This contribution introduces a new transmission scheme for multiple-input multiple-output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) systems. The new scheme is efficient and suitable especially for symmetric channels such as the link between two base stations or between two antennas on radio beam transmission. This survey Paper presents the performance analysis of V-BLAST based multiple inputs multiple output orthogonal frequency division multiplexing (MIMO-OFDM) system with respect to bit error rate per signal to noise ratio (BER/SNR) for various detection techniques. A 2X2 MIMO-OFDM system is used for the performance evaluation. The simulation results shows that the performance of V-BLAST based detection techniques is much better than the conventional methods. Alamouti Space Time Block Code (STBC) scheme is used with orthogonal designs over multiple antennas which showed simulated results are identical to expected theoretical results. With this technique both Bit Error Rate (BER) and maximum diversity gain are achieved by increasing number of antennas on either side. This scheme is efficient in all the applications where system capacity is limited by multipath fading.
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.
The innovative and effective use of information and communication technologies (ICT) is becoming increasingly important to improve the economy of the world [1]. Wireless communication networks are perhaps the most critical element in the global ICT strategy, underpinning many other industries. It is one of the fastest growing and most dynamic sectors in the world.
The European Mobile Observatory (EMO) reported that the mobile communication sector had total revenue of €174 billion in 2010, there- by bypassing the aerospace and pharmaceutical sectors [2]. The development of wireless technologies has greatly improved people’s ability to communicate and live in both business operations and social functions.
The phenomenal success of wireless mobile communications is mirrored by a rapid pace of technology innovation. From the second generation (2G) mobile communication system debuted in 1991 to the 3G system first launched in 2001, the wireless mobile network has transformed from a pure telephony system to a network that can transport rich multimedia contents. The 4G wireless systems were designed to fulfill the requirements of International Mobile Telecommunications-Advanced (IMT-A) using IP for all services [3]. In 4G systems, an advanced radio interface is used with orthogonal frequency-division multiplexing (OFDM), multiple-input multiple-output (MIMO), and link adaptation technologies. 4G wireless networks can support data rates of up to 1 Gb/s for low mobility, such as nomadic/local wireless access, and up to 100 Mb/s for high mobility, such as mobile access. Long-Term Evolution (LTE) and its extension, LTE-Advanced systems, as practical 4G systems, have recently been deployed or soon will be deployed around the globe.
However, there is still a dramatic increase in the number of users who subscribe to mobile broadband systems every year. More and more people crave faster Internet access on the move, trendier mobiles, and, in general, instant com- munication with others or access to information. More powerful smart phones and laptops are becoming more popular nowadays, demanding advanced multimedia capabilities. This has resulted in an explosion of wireless mobile devices and services. The EMO pointed out that there has been a 92 percent growth in mobile broadband per year since 2006 [2]. It has been predicted by the Wireless World Research Forum (WWRF) that 7 trillion wireless devices will serve 7 billion people by 2017; that is, the number of network-connected wireless devices will reach 1000 times the world’s population [4]. As more and more devices go wireless, many research challenges need to be addressed.
Design and analysis of mimo system for uwb communicationijwmn
Multiple transmit and receive antennas are used MIMO system. The system creates parallel MIMO
subchannels to transmit independent streams of data under the appropriate channel conditions. Similarly,
Ultrawideband (UWB) communication has attracted great interest for various applications in recent days.
Spatially multiplexed (SM) multiple-input multiple-output (MIMO) systems gains the spectral efficiency as
well as high data rates without consuming additional power, bandwidth or time slots. In this paper, we
extend the concept of MIMO to UWB systems. The correlated channel for such purpose is considered and
the performance has been analyzed for spatial multiplexing SM-UWB-MIMO system which is required for
estimation. The system performance substantially degrades in the presence of high values of spatial
correlation. To avoid the degradation of such system, it has been designed for virtual UWB-MIMO Time
Reversal (TR) system, so that it is not affected by the transmit correlation. Another novel method to reduce
the effect of correlation has been chosen by taking the Eigen value of the channel matrix for the
computation of the system performance. The result shows its performance.
A Potent MIMO–OFDM System Designed for Optimum BER and its Performance Anal...inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
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.
The innovative and effective use of information and communication technologies (ICT) is becoming increasingly important to improve the economy of the world [1]. Wireless communication networks are perhaps the most critical element in the global ICT strategy, underpinning many other industries. It is one of the fastest growing and most dynamic sectors in the world.
The European Mobile Observatory (EMO) reported that the mobile communication sector had total revenue of €174 billion in 2010, there- by bypassing the aerospace and pharmaceutical sectors [2]. The development of wireless technologies has greatly improved people’s ability to communicate and live in both business operations and social functions.
The phenomenal success of wireless mobile communications is mirrored by a rapid pace of technology innovation. From the second generation (2G) mobile communication system debuted in 1991 to the 3G system first launched in 2001, the wireless mobile network has transformed from a pure telephony system to a network that can transport rich multimedia contents. The 4G wireless systems were designed to fulfill the requirements of International Mobile Telecommunications-Advanced (IMT-A) using IP for all services [3]. In 4G systems, an advanced radio interface is used with orthogonal frequency-division multiplexing (OFDM), multiple-input multiple-output (MIMO), and link adaptation technologies. 4G wireless networks can support data rates of up to 1 Gb/s for low mobility, such as nomadic/local wireless access, and up to 100 Mb/s for high mobility, such as mobile access. Long-Term Evolution (LTE) and its extension, LTE-Advanced systems, as practical 4G systems, have recently been deployed or soon will be deployed around the globe.
However, there is still a dramatic increase in the number of users who subscribe to mobile broadband systems every year. More and more people crave faster Internet access on the move, trendier mobiles, and, in general, instant com- munication with others or access to information. More powerful smart phones and laptops are becoming more popular nowadays, demanding advanced multimedia capabilities. This has resulted in an explosion of wireless mobile devices and services. The EMO pointed out that there has been a 92 percent growth in mobile broadband per year since 2006 [2]. It has been predicted by the Wireless World Research Forum (WWRF) that 7 trillion wireless devices will serve 7 billion people by 2017; that is, the number of network-connected wireless devices will reach 1000 times the world’s population [4]. As more and more devices go wireless, many research challenges need to be addressed.
Design and analysis of mimo system for uwb communicationijwmn
Multiple transmit and receive antennas are used MIMO system. The system creates parallel MIMO
subchannels to transmit independent streams of data under the appropriate channel conditions. Similarly,
Ultrawideband (UWB) communication has attracted great interest for various applications in recent days.
Spatially multiplexed (SM) multiple-input multiple-output (MIMO) systems gains the spectral efficiency as
well as high data rates without consuming additional power, bandwidth or time slots. In this paper, we
extend the concept of MIMO to UWB systems. The correlated channel for such purpose is considered and
the performance has been analyzed for spatial multiplexing SM-UWB-MIMO system which is required for
estimation. The system performance substantially degrades in the presence of high values of spatial
correlation. To avoid the degradation of such system, it has been designed for virtual UWB-MIMO Time
Reversal (TR) system, so that it is not affected by the transmit correlation. Another novel method to reduce
the effect of correlation has been chosen by taking the Eigen value of the channel matrix for the
computation of the system performance. The result shows its performance.
A Potent MIMO–OFDM System Designed for Optimum BER and its Performance Anal...inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Multicarrier modulation can be implemented by using Orthogonal Frequency Division Multiplexing (OFDM) to achieve utmost bandwidth exploitation and soaring alleviation attributes profile besides multipath fading. To support delay sensitive and band bandwidth demanding multimedia applications and internet services, MIMO in addition with other techniques can be used to achieve high capacity and reliability. To obtain high spatial rate by transmitting data on several antennas by using MIMO with OFDM results in reducing error recovery features and the equalization complexities arise by sending data on varying frequency levels. Three parameters frequency OFDM, Spatial (MIMO) and time (STC) can be used to achieve diversity in MIMO-OFDM. This technique is dynamic and well-known for services of wireless broadband access. MIMO if used with OFDM is highly beneficial for each scheme and provides high throughput. There are several space time block codes to exploit MIMO OFDM; one of the techniques is called Alamouti Codes. The paper investigates adaptive Alamouti Codes and their application in IEEE 802.11n.
