Amplify and Forward (AF) relaying, which refers to simple amplification and forwarding of the information sent from a source to destination terminal. For the conventional three node Amplify and Forward (AF) relaying setup, investigate the effect of imperfect channel state information (CSI) at the relaying on the overall performance. In particular, consider variable gain AF relaying and derive expression for the outage and the error probability and expression for the complimentary cumulative distribution function (CCDF) of the peak-to-average power ratio (PAPR) at the relay is calculated. The proposed method was drawn from a performance analysis for outage CSI at the relay. Finally the project work was simulated using the MATLAB software.
Review of various adaptive modulation and coding techniques in wireless networkeSAT Journals
Abstract Adaptive modulation and coding (AMC) is a method which adapts its transmitting parameters according to the channel state and is used in various modern wireless communications to maximize spectrum efficiency by minimizing the error rate. One of the driving strengths of AMC is the Signal-to-Noise Ratio (SNR) estimation and feedback channel for adaptation. Degrading effects caused due to sudden variation in the channel over time sometimes require the transmission link to react appropriately so it can minimize the Bit Error Rate (BER). There are various adaptive methods to implement the same like variable rate, variable error probability, and variable coding or hybrid technique. This article focuses upon variable power technique and describes two to three different power techniques and tries to make a comparison between two of them i.e, channel inversion and water-filling. Keywords- Adaptive Modulation and Coding (AMC), Bit Error Rate (BER), channel inversion, water-filling
Review of various adaptive modulation and coding techniques in wireless networkeSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
PALBMRP: Power Aware Load Balancing Multipath Routing Protocol for MANETEswar Publications
A set of mobile hosts or nodes that form a dynamic topology which is ad hoc in nature is called MANET. There are several challenges while designing a routing protocol for MANET due to the limited energy, less processing capability, fewer resources and dynamic environmental changes. Most of the existing energy efficient protocols focuses on choosing a route or path through the nodes with maximum residual energy and distribute a network traffic blindly among generated paths. Network congestion caused due to traffic and node packet carrying capability based on its remaining energy are not considered which leads to increasing number of dead nodes and result in more energy depletion. Hence we have proposed a Power Aware Load Balancing Multipath Routing Protocol (PALBMRP) which selects an optimal energy efficient route based on multiple parameters i.e. residual energy, delay, congestion and hop count and perform load balancing by considering nodes minimal residual energy to transmit packets according to its capacity. The simulation shows the proposed protocol reduced overall energy consumption up to 9%, increased packet delivery ratio up to 12%, and reduced end to end delay up to 3%, compared to AOMDV and LBMMRE-AOMDV [1].
PACKET SIZE OPTIMIZATION FOR ENERGY EFFICIENCY IN MULTIPATH FADING FOR WIRELE...IJCNCJournal
Recently, Wireless Body Area Network (WBAN) has drawn vast interest to many researchers due to its potential in healthcare and medical fields. In this paper, we propose the energy efficiency model of Time Diversity communication in Rician and Rayleigh fading channels emphasizing the optimal packet size. The optimal packet size to maximize energy efficiency is investigated for on-body and in-body channels. Four modulation techniques are considered including the recently proposed 16-ary Quadrature Amplitude Position Modulation (QAPM). In addition, the closed-form expression of the energy efficiency model in multipath fading is derived. Here, three evaluation metrics including the energy efficiency, the normalized throughput and the average end-to-end delay are adopted and compared to the existing 1-hop and Cooperative communications as well as our previously proposed 2-hop communication. The results show that our proposed Time Diversity communication scheme outperforms the existing ones in deep fading channel except for the average end-to-end delay
Review of various adaptive modulation and coding techniques in wireless networkeSAT Journals
Abstract Adaptive modulation and coding (AMC) is a method which adapts its transmitting parameters according to the channel state and is used in various modern wireless communications to maximize spectrum efficiency by minimizing the error rate. One of the driving strengths of AMC is the Signal-to-Noise Ratio (SNR) estimation and feedback channel for adaptation. Degrading effects caused due to sudden variation in the channel over time sometimes require the transmission link to react appropriately so it can minimize the Bit Error Rate (BER). There are various adaptive methods to implement the same like variable rate, variable error probability, and variable coding or hybrid technique. This article focuses upon variable power technique and describes two to three different power techniques and tries to make a comparison between two of them i.e, channel inversion and water-filling. Keywords- Adaptive Modulation and Coding (AMC), Bit Error Rate (BER), channel inversion, water-filling
Review of various adaptive modulation and coding techniques in wireless networkeSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
PALBMRP: Power Aware Load Balancing Multipath Routing Protocol for MANETEswar Publications
A set of mobile hosts or nodes that form a dynamic topology which is ad hoc in nature is called MANET. There are several challenges while designing a routing protocol for MANET due to the limited energy, less processing capability, fewer resources and dynamic environmental changes. Most of the existing energy efficient protocols focuses on choosing a route or path through the nodes with maximum residual energy and distribute a network traffic blindly among generated paths. Network congestion caused due to traffic and node packet carrying capability based on its remaining energy are not considered which leads to increasing number of dead nodes and result in more energy depletion. Hence we have proposed a Power Aware Load Balancing Multipath Routing Protocol (PALBMRP) which selects an optimal energy efficient route based on multiple parameters i.e. residual energy, delay, congestion and hop count and perform load balancing by considering nodes minimal residual energy to transmit packets according to its capacity. The simulation shows the proposed protocol reduced overall energy consumption up to 9%, increased packet delivery ratio up to 12%, and reduced end to end delay up to 3%, compared to AOMDV and LBMMRE-AOMDV [1].
