Symbol Repetition Research Articles

Novel Waveform Design with a Reduced Cyclic Prefix in MIMO Systems

For well-known orthogonal frequency division multiplexing (OFDM), the cyclic prefix (CP) is essential for coping with multipath channels. Nevertheless, CP is a pure redundant signal, which wastes valuable time–frequency resources. We propose a novel waveform based on symbol repetition, which is presented to cut down the CP overhead in OFDM. In the presented OFDM with symbol repetition (SR-OFDM), one CP is inserted in the front of several transmitted symbols, instead of only one symbol, as in the conventional way. As a result, it can save the overhead created by CP. Furthermore, due to the existence of the remaining CP, the multipath channel can still be converted into the frequency domain, and single-tap equalization can still be used to equalize information free from interference. In addition, we also extend the proposed SR-OFDM into multiple input–multiple output (MIMO) systems. Finally, the proposed schemes are validated by computer simulations under the various channels.

ICI-Robust Transceiver Design for Integration of MIMO-OFDM Radar and MU-MIMO Communication

By virtue of the low cost and flexible deployment, unmanned aerial vehicles (UAVs) are becoming the most promising platform for active radar sensing to find targets in shaded areas and build a temporary communication infrastructure at disaster sites. Radar and wireless communication are essential functions for reliable control of UAVs and real-time exchange of sensed measurements. However, due to the limited payload and power budget of UAVs, it is impossible to mount two individual radar and communication systems, especially on small- or medium-sized UAVs. Recently, joint communication and radar (JCR) systems have emerged as a breakthrough, which perform the communication and radar functions simultaneously on the same hardware platform. Compared to a simple combination of individual communication and radar systems, a UAV JCR system can minimize the implementation cost, power consumption, payload, and radio resource usage. This paper proposes transmit beamformer and receive beamformer designs for a UAV network composed of a UAV JCR base station, a target, and multiple user equipments. Specifically, the UAV transmits an orthogonal frequency division multiplexing (OFDM)-modulated waveform with transmit and receive beamforming to perform multi-input multi-output (MIMO) radar and multiuser-MIMO (MU-MIMO) communication functions simultaneously. Unlike the previous OFDM radar scheme that employs the communication symbol repetition method, a novel receive beamformer design is proposed to resolve the inter-carrier interference problem in the range/velocity estimation process, which therefore does not sacrifice the communication transmission rate. As a result, simulation results show that the proposed scheme achieves a higher radar signal-to-clutter ratio while achieving a higher communication sum-rate than existing schemes.

Reducing cyclic prefix overhead based on symbol repetition in NB-IoT-based maritime communication

With the increasing maritime activities, a great demand of wide-area maritime digital data services is needed. Therefore, Narrowband Internet of Things (NB-IoT) that can provide wide coverage has been expected as an application for maritime communication networks (MCNS). In this paper, we aim to enhance the spectral efficiency in NB-IoT by reducing the cyclic prefix (CP) overhead in random access signal without causing interference. The key point of the proposed scheme is the symbols transmitted for multiple times repeatedly in NB-IoT. Specifically, all CP are removed and multi-path fading effect is eliminated by using a repeated symbol to cover the disturbed symbol to construct a circular convolution structure of the channel with the same effect as adding CP. In addition, a single-tap equalization is still appropriate. To validate the effectiveness of the proposed scheme, simulation results are carried out with respect to the bit error ratio (BER).

Position coding as a means of increasing the range of optical communications links

Subject of study. We present research on the range of atmospheric optical communications links as a function of atmospheric conditions, the types of laser beam modulation used, and the type of interference-resistant coding used. Aim. We develop an approach for increasing the range of free-space optical communications links by improving resistance to atmospheric turbulence. Methods. We show that the modulation technique and channel coding must be compatible if optimum results are to be achieved. Pulse position modulation and interference-resistant position coding are one example of such a compatible combination; a holographic code in which a sequence of pulses representing a 1D linear hologram of a single pulse replaces a single pulse in the desired position is one example of an interference-resistant code. In this case, position modulation is still being used, but in the form of multiple pulse position modulation. A holographic code takes advantage of the fact that holograms are divisible, and a fragment of the hologram can be used for recovery of transmitted data (as well as data hidden by noise). The recovery capacity of the holographic code depends on the hologram length—the number of slots per symbol interval. Main results. We show that holographic coding provides higher interference resistance and a lower probability of detector error and provides the same benefit as an increase in transmitter power. Practical significance. The benefit from holographic coding may be used to either increase the communications range or increase the communications channel reliability. Position coding has the advantages that the redundant information required for interference-resistant encoding is created within the symbol interval, does not affect the symbol repetition frequency, and has no effect on the data transmission rate.

