Wimax technology has reshaped the framework of broadband wireless internet
service. It provides the internet service to unconnected or detached areas such as east South
Africa, rural areas of America and Asia region. Full duplex helpers employed with one of
the relay stations selection and indexing method that is Randomized Distributed Space Time
are used to expand the coverage area of primary Wimax station. The basic problem was
identified at cell edge due to weather conditions (rain, fog), insertion of destruction because
of multiple paths in the same communication channel and due to interference created by
other users in that communication. It is impractical task for the receiver station to decode
the transmitted signal successfully at the cell edges, which increases the high packet loss and
retransmissions. But Wimax is a outstanding technology which is used for improving the
quality of internet service and also it offers various services like Voice over Internet
Protocol, Video conferencing and Multimedia broadcast etc where a little delay in packet
transmission can cause a big loss in the communication. Even setup and initialization of
another Wimax station nearer to each other is not a good alternate, where any mobile
station can easily handover to another base station if it gets a strong signal from other one.
But in rural areas, for few numbers of customers, installation of base station nearer to each
other is costlier task. In this review article, we present a scheme using R-DSTC technique to
choose and select helpers (relay nodes) randomly to expand the coverage area and help to
mobile station as a helper to provide secure communication with base station. In this work,
we use full duplex helpers for better utilization of bandwidth.
An Approach to Improve the Quality of Service in OFDMA Relay Networks via Re-...iosrjce
With the next-generation cellular networks making a transition toward smaller cells, two-hop
orthogonal frequency-division multiple access (OFDMA) relay networks have become a dominant, mandatory
component in the 4G standards (WiMAX802.16j, 3GPP LTE-Adv.). Here we are using the multicasting strategy
Given the growing importance of multimedia broadcast and multicast services (MBMS) in 4G networks, the
latter forms the focus of this project. The main aim of this project is to improve the performance of the OFDMA
based relay networks. The OFDMA transmission Scheme is a widely accepted scheme for improving the quality
and speed of communication over the 4G cellular network. There are two different models designed for OFDMA
relay networks .Distributed (DP) and Contiguous (CP) permutations. We are checking the performance of two
algorithms The linear programming algorithm and the greedy algorithm by using two models of OFDMA for
multicast scheduling and after performance evaluation we select the best model and the algorithm for
transmission. We further improve the throughput via retransmission of lost packets during data transfer over the
specified network. We can detect the packet loss by packet synchronization technique and a request will be sent
by the destination for re-sending the lost packets which is called as Re-Transmission.[1]
DESIGN OF A COMPACT CIRCULAR MICROSTRIP PATCH ANTENNA FOR WLAN APPLICATIONS pijans
This paper presents the design of a compact circular microstrip patch antenna for WLAN applications which covers the band 5.15 to 5.825 GHz. The antenna is designed using 1.4mm thick FR-4 (lossy)substrate with relative permittivity 4.4 and a microstrip line feed is used. The radius of the circular patch is chosen as 7.62mm. To reduce the size and enhance the performance of the proposed antenna, a circular slot is loaded on circular patch and a square slot is etched on the ground plane of dimension 30mm×30mm. Design of the antenna is carried out using CST Microsoft Studio Sonimulation Software. The proposed antenna resonates at 5.5 GHz with a wider bandwidth of 702 MHz and it provides low return loss of -31.58 dB, good gain of 3.23 dB and directivity of 4.28 dBi and high efficiency of around 79% against the resonance frequency. The geometry of the proposed circular antenna with reduced size and its various performance parameters such as return loss, bandwidth, VSWR, gain, directivity, efficiency and radiation pattern plots are presented and discussed.
Modelling and QoS-Achieving Solution in full-duplex Cellular SystemsIJCNCJournal
The global bandwidth scarcity and the ever-growing demand for fast wireless services have motivated the quest for new techniques that enhance the spectral efficiency (SE) of wireless systems. Most conventional SE increasing methods (e.g., adaptive modulation and coding) have already been exhausted. Single-channel full-duplex (SCFD) communication is a new attractive approach in which each node may simultaneously receive and transmit over the same frequency channel, and thus, it has the potential to double the current SE figures. In this paper, we derive a model for the signal-to-interference-plus-noise ratio (SINR) in a SCFD-based cellular system with imperfect self-interference cancellation. Furthermore, given a set of uplink and downlink quality of service requirements, we answer the following two fundamental questions. First, is this set achievable in the SCFD-based cellular system? Second, if the given set is achievable, what is the optimal achieving policy? To that end, we provide a unified model for the SCFD-based cellular system, and give insights in the matrix of interference channel gains. Simulation results suggest that depending on the locations of the users, a combination of full-duplex and half-duplex modes over the whole network is more favourable policy
A small vessel detection using a co-located multi-frequency FMCW MIMO radar IJECEIAES
Small vessels detection is a known issue due to its low radar cross section (RCS). An existing shore-based vessel tracking radar is for long-distance commercial vessels detection. Meanwhile, a vessel-mounted radar system known for its reliability has a limitation due to its single radar coverage. The paper presented a co-located frequency modulated continuous waveform (FMCW) maritime radar for small vessel detection utilising a multiple-input multiple-output (MIMO) configuration. The radar behaviour is numerically simulated for detecting a Swerling 1 target which resembles small maritime’s vessels. The simulated MIMO configuration comprised two transmitting and receiving nodes. The proposal is to utilize a multi-frequency FMCW MIMO configuration in a maritime environment by applying the spectrum averaging (SA) to fuse MIMO received signals for range and velocity estimation. The analysis was summarised and displayed in terms of estimation error performance, probability of error and average error. The simulation outcomes an improvement of 2.2 dB for a static target, and 0.1 dB for a moving target, in resulting the 20% probability of range error with the MIMO setup. A moving vessel's effect was observed to degrade the range error estimation performance between 0.6 to 2.7 dB. Meanwhile, the proposed method was proven to improve the 20% probability of velocity error by 1.75 dB. The impact of multi-frequency MIMO was also observed to produce better average error performance.
Device to Device Communications will enable on cellular 4G/5G networks soon, There are many research aspects in D2D Communications,
Mode Selection
Network Coding
MIMO
Multi-Hop
the most complicated Interference scenarios are coming
An Approach to Improve the Quality of Service in OFDMA Relay Networks via Re-...iosrjce
With the next-generation cellular networks making a transition toward smaller cells, two-hop
orthogonal frequency-division multiple access (OFDMA) relay networks have become a dominant, mandatory
component in the 4G standards (WiMAX802.16j, 3GPP LTE-Adv.). Here we are using the multicasting strategy
Given the growing importance of multimedia broadcast and multicast services (MBMS) in 4G networks, the
latter forms the focus of this project. The main aim of this project is to improve the performance of the OFDMA
based relay networks. The OFDMA transmission Scheme is a widely accepted scheme for improving the quality
and speed of communication over the 4G cellular network. There are two different models designed for OFDMA
relay networks .Distributed (DP) and Contiguous (CP) permutations. We are checking the performance of two
algorithms The linear programming algorithm and the greedy algorithm by using two models of OFDMA for
multicast scheduling and after performance evaluation we select the best model and the algorithm for
transmission. We further improve the throughput via retransmission of lost packets during data transfer over the
specified network. We can detect the packet loss by packet synchronization technique and a request will be sent
by the destination for re-sending the lost packets which is called as Re-Transmission.[1]
DESIGN OF A COMPACT CIRCULAR MICROSTRIP PATCH ANTENNA FOR WLAN APPLICATIONS pijans
This paper presents the design of a compact circular microstrip patch antenna for WLAN applications which covers the band 5.15 to 5.825 GHz. The antenna is designed using 1.4mm thick FR-4 (lossy)substrate with relative permittivity 4.4 and a microstrip line feed is used. The radius of the circular patch is chosen as 7.62mm. To reduce the size and enhance the performance of the proposed antenna, a circular slot is loaded on circular patch and a square slot is etched on the ground plane of dimension 30mm×30mm. Design of the antenna is carried out using CST Microsoft Studio Sonimulation Software. The proposed antenna resonates at 5.5 GHz with a wider bandwidth of 702 MHz and it provides low return loss of -31.58 dB, good gain of 3.23 dB and directivity of 4.28 dBi and high efficiency of around 79% against the resonance frequency. The geometry of the proposed circular antenna with reduced size and its various performance parameters such as return loss, bandwidth, VSWR, gain, directivity, efficiency and radiation pattern plots are presented and discussed.