PACKET SIZE OPTIMIZATION FOR ENERGY EFFICIENCY IN MULTIPATH FADING FOR WIRELE...IJCNCJournal
Recently, Wireless Body Area Network (WBAN) has drawn vast interest to many researchers due to its potential in healthcare and medical fields. In this paper, we propose the energy efficiency model of Time Diversity communication in Rician and Rayleigh fading channels emphasizing the optimal packet size. The optimal packet size to maximize energy efficiency is investigated for on-body and in-body channels. Four modulation techniques are considered including the recently proposed 16-ary Quadrature Amplitude Position Modulation (QAPM). In addition, the closed-form expression of the energy efficiency model in multipath fading is derived. Here, three evaluation metrics including the energy efficiency, the normalized throughput and the average end-to-end delay are adopted and compared to the existing 1-hop and Cooperative communications as well as our previously proposed 2-hop communication. The results show that our proposed Time Diversity communication scheme outperforms the existing ones in deep fading channel except for the average end-to-end delay
Lclr filter design and modelling for harmonic mitigation in interconnected mi...eSAT Journals
Abstract Today many people are attracted towards distribution generation (DG) because of low energy cost power supply, local generation, highly reliable system, supply with good power quality. Increasing attention and investment in renewable energy that is DG energy sources give rise to rapid development of high penetration renewable energy sources like solar energy, wind energy, hydro energy. Out of this most important and best is the solar energy. There are multiple ways to interface PV arrays with the power grid, but in there is problem of power quality. Today’s important concern of the power system is the power quality in case of renewable energy sources. The power quality improvement in the interconnected micro grid systems and grid interconnection with Distribution Generation (DGs) is the challenging task and to overcome the power quality problem passive filters are the best and cost effective solution. In this paper the LCLR filter is implemented between inverter and grid. The complete system consists of photovoltaic cell (PV), DC-DC boost converter, DC-AC inverter, LCLR filter and the grid. This paper also consists of complete MATLAB simulation of PV cell, DC-DC boost converter and inverter with LCLR filter. Key Words: Renewable energy, PV module, DC-DC boost converter, DGs, LCLR filter, power quality, micro grid (MG) and THD
MPC-EAR : Maximal Power Conserved And Energy Aware Routing in Ad hoc Networksijsrd.com
Power preservation in wireless ad hoc networks is a decisive factor as energy resources are inadequate at the electronic devices in use. Power-aware routing strategies are fundamentally route selection strategies built on accessible ad hoc routing protocols. This paper proposed a new Maximal Power Conserved And Energy Aware Routing (MPC-EAR ) topology for mobile ad hoc networks that enhances the network life span. Simulation results prove that the projected protocol has a higher performance other minimal energy usage, energy level aware and energy conserving routing protocols such as MTPR, MMECR and CMMECR.
Kalman Filter Estimation of Impedance Parameters for Medium Transmission LineTELKOMNIKA JOURNAL
Accurate knowledge of impedance parameters in transmission line helps to improve the system efficiency and performance. Nowadays, the estimation of impedance parameters in transmission line has become possible with the availability of computational method. This paper aims to develop Kalman filter model by using Matlab simulink to estimate accurate values of resistance (R), reactance (X), and susceptance (B) in medium transmission line. The accuracy of the parameters can be improved by reducing the unknown errors in the system. To demonstrate the effectiveness of the Kalman filter method, a case study of simulated medium transmission line is presented and comparison between Kalman Filter (KF) and Linear Least Square (LLS) method is also considered to evaluate their performances.
Distributed Utility-Based Energy Efficient Cooperative Medium Access Control...IJMER
Cooperative communication, that utilizes near terminals to relay the overhearing
information to grasp the variability gains, choices a nice potential to strengthen the transmission
potency in wireless networks. to the subsume the hard medium access interactions evoked by relaying
and leverage the advantages of such cooperation, associate economical Cooperative Medium Access
management (CMAC) protocol is required. throughout this paper, we've got an inclination to tend to
propose a completely unique cross-layer Wide unfold Energy-adaptive Location-based CMAC
protocol, notably WEAL-CMAC, for Mobile Ad-hoc Networks (MANETs). the design objective of
WEAL-CMAC is to strengthen the performance of the MANETs in terms of network amount and
energy potency. a wise energy consumption model is used throughout this paper, that takes the energy
consumption on each transceiver instrumentation and transmit instrumentation into thought. A
distributed utility-based best relay different strategy is incorporated, that selects the most effective
relay supported location information and residual energy. moreover, with the aim of enhancing the
spacial apply, associate innovative network allocation vector setting is provided to the subsume the
variable transmission power of the beginning and relay terminals. we've got an inclination to tend to
point that the planned WEAL-CMAC considerably prolongs the network amount below varied
circumstances even for prime instrumentation energy consumption cases by comprehensive simulation
study
This paper deals with the design of filters and THD analysis of a low - frequency ac (20Hz) transmission system. The LFAC system is interfaced with the 50Hz main power grid with a cycloconverter. The wind power is collected in dc form,and is connected to the L FAC transmission line with a twelve pulse inverter. The waveforms at the sending end and receiving end of the transmission line are plotted.THD analysis of LFAC system is carried out. The circuit model of LFAC system is simulated in MATLAB/SIMULINK.
Congestion Prediction and Adaptive Rate Adjustment Technique for Wireless Sen...IJORCS
In general, nodes in Wireless Sensor Networks (WSNs) are equipped with limited battery and computation capabilities but the occurrence of congestion consumes more energy and computation power by retransmitting the data packets. Thus, congestion should be regulated to improve network performance. In this paper, we propose a congestion prediction and adaptive rate adjustment technique for Wireless Sensor Networks. This technique predicts congestion level using fuzzy logic system. Node degree, data arrival rate and queue length are taken as inputs to the fuzzy system and congestion level is obtained as an outcome. When the congestion level is amidst moderate and maximum ranges, adaptive rate adjustment technique is triggered. Our technique prevents congestion by controlling data sending rate and also avoids unsolicited packet losses. By simulation, we prove the proficiency our technique. It increases system throughput and network performance significantly.
Rsaodv a route stability based ad hoc on demand distance vector routing prot...ijwmn
High mobility of mobile nodes is one of the major reasons for link failures in mobile ad hoc network (MANET). The present paper aims at proposing modification of well known Ad hoc On demand Distance Vector (AODV) routing protocol for MANET seeking stable route for data transmission and incorporating link break avoidance scheme for such networks. The performance of the proposed routing protocol, named as Route Stability based Ad hoc On demand Distance Vector (RSAODV), is evaluated considering some major performance metrics which include average route life time, throughput, packet delivery fraction, normalized routing load and end–to-end delay. The study is based on simulation runs adopting CBR traffic pattern taking care of node failure scenarios. The performance of RAODV is compared with AODV routing protocol. The simulation runs exhibit significant increase in average route life time, packet delivery fraction and throughput for RSAODV, on the other hand, the normalized routing load and end–to-end delay are reduced for this routing protocol as compared to AODV routing protocol.