Low CP Overhead Waveform Design for Multi-Path Channels with Timing Synchronization Error

In classical orthogonal frequency division multiplexing (OFDM) systems, inserting the cyclic prefix (CP) is necessary before each symbol to overcome the multi-path effect, which, however, occupies numerous time-frequency radio resources, resulting in hampered spectrum efficiency. To address this issue, in this paper, symbol repetition aware OFDM (SR-OFDM) is developed to lower the overhead of CP. In the proposed SR-OFDM, multiple symbols share the same CP with which we examine that the multi-path channels can also be overcome by a simple single-tap equalization without causing any interference. Moreover, after the discrete Fourier transform at the receiver, different symbols are proved to be separated in the time domain, which is beneficial for lowering the demodulation complexity. Furthermore, it is revealed that the above conclusions still hold even under timing synchronization errors, which makes the proposed SR-OFDM favorable in real systems. Extensive simulations validate the efficacy of our proposed SR-OFDM system under the multi-path channels with or without timing synchronization errors.

A Novel Modulation Technique with Low PAPR for 5G-IoT Systems

For existing orthogonal frequency division multiplexing (OFDM) in 5G internet of things (5G-IoT) systems, one of the critical problems is the high peak to average power ratio (PAPR), which seriously degrades the energy efficiency. To this end, we propose a novel modulation technique with low PAPR for IoT systems, which preserves the advantage of low implementation complexity and ability to fight against multipath channels. The key methodology is the employment of symbol repetition in the frequency domain. Hence, by designing the appropriate phase factors on the repeated symbols, the PAPR of transmitted signals is equivalent to that of an OFDM signal with a reduced size of discrete Fourier transform (DFT). It is demonstrated that, even if there exists repetitive symbols, the proposed method can still maintain an unreduced spectral efficiency performance. Moreover, to evaluate the proposed method, the Monte-Carlo simulations are conducted for the complementary cumulative distribution function (CCDF) and the bit error rate under multipath fading channels. The simulations show that, as CCDF = 10 − 3 , the proposed method can achieve 2.5 dB gains about the PAPR compared with the original OFDM signal.

Iconography Analysis--Symbolism in Joan Miró i Ferrà's Surreal Works

Joan Miró (20 April1839 --25 December 1983), was a Spanish painter, sculptor, ceramicist, printmaker and representative figure of surrealism, is one of the surrealist painting masters in the 20th century who are as famous as Picasso and Dali. In 1924, Miró deeply felt the ideological influence of surrealism in Paris, and he always insisted on the creation of surrealism in his artistic creation career in his later life. In style, Joan Miróis different from Picasso in the same period and Dali in naturalism. Joan Miró said: 'I make no distinction between poetry and painting.'. In his works, it clearly reflects the combination of these two, and ensures the purity, childishness and symbolism of art. This paper starts from the reality, analyzes the poetic grace of the picture caused by the repetition of symbols in Miró's paintings, and focuses on the embodiment of childlike and symbolism in the paintings.

How effective is expressive? Consumer perceptions of new vernacular features in Facebook webcare responses

We investigate how intensifying (e.g. deliberate repetition of punctuation symbols) and non-intensifying (e.g. emoji or chatspeak abbreviations) new vernacular features in responses to consumer complaints on corporate Facebook pages influence perceptions of conversational human voice, interactional justice and corporate credibility, and whether company type and new vernacular usage in the complaint itself moderate these effects. We carried out a 3 (new vernacular features in response: absent, intensifying, non-intensifying) × 2 (new vernacular features in complaint: absent, present) × 2 (company type: progressive, traditional) between-subjects experiment with 718 Flemish consumers. Findings show that organisational responses containing non-intensifying features generate equally positive ratings as those without new vernacular. This points towards an extended norm of appropriate language use in webcare, i.e. adherence to (somewhat informal) Standard Dutch, but with some room for non-intensifying new vernacular. Intensifying expressive compensation strategies, however, negatively impacted conversational human voice, interactional justice and corporate credibility perceptions. The effect on the latter two is mediated to a certain extent by the perceived appropriateness of these features, highlighting the importance of Language Expectancy Theory and Role Theory as underlying frameworks in this field. No clear moderation of company type or new vernacular usage in the consumer complaint was observed.

