The document discusses smart antennas and MAC protocols in mobile ad hoc networks. It covers topics such as:
1) System models and algorithms for optimum beamformer design and adaptive beamforming.
2) Direction-of-arrival estimation methods including MF, MVDR, and MUSIC.
3) Schemes using directional antennas in the MAC layer including Vaidya's scheme 1 which uses directional RTS and omnidirectional CTS.
Radio Signal Classification with Deep Neural NetworksKachi Odoemene
This document discusses the author's approach to classifying radio signal modulations using deep neural networks in the 2018 Army Signal Classification Challenge. It summarizes the author's 6th place solution using two deep learning models: a ResNet architecture and a CLDNN architecture. Key details provided include the dataset and evaluation metrics, model architectures and implementations, training procedures, performance on validation and test sets, and challenges faced in the competition.
Automatic digital modulation recognition using articialHemant Ingale
This document discusses a study on automatic digital modulation recognition using artificial neural networks and genetic algorithms. It presents a neural network-based approach for recognizing ten different digital modulation types from signal features. Resilient backpropagation and genetic algorithm-based feature selection are employed to improve recognition performance. Results show the neural network with selected features achieves over 99% accuracy on most signal-to-noise ratios using only six features.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
CS Based Channel Estimation for OFDM Systems under Long Delay Channels Using ...IJERA Editor
Orthogonal frequency division multiplexing (OFDM) is a technique which are used in the next-generation wireless communication. Channel estimation in the OFDM technique is one of the big challenges, ever since high-resolution channel estimation can significantly improve the equalization at the receiver and consequently enhance the communication performances. Channel computation using superimposed pilot sequences is also a fully new area, idea for using superimposed pilot sequences has been proposed by various authors for different applications. In this paper, we are introduced a high accurate, low complexity compressive sensing (CS) based channel estimation namely Auxiliary information based Subspace Pursuit (ASP) in TFT-OFDM systems. ASP based channel estimation in TFT-OFDM system is based on two steps. First is, by exploiting the signal structure of recently proposed TDM-OFDM scheme, the supporting channel information is obtained. Second is, we propose the supporting information based subspace pursuit (SP) algorithm to use a very small amount of frequency domain pilots embedded in the OFDM block used for the exact channel estimation. Moreover, the obtained auxiliary channel information is adopted to reduce the complexity of the conventional SP algorithm. Simulation results demonstrate a important reduction of the number of pilots relative to least-squares channel estimation and supporting high-order modulations like 256 QAM.
OFDM is a high-speed wireless transmission technology that divides the available spectrum into multiple orthogonal subcarriers. It is implemented as OFDMA to support multi-user communication. OFDM provides advantages over single carrier transmission by combating inter-symbol interference and frequency selective fading. It works by encoding data over multiple carrier frequencies, with spacing between carriers chosen so that the carriers are orthogonal to each other. This allows high data rates without overlapping signals at a receiver.
A Wireless Sensor Network (WSN) is an autonomous and self-organizing network without any pre-established
infrastructure which offers many advantages in military applications and emergency areas. Source Localization is one of the important monitoring tasks of the WSN. It provides the accurate position of the source using various positioning technologies. In this paper an Impulse Radio Ultra wideband (IR-UWB) positioning system with a two-antenna receiver is used to estimate the Time of arrival (TOA) and Direction of arrival (DOA) positioning parameters. A two dimensional (2D) multiple signal classification (MUSIC) algorithm is used to estimate these parameters but it has much higher computational
complexity and also requires 2D spectral peak search. A Successive Multiple signal classification (MUSIC) algorithm is proposed in this paper which estimates the parameters jointly and gets paired automatically. It avoids the two dimensional peak searches and reduces the complexity compared to the existing methods 2D-MUSIC, Root-MUSIC, Matrix Pencil algorithm, Propagator method and Estimation of Signal Parameters via Rotational Invariance Techniques (ESPRIT) algorithm.
Keywords--Time of arrival (TOA), Direction of arrival (DOA), Impulse Radio Ultra Wideband (IR-UWB), Multiple
Signal Classification (MUSIC).
This document discusses frame and burst acquisition in a TDMA satellite communication network where transmissions may occur on different transponders. It presents the following key points:
1) A unique word pattern is used to aid in the acquisition process and detect the frame. Soft-decision detection of QPSK modulated signals is used in an additive white Gaussian channel.
2) The probability of detection is low when the false alarm rate is low, leading to a long acquisition time. Conversely, a high false alarm rate yields a high probability of detection and shorter acquisition time.
3) An analysis is presented of the unique word detection process at a traffic terminal, assuming carrier and bit timing have been partially recovered from a reference burst
Low Complexity Multi-User MIMO Detection for Uplink SCMA System Using Expecta...TELKOMNIKA JOURNAL
Sparse code multiple access (SCMA), which combines the advantages of low density signature
(LDS) and code-division multiple access (CDMA), is regarded as one of the promising modulation technique
candidate for the next generation of wireless systems. Conventionally, the message passing algorithm (MPA)
is used for data detector at the receiver side. However, the MPA-SCMA cannot be implemented in the next
generation wireless systems, because of its unacceptable complexity cost. Specifically, the complexity of
MPA-SCMA grows exponentially with the number of antennas. Considering the use of high dimensional
systems in the next generation of wireless systems, such as massive multi-user MIMO systems, the conventional
MPA-SCMA is prohibitive. In this paper, we propose a low complexity detector algorithm named the
expectation propagation algorithm (EPA) for SCMA. Mainly, the EPA-SCMA solves the complexity problem
of MPA-SCMA and enables the implementation of SCMA in massive MU-MIMO systems. For instance, the
EPA-SCMA also enables the implemantation of SCMA in the next generation wireless systems. We further
show that the EPA can achieve the optimal detection performance as the numbers of transmit and receive
antennas grow. We also demonstrate that a rotation design in SCMA codebook is unnecessary, which is
quite rather different from the general assumption.
Radio Signal Classification with Deep Neural NetworksKachi Odoemene
This document discusses the author's approach to classifying radio signal modulations using deep neural networks in the 2018 Army Signal Classification Challenge. It summarizes the author's 6th place solution using two deep learning models: a ResNet architecture and a CLDNN architecture. Key details provided include the dataset and evaluation metrics, model architectures and implementations, training procedures, performance on validation and test sets, and challenges faced in the competition.
Automatic digital modulation recognition using articialHemant Ingale
This document discusses a study on automatic digital modulation recognition using artificial neural networks and genetic algorithms. It presents a neural network-based approach for recognizing ten different digital modulation types from signal features. Resilient backpropagation and genetic algorithm-based feature selection are employed to improve recognition performance. Results show the neural network with selected features achieves over 99% accuracy on most signal-to-noise ratios using only six features.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
CS Based Channel Estimation for OFDM Systems under Long Delay Channels Using ...IJERA Editor
Orthogonal frequency division multiplexing (OFDM) is a technique which are used in the next-generation wireless communication. Channel estimation in the OFDM technique is one of the big challenges, ever since high-resolution channel estimation can significantly improve the equalization at the receiver and consequently enhance the communication performances. Channel computation using superimposed pilot sequences is also a fully new area, idea for using superimposed pilot sequences has been proposed by various authors for different applications. In this paper, we are introduced a high accurate, low complexity compressive sensing (CS) based channel estimation namely Auxiliary information based Subspace Pursuit (ASP) in TFT-OFDM systems. ASP based channel estimation in TFT-OFDM system is based on two steps. First is, by exploiting the signal structure of recently proposed TDM-OFDM scheme, the supporting channel information is obtained. Second is, we propose the supporting information based subspace pursuit (SP) algorithm to use a very small amount of frequency domain pilots embedded in the OFDM block used for the exact channel estimation. Moreover, the obtained auxiliary channel information is adopted to reduce the complexity of the conventional SP algorithm. Simulation results demonstrate a important reduction of the number of pilots relative to least-squares channel estimation and supporting high-order modulations like 256 QAM.
