This document discusses a proposed space time block code-orthogonal frequency division multiplexing (STBC-OFDM) downlink baseband receiver for mobile wireless metropolitan area networks (WMANs). The proposed receiver applies STBC-OFDM techniques using two transmit antennas and one receive antenna to provide robust performance in outdoor mobile environments. It includes a simple and robust synchronizer and an accurate but affordable channel estimator to overcome challenges of multipath fading channels. Simulation results show the receiver can achieve a coded bit error rate of less than 10-6 for 16QAM modulation under vehicle speeds of 120 km/hr while supporting up to 27.32 Mb/s of uncoded data transmission. The receiver designed in a 90-nm CMOS
Performance Analysis of MIMO-OFDM System Using QOSTBC Code Structure for M-PSKCSCJournals
MIMO-OFDM system has been currently recognized as one of the most competitive technology for 4G mobile wireless systems. MIMO-OFDM system can compensate for the lacks of MIMO systems and give play to the advantages of OFDM system. In this paper, a general Quasi orthogonal space time block code (QOSTBC) structure is proposed for multiple-input multiple-output–orthogonal frequency-division multiplexing (MIMO-OFDM) systems for 4X4 antenna configuration. The signal detection technology used in this paper for MIMO-OFDM system is Zero-Forcing Equalization (linear detection technique). In this paper the analysis of high level of modulations (i.e. M-PSK for different values of M) on MIMO-OFDM system is presented. Here AWGN and Rayleigh channels have been used for analysis purpose and their effect on BER for high data rates have been presented. The proposed MIMO-OFDM system with QOSTBC using 4X4 antenna configuration has better performance in terms of BER vs SNR than the other systems.
Capacity Enhancement of MIMO-OFDM System in Rayleigh Fading ChannelIOSR Journals
MIMO-OFDM system in Rayleigh Fading Channel is very popular technique for mobile
communication now a day’s for research. Here we want increase the capacity of MIMO-OFDM of system by
using adaptive modulation, Algebraic Space-Time Codes (ASTC) encoder for MIMO Systems are based on
quaternion algebras .we found that ergodic capacity has some limitation which reduce the system’s
performance to overcome this we use ASTC code . ASTC code are full rank, full rate and non vanishing constant
minimum determinant for increasing spectral efficiency and reducing Peak to Average Power Ratio (PAPR) .
Performance evaluation on the basis of bit error rate for different order of ...ijmnct
Today, we have required to accommodate a large number of users under a single base station. This can be
possible only if we have some flexibility over the spectrum. Previously we have lots of multiplexing methods
to accommodate large number of signals in time and frequency domain. But now we have required to
accommodate a large number of users in the same bandwidth, without any fading over the received signal.
So, orthogonality can be maintained over the frequency response. This technology is now more popular in
the mobile communication domain, called Orthogonal Frequency Division Multiplexing (OFDM). Actually
user data can be converted into the parallel form and then they are modulated using digital modulation
techniques. Finally, they have followed by OFDM Modulator and cyclic prefix can be inserted into the
OFDM symbols. Here, I have worked on the measurement of Bit error rate for different modulation
techniques in OFDM technology. It has been considered that subchannel size is not constant. According to
that I have concluded the overall idea regarding the performance under OFDM technology.
Performance Analysis of MIMO-OFDM System Using QOSTBC Code Structure for M-PSKCSCJournals
MIMO-OFDM system has been currently recognized as one of the most competitive technology for 4G mobile wireless systems. MIMO-OFDM system can compensate for the lacks of MIMO systems and give play to the advantages of OFDM system. In this paper, a general Quasi orthogonal space time block code (QOSTBC) structure is proposed for multiple-input multiple-output–orthogonal frequency-division multiplexing (MIMO-OFDM) systems for 4X4 antenna configuration. The signal detection technology used in this paper for MIMO-OFDM system is Zero-Forcing Equalization (linear detection technique). In this paper the analysis of high level of modulations (i.e. M-PSK for different values of M) on MIMO-OFDM system is presented. Here AWGN and Rayleigh channels have been used for analysis purpose and their effect on BER for high data rates have been presented. The proposed MIMO-OFDM system with QOSTBC using 4X4 antenna configuration has better performance in terms of BER vs SNR than the other systems.
Capacity Enhancement of MIMO-OFDM System in Rayleigh Fading ChannelIOSR Journals
MIMO-OFDM system in Rayleigh Fading Channel is very popular technique for mobile
communication now a day’s for research. Here we want increase the capacity of MIMO-OFDM of system by
using adaptive modulation, Algebraic Space-Time Codes (ASTC) encoder for MIMO Systems are based on
quaternion algebras .we found that ergodic capacity has some limitation which reduce the system’s
performance to overcome this we use ASTC code . ASTC code are full rank, full rate and non vanishing constant
minimum determinant for increasing spectral efficiency and reducing Peak to Average Power Ratio (PAPR) .
Performance evaluation on the basis of bit error rate for different order of ...ijmnct
Today, we have required to accommodate a large number of users under a single base station. This can be
possible only if we have some flexibility over the spectrum. Previously we have lots of multiplexing methods
to accommodate large number of signals in time and frequency domain. But now we have required to
accommodate a large number of users in the same bandwidth, without any fading over the received signal.
So, orthogonality can be maintained over the frequency response. This technology is now more popular in
the mobile communication domain, called Orthogonal Frequency Division Multiplexing (OFDM). Actually
user data can be converted into the parallel form and then they are modulated using digital modulation
techniques. Finally, they have followed by OFDM Modulator and cyclic prefix can be inserted into the
OFDM symbols. Here, I have worked on the measurement of Bit error rate for different modulation
techniques in OFDM technology. It has been considered that subchannel size is not constant. According to
that I have concluded the overall idea regarding the performance under OFDM technology.
Analyses and performance of techniques papr reduction for stbc mimo ofdm syst...ijwmn
An OFDM system is combined with multiple-input mult
iple-output (MIMO) in order to increase the
diversity gain and system capacity over the time va
riant frequency-selective channels. However, a maj
or
drawback of MIMO-OFDM system is that the transmitte
d signals on different antennas might exhibit high
peak-to-average power ratio (PAPR).In this paper, w
e present a PAPR analysis reduction of space-time-
block-coded (STBC) MIMO-OFDM system for 4G wireless
networks. Several techniques have been used to
reduce the PAPR of the (STBC) MIMOOFDM system: clip
ping and filtering, partial transmit sequence
(PTS) and selected mapping (SLM). Simulation result
s show that clipping and filtering provides a bette
r
PAPR reduction than the others methods and only SLM
technique conserve the PAPR reduction in
reception part of signal.
Performance and Analysis of OFDM Signal Using Matlab SimulinkIJMER
Multi-carrier modulation is an attractive technique for fourth generation .OFDM is based on
multicarrier modulation technique. In OFDM system the bit stream is divided into many different sub
channels. An efficient and distortionless scheme for peak power reduction in OFDM is proposed. In this
paper, a set of mapping where the actual transmit signal is selected. From this set of signal reduced
PAPR. Simulation results are shown. The lowest PAPR is compared with conventional work. It is also
compared BER to SNR and best result is achieved.
Performance Analysis of 802.lln MIMO OFDM TransceiverIJERA Editor
The increasing demand on real time application to achieve high throughput, reliable wireless system and network capacity for fourth generation wireless local area networks is to combine MIMO wireless technology with OFDM. Orthogonal Frequency Division Multiplexing (OFDM), which offers reliable high bit rate wireless system with reasonable low complexity. OFDM does provide large data rates with sufficient robustness to radio channel impairments. OFDM is a combination of modulation and multiplexing and are able to maximize spectral efficiency without causing adjacent channel interference. This paper first focuses on 802.11n standard, MIMO-OFDM system. This paper further reviews different work done on implementation of MIMO-OFDM transceiver for 802.11n standard.
