A Variable Symbol Duration Based FTN Signaling Scheme for PLS

2019 ◽  
Author(s):  
Yuan Li ◽  
Jianquan Wang ◽  
Wanbin Tang ◽  
Xiaoping Li ◽  
Shaoqian Li
Keyword(s):  
Variable Symbol ◽  
Symbol Duration

Non-finite-axiomatizability results in algebraic logic

1992 ◽  
Vol 57 (3) ◽  
pp. 832-843 ◽  
Author(s):  
Balázs Biró
Keyword(s):  
Algebraic Logic ◽  
Relation Algebra ◽  
Equational Theory ◽  
Negative Answer ◽  
Relation Algebras ◽  
Representable Relation Algebra ◽  
Finite Set ◽  
Variable Symbol ◽  
Axiom Systems ◽  
Representable Relation

This paper deals with relation, cylindric and polyadic equality algebras. First of all it addresses a problem of B. Jónsson. He asked whether relation set algebras can be expanded by finitely many new operations in a “reasonable” way so that the class of these expansions would possess a finite equational base. The present paper gives a negative answer to this problem: Our main theorem states that whenever Rs+ is a class that consists of expansions of relation set algebras such that each operation of Rs+ is logical in Jónsson's sense, i.e., is the algebraic counterpart of some (derived) connective of first-order logic, then the equational theory of Rs+ has no finite axiom systems. Similar results are stated for the other classes mentioned above. As a corollary to this theorem we can solve a problem of Tarski and Givant [87], Namely, we claim that the valid formulas of certain languages cannot be axiomatized by a finite set of logical axiom schemes. At the same time we give a negative solution for a version of a problem of Henkin and Monk [74] (cf. also Monk [70] and Németi [89]).Throughout we use the terminology, notation and results of Henkin, Monk, Tarski [71] and [85]. We also use results of Maddux [89a].Notation. RA denotes the class of relation algebras, Rs denotes the class of relation set algebras and RRA is the class of representable relation algebras, i.e. the class of subdirect products of relation set algebras. The symbols RA, Rs and RRA abbreviate also the expressions relation algebra, relation set algebra and representable relation algebra, respectively.For any class C of similar algebras EqC is the set of identities that hold in C, while Eq1C is the set of those identities in EqC that contain at most one variable symbol. (We note that Henkin et al. [85] uses the symbol EqC in another sense.)

Spiking Neuron Model for Temporal Sequence Recognition

2010 ◽  
Vol 22 (1) ◽  
pp. 61-93 ◽  
Author(s):  
Sean Byrnes ◽  
Anthony N. Burkitt ◽  
David B. Grayden ◽  
Hamish Meffin
Keyword(s):  
Excitatory Input ◽  
Biologically Inspired ◽  
Sequence Recognition ◽  
Synaptic Structure ◽  
Correct Sequence ◽  
Spiking Neuron Model ◽  
Multiple Sequences ◽  
Temporal Sequences ◽  
Symbol Duration ◽  
Global Inhibition

A biologically inspired neuronal network that stores and recognizes temporal sequences of symbols is described. Each symbol is represented by excitatory input to distinct groups of neurons (symbol pools). Unambiguous storage of multiple sequences with common subsequences is ensured by partitioning each symbol pool into subpools that respond only when the current symbol has been preceded by a particular sequence of symbols. We describe synaptic structure and neural dynamics that permit the selective activation of subpools by the correct sequence. Symbols may have varying durations of the order of hundreds of milliseconds. Physiologically plausible plasticity mechanisms operate on a time scale of tens of milliseconds; an interaction of the excitatory input with periodic global inhibition bridges this gap so that neural events representing successive symbols occur on this much faster timescale. The network is shown to store multiple overlapping sequences of events. It is robust to variation in symbol duration, it is scalable, and its performance degrades gracefully with perturbation of its parameters.

An Improved Channel Estimation Method in OFDM System

2013 ◽  
Vol 347-350 ◽  
pp. 1646-1652
Author(s):  
Shun Xian Li
Keyword(s):  
Channel Estimation ◽  
Orthogonal Frequency Division Multiplexing ◽  
Fourier Coefficients ◽  
Estimation Method ◽  
Ofdm Systems ◽  
Basis Expansion ◽  
Basis Expansion Model ◽  
Inverse Reconstruction ◽  
Expansion Model ◽  
Symbol Duration

In this paper, we will focus on channel estimation (CE) in orthogonal frequency-division multiplexing (OFDM) systems. The time-varying (TV) channelsare modeled by a basis expansion model (BEM). Due to the time-variation, the channel matrix in the frequency domain is no longer diagonal, but approximately banded.We use a pilot-aided algorithm for estimation of rapidly varying wireless channels in OFDM systems. Theperforms is goodwhen the channels vary on the scale of a single OFDM symbol duration, which occurs in mobile communication scenarios such as WiMAX, WAVE, and DVB-T.We recover Fourier coefficients of the channel taps by the pilot information.We then estimate the BEM coefficients of the channel taps from their respective Fourier coefficients using a recently developed inverse reconstruction method.We compare some BEM models in inverse methodsto find out the best ones in certain conditions.