OFDM is a high-speed wireless transmission technology that divides the available spectrum into multiple orthogonal subcarriers. It is implemented as OFDMA to support multi-user communication. OFDM provides advantages over single carrier transmission by combating inter-symbol interference and frequency selective fading. It works by encoding data over multiple carrier frequencies, with spacing between carriers chosen so that the carriers are orthogonal to each other. This allows high data rates without overlapping signals at a receiver.
A Wireless Sensor Network (WSN) is an autonomous and self-organizing network without any pre-established
infrastructure which offers many advantages in military applications and emergency areas. Source Localization is one of the important monitoring tasks of the WSN. It provides the accurate position of the source using various positioning technologies. In this paper an Impulse Radio Ultra wideband (IR-UWB) positioning system with a two-antenna receiver is used to estimate the Time of arrival (TOA) and Direction of arrival (DOA) positioning parameters. A two dimensional (2D) multiple signal classification (MUSIC) algorithm is used to estimate these parameters but it has much higher computational
complexity and also requires 2D spectral peak search. A Successive Multiple signal classification (MUSIC) algorithm is proposed in this paper which estimates the parameters jointly and gets paired automatically. It avoids the two dimensional peak searches and reduces the complexity compared to the existing methods 2D-MUSIC, Root-MUSIC, Matrix Pencil algorithm, Propagator method and Estimation of Signal Parameters via Rotational Invariance Techniques (ESPRIT) algorithm.
Keywords--Time of arrival (TOA), Direction of arrival (DOA), Impulse Radio Ultra Wideband (IR-UWB), Multiple
Signal Classification (MUSIC).
This document discusses frame and burst acquisition in a TDMA satellite communication network where transmissions may occur on different transponders. It presents the following key points:
1) A unique word pattern is used to aid in the acquisition process and detect the frame. Soft-decision detection of QPSK modulated signals is used in an additive white Gaussian channel.
2) The probability of detection is low when the false alarm rate is low, leading to a long acquisition time. Conversely, a high false alarm rate yields a high probability of detection and shorter acquisition time.
3) An analysis is presented of the unique word detection process at a traffic terminal, assuming carrier and bit timing have been partially recovered from a reference burst
Low Complexity Multi-User MIMO Detection for Uplink SCMA System Using Expecta...TELKOMNIKA JOURNAL
Sparse code multiple access (SCMA), which combines the advantages of low density signature
(LDS) and code-division multiple access (CDMA), is regarded as one of the promising modulation technique
candidate for the next generation of wireless systems. Conventionally, the message passing algorithm (MPA)
is used for data detector at the receiver side. However, the MPA-SCMA cannot be implemented in the next
generation wireless systems, because of its unacceptable complexity cost. Specifically, the complexity of
MPA-SCMA grows exponentially with the number of antennas. Considering the use of high dimensional
systems in the next generation of wireless systems, such as massive multi-user MIMO systems, the conventional
MPA-SCMA is prohibitive. In this paper, we propose a low complexity detector algorithm named the
expectation propagation algorithm (EPA) for SCMA. Mainly, the EPA-SCMA solves the complexity problem
of MPA-SCMA and enables the implementation of SCMA in massive MU-MIMO systems. For instance, the
EPA-SCMA also enables the implemantation of SCMA in the next generation wireless systems. We further
show that the EPA can achieve the optimal detection performance as the numbers of transmit and receive
antennas grow. We also demonstrate that a rotation design in SCMA codebook is unnecessary, which is
quite rather different from the general assumption.
This document discusses an algorithm for estimating the velocity of multiple reflecting objects using standard OFDM communication signals without any specific coding of the transmitted data. The algorithm processes the symbols that compose the OFDM symbols directly rather than the baseband signals. Range and Doppler information can be extracted from the received OFDM signal and used to implement radar sensing functions in a joint radar and communication system, such as for vehicular applications. Simulation and measurement results demonstrating the algorithm's effectiveness are presented.
n this paper channel state information is exploited for improving system performance. The per
formance parameters of
the
Multiple Input Multiple Output system is better and are even achieved using additional RF modules that are required as multi
ple
antennas are employed. To reduce the cost associated with the multiple RF modules, antenna selection
techniques can be used to
employ a smaller number of RF modules than the number of transmit antennas. The exploiting of information for complexity red
uced
antenna selection is performed for achieving high channel capacity. Simulation r
esults show
that th
e channel capacity increases in
proportion to the number of the selected antennas
V-BLAST is a technique that uses multiple antennas at the transmitter and receiver to increase data rates over wireless channels. It stands for Vertical Bell Laboratories Layered Space Time. V-BLAST is a simplified version of D-BLAST that reduces computational complexity by transmitting each data stream through a single antenna (horizontally layered). At the receiver, signals are detected by first nulling out interference from other streams through linear weighting, then detecting and canceling streams starting from the highest SNR stream. V-BLAST is used in wireless communication standards like 802.11n, 4G, LTE, and WiMAX to implement MIMO technology.
Multiuser MIMO Vector Perturbation Precodingadeelrazi
This paper proposes methods for sum rate optimization in multi-user MIMO systems using vector perturbation precoding. It derives an expression for sum rate in terms of the average transmitted vector energy. It then uses this to obtain a high-SNR upper bound on sum rate and proposes an extension of vector perturbation that allocates different rates to different users. It also proposes a low-complexity user scheduling algorithm as a method for rate allocation.
Performance of enhanced lte otdoa position ing approach through nakagami-m fa...Elmourabit Ilham
This document analyzes the performance of an enhanced LTE OTDOA positioning technique called Adaptive OTDOA (A-OTDOA) through a Nakagami-m fading channel. A-OTDOA uses adaptive filters to cancel noise from received positioning reference signals before estimating time differences of arrival, improving accuracy. The document introduces A-OTDOA and the Normalized Least Mean Square adaptive algorithm used. It then discusses modeling the propagation environment, including Nakagami-m fading channels, to test A-OTDOA's performance in a worst-case scenario without line of sight.
An analtical analysis of w cdma smart antennamarwaeng
The document analyzes the signal-to-interference-noise ratio (SINR) performance of two beamforming methods, complex conjugate (CC) and direction-of-arrival (DOA), used in Wideband Code Division Multiple Access (W-CDMA) smart antenna systems. It derives analytic SINR evaluation equations for both methods under different channel conditions. The results show that the CC and DOA methods provide the same mean SINR performance but the CC method is more robust to channel estimation errors. Simulation results are presented to verify the analytic performance and robustness analyses.
This document summarizes research on reducing peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. It discusses using a companding technique with Gaussian distribution to compress the signal before transmission and decompress it upon reception. The key aspects covered are: applying a compander and decompander with Gaussian distribution parameters at the transmitter and receiver; how the central limit theorem allows the sum of subcarriers to approximate a Gaussian distribution for large numbers; and how this technique reduces PAPR by increasing average power while keeping peak power the same. Performance is analyzed by simulating PAPR and bit error rate with and without companding under different parameters.
This three day course is intended for practicing systems engineers who want to learn how to apply model-driven systems Successful systems engineering requires a broad understanding of the important principles of modern spacecraft communications. This three-day course covers both theory and practice, with emphasis on the important system engineering principles, tradeoffs, and rules of thumb. The latest technologies are covered. <p>
Design Ofdm System And Remove Nonlinear Distortion In OFDM Signal At Transmit...Rupesh Sharma
although OFDM seems to be a solution to keep up with
the demand of increasing data rates, it has some drawbacks.
