26 accepted papers
Recently, we proposed weight-constrained nested arrays (WCNA) that have holes in the difference coarray at lags 1 and 2. While this helps in reducing the impact of mutual coupling, the ULA segment in the coarray is ‘one-sided’ from lag L<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink…
Recently, several sparse array constructions have been proposed to reduce the effect of mutual coupling on the direction of arrival (DOA) estimation, by reducing the number of sensor pairs with small separations. For a large number of sensors N and under aperture constraint, $\mathcal{O}\left( {{N^2…
Rational arrays were recently proposed for direction of arrival (DOA) estimation, and some of their advantages were discussed. In this paper we discuss further advantages of rational arrays, by considering their difference coarrays. Although integer arrays such as nested arrays, and coprime arrays a…
Beamspace processing for DOA estimation offers low computational complexity and high DOA resolution. Moreover, unlike classical beamspace methods, convolutional beamspace (CBS) preserves the Vandermonde structure of uniform linear array output, so no additional preparation is needed to apply root-MU…
Ramanujan sums have been shown to have interesting applications in signal processing. Ramanujan subspaces, Ramanujan dictionaries, and Ramanujan filter banks are useful in representing and denoising discrete-time periodic signals. In this paper, we theoretically investigate an ideal interpolation fi…
Coprime arrays are normally used to identify more sources than sensors, using the coarray domain. They can also be used directly in element-space and still have benefits of better accuracy and resolution compared to ULAs. An invariance is buried in each of the two sparse ULAs which constitute a copr…
The recently introduced convolutional beamspace (CBS) method has some advantages over traditional beamspace methods in array processing. This paper introduces a variant which uses IIR instead of FIR filters in the convolutional layer. In CBS, the sources falling in the stopband are assumed to be suf…
Linear arrays used in array processing usually have sensor positions r <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</inf> λ/2 where λ is the wavelength of the impinging signals and r <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="…
Ramanujan filter banks (RFB) have in the past been used to identify periodicities in data. These are analysis filter banks with no synthesis counterpart for perfect reconstruction of the original signal, so they have not been useful for denoising periodic signals. This paper proposes to use a hybrid…
A new method to design the filter for convolutional beamspace (CBS), called Capon-CBS, is proposed. The idea is to design the filter to be a sliding Capon beamformer. Such design takes input statistics into account, so it can do a better job of suppressing the sources that fall in the stopband. Capo…
A new type of beamspace for array processing is introduced called convolutional beamspace. It enjoys the advantages of traditional beamspace such as lower computational complexity, increased parallelism of subband processing, and improved resolution threshold for DOA estimation. But unlike tradition…
In recent years the convergence behavior of random node asynchronous graph communications have been studied for the case of undirected graphs. This paper extends these results to the case of graphs having arbitrary directed edges possibly with a non-diagonalizable adjacency matrix. Assuming that the…
One-bit quantization has attracted attention in massive MIMO, radar, and array processing, due to its simplicity, low cost, and capability of parameter estimation. Specifically, the shape of the covariance of the unquantized data can be estimated from the arcsine law and onebit data, if the unquanti…
In array processing, minimum redundancy arrays (MRA) can identify up to O(N <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) uncorrelated sources (the O(N <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/x…
This paper considers a node-asynchronous implementation of rational ("IIR") filters on graphs, in which the nodes are assumed to wake up randomly and independently from each other, and communicate only with their immediate neighbors. The underlying graph is allowed to be directed, possibly with a no…
Sparse arrays can identify O(N <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) uncorrelated sources using N physical sensors. This property is because the difference coarray, defined as the differences between sensor locations, has uniform lin…
This paper considers an autonomous network in which the nodes communicate only with their neighbors at random time instances, repeatedly and independently. Polynomial graph filters studied in the context of graph signal processing are inadequate to analyze signals on this type of networks. This is d…
If the sampled version x(n)=xc(nT) of a continuous-time signal xc(t) is periodic, it does not necessarily imply that xc(t) is periodic. This paper presents some conditions under which periodicity of xc(t) is indeed implied. The conditions for this implication are more relaxed than bandlimitedness. T…
Ramanujan filter banks (RFB) are useful to generate time-period plane plots which allow one to localize multiple periodic components in the time domain. For such applications, the RFB produces more satisfactory results compared to short time Fourier transforms and other conventional methods, as demo…
Given that a sequence x(n) is periodic with period P belonging to a known integer set {P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> , P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ,…
One-bit quantization has become an important topic in massive MIMO systems, as it offers low cost and low complexity in the implementation. Techniques to achieve high performance in spite of the coarse quantizers have recently been advanced. In the context of array processing and direction-of-arriva…
In order to analyze signals defined over graphs, many concepts from the classical signal processing theory have been extended to the graph case. One of these concepts is the uncertainty principle, which studies the concentration of a signal on a graph and its graph Fourier basis (GFB). An eigenvecto…
Signal processing on graphs finds applications in many areas. Motivated by recent developments, this paper studies the concept of spectrum folding (aliasing) for graph signals under the downsample-then-upsample operation. In this development, we use a special eigenvector structure that is unique to…
In array processing, mutual coupling between sensors has an adverse effect on the estimation of parameters (e.g., DOA). Sparse arrays, such as nested arrays, coprime arrays, and minimum redundancy arrays (MRAs), have reduced mutual coupling compared to uniform linear arrays (ULAs). With N denoting t…
Coprime DFT filter banks (coprime DFTFB) achieve the effect of an MN-DFTFB by using two DFTFBs of size only M and N, where M and N are coprime integers. However, coprime DFTFBs need to be designed properly, to avoid unwanted bumps in stopbands or unsatisfactory total spectrum coverage, quantified by…
We propose a new filter-bank structure for the estimation and tracking of periodicities in time series data. These filter-banks are inspired from recent techniques on period estimation using high-dimensional dictionary representations for periodic signals. Apart from inheriting the numerous advantag…