Ber analysis of 2x2 mimo spatial multiplexing under awgn and rician channels ...ijwmn
Multiple-input–multiple-output (MIMO) wireless systems use multiple antennas at transmitting and
receiving end to offer improved capacity and data rate over single antenna systems in multipath channels.
In this paper we have investigated the Spatial Multiplexing technique of MIMO systems. Here different
fading channels like AWGN and Rician are used for analysis purpose. Moreover we analyzed the technique
using high level modulations (i.e. M-PSK for different values of M). Detection algorithms used are Zero-
Forcing and Minimum mean square estimator. Performance is analyzed in terms of BER (bit error rate) vs.
SNR (signal to noise ratio).
In this presentation the effect of channel estimation errors on the energy efficiency of a down-link massive multiple-input multiple-output system is investigated and analyzed. The required down-link transmit power of the zero forcing (ZF) and maximum ratio transmission (MRT) precoding schemes are derived and analyzed under imperfect channel state information condition.
An Efficient Performance of Mimo - Ofdm Based Cognitieve Radio System for Arr...IOSR Journals
Abstract: The wireless channel is central within this context, thus estimating the channel is the key to make CR operational, taking in consideration that the transmission-reception technology is available. In this thesis, we design a MIMO system using OFDM modulation technology to transmit and receive two signals over the mobile wireless channel. First formulate the pilot design as a new optimization problem. We use MIMO concept to enhance system capacity and robustness of the wireless transmission. In Multi-Input Multi-Output (MIMO) based cognitive radio (CR) systems, with the increasing demand for data rate and reliability in Wireless communicationsand devices, several issues become very important like bandwidth efficiency, quality of service and radio coverage. In this new scheme, adaptive arrays are group-selected in the spatial domain. Simulation shows that the proposed system can get significant performance improvements over the conventional array based OFDM systems over frequency-selective multipath fading channels with cognitive radio (CR) system. Keywords: Cognitive radios, MIMO, OFDM, and Joint transmit and receive group selected arrays.
MIMO channels: optimizing throughput and reducing outage by increasing multip...TELKOMNIKA JOURNAL
The two main aims of deploying multiple input multiple out (MIMO) are to achieve spatial diversity (improves channel reliability) and spatial multiplexing (increase data throughput). Achieving both in a given system is impossible for now, and a trade-off has to be reached as they may be conflicting objectives. The basic concept of multiplexing: divide (multiplex) transmit a data stream several branches and transmit via several (independent) channels. In this paper, we focused mainly on achieving spatial multiplexing by modeling the channel using the diagonal Bell Labs space time scheme (D-BLAST) and the vertical Bell Labs space time architecture (V-BLAST) Matlab simulations results were a lso given to further compare the advantages of spatial multiplexing.
Improvement of MFSK -BER Performance Using MIMO Technology on Multipath Non L...theijes
Digital communications has evolved rapidly with a lot of success. The new trend seems to be the reinvention of already existing and even discredited or discarded theories or in this case, channels. Extensive research into optimizing or enhancing already existing schemes is still gaining momentum with practical results for all to experience and utilize. This paper describes the design and BER performance of an M-ary frequency shift keyed (FSK) signaling and demodulation scheme improved by MIMO antenna technology for wireless communications. MFSK and MIMO systems were briefly reviewed including AWGN, Non LOS fading and an important factor employed to estimate the performance of digital transmission. The research was performed using MATLAB for simulation and evaluation of the BER
Ijsrdv1 i2070Experimental Investigations of Chemical and Geotechnical Propert...ijsrd.com
Fly Ash generation and utilization both are expected to increase but the gap between them will also increase. Researchers are finding out new area for utilization of Fly Ash to minimize its environmental impact. One such area is Geotechnical Engineering. Black Cotton Soil is a problematic soil with respect to Soil-Structure interaction. In this paper, various properties of Black Cotton Soil like pH, plasticity index, volume change behavior and dry density are studied after mixing Fly Ash in different proportion and are presented. It can be concluded that 30% Fly Ash by weight mixed with Black Cotton soil gives optimum result for most of the properties.
Approximation of Gaussian derivatives for UWB communicationijsrd.com
UWB is a new interesting technology for wireless communications. It can replace traditionally carrier-based radio transmission by pulse-based transmission using ultrawide band frequency but at a very low energy. An important aspect of research in this domain is to find a pulse with an optimal shape, whose power spectral density respects and best fits emission limitation mask imposed by FCC. In this paper we review common used Gaussian pulses and its derivatives and the influence of shape factor, finding an optimal specific value for each derivative. Next, we search to obtain possible better pulse shapes as linear combinations of Gaussian derivatives. Older studies refer in one case to the same shape factor for all derivatives and in other case to higher factor for first derivative and smaller shape factors for subsequent derivatives. Our new idea is to use Gaussian derivatives, each with its specific optimal shape factor and to use a "trial and error" algorithm to obtain a linear combination pulse with better performance.
MESSAGING GATEWAY large business edition is an easy to use email virus protection that delivers effective and accurate antispam protection with no user peer user fees and available as a VMware-based virtual appliance Messaging gateway large business edition can be implemented on your existing hardware making it one of the most affordable gateway appliance solutions available.
Multicarrier modulation can be implemented by using Orthogonal Frequency Division Multiplexing (OFDM) to achieve utmost bandwidth exploitation and soaring alleviation attributes profile besides multipath fading. To support delay sensitive and band bandwidth demanding multimedia applications and internet services, MIMO in addition with other techniques can be used to achieve high capacity and reliability. To obtain high spatial rate by transmitting data on several antennas by using MIMO with OFDM results in reducing error recovery features and the equalization complexities arise by sending data on varying frequency levels. Three parameters frequency OFDM, Spatial (MIMO) and time (STC) can be used to achieve diversity in MIMO-OFDM. This technique is dynamic and well-known for services of wireless broadband access. MIMO if used with OFDM is highly beneficial for each scheme and provides high throughput. There are several space time block codes to exploit MIMO OFDM; one of the techniques is called Alamouti Codes. The paper investigates adaptive Alamouti Codes and their application in IEEE 802.11n.
Ber analysis of 2x2 mimo spatial multiplexing under awgn and rician channels ...ijwmn
Multiple-input–multiple-output (MIMO) wireless systems use multiple antennas at transmitting and
receiving end to offer improved capacity and data rate over single antenna systems in multipath channels.
In this paper we have investigated the Spatial Multiplexing technique of MIMO systems. Here different
fading channels like AWGN and Rician are used for analysis purpose. Moreover we analyzed the technique
using high level modulations (i.e. M-PSK for different values of M). Detection algorithms used are Zero-
Forcing and Minimum mean square estimator. Performance is analyzed in terms of BER (bit error rate) vs.
SNR (signal to noise ratio).
In this presentation the effect of channel estimation errors on the energy efficiency of a down-link massive multiple-input multiple-output system is investigated and analyzed. The required down-link transmit power of the zero forcing (ZF) and maximum ratio transmission (MRT) precoding schemes are derived and analyzed under imperfect channel state information condition.
