of either hard fusion, soft fusion method. In hard fusion we consider majority part & in soft fusion linear logarithmic opinion pool at probability level (LOGP). In addition to this, extreme learning machine (ELM) classifier is included which is more efficient than support vector machine (SVM), used to provide probability classification output. It has simple structure with one hidden layer & one linear output layer. ELM trained much faster than SVM.
Performance comparison of coded and uncoded ieee 802.16 d systems under stanf...IJCNCJournal
Worldwide Interoperability for Microwave Access (WiMax), standardized asIEEE 802.16d is a popular
technology for broadband wireless communication system. Orthogonal Frequency Division Multiplexing
(OFDM) is the core of this technology.OFDMreduces Inter-symbol Interference (ISI) and hence improves
system performance (i.e., Bit Error Rate (BER)). To improve system performance further error correction
coding schemes have been included in WiMax. It is widely accepted thata coded system outperforms an
uncodedsystem. But, the performance improvement of a coded system depends on the channel conditions. In
this paper, we investigated and compared the performances of a coded and an uncoded WiMaxsystem
under a practical channel model called Stanford University Interim (SUI). Different modulation schemes
namely BPSK, QPSK, 16-QAM, and 64-QAM have been considered in this work. It is shown that the
selection of codedoruncoded WiMaxsystem should depend on the channel condition as well as on the
modulation used. It is also shown that anuncoded system outperforms a coded system under some channel
conditions.
Framework for wireless network security using quantum cryptographyIJCNCJournal
Data that is transient over an unsecured wireless network is always susceptible to being intercepted by
anyone within the range of the wireless signal. Hence providing secure communication to keep the user’s
information and devices safe when connected wirelessly has become one of the major concerns. Quantum cryptography provides a solution towards absolute communication security over the network by encoding
information as polarized photons, which can be sent through the air. This paper explores on the aspect of
application of quantum cryptography in wireless networks.
In this paper we present a methodology for integrating quantum cryptography and security of IEEE 802.11 wireless networks in terms of distribution of the encryption keys.
A fuzzy logic controllerfora two link functional manipulatorIJCNCJournal
This paper presents a new approach for designing a Fuzzy Logic Controller "FLC"for a dynamically multivariable nonlinear coupling system. The conventional controller with constant gains for different operating points may not be sufficient to guarantee satisfactory performance for Robot manipulator. The Fuzzy Logic Controller utilizes the error and the change of error as fuzzy linguistic inputs to regulate the system performance. The proposed controller have been developed to simulate the dynamic behavior of A
Two-Link Functional Manipulator. The new controller uses only the available information of the input-output for controlling the position and velocity of the robot axes of the motion of the end effectors
Dcf learn and performance analysis of 802.11 b wireless networkIJCNCJournal
Though WLAN wireless network has been widely deployed as the main split-flow deployment of the
communication network, little study emphasizes its performance as WLAN protocols were only designed for
the public communicating conveniently with each other. Actually that too much wireless access points
assembling together will cause self-interference to the whole WLAN network. This paper investigates the
distributed coordination function (DCF) learn and the performance study of 802.11b networks. Firstly, our
study illustrates the performance of its MAC layer and its fairness issues related to DCF. Next we propose
the details which should be paid attention to in deploying network services. Then, performance analyses
are evaluated by simulation and real test for a dense wireless network. Our main goal is to give proposals
to network operators how to design a WLAN network more standardized and orderly.
LTE QOS DYNAMIC RESOURCE BLOCK ALLOCATION WITH POWER SOURCE LIMITATION AND QU...IJCNCJournal
3GPP has defined the long term evolution (LTE) for 3G radio access in order to maintain the future
competitiveness for 3G technology, the system provides the capability of supporting a mixture of services
with different quality of service (QoS) requirements. This paper proposes a new cross-layer scheduling
algorithm to satisfy better QoS parameters for real time applications. The proposed algorithm takes care of
allocating resource blocks (RBs) with different modulation and coding schemes (MCS) according to target
bit error rate (BER), user equipment supportable MCS, queue stability constraints and available transmit
power constraints. The proposed algorithm has been valued, compared with an earlier allocation algorithm
in terms of service rate and packet delay and showed better performance regards the real time
applications.
A novel scheme to improve the spectrum sensing performanceIJCNCJournal
Due to limited availability of spectrum for license
d users only, the need for secondary access by unli
censed
users is increasing. Cognitive radio turns out to b
e helping this situation because all that is needed
is a
technique that could efficiently detect the empty s
paces and provide them to the secondary devices wit
hout
causing any interference to the primary (licensed)
users. Spectrum sensing is the foremost function of
the
cognitive radio which senses the environment for wh
ite spaces. Energy detection is one of the various
spectrum sensing techniques that are under research
. Earlier it was shown that energy detection works
better under AWGN channel as compared to Rayleigh c
hannel, however the conventional spectrum sensing
techniques have a high probability of false alarm a
nd also show a better probability of detection for
higher
values of SNR. There is a need for a new technique
that shows a reduced probability of false alarm as
well
as an increase in the probability of detection for
lower values of SNR. In the present work the conven
tional
energy detection technique has been enhanced to get
better results.
Different date block size using to evaluate the performance between different...IJCNCJournal
The different computer networks whether wired or wireless are becoming more popular with its high
security aspect. Different security algorithms and technique are using to avoid any aforementioned attacks.
One of these technique is a cryptography technique that makes the data as unreadable during the transfer
hence; there is no chance to reclaim the information. Presently, most of the users are using various media
types and internet to transfer the data but, it has the chance to retrieve the data by using these media types.
The perfect solution for this problem is to provide security on time-to-time basis; this stage is always
significant to the security related community discussions. This paper explains the comparison between the
run time of three different encryption algorithms which are DES, AES and Blowfish The compression
includes using different modes, data block size and different operation modes. As a result, Blowfish
algorithm followed by AES take less time for running compared to DES.
Key management in information centric networkingIJCNCJournal
Information centric networking (ICN) has been in the spotlight of recent research. It is an emerging
communication paradigm that relays on the concept of publish and subscribe. It aims to revise the current
Internet with a new clean slate architecture where the design is completely different from today’s location
based model. To secure the forwarding plan in this network, it is vital to have a time based transient
forwarding identifiers by periodically changing the network link identifiers. This assumes shared keys to be
distributed prior the communications between an entity termed topology manager (TM) and each forwarder
in the network. Exchanging and sharing a secret key between two parties is one of most critical functions in
cryptography that needs to be more concerned when integrating cryptographic functions into the system. As
ICN is brand new Internet architecture, many existing cryptography protocols may need to be redesigned
to fit this new architecture. Therefore, this paper focuses on the security aspect of ICN and proposes an
initial design to deploy the integrated Diffie-Hellman-DSA key exchange protocol as a key distributions
mechanism.
A review study of handover performance in mobile ipIJCNCJournal
The Mobile Internet Protocol (Mobile IP) is an extension to the Internet Protocol proposed by the Internet
Engineering Task Force (IETF) that addresses the mobility issues. In order to support un-interrupted
services and seamless mobility of nodes across the networks (and/or sub-networks) with permanent IP
addresses, handover is performed in mobile IP enabled networks. Handover in mobile IP is source cause of
performance degradation as it results in increased latency and packet loss during handover. Other issues
like scalability issues, ordered packet delivery issues, control plane management issues etc are also
adversely affected by it. The paper provides a constructive survey by classifying, discussing and comparing
different handover techniques that have been proposed so far, for enhancing the performance during
handovers. Finally some general solutions that have been used to solve handover related problems are
briefly discussed.
PAPR REDUCTION OF OFDM SIGNAL BY USING COMBINED HADAMARD AND MODIFIED MEU-LAW...IJCNCJournal
Orthogonal frequency division multiplexing (OFDM) is a technique which gives high quality of service (QOS) to the users by mitigating the fading signals as well as high data rates in multimedia services. However, the peak-to-average power ratio (PAPR) is a technical challenge that reduces the efficiency of RF power amplifiers. In this paper, we propose the combined Hadamard transform and modified meu-law companding transform method in order to lessen the effects of the peak-to-average power ratio of the
OFDM signal. Simulation results show that the proposed scheme reduces PAPR compared to other companding techniques as well as the Hadamard transform technique when used on its own.
Further results on the joint time delay and frequency estimation without eige...IJCNCJournal
Joint Time Delay and Frequency Estimation (JTDFE) problem of complex sinusoidal signals received at
two separated sensors is an attractive problem that has been considered for several engineering
applications. In this paper, a high resolution null (noise) subspace method without eigenvalue
decomposition is proposed. The direct data Matrix is replaced by an upper triangular matrix obtained from
Rank-Revealing LU (RRLU) factorization. The RRLU provides accurate information about the rank and the
numerical null space which make it a valuable tool in numerical linear algebra.The proposed novel method
decreases the computational complexity of JTDFE approximately to the half compared with RRQR
methods. The proposed method generates estimates of the unknown parameters which are based on the
observation and/or covariance matrices. This leads to a significant improvement in the computational load.
Computer simulations are included in this paper to demonstrate the proposed method.
On the development of methodology for planning and cost modeling of a wide ar...IJCNCJournal
The most important stages in designing a
computer
network
in a
wider geographical area include:
definition of requirements, topological description
,
identification and calculation of relevant parameters
(
i
.
e
.
traffic matrix
)
, determining the shortest path between nodes, quantification of the effect of various
levels
of technical and technological development of urban areas involved, the cost of technology
,
and the
cost of services. The
se
parameters differ for WAN networks in different regions
–
their calculation depends
directly
on
the data “
i
n the field
”
: number of inhabitants, distance between populated areas,
network
traffic
density
,
as well as
available
bandwidth
. The
main
reason for identification and evaluation of these
parameters
is
to develop a model that could
meet the
constraints
im
posed by poten
tial beneficiaries.