Modelling and QoS-Achieving Solution in full-duplex Cellular SystemsIJCNCJournal
The global bandwidth scarcity and the ever-growing demand for fast wireless services have motivated the quest for new techniques that enhance the spectral efficiency (SE) of wireless systems. Most conventional SE increasing methods (e.g., adaptive modulation and coding) have already been exhausted. Single-channel full-duplex (SCFD) communication is a new attractive approach in which each node may simultaneously receive and transmit over the same frequency channel, and thus, it has the potential to double the current SE figures. In this paper, we derive a model for the signal-to-interference-plus-noise ratio (SINR) in a SCFD-based cellular system with imperfect self-interference cancellation. Furthermore, given a set of uplink and downlink quality of service requirements, we answer the following two fundamental questions. First, is this set achievable in the SCFD-based cellular system? Second, if the given set is achievable, what is the optimal achieving policy? To that end, we provide a unified model for the SCFD-based cellular system, and give insights in the matrix of interference channel gains. Simulation results suggest that depending on the locations of the users, a combination of full-duplex and half-duplex modes over the whole network is more favourable policy
A small vessel detection using a co-located multi-frequency FMCW MIMO radar IJECEIAES
Small vessels detection is a known issue due to its low radar cross section (RCS). An existing shore-based vessel tracking radar is for long-distance commercial vessels detection. Meanwhile, a vessel-mounted radar system known for its reliability has a limitation due to its single radar coverage. The paper presented a co-located frequency modulated continuous waveform (FMCW) maritime radar for small vessel detection utilising a multiple-input multiple-output (MIMO) configuration. The radar behaviour is numerically simulated for detecting a Swerling 1 target which resembles small maritime’s vessels. The simulated MIMO configuration comprised two transmitting and receiving nodes. The proposal is to utilize a multi-frequency FMCW MIMO configuration in a maritime environment by applying the spectrum averaging (SA) to fuse MIMO received signals for range and velocity estimation. The analysis was summarised and displayed in terms of estimation error performance, probability of error and average error. The simulation outcomes an improvement of 2.2 dB for a static target, and 0.1 dB for a moving target, in resulting the 20% probability of range error with the MIMO setup. A moving vessel's effect was observed to degrade the range error estimation performance between 0.6 to 2.7 dB. Meanwhile, the proposed method was proven to improve the 20% probability of velocity error by 1.75 dB. The impact of multi-frequency MIMO was also observed to produce better average error performance.
Device to Device Communications will enable on cellular 4G/5G networks soon, There are many research aspects in D2D Communications,
Mode Selection
Network Coding
MIMO
Multi-Hop
the most complicated Interference scenarios are coming
Efficient Channel Assignment Schemes In 802.11 WLANIJSRD
A wireless local area network (LAN) is a flexible data communications system implemented as an extension to, or as an alternative for, a wired LAN. Wireless Local Area Networks (WLANs) are having tremendous growth & becoming increasingly popular. The planning of wireless local area network (WLAN) infrastructures that supply large buildings or areas requires the consideration of many aspects (coverage, different traffic densities, interference, cost minimization, network throughput) and therefore is a difficult task if done manually. The performance of WLAN can be greatly improved by efficient channel assignment. This paper presents a survey on efficient channel assignment algorithms in WLAN’s. The survey is concluded with various research issues open for further study.
Computer networks have experienced an explosive growth over the past few years, which has lead to some severe congestion problems. Reliable protocols like TCP works well in wired networks where loss occurs mostly because of congestion. However, in wireless networks, loss occurs because of bit rates and handoffs too. TCP responds all losses by congestion control and avoidance algorithms, which results in degradation of TCP’s End-To-End performance in wireless networks. This paper discusses different issues and problems regarding use of TCP in wireless networks and provides comprehensive survey of various schemes to improve performance of TCP in Wireless Networks.
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.
A novel optimal small cells deployment for next-generation cellular networks IJECEIAES
Small-cell-deployments have pulled cellular operators to boost coverage and capacity in high-demand areas (for example, downtown hot spots). The location of these small cells (SCs) should be determined in order to achieve successful deployments. In this paper, we propose a new approach that optimizes small cells deployment in cellular networks to achieve three objectives: reduce the total cost of network installation, balancing the allocation of resources, i.e. placement of each SC and their transmitted power, and providing optimal coverage area with a lower amount of interference between adjacent stations. An accurate formula was obtained to determine the optimum number of SC deployment (NSC). Finally, we derive a mathematical expression to calculate the critical-handoff-point (CHP) for neighboring wireless stations.
A CELLULAR BONDING AND ADAPTIVE LOAD BALANCING BASED MULTI-SIM GATEWAY FOR MO...pijans
As it is well known, the QoS(quality of service) provided by mobile Internet access point devices is far from
the QoS level offered by the common ADSL modem-router due to several reasons: in fact, mobile Internet
access networks are not designed to support real-time data traffic because of several drawbacks
concerning the wireless medium such as resource sharing, traffic congestion, radio link coverage etc.,
which impact directly such parameters as delay, jitter, and packet loss rate that are strictly connected to
the quality of user experience. The main scope of the present paper is to introduce a dual USIM HSPA
gateway for ad hoc and sensors networks thanks to which it will be possible to guarantee a QoS suitable
for a series of network-centric application such as real-time communications and monitoring, video
surveillance, real-time sensor networks, telemedicine, vehicular and mobile sensor networks and so on. The
main idea is to exploit multiple radio access networks in order to enhance the available end-to-end
bandwidth and the perceived quality of experience. The scope has been reached by combining multiple
radio access with dynamic load balancing and the VPN (virtual private network) bond technique.
This is a presentation I did at the pre-Master studies at Ain shams University. It\'s about algorithms and techniques of call admission when a mobile node moves among cell in a wireless network.
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.
The peer-reviewed International Journal of Engineering Inventions (IJEI) is started with a mission to encourage contribution to research in Science and Technology. Encourage and motivate researchers in challenging areas of Sciences and Technology.
An approach to control inter cellular interference using load matrix in multi...eSAT Journals
Abstract
This paper deals with reduction of inter cellular interference in Multi-carrier communication systems. In the past, Load Matrix(LM) is proposed to allocate power to different users in a network based upon Signal to noise plus interference ratio (SNIR) so as to reduce inter cellular interference and is observed for single carrier systems. In Multi carrier systems the SNIR is affected distinctly in each carrier thus a single SNIR for power allocation is not optimal. In this paper, to obtain the optimization of power allocation in Multi-Carrier system, Load Matrix coding with bifurcated SNIR (LM-BFSNIR) is proposed. Using this approach it is observed that inter cellular interference is reduced better when compared to a single carrier system evaluated over a 3GPP-LTE standard.
Keywords−Power allocation, Inter cellular interference, Multi-Carrier mobile Communication system.
Improving The Performance Of Multiuser OFDM Wireless System With UWB ChannelIJTET Journal
The multi user OFDM system can be used to produce a highly flexible and effective communication
system. In the existing multi user OFDM system, resource allocation to each user is the major problem. Also the existing
multi user OFDM system uses frequency diversity technique that requires sparse bandwidth and multiple receivers
improving the complexity. In order to increase the system performance, the proposed system allows multiple user data to
be multiplexed together to form a single OFDM symbol where the resources are allocated equally to all users. The
proposed multiuser OFDM system achieves double the capacity and better performance in terms of Signal-to-Noise Ratio
and Bit Error Rate of a single user OFDM system and the UWB channel is used to securely transmit the data through the
channel. Also, the proposed system reduces the receiver complexity by using polarization diversity to receive the
multipath components for multiple users.
As a consequence of the proliferation of smart phones and tablets, data traffic is growing significantly, both on the radio access links and the backhaul infrastructure of mobile operators’ networks. And although LTE and LTE Advanced offer higher data traffic throughput than that of 3G, given to their wider allocated bandwidths, the combined capacities of even these networks is not sufficient to meet projected future capacity demands.
The conventional solution to increasing the capacity of LTE mobile networks includes splitting macro-cells and/or adding more sites. Both of these solutions require high CAPEX and OPEX, so mobile operators are seeking new and cost effective ways of increasing their network capacity. One solution is to deploy small-cell base stations (BSs) within their existing macro-cellular networks, an approach referred to as Heterogeneous Networks.
It is well known that a HetNet not only increases the network capacity, but also provides better coverage and enhances the user’s experience. These benefits are achieved by offloading data traffic dynamically from MCBSs to SCBSs using an algorithm based on several parameters such as the characteristics of the traffic, the required QoS and network
Advanced antenna techniques and high order sectorization with novel network t...ijwmn
Mobile operators commonly use macro cells with trad
itional wide beam antennas for wider coverage in th
e
cell, but future capacity demands cannot be achieve
d by using them only. It is required to achieve max
imum
practical capacity from macro cells by employing hi
gher order sectorization and by utilizing all possi
ble
antenna solutions including smart antennas. This pa
per presents enhanced tessellation for 6-sector sit
es
and proposes novel layout for 12-sector sites. The
main target of this paper is to compare the perform
ance
of conventional wide beam antenna, switched beam sm
art antenna, adaptive beam antenna and different
network layouts in terms of offering better receive
d signal quality and user throughput. Splitting mac
ro cell
into smaller micro or pico cells can improve the ca
pacity of network, but this paper highlights the
importance of higher order sectorization and advanc
e antenna techniques to attain high Signal to
Interference plus Noise Ratio (SINR), along with im
proved network capacity. Monte Carlo simulations a
t
system level were done for Dual Cell High Speed Dow
nlink Packet Access (DC-HSDPA) technology with
multiple (five) users per Transmission Time Interva
l (TTI) at different Intersite Distance (ISD). The
obtained results validate and estimate the gain of
using smart antennas and higher order sectorization
with
proposed network layout.
