Single Data Stream Research Articles

Coverage Analysis of Multi-Stream MIMO HetNets With MRC Receivers

Most of the current research on the coverage performance of multi-stream MIMO heterogeneous networks (HetNets) has focused on a single data-stream. This does not always provide accurate results as our analysis show the cross-stream correlation due to interference can greatly affect the coverage performance. This paper analyzes the coverage probability in such systems, and studies the impact of cross-stream correlation. Specifically, we focus on the max-SIR cell association policy and leverage stochastic geometry to study scenarios, whereby a receiver is considered in the coverage, if all of its data-streams are successfully decodeable. Assuming open-loop maximum ratio combining (MRC) at receivers, we consider the cases where partial channel state information is available at the receiver. We then obtain an upper-bound on the coverage and formulate cross-stream SIR correlation. We further show that approximating such systems based on fully-correlated (non-correlated) data-streams results in a slight underestimation (substantial overestimation) of the coverage performance. Our results provide insights on the multiplexing regimes where densification improves the coverage performance and spectral efficiency. We also compare MRC with more complex zero-forcing receiver and provide quantitative insights on the design tradeoffs. Our analysis is validated via extensive simulations.

Sub Carrier Analysis for QAM Modulation

Orthogonal Frequency Division Multiplexing (OFDM) based wireless data transmission system is a multi-carrier system in which single higher rate data stream can be divided into multiple lower rate data streams. Modulation and De-Modulation technique play a major role in OFDM based data transmission system. Based on Modulation technique only, the frequency transformation method and encoding and decoding methods are enabled. Effective modulation techniques called as “Quadrature Amplitude Modulation (QAM)” modulation are used to design an OFDM System. Carrier signal is one of the important signals used to modulate the original signal. Analyzing the sub-carrier signal for getting the quality of the modulated signal.

Big Data in the Era of Health Information Exchanges: Challenges and Opportunities for Public Health

Public health surveillance of communicable diseases depends on timely, complete, accurate, and useful data that are collected across a number of healthcare and public health systems. Health Information Exchanges (HIEs) which support electronic sharing of data and information between health care organizations are recognized as a source of ‘big data’ in healthcare and have the potential to provide public health with a single stream of data collated across disparate systems and sources. However, given these data are not collected specifically to meet public health objectives, it is unknown whether a public health agency’s (PHA’s) secondary use of the data is supportive of or presents additional barriers to meeting disease reporting and surveillance needs. To explore this issue, we conducted an assessment of big data that is available to a PHA—laboratory test results and clinician-generated notifiable condition report data—through its participation in a HIE.

Merging fluxgate and induction coil data to produce low-noise geomagnetic observatory data meeting the INTERMAGNET definitive 1 s data standard

Abstract. For frequencies above 30 mHz the instrument intrinsic noise level of typical fluxgate magnetometers used at geomagnetic observatories usually masks ambient magnetic field variations on magnetically quiet days. This is especially true for stations located at middle and low latitudes, where variations are generally smaller than at high latitudes. INTERMAGNET has set a minimum quality standard for definitive 1 s data. Natural field variations referred to as pulsations (Pc-1, Pc-2, Pi-1) fall in this band. Usually their intensity is so small that they rarely surpass the instrumental noise of fluxgate magnetometers. Moreover, high-quality magnetic field observations in the band 30 mHz–0.5 Hz contain interesting information, e.g., for the study of ionospheric electron interactions with electromagnetic ion cyclotron plasma waves. We propose a method to improve 1 Hz observatory data by merging data from the proven and tested fluxgate magnetometers currently in use with induction coil magnetometers into a single data stream. We show how measurements of both instruments can be combined without information loss or phase distortion. The result is a time series of the magnetic field vector components, combining the benefits of both instruments: long-term stability (fluxgate) and low noise at high frequencies (induction coil). This new data stream fits perfectly into the data management procedures of INTERMAGNET and meets the requirements defined in the definitive 1 s data standard. We describe the applied algorithm and validate the result by comparing power spectra of the fluxgate magnetometer output with the merged signal. Daily spectrograms from the Niemegk observatory show that the resulting data series reveal information at frequencies above 30 mHz that cannot be seen in raw fluxgate data.