Digital Textile Design Inspired by Saudi Traditional Symbols of Architecture to Promote the Cultural Identity of Adolescents

Digital Textile Design Inspired by Saudi Traditional Symbols of Architecture to Promote the Cultural Identity of Adolescents

A CP Reduction Scheme Based on Symbol Repetition for Narrow-Band IoT Systems

In this article, we propose a novel waveform with low cyclic prefix (CP) overhead for narrow-band Internet-of-things (NB-IoT) systems. Compared with the classical orthogonal frequency-division multiplexing (OFDM), the proposed waveform employs the concept of symbol repetition on multiple successive OFDM symbols (SR-OFDMs) and only one CP is occupied by multiple SR-OFDM symbols; hence, the CP overhead is reduced significantly, improving the spectral and energy efficiencies in NB-IoT systems. It is proved that the proposed SR-OFDM can effectively fight against the multipath fading channels by a simple single-tap equalization, avoiding the mutual interference among symbols. In addition, it is shown that the proposed SR-OFDM and classical OFDM have the same size of the inverse discrete Fourier transform (IDFT) at the transmitter, which indicates the same subcarrier spacing. Especially, it is demonstrated that the signals of multiple symbols are separated at the receiver, and the demodulation of each symbol can be performed independently, which is helpful to reduce the complexity of symbol demodulation. To evaluate the proposed SR-OFDM, simulations have been done by considering the Stanford university interim (SUI) channels, which have large channel delay spread and exhibit high frequency selectivity.

NTER-SYMBOL IN HO ANH THAI'S NOVELS

Intersymbol is one of the terms related to literary semiotics. At present, the theory of semiotics/cultural semiotics has become popular and is used as a knowledge framework for reference, decoding artistic text. Ho Anh Thai is considered a great writer with dozens of novels. Each of Ho Anh Thai's works has impact and repetition of aesthetic symbols. Ho Anh Thai's novels are rich in generalization, thanks to the system of intersymbols. The voice inside the texts are expressed in the interactions and collisions between legends, archetypes, and symbols. The association of aesthetic symbol series is in the narrative strategy of the writer.

On Single-Error-Detecting Codes for DNA-Based Data Storage

DNA-based storage is considered to be a promising option to accommodate huge amounts of data. The strings of nucleotides are prone to errors though. To reduce the error probability, these strings should satisfy constraints on the ratio of A’s and T’s versus the number of G’s and C’s, and on the maximum number of repeated identical nucleotides. To deal with errors when they occur after all, it is also desirable that the set of DNA-strings possesses certain error correction or detection capabilities. This is established by designing quaternary constrained codes with a specified minimum distance. Here, maximum-sized block codes with a fixed number of G/C symbols, no symbol repetition, and a minimum Hamming distance of two are presented.

Reducing Pilot Overhead: Channel Estimation With Symbol Repetition in MIMO-FBMC Systems

In this article, we aim to reduce the pilot overhead of channel estimation in multiple input multiple output (MIMO) systems employing filter bank multicarrier (FBMC). The key idea is the employment of the concept of symbol repetition in frame structure. Firstly, we propose an MIMO-FBMC system based on block repetition, in which complex-valued symbols are transmitted instead of only real-valued symbols in classic MIMO-FBMC systems without block repetition. Then, we present two low-overhead channel estimation approaches in the block-repetition based MIMO-FBMC system and only two columns of symbols are required as the pilot overhead. However, the existence of the block repetition results in the increased sensitively to the channel coherence time. Then, the two channel estimation approaches are extended into classic MIMO-FBMC systems without block repetition. It is proved that, the proposed methods exhibit significant advantage in terms of pilot overhead, compared with the conventional interference approximation method (IAM) and frequency-division multiplexing (FDM) methods. To evaluate the performances of the proposed approaches, we also derive the Cramer-Rao Bound (CRB) bound, and carry out numerical summations with respects to both mean square error and bit error ratio metrics.