Sensitivity to high PAPR is the most significant of these
drawbacks. The main objective of this paper was to investigate
and document the effects of PAPR on the performance of OFDM
based digital communications under different channel conditions.
A step-by-step approach was adopted in order to achieve the
objective of this paper. The first step is to provide a basic
background on the principles of OFDM. The reasons for the
PAPR and a theoretical analysis of these effects on OFDM
systems are documented. The OFDM system has a high peak-toaverage
power ratio (PAPR) that can cause unwanted saturation
in the power amplifiers, leading to in-band distortion and out-ofband
radiation. To be able to observe the system behavior, the
simulation results for different channel models are presented in
graphical form. Next, the simulation results obtained in this work
are compared to the simulation results reported in related studies
This document provides information about Quadrature Amplitude Modulation (QAM). It begins with an objective to analyze the bit error rate performance of M-QAM modulation over fading channels. It then introduces QAM, explaining that it modulates data onto carriers using both amplitude and phase variations. The document outlines the basic working principles of QAM modulation and demodulation. It discusses constellation diagrams and provides examples of 16-QAM, 64-QAM, and 256-QAM constellations. The document notes some advantages of QAM, such as high data rates, and some disadvantages, such as increased susceptibility to noise in higher order QAM. It concludes that QAM is widely used in radio communications due to its ability to increase data
This document discusses carrier synchronization techniques in digital communication systems. It begins with an introduction to the need for carrier recovery and symbol synchronization at the receiver. It then covers maximum likelihood estimation of signal parameters including carrier phase. Next, it describes carrier phase estimation using a phase-locked loop and decision-directed loops. It explains how the phase-locked loop works to continuously track and update the carrier phase estimate. Finally, it provides an example of decision-directed carrier phase estimation for a double-sideband suppressed carrier pulse amplitude modulation signal.
This document provides a feasibility study for evolving UTRA and UTRAN, including:
- An introduction to MIMO and its different gains for multiple antenna systems.
- Frame structures, peak rates, and other physical layer parameters for LTE downlink and uplink using OFDMA. Frame structures include FDD and TDD types.
- A comparison of LTE and WiMAX frame structures and spectrum flexibility.
- Details on OFDM concepts like subcarrier allocation, guard intervals, and peak-to-average power ratio in OFDM signals.
EE402B Radio Systems and Personal Communication Networks notesHaris Hassan
Programmes in which available:
Masters of Engineering - Electrical and Electronic
Engineering. Masters of Engineering - Electronic
Engineering and Computer Science. Master of Science -
Communication Systems and Wireless Networking.
Master of Science - Smart Telecom and Sensing
Networks. Master of Science - Photonic Integrated
Circuits, Sensors and Networks.
This document discusses multiple-input multiple-output (MIMO) systems. It begins by outlining the motivations and aspirations for developing MIMO, including achieving high data rates near 1 Gbps while maintaining quality of service. It then covers MIMO system modeling and capacity studies. Different MIMO designs are presented that aim to achieve spatial multiplexing gain or diversity gain. Practical MIMO systems and architectures like V-BLAST are described. Networking applications of MIMO including MAC protocols are also discussed.
OFDM is a digital multi-carrier modulation technique that divides the available spectrum into multiple orthogonal subcarriers. It allows high spectral efficiency by spacing the carriers to maintain orthogonality even when their spectra overlap. The document provides an intuitive explanation of OFDM using analogies like a shower head vs faucet and multiple smaller trucks vs one large truck. It explains how OFDM provides resistance to interference by spreading data across orthogonal subcarriers rather than a single carrier. The key concept of orthogonality allows the subcarriers to overlap without interference by ensuring the area under one subcarrier's frequency multiplied by another is always zero.
The document discusses channel modeling and Kalman filter-based estimation for OFDM wireless communication systems. It provides an introduction to OFDM systems and outlines the channel modeling process, including modeling the channel as a multipath frequency selective fading channel using a tapped delay line. It also discusses implementing channel estimation using a Kalman filter and presenting results on simulating OFDM signal transmission through a Rayleigh fading channel. The goal is to accurately estimate the channel fading parameters using a joint time-frequency domain estimation model.
1. The document proposes a scheme called Superimposed Spatial Modulation (SSM) that allows for doubling of information conveyed in the spatial position of transmitting antennas.
2. SSM superimposes two independent spatial modulation systems on the same antenna array. Each system transmits different components of orthogonal symbols.
3. This approach increases spectral efficiency over conventional spatial modulation by doubling the size of the possible antenna constellations.
Candidate Core Selection for Load-Balanced Multicore Shared Tree MulticastingKoushik Sinha
Multicasting can be done in two different ways: source based tree approach and shared tree approach. Protocols such as Core Based Tree (CBT), Protocol Independent Multicasting Sparse Mode (PIM-SM) use shared tree approach. Shared tree approach is preferred over source-based tree approach because in the later construction of minimum cost tree per source is needed unlike a single shared tree in the former approach. We present a candidate core selection approach for shared tree multicasting so that in a multicast session different senders can select different cores from the candidate core set based on the senders’ physical locations to allow an efficient multicore multicasting approach.
Paper reference link: https://www.researchgate.net/publication/303993360_Locality_based_Core_Selection_for_Multicore_Shared_Tree_Multicasting?ev=prf_pub
This document provides an outline and introduction to direct sequence spread spectrum (DSSS) and code division multiple access (CDMA). It discusses key concepts such as anti-jam margin, generation of spreading codes, properties of pseudo-noise codes, acquisition and tracking in CDMA systems, CDMA capacity, and throughput efficiency. Advantages of CDMA for satellite networks include interference rejection and asynchronized access, while the main disadvantage is low throughput efficiency.
The document discusses the syllabus for the EC6801 Wireless Communication course. It covers 5 units: wireless channels, cellular architecture, digital signaling for fading channels, multipath mitigation techniques, and multiple antenna techniques. The key topics covered include path loss models, small scale fading parameters, multiple access techniques, diversity combining, equalization, MIMO systems and capacity in fading channels. The document also provides sample problems for the first two units.
Positioning techniques in 3 g networks (1)kike2005
Independent Study Presentation on Positioning Techniques in 3G Networks. The presentation discusses [1] positioning parameters in 3G networks such as RSCP, RSS, RTT, and AoA; and [2] positioning techniques including enhancements to the basic Cell ID method, OTDOA methods using IPDL and CVB, the Database Correlation Method using power delay profiles, and the Pilot Correlation Method using pilot signal measurements. Simulation results are presented showing the accuracy of some of these techniques.
This senior design project involves designing an FM-CW automobile radar system and algorithms for pedestrian recognition in foggy conditions. The system will use a 77 GHz radar with a phased array antenna to scan a range of 100 meters. Key aspects of the design include antenna design using a patch microstrip array, an LFM-CW waveform, signal processing algorithms for target detection and classification, and constant false alarm rate detection accounting for noise levels and range. The goal is to improve pedestrian detection performance in fog through improved range resolution and Doppler analysis.