Duty Cycle Corrector Using Pulse Width ModulationVLSICS Design
In circuits, clocks usually play a very important role. Whenever data needs to be sampled, it is done with respect to clock signals. It uses the edges of the clock to sample the data. So, it becomes very much necessary to see to it that the clock signals are properly received specially in receiver circuits where data sampling is done, mainly in Double data rate(DDR) circuits. Due to effects such as jitter, skew, interference, device mismatches etc., duty cycle gets affected. We come up with duty cycle correctors that ensure 50% duty cycle of the clock signals. A duty cycle corrector (DCC) with analog feedback is proposed and simulated in 45nm process technology node. The duty cycle corrector operates for MHz frequency range covering the duty cycle from 35%-65%, with +/- 1.5% accuracy. The design is simple and the power consumption is 1.01mW.
International Journal of VLSI design & Communication Systems (VLSICS) VLSICS Design
In circuits, clocks usually play a very important role. Whenever data needs to be sampled, it is done with respect to clock signals. It uses the edges of the clock to sample the data. So, it becomes very much necessary to see to it that the clock signals are properly received specially in receiver circuits where data sampling is done, mainly in Double data rate(DDR) circuits. Due to effects such as jitter, skew, interference, device mismatches etc., duty cycle gets affected. We come up with duty cycle correctors that ensure 50% duty cycle of the clock signals. A duty cycle corrector (DCC) with analog feedback is proposed and simulated in 45nm process technology node. The duty cycle corrector operates for MHz frequency range covering the duty cycle from 35%-65%, with +/- 1.5% accuracy. The design is simple and the power consumption is 1.01mW.
Lclr filter design and modelling for harmonic mitigation in interconnected mi...eSAT Journals
Abstract Today many people are attracted towards distribution generation (DG) because of low energy cost power supply, local generation, highly reliable system, supply with good power quality. Increasing attention and investment in renewable energy that is DG energy sources give rise to rapid development of high penetration renewable energy sources like solar energy, wind energy, hydro energy. Out of this most important and best is the solar energy. There are multiple ways to interface PV arrays with the power grid, but in there is problem of power quality. Today’s important concern of the power system is the power quality in case of renewable energy sources. The power quality improvement in the interconnected micro grid systems and grid interconnection with Distribution Generation (DGs) is the challenging task and to overcome the power quality problem passive filters are the best and cost effective solution. In this paper the LCLR filter is implemented between inverter and grid. The complete system consists of photovoltaic cell (PV), DC-DC boost converter, DC-AC inverter, LCLR filter and the grid. This paper also consists of complete MATLAB simulation of PV cell, DC-DC boost converter and inverter with LCLR filter. Key Words: Renewable energy, PV module, DC-DC boost converter, DGs, LCLR filter, power quality, micro grid (MG) and THD
MPC-EAR : Maximal Power Conserved And Energy Aware Routing in Ad hoc Networksijsrd.com
Power preservation in wireless ad hoc networks is a decisive factor as energy resources are inadequate at the electronic devices in use. Power-aware routing strategies are fundamentally route selection strategies built on accessible ad hoc routing protocols. This paper proposed a new Maximal Power Conserved And Energy Aware Routing (MPC-EAR ) topology for mobile ad hoc networks that enhances the network life span. Simulation results prove that the projected protocol has a higher performance other minimal energy usage, energy level aware and energy conserving routing protocols such as MTPR, MMECR and CMMECR.
Kalman Filter Estimation of Impedance Parameters for Medium Transmission LineTELKOMNIKA JOURNAL
Accurate knowledge of impedance parameters in transmission line helps to improve the system efficiency and performance. Nowadays, the estimation of impedance parameters in transmission line has become possible with the availability of computational method. This paper aims to develop Kalman filter model by using Matlab simulink to estimate accurate values of resistance (R), reactance (X), and susceptance (B) in medium transmission line. The accuracy of the parameters can be improved by reducing the unknown errors in the system. To demonstrate the effectiveness of the Kalman filter method, a case study of simulated medium transmission line is presented and comparison between Kalman Filter (KF) and Linear Least Square (LLS) method is also considered to evaluate their performances.
Distributed Utility-Based Energy Efficient Cooperative Medium Access Control...IJMER
Cooperative communication, that utilizes near terminals to relay the overhearing
information to grasp the variability gains, choices a nice potential to strengthen the transmission
potency in wireless networks. to the subsume the hard medium access interactions evoked by relaying
and leverage the advantages of such cooperation, associate economical Cooperative Medium Access
management (CMAC) protocol is required. throughout this paper, we've got an inclination to tend to
propose a completely unique cross-layer Wide unfold Energy-adaptive Location-based CMAC
protocol, notably WEAL-CMAC, for Mobile Ad-hoc Networks (MANETs). the design objective of
WEAL-CMAC is to strengthen the performance of the MANETs in terms of network amount and
energy potency. a wise energy consumption model is used throughout this paper, that takes the energy
consumption on each transceiver instrumentation and transmit instrumentation into thought. A
distributed utility-based best relay different strategy is incorporated, that selects the most effective
relay supported location information and residual energy. moreover, with the aim of enhancing the
spacial apply, associate innovative network allocation vector setting is provided to the subsume the
variable transmission power of the beginning and relay terminals. we've got an inclination to tend to
point that the planned WEAL-CMAC considerably prolongs the network amount below varied
circumstances even for prime instrumentation energy consumption cases by comprehensive simulation
study
This paper deals with the design of filters and THD analysis of a low - frequency ac (20Hz) transmission system. The LFAC system is interfaced with the 50Hz main power grid with a cycloconverter. The wind power is collected in dc form,and is connected to the L FAC transmission line with a twelve pulse inverter. The waveforms at the sending end and receiving end of the transmission line are plotted.THD analysis of LFAC system is carried out. The circuit model of LFAC system is simulated in MATLAB/SIMULINK.
Congestion Prediction and Adaptive Rate Adjustment Technique for Wireless Sen...IJORCS
In general, nodes in Wireless Sensor Networks (WSNs) are equipped with limited battery and computation capabilities but the occurrence of congestion consumes more energy and computation power by retransmitting the data packets. Thus, congestion should be regulated to improve network performance. In this paper, we propose a congestion prediction and adaptive rate adjustment technique for Wireless Sensor Networks. This technique predicts congestion level using fuzzy logic system. Node degree, data arrival rate and queue length are taken as inputs to the fuzzy system and congestion level is obtained as an outcome. When the congestion level is amidst moderate and maximum ranges, adaptive rate adjustment technique is triggered. Our technique prevents congestion by controlling data sending rate and also avoids unsolicited packet losses. By simulation, we prove the proficiency our technique. It increases system throughput and network performance significantly.
