Burst Communication Research Articles

Research on Frequency Estimation Based on LS-SVC in Unknown Noise

When noise model is already known, maximum likelihood estimator (MLE) is asymptotically the most optimum one. However, the truth is just the opposite that, noise is unknown in burst communication systems. Aiming that, this paper utilizes the transmitted symbols of burst communications which are eliminated firstly in common methods and proposes a data-aided (DA) frequency estimation algorithm based on least squares support vector classification (LS-SVC). By researching on statistical learning theory (SLT), we construct a structural risk minimization (SRM) function with respect to frequency, and convert the estimation problem into deriving the extremum value of a classification function. Consequently, support vector classification (SVC)’s good learning and generalization capabilities are completely explored and employed. Experimental results show that the proposed algorithm is close to MLE in the case of Gaussian noise, and also exhits good performance in non-Gaussian condition. 

Proposal of Go-Back-i-symbol ARQ Scheme and its Performance Evaluation in Meteor Burst Communications

In this paper, we propose a new automatic repeat request (ARQ) scheme, named Go-Back-i-symbol (GBi) ARQ scheme, suitable to Meteor Burst Communications (MBC). The scheme realizes symbol-wise ARQ by using the Viterbi decoding algorithm for convolutional codes. We also propose a practical transmission protocol for applying the GBi-ARQ scheme to packet communications over time varying short burst channels such as meteor burst channels. Fundamental performances of the GBi-ARQ scheme in MBC are evaluated by computer simulations. Effectiveness of the GBi-ARQ scheme is shown by comparing the performance with that of a conventional block-wise ARQ scheme.

Global variation of meteor trail plasma turbulence

Abstract. We present the first global simulations on the occurrence of meteor trail plasma irregularities. These results seek to answer the following questions: when a meteoroid disintegrates in the atmosphere, will the resulting trail become plasma turbulent? What are the factors influencing the development of turbulence? and how do these trails vary on a global scale? Understanding meteor trail plasma turbulence is important because turbulent meteor trails are visible as non-specular trails to coherent radars. Turbulence also influences the evolution of specular radar meteor trails; this fact is important for the inference of mesospheric temperatures from the trail diffusion rates, and their usage for meteor burst communication. We provide evidence of the significant effect that neutral atmospheric winds and ionospheric plasma density have on the variability of meteor trail evolution and on the observation of non-specular meteor trails. We demonstrate that trails are far less likely to become and remain turbulent in daylight, explaining several observational trends for non-specular and specular meteor trails.

A Parallel Timing Adjustment Algorithm for High Speed Wireless Burst Communication

A zig-zag Gardner algorithm with parallel architecture is presented in this letter. This algorithm performs timing adjustment in each individual burst independently for high speed wireless burst communication with a short guard. Over sampling data are stored in RAM initially and read forward and backward alternately later. The proposed algorithm has distinct symmetric characteristic in the forward and backward process, which makes the alternate sequences achieve nearly the same effect as a continuous sequence. The performance of the proposed algorithm is very close to the theoretical curve.

An adaptive receiver of joint data and channel estimation for meteor burst communications

AbstractIn view of the characteristics of the meteor burst channel, the variable rate data transmission should be adopted to improve the system average throughput, which results in channel tracing and equalization problems at the receiver. Although the joint data and channel estimation of maximum likelihood sequence detection performing the principle of per‐survivor processing (PSP) is considered as an optimal detection scheme, its great computational complexity is a major problem and can hardly agree with the decreasing of the meteor channel. Based on the estimation of the system parameters, an adaptive state reduction of the PSP (ASRP) algorithm with only a few states in the trellis diagram is employed, while these states are chosen by the time‐varying threshold according to the exponential decay of meteor channels. It is shown that, ASRP can make a good tradeoff between the performance and the computational complexity, and provides reliable data transmission for adaptive modulation and coding of the meteor burst communication system. Computer simulation results and performance analysis are also included to support our developments. Copyright © 2010 John Wiley & Sons, Ltd.

Burst communication by means of buffer allocation in body sensor networks: Exploiting signal processing to reduce the number of transmissions

Monitoring human movements using wireless sensory devices promises to revolutionize the delivery of healthcare services. Such platforms use inertial information of their subjects for motion analysis. Potentially, each action or disease can be discovered by collaborative processing of sensor data from multiple locations on the body. This functionality is provided by a Body Sensor Network (BSN), which consists of several wireless sensor nodes positioned on different parts of the body. In spite of the revolutionary potential of this platform, power requirements and wearability have limited the commercialization of these systems. In this paper, we present an energy-efficient communication model for BSN applications which uses buffers to limit communication to short bursts, decreasing power usage and simplifying the communication. We formulate an optimization problem to reduce transmissions among sensor nodes and present an ILP-based solution and a fast greedy heuristic algorithm. We show that despite the decreased transmission efficiency, our greedy algorithm can be adopted for fast allocation of buffers in real-time. We experimentally compare the performance of both of the proposed approaches to the performance of an unbuffered system. Our results demonstrate that ILP and greedy solutions can reduce the amount of transmissions by an average factor of 70 and 41, respectively.