Handover for 5G Networks using Fuzzy Logic: A ReviewAI Publications
The future organization world will be inserted with various ages of remote advances, like 4G and 5G. Simultaneously, the advancement of new gadgets outfitted with different interfaces is filling quickly as of late. As a result, the upward handover convention is created to give pervasive availability in the heterogeneous remote climate. Handover might be a fundamental a piece of any remote Mobile Communication Network. It is a way of mobile communication and portable communication during which cellular broadcast is relocate from one base station to another without losing connection to the mobile communication. Handover is one problem on Wireless Network (WN) and to unravel this problem various sorts of HO methods utilized in network. Fuzzy logic, Machine Learning and Optimization are the handover solving methods that are studied during this paper. This paper is a review of the handoff techniques. Fuzzy logic is that the best technique to unravel the HO problem and it's further implemented in 4G/5G network.
Security in Mobile Ad Hoc Network became very important due to the nature of wireless communication
between the nodes and the rapid movement of node which make Mobile Ad hoc Network vulnerable to
Attackers. Jamming is a DoS attack’s special category used in wireless networks. The attacker disrespects
the medium access control (MAC) protocol and transmits on the shared channel; either periodically or
continuously to target all or some communication, respectively. Distributed coordination function (DCF)
and Point coordination function (PCF) are the two different media access control (MAC) mechanisms
which are specified by the IEEE 802.11standard. PCF can achieve higher throughput than DCF due to the
nature of contention-free, therefore, this paper investigate the impact of PCF when integrated into the
TORA – Based MANET and how it can improve the performance of the network. OPNET – Based
simulation scenarios were created and the simulation was run and the results were collected which
investigate that PCF provided a good functionality to improve deficiency caused by the Jammers this by
increasing the throughput and decreasing the delay which is affected by the Jammers. PCF was a good
improvement with different levels of Jammers’ transmission power.
Privacy-preservation for sensitive data has become a challenging issue in cloud computing.Threat modeling as a part of requirements engineering in secure software development provides a structured approach for identifying attacks and proposing countermeasures against the
exploitation of vulnerabilities in a system. This paper describes an extension of Cloud Privacy Threat Modeling (CPTM) methodology for privacy threat modeling in relation to processing sensitive data in cloud computing environments. It describes the modeling methodology that involved applying Method Engineering to specify characteristics of a cloud privacy threat modeling methodology, different steps in the proposed methodology and corresponding products. We believe that the extended methodology facilitates the application of a privacy preserving cloud software development approach from requirements engineering to design
Efficient Channel Assignment Schemes In 802.11 WLANIJSRD
A wireless local area network (LAN) is a flexible data communications system implemented as an extension to, or as an alternative for, a wired LAN. Wireless Local Area Networks (WLANs) are having tremendous growth & becoming increasingly popular. The planning of wireless local area network (WLAN) infrastructures that supply large buildings or areas requires the consideration of many aspects (coverage, different traffic densities, interference, cost minimization, network throughput) and therefore is a difficult task if done manually. The performance of WLAN can be greatly improved by efficient channel assignment. This paper presents a survey on efficient channel assignment algorithms in WLAN’s. The survey is concluded with various research issues open for further study.
Computer networks have experienced an explosive growth over the past few years, which has lead to some severe congestion problems. Reliable protocols like TCP works well in wired networks where loss occurs mostly because of congestion. However, in wireless networks, loss occurs because of bit rates and handoffs too. TCP responds all losses by congestion control and avoidance algorithms, which results in degradation of TCP’s End-To-End performance in wireless networks. This paper discusses different issues and problems regarding use of TCP in wireless networks and provides comprehensive survey of various schemes to improve performance of TCP in Wireless Networks.
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.
A novel optimal small cells deployment for next-generation cellular networks IJECEIAES
Small-cell-deployments have pulled cellular operators to boost coverage and capacity in high-demand areas (for example, downtown hot spots). The location of these small cells (SCs) should be determined in order to achieve successful deployments. In this paper, we propose a new approach that optimizes small cells deployment in cellular networks to achieve three objectives: reduce the total cost of network installation, balancing the allocation of resources, i.e. placement of each SC and their transmitted power, and providing optimal coverage area with a lower amount of interference between adjacent stations. An accurate formula was obtained to determine the optimum number of SC deployment (NSC). Finally, we derive a mathematical expression to calculate the critical-handoff-point (CHP) for neighboring wireless stations.
A CELLULAR BONDING AND ADAPTIVE LOAD BALANCING BASED MULTI-SIM GATEWAY FOR MO...pijans
As it is well known, the QoS(quality of service) provided by mobile Internet access point devices is far from
the QoS level offered by the common ADSL modem-router due to several reasons: in fact, mobile Internet
access networks are not designed to support real-time data traffic because of several drawbacks
concerning the wireless medium such as resource sharing, traffic congestion, radio link coverage etc.,
which impact directly such parameters as delay, jitter, and packet loss rate that are strictly connected to
the quality of user experience. The main scope of the present paper is to introduce a dual USIM HSPA
gateway for ad hoc and sensors networks thanks to which it will be possible to guarantee a QoS suitable
for a series of network-centric application such as real-time communications and monitoring, video
surveillance, real-time sensor networks, telemedicine, vehicular and mobile sensor networks and so on. The
main idea is to exploit multiple radio access networks in order to enhance the available end-to-end
bandwidth and the perceived quality of experience. The scope has been reached by combining multiple
radio access with dynamic load balancing and the VPN (virtual private network) bond technique.
This is a presentation I did at the pre-Master studies at Ain shams University. It\'s about algorithms and techniques of call admission when a mobile node moves among cell in a wireless network.
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.
The peer-reviewed International Journal of Engineering Inventions (IJEI) is started with a mission to encourage contribution to research in Science and Technology. Encourage and motivate researchers in challenging areas of Sciences and Technology.
An approach to control inter cellular interference using load matrix in multi...eSAT Journals
Abstract
This paper deals with reduction of inter cellular interference in Multi-carrier communication systems. In the past, Load Matrix(LM) is proposed to allocate power to different users in a network based upon Signal to noise plus interference ratio (SNIR) so as to reduce inter cellular interference and is observed for single carrier systems. In Multi carrier systems the SNIR is affected distinctly in each carrier thus a single SNIR for power allocation is not optimal. In this paper, to obtain the optimization of power allocation in Multi-Carrier system, Load Matrix coding with bifurcated SNIR (LM-BFSNIR) is proposed. Using this approach it is observed that inter cellular interference is reduced better when compared to a single carrier system evaluated over a 3GPP-LTE standard.
Keywords−Power allocation, Inter cellular interference, Multi-Carrier mobile Communication system.
Improving The Performance Of Multiuser OFDM Wireless System With UWB ChannelIJTET Journal
The multi user OFDM system can be used to produce a highly flexible and effective communication
system. In the existing multi user OFDM system, resource allocation to each user is the major problem. Also the existing
multi user OFDM system uses frequency diversity technique that requires sparse bandwidth and multiple receivers
improving the complexity. In order to increase the system performance, the proposed system allows multiple user data to
be multiplexed together to form a single OFDM symbol where the resources are allocated equally to all users. The
proposed multiuser OFDM system achieves double the capacity and better performance in terms of Signal-to-Noise Ratio
and Bit Error Rate of a single user OFDM system and the UWB channel is used to securely transmit the data through the
channel. Also, the proposed system reduces the receiver complexity by using polarization diversity to receive the
multipath components for multiple users.
As a consequence of the proliferation of smart phones and tablets, data traffic is growing significantly, both on the radio access links and the backhaul infrastructure of mobile operators’ networks. And although LTE and LTE Advanced offer higher data traffic throughput than that of 3G, given to their wider allocated bandwidths, the combined capacities of even these networks is not sufficient to meet projected future capacity demands.
The conventional solution to increasing the capacity of LTE mobile networks includes splitting macro-cells and/or adding more sites. Both of these solutions require high CAPEX and OPEX, so mobile operators are seeking new and cost effective ways of increasing their network capacity. One solution is to deploy small-cell base stations (BSs) within their existing macro-cellular networks, an approach referred to as Heterogeneous Networks.
It is well known that a HetNet not only increases the network capacity, but also provides better coverage and enhances the user’s experience. These benefits are achieved by offloading data traffic dynamically from MCBSs to SCBSs using an algorithm based on several parameters such as the characteristics of the traffic, the required QoS and network
Advanced antenna techniques and high order sectorization with novel network t...ijwmn
Mobile operators commonly use macro cells with trad
itional wide beam antennas for wider coverage in th
e
cell, but future capacity demands cannot be achieve
d by using them only. It is required to achieve max
imum
practical capacity from macro cells by employing hi
gher order sectorization and by utilizing all possi
ble
antenna solutions including smart antennas. This pa
per presents enhanced tessellation for 6-sector sit
es
and proposes novel layout for 12-sector sites. The
main target of this paper is to compare the perform
ance
of conventional wide beam antenna, switched beam sm
art antenna, adaptive beam antenna and different
network layouts in terms of offering better receive
d signal quality and user throughput. Splitting mac
ro cell
into smaller micro or pico cells can improve the ca
pacity of network, but this paper highlights the
importance of higher order sectorization and advanc
e antenna techniques to attain high Signal to
Interference plus Noise Ratio (SINR), along with im
proved network capacity. Monte Carlo simulations a
t
system level were done for Dual Cell High Speed Dow
nlink Packet Access (DC-HSDPA) technology with
multiple (five) users per Transmission Time Interva
l (TTI) at different Intersite Distance (ISD). The
obtained results validate and estimate the gain of
using smart antennas and higher order sectorization
with
proposed network layout.