LANGUAGE CHARACTER CHAINS, AS THE BASIS FOR THE FORMATION OF A COGNITIVE MODEL OF VIRTUAL POLITICAL PARTICIPATION

The article states that modern social and political sciences can no longer exist in descriptive mode. New trends are immobilizing outdated tools and concepts. The author proposes a method of defining the properties of a new virtual reality and a tool for interaction with it. The purpose of the study is to analyze the feasibility of a semantic value generator that could help researchers determine the desired characteristics of the target informational impact, repetition, message structure, tools to convey meaning in order to improve the quality of planning and forecasting political influence and forming a stimulating or suppressing influence on political participation and forms. The article presents the hypothesis and methods of creating a mathematical linguistic symbolic model of the field of meaning, located within the global Internet. The author proposes to consider the possibility of predicting the movement of target information flows on the basis of linguistic-social analysis. The basic hypothesis is that politics as a phenomenon is realized by a political action that takes place in the political field and is a consequence of the conscious activity of the individual. Consciousness realizes itself through the formation of thoughts expressed in symbols (words), which presupposes the existence of a field of meaning as a consequence of group interaction of consciousness through the movement of symbolic codes that are produced for the implementation of intraspecific communication. On this basis, the author assumes that such a field can be described in detail, such symbols and versions of their construction in the semantic chains can be counted. The author has carried out a quantitative analysis of the statistics of symbolic usage, as well as the disproportion of individual repetition of symbols of 9 language systems. On the basis of the analysis the hypothesis about the possibility of creating a probabilistic model of the field of meanings of the global virtual Internet network is presented, which will allow to develop mechanisms and methods for predicting the reactions of the global field of meanings and thus increase the quality level of technological information influence on it. The article describes the work created by the author of the Bot program, which, having certain language data, can query the search engine and put the obtained quantitative result in a separate database.

I Know It Was the Blood: Prophetic Initiation and Retributive Justice in the Narratives of John Marrant, Nat Turner, and Frederick Douglass

Abstract This article emphasizes the generative impact of West African religious culture on early African American Christians by analyzing the use of two symbols, wilderness and blood, in the autobiographical accounts of John Marrant, Nat Turner, and Frederick Douglass. I use Theophus Smith's notion of conjure to reconstruct the hermeneutical lens through which early African Americans read and understood the Bible and to explain how the repetition of symbols evinces Africana religious consciousness. While the Bible provided these authors and narrators with a narrative model for storytelling, the structural patterns and thematic emphases repeated in their texts suggest that Africana spirituality, rather than the doctrines of Euro-American Protestantism, primarily informs the processes by which these narrators construct religious meaning. The repetition of the Bible's symbols, tropes, and themes establishes a written tradition of biblical interpretation—a midrash of the Black Church—a hitherto-unacknowledged phenomenon in African diaspora religious history.

A Malaysian Nation Brand: Its Dissemination by Radio Malaya via the Song Tanah Pusaka

A ‘nation branding’ project disseminates the reputation of a country, just as a company’s or product’s brand image is created through advertising and branding. This reputation has a profound impact on a country’s image and the way it is perceived. Increasingly countries are reinventing themselves and, in each time, repackaging its symbolisms for both internal and external audiences. This is essentially a nation branding effort that utilises symbols like colours, the national flower, the national anthem, military uniforms, medallions, rituals and patriotic songs. Radio Malaya, which began broadcasting in 1946, gradually developed into an arm for the propagation public service announcements, news, documentaries, interviews apart from music and songs upon the Federation of Malaya’s independence in 1957. With the establishment of Orkes Radio Malaya in 1961, popular patriotic songs began airing earnestly. This marks the beginning of the government’s intent in branding a national identity and making it identifiable in a sonic manner. This paper discusses the role of the popular patriotic song Tanah Pusaka (1964), in the process of branding the nation through the radio. It focuses on the importance of branding disseminated through the repetition of symbols in songs via the radio. The salient symbols and narrative of collective history embodied in this song are important in maintaining the survival and resilience of the ethnic that share the same collective history. Keywords: Nation branding, branding, popular patriotic songs, radio, symbols.