Transceiver Optimization for Two-Hop MIMO Relay Systems With Direct Link and MSE Constraints

In this paper, we investigate the transceiver design in a two-hop amplify-and-forward (AF) multiple-input multiple-output (MIMO) relay system with the direct link and quality-of-service (QoS) constraint. The QoS criterion is specified by the upper bound of the mean-squared error of the signal waveform estimation at the destination node. To minimize the total system transmission power, we apply a new AF relay protocol where the source node transmits signals during both time slots. Two iterative algorithms are proposed to jointly optimize the source and relay precoding matrices for the general case with multiple concurrent data streams, and the special case where a single data stream is transmitted, respectively. Simulation results show the effectiveness of both proposed algorithms. Interestingly, for the single data stream case, the second algorithm converges faster than the first algorithm. Compared with conventional two-hop MIMO relay systems where the source node is silent at the second time slot, the new protocol reduces the system transmission power. Under a given system transmission power, the proposed algorithms yield a higher system mutual information thanks to a better utilization of the direct link. Simulation results in this paper shed lights on some fundamental questions in relay system design such as when direct communication between source and destination (without any relay nodes) is optimal, and when the new AF relay protocol provides a larger gain compared with the conventional single phase source power allocation.

New Results on Transceiver Design for Two-Hop Amplify-and-Forward MIMO Relay Systems With Direct Link

Conventional amplify-and-forward (AF) protocol for half-duplex two-hop multiple-input-multiple-output (MIMO) relay systems assumes that the source node transmits the signal only at the first time slot. While making the source node silent at the second time slot simplifies the system design, it is strictly suboptimal. To improve the system performance, in this paper, we consider that the source node transmits signals during both time slots. We develop two novel iterative algorithms to optimize the source, relay, and receiver matrices in this new AF MIMO relay system. Both algorithms are based on the minimum mean-square error (MMSE) criterion. In particular, the first algorithm is applicable for general MIMO relay systems with multiple concurrent data streams, where the source, relay, and receiver matrices are optimized in an alternating fashion until convergence. The second algorithm is developed for MIMO relay systems with a single data stream, where the source precoding vectors and the relay precoding matrix are optimized iteratively and the receiver matrix is obtained after the convergence of the source vectors and the relay matrix. Simulation results show that compared with conventional AF MIMO relay systems, the proposed system provides better bit-error-rate performance for both multiple-data-stream and single-data-stream cases.

Performance Evaluation of Matrix-Matrix Multiplications Using Intel's Advanced Vector Extensions (AVX)

Intel's Advanced Vector Extensions is known as single instruction multiple data streams (SIMD), and the instruction sets is introduced in the second-generation Intel Core processor family. This new technology is supported by new generations of Intel and AMD processors. The advanced vector extensions (AVX) exploits single instruction multiple data (SIMD) computing units for fine grained-parallelism. These instructions process multiple data elements simultaneously and independently. Many applications such as signal processing, recognition, visual processing, scientific and engineering numerical, physics and other areas of applications need for vector floating point performance supported by AVX. Matrix-Matrix multiplications is the core of many important algorithms such as signal processing, scientific and engineering numerical, so it is substantial to accelerate implementation of matrix-matrix multiplications. It is very important to use appropriate compilers that can optimally utilize the new features of the evolving processors. For this purpose, a clear vision on the performance of the compilers on performance characteristics of AVX is needed. In addition choosing the appropriate programming method is substantial to gain the best performance. In this paper, the performance evaluation of matrix-matrix multiplications in three forms (C=A. B, C=A. BT, and C=AT. B), using Intel's advanced vector extension (AVX) instruction sets has been reported. The obtained results are compared using inline assembly versus intrinsic functions for programming. A comparative study to indicate the effects of two widely used C++ compilers: Intel C++ compiler (ICC) in Intel Parallel Studio XE 2016 against Microsoft Visual Studio C++ compiler 2015 (MSVC++) has been investigated. The results are evaluated on Intel Core i7 processor on a Broadwell system for square matrices of different large sizes. The results demonstrate that the Intel compiler has better performance than MSVC++ compiler by 1.34, 1.32, and 1.22 using inline assembly language and by 1.36, 1.19, and 1.25 using intrinsic functions for C=A. B, C=A. BT, and C=AT. B, respectively. The performance of using intrinsic functions compared to the inline assembly demonstrates that the intrinsic functions has better performance than inline assembly by 2.1, 2.13, and 2.18 using Intel compiler and by 2.08, 2.49, and 2.11 using MSVC++ compiler for C=A. B, C=A. BT, and C=AT. B, respectively.