Diurnal Variability Prediction Model of Meteor Burst Communication Channel

流星突发通信不同于传统的通信, 其是低速率通信, 具有突发、不连续、不定时的特性. 因此, 流星余迹通信的复杂性要求有必要对其通信信道进行建模. 在流星通信链路中, 流星的辐射分布、可用流星率和占空比是影响流星通信信道性能的重要参数. 流星辐射分布在不同季节不同时间都各不相同, 因此准确预测流星通信链路在不同时间的流星辐射分布, 从而改变大圆路径上天线的指向, 对提高通信速率显得非常重要. 同时, 准确预测流星突发通信链路上的可用流星率和占空比, 有助于准确预测并建立流星突发信道模型. 本文分析研究了偶发流星辐射分布建模的发展, 建立了偶发流星日心空间和地心空间的几何关系, 得到了流星突发通信信道参数预测模型. 并将预测模型应用于流星通信链路, 预测结果与通信链路观测结果比较一致, 为流星通信系统的建立提供了技术支持.

Semi-Irregular LDPC Codes Used in MBC

Based on the channel properties of of the meteor burst communication, a kind of semi-irregular LDPC codes suitable for MBC is presented. Simulation results show that the application of this kind of semi-irregular LDPC codes in MBC yields better performance than the regular ones. Some theoretical analyses are given.

Master Interface for On-chip Hardware Accelerator Burst Communications

We explain a systematic way of interfacing data-flow hardware accelerators (IP) for their integration in a system on chip. We abstract the communication behaviour of the data flow IP so as to provide basis for an interface generator. Then we measure the throughput obtained for different architectures of the interface mechanism by a cycle accurate bit accurate simulation of a SoC integrating a data-flow IP. We show in which configuration the optimal communication scheme can be reached.

Multi-Objective Optimization Design of the Yagi-Uda Antenna with an X-Shape Driven Dipole

A wide-band Yagi-Uda antenna with an x-shape driven dipole for the Meteor Burst Communication (MBC) at the VHF is presented in this paper. The parameter design and multi-objective optimization process of the proposed antenna are given. And effects of the angle that the x-shape driven dipole spread on the performance of the antenna are also studied in detail. The measured and simulated impedance bandwidth of VSWR<1.4 reaches 10%, which doubles the bandwidth of the Yagi-Uda antenna with a dipole driven element. The simulated maximum antenna gain across the operating frequency band, obtained from the optimization process, is about 12.1 dBi. Moreover, good radiation patterns with gain variations less than 1 dBi and the side lobe level less than −15 dBi over the optimized band have also been obtained. Hence the optimized Yagi-Uda antenna with an x-shape driven dipole can effectively widen the operating bandwidth so as to operate as transceiver antenna in MBC.

High-Precision AFC Circuit Applied to 64QAM Point-to-Multipoint Burst Communications

In this paper, we propose a novel open-loop Automatic Frequency Control (AFC) circuit suitable for 64QAM point-to-multipoint (P-MP) burst communications. The proposed AFC contains two frequency offset detectors. One estimates the phase rotation over long intervals to obtain accurate estimates at the cost of phase ambiguity. The other estimates the phase rotation over short intervals and its output is used to resolve the ambiguity in the following phase ambiguity'compensator. Thus, the proposed AFC circuit calculates the phase rotation over sufficiently long periods to yield accurately estimate the carrier frequency offset while suppressing the phase-unwrapping problem. The proposed AFC approaches the Cramer-Rao bound (CRB) and so achieves very small residual frequency offset. The proposed AFC circuit can be implemented with much smaller circuit scale than the conventional devices. Computer simulations and experiments confirm that its residual frequency error is less than of 10 -5 for the frame format considered; this performance is sufficient for the 64QAM - 40 Mbaud system targeted.

Wireless audio and burst communication link with directly modulated THz photoconductive antenna

We demonstrate transmission of audio and burst signals through a prototype THz analog communication link employing laser-gated low-temperature-grown GaAs dipole antenna as THz emitter and receiver. The transmission distance is about 100 cm. By using a direct voltage modulation format, we successfully demodulated a burst signal with a rising time of 41 micros. The corresponding modulating bandwidth achieved was 23 kHz in this first experiment. Noise analysis reveals a 10% power fluctuation in the received signal with on-off extinction ratio of greater than 1000. The transmission of a six-channel analog and burst audio signal with least distortion is also demonstrated. We further demonstrate the fidelity of the transmission of a melody through the THz link with and without any amplification.

A semi-blind joint data and channel estimation based receiver for meteor burst communication

According to the analysis of meteor burst communication (MBC) mechanism, a model of signal processing based on the structure of data frame is suggested for adaptive modulation and coding (AMC) of MBC system in this paper. There are two distinct modes of operation for signal processing: acquisition and tracking. The acquisition mode is a training period to initialize the channel estimation by frame header. The tracking mode is jointly to equalize payload data and to trace channel, where the principle of per-survivor processing (PSP) for maximum likelihood sequence detection (MLSD) is performed. A suboptimal method called D-PSP is adopted to save the computational time and memory size, which agrees with the slow-fading characteristic of meteor channel and makes the MLSD possible for adaptive modulation and coding of MBC system. Computer simulation results are included to support our development.

