Symbol Structure Research Articles

Designing and Implementation of 2D Character Barcode

Base on 2D barcode DM and QR, a new2D character barcode, is proposed in this paper. It is different with the traditional 2D barcode. It is a character matrix instead of the image barcode. The encoding rules, decoding rules and symbol structure of this character barcode are designed and implemented. Then the error-correcting code is studied and added into the encoded information. Finally the 2D character barcode is verified on PC. The experiments show that the 2D character barcode has very small capacity and can be transmitted as the character message among the mobile terminals. It can well overcome high loss rate when the image of 2D barcode is transmitted as a multimedia message and avoid the problem that some mobile terminals can not support the multimedia messages.

A New Modified MPPM for High-Speed Wireless Optical Communication Systems

Previous work proposed combining multipulse pulse position modulation (MPPM) with pulse amplitude modulation to form multipulse amplitude and position modulation (MPAPM), which is a hybrid modulation that results in an improvement in bandwidth efficiency but a degradation in power efficiency. In this paper, to achieve greater power efficiency and a better data rate, we propose multipulse dual amplitude-width modulation, based on MPAPM and pulse width modulation. The proposed scheme shows a remarkable improvement in data rate and a 1.5-dB improvement in power efficiency over MPAPM, while sustaining the bandwidth efficiency. After introducing symbol structure, we present the theoretical expressions of spectral efficiency, the power requirements, and the normalized data rate, as well as the results of comparing the proposed modulation to MPPM and MPAPM.

Political Symbolism and the Fall of the USSR

When Gorbachev came to power he inherited not simply a system in crisis, but a structure of symbols that was embedded within the broader political system and which was also in crisis. Given the ideocratic nature of the Soviet system, any change to that system would require symbolic change as well. This essay charts how Gorbachev sought to come to grips with this problem, investing some symbols with new meaning while rejecting others. It shows how ultimately he was unable to produce a new, coherent narrative.

POETRY BY RAINIS IN LATGALIAN

POETRY BY RAINIS IN LATGALIAN

Signal-to-Noise Ratio Estimation Algorithm for Advanced DVB-RCS Systems

This paper presents a signal-to-noise ratio (SNR) estimation algorithm for advanced Digital Video Broadcasting-Return Channel via Satellite (DVB-RCS) systems using adaptive coding and modulation (ACM) in the reverse link of broadband satellite systems. Due to the absence of a repetitive pilot symbol structure, SNR estimation has to be performed using the fixed symbol preamble data. Moreover, sporadic nature of data traffic on the return link causes variation in interference level from slot to slot and, therefore, the estimation has to be done within one traffic slot duration. Hence, it becomes necessary to use a combination of data-aided (DA) and decision-directed (DD) algorithms so as to make use of traffic data. A non-data-aided (NDA) estimator that was previously proposed by the authors for binary phase shift keying (BPSK) and QPSK schemes is extended to 8-PSK in a decision directed manner. This estimator shows improved performance over existing estimators. The inherent bias of DD approach at low values of SNR is reduced by using a hybrid approach, i.e., using the proposed estimator at moderate/high values of SNR and the moments-based estimator ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> ) at low values of SNR. Overall improved performance of the proposed hybrid estimator, in terms of accuracy and complexity, makes it an attractive choice for implementing ACM in advanced DVB-RCS systems.

Symbol w filozofii religii Paula Tillicha

The concept of a symbol has its meaning not only in epistemology and psychology but also in philosophy of religion. The reconstructed concept of a religious symbol, based on Paul Tillich’s understanding and compared with present achievements in the field, is current and interesting motive to investigate the phenomenon of religion. Tillich’s existential interpretation of the ontology-based symbol, makes it more understandable and open for contemporary man and world questions concerning religion. The structure of religious symbol, its use and interpretation make man – religion communication more comprehensive and clear.