5GHz MIMO System Power Amplifier design with Adaptive Feedforward Linearizati...Ahmed Nasser Agag
- In such transceiver system, we used power amplifier stage in transmitter section and polyphase filter (PPF) in local oscillator (LO) section
- Less linearity of power amplifier causes higher order intermodulation and consequently destroys orthogonality between subcarriers in OFDM signals.
- Phase error in quadrature LO signal causes crosstalk between I and Q signals and results unavoidable demodulation errors.
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.
Implementation of 8x8 MIMO OFDM systems for higher order modulation using QOS...ijsrd.com
A general Quasi orthogonal space time block code (QOSTBC) structure is proposed for multiple-input multiple-output-orthogonal frequency division multiplexing (MIMO-OFDM) systems for 8 X 8 antenna configuration. The signal detection technology used in this work for MIMO-OFDM system is Zero-Forcing Equalization (linear detection technique). In this paper, analysis of high level of modulations (i.e. M-QAM and M-PSK for different values of M) on MIMO-OFDM system is presented. In this, AWGN, Rayleigh and Rician channels have been used for analysis purpose and their effect on BER and Spectral Efficiency for high data rates have been presented. The proposed system has better performance than the other systems in terms of SNR improvement of 3-5 dB and spectral efficiency.
SLM-PTS BASED PAPR REDUCTION TECHNIQUES IN OFDM SYSTEMHariniChaganti1
Signals, which were initially sent in the analog domain, are being sent more and more in the digital domain these days. For better transmission, even single–carrier waves are being replaced by multi–carriers. Multi-carrier
systems like OFDM are now – a – days being implemented commonly. In the OFDM system,
orthogonally placed subcarriers are used to carry the data from the transmitter end to the receiver end. The presence of a guard band in this system deals with the problem of ISI and noise is minimized by a larger number of sub–carriers. But the large Peak– to –Average Power Ratio of these signal have some undesirable effects on the system. The Peak-to-Average Power Ratio is the ratio between the maximum power and average power of a complex passband signal. It causes many disadvantages like band-in and band-out variation, low signal to quantization noise ratio, low efficiency of power amplifier, etc. Hence, it is necessary to reduce PAPR in OFDM for its efficient use.
In this project, the main objective is to study the basics of an OFDM System and analyze and
simulate various methods such as clipping and filtering, selected mapping, Partial transmit sequence
to reduce the PAPR in the system and compare these techniques with and without PAPR reduction to
obtain an efficient technique so that this system can be used more commonly and effectively.
Hybrid PAPR Reduction Scheme for Universal Filter Multi-Carrier Modulation in...CrimsonPublishersRDMS
Hybrid PAPR Reduction Scheme for Universal Filter Multi-Carrier Modulation in Next Generation Wireless Systems by Himanshu Monga* in Crimson Publishers: Peer Reviewed Material Science Journals
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
Index modulation is one of the promising techniques for future communications systems due to many improvement over the classical orthogonal frequency division multiplexing systems such as single RF chain, increased throughput for the same modulation order, achieved tradeoff between the efficiencies of the power and the spectral, and elimination of inter-channel interference. Many forms of index modulation researches exist where symbols are conveyed in antennas, subcarriers, time slots, and the space-time matrix. Spatial modulation is one member of index modulation family where symbols are conveyed in activating transmit/receive antennas. In this paper, a modification to a standard multiple input single output scheme by integrating spatial modulation using simplified mathematical procedure is achieved. In the transmitter side, data and activation symbols are distributed simultaneously using mathematical module and floor functions. At the receiver, a simplified maximum likelihood detector is used to obtain transmitted pair of symbols. To verify this, MATLAB simulink is used to simulate a downlink system where spatial modulation is applied to a base station. Results for different transmit antenna number and modulation order are obtained in the form of bit error rate versus signal to noise ratio.
Designing and Performance Evaluation of 64 QAM OFDM SystemIOSR Journals
Abstract (11Bold) : — In this report, the performance analysis of 64 QAM-OFDM wireless communication
systems affected by AWGN in terms of Symbol Error Rate and Throughput is addressed. 64 QAM (64 ary
Quadrature Amplitude Modulation) is the one of the effective digital modulation technique as it is more power
efficient for larger values of M(64). The MATLAB script based model of the 64 QAM-OFDM system with
normal AWGN channel and Rayleigh fading channel has been made for study error performance and
throughput under different channel conditions. This simulated model maximizes the system throughput in the
presence of narrowband interference, while guaranteeing a SER below a predefined threshold. The SER
calculation is accomplished by means of modelling the decision variable at the receiver as a particular case of
quadratic form D in complex Gaussian random variables. Lastly comparative study of SER performance of 64
QAM-OFDM simulated & 64 QAM-OFDM theoretical under AWGN channel has been given. Also
performance of the system is given in terms of throughput (received bits/ofm symbol) is given in a plot for
different SNR. Keywords (11Bold) –64 QAM, BPSK, OFDM, PDF, SNR.
Analyses and performance of techniques papr reduction for stbc mimo ofdm syst...ijwmn
An OFDM system is combined with multiple-input mult
iple-output (MIMO) in order to increase the
diversity gain and system capacity over the time va
riant frequency-selective channels. However, a maj
or
drawback of MIMO-OFDM system is that the transmitte
d signals on different antennas might exhibit high
peak-to-average power ratio (PAPR).In this paper, w
e present a PAPR analysis reduction of space-time-
block-coded (STBC) MIMO-OFDM system for 4G wireless
networks. Several techniques have been used to
reduce the PAPR of the (STBC) MIMOOFDM system: clip
ping and filtering, partial transmit sequence
(PTS) and selected mapping (SLM). Simulation result
s show that clipping and filtering provides a bette
r
PAPR reduction than the others methods and only SLM
technique conserve the PAPR reduction in
reception part of signal.
Performance and Analysis of OFDM Signal Using Matlab SimulinkIJMER
Multi-carrier modulation is an attractive technique for fourth generation .OFDM is based on
multicarrier modulation technique. In OFDM system the bit stream is divided into many different sub
channels. An efficient and distortionless scheme for peak power reduction in OFDM is proposed. In this
paper, a set of mapping where the actual transmit signal is selected. From this set of signal reduced
PAPR. Simulation results are shown. The lowest PAPR is compared with conventional work. It is also
compared BER to SNR and best result is achieved.
Performance Analysis of 802.lln MIMO OFDM TransceiverIJERA Editor
The increasing demand on real time application to achieve high throughput, reliable wireless system and network capacity for fourth generation wireless local area networks is to combine MIMO wireless technology with OFDM. Orthogonal Frequency Division Multiplexing (OFDM), which offers reliable high bit rate wireless system with reasonable low complexity. OFDM does provide large data rates with sufficient robustness to radio channel impairments. OFDM is a combination of modulation and multiplexing and are able to maximize spectral efficiency without causing adjacent channel interference. This paper first focuses on 802.11n standard, MIMO-OFDM system. This paper further reviews different work done on implementation of MIMO-OFDM transceiver for 802.11n standard.
5GHz MIMO System Power Amplifier design with Adaptive Feedforward Linearizati...Ahmed Nasser Agag
- In such transceiver system, we used power amplifier stage in transmitter section and polyphase filter (PPF) in local oscillator (LO) section
- Less linearity of power amplifier causes higher order intermodulation and consequently destroys orthogonality between subcarriers in OFDM signals.
- Phase error in quadrature LO signal causes crosstalk between I and Q signals and results unavoidable demodulation errors.
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.
Implementation of 8x8 MIMO OFDM systems for higher order modulation using QOS...ijsrd.com
A general Quasi orthogonal space time block code (QOSTBC) structure is proposed for multiple-input multiple-output-orthogonal frequency division multiplexing (MIMO-OFDM) systems for 8 X 8 antenna configuration. The signal detection technology used in this work for MIMO-OFDM system is Zero-Forcing Equalization (linear detection technique). In this paper, analysis of high level of modulations (i.e. M-QAM and M-PSK for different values of M) on MIMO-OFDM system is presented. In this, AWGN, Rayleigh and Rician channels have been used for analysis purpose and their effect on BER and Spectral Efficiency for high data rates have been presented. The proposed system has better performance than the other systems in terms of SNR improvement of 3-5 dB and spectral efficiency.
