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Articles 1 - 16 of 16
Full-Text Articles in Engineering
Performance Analysis Of The Dominant Mode Rejection Beamformer, Enlong Hu
Performance Analysis Of The Dominant Mode Rejection Beamformer, Enlong Hu
Dissertations
In array signal processing over challenging environments, due to the non-stationarity nature of data, it is difficult to obtain enough number of data snapshots to construct an adaptive beamformer (ABF) for detecting weak signal embedded in strong interferences. One type of adaptive method targeting for such applications is the dominant mode rejection (DMR) method, which uses a reshaped eigen-decomposition of sample covariance matrix (SCM) to define a subspace containing the dominant interferers to be rejected, thereby allowing it to detect weak signal in the presence of strong interferences. The DMR weight vector takes a form similar to the adaptive minimum …
Statistical Performance Analysis Of Sparse Linear Arrays, Mianzhi Wang
Statistical Performance Analysis Of Sparse Linear Arrays, Mianzhi Wang
McKelvey School of Engineering Theses & Dissertations
Direction-of-arrival (DOA) estimation remains an important topic in array signal processing. With uniform linear arrays (ULAs), traditional subspace-based methods can resolve only up to M-1 sources using M sensors. On the other hand, by exploiting their so-called difference coarray model, sparse linear arrays, such as co-prime and nested arrays, can resolve up to O(M^2) sources using only O(M) sensors. Various new sparse linear array geometries were proposed and many direction-finding algorithms were developed based on sparse linear arrays. However, the statistical performance of such arrays has not been analytically conducted. In this dissertation, we (i) study the asymptotic performance of …
Non-Orthogonal Multiple Access Based On Hybrid Beamforming For Mmwave Systems, Mojtaba Ahmadi Almasi, Hani Mehrpouyan
Non-Orthogonal Multiple Access Based On Hybrid Beamforming For Mmwave Systems, Mojtaba Ahmadi Almasi, Hani Mehrpouyan
Electrical and Computer Engineering Faculty Publications and Presentations
This paper aims to study the utilization of non-orthogonal multiple access (NOMA) in hybrid beamforming (HB) multiuser systems, called HB-NOMA, to serve a large number of mobile users. First, a sum-rate expression for the HB-NOMA problem is formulated. Second, an effective algorithm is proposed to maximize the sum-rate. Then, a lower bound is derived under two cases: i) the angle between the effective channel vectors of the MU with the highest channel gain and other MUs located inside a cluster is zero (or close to it) which is denoted by perfect correlation, and ii) this angle is non-zero, which we …
On Fixed Beamforming In Sectored Mmwave Ultra Dense Networks At 73ghz, Jasmina Mcmenamy, Haris Kremo, George A. Ropokis, Adam Narbudowicz
On Fixed Beamforming In Sectored Mmwave Ultra Dense Networks At 73ghz, Jasmina Mcmenamy, Haris Kremo, George A. Ropokis, Adam Narbudowicz
Conference papers
We investigate the use of fixed analogue transmit beamforming for downlink communication in millimetre-wave (mmWave) band ultra-dense networks (UDNs) at 73GHz. Our simulation study is based on 3D radiation patterns using a real design of large planar antenna arrays with different horizontal beamwidths and full characterisation of interference. The effects of network densification are captured through different ratios of the number of access points (APs) to the number of users. We quantify the system's performance by evaluating outage and achievable rate. The results show that users with rates around the mean benefit more from the densification than from narrowing the …
Power Control And Beamforming Design For Swipt In Af Two-Way Relay Networks, Wei Wang, Rui Wang, Hani Mehrpouyan, Guoan Zhang
Power Control And Beamforming Design For Swipt In Af Two-Way Relay Networks, Wei Wang, Rui Wang, Hani Mehrpouyan, Guoan Zhang
Electrical and Computer Engineering Faculty Publications and Presentations
In this paper, we study the problem of joint power control and beamforming design for simultaneous wireless information and power transfer (SWIPT) in an amplify-and-forward (AF) based two-way relaying (TWR) network. The considered system model consists of two source nodes and a relay node. Two single-antenna source nodes receive information and energy simultaneously via power splitting (PS) from the signals sent by a multi-antenna relay node. Our objective is to maximize the weighted sum power at the two source nodes subject to quality of service (QoS) constraints and the transmit power constraints. However, the joint optimization of the relay beamforming …