Simple Wide Range Carrier Frequency Offset Estimator for Coherent Optical OFDM

Coherent optical orthogonal frequency division multiplexing systems have a wide carrier frequency offset (CFO) range due to the frequency inaccuracy of lasers. In this letter, a simple wide range CFO estimator is proposed. In the proposed algorithm, wide estimation range and high accuracy are achieved by using a combination of the Chinese remainder theorem (CRT) for the integer part of CFO and fine estimation for the fractional part of CFO. For the proposed estimator, a training symbol structure consisting of two identical symbols is also suggested. The sizes of subsymbols of the training symbols are relatively prime to apply CRT. Simulations verify the validity of the proposed algorithm. The results indicate that the range of estimator is as large as the sampling frequency.

Frequency domain multi‐user receivers for IEEE 802.15.4a short‐range communication network

ABSTRACTIn this letter, we propose frequency domain receivers for an IEEE 802.15.4a short‐range communication network: the uplink case is taken into account, considering a scenario where several devices communicate with a coordinator node. The channel model has been also derived according to the IEEE 802.15.4a recommendations. Results show that the proposed approach can be beneficial in short‐range systems under severe conditions of multipath propagation and interference. An interesting novelty of the proposed approach is that both single‐user and multi‐user FD receivers based on the minimum mean square error criterion can be derived by exploiting the zero padding technique which is intrinsic in the symbol structure of the standard. Copyright © 2012 John Wiley &amp; Sons, Ltd.

Signal-to-noise ratio estimation algorithm for adaptive coding and modulation in advanced digital video broadcasting–radar cross section satellite systems

This paper presents a signal-to-noise ratio (SNR) estimation algorithm for advanced digital video broadcasting- return channel via satellite (DVB-RCS) systems using adaptive coding and modulation (ACM). Due to the absence of a repetitive pilot symbol structure, SNR estimation has to be performed using the fixed symbol preamble data. Moreover, sporadic nature of data traffic on the return link causes variation in interference level from slot to slot and, therefore, the estimation has to be done within one traffic slot duration. Hence, it becomes necessary to use a combination of data-aided and decision-directed (DD) algorithms so as to make use of traffic data. A non-data-aided estimator that was previously proposed by the authors for binary and quadrature phase shift keying schemes is extended to 8-PSK in a decision directed manner. The inherent bias of DD approach at low values of SNR is reduced by using a hybrid approach, that is, using the proposed estimator at moderate/high values of SNR and the moments-based estimator (M2M4) at low values of SNR. Overall improved performance of the proposed hybrid estimator, in terms of accuracy and complexity, makes it an attractive choice for implementing ACM in advanced DVB-RCS systems.

The structure and evolution of symbol

The received opinion is that symbol is an evolutionary prerequisite for syntax. This paper shows two things: 1) symbol is not a monolithic phenomenon, and 2) symbol and syntax must have co-evolved. I argue that full-blown syntax requires only three building blocks: signs, concatenation, grammar (constraints on concatenation). Functional dependencies between the blocks suggest the four-stage model of syntactic evolution, compatible with several earlier scenarios: (1) signs, (2) increased number of signs, (3) commutative concatenation of signs, (4) grammatical (noncommutative) concatenation of signs. The main claim of the paper is that symbolic reference comprises up to five distinct interpretative correlates: mental imagery, denotation, paradigmatic connotation, syntagmatic connotation, and definition. I show that the correlates form an evolutionary sequence, some stages of which can be aligned with certain stages of syntactic evolution.

Dual Amplitude-Width PPM for Free Space Optical Systems

The PPM (Pulse Position Modulation) is commonly used in Free Space Optic (FSO) systems owing to its power efficiency, but it shows a rapid decline in spectral efficiency with increase in the power efficiency and moderate data rate. In order to improve these two parameters, we present a modified modulation scheme of the existing PPM, on the basis of PPM, PAM (Pulse Amplitude Modulation) and PWM (Pulse Width Modulation). This modified version called DAWPPM (Dual Amplitude-Width PPM). The average power requirements, bandwidth efficiency and normalized data rate are studied after introducing symbol structure. The proposed scheme shows an improvement in terms of data rate and bandwidth efficiency, and when in come to power efficiency it shows lower efficiency compared to PPM. We present theoretical expressions of data rate, spectral efficiency, and normalized power requirements, and we present comparison results to PPM modulation scheme. Index Terms—PPM, PAM, PWM, DAWPPM, data rate, power requirements and bandwidth efficiency.