SLM-PTS BASED PAPR REDUCTION TECHNIQUES IN OFDM SYSTEMHariniChaganti1
Signals, which were initially sent in the analog domain, are being sent more and more in the digital domain these days. For better transmission, even single–carrier waves are being replaced by multi–carriers. Multi-carrier
systems like OFDM are now – a – days being implemented commonly. In the OFDM system,
orthogonally placed subcarriers are used to carry the data from the transmitter end to the receiver end. The presence of a guard band in this system deals with the problem of ISI and noise is minimized by a larger number of sub–carriers. But the large Peak– to –Average Power Ratio of these signal have some undesirable effects on the system. The Peak-to-Average Power Ratio is the ratio between the maximum power and average power of a complex passband signal. It causes many disadvantages like band-in and band-out variation, low signal to quantization noise ratio, low efficiency of power amplifier, etc. Hence, it is necessary to reduce PAPR in OFDM for its efficient use.
In this project, the main objective is to study the basics of an OFDM System and analyze and
simulate various methods such as clipping and filtering, selected mapping, Partial transmit sequence
to reduce the PAPR in the system and compare these techniques with and without PAPR reduction to
obtain an efficient technique so that this system can be used more commonly and effectively.
Hybrid PAPR Reduction Scheme for Universal Filter Multi-Carrier Modulation in...CrimsonPublishersRDMS
Hybrid PAPR Reduction Scheme for Universal Filter Multi-Carrier Modulation in Next Generation Wireless Systems by Himanshu Monga* in Crimson Publishers: Peer Reviewed Material Science Journals
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
Index modulation is one of the promising techniques for future communications systems due to many improvement over the classical orthogonal frequency division multiplexing systems such as single RF chain, increased throughput for the same modulation order, achieved tradeoff between the efficiencies of the power and the spectral, and elimination of inter-channel interference. Many forms of index modulation researches exist where symbols are conveyed in antennas, subcarriers, time slots, and the space-time matrix. Spatial modulation is one member of index modulation family where symbols are conveyed in activating transmit/receive antennas. In this paper, a modification to a standard multiple input single output scheme by integrating spatial modulation using simplified mathematical procedure is achieved. In the transmitter side, data and activation symbols are distributed simultaneously using mathematical module and floor functions. At the receiver, a simplified maximum likelihood detector is used to obtain transmitted pair of symbols. To verify this, MATLAB simulink is used to simulate a downlink system where spatial modulation is applied to a base station. Results for different transmit antenna number and modulation order are obtained in the form of bit error rate versus signal to noise ratio.
Designing and Performance Evaluation of 64 QAM OFDM SystemIOSR Journals
Abstract (11Bold) : — In this report, the performance analysis of 64 QAM-OFDM wireless communication
systems affected by AWGN in terms of Symbol Error Rate and Throughput is addressed. 64 QAM (64 ary
Quadrature Amplitude Modulation) is the one of the effective digital modulation technique as it is more power
efficient for larger values of M(64). The MATLAB script based model of the 64 QAM-OFDM system with
normal AWGN channel and Rayleigh fading channel has been made for study error performance and
throughput under different channel conditions. This simulated model maximizes the system throughput in the
presence of narrowband interference, while guaranteeing a SER below a predefined threshold. The SER
calculation is accomplished by means of modelling the decision variable at the receiver as a particular case of
quadratic form D in complex Gaussian random variables. Lastly comparative study of SER performance of 64
QAM-OFDM simulated & 64 QAM-OFDM theoretical under AWGN channel has been given. Also
performance of the system is given in terms of throughput (received bits/ofm symbol) is given in a plot for
different SNR. Keywords (11Bold) –64 QAM, BPSK, OFDM, PDF, SNR.
Designing and Performance Evaluation of 64 QAM OFDM SystemIOSR Journals
In this report, the performance analysis of 64 QAM-OFDM wireless communication
systems affected by AWGN in terms of Symbol Error Rate and Throughput is addressed. 64 QAM (64 ary
Quadrature Amplitude Modulation) is the one of the effective digital modulation technique as it is more power
efficient for larger values of M(64). The MATLAB script based model of the 64 QAM-OFDM system with
normal AWGN channel and Rayleigh fading channel has been made for study error performance and
throughput under different channel conditions. This simulated model maximizes the system throughput in the
presence of narrowband interference, while guaranteeing a SER below a predefined threshold. The SER
calculation is accomplished by means of modelling the decision variable at the receiver as a particular case of
quadratic form D in complex Gaussian random variables. Lastly comparative study of SER performance of 64
QAM-OFDM simulated & 64 QAM-OFDM theoretical under AWGN channel has been given. Also
performance of the system is given in terms of throughput (received bits/ofm symbol) is given in a plot for
different SNR
In this paper, Space Time Block Code (STBC), Spatial Multiplexing (SM) and hybrid model with OFDM
are designed for Rayleigh fading channel. Combination of SM and STBC forms hybrid MIMO model. The
performances of the above mentioned models with different modulations such as Quadrature Phase Shift
Keying (QPSK) and Quadrature Amplitude Modulation (QAM) with multiple antennas are measured with
respect to BER. In this paper, it is shown that Hybrid MIMO provides low BER. Thus, in wireless
communication, hybrid model improves the data rate and link reliability.
A Carrierless Amplitude Phase (CAP) Modulation Format: Perspective and Prospe...IJECEIAES
The explosive demand of broadband services nowadays requires data communication systems to have intensive capacity which subsequently increases the need for higher data rate as well. Although implementation of multiple wavelengths channels can be used (e.g. 4 × 25.8 Gb/s for 100 Gb/s connection) for such desired system, it usually leads to cost increment issue which is caused by employment of multiple optical components. Therefore, implementation of advanced modulation format using a single wavelength channel has become a preference to increase spectral efficiency by increasing the data rate for a given transmission system bandwidth. Conventional advanced modulation format however, involves a degree of complexity and costly transmission system. Hence, carrierless amplitude phase (CAP) modulation format has emerged as a promising advanced modulation format candidate due to spectral efficiency improvement ability with reduction of optical transceiver complexity and cost. The intriguing properties of CAP modulation format are reviewed as an attractive prospect in optical transmission system applications.
Capsulization of Existing Space Time TechniquesIJEEE
In this paper, we explore the fundamental
concepts behind the emerging field of space-time coding for
wireless communication system. A space–time code (STC)
is a method which employed to increase the reliability of
data transmission in the wireless communication
systems using multiple transmit antennas.
PERFORMANCE ANALYSIS OF QOS PARAMETERS LIKE PSNR, MAE & RMSE USED IN IMAGE TR...Journal For Research
Wireless designers constantly seek to improve the spectrum efficiency/capacity, coverage of wireless networks and link reliability. In this direction, Space-time wireless technology that uses multiple antennas along with appropriate signaling and receiver techniques that offers a powerful tool for improving the wireless performance is used in this thesis work. A special version of STBC called ‘Alamouti code’ is used. PSK modulation scheme is used for modulation of data. In this thesis work, the Space-Time Block Codes (STBC) is used in WLAN wireless network that uses multiple numbers of antennas at both transmitter and receiver. The STBC which includes the Alamouti Scheme for 2 transmit antenna and a different number of receiving antenna has been studied, simulated and analyzed. The simulation has been done in MATLAB. Throughput and several parameter performance has been analyzed using the MATLAB.A sample image is transmitted to compare the performance of various parameters like RMSE, PSNR, MAE etc. All the parameters are plotted against SNR (in dB) values ranging from -18 to 30. Various observations being made for the improvement in various parameters with increasing SNR and/or with changing diversity scheme. AWGN channel is used here for communication of sampled image data.