Handover for 5G Networks using Fuzzy Logic: A ReviewAI Publications
The future organization world will be inserted with various ages of remote advances, like 4G and 5G. Simultaneously, the advancement of new gadgets outfitted with different interfaces is filling quickly as of late. As a result, the upward handover convention is created to give pervasive availability in the heterogeneous remote climate. Handover might be a fundamental a piece of any remote Mobile Communication Network. It is a way of mobile communication and portable communication during which cellular broadcast is relocate from one base station to another without losing connection to the mobile communication. Handover is one problem on Wireless Network (WN) and to unravel this problem various sorts of HO methods utilized in network. Fuzzy logic, Machine Learning and Optimization are the handover solving methods that are studied during this paper. This paper is a review of the handoff techniques. Fuzzy logic is that the best technique to unravel the HO problem and it's further implemented in 4G/5G network.
Security in Mobile Ad Hoc Network became very important due to the nature of wireless communication
between the nodes and the rapid movement of node which make Mobile Ad hoc Network vulnerable to
Attackers. Jamming is a DoS attack’s special category used in wireless networks. The attacker disrespects
the medium access control (MAC) protocol and transmits on the shared channel; either periodically or
continuously to target all or some communication, respectively. Distributed coordination function (DCF)
and Point coordination function (PCF) are the two different media access control (MAC) mechanisms
which are specified by the IEEE 802.11standard. PCF can achieve higher throughput than DCF due to the
nature of contention-free, therefore, this paper investigate the impact of PCF when integrated into the
TORA – Based MANET and how it can improve the performance of the network. OPNET – Based
simulation scenarios were created and the simulation was run and the results were collected which
investigate that PCF provided a good functionality to improve deficiency caused by the Jammers this by
increasing the throughput and decreasing the delay which is affected by the Jammers. PCF was a good
improvement with different levels of Jammers’ transmission power.
Privacy-preservation for sensitive data has become a challenging issue in cloud computing.Threat modeling as a part of requirements engineering in secure software development provides a structured approach for identifying attacks and proposing countermeasures against the
exploitation of vulnerabilities in a system. This paper describes an extension of Cloud Privacy Threat Modeling (CPTM) methodology for privacy threat modeling in relation to processing sensitive data in cloud computing environments. It describes the modeling methodology that involved applying Method Engineering to specify characteristics of a cloud privacy threat modeling methodology, different steps in the proposed methodology and corresponding products. We believe that the extended methodology facilitates the application of a privacy preserving cloud software development approach from requirements engineering to design
MATLAB Simulink for single phase PWM inverter in an uninterrupted power supplyIJMER
Now a day’s Uninterrupted power supply is very necessary for industry, and domestic purpose.
This paper presents the design and implementation of UPS for using personal computer. Here solar
energy is used for charging the battery in sunny days and in absence of solar energy it will automatically
connect to main AC supply. Also MATLAB simulation work is done for PWM single phase inverter and
full bridge rectifier.. Here microcontroller is used for switching between solar plate and main AC supply
to Battery. By using this method we can save our electricity bill which is consumed in charging of battery
Single Phase to Three Phase Converter Devesh Gupta
single phase to three phase converter by using digital converter in which we firstly convert single phase AC input to DC by using Rectifier and then again convert this DC into Three Phase Ac by using 3-Phase Inverter
AC Induction motor (IM) are used as actuators in many industrial processes. Although IMs are reliable, they are subjected to some undesirable stresses, causing faults resulting in failure. Monitoring of an IM is a fast emerging technology for the detection of initial faults. It avoids unexpected failure of an industrial process. Monitoring techniques can be classified as the conventional and the digital techniques.
1.1 PROTECTION SCHEME OF INDUCTION MOTOR
Classical monitoring techniques for three-phase IMs are generally provided by some combination of mechanical and electrical monitoring equipment. Mechanical forms of motor sensing are also limited in ability to detect electrical faults, such as stator insulation failures. In addition, the mechanical parts of the equipment can cause problems in the course of operation and can reduce the life and efficiency of a system.
It is well known that IM monitoring has been studied by many researchers and reviewed in a number of works. Reviews about various stator faults and their causes, and detection techniques, latest trends, and diagnosis methods supported by the artificial intelligence, the microprocessor, the computer and other techniques in monitoring unbalanced voltage inter turn faults, stator winding temperature and microcontroller based digital protectors have been recently studied subjects. In these, while one or two variables were considered together to protect the IMs, the variables of the motor were not considered altogether. Measurements of the voltages, currents, temperatures, and speed were achieved and transferred to the computer for final protection decision.
A programmable integrated circuit (PIC) based protection system has been introduced using Microprocessors and the solutions of various faults of the phase currents, the phase voltages, the speed, and the winding temperatures of an IM occurring in operation have been achieved with the help of the microcontroller, but these electrical parameters have not been displayed on a screen.
Nowadays, the most widely used area of programmable logic controller (PLC) is the control circuits of industrial automation systems. The PLC systems are equipped with special I/O units appropriate for direct usage in industrial automation systems. The input components, such as the pressure, the level, and the temperature sensors, can be directly connected to the input. The driver components of the control circuit such as contactors and solenoid valves can directly be connected to the output.
Medium Access Control with Scheduled Group Contention for Massive M2M Devices csandit
In a dense Machine-to-Machine (M2M) network, a large number of stations contend to achieve
transmission opportunity and it creates a critical congestion problem. To solve this issue, a
group-based contention Medium Access Control (MAC) protocol is introduced. Stations are
divided into small numbers of groups and only one station in each group will contend as a
group leader to achieve the reserved time interval dedicated to a winner group. It can reduce
the contention overhead and lessen the congestion problem. In this paper, we propose
Scheduled Group Contention MAC (SGCMAC) protocol to enhance the group-based contention
MAC. The proposed SGCMAC protocol divides groups based on the traffic categories of
stations and schedules the contention groups to reduce the contention overhead. We also
propose an efficient resource management mechanism in the group grant time to prevent the
waste of time caused by idle stations. Simulations with IEEE 802.11ah parameters demonstrate
that our proposed SGCMAC has performance gains over other group-based contention MAC
protocols.
A Distributed Three-hop Routing Protocol to Increase the Capacity of Hybrid W...1crore projects
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A QoS Based MAC Protocol For Wireless Ad-hoc NetworkIJNSA Journal
Multimedia communication over wireless Ad-hoc networks has become the driving technology for many of the important applications, experiencing dramatic market growth and promising revolutionary experiences in personal communication, gaming, entertainment, military, security, environment monitoring, and more. The advances in wireless communications and growth of real-time applications have necessitated the development of wireless networks that can support high Quality of Service (QoS) and power control. A node in an ad hoc network is normally battery operated which poses a huge constraint on the power consumption of such a node. Hence, designing a power efficient MAC protocol for ad hoc wireless networks is a major challenge. In this paper, we propose a CDMA based power controlled medium access protocol for mobile and ad hoc network (MNA). The protocol conserves power and provides QoS guarantees for multimedia traffics. In that network one of the fundamental challenger in MANETs is how to increase the overall network throughputs well as reading the delay while maintaining how energy consumption for packet processing in communication. simulation results shows that the performance of the protocol with increase in traffic while QoS is better in terms of Energy consumption, throughput, & communication delay than existing protocol.
Broadcast Scheduling Protocols in Multi-Hop Mobile Ad hoc NetworksIJCNCJournal
When packets are sending in multi-hop mobile unintended networks numerous problems occur like flooding, rebroadcast, broadcast latency, power conservation and collision. If multiple transmission of packets simultaneously in MANETs that using the slot assignments approach, when additional channels are transmitting at the same time as the first slot allocations, interference may occur at the nodes. Because of the multi-hops data transfer, the network performance is hampered by the constrained bandwidth and therefore the self-initiated topological alterations. Therefore, a broadcast algorithm is important within the mobile ad hoc network for collision control and reliable communication. This paper proposes two new broadcasting protocols: modify SRBS and DSB algorithms. The planned algorithms outperform context of efficiency, reliability, traffic overload and reachability in highly mobile networks is an enhanced performance within the different environments. Evaluation of simulation results with other well-known exiting protocols as DFCN and PEGSP algorithms shows that the proposed protocol performance is best within the wireless network and channel bandwidths are well utilized within the network.
BROADCAST SCHEDULING PROTOCOLS IN MULTIHOP MOBILE AD HOC NETWORKSIJCNCJournal
When packets are sending in multi-hop mobile unintended networks numerous problems occur like
flooding, rebroadcast, broadcast latency, power conservation and collision. If multiple transmission of
packets simultaneously in MANETs that using the slot assignments approach, when additional channels are
transmitting at the same time as the first slot allocations, interference may occur at the nodes. Because of
the multi-hops data transfer, the network performance is hampered by the constrained bandwidth and
therefore the self-initiated topological alterations. Therefore, a broadcast algorithm is important within the
mobile ad hoc network for collision control and reliable communication. This paper proposes two new
broadcasting protocols: modify SRBS and DSB algorithms. The planned algorithms outperform context of
efficiency, reliability, traffic overload and reachability in highly mobile networks is an enhanced
performance within the different environments. Evaluation of simulation results with other well-known
exiting protocols as DFCN and PEGSP algorithms shows that the proposed protocol performance is best
within the wireless network and channel bandwidths are well utilized within the network.