In this
paper
,
we develop a methodology for planning and cost
-
modeling of a wide area network
and
validate it
in
a case study,
under the
supposition
that
behavioral interactions of individuals and groups play a significant
role and have
to be taken into consideration
by employing either simple or composite indicators of
socioeconomic status
.
ETOR-Efficient Token based Opportunistic RoutingIJCNCJournal
This paper proposes an Efficient Token based Opportunistic Routing called ETOR, which is an
improvement to the token based coordination approach for opportunistic routing proposed by Economy[1].
In Economy, method used for finding the connected candidate order chooses neighbor as the next
candidate by considering ETX of that neighbor towards the source but it does not consider the link
probability between the relay candidate and neighbor to be selected. ETOR proposes variant methods for
finding the connected candidate order in token based opportunistic routing by considering both the ETX
of the neighbor towards source as well as ETX of the relay towards sending candidate which avoids weaker
links between its intermediate nodes thereby improving the throughput and reducing the AA Ratio. We also
propose a solution for reducing the number of hops traversed by the token, which in turn increases the
token generation speed. Simulation results show that the proposed ETOR approaches perform better than
Economy approach in terms of AA Ratio, number of hops traversed by the token and number of token
traversals.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
A simulation study of wi max based communication system using deliberately cl...eSAT Journals
Abstract WiMAX is a highly sophisticated technology in the broadband wireless access communication system. Scalable Orthogonal Frequency Division Multiple Access (OFDMA) is a key technology behind mobile WiMAX and it is also expected to play a key role in 3GPP Long Term Evolution (LTE) standards. Designers and OEMs have to concentrate on flexibility, scalability and stability of the overall Orthogonal Frequency Division Multiplexing (OFDM) system along with its proper data processing and channeling process to achieve high performance and competitiveness. In this paper, the performance of a strictly band limited OFDM signal is examined using deliberate clipping method, one of the simplest signal distortion based way to reduce high Peak to Average Power Ratio (PAPR) and its effect on the resultant Bit Error Rate (BER) against Signal to Noise Ratio (SNR) performance. A simulation program using MATLAB software was developed to investigate performance of OFDM signal by optimization of different parameters such values of FFT size, Cyclic Prefix co-efficient (CPC) and The Voltage Clipping Ratio (VCR). The simulation results show that with the increment of VCR at optimized parameter values of FFT size and CP, the performance of BER vs SNR improves compared to the results found without clipping. Keywords: WiMAX, PAPR, OFDM, CPC, Voltage Clipping Ratio, Deliberately Clipped
A simulation study of wi max based communication system using deliberately cl...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
ESTIMATION AND COMPENSATION OF INTER CARRIER INTERFERENCE IN WIMAX PHYSICAL L...ijngnjournal
WiMAX is Wireless Interoperability for Microwave Access has emerged as a promising solution for transmission of higher data rates for fixed and mobile applications. IEEE 802.16d and e are the standards proposed by WiMAX group for fixed and mobile. As the wireless channel have so many limitation Such as Multipath, Doppler spread, Delay spread and Line Of Sight (LOS)/Non Line Of Sight (NLOS) components. To attain higher data rates the Multi Carrier System with Multiple Input and Multiple Output (MIMO) is incorporated in the WiMAX. The Orthogonal Frequency Division Multiplexing (OFDM) is a multi carrier technique used with the WiMAX systems. In OFDM the available spectrum is split into numerous narrow band channels of dissimilar frequencies to achieve high data rate in a multi path fading environment. And all these sub carriers are considered to be orthogonal to each other. As the number of sub carriers is increased there is no guarantee of sustained orthogonality, i.e. at some point the carriers are not
independent to each other, and hence where the orthogonality can be loosed which leads to interference and also owing to the synchronization between transmitter and receiver local oscillator, it causes interference known as Inter Carrier Interference (ICI). The systems uses MIMO-OFDM will suffer with the effects of ICI and Carrier Frequency Offset (CFO) “ε”. However these affect the power leakage in the midst of sub carriers, consequently degrading the system performance. In this paper a new approach is proposed in order to reduce the ICI caused in WiMAX and improve the system performance. In this scheme at the transmitter side the modulated data and a few predefined pilot symbols are mapped onto the non
neighboring sub carriers with weighting coefficients of +1 and -1. With the aid of pilot symbols the frequency offset is exactly estimated by using Maximum Likelihood Estimation (MLE) and hence can be minimized. At demodulation stage the received signals are linearly combined along with their weighted
coefficients and pilot symbols, called as Pilot Aided Self Cancellation Method (PASCS). And also to realize the various wireless environments the simulations are carried out on Stanford University Interim (SUI) channels. The simulation results shows that by incorporating this method into WiMAX systems it performs better when the Line Of Sight (LOS) component is present in the transmission and also it improves the Bit Error Rate (BER) and Carrier to Interference Ratio (CIR). The CIR can be improved 20 dB. In this paper the effectiveness of PASCS scheme is compared with the Self Cancellation Method (SCM). It provides accurate estimation of frequency offset and when residual CFO is less significant the ICI can be diminished successfully.
EFFECTS OF FILTERS ON THE PERFORMANCE OF DVB-T RECEIVERijwmn
Digital Video Broadcasting-Terrestrial (DVB-T) is an international standard for digital television
services. Orthogonal Frequency Division Multiplexing (OFDM) is the core of this technology. OFDM
based system like DVB-T can handle multipath fading and hence it can minimize Inter Symbol
Interference (ISI). DVB-T has some limitations too namely large dynamic range of the signals and
sensitivity to frequency error. In order to overcome these limitations DVB-T receivers should be optimally
designed. In this paper we address the issues related to optimal DVB-T receiver design. There of several
signal processing units in a DVB-T receiver. A low-pass filter is one of them. In this paper, we consider
some classic filters namely Butterworth, Chebyshev, and elliptic in the DVB-T receiver. The effects of
different filters on the performances of DVB-T receiver have been investigated and compared in this
paper under AWGN channel condition
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Performance enhancement of maximum ratio transmission in 5G system with multi...IJECEIAES
The downlink multi-user precoding of the multiple-input multiple-output (MIMO) method includes optimal channel state information at the base station and a variety of linear precoding (LP) schemes. Maximum ratio transmission (MRT) is among the common precoding schemes but does not provide good performance with massive MIMO, such as high bit error rate (BER) and low throughput. The orthogonal frequency division multiplexing (OFDM) and precoding schemes used in 5G have a flaw in high-speed environments. Given that the Doppler effect induces frequency changes, orthogonality between OFDM subcarriers is disrupted and their throughput output is decreased and BER is decreased. This study focuses on solving this problem by improving the performance of a 5G system with MRT, specifically by using a new design that includes weighted overlap and add (WOLA) with MRT. The current research also compares the standard system MRT with OFDM with the proposed design (WOLA-MRT) to find the best performance on throughput and BER. Improved system results show outstanding performance enhancement over a standard system, and numerous improvements with massive MIMO, such as best BER and throughput. Its approximately 60% more throughput than the traditional systems. Lastly, the proposed system improves BER by approximately 2% compared with the traditional system.
Simulation of IEEE 802.16e Physical LayerIOSR Journals
Abstract : Growth in technology has led to unprecedented demand for high speed Internet access. IEEE
802.16e (Mobile WiMAX) is a wireless communication standard with high data transfer rates and good
performance. It not only is efficient as compared to its counterpart technologies today (Wi-Fi and 3G), but also
lays the foundation for 4G mobile communication. In 4G wireless communication systems, bandwidth is a
precious resource, and service providers are continuously met with the challenge of accommodating more users
within a limited allocated bandwidth. To increase data rate of wireless medium with higher performance,
Mobile WiMAX uses Orthogonal Frequency Division Multiple Access (OFDMA). This paper describes the
simulation of the physical layer of IEEE 802.16e using Simulink in Matlab 7.0 (R2010a). The system
performance is evaluated considering the Signal to noise ratio (SNR) and Bit error rate (BER) parameters.
Keywords: 802.16e, OFDMA, Mobile WiMAX.
One of vital parts of the mobile wireless channel is channel estimation significantly
improve the performance of the system, especially for 4G LTE and 5G systems. The
main goal of this project is to test the time-variant channel estimation using F-OFDM
model. It investigates the Mean Square Error (MSE), the Least Squares (LS) method
and compares performance of OFDM and F-OFDM using BER vs SNR.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Channel Estimation Techniques in MIMO-OFDM LTE SystemsCauses and Effects of C...IJERA Editor
There is an increasing demand for high data transmission rates with the evolution of the very large scale integration (VLSI) technology. The multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) systems are used to fulfill these requirements because of their unique properties such as high spectral efficiency, high data rate and resistance towards multipath propagation. MIMO-OFDM systems are finding their applications in the modern wireless communication systems like IEEE 802.11n, 4G and LTE. They also offer reliable communication with the increased coverage area. The bottleneck to the MIMO-OFDM systems is the estimation of the channel state information (CSI). This can be estimated with the help of any one of the Training Based, Semiblind and Blind Channel estimation algorithms. This paper presents various channel estimation algorithms, optimization techniques and their effective utilization in MIMO-OFDM for modern wireless LTE systems.