Design and Performance Analysis of Noncoherent Detection Systems With Massive Receiver Arrays

Harvesting the gain of a large number of antennas in a mmWave band has mainly been relying on the costly operation of channel state information (CSI) acquisition and cumbersome phase shifters. Recent works have started to investigate the possibility to use receivers based on energy detection (ED), where a single data stream is decoded based on the channel and noise energy. The asymptotic features of the massive receiver array lead to a system where the impact of the noise becomes predictable due to a noise hardening effect. This in effect extends the communication range compared to the receiver with a small number of antennas, as the latter is limited by the unpredictability of the additive noise. When the channel has a large number of spatial degrees of freedom, the system becomes robust to imperfect channel knowledge due to channel hardening. We propose two detection methods based on the instantaneous and average channel energy, respectively. Meanwhile, we design the detection thresholds based on the asymptotic properties of the received energy. Differently from existing works, we analyze the scaling law behavior of the symbol-error-rate (SER). When the instantaneous channel energy is known, the performance of ED approaches that of the coherent detection in high SNR scenarios. When the receiver relies on the average channel energy, our performance analysis is based on the exact SER, rather than an approximation. It is shown that the logarithm of SER decreases linearly as a function of the number of antennas. Additionally, a saturation appears at high SNR for PAM constellations of order larger than two, due to the uncertainty on the channel energy. Simulation results show that ED, with a much lower complexity, achieves promising performance both in Rayleigh fading channels and in sparse channels.

Study of statistical properties of hybrid statistic in coherent multidetector compact binary coalescences search

In this article, we revisit the problem of coherent multi-detector search of gravitational wave from compact binary coalescence with Neutron stars and Black Holes using advanced interferometers like LIGO-Virgo. Based on the loss of optimal multi-detector signal-to-noise ratio (SNR), we construct a hybrid statistic as a best of maximum-likelihood-ratio(MLR) statistic tuned for face-on and face-off binaries. The statistical properties of the hybrid statistic is studied. The performance of this hybrid statistic is compared with that of the coherent MLR statistic for generic inclination angles. Owing to the single synthetic data stream, the hybrid statistic gives low false alarms compared to the multi-detector MLR statistic and small fractional loss in the optimum SNR for a large range of binary inclinations. We have demonstrated that for a LIGO-Virgo network and binary inclination, \epsilon < 70 deg. and \epsilon > 110 deg., the hybrid statistic captures more than 98% of network optimum matched filter SNR with low false alarm rate. The Monte-Carlo exercise with two distributions of incoming inclination angles namely, U[cos(\epsilon)] and more realistic distribution proposed by B. F. Schutz are performed with hybrid statistic and gave ~5% and ~7% higher detection probability respectively compared to the two stream multi-detector MLR statistic for a fixed false alarm probability of 10^-5.

Robust beamforming with block diagonalisation for MIMO interference channels

The authors focus on robust beamforming design for multiple-input multiple-output (MIMO) interference channels with imperfect channel state information (CSI) which is described as a bounded CSI error model. With all transmissions restricted to single data stream, the problem of maximising the minimum signal-to-inference-plus-noise ratio (SINR) subject to individual power constraint at each transmitter is considered as the max–min fairness transceiver design. Specifically, the authors propose a robust beamforming algorithm named as block diagonalisation assisted (BDA) approach for solving the max–min problem. First, block diagonalisation precoding is applied to simplify the original max–min SINR problem. Then, an iterative algorithm is proposed with alternating process to solve the simplified problem, and the convergence behaviour and computational complexity are analysed. Simulation results show the convergence of the BDA algorithm and demonstrate the robustness of the proposed transceiver design through the bit error rate and the minimum SINR.

On multi-frequency channel interference alignment of 3 channels and 4 users

This paper explores the multi-frequency independent channel interference alignment (MFC-IA) system of 3 channels and 4 users, and single data stream transmit, i.e. (3×3,1)4 system. We derive the analytic solution for (3×3,1)4 MFC-IA system. Based on the analytic solution, an optimization problem is proposed aim at the optimal IA solution. Then based on such a math model, we propose a simulated annealing (SA) algorithm to search optimal IA solution. The simulation results show that the simulated annealing IA algorithm has a better sum rate performance than iterative maximize signal to interference plus noise ratio (Max-SINR) algorithm. This result can be extended to single data stream multi-antenna IA system with 3 antennas and 4 users.