This document discusses an algorithm for estimating the velocity of multiple reflecting objects using standard OFDM communication signals without any specific coding of the transmitted data. The algorithm processes the symbols that compose the OFDM symbols directly rather than the baseband signals. Range and Doppler information can be extracted from the received OFDM signal and used to implement radar sensing functions in a joint radar and communication system, such as for vehicular applications. Simulation and measurement results demonstrating the algorithm's effectiveness are presented.
n this paper channel state information is exploited for improving system performance. The per
formance parameters of
the
Multiple Input Multiple Output system is better and are even achieved using additional RF modules that are required as multi
ple
antennas are employed. To reduce the cost associated with the multiple RF modules, antenna selection
techniques can be used to
employ a smaller number of RF modules than the number of transmit antennas. The exploiting of information for complexity red
uced
antenna selection is performed for achieving high channel capacity. Simulation r
esults show
that th
e channel capacity increases in
proportion to the number of the selected antennas
V-BLAST is a technique that uses multiple antennas at the transmitter and receiver to increase data rates over wireless channels. It stands for Vertical Bell Laboratories Layered Space Time. V-BLAST is a simplified version of D-BLAST that reduces computational complexity by transmitting each data stream through a single antenna (horizontally layered). At the receiver, signals are detected by first nulling out interference from other streams through linear weighting, then detecting and canceling streams starting from the highest SNR stream. V-BLAST is used in wireless communication standards like 802.11n, 4G, LTE, and WiMAX to implement MIMO technology.
Multiuser MIMO Vector Perturbation Precodingadeelrazi
This paper proposes methods for sum rate optimization in multi-user MIMO systems using vector perturbation precoding. It derives an expression for sum rate in terms of the average transmitted vector energy. It then uses this to obtain a high-SNR upper bound on sum rate and proposes an extension of vector perturbation that allocates different rates to different users. It also proposes a low-complexity user scheduling algorithm as a method for rate allocation.
Performance of enhanced lte otdoa position ing approach through nakagami-m fa...Elmourabit Ilham
This document analyzes the performance of an enhanced LTE OTDOA positioning technique called Adaptive OTDOA (A-OTDOA) through a Nakagami-m fading channel. A-OTDOA uses adaptive filters to cancel noise from received positioning reference signals before estimating time differences of arrival, improving accuracy. The document introduces A-OTDOA and the Normalized Least Mean Square adaptive algorithm used. It then discusses modeling the propagation environment, including Nakagami-m fading channels, to test A-OTDOA's performance in a worst-case scenario without line of sight.
An analtical analysis of w cdma smart antennamarwaeng
The document analyzes the signal-to-interference-noise ratio (SINR) performance of two beamforming methods, complex conjugate (CC) and direction-of-arrival (DOA), used in Wideband Code Division Multiple Access (W-CDMA) smart antenna systems. It derives analytic SINR evaluation equations for both methods under different channel conditions. The results show that the CC and DOA methods provide the same mean SINR performance but the CC method is more robust to channel estimation errors. Simulation results are presented to verify the analytic performance and robustness analyses.
This document summarizes research on reducing peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. It discusses using a companding technique with Gaussian distribution to compress the signal before transmission and decompress it upon reception. The key aspects covered are: applying a compander and decompander with Gaussian distribution parameters at the transmitter and receiver; how the central limit theorem allows the sum of subcarriers to approximate a Gaussian distribution for large numbers; and how this technique reduces PAPR by increasing average power while keeping peak power the same. Performance is analyzed by simulating PAPR and bit error rate with and without companding under different parameters.
This three day course is intended for practicing systems engineers who want to learn how to apply model-driven systems Successful systems engineering requires a broad understanding of the important principles of modern spacecraft communications. This three-day course covers both theory and practice, with emphasis on the important system engineering principles, tradeoffs, and rules of thumb. The latest technologies are covered. <p>
Design Ofdm System And Remove Nonlinear Distortion In OFDM Signal At Transmit...Rupesh Sharma
although OFDM seems to be a solution to keep up with
the demand of increasing data rates, it has some drawbacks.
Sensitivity to high PAPR is the most significant of these
drawbacks. The main objective of this paper was to investigate
and document the effects of PAPR on the performance of OFDM
based digital communications under different channel conditions.
A step-by-step approach was adopted in order to achieve the
objective of this paper. The first step is to provide a basic
background on the principles of OFDM. The reasons for the
PAPR and a theoretical analysis of these effects on OFDM
systems are documented. The OFDM system has a high peak-toaverage
power ratio (PAPR) that can cause unwanted saturation
in the power amplifiers, leading to in-band distortion and out-ofband
radiation. To be able to observe the system behavior, the
simulation results for different channel models are presented in
graphical form. Next, the simulation results obtained in this work
are compared to the simulation results reported in related studies
This document provides information about Quadrature Amplitude Modulation (QAM). It begins with an objective to analyze the bit error rate performance of M-QAM modulation over fading channels. It then introduces QAM, explaining that it modulates data onto carriers using both amplitude and phase variations. The document outlines the basic working principles of QAM modulation and demodulation. It discusses constellation diagrams and provides examples of 16-QAM, 64-QAM, and 256-QAM constellations. The document notes some advantages of QAM, such as high data rates, and some disadvantages, such as increased susceptibility to noise in higher order QAM. It concludes that QAM is widely used in radio communications due to its ability to increase data
This document discusses carrier synchronization techniques in digital communication systems. It begins with an introduction to the need for carrier recovery and symbol synchronization at the receiver. It then covers maximum likelihood estimation of signal parameters including carrier phase. Next, it describes carrier phase estimation using a phase-locked loop and decision-directed loops. It explains how the phase-locked loop works to continuously track and update the carrier phase estimate. Finally, it provides an example of decision-directed carrier phase estimation for a double-sideband suppressed carrier pulse amplitude modulation signal.
This document provides a feasibility study for evolving UTRA and UTRAN, including:
- An introduction to MIMO and its different gains for multiple antenna systems.
- Frame structures, peak rates, and other physical layer parameters for LTE downlink and uplink using OFDMA. Frame structures include FDD and TDD types.
- A comparison of LTE and WiMAX frame structures and spectrum flexibility.
- Details on OFDM concepts like subcarrier allocation, guard intervals, and peak-to-average power ratio in OFDM signals.
EE402B Radio Systems and Personal Communication Networks notesHaris Hassan
Programmes in which available:
Masters of Engineering - Electrical and Electronic
Engineering. Masters of Engineering - Electronic
Engineering and Computer Science. Master of Science -
Communication Systems and Wireless Networking.
Master of Science - Smart Telecom and Sensing
Networks. Master of Science - Photonic Integrated
Circuits, Sensors and Networks.
This document discusses multiple-input multiple-output (MIMO) systems. It begins by outlining the motivations and aspirations for developing MIMO, including achieving high data rates near 1 Gbps while maintaining quality of service. It then covers MIMO system modeling and capacity studies. Different MIMO designs are presented that aim to achieve spatial multiplexing gain or diversity gain. Practical MIMO systems and architectures like V-BLAST are described. Networking applications of MIMO including MAC protocols are also discussed.
OFDM is a digital multi-carrier modulation technique that divides the available spectrum into multiple orthogonal subcarriers. It allows high spectral efficiency by spacing the carriers to maintain orthogonality even when their spectra overlap. The document provides an intuitive explanation of OFDM using analogies like a shower head vs faucet and multiple smaller trucks vs one large truck. It explains how OFDM provides resistance to interference by spreading data across orthogonal subcarriers rather than a single carrier. The key concept of orthogonality allows the subcarriers to overlap without interference by ensuring the area under one subcarrier's frequency multiplied by another is always zero.
The document discusses channel modeling and Kalman filter-based estimation for OFDM wireless communication systems. It provides an introduction to OFDM systems and outlines the channel modeling process, including modeling the channel as a multipath frequency selective fading channel using a tapped delay line. It also discusses implementing channel estimation using a Kalman filter and presenting results on simulating OFDM signal transmission through a Rayleigh fading channel. The goal is to accurately estimate the channel fading parameters using a joint time-frequency domain estimation model.