Rsaodv a route stability based ad hoc on demand distance vector routing prot...ijwmn
High mobility of mobile nodes is one of the major reasons for link failures in mobile ad hoc network (MANET). The present paper aims at proposing modification of well known Ad hoc On demand Distance Vector (AODV) routing protocol for MANET seeking stable route for data transmission and incorporating link break avoidance scheme for such networks. The performance of the proposed routing protocol, named as Route Stability based Ad hoc On demand Distance Vector (RSAODV), is evaluated considering some major performance metrics which include average route life time, throughput, packet delivery fraction, normalized routing load and end–to-end delay. The study is based on simulation runs adopting CBR traffic pattern taking care of node failure scenarios. The performance of RAODV is compared with AODV routing protocol. The simulation runs exhibit significant increase in average route life time, packet delivery fraction and throughput for RSAODV, on the other hand, the normalized routing load and end–to-end delay are reduced for this routing protocol as compared to AODV routing protocol.
Duty Cycle Corrector Using Pulse Width ModulationVLSICS Design
In circuits, clocks usually play a very important role. Whenever data needs to be sampled, it is done with respect to clock signals. It uses the edges of the clock to sample the data. So, it becomes very much necessary to see to it that the clock signals are properly received specially in receiver circuits where data sampling is done, mainly in Double data rate(DDR) circuits. Due to effects such as jitter, skew, interference, device mismatches etc., duty cycle gets affected. We come up with duty cycle correctors that ensure 50% duty cycle of the clock signals. A duty cycle corrector (DCC) with analog feedback is proposed and simulated in 45nm process technology node. The duty cycle corrector operates for MHz frequency range covering the duty cycle from 35%-65%, with +/- 1.5% accuracy. The design is simple and the power consumption is 1.01mW.
International Journal of VLSI design & Communication Systems (VLSICS) VLSICS Design
In circuits, clocks usually play a very important role. Whenever data needs to be sampled, it is done with respect to clock signals. It uses the edges of the clock to sample the data. So, it becomes very much necessary to see to it that the clock signals are properly received specially in receiver circuits where data sampling is done, mainly in Double data rate(DDR) circuits. Due to effects such as jitter, skew, interference, device mismatches etc., duty cycle gets affected. We come up with duty cycle correctors that ensure 50% duty cycle of the clock signals. A duty cycle corrector (DCC) with analog feedback is proposed and simulated in 45nm process technology node. The duty cycle corrector operates for MHz frequency range covering the duty cycle from 35%-65%, with +/- 1.5% accuracy. The design is simple and the power consumption is 1.01mW.
DUTY CYCLE CORRECTOR USING PULSE WIDTH MODULATIONVLSICS Design
In circuits, clocks usually play a very important role. Whenever data needs to be sampled, it is done with
respect to clock signals. It uses the edges of the clock to sample the data. So, it becomes very much
necessary to see to it that the clock signals are properly received specially in receiver circuits where data
sampling is done, mainly in Double data rate(DDR) circuits. Due to effects such as jitter, skew,
interference, device mismatches etc., duty cycle gets affected. We come up with duty cycle correctors that
ensure 50% duty cycle of the clock signals. A duty cycle corrector (DCC) with analog feedback is proposed
and simulated in 45nm process technology node. The duty cycle corrector operates for MHz frequency
range covering the duty cycle from 35%-65%, with +/- 1.5% accuracy. The design is simple and the power
consumption is 1.01mW.
On the performance of energy harvesting AF partial relay selection with TAS a...IJECEIAES
Energy scarcity has been known to be one of the most noticeable challenges in wireless communication system. In this paper, the performance of an energy harvesting based partial relay selection (PRS) cooperative system with transmit antenna selection (TAS) and outdated channel state information (CSI) is investigated. The system dual-hops links are assumed to follow Rayleigh distribution and the relay selection is based on outdated CSI of the first link. To realize the benefit of multiple antenna, the amplified-andforward (AF) relay nodes then employs the TAS technique for signal transmission and signal reception is achieved at the destination through maximum ratio combining (MRC) scheme. Thus, the closed-form expression for the system equivalent end-to-end cumulative distribution function (CDF) is derived. Based on this, the analytical closed-form expressions for the outage probability, average bit error rate, and throughput for the delaylimited transmission mode are then obtained. The results illustrated that the energy harvesting time, relay distance, channel correlation coefficient, the number of relay transmit antennas and destination received antenna have significant effect on the system performance. Monte-carol simulation is employed to validate the accuracy of the derived expressions.
This report discusses the planning Associate in
nursing the implementation of an OFDM system
in several information module schemes like MQPSK,
M-QAM. First, a short introduction is
provided by explaining the background and the
specification of the project. Then the report deals
with the system model, every block of the OFDM
system is represented (IFFT, FFT, Cyclic prefix,
modulation / reception, Channel estimation, bit
error rate). System design is analyzed. The
transmission techniques, further because the
system parameters for transmission and reception
are explained well. Finally, the results are
provided.
A DAPTIVE S UPPLY V OLTAGE M ANAGEMENT F OR L OW P OWER L OGIC C IRCU...VLSICS Design
With the rise in demand of portable hand held devic
es and with the rise in application of wireless sen
sor
networks and RFID reduction of total power consumpt
ion has become a necessity. To save power we
operate the logic circuitry of our devices at sub-t
hreshold. In sub-threshold the drain current is
exponentially dependent on the threshold voltage he
nce the threshold variation causes profound variati
on
of I
ON
and I
OFF
the ratio of which affect the speed of a circuit d
rastically. So to mitigate this problem we
present a adaptive power management circuit which w
ill determine the minimum required supply voltage
to meet the timing requirement. Also to reduce the
power overhead and avoid bulky coil and EMI noise
we used the switch capacitor power regulator to reg
ulate and manage power instead of linear dropout
(LDO) and Inductor base switch mode power converter
Throughput Maximization of Cognitive Radio Multi Relay Network with Interfere...IJECEIAES
In this paper, an Orthogonal Frequency Division Multiplexing (OFDM) based cognitive multi relay network is investigated to maximize the transmission rate of the cognitive radio (CR) with enhanced fairness among CR users with interference to the primary users (PUs) being managed below a certain threshold level. In order to improve the transmission rate of the CR, optimization of the subcarrier pairing and power allocation is to be carried out simultaneously. Firstly joint optimization problem is formulated and Composite Genetic and Ordered Subcarrier Pairing (CGOSP) algorithm is proposed to solve the problem. The motivation behind merging genetic and OSP algorithm is to reduce the complexity of Genetic Algorithm (GA). Further, to have a fair allocation of resources among CR users, the Round Robin allocation method is adopted so as to allocate subcarrier pairs to relays efficiently. The degree of fairness of the system is calculated using Jain‟s Fairness Index (JFI). Simulation results demonstrate the significant improvement in transmission rate of the CR, low computational complexity and enhanced fairness.