PERFORMANCE EVALUATION OF MC-CDMA SYSTEM OVER RAYLEIGH FADING CHANNELIJCSES Journal
Multi Carrier Code Division Multiple Access (MC-CDMA) is a well known technique for high speed
wireless data transmission .Two advanced technology was included in the MC-CDMA structure, such as
orthogonal frequency division multiplex (OFDM) and the code division multiple access (CDMA),so that it
benefits from the robustness of OFDM against multipath environment and from the capability of multiuser
multiplexing services that is achieved via (CDMA) system. MC-CDMA is a multicarrier spread spectrum
system which is classified as the candidate scheme for future mobile radio systems. In this paper MCCDMA
system, with Rayleigh fading channel and 16QAM array modulation, was simulated to investigate
the effects of different parameters on the system performance, such as processing gain; number of paths;
number of users; interleaving; and coding ratio.MC-CDMA performances can be considerably improved
by proper selection of these parameters. As expected, results show that MC-CDMA has a better performance over CDMA system.
Channel Estimation Techniques in MIMO-OFDM LTE SystemsCauses and Effects of C...IJERA Editor
There is an increasing demand for high data transmission rates with the evolution of the very large scale integration (VLSI) technology. The multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) systems are used to fulfill these requirements because of their unique properties such as high spectral efficiency, high data rate and resistance towards multipath propagation. MIMO-OFDM systems are finding their applications in the modern wireless communication systems like IEEE 802.11n, 4G and LTE. They also offer reliable communication with the increased coverage area. The bottleneck to the MIMO-OFDM systems is the estimation of the channel state information (CSI). This can be estimated with the help of any one of the Training Based, Semiblind and Blind Channel estimation algorithms. This paper presents various channel estimation algorithms, optimization techniques and their effective utilization in MIMO-OFDM for modern wireless LTE systems.
Performance Analysis of Post Compensated Long Haul High Speed Coherent Optica...IJECEIAES
This paper addresses the performance analysis of OFDM transmission system based on coherent detection over high speed long haul optical links with high spectral efficiency modulation formats such as Quadrature Amplitude Modulation (QAM) as a mapping method prior to the OFDM multicarrier representation. Post compensation is used to compensate for phase noise effects. Coherent detection for signal transmitted at bit rate of 40 Gbps is successfully achieved up to distance of 3200km. Performance is analyzed in terms of Symbol Error Rate and Error Vector Magnitude by varying Optical Signal to Noise Ratio (OSNR) and varying the length of the fiber i.e transmission distance. Transmission performance is also observed through constellation diagrams at different transmission distances and different OSNRs.
Performance Analysis of Post Compensated Long Haul High Speed Coherent Optica...Yayah Zakaria
This paper addresses the performance analysis of OFDM transmission system based on coherent detection over high speed long haul optical links with high spectral efficiency modulation formats such as Quadrature Amplitude Modulation (QAM) as a mapping method prior to the OFDM multicarrier representation. Post compensation is used to compensate for
phase noise effects. Coherent detection for signal transmitted at bit rate of 40 Gbps is successfully achieved up to distance of 3200km. Performance is analyzed in terms of Symbol Error Rate and Error Vector Magnitude by varying Optical Signal to Noise Ratio (OSNR) and varying the length of the fiber i.e transmission distance. Transmission performance is also observed through constellation diagrams at different transmission distances and
different OSNRs.
Combining SFBC_OFDM Systems with SVD Assisted Multiuser Transmitter and Multi...IOSR Journals
Abstract: In this work, we exploit the SVD assisted multiuser transmitter (MUT) and multiuser detector (MUD) technique, using downlink (DL) preprocessing transmitter and DL postprocessing receiver matrice .In combination with space frequency block coding (SFBC). And also propose the precoded DL transmission scheme, were the both proposed schemes take advantage of the channel state information (CSI) of all users at the base station (BS), but only of the mobile station (MS)’s own CSI, to decompose the MU MIMO channels into parallel single input single output (SISO), these two proposed schemes are compared to the vertical layered space time (V_BLAST) combined with SFBC (SFBC_VBLAST). Our Simulation results show that the performance of the proposed scheme with DL Zero Forcing (ZF) transmitter for interference canceller outperforms the SFBC_VBLAST and the precoded DL schemes with ZF receiver in frequency selective fading channels. Keywords – Post processing, Preprocessing,, SFBC, SVD, ZF.
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.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
A Novel Alamouti STBC Technique for MIMO System Using 16- QAM Modulation and ...IJERA Editor
The wireless communication is the emerging field of research among communication researchers and they are
continuously working towards the reduction if error occurred in the signal during transmission through wireless
media. In this paper the wireless system is simulated with the application of Alamouti space time block codes
(STBC) with MIMO and MISO configurations to compare the results. The modulation technique used here is
16-QAM which is giving better results than other counterparts and to enhance the performance of the system i.e.
to reduce the effect of errors on data we have applied a moving average filter(MAF). The performance of the
system is shown with the simulation results with variable data sizes and found that the proposed approach is
better for the system.
Implementation of High Speed OFDM Transceiver using FPGAMangaiK4
Abstract - Proficient, multi mode and re-configurable architecture of interleaver/de-interleaver for multiple standards, like DVB, OFDM and WLAN is presented. Interleaver plays vital role in 4G technologies to recover symbols from burst errors. The aim of our work is to design a reconfigurable modulation technique called Adaptive modulation scheme uses QAM, QPSK and BPSK modulation that adapt themselves based on channel Signal to Noise ratio. Subcarrier allocation algorithm specifically used to focus on utilizing channels with high gains. Our proposed model can achieves a data rate of min 2.5 Gbps as per 3GPP standard by adaptive modulation technique using QAM, BPSK and QPSK.
Similar to Iaetsd stbc-ofdm downlink baseband receiver for mobile wman (20)
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
Hierarchical Digital Twin of a Naval Power SystemKerry Sado
A hierarchical digital twin of a Naval DC power system has been developed and experimentally verified. Similar to other state-of-the-art digital twins, this technology creates a digital replica of the physical system executed in real-time or faster, which can modify hardware controls. However, its advantage stems from distributing computational efforts by utilizing a hierarchical structure composed of lower-level digital twin blocks and a higher-level system digital twin. Each digital twin block is associated with a physical subsystem of the hardware and communicates with a singular system digital twin, which creates a system-level response. By extracting information from each level of the hierarchy, power system controls of the hardware were reconfigured autonomously. This hierarchical digital twin development offers several advantages over other digital twins, particularly in the field of naval power systems. The hierarchical structure allows for greater computational efficiency and scalability while the ability to autonomously reconfigure hardware controls offers increased flexibility and responsiveness. The hierarchical decomposition and models utilized were well aligned with the physical twin, as indicated by the maximum deviations between the developed digital twin hierarchy and the hardware.