A Survey of Various Routing and Channel Assignment Strategies for MR-MC WMNsijsrd.com
One fundamental problem of WMNs with a limited number of radio interfaces and orthogonal channels is that the performance degrades significantly as the network size grows. This results from increased interference between nodes and diminished spatial reuse over the network. A WMN node needs to share a common channel with each of its neighbours in the communication range, requiring it to set up a virtual link. Moreover, to reduce network interference, a node should minimize the number of neighbours that it shares a common channel with. The objective of a channel assignment strategy is to ensure efficient utilization of the available channels (e.g., by minimizing interference) while maximizing connectivity in the network. However, since these two requirements are conflicting with each other, the goal is to achieve a balance between these two. The major constraints which need to be satisfied by a channel assignment scheme include fixed number of channels in the network, limited number of radios in mesh nodes, common channel between two communicating nodes, and limited channel capacity. Also, a channel assignment scheme should take the amount of traffic load supported by each mesh node into consideration.
A Case Study on Ip Based Cdma Ran by Controlling RouterIJERA Editor
As communication plays an important role in day to day life, the effective and efficient data transmission is to be maintained. This paper mainly deals with implements a congestion control mechanism using Router control method for IP-RAN on CDMA cellular network. The Router control mechanism uses the features of CDMA networks using active Queue Management technique to reduce delay and to minimize the correlated losses. When utilizing these new personal tools and services to enrich our lives, while being mobile, we are using Mobile Multimedia applications. As new handsets, new technologies and new business models are introduced on the marketplace, new attractive multimedia services can and will be launched, fulfilling the demands. Because the number of multimedia services and even more so, the context in which the services are used is numerous, the following model is introduced in order to simplify and clarify how different services will evolve, enrich our lives and fulfill our desires.The proposed paper work is to be realized using Matlab platform.
International Journal of Computational Engineering Research(IJCER)ijceronline
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.
Analysis of Handoff techniques used for hybrid networks: cellular/WLAN IJORCS
Most real life networks are hybrid networks. A hybrid network combines the best features of two or more networks. In networking terminology, a hybrid network according to “Information Technology control and Audit” are reliable and versatile. They provide large numbers of connections and data transmission paths to users. These hybrid networks may be treated as network nodes for analysis purpose. The two radio access technologies (RATs) are considered with cellular/WLAN depending on whether it is voice/ data, video. For observing practical result, some setups are required in laboratory which includes interface from personal computer to mobile terminal and vice-versa. The network simulator (Ns-2) is used for analysis purpose. The results shows the parameters like energy good put, Bandwidth utilization, packet delivery ratio, energy good put and energy consumed are improved after using hybrid networks.
INTERFERENCE-AWARE CHANNEL ASSIGNMENT FOR MAXIMIZING THROUGHPUT IN WMN pijans
Wireless Mesh network (WMN) is dynamically self-organizing and self-configured, with the nodes in the
network automatically establishing an ad-hoc network and maintaining the mesh connectivity. The ability
to use multiple-radios and multiple channels can be cashed to increase aggregate throughput of wireless
mesh network. Thus the efficient use of available interfaces and channels without interference becomes
the key factor. In this paper we propose interference aware clustered based channel assignment schemes
which minimizes the interference and increases throughput. In our proposed scheme we have given
priority to minimize interference from nearby mesh nodes in interference range than maximizing channel
diversity. We simulated our proposed work using NS-3 and results show that our scheme improves
network performance than BFSCA and Distributed Greedy CA.
Now-a-days, Internet has become an important part of human’s life, a person
can shop, invest, and perform all the banking task online. Almost, all the organizations have
their own website, where customer can perform all the task like shopping, they only have to
provide their credit card details. Online banking and e-commerce organizations have been
experiencing the increase in credit card transaction and other modes of on-line transaction.
Due to this credit card fraud becomes a very popular issue for credit card industry, it causes
many financial losses for customer and also for the organization. Many techniques like
Decision Tree, Neural Networks, Genetic Algorithm based on modern techniques like
Artificial Intelligence, Machine Learning, and Fuzzy Logic have been already developed for
credit card fraud detection. In this paper, an evolutionary Simulated Annealing algorithm is
used to train the Neural Networks for Credit Card fraud detection in real-time scenario.
This paper shows how this technique can be used for credit card fraud detection and
present all the detailed experimental results found when using this technique on real world
financial data (data are taken from UCI repository) to show the effectiveness of this
technique. The algorithm used in this paper are likely beneficial for the organizations and
for individual users in terms of cost and time efficiency. Still there are many cases which are
misclassified i.e. A genuine customer is classified as fraud customer or vise-versa.
Wireless sensor networks (WSN) have been widely used in various applications.
In these networks nodes collect data from the attached sensors and send their data to a base
station. However, nodes in WSN have limited power supply in form of battery so the nodes
are expected to minimize energy consumption in order to maximize the lifetime of WSN. A
number of techniques have been proposed in the literature to reduce the energy
consumption significantly. In this paper, we propose a new clustering based technique
which is a modification of the popular LEACH algorithm. In this technique, first cluster
heads are elected using the improved LEACH algorithm as usual, and then a cluster of
nodes is formed based on the distance between node and cluster head. Finally, data from
node is transferred to cluster head. Cluster heads forward data, after applying aggregation,
to the cluster head that is closer to it than sink in forward direction or directly to the sink.
This reduction in distance travelled improves the performance over LEACH algorithm
significantly.
The next generation wireless networks comprises of mobile users moving
between heterogeneous networks, using terminals with multiple access interfaces and
services. The most important issue in such environment is ABC (Always Best Connected) i.e.
allowing the best connectivity to applications anywhere at any time. For always best
connectivity requirement various vertical handover strategies for decision making have
been proposed. This paper provides an overview of the most interesting and recent
strategies.
This paper presents the design and performance comparison of a two stage
operational amplifier topology using CMOS and BiCMOS technology. This conventional op
amp circuit was designed by using RF model of BSIM3V3 in 0.6 μm CMOS technology and
0.35 μm BiCMOS technology. Both the op amp circuits were designed and simulated,
analyzed and performance parameters are compared. The performance parameters such as
gain, phase margin, CMRR, PSRR, power consumption etc achieved are compared. Finally,
we conclude the suitability of CMOS technology over BiCMOS technology for low power
RF design.
In Cognitive Radio Networks (CRN), Cooperative Spectrum Sensing (CSS) is
used to improve performance of spectrum sensing techniques used for detection of licensed
(Primary) user’s signal. In CSS, the spectrum sensing information from multiple unlicensed
(Secondary) users are combined to take final decision about presence of primary signal. The
mixing techniques used to generate final decision about presence of PU’s signal are also
called as Fusion techniques / rules. The fusion techniques are further classified as data
fusion and decision fusion techniques. In data fusion technique all the secondary users
(SUs) share their raw information of spectrum detection like detected energy or other
statistical information, while in decision fusion technique all the SUs take their local
decisions and share the decision by sending ‘0’ or ‘1’ corresponding to absence and presence
of PU’s signal respectively. The rules used in decision fusion techniques are OR rule, AND
rule and K-out-of-N rule. The CSS is further classified as distributed CSS and centralized
CSS. In distributed CSS all the SUs share the spectrum detection information with each
other and by mixing the shared information; all the SUs take final decision individually. In
centralized CSS all the SUs send their detected information to a secondary base station /
central unit which combines the shared information and takes final decision. The secondary
base station shares the final decision with all the SUs in the CRN. This paper covers
overview of information fusion methods used for CSS and analysis of decision fusion rules
with simulation results.
ZigBee has been developed to support lower data rates and low power consuming
applications. This paper targets to analyze various parameters of ZigBee physical (PHY).
Performance of ZigBee PHY is evaluated on the basis of energy consumption in
transmitting and receiving mode and throughput. Effect of variation in network size is
studied on these performance attributes. Some modulation schemes are also compared and
the best modulation scheme is suggested with tradeoffs between different performance
metrics.
This paper gives a brief idea of the moving objects tracking and its application.
In sport it is challenging to track and detect motion of players in video frames. Task
represents optical flow analysis to do motion detection and particle filter to track players
and taking consideration of regions with movement of players in sports video. Optical flow
vector calculation gives motion of players in video frame. This paper presents improved
Luacs Kanade algorithm explained for optical flow computation for large displacement and
more accuracy in motion estimation.
A rapid progress is seen in the field of robotics both in educational and industrial
automation sectors. The Robotics education in particular is gaining technological advances
and providing more learning opportunities. In automotive sector, there is a necessity and
demand to automate daily human activities by robot. With such an advancement and
demand for robotics, the realization of a popular computer game will help students to learn
and acquire skills in the field of robotics. The computer game such as Pacman offers
challenges on both software and hardware fronts. In software, it provides challenges in
developing algorithms for a robot to escape from the pool of attacking robots and to develop
algorithms for multiple ghost robots to attack the Pacman. On the hardware front, it
provides a challenge to integrate various systems to realize the game. This project aims to
demonstrate the pacman game in real world as well as in simulation. For simulation
purpose Player/Stage is used to develop single-client and multi-client architectures. The
multi- client architecture in player/stage uses one global simulation proxy to which all the
robot models are connected. This reduces the overhead to manage multiple robots proxy.