An Array of Time Varying Kalman Carrier Trackers for Improved Receivers in Burst Communications

In this paper, the problem of carrier synchronization for coded signals in burst communications is addressed. Low SNR, phase jitter, and relatively large initial frequency offset are assumed. A new concept is introduced: synchronization using an array of Kalman trackers, where each tracker is associated with different initial conditions. Based on this concept, an improved joint data detection and carrier synchronization scheme for trellis coded signals is proposed. The proposed scheme uses an array of decision directed Kalman trackers, each initialized with different initial conditions and updated based on tentative decisions from the Viterbi decoder. This scheme reduces drastically the number of cycle slips and hang-ups encountered in the classical PLL and improves significantly the receiver's BER performance. The implementation complexity is relatively low and no special hardware is required.

Threshold extension with Kalman array for synchronization of burst communication

The attainable Frame Error Rate (FER) in satellite burst communication is much too high when a classical Costas Loop is used as the carrier synchronizer. This high FER is due to cycle slips and hang-up of the Costas Loop. We demonstrate the potential to achieve a FER of 3×10-6 using 3 parallel Kalman tracking loops with their initial frequencies spaced apart. We also propose an algorithm for selecting the correct loop for demodulation and use data aided and optimal phase detection for the preamble and payload respectively. This dramatic improvement is at a reasonable complexity.

Novel mobile terminal antenna for meteor burst communication systems

AbstractThe possibility of establishing a communication channel using meteor burst has been known for decades. In recent years there has been a renewed interest on the subject as a way to offer new wireless services at a low cost. This Letter proposes a novel mobile terminal antenna that fits the stringent size requirements demanded while retaining good gain and polarization purity. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 80–83, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10378

A frequency offset estimation technique for frequency-selective fading channels

Rapid frequency offset estimation is required in burst communication systems. The performance of traditional open loop frequency estimation techniques is severely degraded by multipath propagation. We present a new data-aided technique for frequency offset estimation in the presence of strong multipath. The technique allows estimation of the frequency offset with no knowledge of the channel parameters. Results comparing the new technique with the maximum-likelihood estimation technique in a frequency selective Ricean fading environment are presented.

Analysis of data collection system via meteor burst channel

As a way to take maximum advantage of the characteristics of meteor burst communication, the application to data collection networks has been discussed for some time and been reduced to practice. Examples include AMBCS in Alaska and SNOTEL in the Rocky Mountains. Various communication protocols have been proposed for these data collection systems, which have been tested and put into operation. No studies have been carried out on systematically arranging these protocols for analytical comparison. In this paper, the communication protocols are classified. Quantitative analyses have been carried out for the most practical semi-dual individual polling scheme, global polling scheme, and group polling scheme. In the analysis, the average time for collecting the data from all terminals has been derived. All schemes are compared. It is shown that the group polling scheme carrying out polling for each group of terminals is the most efficient if the number of terminals is large. The optimum number of terminals within a group can be derived analytically. © 1998 Scripta Technica, Electron Comm Jpn Pt 1, 82(4): 80–92, 1999

Performance of an adaptive data-rate MBC system using different FEC codings and ARQ protocols

The performance of meteor burst communication using adaptive data-rate modulation is analysed. The transmitted data-rate is a function of the channel state, and is varied in a such way that the probability of bit error is kept constant. Unlike other performance analyses, the message consists of data-packets, thus allowing more realistic ARQ protocols to be analysed. The performance of the system is given in terms of average throughput, probability of successful message completion in a given time span and average waiting time for different message lengths, with or without coding.

Symbol Timing Recovery Algorithms and Their Evaluation for Burst Communication

This paper reviews and presents the simulationresults on the performance of four alternative symboltiming offset estimation algorithms for burst modecommunication. Two basically different approaches are taken to the problem. The first approach isbased on the concept of maximum likelihood estimation,of which two basic varieties are derived and evaluated.These are referred to as the data-driven and the non-data-driven versions. In thedata-driven mode, either the decision symbols from theoutput of the demodulator or a number of known referencesymbols may be used to drive the algorithm. The maximum likelihood algorithms generate an error signalthat can be used in a closed-loop control system toadjust the phase of the sampling clock to the optimumsymbol sampling instant. The second approach uses the basic signal processing technique of tonefiltering using effectively the discrete Fouriertransform. The tone filtering approach results in thedirect estimation of the optimum symbol sampling phase and hence is more of an open-loop approach. Thesimulation results indicate that excellent performanceis achieved with this kind of open-loop approach, evenat low signal to noise ratios and in the presence of some frequency offset as long as the symboltiming offset does not exceed 90% from its optimumpoint. It is also shown that by choosing the propersampling rate, this algorithm results in a simple IIR filtering implementation with one pole that isvery efficient from a processing point ofview.