Equivalence and generalization in a layered network model

We propose a formal model of layered telecommunication networks. The model includes ports, which are access points to data streams; links, which transmit data streams; and adapters, which convert data streams from one layer to another. Two ports communicate if there is a path from one to the other in which every adaptation is balanced by a reverse adaptation. Two networks M and N with the same public ports are equivalent if for any other network Q, two ports in the composition M∘Q communicate exactly if they communicate in N∘Q. M generalizes N if whenever two ports communicate in N∘Q, the ports also communicate in M∘Q. We give linear time algorithms to decide equivalence and generalization of networks when adaptation is “simple”, i.e. one or more data streams can be adapted into only a single data stream. If adaptation models “protection switching,” then testing equivalence is co-NP-complete.

Block Markov Superposition Transmission of Short Codes for Indoor Visible Light Communications

This letter presents a coded modulation scheme for indoor visible light communication (VLC), which is based on the recently proposed coding scheme called block Markov superposition transmission (BMST). As the bandwidth of a single light-emitting-diode (LED) light is limited, we use parallel LED wicks to transmit simultaneously multiple coded bit-streams, resembling a multiple access system. At the transmitter, a single stream of data is first encoded by a properly designed BMST encoder and then partitioned equally into multiple streams, each of which, in the case of no precoding, is used to drive an LED wick in an on-off keying (OOK) manner. With a tailored power-allocation scheme, the noise-free received signals can form an equispaced pulse amplitude modulation (PAM) constellation. Also proposed is the use of precoding to achieve Gray mapping, which plays an important role in reducing complexity without degrading performance since no iterative processing is required between the detection and the decoding. Simulation results show that the proposed scheme achieves a significant coding gain.

A Survey of Paradigms for Building and Designing Parallel Computing Machines

In this paper we describe paradigms for building and designing parallel computing machines. Firstly we elaborate the uniqueness of MIMD model for the execution of diverse applications. Then we compare the General Purpose Architecture of Parallel Computers with Special Purpose Architecture of Parallel Computers in terms of cost, throughput and efficiency. Then we describe how Parallel Computer Architecture employs parallelism and concurrency through pipelining. Since Pipelining improves the performance of a machine by dividing an instruction into a number of stages, therefore we describe how the performance of a vector processor is enhanced by employing multi pipelining among its processing elements. Also we have elaborated the RISC architecture and Pipelining in RISC machines After comparing RISC computers with CISC computers we observe that although the high speed of RISC computers is very desirable but the significance of speed of a computer is dependent on implementation strategies. Only CPU clock speed is not the only parameter to move the system software from CISC to RISC computers but the other parameters should also be considered like instruction size or format, addressing modes, complexity of instructions and machine cycles required by instructions. Considering all parameters will give performance gain . We discuss Multiprocessor and Data Flow Machines in a concise manner. Then we discuss three SIMD (Single Instruction stream Multiple Data stream) machines which are DEC/MasPar MP-1, Systolic Processors and Wavefront array Processors. The DEC/MasPar MP-1 is a massively parallel SIMD array processor. A wide variety of number representations and arithmetic systems for computers can be implemented easily on the DEC/MasPar MP-1 system. The principal advantages of using such 64×64 SIMD array of 4-bit processors for the implementation of a computer arithmetic laboratory arise out of its flexibility. After comparison of Systolic Processors with Wave front Processors we found that both of the Systolic Processors and Wave front Processors are fast and implemented in VLSI. The major drawback of Systolic Processors is the problem of availability of inputs when clock ticks because of propagation delays in connection buses. The Wave front Processors combine the Systolic Processor architecture with Data Flow machine architecture. Although the Wave front processors use asynchronous data flow computing structure, the timing in the interconnection buses, at input and at output is not problematic..

Peer-assisted multimedia delivery using periodic multicast

Multimedia content distribution is one of the most popular services available on the Internet, and several approaches have been developed to satisfy user requirements and reduce server load. IP multicast is one efficient mechanism for distributing content to multiple users with minimal server and network loads. Because its single stream of data is transmitted simultaneously to multiple users, IP multicast is well-suited for real-time broadcasting. However, it is difficult to offer on-demand multimedia services with IP multicast in which users request content without synchronization. In this paper, we propose an on-demand based multimedia delivery system using IP multicast. In our system, the multimedia server starts multicasting content upon receiving the first content request. Subsequent users then join the multicast session at any time during the transmission. The content that subsequent users have missed is provided by the users (peers) that joined earlier, or by server unicasts. To minimize server load, we quantitatively analyzed the optimal multicast starting point. Through simulation, we show that our proposed system outperforms prior related systems based on peer-to-peer delivery and multicasting.