Integrated DWDM and MIMO-OFDM System for 4G High Capacity Mobile Communicatio...CSCJournals
Dense wavelength-division multiplexing (DWDM) technique is a very promising data transmission technology for utilizing the capacity of the fiber. By DWDM, multiple signals (video, audio, data etc) staggered in wavelength domain can be multiplexed and transmitted down the same fiber. The Multiple-input multiple-output (MIMO) wireless technology in combination with orthogonal frequency division multiplexing (MIMO-OFDM) is an attractive air-interface solution for next-generation wireless local area networks (WLANs) and fourth-generation mobile cellular wireless systems. This article provides an overview of the integrated DWDM MIMO-OFDM technology and focuses on DWDM transmitter design with adequate dispersion compensation for high data rate of 10Gbps ,MIMO-OFDM system design, space-time coded signaling, receiver design and performance analysis in terms of bit error rate for Integrated system. The simulation is carried out using powerful software tools Optisystem and MATLAB . In this paper a 64 channel DWDM system is simulated for transmission of baseband NRZ signal over fiber. Each of the transmission is at bit rate of 10 Gbps leading to high data rate transmission of 640 Gbps.The resultant Bit Error Rate(BER) is in the range 10-12 for DWDM system which is given as input to MIMO-OFDM system..This system performance is analyzed in terms of BER with SNR for Rayleigh, and AWGN channels and BER of 10-4 is achieved at SNR of 10dbs
Vehicle Ad Hoc Networks (VANETs) have become a viable technology to improve traffic flow and safety on the roads. Due to its effectiveness and scalability, the Wingsuit Search-based Optimised Link State Routing Protocol (WS-OLSR) is frequently used for data distribution in VANETs. However, the selection of MultiPoint Relays (MPRs) plays a pivotal role in WS-OLSR's performance. This paper presents an improved MPR selection algorithm tailored to WS-OLSR, designed to enhance the overall routing efficiency and reduce overhead. The analysis found that the current OLSR protocol has problems such as redundancy of HELLO and TC message packets or failure to update routing information in time, so a WS-OLSR routing protocol based on improved-MPR selection algorithm was proposed. Firstly, factors such as node mobility and link changes are comprehensively considered to reflect network topology changes, and the broadcast cycle of node HELLO messages is controlled through topology changes. Secondly, a new MPR selection algorithm is proposed, considering link stability issues and nodes. Finally, evaluate its effectiveness in terms of packet delivery ratio, end-to-end delay, and control message overhead. Simulation results demonstrate the superior performance of our improved MR selection algorithm when compared to traditional approaches.
A Novel Medium Access Control Strategy for Heterogeneous Traffic in Wireless ...IJCNCJournal
So far, Wireless Body Area Networks (WBANs) have played a pivotal role in driving the development of intelligent healthcare systems with broad applicability across various domains. Each WBAN consists of one or more types of sensors that can be embedded in clothing, attached directly to the body, or even implanted beneath an individual's skin. These sensors typically serve asingle application. However, the traffic generated by each sensor may have distinct requirements. This diversity necessitates a dual approach: tailored treatment based on the specific needs of each traffic typeand the fulfillment of application requirements, such asreliability and timeliness. Never the less, the presence of energy constraints and the unreliable nature of wireless communications make QoS provisioning under such networks a non-trivial task. In this context, the current paper introduces a novel Medium AccessControl (MAC) strategy for the regular traffic applications of WBANs, designed to significantly enhance efficiency when compared to the established MAC protocols IEEE 802.15.4 and IEEE 802.15.6, with a particular focus on improving reliability, timeliness, and energy efficiency.
May_2024 Top 10 Read Articles in Computer Networks & Communications.pdfIJCNCJournal
The International Journal of Computer Networks & Communications (IJCNC) is a bi monthly open access peer-reviewed journal that publishes articles which contribute new results in all areas of Computer Networks & Communications. The journal focuses on all technical and practical aspects of Computer Networks & data Communications. The goal of this journal is to bring together researchers and practitioners from academia and industry to focus on advanced networking concepts and establishing new collaborations in these areas.
A Topology Control Algorithm Taking into Account Energy and Quality of Transm...IJCNCJournal
The efficient use of energy in wireless sensor networks is critical for extending node lifetime. The network topology is one of the factors that have a significant impact on the energy usage at the nodes and the quality of transmission (QoT) in the network. We propose a topology control algorithm for software-defined wireless sensor networks (SDWSNs) in this paper. Our method is to formulate topology control algorithm as a nonlinear programming (NP) problem with the objective to optimizing two metrics, maximum communication range, and desired degree. This NP problem is solved at the SDWSN controller by employing the genetic algorithm (GA) to determine the best topology. The simulation results show that the proposed algorithm outperforms the MaxPower algorithm in terms of average node degree and energy expansion ratio.
Multi-Server user Authentication Scheme for Privacy Preservation with Fuzzy C...IJCNCJournal
The integration of artificial intelligence technology with a scalable Internet of Things (IoT) platform facilitates diverse smart communication services, allowing remote users to access services from anywhere at any time. The multi-server environment within IoT introduces a flexible security service model, enabling users to interact with any server through a single registration. To ensure secure and privacy preservation services for resources, an authentication scheme is essential. Zhao et al. recently introduced a user authentication scheme for the multi-server environment, utilizing passwords and smart cards, claiming resilience against well-known attacks. This paper conducts cryptanalysis on Zhao et al.'s scheme, focusing on denial of service and privacy attacks, revealing a lack of user-friendliness. Subsequently, we propose a new multi-server user authentication scheme for privacy preservation with fuzzy commitment over the IoT environment, addressing the shortcomings of Zhao et al.'s scheme. Formal security verification of the proposed scheme is conducted using the ProVerif simulation tool. Through both formal and informal security analyses, we demonstrate that the proposed scheme is resilient against various known attacks and those identified in Zhao et al.'s scheme.
Advanced Privacy Scheme to Improve Road Safety in Smart Transportation SystemsIJCNCJournal
In -Vehicle Ad-Hoc Network (VANET), vehicles continuously transmit and receive spatiotemporal data with neighboring vehicles, thereby establishing a comprehensive 360-degree traffic awareness system. Vehicular Network safety applications facilitate the transmission of messages between vehicles that are near each other, at regular intervals, enhancing drivers' contextual understanding of the driving environment and significantly improving traffic safety. Privacy schemes in VANETs are vital to safeguard vehicles’ identities and their associated owners or drivers. Privacy schemes prevent unauthorized parties from linking the vehicle's communications to a specific real-world identity by employing techniques such as pseudonyms, randomization, or cryptographic protocols. Nevertheless, these communications frequently contain important vehicle information that malevolent groups could use to Monitor the vehicle over a long period. The acquisition of this shared data has the potential to facilitate the reconstruction of vehicle trajectories, thereby posing a potential risk to the privacy of the driver. Addressing the critical challenge of developing effective and scalable privacy-preserving protocols for communication in vehicle networks is of the highest priority. These protocols aim to reduce the transmission of confidential data while ensuring the required level of communication. This paper aims to propose an Advanced Privacy Vehicle Scheme (APV) that periodically changes pseudonyms to protect vehicle identities and improve privacy. The APV scheme utilizes a concept called the silent period, which involves changing the pseudonym of a vehicle periodically based on the tracking of neighboring vehicles. The pseudonym is a temporary identifier that vehicles use to communicate with each other in a VANET. By changing the pseudonym regularly, the APV scheme makes it difficult for unauthorized entities to link a vehicle's communications to its real-world identity. The proposed APV is compared to the SLOW, RSP, CAPS, and CPN techniques. The data indicates that the efficiency of APV is a better improvement in privacy metrics. It is evident that the AVP offers enhanced safety for vehicles during transportation in the smart city.
April 2024 - Top 10 Read Articles in Computer Networks & CommunicationsIJCNCJournal
The International Journal of Computer Networks & Communications (IJCNC) is a bi monthly open access peer-reviewed journal that publishes articles which contribute new results in all areas of Computer Networks & Communications. The journal focuses on all technical and practical aspects of Computer Networks & data Communications. The goal of this journal is to bring together researchers and practitioners from academia and industry to focus on advanced networking concepts and establishing new collaborations in these areas.
DEF: Deep Ensemble Neural Network Classifier for Android Malware DetectionIJCNCJournal
Malware is one of the threats to security of computer networks and information systems. Since malware instances are available sufficiently, there is increased interest among researchers on usage of Artificial Intelligence (AI). Of late AI-enabled methods such as machine learning (ML) and deep learning paved way for solving many real-world problems. As it is a learning-based approach, accumulated training samples help in improving thequality of training and thus leveraging malware detection accuracy. Existing deep learning methods are focusing on learning-based malware detection systems. However, there is need for improving the state of the art through ensemble approach. Towards this end, in this paper we proposed a framework known as Deep Ensemble Framework (DEF) for automatic malware detection. The framework obtains features from training samples. From given malware instance a grayscale image is generated. There is another process to extract the opcode sequences. Convolutional Neural Network (CNN) and Long Short Term Memory (LSTM) techniques are used to obtain grayscale image and opcode sequence respectively. Afterwards, a stacking ensemble is employed in order to achieve efficient malware detection and classification. Malware samples collected fromthe Internet sources and Microsoft are used for theempirical study. An algorithm known as Ensemble Learning for Automatic Malware Detection (EL-AML) is proposed to realize our framework. Another algorithm named Pre-Process is proposed to assist the EL-AML algorithm for obtaining intermediate features required by CNN and LSTM.Empirical study reveals that our framework outperforms many existing methods in terms of speed-up and accuracy.
High Performance NMF Based Intrusion Detection System for Big Data IOT TrafficIJCNCJournal
With the emergence of smart devices and the Internet of Things (IoT), millions of users connected to the network produce massive network traffic datasets. These vast datasets of network traffic, Big Data are challenging to store, deal with and analyse using a single computer. In this paper we developed parallel implementation using a High Performance Computer (HPC) for the Non-Negative Matrix Factorization technique as an engine for an Intrusion Detection System (HPC-NMF-IDS). The large IoT traffic datasets of order of millions samples are distributed evenly on all the computing cores for both storage and speedup purpose. The distribution of computing tasks involved in the Matrix Factorization takes into account the reduction of the communication cost between the computing cores. The experiments we conducted on the proposed HPC-IDS-NMF give better results than the traditional ML-based intrusion detection systems. We could train the HPC model with datasets of one million samples in only 31 seconds instead of the 40 minutes using one processor), that is a speed up of 87 times. Moreover, we have got an excellent detection accuracy rate of 98% for KDD dataset.