An Efficient Performance of Mimo - Ofdm Based Cognitieve Radio System for Arr...IOSR Journals
Abstract: The wireless channel is central within this context, thus estimating the channel is the key to make CR operational, taking in consideration that the transmission-reception technology is available. In this thesis, we design a MIMO system using OFDM modulation technology to transmit and receive two signals over the mobile wireless channel. First formulate the pilot design as a new optimization problem. We use MIMO concept to enhance system capacity and robustness of the wireless transmission. In Multi-Input Multi-Output (MIMO) based cognitive radio (CR) systems, with the increasing demand for data rate and reliability in Wireless communicationsand devices, several issues become very important like bandwidth efficiency, quality of service and radio coverage. In this new scheme, adaptive arrays are group-selected in the spatial domain. Simulation shows that the proposed system can get significant performance improvements over the conventional array based OFDM systems over frequency-selective multipath fading channels with cognitive radio (CR) system. Keywords: Cognitive radios, MIMO, OFDM, and Joint transmit and receive group selected arrays.
MIMO channels: optimizing throughput and reducing outage by increasing multip...TELKOMNIKA JOURNAL
The two main aims of deploying multiple input multiple out (MIMO) are to achieve spatial diversity (improves channel reliability) and spatial multiplexing (increase data throughput). Achieving both in a given system is impossible for now, and a trade-off has to be reached as they may be conflicting objectives. The basic concept of multiplexing: divide (multiplex) transmit a data stream several branches and transmit via several (independent) channels. In this paper, we focused mainly on achieving spatial multiplexing by modeling the channel using the diagonal Bell Labs space time scheme (D-BLAST) and the vertical Bell Labs space time architecture (V-BLAST) Matlab simulations results were a lso given to further compare the advantages of spatial multiplexing.
Improvement of MFSK -BER Performance Using MIMO Technology on Multipath Non L...theijes
Digital communications has evolved rapidly with a lot of success. The new trend seems to be the reinvention of already existing and even discredited or discarded theories or in this case, channels. Extensive research into optimizing or enhancing already existing schemes is still gaining momentum with practical results for all to experience and utilize. This paper describes the design and BER performance of an M-ary frequency shift keyed (FSK) signaling and demodulation scheme improved by MIMO antenna technology for wireless communications. MFSK and MIMO systems were briefly reviewed including AWGN, Non LOS fading and an important factor employed to estimate the performance of digital transmission. The research was performed using MATLAB for simulation and evaluation of the BER
Ijsrdv1 i2070Experimental Investigations of Chemical and Geotechnical Propert...ijsrd.com
Fly Ash generation and utilization both are expected to increase but the gap between them will also increase. Researchers are finding out new area for utilization of Fly Ash to minimize its environmental impact. One such area is Geotechnical Engineering. Black Cotton Soil is a problematic soil with respect to Soil-Structure interaction. In this paper, various properties of Black Cotton Soil like pH, plasticity index, volume change behavior and dry density are studied after mixing Fly Ash in different proportion and are presented. It can be concluded that 30% Fly Ash by weight mixed with Black Cotton soil gives optimum result for most of the properties.
Approximation of Gaussian derivatives for UWB communicationijsrd.com
UWB is a new interesting technology for wireless communications. It can replace traditionally carrier-based radio transmission by pulse-based transmission using ultrawide band frequency but at a very low energy. An important aspect of research in this domain is to find a pulse with an optimal shape, whose power spectral density respects and best fits emission limitation mask imposed by FCC. In this paper we review common used Gaussian pulses and its derivatives and the influence of shape factor, finding an optimal specific value for each derivative. Next, we search to obtain possible better pulse shapes as linear combinations of Gaussian derivatives. Older studies refer in one case to the same shape factor for all derivatives and in other case to higher factor for first derivative and smaller shape factors for subsequent derivatives. Our new idea is to use Gaussian derivatives, each with its specific optimal shape factor and to use a "trial and error" algorithm to obtain a linear combination pulse with better performance.
MESSAGING GATEWAY large business edition is an easy to use email virus protection that delivers effective and accurate antispam protection with no user peer user fees and available as a VMware-based virtual appliance Messaging gateway large business edition can be implemented on your existing hardware making it one of the most affordable gateway appliance solutions available.
An Impact of Land use and Transportation - A case study of Sanand Areaijsrd.com
Land use and Transportation Systems play definitive roles in shaping the city or town. This paper explores the impact of land use and transportation system on the city population and the land price. Theory discussed is located within the Indian context, and utilizes the example of the Sanand area in Gujarat State to elucidate how landuse and transportation system impact on the characteristics of the area.
Experimental Investigation on Use of Honge(Pongamia) Biodiesel on Multi-cylin...ijsrd.com
Biodiesel is a fatty acid alkyl ester which is renewable, biodegradable and non toxic fuel which can be derived from any vegetable oil by transesterifiaction process. Biodiesel has become a key source as a substitution fuel and is making its place as a key future renewable energy source. Biodiesel derived from vegetable oils are quite promising alternative fuels for diesel engines. Use of vegetable oils in diesel engines leads to slightly inferior performance and higher smoke emissions due to their high viscosity. The performance of vegetable oils can be improved by modifying them through the Transesterification process. In the present work, the performance of single cylinder direct injection diesel engine using honge as fuel was evaluated for its performance, emission and combustion characteristics. The properties of honge thus obtained are comparable with ASTM biodiesel standards. The produced honge biodiesel was tested for their use as a substitute fuel for diesel engine. Tests have been conducted at different varying load of biodiesel, at 60% throttle. The performance parameters elucidated includes brake thermal efficiency, specific fuel consumption, torque, also emission characteristics against varying Brake Power (BP) and combustion characteristics against crank angle.
A NEW PROPOSED SYMMETRIC KEY ALGORITHM FOR MODERN CRYPTOGRAPHICijsrd.com
Communication in any language between two or more persons is like a plaintext or simple text. That means any person knowing that language can easily understand this plain text until this plaintext is codified in some manner. So, it is important to implement the coding techniques to ensure that information is hidden from everyone for whom it is not intended. So, that only authenticated person will be allowed to access the information. Cryptography is the art and science of achieving security by the encoding of messages in an unreadable form. Cryptography derives from the Greek word; the word "crypto" comes from kruptos, which means "hidden" and graphy means "writing". Thus, Cryptography is the practice and study of the hiding messages. Today, the cryptography is considered as branch for both the Computer Science and mathematics, which will related to the information theory.
Machining of Sic - Metal Matrix Composite (MMC) by Polycrystalline Diamond (P...ijsrd.com
In this paper, wear of polycrystalline diamond (PCD) cutting tools and the surface integrity during machining of SiC – Metal Matrix Composite (MMC) is discussed. An attempt is made to establish relation between the hardness of the tool and the flank wear. A newly developed PCD tool, which is superior in hardness with lower flank wear than the conventional tools is introduced. During machining with PCD tools, the severity of transfer material on the tools increased significantly with cutting distance and cutting speed. The superior surface finish obtained with the PCD tools cannot be merely explained by their low wear. The low degree of adhesion that these tools had with the work material appeared to be the main reason for the superior surface obtained at both low and high cutting speeds. At low cutting speed, when the use of coolant resulted in a marked reduction in the amount of work material on the machined work pieces, high Ra and P-V values can be obtained.
Design and Simulation Low power SRAM Circuitsijsrd.com
SRAMs), focusing on optimizing delay and power. As the scaling trends in the speed and power of SRAMs with size and technology and find that the SRAM delay scales as the logarithm of its size as long as the interconnect delay is negligible. Non-scaling of threshold mismatches with process scaling, causes the signal swings in the bitlines and data lines also not to scale, leading to an increase in the relative delay of an SRAM, across technology generations. Appropriate methods for reduction of power consumption were studied such as capacitance reduction, very low operating voltages, DC and AC current reduction and suppression of leakage currents to name a few.. Many of reviewed techniques are applicable to other applications such as ASICs, DSPs, etc. Battery and solar-cell operation requires an operating voltage environment in low voltage area. These conditions demand new design approaches and more sophisticated concepts to retain high device reliability. The proposed techniques (USRS and LPRS) are topology based and hence easier to implement.