The single-client architecture enables only two robot models to connect to the simulation
proxy. Multi-client approach offers flexibility to add sensors to each port which will be used
distinctly by the client attached to the respective robot. The robots are named as Pacman
and Ghosts, which try to escape and attack respectively. Use of Network Camera has been
done to detect the global positions of the robots and data is shared through inter-process
communication.
In Content-Based Image Retrieval (CBIR) systems, the visual contents of the
images in the database are took out and represented by multi-dimensional characteristic
vectors. A well known CBIR system that retrieves images by unsupervised method known
as cluster based image retrieval system. For enhancing the performance and retrieval rate
of CBIR system, we fuse the visual contents of an image. Recently, we developed two
cluster-based CBIR systems by fusing the scores of two visual contents of an image. In this
paper, we analyzed the performance of the two recommended CBIR systems at different
levels of precision using images of varying sizes and resolutions. We also compared the
performance of the recommended systems with that of the other two existing CBIR systems
namely UFM and CLUE. Experimentally, we find that the recommended systems
outperform the other two existing systems and one recommended system also comparatively
performed better in every resolution of image.
Information Systems and Networks are subjected to electronic attacks. When
network attacks hit, organizations are thrown into crisis mode. From the IT department to
call centers, to the board room and beyond, all are fraught with danger until the situation is
under control. Traditional methods which are used to overcome these threats (e.g. firewall,
antivirus software, password protection etc.) do not provide complete security to the system.
This encourages the researchers to develop an Intrusion Detection System which is capable
of detecting and responding to such events. This review paper presents a comprehensive
study of Genetic Algorithm (GA) based Intrusion Detection System (IDS). It provides a
brief overview of rule-based IDS, elaborates the implementation issues of Genetic Algorithm
and also presents a comparative analysis of existing studies.
Step by step operations by which we make a group of objects in which attributes
of all the objects are nearly similar, known as clustering. So, a cluster is a collection of
objects that acquire nearly same attribute values. The property of an object in a cluster is
similar to other objects in same cluster but different with objects of other clusters.
Clustering is used in wide range of applications like pattern recognition, image processing,
data analysis, machine learning etc. Nowadays, more attention has been put on categorical
data rather than numerical data. Where, the range of numerical attributes organizes in a
class like small, medium, high, and so on. There is wide range of algorithm that used to
make clusters of given categorical data. Our approach is to enhance the working on well-
known clustering algorithm k-modes to improve accuracy of algorithm. We proposed a new
approach named “High Accuracy Clustering Algorithm for Categorical datasets”.
Brain tumor is a malformed growth of cells within brain which may be
cancerous or non-cancerous. The term ‘malformed’ indicates the existence of tumor. The
tumor may be benign or malignant and it needs medical support for further classification.
Brain tumor must be detected, diagnosed and evaluated in earliest stage. The medical
problems become grave if tumor is detected at the later stage. Out of various technologies
available for diagnosis of brain tumor, MRI is the preferred technology which enables the
diagnosis and evaluation of brain tumor. The current work presents various clustering
techniques that are employed to detect brain tumor. The classification involves classification
of images into normal and malformed (if detected the tumor). The algorithm deals with
steps such as preprocessing, segmentation, feature extraction and classification of MR brain
images. Finally, the confirmatory step is specifying the tumor area by technique called
region of interest.
A Proxy signature scheme enables a proxy signer to sign a message on behalf of
the original signer. In this paper, we propose ECDLP based solution for chen et. al [1]
scheme. We describe efficient and secure Proxy multi signature scheme that satisfy all the
proxy requirements and require only elliptic curve multiplication and elliptic curve addition
which needs less computation overhead compared to modular exponentiations also our
scheme is withstand against original signer forgery and public key substitution attack.
Water marking has been proposed as a method to enhance data security. Text
water marking requires extreme care when embedding additional data within the images
because the additional information must not affect the image quality. Digital water marking
is a method through which we can authenticate images, videos and even texts. Add text
water mark and image water mark to your photos or animated image, protect your
copyright avoid unauthorized use. Water marking functions are not only authentication, but
also protection for such documents against malicious intentions to change such documents
or even claim the rights of such documents. Water marking scheme that hides water
marking in method, not affect the image quality. In this paper method of hiding a data using
LSB replacement technique is proposed.
Today among various medium of data transmission or storage our sensitive data
are not secured with a third-party, that we used to take help of. Cryptography plays an
important role in securing our data from malicious attack. This paper present a partial
image encryption based on bit-planes permutation using Peter De Jong chaotic map for
secure image transmission and storage. The proposed partial image encryption is a raw data
encryption method where bits of some bit-planes are shuffled among other bit-planes based
on chaotic maps proposed by Peter De Jong. By using the chaotic behavior of the Peter De
Jong map the position of all the bit-planes are permuted. The result of the several
experimental, correlation analysis and sensitivity test shows that the proposed image
encryption scheme provides an efficient and secure way for real-time image encryption and
decryption.
This paper presents a survey of Dependency Analysis of Service Oriented
Architecture (SOA) based systems. SOA presents newer aspects of dependency analysis due
to its different architectural style and programming paradigm. This paper surveys the
previous work taken on dependency analysis of service oriented systems. This study shows
the strengths and weaknesses of current approaches and tools available for dependency
analysis task in context of SOA. The main motivation of this work is to summarize the
recent approaches in this field of research, identify major issue and challenges in
dependency analysis of SOA based systems and motivate further research on this topic.
In this paper, proposed a novel implementation of a Soft-Core system using
micro-blaze processor with virtex-5 FPGA. Till now Hard-Core processors are used in
FPGA processor cores. Hard cores are a fixed gate-level IP functions within the FPGA
fabrics. Now the proposed processor is Soft-Core Processor, this is a microprocessor fully
described in software, usually in an HDL. This can be implemented by using EDK tool. In
this paper, developed a system which is having a micro-blaze processor is the combination
of both hardware & Software. By using this system, user can control and communicate all
the peripherals which are in the supported board by using Xilinx platform to develop an
embedded system. Implementing of Soft-Core process system with different peripherals like
UART interface, SPA flash interface, SRAM interface has to be designed using Xilinx
Embedded Development Kit (EDK) tools.
The article presents a simple algorithm to construct minimum spanning tree and
to find shortest path between pair of vertices in a graph. Our illustration includes the proof
of termination. The complexity analysis and simulation results have also been included.
Radio Frequency identification (RFID) technology has become emerging
technique for tracking and items identification. Depend upon the function; various RFID
technologies could be used. Drawback of passive RFID technology, associated to the range
of reading tags and assurance in difficult environmental condition, puts boundaries on
performance in the real life situation [1]. To improve the range of reading tags and
assurance, we consider implementing active backscattering tag technology. For making
mobiles of multiple radio standards in 4G network; the Software Defined Radio (SDR)
technology is used. Restrictions in Existing RFID technologies and SDR technology, can be
eliminated by the development and implementation of the Software Defined Radio (SDR)
active backscattering tag compatible with the EPC global UHF Class 1 Generation 2 (Gen2)
RFID standard. Such technology can be used for many of applications and services.
Vehicle technology has increased rapidly in recent years, particularly in relation
to braking system and sensing system. In parallel to the development of braking
technologies, sensors have been developed that are capable of detecting physical obstacles,
other vehicles or pedestrians around the vehicle. This development prevents accidents of
vehicles using Stereo Multi-Purpose cameras, Automated Emergency Braking Systems and
Ultrasonic Sensors. The stereo multi-purpose camera provides spatial intelligence of up to
50 metres in front of the vehicle and there is an environment recognition of 500 metres.
Cars can automatically brake due to obstacles or any hindrance when the sensor senses the
obstacles. The braking circuit function is to brake the car automatically after receiving
signal from the sensors. All cars are competent in applying brakes automatically to a
maximum extent of deceleration of 0.4g. Integrated safety systems are based on three
principles. They are: collision avoidance, collision mitigation braking systems and forward
collision warning.
This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
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.
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.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
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
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
The Art Pastor's Guide to Sabbath | Steve ThomasonSteve Thomason
What is the purpose of the Sabbath Law in the Torah. It is interesting to compare how the context of the law shifts from Exodus to Deuteronomy. Who gets to rest, and why?
How to Create Map Views in the Odoo 17 ERPCeline George
The map views are useful for providing a geographical representation of data. They allow users to visualize and analyze the data in a more intuitive manner.
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facilitate its services and features in telecommunication sector which supports for voice over internet
protocol, internet protocol TV, video conferencing, High definition video clarity and prime connection for
acquiring services such as cloud computing. IEEE 802.16m Wimax standard amended as an enhancement of
advanced techniques and services to support extended or better cell coverage area and higher system
capacity. In order to achieve higher performance gathered by subscribers at cell edges, the concept of [1]
mobile multi-hop relay (MMR) system has been defined. It specifies architecture for multi-hop transmission.
Basically in conventional single relay transmission network only fixed relays are used, those are dedicated
and static device. The relays stations work on decode and forward (DF) strategy. In this strategy, source
station sends its signal [2], [3] to air, relay station first receive it and apply the DF strategy to decode the
signal successfully and then regenerate the same received source signal to transmit through multi hops to the
destination.