A Novel Medium Access Control Strategy for Heterogeneous Traffic in Wireless ...IJCNCJournal
So far, Wireless Body Area Networks (WBANs) have played a pivotal role in driving the development of intelligent healthcare systems with broad applicability across various domains. Each WBAN consists of one or more types of sensors that can be embedded in clothing, attached directly to the body, or even implanted beneath an individual's skin. These sensors typically serve asingle application. However, the traffic generated by each sensor may have distinct requirements. This diversity necessitates a dual approach: tailored treatment based on the specific needs of each traffic typeand the fulfillment of application requirements, such asreliability and timeliness. Never the less, the presence of energy constraints and the unreliable nature of wireless communications make QoS provisioning under such networks a non-trivial task. In this context, the current paper introduces a novel Medium AccessControl (MAC) strategy for the regular traffic applications of WBANs, designed to significantly enhance efficiency when compared to the established MAC protocols IEEE 802.15.4 and IEEE 802.15.6, with a particular focus on improving reliability, timeliness, and energy efficiency.
A Topology Control Algorithm Taking into Account Energy and Quality of Transm...IJCNCJournal
The efficient use of energy in wireless sensor networks is critical for extending node lifetime. The network topology is one of the factors that have a significant impact on the energy usage at the nodes and the quality of transmission (QoT) in the network. We propose a topology control algorithm for software-defined wireless sensor networks (SDWSNs) in this paper. Our method is to formulate topology control algorithm as a nonlinear programming (NP) problem with the objective to optimizing two metrics, maximum communication range, and desired degree. This NP problem is solved at the SDWSN controller by employing the genetic algorithm (GA) to determine the best topology. The simulation results show that the proposed algorithm outperforms the MaxPower algorithm in terms of average node degree and energy expansion ratio.
Multi-Server user Authentication Scheme for Privacy Preservation with Fuzzy C...IJCNCJournal
The integration of artificial intelligence technology with a scalable Internet of Things (IoT) platform facilitates diverse smart communication services, allowing remote users to access services from anywhere at any time. The multi-server environment within IoT introduces a flexible security service model, enabling users to interact with any server through a single registration. To ensure secure and privacy preservation services for resources, an authentication scheme is essential. Zhao et al. recently introduced a user authentication scheme for the multi-server environment, utilizing passwords and smart cards, claiming resilience against well-known attacks. This paper conducts cryptanalysis on Zhao et al.'s scheme, focusing on denial of service and privacy attacks, revealing a lack of user-friendliness. Subsequently, we propose a new multi-server user authentication scheme for privacy preservation with fuzzy commitment over the IoT environment, addressing the shortcomings of Zhao et al.'s scheme. Formal security verification of the proposed scheme is conducted using the ProVerif simulation tool. Through both formal and informal security analyses, we demonstrate that the proposed scheme is resilient against various known attacks and those identified in Zhao et al.'s scheme.
Advanced Privacy Scheme to Improve Road Safety in Smart Transportation SystemsIJCNCJournal
In -Vehicle Ad-Hoc Network (VANET), vehicles continuously transmit and receive spatiotemporal data with neighboring vehicles, thereby establishing a comprehensive 360-degree traffic awareness system. Vehicular Network safety applications facilitate the transmission of messages between vehicles that are near each other, at regular intervals, enhancing drivers' contextual understanding of the driving environment and significantly improving traffic safety. Privacy schemes in VANETs are vital to safeguard vehicles’ identities and their associated owners or drivers. Privacy schemes prevent unauthorized parties from linking the vehicle's communications to a specific real-world identity by employing techniques such as pseudonyms, randomization, or cryptographic protocols. Nevertheless, these communications frequently contain important vehicle information that malevolent groups could use to Monitor the vehicle over a long period. The acquisition of this shared data has the potential to facilitate the reconstruction of vehicle trajectories, thereby posing a potential risk to the privacy of the driver. Addressing the critical challenge of developing effective and scalable privacy-preserving protocols for communication in vehicle networks is of the highest priority. These protocols aim to reduce the transmission of confidential data while ensuring the required level of communication. This paper aims to propose an Advanced Privacy Vehicle Scheme (APV) that periodically changes pseudonyms to protect vehicle identities and improve privacy. The APV scheme utilizes a concept called the silent period, which involves changing the pseudonym of a vehicle periodically based on the tracking of neighboring vehicles. The pseudonym is a temporary identifier that vehicles use to communicate with each other in a VANET. By changing the pseudonym regularly, the APV scheme makes it difficult for unauthorized entities to link a vehicle's communications to its real-world identity. The proposed APV is compared to the SLOW, RSP, CAPS, and CPN techniques. The data indicates that the efficiency of APV is a better improvement in privacy metrics. It is evident that the AVP offers enhanced safety for vehicles during transportation in the smart city.
DEF: Deep Ensemble Neural Network Classifier for Android Malware DetectionIJCNCJournal
Malware is one of the threats to security of computer networks and information systems. Since malware instances are available sufficiently, there is increased interest among researchers on usage of Artificial Intelligence (AI). Of late AI-enabled methods such as machine learning (ML) and deep learning paved way for solving many real-world problems. As it is a learning-based approach, accumulated training samples help in improving thequality of training and thus leveraging malware detection accuracy. Existing deep learning methods are focusing on learning-based malware detection systems. However, there is need for improving the state of the art through ensemble approach. Towards this end, in this paper we proposed a framework known as Deep Ensemble Framework (DEF) for automatic malware detection. The framework obtains features from training samples. From given malware instance a grayscale image is generated. There is another process to extract the opcode sequences. Convolutional Neural Network (CNN) and Long Short Term Memory (LSTM) techniques are used to obtain grayscale image and opcode sequence respectively. Afterwards, a stacking ensemble is employed in order to achieve efficient malware detection and classification. Malware samples collected fromthe Internet sources and Microsoft are used for theempirical study. An algorithm known as Ensemble Learning for Automatic Malware Detection (EL-AML) is proposed to realize our framework. Another algorithm named Pre-Process is proposed to assist the EL-AML algorithm for obtaining intermediate features required by CNN and LSTM.Empirical study reveals that our framework outperforms many existing methods in terms of speed-up and accuracy.
High Performance NMF based Intrusion Detection System for Big Data IoT TrafficIJCNCJournal
With the emergence of smart devices and the Internet of Things (IoT), millions of users connected to the network produce massive network traffic datasets. These vast datasets of network traffic, Big Data are challenging to store, deal with and analyse using a single computer. In this paper we developed parallel implementation using a High Performance Computer (HPC) for the Non-Negative Matrix Factorization technique as an engine for an Intrusion Detection System (HPC-NMF-IDS). The large IoT traffic datasets of order of millions samples are distributed evenly on all the computing cores for both storage and speedup purpose. The distribution of computing tasks involved in the Matrix Factorization takes into account the reduction of the communication cost between the computing cores. The experiments we conducted on the proposed HPC-IDS-NMF give better results than the traditional ML-based intrusion detection systems. We could train the HPC model with datasets of one million samples in only 31 seconds instead of the 40 minutes using one processor), that is a speed up of 87 times. Moreover, we have got an excellent detection accuracy rate of 98% for KDD dataset.
IoT Guardian: A Novel Feature Discovery and Cooperative Game Theory Empowered...IJCNCJournal
Cyber intrusion attacks increasingly target the Internet of Things (IoT) ecosystem, exploiting vulnerable devices and networks. Malicious activities must be identified early to minimize damage and mitigate threats. Using actual benign and attack traffic from the CICIoT2023 dataset, this WORK aims to evaluate and benchmark machine-learning techniques for IoT intrusion detection. There are four main phases to the system. First, the CICIoT2023 dataset is refined to remove irrelevant features and clean up missing and duplicate data. The second phase employs statistical models and artificial intelligence to discover novel features. The most significant features are then selected in the third phase based on cooperative game theory. Using the original CICIoT2023 dataset and a dataset containing only novel features, we train and evaluate a variety of machine learning classifiers. On the original dataset, Random Forest achieved the highest accuracy of 99%. Still, with novel features, Random Forest's performance dropped only slightly (96%) while other models achieved significantly lower accuracy. As a whole, the work contributes substantial contributions to tailored feature engineering, feature selection, and rigorous benchmarking of IoT intrusion detection techniques. IoT networks and devices face continuously evolving threats, making it necessary to develop robust intrusion detection systems.
Enhancing Traffic Routing Inside a Network through IoT Technology & Network C...IJCNCJournal
IoT networking uses real items as stationary or mobile nodes. Mobile nodes complicate networking. Internet of Things (IoT) networks have a lot of control overhead messages because devices are mobile. These signals are generated by the constant flow of control data as such device identity, geographical positioning, node mobility, device configuration, and others. Network clustering is a popular overhead communication management method. Many cluster-based routing methods have been developed to address system restrictions. Node clustering based on the Internet of Things (IoT) protocol, may be used to cluster all network nodes according to predefined criteria. Each cluster will have a Smart Designated Node. SDN cluster management is efficient. Many intelligent nodes remain in the network. The network design spreads these signals. This paper presents an intelligent and responsive routing approach for clustered nodes in IoT networks. An existing method builds a new sub-area clustered topology. The Nodes Clustering Based on the Internet of Things (NCIoT) method improves message transmission between any two nodes. This will facilitate the secure and reliable interchange of healthcare data between professionals and patients. NCIoT is a system that organizes nodes in the Internet of Things (IoT) by grouping them together based on their proximity. It also picks SDN routes for these nodes. This approach involves selecting one option from a range of choices and preparing for likely outcomes problem addressing limitations on activities is a primary focus during the review process. Predictive inquiry employs the process of analyzing data to forecast and anticipate future events. This document provides an explanation of compact units. The Predictive Inquiry Small Packets (PISP) improved its backup system and partnered with SDN to establish a routing information table for each intelligent node, resulting in higher routing performance. Both principal and secondary roads are available for use. The simulation findings indicate that NCIoT algorithms outperform CBR protocols. Enhancements lead to a substantial 78% boost in network performance. In addition, the end-to-end latency dropped by 12.5%. The PISP methodology produces 5.9% more inquiry packets compared to alternative approaches. The algorithms are constructed and evaluated against academic ones.