NO1 Uk best vashikaran specialist in delhi vashikaran baba near me online vas...Amil Baba Dawood bangali
Contact with Dawood Bhai Just call on +92322-6382012 and we'll help you. We'll solve all your problems within 12 to 24 hours and with 101% guarantee and with astrology systematic. If you want to take any personal or professional advice then also you can call us on +92322-6382012 , ONLINE LOVE PROBLEM & Other all types of Daily Life Problem's.Then CALL or WHATSAPP us on +92322-6382012 and Get all these problems solutions here by Amil Baba DAWOOD BANGALI
#vashikaranspecialist #astrologer #palmistry #amliyaat #taweez #manpasandshadi #horoscope #spiritual #lovelife #lovespell #marriagespell#aamilbabainpakistan #amilbabainkarachi #powerfullblackmagicspell #kalajadumantarspecialist #realamilbaba #AmilbabainPakistan #astrologerincanada #astrologerindubai #lovespellsmaster #kalajaduspecialist #lovespellsthatwork #aamilbabainlahore#blackmagicformarriage #aamilbaba #kalajadu #kalailam #taweez #wazifaexpert #jadumantar #vashikaranspecialist #astrologer #palmistry #amliyaat #taweez #manpasandshadi #horoscope #spiritual #lovelife #lovespell #marriagespell#aamilbabainpakistan #amilbabainkarachi #powerfullblackmagicspell #kalajadumantarspecialist #realamilbaba #AmilbabainPakistan #astrologerincanada #astrologerindubai #lovespellsmaster #kalajaduspecialist #lovespellsthatwork #aamilbabainlahore #blackmagicforlove #blackmagicformarriage #aamilbaba #kalajadu #kalailam #taweez #wazifaexpert #jadumantar #vashikaranspecialist #astrologer #palmistry #amliyaat #taweez #manpasandshadi #horoscope #spiritual #lovelife #lovespell #marriagespell#aamilbabainpakistan #amilbabainkarachi #powerfullblackmagicspell #kalajadumantarspecialist #realamilbaba #AmilbabainPakistan #astrologerincanada #astrologerindubai #lovespellsmaster #kalajaduspecialist #lovespellsthatwork #aamilbabainlahore #Amilbabainuk #amilbabainspain #amilbabaindubai #Amilbabainnorway #amilbabainkrachi #amilbabainlahore #amilbabaingujranwalan #amilbabainislamabad
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
Iaetsd stbc-ofdm downlink baseband receiver for mobile wman
1. Abstract:This paper proposes a space time block code-
orthogonalfrequency division multiplexing downlink
baseband receiverformobile wirelessmetropolitan area
network. The proposed basebandreceiver applied in the
system with two transmit antennasand one receive antenna
aims to provide high performance in outdoormobile
environments. It provides a simple and robust
synchronizerand an accurate but hardware affordable
channel estimatorto overcome the challenge of multipath
fading channels.The coded bit error rate performance for 16
quadrature amplitudemodulation can achieve less than10-
6
under the vehicle speedof 120 km/hr. The proposed
baseband receiver designed in 90-nmCMOS technology can
support up to 27.32 Mb/s un-coded datatransmission under
10MHz channel bandwidth. It requires a corearea of
2.41×2.41mm2
and dissipates 68.48 mW at 78.4 MHzwith 1
V power supply.
Index Terms:Baseband receiver, channel estimator,
spacetime block code-orthogonal frequency division
multiplexing(STBC-OFDM) system, synchronizer, wireless
metropolitanarea network (WMAN)
I. INTRODUCTION
Multiple Input Multiple Output Orthogonal Frequency
Division Multiplexing (MIMO-OFDM) techniques have
been recently considered in the panorama of ongoing and
future multimedia mobile communications due to their
robustness to frequency-selective fading and their flexibility
in handling multiple data rates. Nowadays, MIMO-OFDM
techniques present some well-promising applications in
wireless standards like IEEE 802.11n, E-UTRAN Long
Term Evolution (LTE), and IEEE 802.16x (Wi-Max) [2].
Different Space-Time (ST) processing techniques have been
proposed in the literature in order to fully exploit the
potentialities of MIMO systems. The most popular one is
Space-Time Coding in which the time dimension is
complemented with the spatial dimension inherent to the use
of multiple spatially-distributed antennas. Commonly used
ST coding schemes are ST-trellis codes and ST block codes
(STBC). A well-known example of conceptually simple,
computationally efficient and mathematically elegant STBC
scheme has been proposed by Alamouti. Substantially,
Alamouti’s coding is an orthogonal ST block code where
two successive symbols are encoded in an orthogonal 2x2
matrix. The columns of the matrix are transmitted in
successive symbol periods, but the upper and the lower
symbols in a given column are sent simultaneously through
the first and the second transmit antennas, respectively.
The alternative solution to ST coding is represented by
Spatial Multiplexing (SM). Spatial multiplexing is a space-
time modulation technique whose core idea is to send
independent data streams from each transmit antenna. This
is motivated by the spatially white property of the
distribution which achieves capacity in MIMO i.e. Rayleigh
matrix channels. SM is addressed to push up link capacity
rather than to exploit spatial diversity. The tradeoff is
between spatial diversity exploitation (STBC) and capacity
boosting (SM). Such tradeoff has been theoretically studied
by Heath and Paulraj and some simulation results have been
shown for a switch criterion from STBC to SM (and vice-
versa) based on the minimum Euclidean distance of the
received codebook. Recent contributions presented in
literature are aimed at proposing practical solutions for
MIMO-OFDM ST processing to be specifically applied in
the framework of on-going wireless standards. Bian et. al.
considered a range of MIMO-OFDM architectures for use in
urban hotspots in the framework of IEEE 802.11n. Link
adaptation drives the choice of the space-time signal
processing. In the urban areas tested 2% of the covered
locations selected the SM scheme, 50% selected the STBC
scheme, and 48% selected a hybrid SM/STBC scheme. The
combination of SM and adaptive beam forming in MIMO-
OFDM systems for IEEE 802.16e WMAN standard has
been studied by Chung, Yung and Choi , Aruna and
Suganthi proposed a variable power adaptive MIMO-
OFDMSTBC for Wi-Max in order to provide flexible data-
rate services while satisfying low delay requirements in the
presence of imperfect CSI knowledge.
Motivation
An efficient solution from a computational viewpoint is
presented. The architecture is designed by considering a cost
function based on the execution time and the FPGA
resources parameters. Finding a suitable solution is a matter
of trading off these two parameters. The proposed solution
exploits the maximum operation parallelism in order to
reduce the execution time. On the other hand, to minimize
the number of required resources, basic real operators are
used, such as multipliers, adders, and CORDIC dividers.
Moreover, the use of integrated processors and high
accuracy operators is avoided to preserve the initial trade-
off.
The inputs of the system are the received signal matrix Y
and the estimated channel matrix H. All the signals are
complex variables, so real operators must be combined to
perform this operation. This is done minimizing the number
STBC-OFDM Downlink Baseband Receiver for Mobile WMAN
Ari Vamsi1
, Tulasi Sanath Kumar2
1
PG Student, Department of Electronics & Communication Engineering, ASCET, Gudur, A.P, India.
2
Asst. Professor, Department of Electronics & Communication Engineering, ASCET, Gudur, A.P, India
1
ari.vamsi@gmail.com
2
tulasisanath@gmail.com
Proceedings of International Conference on Advances in Engineering and Technology
www.iaetsd.in
ISBN : 978 - 1505606395
International Association of Engineering and Technology for Skill Development
64
2. of operators, such as avoiding complex divisions (which
would need a large amount of resources), replacing them
with complex multiplications followed by real divisions.
Fig.1 shows the evolution of current services and networks
to the aim of combining them into a unified third generation
network. Many currently separate systems and services
such as radio paging, cordless telephony, satellite phones
and private radio systems for companies etc will be
combined so that all these services will be provided by third
generation telecommunications systems the parallel
operators which compute the decoding operation with the
coefficients α and β. The final outputs are the interference-
free decoded OFDM symbols obtained by solving the linear
system but extended for the 4x4 case. In order to evaluate
the implementation of the subtractive 4x4 OFDM-MIMO
combiner considered in this paper, a Xilinx Spartan FPGA
has been used. For the specification, synthesis, and
implementation, System Generator and Xilinx ISE have
been used.
Fig.1. Evolution of current networks to the next generation
of wireless networks
This paper is organized as follows. Section II OFDM
Generation.Space-Time Block Codingin Section III .Section
IV Architecture and Circuit Design.Then, the simulation and
implementation results is provided in Section V. Finally,
Section VI is the conclusions.
II. OFDM GENERATION
To generate OFDM successfully the relationship between all
the carriers must be carefully controlled to maintain the
Orthogonality of the carriers. For this reason, OFDM is
generated by firstly choosing the spectrum required, based
on the input data, and modulation scheme used. Each carrier
to be produced is assigned some data to transmit. The
required amplitude and phase of the carrier is then
calculated based on the modulation scheme (typically
differential BPSK, QPSK, or QAM).