Compact low power high slew-rate cmos buffer amplifier with power gating tech...VLSICS Design
A qualitative analysis of different parameters such as Phase noise, Slew rate and tranconductance by using
power gating reduction technique is presented. The circuit achieves the large driving capability by
employing simple comparators to sense the transients of the input to turn on the output stages, which are
statically off in the stable state. The effect of the different number of transistors and their topologies on the
phase noise and Slew rate is analyzed. Good agreement between qualitative and quantitative measurements
is observed. Scope of reducing of Noise and avoidance of Leakage due to various sources is discussed.
An operational amplifier with recycling folded cascode topology and adaptive ...VLSICS Design
This paper presents a highly adaptive operational amplifier with high gain, high bandwidth, high speed
and low power consumption. By adopting the recycling folded cascode topology along with an adaptivebiasing
circuit, this design achieves high performance in terms of gain-bandwidth product (GBW) and slew
rate (SR). This single stage op-amp has been designed in 0.18μm technology with a power supply of 1.8V
and a 5pF load. The simulation results show that the amplifier achieved a GBW of 335.5MHz, Unity Gain
Bandwidth of 247.1MHz and a slew rate of 92.8V/μs.
A 20 gbs injection locked clock and data recovery circuitVLSICS Design
This paper presents a 20 Gb/s injection-locked clock and data recovery (CDR) circuit for burst mode
applications. Utilizing a half rate injection-locked oscillator (ILO) in the proposed CDR circuit leads to
higher speed operation and lower power consumption. In addition, to accommodate process, voltage, and
temperature (PVT) variations and to increase the lock range, a frequency locked loop is proposed to use in
this circuit. The circuit is designed in 0.18 μm CMOS and the simulations for 27-1 pseudo random bit
sequence (PRBS) show that the circuit consumes 55.3 mW at 20 Gb/s, while the recovered clock rms jitter
is 1.1 ps
A 20 Gb/s INJECTION-LOCKED CLOCK AND DATA RECOVERY CIRCUITVLSICS Design
This paper presents a 20 Gb/s injection-locked clock and data recovery (CDR) circuit for burst mode applications. Utilizing a half rate injection-locked oscillator (ILO) in the proposed CDR circuit leads to higher speed operation and lower power consumption. In addition, to accommodate process, voltage, and temperature (PVT) variations and to increase the lock range, a frequency locked loop is proposed to use in this circuit. The circuit is designed in 0.18 µm CMOS and the simulations for 27-1 pseudo random bit sequence (PRBS) show that the circuit consumes 55.3 mW at 20 Gb/s, while the recovered clock rms jitter is 1.1 ps.
A REVIEW PAPER ON AIR QUALITY METER WITH WARNING SYSTEMMichael George
Safety plays a major role in today’s world and it is necessary that good safety systems are to be implemented in places of education and work. This work modifies the existing safety model installed in industries and this system also be used in homes and offices. The main objective of the work is designing microcontroller based toxic gas detecting and alerting system. The hazardous gases like LPG and Air quality index gases were sensed and displayed each and every second in the LCD display. If these gases exceed the normal level then an alarm is generated immediately and also an alert message (SMS) is sent to the authorized person through the GSM. The advantage of this automated detection and alerting system over the manual method is that it offers quick response time and accurate detection of an emergency and in turn leading faster diffusion of the critical situation
FINGERPRINT BASED LOCKER WITH IMAGE CAPTUREMichael George
As we are moving in a World of advancement, so the security is the major concern in order to keep data isolate from the unauthorised users to access. In today’s World, we need high degree security system for the protection of our document, important data, as well as memory and jewellery. This review paper presents a secure fingerprint locker which is feasible. This system is proved successful on all norms of security of lockers. There are other methods of verifying authentication through password, RFID but this method is most efficient and reliable. To provide perfect security to the lockers and to make the work easier, this project is taking help of two different technologies, i.e. Embedded System and Biometrics. Biometrics is basically the measurement and use of unique characteristics of living beings to make them distinguish from one another. And this is more reliable then passwords and tokens which can be lost or stolen by the humans. In this paper we are providing the work done on this technique.
In this paper, a new sliding mode controller is proposed as the indirect control method and compared to a simple direct control method in order to control a buck converter in photovoltaic applications. The solar arrays are dependent power sources with nonlinear voltage-current characteristics under different environmental conditions. From this point of view, the DC/DC converter is particularly suitable for the application of the sliding mode control in photovoltaic application, because of its controllable states. Solar tracking allows more energy to be produced because the solar array is able to remain aligned to the sun. This method has the advantage that it will guarantee the maximum output power possible by the array configuration. Problems and possible improvements will also be presented.
LINE CALL REDUCTION USING PROCESS IMPROVEMENT IN AN AUTOMOBILE COMPANY: A SIM...Michael George
The aim of this paper is to decrease the chances of inventory going below the set minimum by eliminating the factors causing shortages and delays. When inventory goes below set minimum it is then called as line call, where the customer (Set Part Supply Department) demands immediate supply of those product undergoing shortage. The aim is to reduce the number of line calls by eliminating root causes for line calls. The reasons for line calls will be identified using root cause analysis and after studying the causes, counter measures for each cause will be identified and implemented. Some of these measures involve in changing processes and adding new equipment to reduce overall work and some involve statistically finding the problem areas in the data set. After all the two counter measures were implemented, we were able to reduce 85% of overall line calls leading to a large saving to the plant in terms of equipment area and man power. Also with the implementation of this concept, work burden to employees is reduced, thus creating an enjoyable work place.
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Ultraviolet disinfection is an attractive tool for treating water and eliminating pathogens with safe and available technology especially in developing countries where waterborne diseases cause the death of thousands of people every year. Even though UV is an easy tool to perform disinfection, concerns over the potential of microorganism reactivation constitute an issue for its development. In order to avoid this phenomenon, estimating the right dose of UV irradiance, the number of viable microorganisms and the sufficient contact time are important parameters to consider when performing UV disinfection. For this purpose, it’s current to use mathematical modelling. This work aimed to study the modelling of the kinetic of water disinfection by UV irradiation. Two kinetic models (Chick-Watson and Hom) were tested as to ability to scale disinfection of Gram negative Escherichia coli and Gram positive Lactobacillus Helveticus by different ultraviolet (UV) light inactivation process: UV alone, UV and TiO2 as a photocatalyst and finally UV and ZnO as a photocatalyst. The two tested models (Chick-Watson and Hom) fitted the kinetic of disinfection of E. coli. However, it must be noticed that, the simple agreement between experimental data and model predictions does not necessarily prove that either of the models is mechanistically correct. For the disinfection of L. Helveticus, neither of the two models fitted the experimental plots. The divergence existing between experimental and modelling results proves only that the empirical models can’t be generalized to all deactivated microorganisms.