Use of Seven Quality Tools to Improve Quality and Productivity in Industryijsrd.com
The main aim of this paper is to provide the use of 7-Quality Tools (QC) to improve the quality of products in any industry. It included different methods and tools by which some organization can keep check on quality. Some simple techniques like basic Quality Control(QC) provide simple and effective way to improve the quality.The work shows continuous use of these tools upgrades the personnel characteristics of the people involved. It enhances their ability to think generate ideas, solve problem and do proper planning. The development of people improves the internal environment of the organization, Which plays a major role in the total Quality Culture.
MIMO-OFDM (Multi Input Multi Output- Orthogonal Frequency Division Multiplexing) system is very popular technique for mobile communication. We found that Ergodic channel capacity has some limitation in MIMO-OFDM system. So Ergodic channel capacity optimization is necessary to improve the performance of MIMO-OFDM System.
A Novel Technique to Solve Mathematical Model of Pressure Swing Adsorption Sy...ijsrd.com
The mathematical modeling of a Pressure Swing Adsorption (PSA) system is discussed in detail for the Skarstrom cycle of two-bed process. The system is used to get pure oxygen product from the air with the use of zeolite 13X as an adsorbent. There are complex partial differential equations (pdes) which may not solve by analytical methods. There is no provision for solving it in any other software other than Matlab. All the equations are rearranged and written into dimensionless quantities, to make it easier. It is a novel technique of solving these complex PDEs. After that we have converted these PDEs into ODEs (Ordinary Differential Equations) by using OCFE (Orthogonal Collocation on Finite Elements) method. Now, these ODEs can be solved using different solvers like ode23, ode45, ode113, ode15s, ode23s, ode23t, ode23tb. The results obtained by this model will be compared to real industrial data.
Detecting Wormhole Attack in Mobile Ad-hoc Networks: A Surveyijsrd.com
A Mobile Ad Hoc Network (MANET) is a self organizing, infrastructure less, multi-hop network. The wireless and distributed nature of MANETs poses a great challenge to system security designers. Ad hoc networks are by nature very open to anyone. Anyone with the proper hardware and knowledge of the network topology and protocols can connect to the network. This allows potential attackers to infiltrate the network and carry out attacks on its participants with the purpose of stealing or altering information. A specific type of attack, the Wormhole attack does not require exploiting any nodes in the network and can interfere with the route establishment process. It does not require any cryptographic primitives. This attack targets specifically routing control packets, the nodes that are close to the attackers are shielded from any alternative routes with more than one or two hops to the remote location. All routes are thus directed to the wormhole established by the attackers. The entire routing system in MANET can even be brought down using the wormhole attack.
Simulation of 3 bit Flash ADC in 0.18μmTechnology using NG SPICE Tool for Hig...ijsrd.com
This paper provides the basic simulation result for the 3 bit flash type ADC in 0.18μm technology using the NG Spice device simulator tool. It includes two stages, first stage includes 7 comparators and second stage has a thermometer encoder. The simulation is done in NG spice tool developed by university of California at Berkeley (USA).The response time of the comparator and ADC are 3.7ns and 4.9ns respectively with 50.01μw power dissipation which makes the ADC more suitable for high speed application with lower power devices.
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.
Error Rate Analysis of MIMO System Using V Blast Detection Technique in Fadin...IJERA Editor
Wireless communication system with multi- antenna arrays has been a field of intensive analysis on the last years. The appliance of multiple sending antennas and Receiving Antennas either side will considerably enhance the data rate and rate. The review of the performance limitations of MIMO system becomes vital since it will provide lot ideas in understanding and planning the important life MIMO systems. Vertical Bell Laboratories layered space Time (V-BLAST). The thought behind Multiple Input and Multiple Output system is that the signals on the transmitter antennas at one finish and also the receiver antennas at the opposite finish are correlative in such how that the performance (Bit Error Rate or BER) or the info rate (bits/sec) of the wireless communication system for every MIMO subscriber are improved. During this paper we tend to are proposing a technique that evaluates the performance of V-BLAST MIMO system in several thought of Rayleigh attenuation surroundings to urge higher performance of the system. In V- BLAST MIMO system a number of linear detection techniques will be used for interference cancellation. At this point we are using MMSE-IC for the same. Our expected system provide higher error rate performance with the used of matched filter at receiver aspect .The projected system compared within the presence of AWGN. Now matched filter applied on V- BLAST MIMO with MMSE-IC system in fading diversity surroundings.
There are many types of wireless channel impairments such as noise, path loss, shadowing, and fading and impairment Mitigation techniques should be adopted according to system requirements and channel environments.
IMPLEMENTATION OF LINEAR DETECTION TECHNIQUES TO OVERCOME CHANNEL EFFECTS IN ...IJCI JOURNAL
Spatial diversity technique enables improvement in quality and reliability of wireless link. Antenna
diversity along with understanding effects of channel on transmitted signal and methods to overcome the
channel impairment plays an important role in wireless communication where sharing of channel occurs
between users. In this paper single input single output system (SISO) is compared with multiple input
multiple output system (MIMO) in terms of bit error rate performance. Bit error rate performance is also
evaluated for MIMO with least squares (LS) and Minimum mean square error (MMSE) linear detection.
Further analysis and simulation is done to understand the effect of channel imperfections on BER.
MIMO Channel Estimation Using the LS and MMSE AlgorithmIOSRJECE
Wireless Communication Technology has developed over the past few yearsfor other objectives.The Multiple InputMultiple Output (MIMO) is one of techniques that is used to enhancethe data rates, in which multiple antennas are employed both the transmitter and receiver. Multiple signals are transmitted from different antennas at the transmitter using the same frequency and separated space. Various channel estimation techniques are employed in order to judge the physical effects of the medium present. In this paper, we analyze and implementvarious estimation techniques for MIMO Systems such as Least Squares (LS), Minimum Mean Square Error (MMSE),these techniques are therefore compared to effectively estimate the channel in MIMO System. The results demonstrate that SNR required to support different values of bit error rate varies depending on different low correlation between the transmitting and the receiving antennas .In addition, it is illustrated that when the number of transmitter and receiver antennas increases, the performance of TBCE schemes significantly improves. The Same behavior isalso observed for MIMO system. Performance of both MMSE and LSestimation are the same for allkinds of modulation at small value of SNR but the more we increase the SNR value the more performance gap goes on increasing.
Bit Error Rate Performance of MIMO Spatial Multiplexing with MPSK Modulation ...ijsrd.com
Wireless communication is one of the most effective areas of technology development of our time. Wireless communications today covers a very wide array of applications. In this, we study the performance of general MIMO system, the general V-BLAST architecture with MPSK Modulation in Rayleigh fading channels. Based on bit error rate, we show the performance of the 2x2 schemes with MPSK Modulation in noisy environment. We also show the bit error rate performance of 2x2, 3x3, 4x4 systems with BPSK modulation. We see that the bit error rate performance of 2x2 systems with QPSK modulation gives us the best performance among other schemes analysed here.
Transmit antenna subset selection in mimo ofdm system using adaptive mutuatio...ijmnct
Multiple input multiple output techniques are considered attractive for future wireless communication
systems, due to the continuing demand for high data rates, spectral efficiency, suppress interference ability
and robustness of transmission. MIMO-OFDM is very helpful to transmit high data rate in wireless
transmission and provides good maximum system capacity by getting the advantages of both MIMO and
OFDM. The main problem in this system is that increase in number of transmit and receive antennas lead
to hardware complexity. To tackle this issue, an effective optimal transmit antenna subset selection method
is proposed in paper with the aid of Adaptive Mutation Genetic Algorithm (AGA). Here, the selection of
transmit antenna subsets are done by the adaptive mutation of Genetic Algorithm in MIMO-OFDM system.