The required spectrum is then converted back to its time
domain signal using an Inverse Fourier Transform. In most
applications, an Inverse Fast Fourier Transform (IFFT) is
used. The IFFT performs the transformation very efficiently,
and provides a simple way of ensuring the carrier signals
produced are orthogonal.
The Fast Fourier Transform (FFT) transforms a cyclic time
domain signal into its equivalent frequency spectrum. This
is done by finding the equivalent waveform, generated by a
sum of orthogonal sinusoidal components. The amplitude
and phase of the sinusoidal components represent the
frequency spectrum of the time domain signal.
The IFFT performs the reverse process, transforming a
spectrum (amplitude and phase of each component) into a
time domain signal. An IFFT converts a number of complex
data points, of length, which is a power of 2, into the time
domain signal of the same number of points. Each data point
in frequency spectrum used for an FFT or IFFT is called a
bin. The orthogonal carriers required for the OFDM signal
can be easily generated by setting the amplitude and phase
of each bin, then performing the IFFT. Since each bin of an
IFFT corresponds to the amplitude and phase of a set of
orthogonal sinusoids, the reverse process guarantees that the
carriers generated are orthogonal.
Fig. 2 OFDM Block Diagram
Fig. 2 shows the setup for a basic OFDM transmitter and
receiver. The signal generated is a base band, thus the signal
is filtered, then stepped up in frequency before transmitting
the signal. OFDM time domain waveforms are chosen such
that mutual Orthogonality is ensured even though sub-
carrier spectra may overlap. Typically QAM or Differential
Quadrature Phase Shift Keying (DQPSK) modulation
schemes are applied to the individual sub carriers. To
prevent ISI, the individual blocks are separated by guard
intervals wherein the blocks are periodically extended.
III. SPACE-TIME BLOCK CODING
Multiple-input multiple-output (MIMO) system is known to
exploit the antenna diversity to develop the performances of
wireless communication systems using multiple antenna
elements at the transmitter and receiver ends. The main
objective of MIMO technology is to improve bit error rate
(BER) or the data rate of the communication by applying
signal processing techniques at each side of the system. The
capacity increases linearly with the number of antennas
while using MIMO however it gradually saturates. MIMO
can obtain both multiplexing gain and diversity gain and can
help significantly increase the system capacity. The earliest
studies considering MIMO channels were carried out.
Proceedings of International Conference on Advances in Engineering and Technology
www.iaetsd.in
ISBN : 978 - 1505606395
International Association of Engineering and Technology for Skill Development
65
3. MIMO can be divided into two main classes, spatial
multiplexing (SM) and STC. In a wireless communication
system the mobile transceiver has a limited power and also
the device is so small in size that placing multiple antennas
on it would lead to correlation at the antennas due to small
separation between them. To avoid this, the better thing to
do is to use multiple transmit antennas on the base station
and the mobile will have only one. This scenario is known
as Multiple Input Single Output (MISO) transmit-diversity.
A system with two transmit and one receive antenna is a
special case and is known as AlamoutiSTBC. The Alamouti
scheme is well known since it provides full transmit
diversity. For coherent detection it is assumed that perfect
channel state information is available at the receiver.
However, when there is high mobility and the channel
conditions are fluctuating rapidly it may be difficult to
obtain perfect or close to perfect estimates for the channel.
To alleviate this problem another space-time block coding
techniques known as DSTBC has been proposed. In this
technique, two serial transmitted symbols are encoded into
phase differences and the receiver recovers the transmitted
information by comparing the phase of the current symbol
with the previously received symbol.
Transmit Diversity: Transmit diversity (TD) is an important
technique to achieve high data rate communications in
wireless fading environments and has become widely
applied only in the early 2000s. Transmit diversity
techniques can be categorized into open loop and close loop
techniques. For open-loop systems the most popular
transmit-diversity scheme (depicted in Figure 4) is the (2x1)
Alamouti scheme where channel state information and the
code used is known to the receiver.
Fig.3.Open Loop Transmit Diversity
Alamouti Code:Alamouti system is one of the first
spacetimes coding schemes developed for the MIMO
systems which take advantage out of the added diversity of
the space direction. Therefore we do not need extra
bandwidth or much time. We can use this diversity to get a
better bit error rate. At the transmitter side, a block of two
symbols is taken from the source data and sent to the
modulator. Afterwards, the Alamouti space-time encoder
takes the two modulated symbols, in this case x1 and x2 and
creates an encoding matrix x where the symbol x1 and x2
are planned to be transmitted over two transmit antennas in
two consecutive transmit time slots.
The Alamouti encoding matrix is as follows:
= − ∗ ∗ (1)
A block diagram of the Alamouti ST encoder is shown in
Fig.4.
Fig.4. Alamouti Space-Time Encoder
The AlamoutiSTBC scheme which has 2 transmit and Nr
receive antennas candeliver a diversity order of 2 Nr. Also,
since for space time codes the rate is defined as R=k/p
(where k is the number of modulated symbols the encoder
takes as input and p is the number of transmit antennas) for
the AlamoutiSTBC the rate equals 1.
AlamoutiSTBC Decoding with One Receive Antenna:
A block diagram of AlamoutiSTBC decoder is illustrated in
Fig. 5. At the receiver antenna, the signals r1 and r2 received
over two consecutive symbol periods can be written as
follows:
= ( ) = ℎ + ℎ +
= ( + ) = −ℎ ∗
+ ℎ ∗
+ (2)
In order to estimate the transmitted symbols (two in this
case) the decoder needs to obtain the channel state
information (in this work we assume we have perfect CSI)
and also use a signal combiner as could be seen from Fig 5.
Fig.5. Alamouti Space-Time decoder
The channel estimates together with the outputs from the
combiner are then passed on to the Maximum Likelihood
decoder (ML) to obtain the estimates of the transmitted
symbols. Considering that all the constellation points are
equiprobable, the decoder will choose among all pairs of
signals (x1, x2) one that would minimize the distance metric
shown below
d (r , h x + h x ) + d (r , h x∗
+ h x∗)
= |r − h x − h x | + |r + h x∗
− h x∗
| (3)
Proceedings of International Conference on Advances in Engineering and Technology
www.iaetsd.in
ISBN : 978 - 1505606395
International Association of Engineering and Technology for Skill Development
66
4. By Substituting (2) into (3), the maximum likelihood
decoding can be written as
(x , x ) = , ∈ )(|ℎ | + |ℎ | − 1)(|x | + |x | ) +
(x , x ) + (x ,x ) (4)
Where, C is all probable modulated symbol pairs (x1,x2) .x1
and x2 are formed by combining the received signals r1 and
r2 with channel state information known at the receiver. The
combined signals are given by:
= ℎ∗
+ ℎ ∗
= ℎ∗
+ ℎ ∗
(5)
Substituting r1 and r2 from (2), into (5), the combined
signals can be written as,
= (|ℎ | + |ℎ | ) + ℎ∗
+ ℎ ∗
= (|ℎ | + |ℎ | ) + ℎ∗
+ ℎ ∗
(6)
h1 and h2 are a channel realization, the combined signals xi
i =1,2, depends only on , i =1,2. It is possible to split the
maximum likelihood decoding rule into two independent
decoding rules for x1 and x2 as shown below
x = ( ∈ )(|ℎ | + |ℎ | − 1)|x | + ( , )
x = ( ∈ )(|ℎ | + |ℎ | − 1)|x | + ( , )(7)
Since for M-PSK modulated symbols (| h1| +|h2 | -1) |^2
|, i =
1, 2 is constant for all signal points equation (7) can further
be simplified as:
x = ( ∈ ) ( , )
x = ( ∈ ) ( , ) (8)
A. Simple and Robust Synchronization:
Synchronization includes symbol timing, sample clock, and
carrier frequency synchronization. The proposed
synchronizer concentrates on the symbol boundary detection
and the carrier frequency recovery loop as presented in the
following sections.