1. The document proposes a scheme called Superimposed Spatial Modulation (SSM) that allows for doubling of information conveyed in the spatial position of transmitting antennas.
2. SSM superimposes two independent spatial modulation systems on the same antenna array. Each system transmits different components of orthogonal symbols.
3. This approach increases spectral efficiency over conventional spatial modulation by doubling the size of the possible antenna constellations.
Candidate Core Selection for Load-Balanced Multicore Shared Tree MulticastingKoushik Sinha
Multicasting can be done in two different ways: source based tree approach and shared tree approach. Protocols such as Core Based Tree (CBT), Protocol Independent Multicasting Sparse Mode (PIM-SM) use shared tree approach. Shared tree approach is preferred over source-based tree approach because in the later construction of minimum cost tree per source is needed unlike a single shared tree in the former approach. We present a candidate core selection approach for shared tree multicasting so that in a multicast session different senders can select different cores from the candidate core set based on the senders’ physical locations to allow an efficient multicore multicasting approach.
Paper reference link: https://www.researchgate.net/publication/303993360_Locality_based_Core_Selection_for_Multicore_Shared_Tree_Multicasting?ev=prf_pub
This document provides an outline and introduction to direct sequence spread spectrum (DSSS) and code division multiple access (CDMA). It discusses key concepts such as anti-jam margin, generation of spreading codes, properties of pseudo-noise codes, acquisition and tracking in CDMA systems, CDMA capacity, and throughput efficiency. Advantages of CDMA for satellite networks include interference rejection and asynchronized access, while the main disadvantage is low throughput efficiency.
The document discusses the syllabus for the EC6801 Wireless Communication course. It covers 5 units: wireless channels, cellular architecture, digital signaling for fading channels, multipath mitigation techniques, and multiple antenna techniques. The key topics covered include path loss models, small scale fading parameters, multiple access techniques, diversity combining, equalization, MIMO systems and capacity in fading channels. The document also provides sample problems for the first two units.
Positioning techniques in 3 g networks (1)kike2005
Independent Study Presentation on Positioning Techniques in 3G Networks. The presentation discusses [1] positioning parameters in 3G networks such as RSCP, RSS, RTT, and AoA; and [2] positioning techniques including enhancements to the basic Cell ID method, OTDOA methods using IPDL and CVB, the Database Correlation Method using power delay profiles, and the Pilot Correlation Method using pilot signal measurements. Simulation results are presented showing the accuracy of some of these techniques.
This senior design project involves designing an FM-CW automobile radar system and algorithms for pedestrian recognition in foggy conditions. The system will use a 77 GHz radar with a phased array antenna to scan a range of 100 meters. Key aspects of the design include antenna design using a patch microstrip array, an LFM-CW waveform, signal processing algorithms for target detection and classification, and constant false alarm rate detection accounting for noise levels and range. The goal is to improve pedestrian detection performance in fog through improved range resolution and Doppler analysis.
This document provides an overview of MIMO (Multiple Input Multiple Output) radar. MIMO radar uses multiple transmit and receive antennas. This allows it to achieve higher angular resolution than traditional phased array radars with fewer antennas. MIMO radar works by having receive antennas separately process signals from different transmit antennas, using techniques like time division multiplexing and binary phase modulation. The virtual array concept enables MIMO radar to greatly increase its degrees of freedom beyond the physical number of antennas. Potential applications of MIMO radar include air surveillance, clutter mitigation, and moving target detection.
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.
Spread spectrum modulation is a wideband modulation technique that provides three main advantages over fixed frequency transmission: resistance to noise/interference, difficulty intercepting signals, and allowing multiple transmissions to efficiently share frequencies. There are two types of spread spectrum systems: averaging systems like direct sequence modulation that spread signals; and avoidance systems like frequency hopping that rapidly change frequencies. Pseudo-noise codes with certain properties are used to spread and despread direct sequence signals. Hybrid spread spectrum systems combine techniques to gain advantages while reducing disadvantages.
This document summarizes two channel estimation methods for MIMO-OFDM systems: blind channel estimation and QRD-M/Kalman filter based detection. Blind channel estimation works by identifying the channel based on knowledge of the channel and data symbols using noise subspace approach and linear precoding. It has fast convergence, requires few OFDM symbols, and can be used with any number of transmit/receive antennas. QRD-M/Kalman filter based detection uses an adaptive complexity QRD-M algorithm and Kalman filters to track individual channels with lower complexity and good tracking ability. It decomposes the received signal into an upper triangular matrix and uses maximum likelihood detection on individual subcarriers. Both methods are analyzed and their advantages/dis
Comparitive analysis of bit error rates of multiple input multiple output tra...slinpublishers
The document compares the bit error rates of multiple input multiple output (MIMO) transmission schemes, including spatial multiplexing, space-time block codes (STBC), and space-time block coded spatial modulation (STBC-SM). It finds that STBC-SM provides better performance than STBC and vertical-Bell labs layered space-time (V-BLAST) spatial multiplexing. Specifically, simulations show STBC-SM has a lower bit error rate than the other schemes when using four transmit and four receive antennas. The document explains the techniques of V-BLAST, STBC, and STBC-SM in detail.
3D METALLIC PLATE LENS ANTENNA BASED BEAMSPACE CHANNEL ESTIMATION TECHNIQUE F...ijwmn
Beamspace channel estimation mechanism for massive MIMO (multiple input multiple output) antenna
system presents a major process to compensate the 5G spectrum challenges caused by the proliferation of
information from mobile devices. However, this estimation is required to ensure the perfect channel state
information (CSI) for lower amount of Radio Frequency (RF) chains for each beam. In addition, phase
shifter (PS) components used in this estimation need high power to select the beam in the desired direction.
To overcome these limitations, in this work, we propose Regular Scanning Support Detection (RSSD)
based channel estimation mechanism. Moreover, we utilise a 3D lens antenna array having metallic plate
and a switch in our model which compensates the limitation of phase shifters. Simulation results show that
the proposed RSSD based channel estimation surpasses traditional technique and SD based channel
estimation even in lower SNR area which is highly desirable in the millimeter wave (mmWave) massive
MIMO systems.
3D METALLIC PLATE LENS ANTENNA BASED BEAMSPACE CHANNEL ESTIMATION TECHNIQUE F...ijwmn
Beamspace channel estimation mechanism for massive MIMO (multiple input multiple output) antenna
system presents a major process to compensate the 5G spectrum challenges caused by the proliferation of
information from mobile devices. However, this estimation is required to ensure the perfect channel state
information (CSI) for lower amount of Radio Frequency (RF) chains for each beam. In addition, phase
shifter (PS) components used in this estimation need high power to select the beam in the desired direction.
To overcome these limitations, in this work, we propose Regular Scanning Support Detection (RSSD)
based channel estimation mechanism. Moreover, we utilise a 3D lens antenna array having metallic plate
and a switch in our model which compensates the limitation of phase shifters. Simulation results show that
the proposed RSSD based channel estimation surpasses traditional technique and SD based channel
estimation even in lower SNR area which is highly desirable in the millimeter wave (mmWave) massive
MIMO systems.
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.
This document discusses amplitude modulated communication systems. It describes how a carrier signal is modulated by a baseband modulating signal to allow for information exchange over a channel. There are different types of modulation including continuous wave, pulse, and digital modulation. Amplitude modulation varies the amplitude of the carrier signal based on the instantaneous value of the modulating signal. This allows for multiplexing of multiple messages and use of more practical antenna sizes. Specific amplitude modulation techniques are described like conventional AM, DSB-SC, SSB, and VSB along with their tradeoffs in terms of carrier suppression, bandwidth, cost, and applications.