IoT Guardian: A Novel Feature Discovery and Cooperative Game Theory Empowered...IJCNCJournal
Cyber intrusion attacks increasingly target the Internet of Things (IoT) ecosystem, exploiting vulnerable devices and networks. Malicious activities must be identified early to minimize damage and mitigate threats. Using actual benign and attack traffic from the CICIoT2023 dataset, this WORK aims to evaluate and benchmark machine-learning techniques for IoT intrusion detection. There are four main phases to the system. First, the CICIoT2023 dataset is refined to remove irrelevant features and clean up missing and duplicate data. The second phase employs statistical models and artificial intelligence to discover novel features. The most significant features are then selected in the third phase based on cooperative game theory. Using the original CICIoT2023 dataset and a dataset containing only novel features, we train and evaluate a variety of machine learning classifiers. On the original dataset, Random Forest achieved the highest accuracy of 99%. Still, with novel features, Random Forest's performance dropped only slightly (96%) while other models achieved significantly lower accuracy. As a whole, the work contributes substantial contributions to tailored feature engineering, feature selection, and rigorous benchmarking of IoT intrusion detection techniques. IoT networks and devices face continuously evolving threats, making it necessary to develop robust intrusion detection systems.
** Connect, Collaborate, And Innovate: IJCNC - Where Networking Futures Take ...IJCNCJournal
The International Journal of Computer Networks & Communications (IJCNC) is a bi monthly open access peer-reviewed journal that publishes articles which contribute new results in all areas of Computer Networks & Communications. The journal focuses on all technical and practical aspects of Computer Networks & data Communications. The goal of this journal is to bring together researchers and practitioners from academia and industry to focus on advanced networking concepts and establishing new collaborations in these areas.
Enhancing Traffic Routing Inside a Network through IoT Technology & Network C...IJCNCJournal
IoT networking uses real items as stationary or mobile nodes. Mobile nodes complicate networking. Internet of Things (IoT) networks have a lot of control overhead messages because devices are mobile. These signals are generated by the constant flow of control data as such device identity, geographical positioning, node mobility, device configuration, and others. Network clustering is a popular overhead communication management method. Many cluster-based routing methods have been developed to address system restrictions. Node clustering based on the Internet of Things (IoT) protocol, may be used to cluster all network nodes according to predefined criteria. Each cluster will have a Smart Designated Node. SDN cluster management is efficient. Many intelligent nodes remain in the network. The network design spreads these signals. This paper presents an intelligent and responsive routing approach for clustered nodes in IoT networks. An existing method builds a new sub-area clustered topology. The Nodes Clustering Based on the Internet of Things (NCIoT) method improves message transmission between any two nodes. This will facilitate the secure and reliable interchange of healthcare data between professionals and patients. NCIoT is a system that organizes nodes in the Internet of Things (IoT) by grouping them together based on their proximity. It also picks SDN routes for these nodes. This approach involves selecting one option from a range of choices and preparing for likely outcomes problem addressing limitations on activities is a primary focus during the review process. Predictive inquiry employs the process of analyzing data to forecast and anticipate future events. This document provides an explanation of compact units. The Predictive Inquiry Small Packets (PISP) improved its backup system and partnered with SDN to establish a routing information table for each intelligent node, resulting in higher routing performance. Both principal and secondary roads are available for use. The simulation findings indicate that NCIoT algorithms outperform CBR protocols. Enhancements lead to a substantial 78% boost in network performance. In addition, the end-to-end latency dropped by 12.5%. The PISP methodology produces 5.9% more inquiry packets compared to alternative approaches. The algorithms are constructed and evaluated against academic ones.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
Ethnobotany and Ethnopharmacology:
Ethnobotany in herbal drug evaluation,
Impact of Ethnobotany in traditional medicine,
New development in herbals,
Bio-prospecting tools for drug discovery,
Role of Ethnopharmacology in drug evaluation,
Reverse Pharmacology.
Palestine last event orientationfvgnh .pptxRaedMohamed3
An EFL lesson about the current events in Palestine. It is intended to be for intermediate students who wish to increase their listening skills through a short lesson in power point.
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
Students, digital devices and success - Andreas Schleicher - 27 May 2024..pptxEduSkills OECD
Andreas Schleicher presents at the OECD webinar ‘Digital devices in schools: detrimental distraction or secret to success?’ on 27 May 2024. The presentation was based on findings from PISA 2022 results and the webinar helped launch the PISA in Focus ‘Managing screen time: How to protect and equip students against distraction’ https://www.oecd-ilibrary.org/education/managing-screen-time_7c225af4-en and the OECD Education Policy Perspective ‘Students, digital devices and success’ can be found here - https://oe.cd/il/5yV
1. International Journal of Computer Networks & Communications (IJCNC) Vol.5, No.2, March 2013
Performance study of IEEE 802.16d under
Stanford University Interim (SUI)Channel
Abdul HashibSiddique1, A K M Arifuzzman2 and Mohammed Tarique3
1
Department of Electrical Engineering, The Petroleum Institute, Abu Dhabi, UAE
absiddique@pi.ac.ae
2
Department of EEE, American International University-Bangladesh, Dhaka, Bangladesh
arifuzzaman@aiub.edu
3
Department of Electrical Engineering, Ajman University of Science and Technology,
Fujairah, UAE
m.tarique@ajman.ac.ae
ABSTRACT
Wireless communications are subject to three major constraints: (i) a complex and unpredictable fading
channel, (ii) a scarce radio spectrum, and (iii) limitations on the power and the size of handheld terminals.
New technologies have been introduced and evolved based on these constraints. Among all of these
technologies Worldwide Interoperability for Microwave Access (WiMax) has drawn considerable attention
for broadband wireless communication. The WiMax technology has been standardized under IEEE 802.16d
and Orthogonal Frequency Division Multiplexing (OFDM) is the core of the WiMaxtechnology.In order to
investigate the performances of WiMax system a practical channel model is required. Many channel models
have been proposed to mimic a real world scenario including Stanford University Interim (SUI) channel.
This model has attracted considerable attentions of the researchers in the last few years. In this paper, the
performances in terms of bit error rate (BER) of IEEE 802.16d have been investigated by using different
SUI channel model. Some popular digital modulations like BPSK and QPSK have been considered. The
simulation results have been presented and compared for different SUI channel models.
KEYWORDS
WiMax, IEEE 802.16d, OFDM, Cyclic Prefix, BPSK, QPSK.
1. INTRODUCTION
In the recent years there has been a rapid growth in the Broadband Wireless Access (BWA)
networks. BWA is constantly acquiring popularity as an alternative of “last-mile” technology
instead of Digital Subscriber Line (DSL) and cable modems technologies.Because of its wireless
nature it is faster to deploy, easier to scale and more flexible. Therefore, this technology has great
potentiality to serve customers who have not been served before or who were not satisfied with
their wired broadband technologies. The performance of BWA is limited by multipath fading,
delay spread and co-channel interference [1].IEEE 802.16 standard and its associated industry
consortium WiMAX forum promise to offer the users a high speed wireless service over a large
area. The first version of the IEEE 802.16 standard operates in the range of 10–66GHz frequency
and requires a Line-of-Sight (LOS) communication between the transmitter and the receiver.The
later standards extended its operation through different PHY specifications to 211 GHz frequency
band enabling a Non Line-of-Sight (NLOS) communication. This later version uses a technique
DOI : 10.5121/ijcnc.2013.5211 137
2. International Journal of Computer Networks & Communications (IJCNC) Vol.5, No.2, March 2013
that can efficiently mitigate the performance impairments caused by the fading due to multipath
signal propagation. Utilizing the advantages of Orthogonal Frequency Division Multiplexing
(OFDM) technique the PHY layer is able to provide a robust broadband service in a hostile
wireless channel environment.The HiperMAN standard and the OFDM based physical layer of
IEEE 802.16 are nearly identical because OFDM based physical layer has been designed in close
cooperation with the European telecommunications standard High Performance Metropolitan
Area Network (HiperMAN). Both OFDM based physical layers comply with each other and
result in the emergence of a global OFDM system.AllWiMAX forum certified products for BWA
comply with the both of these standards.In this paper IEEE 802.16 OFDM physical layer has been
implemented using MatLab in order to investigate the system performances. Stanford University
Interim (SUI) channel has been used as the channel model. There have been numerous channel
models proposed for wireless communication system design. These channel models can be
broadly classified as (i) Indoor channel models, and (ii) Outdoor channel models [19-20]. UWV
channel models, Saleh-Valenzeula channel model, and IEEE 802.11 channel model are some of
the examples of indoor channel models. Whereas Filtered White Gaussian Noise (FWGN),
Clarke-Gans model, Modified Frequency Domain FWGN model, Time Domain FWGN model,
Jakes model, Ray based channel model, Frequency Selective channel model, and Stanford
University Interim (SUI) channel models are the examples of outdoor channel models.In this
investigation we chose SUI model because of its important characteristics. Some of the important
characteristics of SUI channel are as follows: (a) it has a higher path loss as compared to super
cell architecture, (b) it includes both macroscopic and microscopic fading effects, (c) it considers
both co-channel and adjacent channel interference, and (d) it takes account of high multipath
delay and Doppler spread [2]. The SUI channel also includesmany diversified parameters such as
terrain, antenna specification, wind speed or traffic range, and bandwidth. Erceg path loss model
has been used to represent a real world scenario.The K factor is a very important parameter of this
channel model, it is the ratio of power in the fixed component to the power in the variable
component.The K factor depends upon BTS and CPE heights, bandwidth, distance from the
antenna, environmental condition including wind, traffic, and season. However, SUI channel has
much more realistic approach as the K factor for all these 6 channels namely SUI-1, SUI-2, SUI-
3, SUI-4, SUI-5, and SUI-6 are very different [2]. The rest of this paper is organized as follows:
Section 2 briefly explains OFDM modulation technique. A comprehensive description of SUI
channel has been presented in section 3. The simulation model and results have been presented in
section 4. This paper is concluded with section 5.
