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A rugged method for distance estimation based on an OFDM signal combined with the Zadoff-Chu sequences is introduced. A software algorithm extracts a coarse distance in time domain exploiting the Zadoff-Chu properties. The distance, then, is fine adjusted evaluating the time offset from the subcarriers phase. Several tests were performed in laboratory considering a very harsh indoor environment and...
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...
This paper proposes a novel algorithm for obtaining an orthogonal frequency division multiplexing (OFDM) signal with a super-imposed synchronization sequence, which is orthogonal to the rest of the signal. It allows to completely eliminate an interference between the super-imposed sequence and the useful signal. The super-imposed sequence does not consume dedicated time and frequency resources and...
This paper analyzes a new dead-reckoning method for pedestrian navigation. In traditional approaches, accelerometers are used to detect steps and to estimate the step length. However, these algorithms must be calibrated for each user and fail in practice when the user moves with an irregular posture like crawling or carrying a victim. In the proposed method the speed is determined from coherence time...
Time varying channel breaks the orthogonality between the subcarriers of Orthogonal Frequency Domain Multiplexing (OFDM). This introduces Intercarrier Interference (ICI). One of the ways to mitigate ICI is to first estimate the channel and then equalize it. In this paper we propose to estimate the channel using Discrete Proplate Spheroidal Sequences (DPS) using pilot carriers interleaved with data...
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,...
Signal-to-noise ratio (SNR) estimation is commonly used in wireless receivers to enhance the performance in different ways. In this paper a novel low complexity SNR estimator for OFDM is proposed. The estimator might be implemented using floating point representation or by using only the sign-bit, and can if desired be effectively implemented by reconfiguring the standard correlator used for time-...
The MIMO system convincingly promises a better bit rate in comparison with a SISO system. The system gets even efficient when OFDM is amalgamated 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,...
We propose a maximum a-posteriori (MAP) based blind algorithm for carrier frequency offset (CFO) and symbol timing offset (STO) estimation, for a convolutionally coded orthogonal frequency division multiplexing (COFDM) system, in an additive white Gaussian noise (AWGN) channel. We derive the MAP estimators mathematically. It is observed that though the MAP metric for CFO estimation gives a good performance...
It is very important to estimate the signal to noise ratio (SNR) of received signal and to transmit the signal effectively for the modern communication system. The performance of existing non-data-aided (NDA) SNR estimation methods are substantially degraded for high level modulation scheme such as M-ary amplitude and phase shift keying (APSK) or quadrature amplitude modulation (QAM). In this paper,...
As an alternative to the OFDM transceiver, single carrier frequency domain equalization (SC FDE) based transceiver has received much attention because of its simple implementation and low peak to average power ratio (PAPR). In this paper, a minimum mean square error (MMSE) FDE for single carrier block transmission is presented to effectively equalize the channels with high frequency selectivity such...
In this paper a processing algorithm that allows for estimating the velocity of multiple reflecting objects with standard OFDM communication signals is discussed. This algorithm does not require any specific coding of the transmit data. The technique can be used in combination with a range estimation algorithm in order to implement active radar sensing functions into a communication system for vehicular...
In this work we present various blind algorithms for estimating signal parameters of unknown OFDM signal waveforms in frequency-selective Rayleigh channels. These algorithms are meant to alleviate some of the challenges facing unauthorized receivers and cognitive radios where many received signal parameters are unknown. Previously known single-symbol algorithms for Maximum Likelihood (ML) Timing and...
In the MIMO-OFDM system channel estimation based on the superimposed pilot is one of most potential and powerful techniques for broad-band wireless communications. In most traditional algorithms, the channel parameters are estimated by calculating the first-order statistical properties of receiving information. However, there are some limitations in such methods. These methods require the first-order...
During the initial uplink synchronization, the BS communicates with MSs to adjust timing and power offsets. The common method to achieve the objective is to use the orthogonal code in the frequency domain for OFDMA systems. Due to the timing offset, the orthogonality of codes is decayed and multiple access interference (MAI) becomes serious. In order to decrease this influence, we proposed the idea...
Traditional OFDM based transmission system uses Cyclic Prefix (CP) in an OFDM symbol in order to maintain orthogonality of transmission. Present days' Ultra-Wideband (UWB) systems use Multi-Band OFDM (MB-OFDM) techniques for transmission in application like Wireless Personal Area Network (WPAN). UWB based systems are power limited by the regulation of FCC. CP introduces correlation in the transmitted...
OFDM can use frequency band efficiently and has strong characteristic for fading channel. But orthogonality collapse when carrier frequency offset and sample timing offset occur. Sample timing offset is represented as phase rotation and ISI. And Carrier frequency offset is represented as phase rotation and ICI. To compensate those effects, many studies were processed based on frequency domain. In...
This paper proposes the practical OFDM channel estimation method with only Kalman filter theory. The method aims to achieve robust OFDM channel estimation from the canonical state space models with (i) a state equation composed of the channel gain and (ii) an observation equation composed of the pilot signal, the channel gain, and the additive noise. The remarkable features of this method are that...
A new compensation method for the frequency shift in the multi-carrier system is studied. The phase offset unbiased estimation and the LMS filter is used to implement the compensation method. Moreover, the compensation method is designed on the FPGA platform and the compensation ability is obtained through the hardware simulation. The simulation results indicate that the UE-LMS compensation method...
In this paper, a Forward Error Coded (FEC) Decision-Directed (FEC-DD) channel estimation scheme is proposed for Multiple-Input Multiple-Output (MIMO) Orthogonal Frequency Division Multiplexing/Space Division Multiple Access (OFDM/SDMA) systems which is based on the Expectation-Conditional Maximization Either (ECME) algorithm. The proposed DD technique is combined with the Optimised Hierarchy Reduced...
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