On the Organization of Parallel Operation of Some Algorithms for Finding the Shortest Path on a Graph on a Computer System with Multiple Instruction Stream and Single Data Stream

On the Organization of Parallel Operation of Some Algorithms for Finding the Shortest Path on a Graph on a Computer System with Multiple Instruction Stream and Single Data Stream

A parallel FPGA implementation for real-time 2D pixel clustering for the ATLAS Fast Tracker Processor

The parallel 2D pixel clustering FPGA implementation used for the input system of the ATLAS Fast TracKer (FTK) processor is presented. The input system for the FTK processor will receive data from the Pixel and micro-strip detectors from inner ATLAS read out drivers (RODs) at full rate, for total of 760Gbs, as sent by the RODs after level-1 triggers. Clustering serves two purposes, the first is to reduce the high rate of the received data before further processing, the second is to determine the cluster centroid to obtain the best spatial measurement. For the pixel detectors the clustering is implemented by using a 2D-clustering algorithm that takes advantage of a moving window technique to minimize the logic required for cluster identification. The cluster detection window size can be adjusted for optimizing the cluster identification process. Additionally, the implementation can be parallelized by instantiating multiple cores to identify different clusters independently thus exploiting more FPGA resources. This flexibility makes the implementation suitable for a variety of demanding image processing applications. The implementation is robust against bit errors in the input data stream and drops all data that cannot be identified. In the unlikely event of missing control words, the implementation will ensure stable data processing by inserting the missing control words in the data stream. The 2D pixel clustering implementation is developed and tested in both single flow and parallel versions. The first parallel version with 16 parallel cluster identification engines is presented. The input data from the RODs are received through S-Links and the processing units that follow the clustering implementation also require a single data stream, therefore data parallelizing (demultiplexing) and serializing (multiplexing) modules are introduced in order to accommodate the parallelized version and restore the data stream afterwards. The results of the first hardware tests of the single flow implementation on the custom FTK input mezzanine (IM) board are presented. We report on the integration of 16 parallel engines in the same FPGA and the resulting performances. The parallel 2D-clustering implementation has sufficient processing power to meet the specification for the Pixel layers of ATLAS, for up to 80 overlapping pp collisions that correspond to the maximum LHC luminosity planned until 2022.

Investigation of Modulators in OTDM System

With the ever-increasing demand for higher speeds and larger capacity brought about by rapid data growth on the Internet, interest in optical time division multiplexing has been growing rapidly in recent years due to its high speed and ability to overcome the “electronic bottleneck” offered by today’s electronic components. Optical time division multiplexing (OTDM) transmits multiple data channels in the form of ultra-short duration optical pulses which are interleaved into a single high-speed data stream by accurate control of their relative delay in the time domain. OTDM transmission system has been a topic of continuous research due to their unique advantages over conventional Pulse sources based transmissions. Among various key high repetition rate, limited pulse source, pulse range still remains as the issues that require further optimization. The performance of OTDM system is analyzed by using BER analyzer in which Q factor is to be measured. In OTDM system the maximum Q factor can be achieved by using different methods which are increasing laser power, using various.. We will focus on performance metrics and parameters used in the topology. We also focused on various modulators related to the topology.

Исследование производительности процессора обработки структур в системе с многими потоками команд и одним потоком данных

Исследование производительности процессора обработки структур в системе с многими потоками команд и одним потоком данных

Degrees of Freedom of MIMO-MAC with Random Access

A distributed random access network with K users and one Access Point (AP) is considered. It is assumed that users and the AP are equipped with M and N antennas, respectively. Each user independently decides whether to transmit in a time slot or not. We initially focus on two-user random access networks and characterize the network average Degrees of Freedom (DoF)1. For the K-user networks, an upper-bound on the network average DoF is first proposed. Then, it is shown that the proposed upper-bound can be achieved using single stream data transmission for many network configurations. Finally, we show through a few examples that there exist some network configurations where multi-stream data transmission in conjunction with interference alignment is necessary in order to achieve the upper-bound.