Wimax cannot deliver 70 Mbps data rate over a distance of 31 Miles; it can operate at higher bit rate or over
a long coverage but both the factors are not possible simultaneously. Due to this type of operating
disadvantage i.e. at above distance of 31 Miles Wimax results in delivering very low data rate or maximum
packet loss. On the other hand by reducing the distance between base station and destination station below 1
Km allows a subscriber to operate at very high bit rate. This problem is faced at cell edges of Wimax
coverage area. For the solution of this problem either we have to compromise at cell coverage area or go with
another alternate i.e. cooperative relaying. A vivid range of prior literature on cooperative relaying exists in
multi-hoping communication network. However this review article differs from prior work by selecting the
relay stations randomly, there is no prior requirement of helpers before initiation of signal transmission.
Cooperative communications have been proposed to achieve high throughput at cell edges similar to that of
MIMO (Maximum input maximum output) system. It replaces the conventional direct communication
architecture or single hop communication system into multi-hop transmission model [4]. In below presented
figure 1, we presented direct communication architecture between base station and subscribers; mostly
subscribers are taken as mobile nodes. Wimax i.e. Worldwide Interoperability for Microwave Access system
is a standard technology of IEEE family. The IEEE 802.16 standard for broadband wireless internet service is
known as WIMAX. A working group of broadband wireless access developed and deployed the standard
(802.16) in 1999, used to provide wireless mobile internet service (which broadend the bandwidth usage)
across the cities and rural areas, facilitate its services and features in telecommunication sector which
supports for voice over internet protocol, internet protocol TV, video conferencing, High definition video
clarity and prime connection for acquiring services such as cloud computing. IEEE 802.16m Wimax standard
amended as an enhancement of advanced techniques and services to support extended or better cell coverage
area and higher system capacity. In order to achieve higher performance gathered by subscribers at cell
edges, the concept of [1] mobile multi-hop relay (MMR) system has been defined. It specifies architecture for
multi-hop transmission. Basically in conventional single relay transmission network only fixed relays are
used, those are dedicated and static device. The relays stations work on decode and forward (DF) strategy. In
this strategy, source station sends its signal [2], [3] to air, relay station first receive it and apply the DF
strategy to decode the signal successfully and then regenerate the same received source signal to transmit
through multi hops to the destination.
Wimax cannot deliver 70 Mbps data rate over a distance of 31 Miles; it can operate at higher bit rate or over
a long coverage but both the factors are not possible simultaneously. Due to this type of operating
disadvantage i.e. at above distance of 31 Miles Wimax results in delivering very low data rate or maximum
packet loss. On the other hand by reducing the distance between base station and destination station below 1
Km allows a subscriber to operate at very high bit rate. This problem is faced at cell edges of Wimax
coverage area. For the solution of this problem either we have to compromise at cell coverage area or go with
another alternate i.e. cooperative relaying.
A vivid range of prior literature on cooperative relaying exists in multi-hoping communication network.
However this review article differs from prior work by selecting the relay stations randomly, there is no prior
requirement of helpers before initiation of signal transmission. Cooperative communications have been
proposed to achieve high throughput at cell edges similar to that of MIMO (Maximum input maximum
output) system. It replaces the conventional direct communication architecture or single hop communication
system into multi-hop transmission model [4]. In below presented figure 1, we presented direct
communication architecture between base station and subscribers; mostly subscribers are taken as mobile
nodes. Some of the mobile nodes are located at cell edges, due to strong attenuation, natural sources trees,
and forests etc, interference created by other users in the ongoing communication and relatively low transmit
power; the direct communication between BS and MS is put down.
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Fig. 1 Direct Communication between BS and SSs in Wimax system in presence of natural sources
Most of the existing literature work on cooperative relaying network has adopted the half duplex protocol, in
which relay station transmit and receive the source signal in different time-slots. This orthogonality results in
inefficient use of channel bandwidth. Due to inefficient use of channel bandwidth the dispersion variation of
packet delay becomes unmanageable. On the other hand, full-duplex relaying [5], [6] overcomes the
drawbacks specified in the above half duplex scenario by allowing the relay stations to transmit and receive
in the same time-slot and [7] frequency band. This simultaneous process results in efficiently use of system
resources and channel bandwidth and outperforms the half duplex protocol. In this work, we study the effect
of selection and indexing scheme randomized- Distributed Space Time for mobility environment with respect
of half duplex and full duplex protocols. The full duplex (FD) protocol requires only one channel [8] for end-
to-end transmission, due to this; FD introduces loop back interference (to be described in section III in detail)
due to signal leakage between the relay station output and input. We study the feasibility of the full duplex
protocol in the presence of residual loop back interference, we consider a threshold point where FD mode can
outperforms the HD mode.
The rest of this article is organized as follows. Randomized Distributed Space Time scheme is introduced in
Section II with their Physical Layer and MAC layer specifications. In Section III, these models are applied to
check feasibility with FD protocol and analysis the problem loop back interference introduced due to FD
mode.
II. SPECIFICATION OF R-DSTC SCHEME
Wimax, A Metropolitan access network technology is much demanded in compacted and hardly populated
areas such as East Africa and North America. It has various advantages like supporting high data rates and
offering ultra-wideband. The enhanced standard IEEE 802.16j introduced mobile multi-hop relaying. A
Wimax conventional multi-hoping relay [1] network mainly consists of three network components as shown
in Fig. 2: the base station, subscriber stations and the relay stations, See Fig 2. Due to low transmit power and
other responsible factors, at cell edges any mobile node can communicate with the help of relative relay
station.
On the other hand, those subscriber’s nodes have strong transmit power capability, can communicate directly.
As presented in Fig 2. home subscriber 1 has enough power signals to communicate with base station
directly. Relay-assisted multi-hop communications have been shown to acquire significant [9] efficiency
boosters at cell edge’s problems over the legacy of direct communication between base station and
subscribers. In multi-hop relay networks, the advantage of multiple relays enhances the reliability and
throughput performance. Benefits of multi-hoping includes to overcome dead spots, reduction of transmit
power and increases the capacity gain. The term diversity technique is single most imperative [10] patron for
reliable wireless communication, since the channel acquiring for communication may suffer from effects of
fading, high attenuation due to addition of destructive multi-paths in the same communication media and due
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Fig. 2. Network elements specified in IEEE 802.16j standard
to interference produced by other users in the same communication channel. It is impractical to diagnose the
transmitted signal at destination unless some less affected copy of the transmitted signal is lended to the
receiver in case of strict attenuation. For reliable communication, it is mandatory to transmit multiple copies
of the signal but with short delay. The overall communication overhead for the above technique is not
desirable in the situation where number of subscribers is large. Another reliable technique has been
introduced i.e. Space Time Coding. It is a method which has been utilized to [4] elevate the reliability of data
transmission in wireless communication by using multiple transmits antennas. Source transmits multiple
redundant copies of a data stream in the air in a hope that at least some of them (redundant copies) may
survive the physical path. Recently, several amendments have been introduced for cooperation among relays
to provide spatial gains without utilizing multiple transmit antennas.
Recently, two new cooperation protocols [3], [4]; Decode-and-Forward and Amplify-and-forward have been
introduced to achieve the expected spatial gains without using multiple antennas, which was mandatory
checkpoint in space-time-coding method. The problem identified in multi-mobile relaying network is
selection and indexing of the relay nodes. For indexing and perfect selection of relay nodes, various solutions
are being proposed, one such effective solution specified in [1], named Distributed Space Time coding
(DSTC). It is a physical layer technique used to authorize the capabilities of relay station, so that they act as a
helper in a multi relaying wireless network. DSTC turn to use spatial diversity gain and achieves more than
expected range of end-to-end transmission, better throughput performance and less bit error rate. If we see
highlights, a Wimax system is typically designed and deployed in highly mobile environment, more than
80% of subscribers are mobile subscribers. This may lead to a substantial overhead in a mobile network to
identify the location of mobile subscribers where the channel statistics vary frequently. Due to this, DSTC
has various flaws over mobility environment such as before each transmission of signal all the relays which a
central node controller wants to [8] recruit are selected and indexed, so that they know who wants to
participate in cooperation and which signal stream will be transmitted by different antennas of relay station.
In distributed environment with mobility, this leads to extra signalling overhead for monitoring the location
of mobile subscriber to select and index relaying for them.
For mobility environment, the drawbacks identified in DSTC scheme can be directed by employing an
effective variation of DSTC called, Randomized-Distributed Space Time Coding, which expel the
requirement of space time codeword simulation and reduces the coordination between the source and the
relays. Main flaws specified in DSTC scheme respect to mobility environment has been addressed by R-
DSTC unique [1], [8], [11] operation and service. This emerged physical layer technique allows every
intermediate node, not only indexed helpers simulated and selected in previous (DSTC) scheme for each
subscriber individually, to potentially work as a relay station as long as it successfully decodes the source
signal and eager to participate in cooperation. This result leads to perform better utilization of system
resources (bandwidth usage etc) and maintain the factors to control the loss of packets. As much as mobile
subscribers change their location, there is no prior requirement for indexing relay helpers for their signal
transmission. In this emerged technique, any source mobile node immediately sends its signal to air; if the
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signal capacity is too poor for direct communication with base station then any relay node with relaying
capability (to be described in Section IV) can decode the signal reliably and then relay it to air after re-
encoding. Therefore, the intermediate helpers with relaying capability can be conveniently selected on
demand.