2. OFDM MODULATION
The Orthogonal Frequency Division Multiplexing (OFDM) is a multi-carrier modulation (MCM).
OFDMwas introduced to support a very high data rate. The main advantage of OFDM is that it
can minimize the Inter Symbol Interference (ISI). It is also considered a spectrum efficient
modulation scheme originated from its orthogonal spectrum utilization. Some of the other
advantages of OFDM are: (a) it can cope with the multipath fading with less computational
complexity, (b) it is more resistant to frequency selective flat fading, (c) it uses computationally
efficient FFT and IFFT algorithm, (d) it is suitable for coherent demodulation, (e) it can ensure
the required Quality of Service (QoS) to the end users depending on the bandwidth, and (f) it can
assist diversity techniques (i.e., time diversity and frequency diversity). OFDM has some
disadvantages too. Some of the disadvantages of OFDM are: (a) it requires a strong
synchronization between the transmitter and the receiver, (b) it is very much sensitive to phase
noise and frequency offset, (c) it is not power efficient because the Fast Fourier Transform (FFT)
algorithm and Forward Error Correction (FEC)are always active, (d) it cannot take the advantages
of the diversity gain if few sub-carriers are allotted to each user,and (e) it requires a high peak to
average ration RF power amplifier to avoid amplitude noise.Like most multi-carrier modulation
the main principle of OFDM is also to divide into several parallel bit streams which are used to
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modulate several sub-carriers. The subcarrier which has a guard band ensures the non overlap of
each other. OFDM is a special form MCM technique, which employs densely spaced orthogonal
sub-carriers and overlapping spectrums. OFDM does not require the uses of bandpass filters as the
subcarrier is orthogonal in nature. So the bandwidth is very efficiently used without causing the Inter
Carrier Interference (ICI). The bandwidth can be reduced by removing the guard band and allowing the
subcarrier to overlap. It is still possible to recover the individual subcarrier though they overlapped in
the spectrum provided,if theorthogonality condition is maintained. By performing Fast Fourier
Transform (FFT) on the input bit stream the orthogonality is achieved.Because of the combination
of multiple low data rate subcarriers, OFDM provides a high data rate with a long symbol duration.
Depending on the channel coherence bandwidth it reduces or completely eliminates the effects of
Inter Symbol Interference (ISI), which is a common phenomenon in any multipath channel
environment with short symbol duration.The basic OFDM transmitter and receiver are illustrated
in Fig. 1.
(a) OFDM Transmitter
(b) OFDM Receiver
Fig. 1:(a) OFDM Transmitter and (b) OFDM receiver
In OFDM Discrete Fourier Transform (DFT) and Inverse Discrete Fourier Transform (IDFT) are
used to implement the orthogonal signals. Since all the orthogonal sub-carriers have finite
duration the spectrum of OFDM signal contains the summation of a set of sinc functions shifted
in the frequency domain as shown in Fig.2. The orthogonality of the subcarriers of an OFDM
system can be jeopardized when the same is sent through a multipath channel. A multipath
channel introduces Inter Symbol Interference (ISI) and Inter Carrier Interference (ICI). Cyclic
Prefix (CP) is added with the OFDM symbol to combat ISI and ICI. The CP contains a copy of
the last part of the OFDM symbol which is attached to the front of transmitted OFDM symbol.
The length of the CP must be longer than that of the maximum delay spread of the multipath
environment. To take the advantages of the CP certain position within the CP is chosen as the
sampling starting point denoted by Txat the receiver, which must satisfies a condition defined by
τmax< Tx< Tg,whereτmaxis the maximummultipath spread, Tg is the duration of a CP. Once the
above condition is satisfied, the ISI can be removed as the previous symbol will only have effect
over samples withinthe range [0, τmax]. The sampling period starting from Txwill encompass the
contribution from all the multipath components so that all the samples experience similar
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4. International Journal of Computer Networks & Communications (IJCNC) Vol.5, No.2, March 2013
Fig.2: The spectrum of OFDM signal.
channel condition and there is no ICI.OFDM system was designed to decrease the data rate at the
subcarrier level to satisfy the condition Ts˃˃τmax, where Ts is the duration of the symbol. By
using the Serial-to-Parallel (S/P) the symbol duration is increased(see Fig. 1) and hence the
multipath effects are reduced effectively. The insertion of higher valued CP helps to combat
multipath effects but at the same time it cancause higher loss of energy. Thus, a trade-off between
these two parameters must be maintained to obtain a reasonable system performance.The
performance of OFDM system is also limited by the constraints namely the availability of
bandwidth, required data rate, tolerable delay spread, and Doppler shifts. Some of the basic
design parameters of OFDM system are number of subcarriers, symbol duration and CP length,
subcarrier spacing, modulation type per subcarrier, and FEC coding.
3. THE SUI CHANNEL
In order to investigate the performances of OFDM based BWA an accurate channel model needs
to be considered. Usually all the wireless channels are characterized by path loss (including
shadowing), multipath delay spread, fading characteristics, Doppler spread, and co-channel and
adjacent channel interference.Ricean distribution can be used for characterization of narrow band
received signal fading. In this distribution the key parameter is the K-factor, which is defined as the
ratio of the “fixed” component power and the “scatter” component power . An empirical model was
derived from a 1.9 GHz experimental data set collected in a typical suburban environment for
transmitter antenna heights of approximately 20 m [7]. The model presented in [7] is as follows:
K = FsFhFbK 0du (1)
,where Fs is a seasonal factor,Fh is the receiving antenna height factor, Fbis the beam width factor,
Ko and γ are regression coefficients, u is a lognormal variable which has mean at 0 dB and a
standard deviation of 8.0dB. Some values of the parameters are Fs as 1.0 in summer and 2.5 in
winter respectively,Ko and γ are regression coefficients( Ko = 10; γ = -0.5). The receiving antenna
height factor Fh is defined by Fh= 0.46(h/3), where h is the receiving antenna height in meters, the
beam width factor Fbis defined by Fb = (b/17)-0.62, where bis in degrees.The empirical model
proposed in [7] has been confirmed by the experimental work presented in [8]. An independent
set of experimental data was acquired in San Francisco Bay Area at 2.4 GHz and with similar
antenna heights mentioned in [7] which has been reported in [8].It has also been shown that the
experimental data presented in [8] very closely matches with the model presented in [7].The
narrow band K-factor distribution was found to be lognormalwith the median as a simple function
of season, antenna height, antenna beam width, and distance. The standard deviation was found to
be about 8 dB. Using this model, it can be found that K-factor decreases as the distance from the
antenna and the antenna beam width is increased. One of our focus is to determine K-factor that
meets the requirement that 90% of all locations within a cell have to be served with 99.9%
reliability. Calculating the K-Factor is quite complex as it involves path loss, delay spread,
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5. International Journal of Computer Networks & Communications (IJCNC) Vol.5, No.2, March 2013
antenna correlation (if applicable), specific modem characteristics, and other parameters that
influence system performance. However an approximated value can be calculated with much
easier steps. First we select 90% of the users with the highest K-factors over the cell area.
Secondly we can obtain the approximate value by selecting the minimum K-factor within the set.
This value of K-factor can be close or equal to 0. In Fig. 3 shows fading cumulative distribution
functions (CDFs) for various K factors. For example, for K = 0 dB (i.e., linear K = 1) a 30 dB fade
occurs, which is very similar to a Rayleigh fading case (i.e., linear K = 0). The significance of
these fade probabilities actually depends on the system design such as whether diversity is
included and the quality of service (QoS) being offered etc.
Fig. 3: Ricean fading distribution
When multiple antennas are used at the transmitter and/or at the receiver, the channel can be
characterized by a matrix (i.e., Multi-Input-Multi-Output or MIMO in short) system, which is a
natural extension of the developments in antenna array based communication system.
The advantages of multiple receive antennas, such as gain and spatial diversity, have been known
and explained in some research works [9, 10, 11], the use of transmit diversity has also been
investigated in some recent works [12, 13]. The advantages of MIMO communication, has been
explained [6, 7, 8, 9, 10]. Channel models described above provide the basis for specifying
channels for a certain given scenario. There are many possible combinations of parameters to
obtain such channel descriptions. A set of 6 typical channels was selected for the three terrain
types that are typical of the continental US [13]. In this section we have presented SUI channel
models that we modified to account for 30o directional antennas. These models can be used for
simulation, design, development and testing of technologies suitable for fixed broadband wireless
applications. The model parameters were selected based upon the statistical models.SUI channel
models have 3 different types of terrain as shown in Table 1. Terrain C consisting of flat and light
tree density so that the effects of the obstruction are low in this case. SUI-1 and SUI-2 are the
channels taken into consideration to represent this type of terrain. The other two types of terrain
models are B and A. The terrain B is characterized by flat/moderate tree density. SUI-3 and SUI-
4 have been proposed for this type of terrain. The terrain A is characterized by a hilly area which
contains moderate to heavy tree density. SUI-5 and SUI-6 have been proposed for this type of
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6. International Journal of Computer Networks & Communications (IJCNC) Vol.5, No.2, March 2013
terrain. The SUI channels can also be classified as two more categories namely SUI channel with
low K-factor and SUI channel with high K-factor as shown in Table 2 and Table 3.
