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Considering increasing number of hybrid and electric vehicles, a growing number of car-pedestrian accident become a problem because these vehicles are virtually silent at low speeds where tire noise is not significant. To cope with this problem, a real-time approaching vehicle detection technique for pedestrians using acoustic digital communication is proposed. In this technique, a vehicle transmits...
A novel method for distance estimation is introduced, based on an OFDM signal combined with the Zadoff-Chu Sequences. By exploiting the properties of these sequences it is possible to evaluate the distance between a transmitter and a receiver with a very good precision and accuracy. The technique effectiveness is demonstrated in a real operating environment by measuring the distance between two active...
In this paper we develop a new spectrum sharing scheme that uses compressive sensing to support the coexistence of the sporadic machine-to-machine (M2M) communications and the persistent conventional communications such as the 5G cellular transmissions within the same channel. The redundancy in the transmitted signals, such as training symbols, pilots, MAC overheads and correlated data, is exploited...
In this paper, the problem of resource allocation for OFDM user to guarantee secure communication is considered. There exists an active eavesdropper which is able to either eavesdrop or jam the ongoing information transmission of OFDM user but not both at the same time. The OFDM user aim is to minimize its transmit power over all subcarriers while maintaining its secrecy rate above a predefined threshold...
According to the cost and power consumption of wireless communication receiver under high-precision quantization, this paper discusses the effect on the performance of channel estimation for OFDM systems with low-precision quantization. Theoretical analysis and simulation results show that the low-precision quantization degrades the system performance. However, the optimized channel estimation algorithm...
The present paper describes an Ultra-Wideband (UWB) communication system based on the Orthogonal Frequency Division Multiplexing (OFDM) modulation scheme. The system uses a small number of sub-carrier frequencies which allow the straightforward implementation of the OFDM modulator and demodulator without the use of Discrete Fourier Transform (DFT). An experimental RF transceiver based upon the proposed...
This paper describes the evolution of powerline communications for the control of power distribution grids. First generation ripple control systems provide one-way communication, with which centralized load control and peak shaving have been performed for many years. The European standards body CENELEC restricted the use of frequencies between 3 kHz and 95 kHz for two-way communications for electricity...
OFDM is an important technology for 4G and being used of the wireless data communication, but it is very difficult to have a blind recognition method about subcarrier modulation type of OFDM. The characteristics of cyclostationarity modulation spectrum which will be not affected by noise, This paper gives out a blind recognition method about modulation types of OFDM subcarrier based on coefficient...
In this paper, a new trend of Space Time Block codes-Orthogonal Frequency Division Multiplexing (STBC-OFDM) with Convolutional and Turbo codes. The applied method is based on Alamouti's scheme. We examine the performance of two, three and four transmitters with one receiver over Nakagami-m fading channel using convolutional and turbo codes using different types of modulation such as BPSK and 64-QAM...
In this study, we analyze the role of interleavers in OFDMA system for ensuring uniform BER performance amongst the active users and also investigate their respective PAPR properties. At first considering a generic system in a slowly changing multipath channel where high dispersion in the individual users performance exists, we apply different types of interleaving and show that they in general help...
This contribution presents low computational complexity versions of orthogonal frequency division multiplexing (OFDM) modulation scheme for the implementation of clustered-OFDM systems for data transmission in the passband frequency. Among the proposed schemes, which are named Hermitian symmetric OFDM (HS-OFDM) I and HS-OFDM II, the HS-OFDM II can offer computational complexity reduction in comparison...
Impulse noise (IN) is one of the major impairments for data transmission over power lines. For power line communications (PLC) systems with bandwidths in the high kHz to MHz range, IN occurs in bursts. As long as those bursts are sufficiently short compared to a signal-processing (e.g. coding) frame, there is hope to successfully mitigate IN. In this paper, we introduce a new IN mitigation technique...
The MIMO system convincingly promises a better bit rate in comparison with a SISO system. The system gets even efficient when OFDM is implemented with MIMO to obtain better data rates even in hostile channel environment. Research establishes OFDM as a potential candidate for use in MIMO systems for the reasons like inherent FFT, waveform adaptation, advanced antenna techniques, multiple access, interoperability,...
The effect of a power amplifier nonlinearity on multi-antenna orthogonal frequency division multiplexing (OFDM) transmitters utilizing subcarrier beamforming is investigated. Theoretical analysis and simulation shows that such systems can exhibit significant performance degradation due to the power amplifier nonlinearity when there are channel state feedback errors. The SINR degradation under solely...
We consider the problem of multicasting from a single source to a set of destinations. We assume that the source can either reach the destinations directly or forward its traffic through a set of relays. Due to the non-linear attenuation of the signal with distance, employing the relays can help to improve the signal quality at the destinations. Meanwhile, relays also consume energy for retransmission...
Spectrally Efficient Frequency Division Multiplexing (SEFDM) systems aim to reduce the utilized spectrum by multiplexing non-orthogonal overlapped carriers. Since the per carrier transmission rate is maintained, SEFDM yields higher spectral efficiency relative to an equivalent Orthogonal Frequency Division Multiplexing (OFDM) system. Yet, due to the loss of the orthogonality, detection of the SEFDM...
This article addresses the signal distortion caused by receiver phase noise (PN) on OFDM waveforms in direct-conversion radio receivers. A closed-form solution for the observed signal-to-interference-plus-noise ratio (SINR) is derived, describing the level of intercarrier interference (ICI) stemming from PN. Compared to existing literature, the analysis is valid for arbitrary oscillator spectral shape,...
Kolmogorov-Smirnov (K-S) test-a non-parametric method to measure the goodness of fit, is applied for automatic modulation classification (AMC) in this paper. The basic procedure involves computing the empirical cumulative distribution function (ECDF) of some decision statistic derived from the received signal, and comparing it with the CDFs of the signal under each candidate modulation format. The...
Cognitive radio (CR) technology provides great flexibility in spectrum utilization with orthogonal frequency-division multiplexing (OFDM) as its candidate transmission technique. In this paper, we propose a simple spectrum shaping scheme for OFDM-based CRs to enhance spectral compactness and ensure bandwidth efficiency. By mapping antipodal symbol pairs onto adjacent subcarriers at the edges of the...
In this paper, we discuss the challenges associated with integrating multiuser OFDMA in a single cell IEEE 802.11 based wireless ad hoc network and propose a new, dynamic and robust approach to improve it. Our new MAC, using OFDMA in the physical layer, can incorporate multiple concurrent transmissions or receptions in a dynamic manner and can adjust the collision probability based on the traffic...
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