In this paper, a new algorithm for a high resolution
Direction Of Arrival (DOA) estimation method for multiple
wideband signals is proposed. The proposed method proceeds
in two steps. In the first step, the received signals data is
decomposed in a Toeplitz form using the first-order statistics.
In the second step, The QR decomposition is applied on the
constructed Toeplitz matrix. Compared with existing schemes,
the proposed scheme provides several advantages. First, it
requires computing the triangular matrix R or the orthogonal
matrix Q to find the DOA; these matrices can be computed
with O(n2) operation. However, most of the existing schemes
required eignvalue decomposition (EVD) for the covariance
matrix or singular value decomposition (SVD) for the data
matrix; using EVD or SVD requires much more complex
computational O(n3) operation. Second, the proposed scheme
is more suitable for high-speed communication since it
requires first-order statistics and a single snapshot. Third,
the proposed scheme can estimate the correlated wideband
signals without using spatial smoothing techniques; whereas,
already-existing schemes do not. Accuracy of the proposed
wideband DOA estimation method is evaluated through
computer simulation in comparison with a conventional
method.
This document discusses multiple-input multiple-output (MIMO) systems, including their motivations and capabilities. MIMO systems use multiple antennas at both the transmitter and receiver to achieve high data rates approaching 1 Gbps while maintaining quality of service. The document covers MIMO channel models and capacity, design criteria like diversity and spatial multiplexing, practical architectures like V-BLAST and Alamouti's scheme, and applications to networking including MIMO-OFDM and MIMO MAC protocols.
This document discusses multi-carrier transmission over mobile radio channels. It introduces OFDM and MC-CDMA techniques for combating multipath interference in mobile channels. It describes various receiver designs for OFDM and MC-CDMA, including matrix inversion and decision feedback equalization approaches to estimate channel amplitudes and derivatives in order to reduce intercarrier interference caused by Doppler spread. Simulation results show performance improvements of these techniques over conventional OFDM.
In tech recent-advances_in_synthetic_aperture_radar_enhancement_and_informati...Naivedya Mishra
This document discusses recent advances in synthetic aperture radar (SAR) enhancement and information extraction. It summarizes three methods presented in the paper: 1) A wavelet-based despeckling and information extraction method using a Generalized Gauss-Markov Random Field (GGMRF) and Bayesian inference; 2) A method using GMRF and an Auto-binomial model with Bayesian inference; 3) A third method that also uses GMRF and an Auto-binomial model with Bayesian inference. The despeckling performance of these three methods is compared and texture parameter estimation is presented.
The document discusses the structure and characteristics of GPS signals. It covers topics like signal requirements, encoding methods, modulation techniques, and digital signal processing. Key points:
- GPS signals are transmitted from satellites on two carrier frequencies (L1 and L2) which are modulated by pseudo-random codes and navigation data.
- The signals use phase modulation to encode information in the carrier phase. Receivers use correlation and filtering techniques to recover the codes, data, and carrier signals.
- After the introduction of anti-spoofing in 1994, various methods like squaring, cross-correlation and Z-tracking were developed to still allow civilian use of the encrypted P-code signal.
QPSK , QAM AND FM MODULATION BY SDRbtp.pptxm8171611219
This document discusses communication using software-defined radio (SDR). It outlines several objectives for an SDR project including QPSK and QAM modulation schemes for audio and video transmission and reception. It describes generating bits, symbol synchronization, constellation diagrams, and MATLAB code for QPSK generation. It also discusses QAM modulation/demodulation, parameter estimation, error detection, and image/video transmission and reception using SDR hardware. Channel analysis techniques are presented including computing the channel matrix and analyzing multipath fading channels. Spectrum analysis of the channel is also described.
Similar to Mobile antennae general Beamforming principles presentation (20)
In the rapidly evolving landscape of technologies, XML continues to play a vital role in structuring, storing, and transporting data across diverse systems. The recent advancements in artificial intelligence (AI) present new methodologies for enhancing XML development workflows, introducing efficiency, automation, and intelligent capabilities. This presentation will outline the scope and perspective of utilizing AI in XML development. The potential benefits and the possible pitfalls will be highlighted, providing a balanced view of the subject.
We will explore the capabilities of AI in understanding XML markup languages and autonomously creating structured XML content. Additionally, we will examine the capacity of AI to enrich plain text with appropriate XML markup. Practical examples and methodological guidelines will be provided to elucidate how AI can be effectively prompted to interpret and generate accurate XML markup.
Further emphasis will be placed on the role of AI in developing XSLT, or schemas such as XSD and Schematron. We will address the techniques and strategies adopted to create prompts for generating code, explaining code, or refactoring the code, and the results achieved.
The discussion will extend to how AI can be used to transform XML content. In particular, the focus will be on the use of AI XPath extension functions in XSLT, Schematron, Schematron Quick Fixes, or for XML content refactoring.
The presentation aims to deliver a comprehensive overview of AI usage in XML development, providing attendees with the necessary knowledge to make informed decisions. Whether you’re at the early stages of adopting AI or considering integrating it in advanced XML development, this presentation will cover all levels of expertise.
By highlighting the potential advantages and challenges of integrating AI with XML development tools and languages, the presentation seeks to inspire thoughtful conversation around the future of XML development. We’ll not only delve into the technical aspects of AI-powered XML development but also discuss practical implications and possible future directions.
zkStudyClub - Reef: Fast Succinct Non-Interactive Zero-Knowledge Regex ProofsAlex Pruden
This paper presents Reef, a system for generating publicly verifiable succinct non-interactive zero-knowledge proofs that a committed document matches or does not match a regular expression. We describe applications such as proving the strength of passwords, the provenance of email despite redactions, the validity of oblivious DNS queries, and the existence of mutations in DNA. Reef supports the Perl Compatible Regular Expression syntax, including wildcards, alternation, ranges, capture groups, Kleene star, negations, and lookarounds. Reef introduces a new type of automata, Skipping Alternating Finite Automata (SAFA), that skips irrelevant parts of a document when producing proofs without undermining soundness, and instantiates SAFA with a lookup argument. Our experimental evaluation confirms that Reef can generate proofs for documents with 32M characters; the proofs are small and cheap to verify (under a second).
Paper: https://eprint.iacr.org/2023/1886
GridMate - End to end testing is a critical piece to ensure quality and avoid...ThomasParaiso2
End to end testing is a critical piece to ensure quality and avoid regressions. In this session, we share our journey building an E2E testing pipeline for GridMate components (LWC and Aura) using Cypress, JSForce, FakerJS…
DevOps and Testing slides at DASA ConnectKari Kakkonen
My and Rik Marselis slides at 30.5.2024 DASA Connect conference. We discuss about what is testing, then what is agile testing and finally what is Testing in DevOps. Finally we had lovely workshop with the participants trying to find out different ways to think about quality and testing in different parts of the DevOps infinity loop.
Observability Concepts EVERY Developer Should Know -- DeveloperWeek Europe.pdfPaige Cruz
Monitoring and observability aren’t traditionally found in software curriculums and many of us cobble this knowledge together from whatever vendor or ecosystem we were first introduced to and whatever is a part of your current company’s observability stack.
While the dev and ops silo continues to crumble….many organizations still relegate monitoring & observability as the purview of ops, infra and SRE teams. This is a mistake - achieving a highly observable system requires collaboration up and down the stack.
I, a former op, would like to extend an invitation to all application developers to join the observability party will share these foundational concepts to build on:
Why You Should Replace Windows 11 with Nitrux Linux 3.5.0 for enhanced perfor...SOFTTECHHUB
The choice of an operating system plays a pivotal role in shaping our computing experience. For decades, Microsoft's Windows has dominated the market, offering a familiar and widely adopted platform for personal and professional use. However, as technological advancements continue to push the boundaries of innovation, alternative operating systems have emerged, challenging the status quo and offering users a fresh perspective on computing.