For all the mutation points, the fitness function are evaluated and from that value, best fitness based
mutation points are chosen. After the selection of best mutation points, the mutation process is carried out,
accordingly. The implementation of proposed work is done in the working platform MATLAB and the
performance are evaluated with various selection of transmit antenna subsets. Moreover, the comparison
results between the existing GA with mutation and the proposed GA with adaptive mutation are discussed.
Hence, using the proposed work, the selection of transmit antenna with the maximum capacity is made and
which leads to the reduced hardware complexity and undisturbed data rate in the MIMO-OFDM system
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
Min input and min output of the system can be conduct by the process of interest in the process of view of synchronisation and software Engineer at the system can be a good idea for this colour combination of view of the best part of the system can be conduct by the process of view till now I'm interested for the system based engineering and technology related issues in college and software engineer h today’s increasing demand for security, especially in public places such as
airports, train stations, supermarkets, schools, and crowded street, surveillance cameras are
used for monitoring daily activities and detecting abnormal events. This task focuses on the
localization of anomalies using both temporal and partial information in videos. Anomalies
can be defined as events deviating from normal behavior [1], e.g., fighting, sneaking,
or unattended bags at an airport. The purpose of using surveillance cameras is the early
detection of anomalous human behaviors. This is a critical task in many cases where human
intervention is necessary, e.g., for crime prevention or countering terrorism. However,
this process requires labor-intensive and continuous human attention, which is a tedious
process, since abnormal events only happen 0.01% of the time and 99.9% of the surveillance
time is wasted [2]. Moreover, a surveillance system produces a lot of redundant video data,
which require unnecessary storage space. For reducing human errors and storage costs, it
is necessary to build an efficient surveillance system for detecting any strange behaviors
that may lead to dangerous situations. This requires deep and comprehensive study of
human activity recognition, to understand the features representative of each action.
Anomaly detection in video has a wide range of applications, such as for traffic
accident detection, criminal activity detection, and illegal activity detection. In addition,
detecting anomalous items or abandoned objects, such as guns or knifes, is necessary in
sensitive area
Similar to A New Transmission Scheme for MIMO – OFDM (20)
Due to availability of internet and evolution of embedded devices, Internet of things can be useful to contribute in energy domain. The Internet of Things (IoT) will deliver a smarter grid to enable more information and connectivity throughout the infrastructure and to homes. Through the IoT, consumers, manufacturers and utility providers will come across new ways to manage devices and ultimately conserve resources and save money by using smart meters, home gateways, smart plugs and connected appliances. The future smart home, various devices will be able to measure and share their energy consumption, and actively participate in house-wide or building wide energy management systems. This paper discusses the different approaches being taken worldwide to connect the smart grid. Full system solutions can be developed by combining hardware and software to address some of the challenges in building a smarter and more connected smart grid.
A Survey Report on : Security & Challenges in Internet of Thingsijsrd.com
In the era of computing technology, Internet of Things (IoT) devices are now popular in each and every domains like e-governance, e-Health, e-Home, e-Commerce, and e-Trafficking etc. Iot is spreading from small to large applications in all fields like Smart Cities, Smart Grids, Smart Transportation. As on one side IoT provide facilities and services for the society. On the other hand, IoT security is also a crucial issues.IoT security is an area which totally concerned for giving security to connected devices and networks in the IoT .As, IoT is vast area with usability, performance, security, and reliability as a major challenges in it. The growth of the IoT is exponentially increases as driven by market pressures, which proportionally increases the security threats involved in IoT The relationship between the security and billions of devices connecting to the Internet cannot be described with existing mathematical methods. In this paper, we explore the opportunities possible in the IoT with security threats and challenges associated with it.
In today’s emerging world of Internet, each and every thing is supposed to be in connected mode with the help of billions of smart devices. By connecting all the devises used in our day to day life, make our life trouble less and easy. We are incorporated in a world where we are used to have smart phones, smart cars, smart gadgets, smart homes and smart cities. Different institutes and researchers are working for creating a smart world for us but real question which we need to emphasis on is how to make dumb devises talk with uncommon hardware and communication technology. For the same what kind of mechanism to use with various protocols and less human interaction. The purpose is to provide the key area for application of IoT and a platform on which various devices having different mechanism and protocols can communicate with an integrated architecture.
Study on Issues in Managing and Protecting Data of IOTijsrd.com
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Interactive Technologies for Improving Quality of Education to Build Collabor...ijsrd.com
Today with advancement in Information Communication Technology (ICT) the way the education is being delivered is seeing a paradigm shift from boring classroom lectures to interactive applications such as 2-D and 3-D learning content, animations, live videos, response systems, interactive panels, education games, virtual laboratories and collaborative research (data gathering and analysis) etc. Engineering is emerging with more innovative solutions in the field of education and bringing out their innovative products to improve education delivery. The academic institutes which were once hesitant to use such technology are now looking forward to such innovations. They are adopting the new ways as they are realizing the vast benefits of using such methods and technology. The benefits are better comprehensibility, improved learning efficiency of students, and access to vast knowledge resources, geographical reach, quick feedback, accountability and quality research. This paper focuses on how engineering can leverage the latest technology and build a collaborative learning environment which can then be integrated with the national e-learning grid.
Internet of Things - Paradigm Shift of Future Internet Application for Specia...ijsrd.com
In the world more than 15% people are living with disability that also include children below age of 10 years. Due to lack of independent support services specially abled (handicap) people overly rely on other people for their basic needs, that excludes them from being financially and socially active. The Internet of Things (IoT) can give support system and a better quality of life as well as participation in routine and day to day life. For this purpose, the future solutions for current problems has been introduced in this paper. Daunting challenges have been considered as future research and glimpse of the IoT for specially abled person is given in the paper.
A Study of the Adverse Effects of IoT on Student's Lifeijsrd.com
Internet of things (IoT) is the most powerful invention and if used in the positive direction, internet can prove to be very productive. But, now a days, due to the social networking sites such as Face book, WhatsApp, twitter, hike etc. internet is producing adverse effects on the student life, especially those students studying at college Level. As it is rightly said, something which has some positive effects also has some of the negative effects on the other hand. In this article, we are discussing some adverse effects of IoT on student’s life.
Pedagogy for Effective use of ICT in English Language Learningijsrd.com
The use of information and communications technology (ICT) in education is a relatively new phenomenon and it has been the educational researchers' focus of attention for more than two decades. Educators and researchers examine the challenges of using ICT and think of new ways to integrate ICT into the curriculum. However, there are some barriers for the teachers that prevent them to use ICT in the classroom and develop supporting materials through ICT. The purpose of this study is to examine the high school English teachers’ perceptions of the factors discouraging teachers to use ICT in the classroom.
In recent years usage of private vehicles create urban traffic more and more crowded. As result traffic becomes one of the important problems in big cities in all over the world. Some of the traffic concerns are traffic jam and accidents which have caused a huge waste of time, more fuel consumption and more pollution. Time is very important parameter in routine life. The main problem faced by the people is real time routing. Our solution Virtual Eye will provide the current updates as in the real time scenario of the specific route. This research paper presents smart traffic navigation system, based on Internet of Things, which is featured by low cost, high compatibility, easy to upgrade, to replace traditional traffic management system and the proposed system can improve road traffic tremendously.
Ontological Model of Educational Programs in Computer Science (Bachelor and M...ijsrd.com
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Lately the concept of Internet of Things (IoT) is being more elaborated and devices and databases are proposed thereby to meet the need of an Internet of Things scenario. IoT is being considered to be an integral part of smart house where devices will be connected to each other and also react upon certain environmental input. This will eventually include the home refrigerator, air conditioner, lights, heater and such other home appliances. Therefore, we focus our research on the database part for such an IoT’ fridge which we called as smart Fridge. We describe the potentials achievable through a database for an IoT refrigerator to manage the refrigerator food and also aid the creation of a monthly budget of the house for a family. The paper aims at the data management issue based on a proposed design for an intelligent refrigerator leveraging the sensor technology and the wireless communication technology. The refrigerator which identifies products by reading the barcodes or RFID tags is proposed to order the required products by connecting to the Internet. Thus the goal of this paper is to minimize human interaction to maintain the daily life events.