Blind Channel Estimation for Amplify-and-Forward Two-Way Relay Networks Employing $M$-PSK Modulation

We consider the problem of channel estimation for amplify-and-forward (AF) two-way relay networks (TWRNs). Most works on this problem focus on pilot-based approaches which impose a significant training overhead that reduces the spectral efficiency of the system. To avoid such losses, this work proposes blind channel estimation algorithms for AF TWRNs that employ constant-modulus (CM) signaling. Our main algorithm is based on the deterministic maximum likelihood (DML) approach. Assuming M-PSK modulation, we show that the resulting estimator is consistent and approaches the true channel with high probability at high SNR for modulation orders higher than 2. For BPSK, however, the DML performs poorly and we propose an alternative algorithm that performs much better by taking into account the BPSK structure of the data symbols. For comparative purposes, we also investigate the Gaussian maximum-likelihood (GML) approach which treats the data symbols as Gaussian-distributed nuisance parameters. We derive the Cramer-Rao bound and use Monte-Carlo simulations to investigate the mean squared error (MSE) performance of the proposed algorithms. We also compare the symbol-error rate (SER) performance of the DML algorithm with that of the training-based least-squares (LS) algorithm and demonstrate that the DML offers a superior tradeoff between accuracy and spectral efficiency.

Maximum Likelihood Estimation of Time and Carrier Frequency Offset for DVB-T2

The new terrestrial digital video broadcasting standard DVB-T2 provides a specific symbol - called P1-symbol - for the initial time and frequency synchronization. In this paper the maximum likelihood (ML) time and carrier frequency offset (CFO) synchronization scheme, which exploits the structure of the P1 symbol in both time and frequency domains is derived. Two lower-complexity solutions are then proposed: (1) a ML estimator that only exploits the time structure of the P1 symbol and (2) a pseudo ML (PML) scheme that resorts to a suboptimal CFO estimator while still performing ML time synchronization. The proposed schemes are compared in terms of both synchronization capabilities and implementation complexity. The Cramèr-Rao bounds for the CFO estimators are also evaluated. Simulation results in a typical DVB-T2 scenario show that both ML and PML schemes have a very close performance while significantly outperforming existing schemes.

Design and Implementation of an Omni-Directional Underwater Acoustic Micro-Modem Based on a Low-Power Micro-Controller Unit

For decades, underwater acoustic communication has been restricted to the point-to-point long distance applications such as deep sea probes and offshore oil fields. For this reason, previous acoustic modems were typically characterized by high data rates and long working ranges at the expense of large size and high power consumption. Recently, as the need for underwater wireless sensor networks (UWSNs) has increased, the research and development of compact and low-power consuming communication devices has become the focus. From the consideration that the requisites of acoustic modems for UWSNs are low power consumption, omni-directional beam pattern, low cost and so on, in this paper, we design and implement an omni-directional underwater acoustic micro-modem satisfying these requirements. In order to execute fast digital domain signal processing and support flexible interfaces with other peripherals, an ARM Cortex-M3 is embedded in the micro-modem. Also, for the realization of small and omni-directional properties, a spherical transducer having a resonant frequency of 70 kHz and a diameter of 34 mm is utilized for the implementation. Physical layer frame format and symbol structure for efficient packet-based underwater communication systems are also investigated. The developed acoustic micro-modem is verified analytically and experimentally in indoor and outdoor environments in terms of functionality and performance. Since the modem satisfies the requirements for use in UWSNs, it could be deployed in a wide range of applications requiring underwater acoustic communication.