1) Symbol Boundary Detection: An ISI free region of
symbol timing detection is determined by the difference in
length between the CP and the channel impulse response.
Since the proposed system has two transmit antennas, the
signals transmitted from different antennas may arrive at the
receiver with different delays due to multipath effect.
Therefore, the decided boundary must locate in the common
ISI free region to prevent the respective ISI effects from
other symbols. IEEE 802.16estandard provides three types
of preamble subcarrier sets which can be expressed as [2].
Preamble CarrierSet = s + 3. k
where s= 0, 1, and 2 is the subcarrier set index, and denotes
a running subcarrier index. These subcarriers are modulated.
by BPSK with a specific pseudo-noise (PN) code. Because
the FFT size is not a multiple of 3, the time-domain
preamble symbol is not exactly periodic. Using delay
correlation method is difficult to precisely detect symbol
boundary. Since the preamble symbol is a known sequence
after system acquisition, a match filter corresponding to the
time-domain preamble sequence transmitted from the
antenna can be applied to match the received sample
sequence and obtain the symbol boundary. The match filter
complexity depends on the matching length, so a suitable
length must take both performance and complexity into
consideration. The symbol boundary can be found as
( )
= [ + ]. ( )[ ]
∗
(9)
where and denote the sample indices. When the index
corresponds to the peak of the matching results, the value of
will be found. According to the values of 1 and 2, the final
symbol boundary is decided to be located in the common
ISI free region.
However, the mismatch of oscillator frequency in a receiver
and a transmitter causes frequency offset effects in the
received signals and destroys the characteristic of the
matching results .In order to overcome this problem, we
propose a modified match filter. The filter coefficient
sequence which is the known preamble sequence is
compensated with the possible values of ICFO. An output
peak will appear in matching with the preamble sequence
compensated with the corresponding ICFO. Hence, this
match filter has an additional advantage that the coarse
ICFO can be detected simultaneously. The proposed design
is defined to support the frequency offset to 14 ppm
variation. The maximum CFO is equivalent to 35 kHz in2.5
GHz carrier frequency. Therefore, there are seven possible
ICFO values ranging to.
2) Carry Frequency Recovery: After symbol boundary has
been successfully obtained, the CP position is known. The
CP repeating characteristic can be used to estimate FCFO by
correlating the CP with the corresponding received sample
sequence. However, when the CFO value is in the middle of
two integer values, the accuracy of ICFO detection by using
the match filter method is substantially decreased. Because
the ICFO effects caused by these two integer values are
almost the same, there are two undistinguishable peaks in
the matching results. The undistinguishable peaks caused by
noise and another antenna interference may easily result in
wrong ICFO detection. Therefore, a ping-pong algorithm is
proposed to improve the performance of ICFO detection.
The ping-pong algorithm partitions each CFO region into
the strong region and the weak region depending on the
distance to each integer value, as shown in Fig. 3. The
accurately estimated FCFO value can be used to correct the
ICFO detection .When the estimated FCFO value locates in
the strong region; the matching results have strong
reliability to determine ICFO by detecting the peak value.
When the estimated FCFO value locates in the weak region,
there are two possible peaks in the matching results. Thus,
the ICFO value will be adjusted by the information of the
FCFO value and these two peaks. For example, there are
two peaks appearing in the ICFO values of 0 and 1, and the
Proceedings of International Conference on Advances in Engineering and Technology
www.iaetsd.in
ISBN : 978 - 1505606395
International Association of Engineering and Technology for Skill Development
67
5. FCFO value is correctly estimated to be 0.4located in the
weak region.
If the ICFO value is detected to be1 directly depending on
the output peak, the estimated CFO is1.4 this result is
unreasonable because another peak is 0 but not 2. By using
this ping-pong algorithm, the ICFO value will be correctly
adjusted to be 0.The error probability of ICFO detection is
simulated at the vehicle speed of 60 km/hr with of 16 dB,
where is a ratio of the received bit energy to the noise power
spectral density. The error probability using the direct
detection method rapidly increases to about 0.5 when FCFO
approaches 0.5 (the weak region), whereas it is normally
about. However, the proposed ping-pong scheme is effective
to maintain ICFO error probability at about in the weak
region.
Accurate Two-Stage Channel Estimation
Two major categories of pilot-aided channel estimation
methods are interpolation-based channel estimation methods
and DFT-based channel estimation methods. Interpolation-
based method estimates channel frequency response (CFR)
by interpolating the received pilot subcarriers. This method
is not suitable for outdoor fast fading channels. This is
because the channel coherent bandwidth becomes small, and
using the interpolation-based method with limited pilot
information becomes more difficult to recover channel
variations. DFT-based method focuses on transform domain
to characterize time-domain channel impulse response
(CIR) and effectively improves the performance by
suppressing time-domain noise. Many DFT-based methods
derived from maximum likelihood (ML) scheme have been
studied for OFDM systems with preambles. In order to
further improve the estimation performance, the DF DFT-
based channel estimation method is employed by using
decided data subcarriers as pilot subcarriers to track channel
variations for saving transmission bandwidth and providing
sufficient tracking information.
Fig.6. Proposed Two stage channel Estimator
A two-stage channel estimation method is used to realize a
successful STBC-OFDM system in outdoor mobile
channels. The multipath fading channel is characterized by
CIR consisting of a few significant paths. The delays of
these paths usually vary slowly in time, but the path gains
may vary relatively fast. Therefore, in the initialization
stage, the significant paths are identified during the
preamble symbol time. In the tracking stage, the path gain
variations in the identified path positions will be tracked in
the following data symbol transmission. Fig.4 shows the
architecture of the two-stage channel estimator.
1) Initialization Stage: The operation blocks in this stage are
a preamble match, an IFFT, a straight multipath interference
cancellation (SMPIC)-based de-correlate, and an FFT. The
preamble match correlates the received signal with the
frequency domain preamble symbol to get the preliminary
CFRs of different antenna pairs. Then, the CIR can be
obtained the proposed match filter applied with the ICFO-
compensated coefficients can reduce the CFO effect and
provide the precise symbol boundary detection, and the
ICFO value can be detected simultaneously.
• The proposed ping-pong algorithm using the estimated
FCFO value can refine the ICFO value and improve the
accuracy.
• The proposed two-stage channel estimation can highly
improve the performance in outdoor mobile channels as
compared with the interpolation-based methods that are
frequently adopted in the baseband implementation.• In the
initialization stage, the proposed SMPIC-based de-correlate
uses a straightforward method to identify significant paths
and cancel the multipath interference, which can highly
reduce the implementation cost.• In the tracking stage, the
matrix inverse computation is efficiently avoided by
employing the strongly diagonal property, which can highly
save the computation complexity.
IV. ARCHITECTURE AND CIRCUIT DESIGN
The decision of signal word lengths affects the system
performance and hardware complexity. The output SNR at
the STBC decoder is used as a performance criterion to
determine the appropriate word lengths of each building
block.
Synchronizer
In the match filter, each tap performs complex
multiplication of the coefficient and the received sample. If
the coefficients are quantized into, the tap operation can be
simplified to add or subtract the received sample. It avoids
the multiplier usage and reduces the register requirement.
However, the sign calculation is necessary due to
subtraction, and more hardware effort is required for sign
extension. Therefore, if the signed calculation is avoided,
the hardware and power will be further saved. In the
proposed method, both the real and imaginary parts of the
received sample are quantized into. The quantization loss is
less than 0.8 dB in SNR, and it can be compensated by
increasing the matching length , which costs only a little
hardware overhead When the total numbers of 0’s and
1’sstored in tap registers, denoted as hand, are known, the
number of -1 can also be obtained at the same time.