DESIGN AND ANALYSIS OF DOUBLE WISHBONE SUSPENSION SYSTEM USING FINITE ELEMENT...ijsrd.com
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A Review: Microwave Energy for materials processingijsrd.com
Microwave energy is a latest largest growing technique for material processing. This paper presents a review of microwave technologies used for material processing and its use for industrial applications. Advantages in using microwave energy for processing material include rapid heating, high heating efficiency, heating uniformity and clean energy. The microwave heating has various characteristics and due to which it has been become popular for heating low temperature applications to high temperature applications. In recent years this novel technique has been successfully utilized for the processing of metallic materials. Many researchers have reported microwave energy for sintering, joining and cladding of metallic materials. The aim of this paper is to show the use of microwave energy not only for non-metallic materials but also the metallic materials. The ability to process metals with microwave could assist in the manufacturing of high performance metal parts desired in many industries, for example in automotive and aeronautical industries.
Web Usage Mining: A Survey on User's Navigation Pattern from Web Logsijsrd.com
With an expontial growth of World Wide Web, there are so many information overloaded and it became hard to find out data according to need. Web usage mining is a part of web mining, which deal with automatic discovery of user navigation pattern from web log. This paper presents an overview of web mining and also provide navigation pattern from classification and clustering algorithm for web usage mining. Web usage mining contain three important task namely data preprocessing, pattern discovery and pattern analysis based on discovered pattern. And also contain the comparative study of web mining techniques.
APPLICATION OF STATCOM to IMPROVED DYNAMIC PERFORMANCE OF POWER SYSTEMijsrd.com
Application of FACTS controller called Static Synchronous Compensator STATCOM to improve the performance of power grid with Wind Farms is investigated .The essential feature of the STATCOM is that it has the ability to absorb or inject fastly the reactive power with power grid . Therefore the voltage regulation of the power grid with STATCOM FACTS device is achieved. Moreover restoring the stability of the power system having wind farm after occurring severe disturbance such as faults or wind farm mechanical power variation is obtained with STATCOM controller . The dynamic model of the power system having wind farm controlled by proposed STATCOM is developed . To validate the powerful of the STATCOM FACTS controller, the studied power system is simulated and subjected to different severe disturbances. The results prove the effectiveness of the proposed STATCOM controller in terms of fast damping the power system oscillations and restoring the power system stability.
Making model of dual axis solar tracking with Maximum Power Point Trackingijsrd.com
Now a days solar harvesting is more popular. As the popularity become higher the material quality and solar tracking methods are more improved. There are several factors affecting the solar system. Major influence on solar cell, intensity of source radiation and storage techniques The materials used in solar cell manufacturing limit the efficiency of solar cell. This makes it particularly difficult to make considerable improvements in the performance of the cell, and hence restricts the efficiency of the overall collection process. Therefore, the most attainable maximum power point tracking method of improving the performance of solar power collection is to increase the mean intensity of radiation received from the source used. The purposed of tracking system controls elevation and orientation angles of solar panels such that the panels always maintain perpendicular to the sunlight. The measured variables of our automatic system were compared with those of a fixed angle PV system. As a result of the experiment, the voltage generated by the proposed tracking system has an overall of about 28.11% more than the fixed angle PV system. There are three major approaches for maximizing power extraction in medium and large scale systems. They are sun tracking, maximum power point (MPP) tracking or both.
A REVIEW PAPER ON PERFORMANCE AND EMISSION TEST OF 4 STROKE DIESEL ENGINE USI...ijsrd.com
In day today's relevance, it is mandatory to device the usage of diesel in an economic way. In present scenario, the very low combustion efficiency of CI engine leads to poor performance of engine and produces emission due to incomplete combustion. Study of research papers is focused on the improvement in efficiency of the engine and reduction in emissions by adding ethanol in a diesel with different blends like 5%, 10%, 15%, 20%, 25% and 30% by volume. The performance and emission characteristics of the engine are tested observed using blended fuels and comparative assessment is done with the performance and emission characteristics of engine using pure diesel.
Study and Review on Various Current Comparatorsijsrd.com
This paper presents study and review on various current comparators. It also describes low voltage current comparator using flipped voltage follower (FVF) to obtain the single supply voltage. This circuit has short propagation delay and occupies a small chip area as compare to other current comparators. The results of this circuit has obtained using PSpice simulator for 0.18 μm CMOS technology and a comparison has been performed with its non FVF counterpart to contrast its effectiveness, simplicity, compactness and low power consumption.
Reducing Silicon Real Estate and Switching Activity Using Low Power Test Patt...ijsrd.com
Power dissipation is a challenging problem for today's system-on-chip design and test. This paper presents a novel architecture which generates the test patterns with reduced switching activities; it has the advantage of low test power and low hardware overhead. The proposed LP-TPG (test pattern generator) structure consists of modified low power linear feedback shift register (LP-LFSR), m-bit counter, gray counter, NOR-gate structure and XOR-array. The seed generated from LP-LFSR is EXCLUSIVE-OR ed with the data generated from gray code generator. The XOR result of the sequence is single input changing (SIC) sequence, in turn reduces the switching activity and so power dissipation will be very less. The proposed architecture is simulated using Modelsim and synthesized using Xilinx ISE9.2.The Xilinx chip scope tool will be used to test the logic running on FPGA.
Defending Reactive Jammers in WSN using a Trigger Identification Service.ijsrd.com
In the last decade, the greatest threat to the wireless sensor network has been Reactive Jamming Attack because it is difficult to be disclosed and defend as well as due to its mass destruction to legitimate sensor communications. As discussed above about the Reactive Jammers Nodes, a new scheme to deactivate them efficiently is by identifying all trigger nodes, where transmissions invoke the jammer nodes, which has been proposed and developed. Due to this identification mechanism, many existing reactive jamming defending schemes can be benefited. This Trigger Identification can also work as an application layer .In this paper, on one side we provide the several optimization problems to provide complete trigger identification service framework for unreliable wireless sensor networks and on the other side we also provide an improved algorithm with regard to two sophisticated jamming models, in order to enhance its robustness for various network scenarios.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
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Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
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Final project report on grocery store management system..pdfKamal Acharya
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Author: Robbie Edward Sayers
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(C) 2024 Robbie E. Sayers
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Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
1. IJSRD - International Journal for Scientific Research & Development| Vol. 1, Issue 2, 2013 | ISSN (online): 2321-0613
All rights reserved by www.ijsrd.com 83
A New Transmission Scheme for MIMO – OFDM
Kushal V. Patel1
Mitesh D. Patel 2
1
PG Student, E.C. Department
2
Associate Professor, E.C. Department
1,2
KITRC, Kalol, Gujarat, India
Abstract— This contribution introduces a new transmission
scheme for multiple-input multiple-output (MIMO)
Orthogonal Frequency Division Multiplexing (OFDM)
systems. The new scheme is efficient and suitable
especially for symmetric channels such as the link between
two base stations or between two antennas on radio beam
transmission. This survey Paper presents the performance
analysis of V-BLAST based multiple inputs multiple output
orthogonal frequency division multiplexing (MIMO-
OFDM) system with respect to bit error rate per signal to
noise ratio (BER/SNR) for various detection techniques. A
2X2 MIMO-OFDM system is used for the performance
evaluation. The simulation results shows that the
performance of V-BLAST based detection techniques is
much better than the conventional methods.