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The Five Star Hotels in India, since a decade has started paying special attention towards a better sleep experience for their guests. The Hotel bedding revolution is a global phenomenon today and the hotels in India are no exception to it. Most of the guests are unable to sleep in the guest rooms either because the beds are uncomfortable, they do not get the desired pillow type, or the rooms are not dark enough or quiet for a sound sleep. The hotels provide different types of mattresses ,pillows, a good night kit with eye mask, ear plugs, special aroma therapy oil, sleep inducing music ,sleep inducing snacks for their guests as a part of the turn down service.The findings of this research suggests that the Five Star Hotels in Pune are making conscious effort to provide comfortable bed along with sound sleep experience to their guests to sustain in today`s competitive market. The concept is at an early stage, where the resources are available but not fully utilised. The hotel needs to train their staff to create the “wow” effect for their guests to return to their hotels.
We welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. All submitted articles should report original, previously unpublished research results, experimental or theoretical, and will be peer- reviewed. Articles submitted to the journal should meet these criteria and must not be under consideration for publication elsewhere. Manuscripts should follow the style of the journal and are subject to both review and editing. We hope you find this journal informative and useful. Your comments will help us to improve the quality and content of the journal.
SINGLE PHASING, PHASE REVERSAL, OVERVOLTAGE, UNDER VOLTAGE AND OVERHEATING PR...Michael George
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ESTIMATING PAPER IN VARIABLE GAIN RELAYING ON IMPERFECT CSI
1. International Journal of Scientific Research and Management Studies (IJSRMS)
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ESTIMATING PAPER IN VARIABLE GAIN RELAYING ON
IMPERFECT CSI
P.Vinothkumar1
and T.G.Dhaarani2
1
Department of Electronics and communication Engineering, Nandha Engineering
College, Erode, Tamilnadu, India
2
Assistant Professor, Nandha Engineering College, Erode, Tamilnadu, India
ABSTRACT
Amplify and Forward (AF) relaying, which refers to simple amplification and forwarding of the information
sent from a source to destination terminal. For the conventional three node Amplify and Forward (AF) relaying
setup, investigate the effect of imperfect channel state information (CSI) at the relaying on the overall
performance. In particular, consider variable gain AF relaying and derive expression for the outage and the
error probability and expression for the complimentary cumulative distribution function (CCDF) of the peak-to-
average power ratio (PAPR) at the relay is calculated. The proposed method was drawn from a performance
analysis for outage CSI at the relay. Finally the project work was simulated using the MATLAB software.
KEYWORDS: Imperfect channel state estimation, outage and error probability, peak-to-average power ratio
(PAPR).
I. INTRODUCTION
Wireless relaying technology is included in the standards of future wireless networks, such as the
Long Term Evolution-Advanced (LTE-A) system [1], due to a number of advantages that it promises
in terms of system coverage and performance. Amplify and forward (AF) relaying [4], which refers to
simple amplification and forwarding of the information sent from a source terminal to a destination
terminal, is considered to be the simplest implementation of wireless relaying in practice, since no
other form of processing at the relay is required. Among the several variations of AF relaying, the
most common one is so-called variable-gain relaying (VGR), where the gain employed at the relay
compensates the fading of the source-relay link, aiming at maintaining a constant relay transmits
power. In order to do so, the relay has to monitor the source-relay channel, such that the amplification
gain can be adjusted according to the obtained channel state information (CSI). In this respect, the
majority of the works in the literature assume perfect CSI acquisition [2]. Of particular interest is the
work, where it was shown that the gain policy that compensates for the source-relay channel leads to
optimal performance of AF VGR, provided, however, that the CSI available at the relay is perfect.
The above assumption of perfect CSI at both the relay and destination. We ground our argument on
the fact that the channel estimation is typically realized by using pilot symbols transmitted
periodically by the source, where the pilot insertion period depends on the channel coherence time of
the end-to-end channel. The source-relay channel estimate at the relay is needed only to set its gain G.
In order to conserve energy and to reduce complexity, the relay may estimate the source-relay channel
infrequently, i.e., the channel estimation rate at the relay may be insufficient to capture some rapid
source-relay channel fluctuations. Thus, although the relay may actually estimate the channel
perfectly, these estimates may be outdated by the time they are used to amplify the incoming signal
samples, because the actual source-relay channel [3] may change rapidly between two successive
channel estimates.
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In addition, it is also possible that the relay acquires imperfect CSI in cases where the CSI of the
source-relay link is fed back to the relay from another terminal which could be, for instance, a central
unit with global CSI knowledge. In such case, the relay may obtain limited feedback CSI, which
suffers from quantization noise2. Consequently, in the above scenarios the relay’s gain G is set to a
value that does not perfectly compensate the source-relay channel. This imperfect CSI at the relay
does not necessarily affect the quality of channel estimation at the destination, as highly accurate
(perfect) channel estimates are necessary for ideal coherent demodulation, as well as some higher
layer functions, such as scheduling. Thus, the destination may update its CSI estimation more
frequently than the relay.
The level of CSI imperfection at the relay is quantified through the power correlation coefficient
between the actual and the estimated channel values, ρ. The performance metrics considered in this
work are the end-to-end outage probability (OP), the average bit error probability (ABEP), and the
complimentary cumulative distribution function (CCDF) of the Peak-to-average-power ratio (PAPR)
at the output of the relay. It is noted that, as far as we are aware, this is the first time that the latter
metric is used for the analysis of AF relaying schemes with imperfect CSI at the relay.
Motivation behind using this metric is that, contrary to VGR schemes [5] with perfect CSI, the relay
transmit power in VGR experiences fluctuations when the CSI used for calculation of the relay gain is
imperfect. The CCDF of the PAPR can be thus used to obtain the probability with which the power
amplifier at the relay operates in its non-linear region, therefore distorting the output signal.