Design of the Recognition and Decoding System of PDF417 Barcode Based on LabVIEW

The symbol structure of PDF417 barcode was introduced in detail, and a recognition and decoding system of PDF417 barcode based on software development platform of the LabVIEW virtual instrument was designed and implemented. The system can process and analyze the images containing PDF417 barcode collected by camera in real time, achieve the fast and omnibearing decoding of the barcode.

Enhanced PHY symbol structure based on the IEEE 802.15.4a standardization and orthogonal pulses for 3D positioning

According to IEEE 802.15.4a standardization, an ultra wideband PHY symbol is capable of carrying two bits of information and only one pulse shall be transmitted in each symbol. To prevent inter symbol interference caused by multipath effect, the guard interval is present between the possible burst positions. In order to make full use of the symbol for estimating the azimuth and the elevation of target, we can add additional information at the guard interval position, if the pulse used at the possible burst position is different from the pulse used at the guard interval position. Using the orthonormality between the multiple pulses, furthermore, inter symbol interference can be avoided at the correlation receiver. In this paper, as the first step for estimating the azimuth and the elevation information, we propose a novel PHY symbol structure for IR-UWB system based on IEEE 802.15.4a standardization and orthogonal pulses to enhance the data rates without the bit-error-rate (BER) performance degradation. In the proposed scheme, the pulse used at the possible burst position is the modified hermite polynomial (MHP) pulse of order n equal to 3 and the pulse used at guard interval position is the MHP pulse of order n equal to 4. The performance of the proposed structure is evaluated by computer simulations over the IEEE 802.15.4a channel model. Simulation results show that the proposed symbol structure with orthogonal pulses can double the data rates of the systems without BER performance degradation.

Mechanical Product Analogy Design Method Based on Structure Similarity

By use of function-behavior-structure-shape model, an analogy design method for mechanical products based on structure similarity is presented. Structure model includes qualitative models of symbol part structure and product assembly structure. It is an information carrier to connect conceptual design and detail design. The main aim to set up structure model is to realize design reuse. By use of the structure similarity between source design and target design the product design is picked-up. The 16 types of design processes based on analogy are present. Finally structure design modeling is divided into three levels, namely symbol modeling, structure modeling and feature modeling. The structure hierarchical modeling method is discussed.

Quinian bootstrapping or Fodorian combination? Core and constructed knowledge of number

AbstractAccording to Carey (2009), humans construct new concepts by abstracting structural relations among sets of partly unspecified symbols, and then analogically mapping those symbol structures onto the target domain. Using the development of integer concepts as an example, I give reasons to doubt this account and to consider other ways in which language and symbol learning foster conceptual development.

Joyce, Coleridge, and the Eastern Aesthetic

This essay traces Joyce's use of eastern imagery in Ulysses back to the poetics of Samuel Taylor Coleridge, ultimately offering an alternative to Edward Said's familiar argument for Orientalism as a mode of western domination. Though the relationship between Coleridge and Joyce has been left largely unexplored, Joyce's allusions to Coleridge's "Kubla Khan" and The Rime of the Ancient Mariner at crucial points in the novel reveal the importance of The Arabian Nights as a narrative model as well as a sourcebook for aesthetic misrepresentations of the East. Sharing a common interest in the theme of loss and recovery in both its literal and figurative forms, Coleridge and Joyce deploy eastern imagery as a way of eliciting a multivalent structure of symbol and allusion whereby the representation of the particular aspires to the universal.

A framework for applying the concept of significant properties to datasets

The concept of significant properties, properties that must be identified and preserved in any successful digital object preservation, is now common in data curation. Although this notion has clearly demonstrated its usefulness in cultural heritage domains its application to the preservation of scientific datasets is not as well developed. One obstacle to this application is that the familiar preservation models are not sufficiently explicit to identify the relevant entities, properties, and relationships involved in dataset preservation. We present a logic-based formal framework of dataset concepts that provides the levels of abstraction necessary to identify and correctly assign significant properties to their appropriate entities. A unique feature of this model is that it recognizes that a typed symbol structure is a unique requirement for datasets, but not for other information objects.