Alamouti Space Time Block Code (STBC)
scheme is used with orthogonal designs over multiple
antennas which showed simulated results are identical to
expected theoretical results. With this technique both Bit
Error Rate (BER) and maximum diversity gain are achieved
by increasing number of antennas on either side. This
scheme is efficient in all the applications where system
capacity is limited by multipath fading.
Keywords: Multiple Input Multiple Output (MIMO),
OFDM, STBC, Bit Error Rate (BER), Maximum Receiving
Ratio Combining (MRRC), Alamouti Scheme, V-BLAST.
I. INTRODUCTION
During the past decades, wireless communication has
benefitted from substantial advances and it is considered as
the key enabling technique of innovative future consumer
products. High transmission data rate, spectral efficiency
and reliability are necessary for future wireless
communication system. Unlike Gaussian channels, wireless
channels suffer from attenuation due to multipath in the
channel. Multiple copies of a single transmission arrive at
the receiver at slightly different times. Without diversity
techniques, severe attenuation makes it difficult for the
receiver to determine the transmitted signal [1].
Specifically, the employment of multiple antennas at both
the transmitter and the receiver, which is widely referred to
as the MIMO techniques, constitutes a cost-effective
approach to high throughput wireless communication and
remote sensing. The concept MIMO for both wired and
wireless systems was first introduced by Jack Winter in
1987 for two basic communication systems. The first was
for communication between multiple mobiles and a base
station with multiple antennas and the second for
communication between two mobiles each with multiple
antennas. Where, he introduced a technique of transmitting
data from multiple users over the same frequency/time
channel using multiple antennas at both the transmitter and
receiver ends. In 1996, Raleigh proposed new approaches
for improving the efficiency of MIMO systems which
inspired numerous further contributions for two suitable
architectures for its realization known as Vertical Bell-Labs
Layered Space-Time (V-BLAST) algorithm has been
proposed by Foschini, which is capable of achieving a
substantial part of the MIMO capacity. It is capable of
achieving high spectral efficiency which being relatively
simple to implement. The basic motive was to increase the
data rate in a constrained spectrum. The promises of
information theoretic MIMO analysis for the channel
capacity were the main trigger for this enthusiasm and also
ignited the study of related area such as MIMO channel
modeling Space time signal processing, Space – Time
coding etc. The objective of such multi-channel
diagonalization is to partition or distribute multi user signals
into disjoint space and resultant channel gains are
maximized to optimize the overall system capacity under
the constraint of a fixed transmit power. Also improve the
quality (BER).
II. MIMO CHANNEL MODELS
MIMO System is an extension of smart antennas systems.
Traditional smart antenna system employs multiple antennas
at the receiver. Whereas in a general MIMO system multiple
antennas are employed both at the transmitter and the
receiver. The addition of multiple antennas at the transmitter
combined with advanced signal processing algorithms at the
transmitter and the receiver yields significant advantage
over traditional smart antenna systems – both in terms of
capacity and diversity advantage.
A MIMO channel is a wireless link between M
transmits and N receive antennas. It consists of MN
elements that represent the MIMO channel coefficients. The
multiple transmit and receive antennas could belong to a
single user modem or it could be distributed among
different users. The later configuration is called distributed
MIMO and cooperative communications. Statistical MIMO
channel models offer flexibility in selecting the channel
parameters. Temporal and spatial correlations. Fig.1(a), (b),
(c) and (d) shows conceptual diagram of existing
2. A New Transmission Scheme for MIMO - OFDM
(IJSRD/Vol. 1/Issue 2/2013/0009)
All rights reserved by www.ijsrd.com
84
technology, smart antenna system and MIMO channels
respectively.
Figure 1 (a) SISO (b) SIMO (c) MISO [1]
Figure.2 : (d) MIMO system model [1]
III. MIMO SYSTEM CHANNEL CAPACITY
Figure.3 : MIMO Channel
Multipath propagation has long been regarded as
“impairment” because it causes signal fading. To mitigate
this problem diversity technique were developed. Antenna
diversity is a widespread form of diversity.
Channel capacity is the maximum information rate that can
be transmitted and received with arbitrarily low probability
of error at the receiver. A common representation of the
channel capacity is within a unit bandwidth of the channel
and can be expressed in bps/Hz. MIMO channel capacity
depends heavily on the statistical properties and antenna
element correlations of the channel.
C = B (1)
When multiple antennas are used, channel faces multiple
input and output, and its capacity in determined by extended
Shannon’s capacity. Antenna with input from transmitter
and output in a receiver channel is expressed as
matrix of channel H.
The capacity of a MIMO channel can be estimated by the
following equation:
C= (2)
Where H is channel matrix, is covariance of
input signal x, is transpose conjugate of H matrix and
is the variance of the uncorrelated and Gaussian noise.
To achieve more precise results linear transformation at both
transmitter and receiver can be performed by converting
MIMO channel ( , ) to a SISO sub channel min ( , ).
According to singular value decomposition (SVD) every
matrix can be decomposed. Suppose the channel matrix H
transformation is given by
H = UD
Where the matrix U is x matrix, V is x matrix
and D is non-negative diagonal matrix of x .
Therefore capacity of N SISO sub channels is sum of
individual capacity and results the total MIMO capacity.
IV. DIVERSITY IMPROVEMENT TECHNIQUES
One of the methods to increase the capacity in MIMO
system is through diversity technique. Diversity is defined
as a method in which transmitter sends multiple copies of
same information signal over two or more channels and
proper combining of signal is done by a receiver. When the
replicas of signal are transmitted the probability that the
signal will fade decreases exponentially. So diversity
techniques enhance the performance of the system over
fading channels.
Maximum Ratio Receive Combining:A.
To eliminate the effect of multipath fading antenna diversity
is practical, effective and commonly used technique.
MRRC is classical receive diversity technique, which uses
the multiple antenna at the receiver and performs combining
or selection and switching to improve the quality of
received signal. Since the cost, size and power are the
important factors to be considered, MRRC uses selection
and switching circuit in the receiver which makes it larger
in size and costly. Due to this reason transmit diversity
schemes are found more attractive than the receive
diversity.
Figure .4: Two branches MRRC [2]
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At a time t signal s1 is transmitted and the channel is
presented with complex multiplicative distortion. Let h1 be
the channel between transmit antenna and receiving antenna
1 and h2 be channel between transmit antenna and receive
antenna 2 and are given by
, (3)
The received signal with added noise and interference are
below as shown in figure.
= , = (4)
Where and are noise and interference which is
assumed to be Gaussian distributed. The two branch MRRC
combiner combines the received signal as follow:
=
= ( + (5)
After combining the signal, maximum likelihood decision
rule is used at receiver to choose the signal which symbol
was actually transmitted.
Choose if and only if
( + -1) + , ( + -1) + +
, (6)
Where, , is the square Euclidean
distance between signals and Calculated by the
following:
, = ( (7)
Finally the maximum likelihood detector will produce the
signal which is maximum likelihood estimate of .
ALAMOUTI SCHEMEB.
The new transmit diversity scheme was introduced by
Alamouti known as Alamouti scheme. Alamouti scheme
uses two transmit antenna and receive antenna and can
have a maximum diversity order of 2 . Alamouti scheme
has the rate of unity i.e. full rate since it transmits two
symbols after every two time periods. This scheme is
efficient in all the applications where system capacity is
limited by multipath fading. Here we will explain only two
transmit and three receive antenna Alamouti scheme [2].
Two Transmit and three receive antennas: Alamouti scheme
works for two transmit and N number of receive antennas.
Let us consider case with two transmits and three receive
antennas. The transmission sequence of information symbol
for this configuration is identical with 2x1 and 2x2 antenna
scheme. Moreover it can be seen in Table 1.
Let and be the channel between two
transmit and three receive antenna which is also shown in
table 1 below:
Table 1: Channel parameter for 2 x 3 antennas.