In this project, the effects of outdated channel estimation on the outage performance of amplify-and-
forward (AF) relay selection [3.6], where only one out of the set of available relays is activated. In
particular, we derive closed-form expressions for the outage probability of two variations of AF relay
selection, namely best relay selection and partial relay selection, when the selection is based upon
outdated channel estimates .Numerical results manifest that the outage performance of both schemes
under consideration is highly dependent on the level of imperfection of the channel estimates. It is
further shown that it may be preferable, in terms of outage probability, not to include links in the relay
selection process that experience high maximum Doppler shifts.
II. ADDITIVE WHITE GAUSSIAN NOISE
In wireless communications, channel state information (CSI) refers to known channel properties of a
communication link. This information describes how a signal propagates from the transmitter to the
receiver and represents the combined effect of, for example, scattering, fading, and power decay with
distance. The CSI makes it possible to adapt transmissions to current channel conditions, which is
crucial for achieving reliable communication with high data rates in multi antenna systems.
CSI needs to be estimated at the receiver and usually quantized and fed back to the transmitter
(although reverse-link estimation is possible in TDD systems). Therefore, the transmitter and receiver
can have different CSI. The CSI at the transmitter and the CSI at the receiver are sometimes referred
to as CSIT and CSIR, respectively.
2.1. Different Kinds of CSI
There are basically two levels of CSI, namely instantaneous CSI and statistical CSI.
1. Instantaneous CSI (or short-term CSI) means that the current channel conditions are known, which
can be viewed as knowing the impulse response of a digital filter. This gives an opportunity to adapt
the transmitted signal to the impulse response and thereby optimize the received signal for spatial
multiplexing or to achieve low bit error rates.
2. Statistical CSI (or long-term CSI) means that a statistical characterization of the channel is known.
This description can include, for example, the type of fading distribution, the average channel gain,
the line-of-sight component, and the spatial correlation. As with instantaneous CSI, this information
can be used for transmission optimization.
The CSI acquisition is practically limited by how fast the channel conditions are changing. In fast
fading systems where channel conditions vary rapidly under the transmission of a single information
symbol, only statistical CSI is reasonable.
On the other hand, in slow fading systems instantaneous CSI can be estimated with reasonable
accuracy and used for transmission adaptation for some time before being outdated. In practical
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systems, the available CSI often lies in between these two levels; instantaneous CSI with some
estimation/quantization error is combined with statistical information.
2.2. Variable Gain Relaying
The variable-gain or voltage-controlled relay is an electronic amplifier that varies its gain depending
on a control voltage (often abbreviated CV).A crude example is a typical inverting op-amp
configuration with a light-dependent resistor (LDR) [8] in the feedback loop. The gain of the
amplifier then depends on the light falling on the LDR, which can be provided by an LED (an opto
coupler). The gain of the amplifier is then controllable by the current through the LED. This is similar
to the circuits used in optical audio compressors.
A voltage-gain amplifier can be realized by first creating a voltage-controlled relay (VGR), which is
used to set the amplifier gain. The VCR is one of the numerous interesting circuit elements that can be
produced by using a JFET (junction field-effect transistor) with simple biasing. VCRs manufactured
in this way can be obtained as discrete devices, e.g. VCR2N.
2.3. Gaussian Estimation Error
Gaussian Estimation theory is a branch of statistics and signal processing that deals with estimating
the values of parameters based on measured/empirical data that has a random component. The
parameters describe an underlying physical setting in such a way that their value affects the
distribution of the measured data. An estimator attempts to approximate the unknown parameters
using the measurements. For example, it is desired to estimate the proportion of a population of voters
who will vote for a particular candidate. That proportion is the parameter sought; the estimate is based
on a small random sample of voters.
In Gaussian estimation theory, two approaches are generally considered.
(1)The probabilistic approach (described in this particle) assumes that the measured data is random
with probability distribution dependent on the parameters of interest.
(2)The set-membership approach assumes that the measured data vector belongs to a set which
depends on the parameter vector.
2.4. Semi Blind FGR
The performance of the semi-blind amplify-and-forward (AF) relay channel [7], where the
intermediate relay node is selected depending on the instantaneous and partial channel knowledge, is
investigated. Using closed-form expressions for the cumulative distribution function of the end-to-end
signal-to-noise ratio (SNR), outage probability, SNR moments and average bit error rate are derived.
The performance analysis is concerning fixed gain relays apply to blind relays with arbitrary fixed
gain. The statistical CSI about the first hop and have a particular knowledge of the average fading
power Ω1 which changes slowly (relative to α1) and as such does not imply continuous monitoring
system of the channel (as it is the case in CSI-assisted relay).The relay gain in the semi-blind scenario
is chosen such as
G2= E [Є2/Є1 α1+N01].
2.5. APS FGR
The average power scaling is defined as the rate of energy flow averaged over one full period (recall
that f =1/T).
Pavg= E/ T= EF.
It is easy to calculate the power or energy of optical pulses if theright parameters are known.
Presented here are the relationships among some basic quantities often needed when working with
laser pulses and power or energy meters.
In the average power scaling FGR the relay gain are given as
G2= ER/ [ESE ( α2)+N0 ]
The relay transmits power leading E (PR) = ER, i.e., the relay’s average transmit power equals ER.
2.6. Amplify and Forward
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The Nakagami distribution [9] or the Nakagami-m distribution is a probability distribution related to
the gamma distribution. It has two parameters: a shape parameter m and a second parameter
controlling spread, Ω.
The parameters m and Ω are
m= E2 [X2]/Var[X2],
Ω = E[X2].
An alternative way of fitting the distribution is to re-parametrize Ω and m as σ = Ω/m and m. Then, by
taking the derivative of log likelihood with respect to each of the new parameters, the following
equations are obtained and these can be solved using the Newton-Raphson method:
ᴦ (m) = x2m/σm,
σ = x2/m
It is reported by authors that modeling data with Nakagami distribution and estimating parameters by
above mention method results in better performance for low data regime compared to moments based
methods.
It describes the amplitude of received signal after maximum ratio diversity combining. After k-branch
maximum ratio combining (MRC) with Rayleigh-fading signals, the resulting signal is Nakagami with
m = k. MRC combining of m-Nakagami fading signals in k branches gives a Nakagami signal with
shape factor mk..
The sum of multiple independent and identically distributed. Rayleigh-fading signals have Nakagami
distributed signal amplitude. This is particularly relevant to model interference from multiple sources
in a cellular system.