Therefore, the matching result can be calculated as
Proceedings of International Conference on Advances in Engineering and Technology
www.iaetsd.in
ISBN : 978 - 1505606395
International Association of Engineering and Technology for Skill Development
68
6. Match result = N − (L − N − N ) = 2N − L + N
According to the simulation results at the vehicle speed
of120 km/hr, the matching length of 300 is chosen in this
case so that the symbol miss error probability approaches
the lowest boundary. A monitor circuit is used to count after
each data updating. The tap results are generated by the
logical circuits and are accumulated to obtain by a carry
save adder (CSA) tree. A logical circuit can be simplified to
use only NAND gate and NOR gates. In the proposed
symbol boundary detection, the coefficient sequence is pre-
shifted with the possible values of ICFO, so the ICFO can
be detected simultaneously. The coefficient sequence is
stored in ROM. In order to accumulate the matching results
twice for ICFO detection, an additional circuit is necessary
to store the previous matching results as shown in Fig. 6. If
the control signal is positive, the registers will respectively
store the current matching results of the possible ICFO
values. On the contrary, if a control signal is negative, the
chain of the registers works as the shift-registers for
accumulating the matching results. Finally, the accumulated
results are passed to the comparator to select the two ICFO
values that have maximum peaks in the accumulated results.
Fig.7 Proposed Downlink base band receiver
Fig. 8 Proposed OFDM system with two transmitters and
one receiver
V. SIMULATION RESULTS
MATLAB outputs: In the present work two transmitters and
one receiver has been used to detect the output signal using
MATLAB.
Fig.9. Bit error rate for the signal to noise ratio
Fig. 9is the MATLAB result for the OFDM architecture by
increasing the fading noise between the transmitter and
reciever. The graphs determines the linear decrease in the
error rate by increasing signal to noise ratio.
Fig.10.Bit error rate with respect to the mobility of wlan
Fig. 10 plotted by the MATLAB determines the speed of
the MAN in motion. Even though the speed increases upto
certain rage BER stays in the constant by our proposed
method.
Fig.11. Bit error rate with respect to noise ratio fordifferent
antenna number
Proceedings of International Conference on Advances in Engineering and Technology
www.iaetsd.in
ISBN : 978 - 1505606395
International Association of Engineering and Technology for Skill Development
69
7. Bit error rate for the proposed method when compared
with different transmit anntenas for channel estimation
XILINX outputs:To validate the MATLAB code same input
parameters has been taken to write the code in XILINX
software. The simulation results predicted in XILINX are
Transmitter:
Fig.12 Top module simulation of transmitter
The above simulation shows the input of the transmitter
and the output of the STBCOFDM transmitter the number
of transmit antennas are two.
Conjugate module:
Fig.13.Simulation of STBCencoder
The above simulation is to find the conjugate of the input
and encoded using almouti scheme almouti scheme is the
format of the input is paved in the 2 transmit antenna
IFFT module:
Fig.14.Simulation of IFFT module
To make the serial data to parallel IFFT is implemented for
each transmitter.
Receiver:
Fig.15 Top module simulation of receiver
Signal detection
The above simulation shows the input of the receiver and
output of the STBCOFDM receiver the number of receiver
antenna are one.
Fig.16.Signal detection
The above is to check the guard band interval and
implements the FCFO methodology to correlate the both
carrier wave in Transreceiver.
Find max:
Fig.17. Simulation of find maximum
The above simulation is to find the maximum value with
respective to addition two signals.
Fig.18. Simulation of FFT module
Proceedings of International Conference on Advances in Engineering and Technology
www.iaetsd.in
ISBN : 978 - 1505606395
International Association of Engineering and Technology for Skill Development
70
8. Fig.19. Simulation of STBC decoder
VI. CONCLUSION
In this paper, we propose a downlink baseband receiver
formobile WMAN that is applied in the STBC-OFDM
systemwith two transmit antennas and one receive antenna.
A simplesymbol boundary detector, a carrier frequency
recovery loopmodified by the ping-pong algorithm, and an
accurate two-stagechannel estimator are effectively
implemented. Although thetwo-stage channel estimator
requires higher hardware costas compared with the
interpolation-based channel estimators,it has significant
performance improvement for successfully realizing the
STBC-OFDM system in outdoor mobile environments.From
the simulation results, we have shown that theproposed
receiver improves about 8.5 dB of the normalizedMSE for
16QAM modulation as compared with that adoptingthe 2-D
interpolation methods in multipath fading
channels.Moreover, under the vehicle speed of 120 km/hr,
the convolutionalcoded BER for 16QAM modulation can
achieveless than10-6
with coded rate of 1/2. The proposed
receiverdesigned in 90-nm CMOS technology can support
up to 27.32Mbps (un-coded) downlink throughput under 10
MHz channelbandwidth. This design has a core area of
2.4×12.41 mm anddissipates 68.48 mW at 78.4 MHz
operating frequency. Withverifications through all of the
simulations and design results,the proposed baseband
receiver can provide a solid foundationfor WMAN in fixed
and mobile wireless communication.
VII. REFERENCES
[1] Hsiao-Yun Chen, Member, IEEE, Jyun-Nan Lin,
Hsiang-Sheng Hu, and Shyh-Jye Jou, Senior Member,
IEEE,“STBC-OFDM Downlink Baseband Receiver
ForMobile WMAN”,IEEE Transactions on Very Large
Scale Integration (VLSI) Systems, Vol. 21, No. 1, January
2013.
[2] Local and Metropolitan Area Networks Part 16: Air
Interface forFixed Broadband Wireless Access Systems,
IEEE Std. 802.16-2004,Oct. 2004.
[3] Local andMetropolitan Area Networks Part 16: Air
Interface for Fixedand Mobile Broadband Wireless Access
Systems, IEEE Std. 802.16e-2005, Feb. 2006.
[4] S. M. Alamouti, “A simple transmit diversity technique
for wirelesscommunications,” IEEE J. Select. Areas
Commun, vol. 16, no. 8, pp.1451–1458, Oct. 1998.
[5] M. L. Ku and C. C. Huang, “A complementary codes
pilot-based transmitterdiversity technique for OFDM
systems,” IEEE Trans. Wirel.Commun, vol. 5, no. 3, pp.
504–508, Mar. 2006.
[6] J. N. Lin, H. Y. Chen, and S. J. Jou, “Symbol and carrier
frequencyoffset synchronization for IEEE 802.16e,” in Proc.
IEEE Int. Symp.Circuits Syst., 2008, pp. 3082–3085.
[7] H. Y. Chen,M. L. Ku, S. J. Jou, and C. C. Huang, “A
robust channelestimator for high-mobility STBC-OFDM
systems,” IEEE Trans. CircuitsSyst. I, Reg. Papers, vol. 57,
no. 4, pp. 925–936, Apr. 2010.
[8] L. Deneire, P. Vandenameele, L. van der Perre, B.
Gyselinckx, and M.Engels, “A low-complexity ML channel
estimator for OFDM,” IEEETrans. Commun., vol. 51, no. 2,
pp. 135–140, Feb. 2003.
[9] M. Morelli and U. Mengali, “A comparison of pilot-
aided channel estimationmethods for OFDM systems,”
IEEE Trans. Signal Process,vol. 49, no. 12, pp. 3065–3073,
Dec. 2001.
[10] J. H. Park, M. K. Oh, and D. J. Park, “New channel
estimation exploitingreliable decision-feedback symbols for
OFDM systems,” inProc. Int. Conf. Commun., 2006, pp.
3046–3051.
[11] M. L. Ku and C. C. Huang, “A derivation on the
equivalence betweenNewton’s method and DF DFT-based
method for channel estimationin OFDM systems,” IEEE
Trans. Wirel. Commun, vol. 7, no. 10, pp.3982–3987, Oct.
2008.
[12] T. S. Rappaport,Wireless Communications: Principles
and Practice.Englewood Cliffs, NJ: Prentice-Hall, 2002.
Proceedings of International Conference on Advances in Engineering and Technology
www.iaetsd.in
ISBN : 978 - 1505606395
International Association of Engineering and Technology for Skill Development
71