Table 1: Terrain of SUI model
Terrain Environmental Description SUI Model
C Flat/Light Tree Density SUI-1, SUI-2
B Flat/Moderate Tree Density SUI-3, SUI-4
A Hilly/Moderate to Heavy Tree Density SUI-5, SUI-6
Table 2: SUI channel with low K-factor
Doppler Low Delay Spread Moderate Delay High Delay Spread
Spread
Low SUI-3 SUI-5
High SUI-4 SUI-6
Table 3: SUI channel with high K-factor
Doppler Low Delay Spread Moderate Delay High Delay Spread
Spread
Low SUI-1, SUI-2 SUI-5
High
Table 2 and Table 3 depict that SUI-1 and SUI 2 have low delay spread because these two
channels represent the terrain type C which is characterized by low tree density. Hence there are
few obstructions in the signal propagation from a transmitter to a receiver.The other terrain types
have moderate to high delay spread. All these contributing to the value of K factor of the channel.
The general structure of SUI channel model is shown in Fig.4. This structure is generally used for
MIMO channels and this includes other configurations such as Single Input Single Output (SISO)
and Single Input Multiple Output (SIMO) as subsets. The structure is the same for the primary
and interfering signals in case of SUI channel. The basic components of the SUI channel models
are (a) input mixing matrix, (b) tapped delay line, and (c) output mixing matrix. The input
mixing matrix
Fig. 4: Transmitter and receiver block diagram for SUI channel
modelsthe correlation between the input signals if multiple transmitting antennas are used. The
tapped delay line matrixmodels the multipath fading of the channel.The multipath fading is
modeled as a tapped-delay line with 3 taps all having different delays. The gain is associated with
each tap which is characterized by a distribution (Ricean with a K-factor > 0, or Rayleigh with K-
factor = 0) and the maximum Doppler frequency. The output mixing matrix models the
correlation between the output signals in case we use multiple antennas.
Using the above general structure of the SUI Channel and thinking about the following scenario,
six SUI channels are have been proposed for our experiment, which are representative of the real
world channels. The following parameters (i) cell size:7 km, (ii) BTS antenna height: 30 m,(iii
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7. International Journal of Computer Networks & Communications (IJCNC) Vol.5, No.2, March 2013
)receive antenna height: 6 m, (iv) BTS antenna beam width: 120o, (v) receive antenna beam
width: omni-directional (360o) and directional (30o), (vi) verticalpolarization only, and (vii) 90%
cell coverage with 99.9% reliability at each area covered.For a 30o antenna beam width 2.3 times
smaller RMS delay spread is used to compare to an omni-directional antenna [15]. Consequently,
the second tap power is attenuated by an additional of 6 dB and the third tap power is attenuated
by additional 12 dB (effect of antenna pattern and delay remain the same). For the omni-
directional receive antenna the tap delays and the powers are consistent [16].
Table 4: Characteristic of SUI-1 Channel
Parameter Tap 1 Tap 2 Tap 3
Delay (μS) 0 0.4 0.9
Power (Omni-directional Antenna) 0 -15 -20
(dB) 4 0 0
90% K-factor (Omni-directional) 20 0 0
75% K-factor(Omni-directional)
Power (30ο Antenna) (dB) 0 -21 -32
90% K-factor (30ο) 16 0 0
75% K-factor(30ο) 72 0 0
Doppler Shift (Hz) 0.4 0.3 0.5
In Table 4 SUI-1 channel characteristics have been listed. In this type of channel model the
terrain used is low in density hence the tap delay is low in this type of channel. There have been
two types of antenna that are taken into account, firstly omni-directional and secondly a
directional antenna with a tilt of 300. In both the cases there are two different values of K factor
that have been considered. For this type of channel the antenna correlation is0.7, which results in
the reduction of the channel capacity [18].The other parameters of SUI-1 channel are antenna
correlation and K-factor. The value of antenna correlation under 0.5has very negligible effect on
the system capacity. The K-factor in this case is calculated and determined as 14 and 44.2 for
90% and 75% for directional antenna and for omni-directional respectively.In Table 5 shows the
SUI-2 channel parameters. In compare to SUI-1 channel, SUI-2 channel has higher delay for Tap
3. The antenna correlation is less than that of SUI-1 channel. SUI-2 has an antenna correlation of
0.5, which has almost no effect on the capacity of the model. The K-factor for omni-directional
antenna is the same as SUI-1, but in case of directional antenna the K-factor reduces
considerably.
Table 5: Characteristics of SUI-2 Channel
Parameter Tap 1 Tap 2 Tap 3
Delay (μS) 0 0.4 1.1
Power (Omni-directional Antenna) (dB) 0 -12 -15
90% K-factor (Omni-directional) 2 0 0
75% K-factor(Omni-directional) 11 0 0
Power (30ο Antenna) (dB) 0 -18 -27
90% K-factor (30ο) 8 0 0
75% K-factor(30ο) 36 0 0
Doppler Shift (Hz) 0.2 0.15 0.25
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Table 6: Characteristics of SUI-3 Channel
Parameter Tap 1 Tap 2 Tap 3
Delay (μS) 0 0.4 0.9
Power (Omni-directional Antenna) (dB) 0 -5 -10
90% K-factor (Omni-directional) 1 0 0
75% K-factor(Omni-directional) 7 0 0
Power (30ο Antenna) (dB) 0 -11 -22
90% K-factor (30ο) 3 0 0
75% K-factor(30ο) 19 0 0
Doppler Shift (Hz) 0.4 0.3 0.5
Table 6 shows the characteristic of SUI-3 which has a terrain type B. The tap delay in this case is
more than that of the earlier mentioned channel models. The system is considered again with
anOmni-directional and a directional antenna which have a K-factor of .5 and 1.6 for omni-
directional and 2.2 and 7 for directional for 90% and 75% respectively.
Table 7: Characteristic of SUI-4
Parameter Tap 1 Tap 2 Tap 3
Delay (μS) 0 1.5 4
Power (Omni-directional Antenna) (dB) 0 -4 -8
90% K-factor (Omni-directional) 0 0 0
75% K-factor(Omni-directional) 1 0 0
Power (30ο Antenna) (dB) 0 -10 -20
90% K-factor (30ο) 1 0 0
75% K-factor(30ο) 5 0 0
Doppler Shift (Hz) 0.2 0.15 0.25
Table 8: Charactaristics of SUI-5
Parameter Tap 1 Tap 2 Tap 3
Delay (μS) 0 4.0 10
Power (Omni-directional Antenna) 0 -5 -10
(dB) 0 0 0
90% K-factor (Omni-directional) 0 0 0
75% K-factor(Omni-directional) 2 0 0
50% K-factor (omni-directional)
Power (30ο Antenna) (dB) 0 -11 -22
90% K-factor (30ο) 0 0 0
75% K-factor(30ο) 2 0 0
50% K-factor (30ο) 7 0 0
Doppler Shift (Hz) 0.2 0.15 0.25
Table 7 characterizes SUI-4 channel model for type B terrain. SUI-4 has a further reduced
antenna correlation but the delay is more in this model. In omni-directional the delay is 1.257 µs
and for the directional with a tilt of 300 has a delay of 0.563 µs. The K-factor is further reduced in
this channel model. The K-factors are 0.2 and 0.6 in omni-directional antenna. The K-factors are 1
and 3.2 for directional antenna. Table 8 and 9 show the characteristics of SUI-5 and SUI-6
channel models. In this model the antenna corellation is the same as the previous three models.
But, the tap delay is less in SUI-5 as compared to SUI-6. The K- factors for both SUI-5 and SUI-6
model are identical.
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Table 9: Charactaristics of SUI-6
Parameter Tap 1 Tap 2 Tap 3
Delay (μS) 0 14.0 20
Power (Omni-directional Antenna) (dB) 0 -10 -14
90% K-factor (Omni-directional) 0 0 0
75% K-factor(Omni-directional) 0 0 0
50% K-factor (omni-directional) 1 0 0
Power (30ο Antenna) (dB) 0 -16 -26
90% K-factor (30ο) 0 0 0
75% K-factor(30ο) 2 0 0
50% K-factor (30ο) 5 0 0
Doppler Shift (Hz) 0.4 0.3 0.5
4. SUI SIMULATION MODEL AND RESULTS
The simulation model mainly consists of three main components namely transmitter, receiver and
channel. The channel used in the simulation is modeled as fading channel which will resemble the
real scenario. This structure of the model simulated corresponds to the physical layer of the IEEE
802.16 (2004) Wireless MAN OFDM air interface. In this setup, we have just implemented the
mandatory features specifications, while leaving the implementation of optional features for
future work [17]. Fig. 5 (a) shows the architecture of a OFDM transmitter and Fig.5 (b) shows an
OFDM receiver. In Fig. 5, the OFDM system treats the source symbols (e.g., the QPSK symbols)
at the transmitter to be in the frequency domain. These symbols are used as the inputs to the IFFT
block whichconverts the signal into the time domain. Each of the N (i.e., N is the number of
subcarriers) input orthogonal sinusoids for the IFFT have a different frequency. The IFFT block
modulates the N sinusoids onto N orthogonal subcarriers and provides an OFDM symbol. To
overcome the overlapping of data cyclic prefix is inserted and then D/A converts it to analog one.
After that this time-domain signal is transmitted across the channel. At the receiving end,
receiving antenna receives an independent copy of the transmitted signal. Then the A/D converts
that signal into digital one and cyclic prefix is removed as well. After passing through the FFT
block the received signal transforms into the frequency domain. When we plotted the FFT output
samples in the complex plain then it forms a constellation (such as QPSK). Before the transmission of data
the cyclic prefix (CP) is added to the data. This adding of CP helps in resisting against ISI and
multipath propagation [16].IEEE 802.16 allows the insertion of cyclic prefix with various lengths
such as 1/4, 1/8, 1/16 and 1/32. The length of the cyclic prefix must be chosen which longer than
the maximum delay spread of the target multipath environment. The transmitted data is then fed
into the SUI channels for operation. At the receiver side the cyclic prefix is removed before doing
any further processing of the signal.