One such alternative that has garnered significant attention and acclaim is Nitrux Linux 3.5.0, a sleek, powerful, and user-friendly Linux distribution that promises to redefine the way we interact with our devices. With its focus on performance, security, and customization, Nitrux Linux presents a compelling case for those seeking to break free from the constraints of proprietary software and embrace the freedom and flexibility of open-source computing.
GraphSummit Singapore | The Art of the Possible with Graph - Q2 2024Neo4j
Neha Bajwa, Vice President of Product Marketing, Neo4j
Join us as we explore breakthrough innovations enabled by interconnected data and AI. Discover firsthand how organizations use relationships in data to uncover contextual insights and solve our most pressing challenges – from optimizing supply chains, detecting fraud, and improving customer experiences to accelerating drug discoveries.
Alt. GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using ...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
Pushing the limits of ePRTC: 100ns holdover for 100 daysAdtran
At WSTS 2024, Alon Stern explored the topic of parametric holdover and explained how recent research findings can be implemented in real-world PNT networks to achieve 100 nanoseconds of accuracy for up to 100 days.
In his public lecture, Christian Timmerer provides insights into the fascinating history of video streaming, starting from its humble beginnings before YouTube to the groundbreaking technologies that now dominate platforms like Netflix and ORF ON. Timmerer also presents provocative contributions of his own that have significantly influenced the industry. He concludes by looking at future challenges and invites the audience to join in a discussion.
UiPath Test Automation using UiPath Test Suite series, part 5DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 5. In this session, we will cover CI/CD with devops.
Topics covered:
CI/CD with in UiPath
End-to-end overview of CI/CD pipeline with Azure devops
Speaker:
Lyndsey Byblow, Test Suite Sales Engineer @ UiPath, Inc.
Communications Mining Series - Zero to Hero - Session 1DianaGray10
This session provides introduction to UiPath Communication Mining, importance and platform overview. You will acquire a good understand of the phases in Communication Mining as we go over the platform with you. Topics covered:
• Communication Mining Overview
• Why is it important?
• How can it help today’s business and the benefits
• Phases in Communication Mining
• Demo on Platform overview
• Q/A
5. SDMA
Spatial Division MultipleAccess
---- Uses an array of antennas to provide control of space
by providing virtual channels in an angle domain
6. Directional Antennas
Sectorised antenna
1) switched beam system
•Use a number of fixed beams
•Select one of several beams to
enhance receive signals
2) adaptive array system
•Be able to change its antenna pattern
dynamically;
Smart antenna
7. System Model
Uniform LinearArray of M elements
c
d
c
l
sin
tfj c
etmtx 2
1 )()(
d
)(2
2 )()(
tfj c
etmtx
))1((2
))1(()(
Mtfj
M
c
eMtmtx
8. System Model
)()( tmtm
tfj c
etmtx 2
1 )()(
c
dj
etxtx
sin2
12 )()(
Narrow Band array processing Assumption:
c
dMj
M etxtx
sin)1(2
1 )()(
sin)1(2
sin22
sin2
1
c
c
c
d
Mj
d
j
d
j
e
e
e
S
Array response vector
9. System Model
The Beam-former Structure
)(
)()(
1
*
tXw
txwty
H
i
M
i
i
Mw
w
w
w
2
1
)(
)(
)(
)( 2
1
tx
tx
tx
tX
M
)(1 tx
)(2 tx
)(txM
1
2
M
*
1w
*
1w
*
Mw
)(ty
12. Optimum Beamformer Design
Maximum SINR beamformer
SRS
SR
w
NI
H
NI
SINR
1
1
max
Under different criterions
Mean-Square-Error optimum beamformer
2
)(tmEP
SPRwMMSE
1
13. Optimum Beamformer Design
Minimum-Variance-Distortionless-Response beamformer
SRS
SR
w HMVDR
1
1
Under different criterion
Maximum Likelihood optimal beamformer
SRS
SR
w
NI
H
NI
ML
1
1
14. Practical Issues
In practice, neither R nor RI+N is available to calculate the optimal
weights of the array;
In practice, direction of arrival (DOA) is also unknown.
Issues
Solution
Adaptive beamforming algorithms – the weights
are adjusted by some means using the available
information derived from the array output, array signal
and so on to make an estimation of the optimal weights;
DOA estimation methods
17. Adaptive Beamforming Algorithms
1. SMIAlgorithm (Sample Matrix Inverse)
N
i
H
iiN rr
N
R
1
1ˆ
Estimate R using N samples:
n
rr
R
n
n
R
H
nn
nn
1
ˆ1ˆ
nn
H
n
n
H
nnn
nn
rRrn
RrrR
R
n
n
R
1
1
1
1
1
11
1
1
ˆ)1(
)ˆˆ
ˆ1ˆ
,....2,1
0
ˆ 1
0
k
c
cIR
Use matrix inversion lemma:
Then:
SRw nn
1ˆ
18. Adaptive Beamforming Algorithms
2. LMS Algorithm (Least Mean Square)
**
1 )( nnnnn
H
nnnn erwdwrrww
nn
H
nn drwe
• Need training bits and calculate the error between the received
signal after beamforming and desired signal;
• The step size u decides the convergence of LMS algorithm;
• Based on how to choose u, we have a set of LMS algorithm,
“unconstraint LMS”, “normalized LMS”, “constraint LMS”.
According to orthogonality principle (data| error) of MMSE beamformer:
0)()()( *
tdwtrtrE H
Solution:
19. 3. RLS Algorithm (Recursive Least Square)
Adaptive Beamforming Algorithms
)()(ˆ *
1
1
1 nn
H
nnnn dwrrnRww
Given n samples of received signal r(t), consider the optimization
problem—minimize the cumulative square error
n
k
k
kn
e
0
2
min 10
Solution:
• In some situation LMS algorithm will converge with very slow
speed, and this problem can be solved with RLS algorithm.
20. Adaptive Beamforming Algorithms
4. CMA (Constant Modulus Algorithm)
Assume the desired signal has a constant modulus, the existence of an
interference causes fluctuation in the amplitude of the array output.
Consider the optimization problem:
2
2
2
)(
2
1
min AtrwE
H
Solution:
)( 2
2
1 Arwwrrww n
H
nn
H
nnnn
• This is a blind online adaptation, i.e., don’t need training bits
• CMA is useful for eliminating correlated arrivals with different magnitude
and is effective for constant modulated envelope signals such as GMSK
and QPSK
21. DOA Estimation Method
1. MFAlgorithm (Matched Filter)
2. MVDRAlgorithm
3. MUSICAlgorithm (MUltiple SIgnal Classification)
22. DOA Estimation Method
1. MF Algorithm (Matched Filter)
The total output power of the conventional beamformer is:
wRwwtrtrEwtrwEtyEP
H
H
HH
)()()()(
2
2
• The output power is maximized when
• The beam is scanned over the angular region say,(-900,900), in discrete
steps and calculate the output power as a function of AOA
• The output power as a function of AOA is often termed as the spatial
spectrum
• The DOA can be estimated by locating peaks in the spatial spectrum
• This works well when there is only one signal present
• But when there is more than one signal present, the array output power
contains contribution from the desired signal as well as the undesired
ones from other directions, hence has poor resolution
0Sw
23. 2. MVDR Algorithm
DOA Estimation Method
This technique form a beam in the desired look direction while taking into
consideration of forming nulls in the direction of interfering signals.
wRwtyE
H
min)(min
2
1Swtosubject
H
Solution:
SRS
P HMVDR
1
1
)(
• By computing and plotting pMVDR over the whole angle range, the DOA’s
can be estimated by locating the peaks in the spectrum
• MVDR algorithm provides a better resolution when compared to MF
algorithm
• MVDR algorithm requires the computation of a matrix inverse, which can
be expensive for large arrays
24. DOA Estimation Method
Comparison of resolution performance of MF and MVDR algorithms
Scenario: Two signals of equal power at SNR of 20dB arrive at a 6-element uniformly
spaced array at angles 90 and 100 degrees, respectively
25. 3. MUSIC Algorithm (MUltiple SIgnal Classification)
DOA Estimation Method
MUSIC is a high resolution multiple signal classification technique based
on exploiting the eigenstructure of the input covariance matrix.
