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For the detect and avoid operation in cognitive radio systems, there is often a requirement to rapidly acquire a pilot carrier in a large frequency uncertainty band. This paper presents a method for rapid pilot carrier acquisition with extremely low computational complexity. A low latency, iterative frequency estimation algorithm is introduced, which accurately determines the pilot carrier frequency...
Detect and avoid (DAA) is a cognitive radio technique for a primary user and secondary users sharing the same spectrum. The DAA spectral sensing system must provide both low decision delay and highly reliable decisions on the presence/absence of primary user transmission. These results provide upper and lower bounds on the decision error rate performance of sensing systems as a function of SNR (signal-to-noise...
In this paper we consider cooperative localization and tracking of primary users (PU) in a cognitive radio network using Bayesian techniques. We use particle filtering methods to track the location of a PU in the network using cooperative localization techniques and present some results for noisy measurements. The cognitive radio (CR) nodes estimate the information related to the geographical position...
This paper considers digital to analog conversion of OFDM signals which have been digitally upconverted to a digital IF (Intermediate Frequency). We examine the effect of clipping and quantization on the received constellations and the uncoded bit error rate (BER) and find that the clipping and quantization can be characterized as a gain and the addition of uncorrelated Gaussian noise. Extensive simulations...
Detect and avoid (DAA) is a simple cognitive radio technique for the coexistence of a primary user and secondary users sharing the same spectrum. Critical to DAA implementation is a detection system which must provide both rapid and accurate decisions on the presence/absence of primary user transmission. In this work, performance results for both energy sensing and waveform sensing are presented in...
Nonlinear system design is a common practice in communication engineering for improved performances in advanced receivers. Here we look into a logarithmic based nonlinear loop for a second order arctan based digital phase locked loop (D-PLL) for frequency synchronisation. The steady state and the acquisition performances of the loop are analyzed. The logarithmic nonlinearity is intentionally introduced...
A highly accurate DFT-based complex exponential parameter estimation algorithm is presented in this paper. It will be shown that for large number of samples and high signal to noise ratio (SNR), the phase estimation error variance performance is only 0.0475 dB above the Cramer-Rao lower bound (CRLB) for phase estimation with unknown frequency and phase. The amplitude estimation error variance performance...
The presence of frequency offsets in the received signal for an orthogonal frequency division multiplexing (OFDM) based multicarrier system leads to inter carrier interferences (ICI). The degradation in the performance of an OFDM system is severe when there is frequency error, which is caused by the loss of orthogonality in the received carrier frequencies. Here, we look into the correction of frequency...
The treatment of phase locked loops (PLL) has been heavily looked into over the past several decades on its performances and analysis, and is a very old topic. However the usage of it has never been reduced with the rapid evolvement of various open loop and closed loop systems. In this paper we analyse the performance of an arctan based digital phase locked loop (DPLL) with a hyperbolic nonlinearity...
Previous Ka band communication experiments have been limited to the observation of geostationary satellites, such as ACTS and OLYMPUS, or have been kept commercial in confidence (Iridium). The Ka band payload on the Australian "FedSat" LEO microsatellite has opened up an opportunity to conduct novel Ka band propagation measurements at varying pointing angles, with the additional challenge...
A statistical analysis of the single-delay multiplication based frequency estimator is treated here. The single-delay multiplication frequency estimator for complex single sinusoid signals is a phase averaged estimator, which is similar to the Kay's estimator. Here we provide a study on the statistical distribution of the frequency estimates made by the estimator, and verify the analytical results...
In this paper, a new technique called the spectral symmetry iterative (SSI) frequency estimation algorithm is disclosed. This algorithm can be used for estimating the frequency and phase of a wide class of signals that are bandpass in nature. This technique can precisely determine the centre frequency of this class of signal in noiseless condition and can yield frequency error variance performance...
A new pilot assisted (PA) carrier frequency offset (CFO) estimation algorithm for OFDM communication system is presented in this paper. This algorithm extends the principle of the discrete Fourier transform (DFT) based single carrier frequency estimation algorithm in S. Reisenfeld and E. Aboutanios (2003). The proposed algorithm comprises of two steps, first a coarse CFO estimator such as the one...
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