A Novel Spatial Modulation Scheme for MIMO System

2012 ◽  
Vol 198-199 ◽  
pp. 1573-1577 ◽  
Author(s):  
Yao Yuan Zhang ◽  
Zi Sheng Zhang ◽  
Ya Fei Lian ◽  
Qian Ding
Keyword(s):  
Rayleigh Fading ◽  
Mimo System ◽  
Spectrum Efficiency ◽  
Spatial Modulation ◽  
Modulation Scheme ◽  
Channel Correlation ◽  
Optimal Detector ◽  
Shift Keying ◽  
Correlated Channel ◽  
Symbol Duration

A novel spatial modulation scheme based on Space-Shift Keying (SSK) modulation is introduced for MIMO system. The proposed scheme doubles the spectrum efficiency of SSK by assigning unique symbols to different combinations of antenna indexes per symbol duration, while retaining the SSK’s inherent advantages. The optimal detector is utilized at the receiver simultaneously. Analytical and simulation results show: 1) in Rayleigh fading channel scenario，the obtained gains in SNR for the same spectral efficiency of the proposed scheme over amplitude/phase modulation (APM), vertical Bell Labs layered structure (V-BLAST) and spatial modulation (SM) systems are obvious; 2) under the correlated channel assumption, the new one still outperforms SM and V-BLAST clearly, which indicates the new one is more robust in the presence of channel correlation.

scholarly journals Inner-symbol Interference (INSI) reduction in OFDM system using distinctive characteristics of the pilot symbols

2020 ◽  
Vol 27 (1) ◽  
pp. 122-129
Author(s):  
Mohammad Bakkar
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Estimation Method ◽  
Multipath Fading ◽  
Estimation Accuracy ◽  
Ofdm Symbol ◽  
Pilot Signal ◽  
Ofdm Signal ◽  
The Times ◽  
Symbol Duration ◽  
Inter Symbol Interference

This research presents a wireless communication system using Quadrature Amplitude Modulation (16QAM) depending on using of the Orthogonal Frequency Division Multiplexing (OFDM).  OFDM transmission system can effectively reduce inter symbol interference (ISI) caused by multipath fading, especially in the case of broadband data transmission. There are two kind of interference; inter symbol interference (ITSI) and inner symbol interference (INSI). ITSI is the interference caused by the delayed waves with larger than OFDM symbol duration, in order to avoid ITSI effectively, we insert guard interval every each OFDM symbol. On other hands, INSI is the interference caused by the delayed waves with less than OFDM symbol duration. To avoid INSI, this work proposes a new scheme in order to estimate the times of delayed waves by using distinctive characteristics of OFDM signal, which is inserted pilot signal periodically in frequency axis before IFFT at the transmitter. In this paper, we evaluate the estimation accuracy of the proposed estimation method and the BER performance of the proposed system under multipath fading environment by computer simulation with MATLAB.

scholarly journals Improvement of the Communication between RFID Sensor Network Devices Used to Control and Monitor a Building

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Abdelhamid Bou-El-Harmel ◽  
Ali Benbassou ◽  
Jamal Belkadid
Keyword(s):  
Sensor Network ◽  
Economic Loss ◽  
Dipole Antenna ◽  
Security Threats ◽  
Transmission Power ◽  
Propagation Channel ◽  
Channel Characteristics ◽  
Transmission Parameters ◽  
Communication Problems ◽  
Symbol Duration

In the RFID sensor network (RSN), the devices communicate with each other by RF waves using the antennas through a propagation channel. A poor communication between these devices results in either a significant economic loss or security threats. The communication problems can have several origins depending on the type of antenna used and the nature of the propagation channel. In this work, our objective is to limit the communication problems between the nodes of this network that are linked to the characteristics of an indoor propagation channel. The goal is to predict the channel characteristics using the 3D ray tracing method in order to select the appropriate transmission parameters such as transmission power and duration of a symbol. To achieve this, we have modeled a building that is sectioned as a propagation channel where network devices are deployed for control and monitoring. The communication was made at 915 MHz using the quasi-isotropic 3D cubic antenna that we designed as well as a conventional dipole antenna in order to compare the results. We have found that the use of the 3D cubic antenna gives several advantages to the RFID sensor network compared to the most commonly used conventional dipole antenna, such as a transmission power of 0 dBm which automatically leads to an increase in the lifetime of the devices, as well as a minimum symbol duration of around 219.78 ns which gives a high bit rate.

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