Orienting and memory to unexpected and/or unfamiliar visual events in children and adults

For children, new experiences occur very often, and learning to differentiate between old and new events is a fundamental process necessary for appropriate reactions to stimuli. Thus the present study is concerned with maturation of brain responses to repeated novel events. We examined the effect of repetition of familiar (meaningful) and unfamiliar (meaningless) symbols on the event-related-potentials (ERPs) recorded during novelty oddball and recognition memory tasks from children, adolescents and young adults. During the novelty oddball task, repetition of the familiar symbols elicited a reduction in the novelty P3 in the ERPs of all age groups, while repetition of the unfamiliar symbols elicited a reduction in novelty P3 amplitude only in children. As expected, recognition memory performance improved with age and was better for familiar than unfamiliar symbols. For all age groups, ERPs to correctly recognized familiar old symbols elicited a larger positivity than ERPs to correctly identified new symbols, indicating a reliable memory effect. However, ERPs to unfamiliar old and new symbols did not differ in adults and adolescents but did differ in children. The data suggest that children process familiar visual symbols in a similar fashion to that of adults, and that children process unfamiliar symbols differently from adults.

Performance analysis on DPSK modulation using symbol repetition and interleaving

SummaryIt is well known that the differential phase shift keying (DPSK) transmission does not require a reference phase and reduces the computational complexity and power consumption of the receiver at the cost of the transmission reliability. To improve the reliability of transmission under such scenario, we use a symbol repetition scheme to the DPSK modulation, such as the IEEE 802.15.6 wireless body area network and the ITU‐T G.9903. However, the message symbol repetition with interleaving in conventional manner as in coherent modulation schemes may degrade the receiver performance because of the noise characteristic of the differential demodulation structure. In this work, we analyze the performance of repeated DPSK system with and without the interleaver and demonstrate which scenario is suitable for each modulation order. We propose a proper transmission setting, which achieves noticeable performance improvement at the receiver as well as enhances the energy efficiency of the communication system. Since it can be implemented with very small modification to existing systems, our results are highly applicable with negligible modification of the hardware structure and thus enable substantially low‐cost implementation in future communication systems including wireless body area network internet of things applications.

Pilgrimage and Audience on the Maharashtrian Vārī

Each year during the monsoon season, devotees of the Hindu Vārkarī sect take to the streets of the cities and towns of Maharashtra, to go on the vārī, a massive annual pilgrimage lasting twenty-one days. The procession of hundreds of thousands of pilgrims is not only seen but heard, as the songs written by the singer-saints of the tradition occupy nearly every moment of the journey. In this article, I examine the relationship between music and pilgrimage procession by focusing on the idea of audience - defined as both the listening public and the act of hearing itself. Rather than limiting pilgrimage to a ritual or symbolic function, I suggest that, as procession, the vārī becomes a context for audition, an open field resists the mere repetition of unchanging ideologies and symbols, and instead creates a broad cultural resonance that can sustain multiple idea simultaneously. Here, I address the idea of resonance by examining the performative nature of the act of procession itself, the repertories and styles of music that accompany the pilgrims from start to finish, and the efficacy of musical sound in shaping the diverse and changing publics that witness the journey.

Effective mirror-mapping-based intercarrier interference cancellation for OFDM underwater acoustic communications

Orthogonal frequency-division multiplexing (OFDM) techniques are promising for underwater acoustic (UWA) communications due to their robustness against large delay spread. However, OFDM systems in UWA channels suffer from intercarrier interference (ICI) caused by the Doppler effect. In this paper, we propose four low-complexity mirror-mapping-based ICI cancellation schemes in OFDM UWA communications without explicitly estimating ICI coefficients or carrier frequency offset (CFO), namely the mirror symbol repetition (MSR) scheme, the mirror conjugate symbol repetition (MCSR) scheme, the mirror conversion transmission (MCVT) scheme, and the mirror conjugate transmission (MCJT) scheme. We theoretically evaluate their performance by deriving their carrier-to-interference power ratio (CIR) expressions in multipath Rayleigh fading channels with CFO. The key idea of our proposed schemes is to employ data repetition within one or two consecutive OFDM symbols according to the mirror-mapping rules and apply the conjugate or conversion operations to remove ICI. Theoretical analyses and numerical results show that the proposed mirror-mapping-based schemes can effectively improve the CIR in comparison with the plain OFDM and the adjacent-mapping-based schemes. In addition, the effects of the channel length and the CFO deviation between two consecutive OFDM symbols are investigated. Finally, to demonstrate their benefits for OFDM UWA communications, these schemes have also been tested in a recent sea experiment conducted in Taiwan in May 2013. The decoding results validate that the proposed mirror-mapping-based schemes significantly improve the bit error rate (BER) performance of OFDM communications in UWA channels.