Step 1: Collect input samples and estimate the input covariance matrix
N
i
H
ii rr
N
R
1
1ˆ
Step 2: Perform eigen decomposition
VVRˆ
},,,{ 21 Mdiag M 21
MqqqV ,,, 21
26. 3. MUSIC Algorithm (MUltiple SIgnal Classification)
DOA Estimation Method
Step 3: Estimate the number of signals based on the fact :
DMK ˆ
• The first K eigen vectors represent the signal subspace, while the last
M-K eigen vectors represent the noise subspace
• The last M-K eigen values are equal and equal to the noise variance
find the D smallest eigen values that almost equal to each other
Step 4: Compute the MUSIC spectrum
SVVS
P
H
nn
HMUSIC
1
)( MKKn qqqV ,,, 21
find the largest peaks of Pmusic to obtain estimates of DOAKˆ
27. DOA Estimation Method
Comparison of resolution performance of MVDR and MUSIC
Scenario: Two signals of equal power at SNR of 20dB arrive at a 6-element uniformly
spaced array at angles 90 and 95 degrees, respectively
28. Summary of Part I
• System model
• Optimum beamformer design
• Adaptive beamforming algorithms
1) SMI
2) LMS
3) RLS
4) CMA
• DOA estimation method
1) MF
2) MVDR
3) MUSIC
29. Part II: Schemes using directional antennas
in MAC layer of ad hoc network
31. RTS/CTS mechanism in 802.11
Nodes are assumed to transmit using omni-directional antennas.
Both RTS and CTS packet contain the proposed duration of data
transmission
The area covered by the transmission range of both the sender(node B) and
the receiver (node C) is reserved during the data transfer
This mechanism reduce collisions due to the hidden terminal problem
However, it waste a large portion of network capacity.
32. Vaidya Scheme 1
Assumption:
Each node knows its exact location and the location of its neighbors
Each node is equipped with directional antennas
If node X received RTS or CTS related to other nodes, then node X will
not transmit anything in that direction until that other transfer is
completed
That direction or antenna element would be said to be “blocked”
While one directional at some node be blocked, other directional at the
same nodes may not be blocked, allowing transmission using the
unblocked antenna
33. Vaidya Scheme 1
A B C D E
DRTS
OCTS
OCTS
DATA
ACK
DRTS
OCTS
DATA
ACK
OCTS
34. Vaidya Scheme 1
Utilize a directional antenna for sending the RTS (DRTS), whereas
CTS are transmitted in all directions (OCTS).
Data andACK packets are sent directionally.
Any other node that hears the OCTS only blocks the antenna on
which the OCTS was received.
36. Vaidya Scheme 2
A node uses two types RTS packets: DRTS and ORTS according to the
following rules:
1) if none of the directional antennas at node X are blocked, then node X
will send ORTS;
2) otherwise, node X will send a DRTS provided that the desired
directional antenna is not blocked.
37. A B C D
ORTS
OCTS
OCTS
DATA
ACK
Vaidya Scheme 2
F
ORTS
DRTS
40. Nasipuri Scheme
NodeA that wishes to send a data packet to B first sends an omni-
directional RTS packet
Node B receives RTS correctly and responds by transmitting a CTS
packet, again on all directions.
In the meanwhile, B can do DOA estimation from receiving RTS packet
Similarly, node A estimates the direction of B while receiving the CTS
packet.
Then node A will proceed to transmit the data packets on the antenna
facing the direction of B.
43. Bagrodia Scheme
DirectionalVirtual Carrier Sensing(DVCS)
Three primary capabilities are added to original 802.11 MAC protocol for
directional communication with DVCS:
1) caching theAngle ofArrival (AOA)
2) beam locking and unlocking
3) the use of Directional NetworkAllocationVector (DNAV)
44. Bagrodia Scheme
1.AOA caching
Each node caches estimatedAOAs from neighboring nodes whenever it
hears any signal, regardless of whether the signal is sent to it or not
When node X has data to send, it searches its cache for theAOA
information, if theAOA is found, the node will send a directional RTS,
otherwise, the RTS is send omni-directionally.
The node updates itsAOA information each time it receives a newer
signal from the same neighbor.
It also invalidates the cache in case if it fails to get the CTS after 4
directional RTS transmission.
45. Bagrodia Scheme
2. Beam locking and unlocking
A B
B
(1)RTS
(2)CTS(3)Data
(4)ACK
When a node gets an RTS, it locks its beam pattern
towards the source to transmit CTS
The source locks the beam pattern after it receives CTS .
The beam patterns at both sides are used for both
transmission and reception, and are unlocked after ACK is
completed.
46. Bagrodia Scheme
3. DNAV setting
DNAV is a directional version of NAV(used in the original 802.11
MAC), which reserves the channel for others only in a range of
directions.
Available directions for transmission
In the fig:
Three DNAVs are set up
towards 300, 750 and 3000 with
600 width.
Until the expiration of these
DNAVs, this mode cannot
transmit any signals with
direction between 0-1050 or
270-3300 , but is allowed to
transmit signals towards 105-
2700 and 330-3600
47. Bagrodia Scheme
A network situation where DVCS can improve the network
capacity with DNAVs
F
BD
E
A C
49. Summary of Part II
Comparison of four schemes
RTS CTS Data ACK
802.11 omni omni omni omni
Vaidya 1 dir. omni dir. dir.
Vaidya 2 dir./omni omni dir. dir.
Nasipuri omni omni dir. dir.
Bagrodia dir./omni dir. dir. dir.
50. Conclusion
smart antenna is a technology for wireless systems that use a set of antenna
elements in an array.The signal from these antenna elements are combined
to form a movable beam pattern that can be steered to a desired direction
smart antennas enable spatial reuse and they increase the communication
range because of the directivity of the antennas
smart antennas can be beneficial for wireless ad hoc networks to enhance
the capacity of the network
To best utilize directional antennas, a suitable MAC protocol must be
designed
If the locations are unknown , DOA estimation may be needed before
sending directional signals
51. reference
LiliWei 2002 presentation on smart antennae
J.C.Liberti,T.S.Rappaport, “Smart antennas for wireless communications: IS-95 and
third generation CDMA applications”
L.C.Godara, “Application of antenna arrays to mobile communicaitions, part I:
performance improvement, feasiblility, and system considerations”
L.C.Godara, “Application of antenna arrays to mobile communications, part II: beam-
forming and direction-of-arrival considerations”
Y.b Ko,V.Shankarkumar and N.Vaidya, “Medium access control protocols using
directional antennas in ad hoc networks”
A.Nasipuri, S.Ye, J.You and R.Hiromoto, “A MAC protocol for mobile ad hoc networks
using directional antennas”
M.Takai, J.Martin,A.Ren and R.Bagrodia, “Directional virtual carrier sensing for
directional antennas in mobile ad hoc networks”
S.Bellofiore, J.Foutz, etc.. “Smart antenna system analysis, integration and performance
for mobile ad-hoc networks (MANETs)