Input Serial to IFFT Parallel to serial
Data Parallel converter
converter
Antenna
D/A Guard time
Converter insertion
(a)Transmitter
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Antenna
A/D Guard time
Receiver
Converter extraction
Serial to parallel FFT
converter
Output Parallel to
Data serial
converter
(b)Receiver
Fig.5: OFDM transmitter and receiver in SUI Channel
A modular have been developed using MatLab for our simulation work. The program contains the
initialization parameters and input data. At the time of initialization are the number of simulated
OFDM symbols, CP length, modulation, and the range of SNR values and SUI channel model for
simulation can be set. In Table 10 some of the simulation parameters are listed. In Fig. 6 the
flowchart of the program used has been shown. The input data stream are randomly generated
where as the output variables are available in MatLab workspace while BER values for different
SNR are stored in the text files which facilitate to draw plots. Each single block of the transmitter
is tested with its counterpart of the receiver side to confirm each block is working perfectly.
Table 10: Simulation parameters
Parameter Value
FFT size. 256
Number of used subcarriers. 192
FFT Sampling frequency 20MHz
Ratio of Guard time to useful symbol time 1/4 ,1/8, 1/16, 1/32
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Fig. 6: Program flowchart
The simulation results of SUI-1 channel are shown in Fig. 7. In these simulations Binary Phase
Shift Keying (BPSK) modulation was used and the cyclic prefix was varied. The theoretical result
is also plotted in the same figure for comparison. Fig.7 shows that the BER decreases as the SNR
(Eb /N) increases as usual. But, the cyclic Prefix plays an important role on the system
performance. It is clearly shown that as the CP is increased for a given SNR the BER decreases
for a given SNR. The simulation results for SUI-2 channel model are presented in Fig.8. The
system performances are very similar to SUI-1 channel model. The CP=1/4 is the best choice for
SUI-2 model. Unlike SUI-1 channel the other cyclic prefixes like 1/8, 1/16, and 1/32 perform
almost in the same manner. For small SNR the performances are similar for 1/18, 1/16, and 1/32
CPs. But, the system performance is the best for CP=1/8.
The simulations are repeated for SUI-3 channel and the results are shown in Fig. 9. This figure
shows that the cyclic prefixes play no significant role on the system performances. Italso shows
that the BER performance of the system are almost similar for CP=1/8, 1/16 and 1/32 although
they have different effects for SUI-1 and SUI-2 channels.
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BER of the received symbols. ( SUI=1,BW =20MHz and modulation of BPSK )
0
10
-1
10
BER
-2
10
-3
10
CP=1/4
10
-4 CP=1/8
CP=1/16
CP=1/32
-5 Theoretical
10
0 5 Eb/N 10 15
Fig. 7: Bit Error Rate of SUI-1 channel with BPSK
B E R of the rec eiv ed s y m bols . ( S UI= 2,B W = 20M Hz and m odulation of B P S K )
0
10
CP =1/ 4
CP =1/ 8
CP =1/ 16
CP =1/ 32
Theoret ic al
-1
10
BER
-2
10
-3
10
-4
10
0 5 10 15
Eb/N
Fig.8: Bit Error Rate of SUI-2 channel with BPSK
BER of the received symbols. ( SUI=3,BW=20MHz and modulation of BPSK )
0
10
CP=1/8
CP=1/16
10
-1 CP=1/32
Theoretical
BER CP=1/4
-2
10
-3
10
-4
10
-5
10
0 5 10 15
Eb/N
Fig.9: Bit Error Rate of SUI-3 channel with BPSK
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The BER rate performances for SUI-4 channel are shown in Fig. 10. It shows that the optimal CP
for SUI-4 channel is CP=1/4. The other most significant CP is CP=1/8. The CP=1/16 and
CP=1/32 have no effects on the BER at all. We also consider SUI-5 and SUI-6 in our
simulations. The results are presented in Fig. 11 and Fig. 12. These figures show that the cyclic
prefixes have no effects on the system performances. The perfect matching of the curves confirms
our claims. In our investigation we also considered Quadrature Phase Shift Keying (QPSK)
modulation. We conducted similar simulations as mentioned before but we changed the
modulation to QPSK. The simulation results for QPSK with SUI-1 channel are presented in Fig.
13. The results show that CP=1/8 is the best choice for SUI-1 channel. The CP=1/16 is a poor
choice for SUI-1.
BER of the received symbols. ( SUI=4,BW=20MHz and modulation of BPSK )
0
10
BER
-1
10
-2
10
CP=1/4
CP=1/8
CP=1/16
CP=1/32
Theoretical
-3
10
0 5 10 15
Eb/N
Fig.10: Bit Error Rate of SUI-4 channel with BPSK
The system performances of SUI-2 channels are shown in Fig. 14. This figure shows that CPs
play important roles on the system performance. Different CPs has different impacts on the
system performances. For example, it is shown that CP=1/8 is the best choice for SUI-2 channel.
On the other than CP=1/32 has little effect on the system performance.
BER of the received symbols. ( SUI=5,BW=20MHz and modulation of BPSK )
0
10
BER
-1
10
-2
10
CP=1/4
CP=1/8
CP=1/16
CP=1/32
Theoretical
-3
10
0 5 10 15
Eb/N
Fig.11: Bit Error Rate of SUI-5 channel with BPSK
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B E R of the rec eived s y m bols . ( S U I= 6,B W = 20M H z and m odulation of B P S K )
0
10
BER
-1
10
-2
10
C P = 1/4
C P = 1/8
C P = 1/16
C P = 1/32
Theoretic al
-3
10 Eb/N
0 5 10 15
Fig.12: Bit Error Rate of SUI-6 channel with BPSK
B E R of the rec eived s y m bols . ( S UI= 1,B W = 20M Hz and m odulation of Q P S K )
0
10
-1
10
BER
-2
10
-3
10
CP = 1/4
-4 CP = 1/8
10
CP = 1/16
CP = 1/32
Theoretic al
-5
10
0 5 10 15
Eb/N
Fig.13: Bit Error Rate of SUI-1 channel with QPSK
BER of the received symbols. ( SUI=2,BW=20MHz and modulation of QPSK )
0
10
-1
10
BER
-2
10
-3
10
CP=1/4
-4 CP=1/8
10
CP=1/16
CP=1/32
Theoretical Eb/N
-5
10
0 5 10 15
Fig.14: Bit Error Rate of SUI-2 channel with QPSK
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B E R o f t h e re c e ive d s y m b o ls . ( S U I= 3 , B W = 2 0 M H z a n d m o d u la t io n o f Q P S K )
0
10
-1
10
BER
-2
10
-3
C P = 1/4
10 C P = 1/8
C P = 1/16
C P = 1/32
T h e o re t ic a l
-4
10
0 5 10 15
E /N
Fig.15: Bit Error Rate ofbSUI-3 channel with QPSK
The simulation results for SUI-3 channel are shown in Fig. 15. This figure shows that CP=1/32
and CP=1/16 have little effects on the system performance. But, CP=1/8 is the best choice for
SUI-3 model. The CP=1/4 is also a good choice for SUI-3 channel.We also repeated the
simulations for SUI-4, SUI-5 and SUI-6 channels. We found similar results like those of BPSK
modulation as shown before. Hence, we did not repeat the results here. But, the major finding
from those simulation results is that the CPshas little effect on SUI-4, SUI-5 and SUI-6 channels.
5. CONCLUSIONS
In this paper the performances of OFDM based IEEE 802.16d have been investigated. Different
SUI channel models have been considered in this investigation. Some important parameters of
OFDM like cyclic prefixes have been varied. Two modulation schemes namely BPSK and QPSK
have been considered. The simulation results show that choosing an appropriate CP depends on
the given conditions. Theoretically higher CP length should be chosen to cope with ISI and hence
to improve system performance. But, in this investigation we show that CP should be chosen
depending on the channel modes and the modulation schemes. For example, CP=1/4 is the best
choice for most the cases addressed in this paper. But, CP=1/8 outperforms CP=1/4 in some cases
like when we used QPSK and SUI-3 channel model. So, the appropriate CP should be chosen
depending on the channel and modulation used.
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AUTHORS
Abdul HashibSiddiqueis agraduate student member of IEEE. He completed his B.Sc.
Engineering degree from American International University-Bangladesh in 2008. He also
completed his Master of Telecommunication(MTEL) degree from the same university in
2010. He has also completed his Ma ster of Science in Electrical Engineering from the
Petroleum Institute, Abu Dhabi, United Arab Emirates in 2013. He had worked as a Lecturer
in Electrical and Electronic Engineering department from 2009 to 2010. He has more than 10
journal and conference papers to his credential.His research interests include Smart Power Grid, Distributed
Generator, Wireless Power Transfer, Wireless Communication, and channel modeling.
A K M Arifuzzmanis a Lecturer at American International University- Bangladesh
(AIUB) in EEE Department. He has been completed his B.Sc. Engineering degree in
December 2010. He is a member of IEEE. He is actively involved in research activities in
the field of Electrical Engineering. He conducted several investigations in this field. He
has been published his research works in several journals. His research interests are DSP
signal processing, wireless communication, nano-electronics, bio-sensor etc.
Mohammed Tarique completed his B.Sc. Engineering degree from Bangladesh University
of Science and Technology (BUET) in 1992. He completed his MS degree from Lamar
University, Texas, USA in 2001. He completed his PHD degree from the University of
Windsor, Windsor, Canada in 2007. He has both industrial and academic experiences.
Currently he is working with the Department of Electrical Engineering, Ajman University of
Science and Technology (AUST), Fujairah, United Arab Emirates. He had also worked with
the Department of Electrical and Electronic Engineering, American International University-
Bangladesh since 2007-2011. He supervised 7 Master students. His research works have been published in
prestigious journal. He also presented his works in several conferences held in USA, Canada and Europe.
His research interests are in Wireless Communication, Digital Signal Processing, Ad Hoc networks, Sensor
Networks, and Antenna design.
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