Figure 5: Two Transmit and three receive Alamouti scheme
[2]
The received signals at time t and t+T are and
respectively, which can be seen in table 2.
Table 2: Received signals at three receive antennas.
Here,
(8)
Where are complex random
variables representing noise and interference. As it can be
seen in Figure 4-4, the received signals are combined and
following two signals are generated.
+
+ - (9)
Substituting eq (8) and eq (9) which gives eq (10):
=( + + +
+ + +
=( + + +
(10)
Performance of Alamouti scheme: The BER performance
comparison of Alamouti transmit diversity scheme with
coherent BPSK on slow Rayleigh fading channel with two
and four branch MRRC receive diversity scheme as shown
in figure. 5. It is assumed that the total transmit power in
two transmit antenna in Alamouti scheme is same as the
transmit power from single transmit antenna for MRRC.
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And also assumed that receiver has perfect knowledge of
the channel.
Figure .6 : BER performance comparison of BPSK
Alamouti scheme Rayleigh fading to MRRC.
The simulation output shows that the Alamouti scheme with
two transmit and a single receive antenna achieves the same
diversity order as MRRC scheme with one transmit and two
receive antenna as the slope of two curves are almost same.
However, it can be seen that Alamouti scheme is 3dB
behind than MRRC. The fact is that due to energy radiated
from two transmit antenna in Alamouti is half of the energy
radiated from a single antenna in MRRC. If the energy
radiated is same for each transmit antenna in Alamouti and
MRRC than resulting curve would be same.
V. V-BLAST ARCHITECTURE
Figure .7 : Block diagram of V-Blast architecture [4]
One of the earliest communication systems that were
proposed to take advantage of the promising capacity of
MIMO channels is the BLAST architecture. It achieves high
spectral efficiencies by spatially multiplexing coded or
uncoded symbols over the MIMO fading channel. Symbols
are transmitted through M antennas. Each receiver antenna
receives a superposition of faded symbols. The ML decoder
would select the set of symbols that are closest in Euclidean
distance to the received N signals. However, it is hard
to implement due to its exponential complexity. More
practical decoding architectures were proposed in the
literature.
V-BLAST TechniqueA.
The transmission is described as follows. A data stream is
demultiplexed into M sub-streams termed layers. For D-
BLAST at each transmission time, the layers circularly shift
across the M transmit antennas resulting in a diagonal
structure across space and time. On the other hand, the layers
are arranged horizontally across space and time for V-
BLAST and the cycling operation is removed before
transmission is shown in Fig.6. At the receiver, as mentioned
previously, the received signals at each receive antenna is a
superposition of M faded symbols plus additive white
Gaussian noise (AWGN). Although the layers are arranged
Differently for the two BLAST systems across space and
time, the detection process for both systems is performed
vertically for each received vector. Without loss of
generality, assume that the first symbol is to be detected. The
detection process consists of two main operations:
1) Interference suppression (nulling):
The suppression operation nulls out interference by
projecting the received vector onto the null subspace
(perpendicular subspace) of the subspace spanned by the
interfering signals. After that, normal detection of the first
symbol is performed [1].
2) Interference cancellation (subtraction):
The contribution of the detected symbol is subtracted from
the received vector [1].
BLAST detection algorithm combines linear
(interference suppression) and nonlinear (serial cancellation)
algorithms. This is similar to the decorrelating decision
feedback multiuser detection algorithm. A drawback of
BLAST algorithms is the propagation of decision errors.
Also, the Interference nulling operation requires that the
number of receive antennas be greater than or equal to the
number of transmit antennas. Furthermore, due to the
interference suppression, early detected symbols benefit
from lower receives diversity than later ones. Thus, the
algorithm results in unequal diversity advantage for each
symbol.
There are few differences between V-BLAST and
D-BLAST. While the layers of the V-BLAST can be coded
or uncoded, the D-BLAST is intended to be used only with
coded layers. This is the reason behind cycling which
provides more spatial diversity for each layer particularly
over slowly fading channels. Further, due to the diagonal
structure of D-BLAST, each layer benefits from the same
diversity advantage while V-BLAST layers have unequal
diversity advantages. However, DBLAST requires advanced
inter-stream coding techniques to optimize the performance
of the code across space and time. Finally, some space-time
is wasted at the start and the end of the burst for DBLAST.
V-BLAST takes a single data stream and
demultiplexed it into M sub-streams with M is the number
of transmitter antennas. Each sub-stream is encoded into
symbols and fed to a separate transmitter. The modulation
method in these systems usually is M Quadrature
Amplitude Modulation (MQAM). QAM combines phase
modulation with amplitude modulation, making it an
efficient method for transmitting data over a limited
bandwidth channel. BLAST's receivers operate co-channel,
each receiving the signals emanating from all M of the
transmitting antennas. For the sake of simplicity, it is also
assumed that the channel-time variation is negligible over
the L symbol periods in a burst.
Performance analysis of MIMO technology using V-B.
BLAST Techniques
1) Maximum Likelihood
ML is a non-linear detection technique. The BER/SNR
results of ML are better than MMSE detector but at the cost
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87
of additional complexity. So ML is used in applications
where high efficiency is requires. Now if we apply V-
BLAST algorithm on ML, the performance will be better
than ML detector [3].
2) Zero Forcing
Zero Forcing is a linear detection technique. The pseudo
inverse of the signal is applied to the received signal in
order to make a decision about one user. So the equation for
filter matrix G for zero forcing will be,
G = (11)
In this way the received signal is detected by zero forcing
detectors. If V-BLAST algorithm is applied on ZF detector,
equation 11 will be applied on ZF filter matrix. ZF with V-
BLAST shows better performance in comparison to normal
ZF in terms of BER/SNR [3].
3) Minimum Mean Square Error
MMSE is also a linear detection technique but more reliable
than ZF in case of noisy channel . MMSE does not apply
pseudo inverse of signal to make decision about one user,
instead it attenuates them to noise level thereby reducing
the diversity order. From the filter matrix for MMSE is,
G = (12)
Now V-BLAST algorithm can be applied over above filter
matrix and results can be generated [3].
VI. MATLAB RESULTS
Figure. 7: BER vs. SNR ratio for Alamouti 2*2
Figure .8: BER vs. SNR ratio for Alamouti 2*2
Figure .9: BER vs. SNR ratio for Alamouti 2*3
Comparison of BER performance with different Alamouti
scheme
Figure .10: Comparison of BER vs. SNR ratio for Alamouti
2*1, 2*2, 2*3
Figure .11: BER vs. SNR ratio for ZF and ZF-VBLAST
VII. CONCLUSION
In this paper, a detailed overview and analysis of OFDM,
MIMO and their combination with space time coding were
discussed. OFDM modulator and demodulator were
designed and simulated for single input and single output.
Space time coding (STC) has been implemented on MIMO
system and its BER checked. Simulated result for Alamouti
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88
2x1, 2x2 and 2x3 were compared with theoretical results of
one transmitter and one receiver (MRRC) and Alamouti
2x1. As diversity increases at the receiver end BER is
reduced. MIMO code was designed in such a way that it can
be raised up to 2xN receiver. The results of the simulations,
in which BER performance of different schemes is,
computed shows that MIMO-OFDM with space time
coding can provide high data rate transmission and there is
no need to increase the transmit power and expansion of
bandwidth. The results of the simulations, in which BER
performance of ZF-VBLAST and ZF is shown in the figure
1.11.
VIII. FUTURE WORK
The main focus of this paper was BER performance for
different Alamouti schemes. In future compare all the three
techniques of V-BLAST. In future one can combine MIMO
and OFDM and extend it for V-BLAST and Hybrid V-
BLAST ARCHITECTURE for higher diversity of antennas.
Moreover, further work can also be done to enhance the
capacity of the channel.
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mandloi, “Performance analysis of V-Blast Based
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