III. FEASIBILITY OF FULL DUPLEX RELAY HELPERS
Most of the existing research has been worked on cooperative communication by assuming half duplex
relaying, where relay nodes works [3] to support the source transmission by transmitting and receiving the
source data in orthogonal1
channels. Since delay variations increases time by time, this leads to inefficiently
utilization of the channel bandwidth and ineffective impact on throughput performance. On the other hand
full duplex relaying consider simultaneously transmission and reception of signal which uses same frequency
and time channel at the radio relay, which leads to result more efficiently utilization of the spectral
efficiency. The full duplex mode requires only one channel for the end-to-end transmission. The channel can
be divided either in frequency division mode or in time division mode. In frequency division mode, the
uplink [12] and downlink channels are located on separate frequencies.
Fig. 3. Frequency Division Duplexing model
Fig. 4. Effect of loop back interference at relay station
In the above drawn Fig 3. We presented a frequency division model. Base station sends a frame after each
periodic [13] time in 2.5 to 20ms. The whole frequency channel divided into different frequency slots, in
which uplink subframe and downlink subframe are sent through separate frequency sub channels. A fixed-
1
Orthogonality is a technique used to utilize one common channel completely either for transmission purpose or for
reception of signal. Thus there is no interference possible at destination. Because following node is busy in listening the
status of channel.
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duration frame is used for both uplink and downlink transmissions, which is transmitted after each 2.5 to
20ms.
The simultaneous transmission and reception of signal at relay nodes, introduces a problem called loop back
interference. In wireless communication, interference produced by other user’s communication, makes wrong
impact on system performance. The below mentioned problem is specified in [3], [5], [6], [14] in which
signal leakage occurs at relay station between the relay output and input. Basically, relay nodes receive
source data plus transmitting data which is transmitting by them (same relay nodes) and some additive white
Gaussian noise2
. See Fig 4. We have taken some [3], [15] abbreviations like ƴSR, ƴLI and ƴRD which
represents the channel gain factors with respective to frequency-flat-source-relay, residual loop interference
and relay-destination channels. As shown in the Fig 4. SS1 sends a signal to relay station using decode-and-
forward protocols, at the same time that same relay node sends a signal which is received from other SS2 and
simultaneously receives the signal from source station SS1. At relay station, both transmitting signal and
currently receiving signal are collapsed and relay station cannot determine the receiving signal. On the other
hand, the half-duplex mode eliminates the loop back interference, but this dwindles the end-to-end rate. In
full duplex mode, if we maintain the loop back interference value up to a controlled level by increasing the
distance and by placing the obstacles between the antennas, our model can outperforms the half duplex mode
easily. Now here a question arises, how much loop back interference level is acceptable? In order to analysis
the feasibility of full-duplex employed with a relay station in the presence of threshold point (controlled
level) of loop back interference. We focus on following issues- should loop back interference be permitted in
full duplex mode or full duplex mode can achieve the double performance that of achieved by half duplex
mode.
IV. RELAY RECRUITMENT AND MAC LAYER SPECIFICATION
The recruitment policy of relay nodes for R-DSTC scheme is different from DSTC scheme. Basically R-
DSTC scheme is used for distributed mobile environment, where channel statistics vary frequently. In DSTC
scheme, a predefined set of helpers are recruited before the initiation of signal [1] , [11] transmission, is
synchronized in a pattern that is being indexed for a specific antenna of a space time coding where each relay
node simulates a specific antenna of an underlying STC code.
Fig. 5A. Cooperative communication in mobility environment
Since a specific signal stream is transmitted by unique helper corresponding to its designated antenna, this
helper is recruited prior and indexed for transmission of this single signal stream until channel statistics does
not being changed. In conventional cooperative communication networks have only fixed relays for relaying
purpose. Let us assume we use DSTC scheme for cooperative relaying and selects and indexes some
2
Additive white Gaussian noise is random radio noise characterized by a wide frequency band. The additive property of
noise stands that received signal equals to the transmitted signal plus some noise, where additional noise has no relation
with signal.
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Fig. 5B. Cooperative communication in mobility environment
predefined helpers for a specific mobile subscriber. In the above presented Fig 5A, we consider cooperative
communication system in mobility mode. In Fig 5A. At time t1 a mobile subscriber is located at some
location inside the Wimax system coverage area. We assume at time t1, the distance between MS1 is
approximately 30 Miles and associated relay node is located in between MS1 and base station. Initially
distance between RS and MS 1 and between BS and RS are about 12 Miles and 20 Miles respectively. We
assume that using DSTC scheme before data transmission relay node 1 is associated with MS1 for
cooperative communication. But after time t2, MS1 is being moved to some other location, presented in Fig
5B. We can see that still relay node is associated with MS1 as a cooperative relaying. But now scenario has
been changed in terms of distance and power transmission. The distance between RS1 and MS1 (still located
at cell edge) is about 35 miles, which is impossible for relay station to reliably decode the source signal.
Faults which are addressed by above problems can be easily rectified by R-DSTC scheme. A large scale
Wimax system requires a huge number of relay stations for better performance of the model. In order to
provide high end-to-end transmission, we are taking three types of relaying nodes [1], [9] : RSs- standard
conventional fixed relay station, femto/picocell BSs- the fixed femto/picocell BSs with wireless relay
functionality, and mobile relays- any subscriber station with relaying capability, wishes to work as helper.
A. Relay Node Discovery
In IEEE 802.16j standard, some basic functionalities and services offered by conventional relay stations are
predestined and known by the base station. Other additional relay stations such as any subscriber and sub-
base stations are required to identify the functionalities and services by base station. Any additional relay
stations can likely work as a helper and required to endorse their services. When any station enters into the
network either it is fixed relay station or any additional subscriber, it instantly delivers a basic capability
request (SBC-REQ) message to the base station announcing their essential services it can support. In the
pattern of SBC-REQ message specified in [1] includes a bit to classify the cooperative capacity of the
additional subscribers are empowered or not. That message also contains various information such as number
of antennas available for relaying purpose, mobility model and exact location of the relay node. In reply of
SBC-REQ message base station acknowledged by sending subscriber basic capability response (SBC-RSP)
message. Based on this transmission, the base station explores the existence of all available helpers.
B. Selection of Relay Nodes
In order for selection and indexing the helpers/relay nodes for each subscriber station, the base station
performs recruitment strategy, if it requires. At cell edges, most of the subscribers communicate through
cooperative relaying. It is consider that the direct communication from the source to destination is stagnant
due to strong fading of signal and comparatively low transmit power. As specified by author in [1], [4], [12],
[15] base station periodically broadcasts the downlink channel descriptor (DCD) and uplink channel
descriptor (UCD) message in a Wimax system to all nodes. The DCD is type of medium access control
management message and it encompasses information regarding frame duration codes, downlink burst
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profiles and parameters required for transmission such as modulation and coding techniques. Basically
Wimax system has divided its MAC layer into three sub layers parts- convergence sub layer, common part
sub layer and security sub layer. The common part layer is mostly responsible for connection establishment,
resource allocation required for connection establishment and scheduling between base station and subscriber
stations. The SS establishes a connection with BS using the contention slots [12] in the uplink sub-frame. For
entering and registering a new SS into the network, subscriber must follow the following procedures-
I. Base Station periodically sends the Uplink/Downlink map messages and Uplink channel descriptor
& Downlink channel descriptor into the air.
II. When any new subscriber enters into the network, it receives the downlink map message. It tries to
establish physical synchronization with the base station.
III. In the second step, subscriber waits for the uplink channel descriptor message to obtain the required
parameters for uplink channel.
IV. After successfully obtaining the uplink channel parameters, subscriber again receives the
uplink/downlink map to extract the time slot information for uplink communication.
V. Performing above steps successfully, in the next periodic time slot 2.5- 20ms; subscriber wait for
transmission opportunity to perform ranging operation.
Initially, when any new SS enters into the network, it waits for Downlink/uplink –map message; which is
periodically sent by base station after a certain interval. As well as base station sends downlink channel
descriptor messages and uplink channel descriptor messages. After receiving the DCD successfully, SS
establishes the physical synchronization by retrieving the frequency offset information. Now SS knows
various information such as frame duration, downlink center, frequency and base station ID etc and waits for
uplink channel information. In the next step, SS retrieves parameters from UCD message that contain
information about uplink center frequency, bandwidth request opportunity size and most important is
cooperation control information element for our model. This information is required to index the relaying
helpers, which is embedded inside UCD message. After performing the ranging operation, a sixteen-bit
unique identification number is allotted within the network for each one BS to one SS that is referred to as
connection identifier (CID). Afterwards, allotted CID is used to establish the communication via relaying
helpers or all available nodes concert their transceivers to the signal transmitted through these CID’s and
relay it to the destination successfully.
V. CONCLUSIONS
In this article, we presented an effective cooperative model for Wimax system. Through literature review,
we identify that proposed model would outperform the previous model and check the feasibility of the model
in presence of loop back interference. We can use some physical obstacles between the transmission and
receiving antenna of the relay station to overcome the effects of loop back interference. We investigated that
our model would lead over distributed space time code model in a distributed environment with mobility.
There is a lot of scope for analysis and justify our assumption to calculate the performance measures in terms
of BER (bit error rate), throughput calculation that will help and positively support our assumption in favor.
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