The average time delay is assumed to differ significantly between clusters. If the delay times also
significantly exceed the bit time of a digital link, the different clusters produce serious intersymbol
interference, so the multipath self interference then approximates the case of co-channel interference
by multiple incoherent Rayleigh-fading signals. The Rician and the Nakagami model behave
approximately equivalently near their mean value. This observation has been used in many recent
papers to advocate the Nakagami model as an approximation for situations where a Rician model
would be more appropriate. While this may be accurate for the main body of the probability density, it
becomes highly inaccurate for the tails.
As bit errors or outages mainly occur during deep fades, these performance measures are mainly
determined by the tail of the probability density function (for probability to receive a low power). The
amplifying and forward (AF) relaying, the amplify-and-forward relay protocol is a protocol defined
for wireless cooperative communications. An example of a wireless communication network in which
cooperation improves the performance of the system is the relay network.
Figure 1 shows the AF relay functions with signal notations. The AF relay function is an amplification
of the received signal,
FAF (ySR) = βySR
Figure 1. Relay network with signal notations.
With β the relay transmit average power constraint coefficient. The coefficient β ensures that the
average transmits power at the relay is constant and equal to PR, therefore β is derived in a similar
way to the one obtained by Laneman:
E [|f (ySR) |2] ≤ PR
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E [|βySR|2] ≤ PR.
The probability of error may be considered as being the probability of making a wrong decision and
which would have a different value for each type of error. Secondly, it arises in the context of
statistical modeling (for example regression) where the model's predicted value may be in error
regarding the observed outcome and where the term probability of error may refer to the probabilities
of various amounts of error occurring.
The probability of the detector making an incorrect decision is called probability of error. Using the
Euclidean distance d, the Probability of error can be calculated as (for white noise)
Pbe =1/2 erfc (d2/4N0)
Probability of Symbol error
Pse = lPbe
Where l is the number of adjacent signal points with respect to any one signal Point.
The peak-to-average power ratio (PAPR) is a related measure that is defined as the peak amplitude
squared (giving the peak power) divided by the RMS value squared (giving the average power).
PAPR = |x|peak2/xrms2 = C2
2.6.1. Peak-To-Average Power Ratio
A peak-to-average power ratio meter (Par meter) is a device used to measure the ratio of the peak
power level to the time-averaged power level in an electrical circuit. This quantity is known as the
peak-to-average ratio (P/A r or PAR). Such meters are used as a quick means to identify degraded
telephone channels. Gaussian noise is statistical noise that has its probability density function equal to
that of the normal distribution, which is also known as the Gaussian distribution. In other words, the
values that the noise can take on are Gaussian-distributed. A special case is white Gaussian noise, in
which the values at any pair of times are identically distributed and statistically independent (and
hence uncorrelated). In applications, Gaussian noise is most commonly used as additive white noise to
yield additive white Gaussian noise.
Noise by definition is just unwanted sound. However, there is one special type of noise that has broad
application in the hearing sciences. This is gaussian noise. We will discuss some reasons for its
popularity in class. Gaussian noise is noise that has a random and normal distribution of instantaneous
amplitudes over time.
Figure 2 below shows a sample of gaussian noise with the normal (bell) curve drawn to the right to
represent the distribution of instantaneous amplitudes.
Figure 2. Gaussian noise sample with normal bell
Relays that receive and retransmit the signals between base stations and mobiles can be used to
increase throughput extend coverage of cellular networks. Infrastructure relays do not need wired
connection to network thereby offering savings in operators’ backhaul costs. Mobile relays can be
used to build local area networks between mobile users under the umbrella of the wide area cellular
networks.
Amplify-and-forward (AF) relays retransmit the signal without decoding while decode–and-forward
(DF) relays decode the received signal, encode the signal again, and transmit. Furthermore, relays can
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operate in half-duplex mode, i.e. they do not transmit and receive simultaneously in the same band, or
in full-duplex mode. The latter operation requires a spatial separation between transmit and receive
antennas to reduce loop-back interference from the transmit antennas to the receive antennas.
From signal processing point of view AF relays offer interesting challenges, especially when the AF
relay operates in full-duplex mode: Adaptive algorithms are required for loop-back interference
cancellation [10]. Furthermore, the effect of interference must be incorporated into analytical
performance studies. Spectral shaping of the transmitted signal requires advanced techniques for
digital filter design. The research benchmarks AF relays with DF relays taking into account the
aforementioned issues. We cooperate with High-frequency and microwave engineering group to gain
understanding of the actual propagation environment and loop-back interference with full-duplex
relays.
2.7. Result
Finally, a comparison between VGR with outdated CSI and FGR, in terms of the CCDF of the PAPR,
is shown in figure3. Similarly to the comparison in terms of the ABEP, we notice that there exists a
correlation coefficient threshold, ρ0, such that for ρ < ρ0 the CCDF of the PAPR is higher for VGR
than for FGR.
Figure 3. Output of PAPR
The higher ( ε) value of interest (equivalently, the larger the linear region of the power amplifier at the
relay), the higher ρ0. Therefore, Figure 3 shows sheds some light on the required reliability of the CSI
at the relay such that VGR is preferable over FGR. When we increased SNR (signal to noise ratio) by
using quantization, the overall performance of variable gain relaying can be improved. Figure 4 and
figure 5 shows variable gain relaying communication and increased SNR.
Figure 4. Variable Gain Relaying Communication
When we increased SNR (signal to noise ratio) by using quantization, the overall performance of
variable gain relaying can be improved.
7. International Journal of Scientific Research and Management Studies (IJSRMS)
Volume 1 Issue 1, pg: 26-32
http://www.ijsrms.com All Rights Reserved pg. 32
Figure 5. Increased SNR
III. CONCLUSIONS
When the gain used for channel compensation in AF variable gain relaying is based on imperfect CSI,
the overall performance is considerably impaired. The performance degradation is the larger the lower
the correlation between the actual and the estimated source relay channel, yet such performance
degradation does not affect the slope of the outage and error probability curves. This conclusion was
drawn from a performance analysis for outdated CSI at the relay. Nevertheless, it was shown that the
same analysis can also accommodate the case of Gaussian CSI errors at the relay. It was further
observed that, depending on the maximum Doppler frequency, variable gain relaying requires
frequent updates of the source-relay channel in order to outperform its less complex counterpart, that
is, fixed gain relaying. Our investigation also included an analysis of the peak-to-average power ratio
for variable and fixed gain relaying, revealing that the probability of exceeding the amplifier’s linear
region (and thus causing signal distortion) can be higher for variable gain relaying, if the CSI at the
relay is not reliable enough.
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