Improved Channel Probing For Secret Key Generation With Multiple Antenna Systems, Britton T. Quist
Improved Channel Probing For Secret Key Generation With Multiple Antenna Systems, Britton T. Quist
Theses and Dissertations
Establishing secret keys from the commonly-observed randomness of reciprocal wireless propagation channels has recently received considerable attention. In this work we propose improved strategies for channel estimation between MIMO or beamforming systems for secret key generation. The amount of mutual information that can be extracted from the channel matrix estimates is determined by the quality of channel matrix estimates. By allocating increased energy to channel estimation for higher gain beamforming combinations at the expense of low-gain combinations, key establishment performance can be increased. Formalizing the notion of preferential energy allocation to the most efficient excitations is the central theme of …
Covariance Modeling And Space-Time Coding For Mimo Systems, Farnaz Karimdady Sharifabad
Covariance Modeling And Space-Time Coding For Mimo Systems, Farnaz Karimdady Sharifabad
Theses and Dissertations
The full spatial covariance matrix of the multiple input multiple-output (MIMO) channel is an important quantity in channel modeling, communication system signal processing, and performance analysis, and therefore this matrix forms the heart of the research outlined in this dissertation. The work begins with an investigation of a generalized framework for computing the full MIMO spatial covariance based on the power angular spectrum (PAS) of the multipath field and the transmit and receive antenna element radiation patterns. For the case of uniform linear arrays and when the PAS clusters satisfy uniform, truncated Gaussian, or truncated Laplacian distributions, a series expansion …
Overloaded Satellite Receiver Using Sic With Hybrid Beamforming And Ml Detection, Zohair Abu-Shaban, Hani Mehrpouyan, Joel Grotz, Björn Ottersten
Overloaded Satellite Receiver Using Sic With Hybrid Beamforming And Ml Detection, Zohair Abu-Shaban, Hani Mehrpouyan, Joel Grotz, Björn Ottersten
Hani Mehrpouyan
In this paper, a new receiver structure that is intended to detect the signals from multiple adjacent satellites in the presence of other interfering satellites is proposed. We tackle the worst case interference conditions, i.e., it is assumed that uncoded signals that fully overlap in frequency arrive at a multiple-element small-size parabolic antenna in a spatially correlated noise environment. The proposed successive interference cancellation (SIC) receiver, denoted by SIC Hy/ML, employs hybrid beamforming and disjoint maximum likelihood (ML) detection. Depending on the individual signals spatial position, the proposed SIC Hy/ML scheme takes advantage of two types of beamformers: a …
Improved Methods For Phased Array Feed Beamforming In Single Dish Radio Astronomy, Michael James Elmer
Improved Methods For Phased Array Feed Beamforming In Single Dish Radio Astronomy, Michael James Elmer
Theses and Dissertations
Among the research topics needing to be addressed to further the development of phased array feeds (PAFs) for radio astronomical use are challenges associated with calibration, beamforming, and imaging for single dish observations. This dissertation addresses these concerns by providing analysis and solutions that provide a clearer understanding of the effort required to implement PAFs for complex scientific research. It is shown that calibration data are relatively stable over a period of five days and may still be adequate after 70 days. A calibration update system is presented with the potential to refresh old calibrators. Direction-dependent variations have a much …
Dsp-Based Implementation Of A Real-Time Doa Estimator For Underwater Acoustic Sources, Sheng-Yun Hou, Shun-Hsyung Chang, Hsien-Sen Hung, Jiang-Yao Chen
Dsp-Based Implementation Of A Real-Time Doa Estimator For Underwater Acoustic Sources, Sheng-Yun Hou, Shun-Hsyung Chang, Hsien-Sen Hung, Jiang-Yao Chen
Journal of Marine Science and Technology
Many direction-of-arrival (DOA) estimation algorithms for acoustic sources based on sensor array measurements have been well developed and verified via computer simulations and/or small-scale water trough experiments. However, these results are not in practical use because the testing scenarios may not reflect real underwater environments. In order to have a better understanding of DOA estimation in sea experiments, a prototype of DSP-based acoustic DOA estimator is designed and implemented. The prototype system is based on TMS320VC33 digital signal processor and is validated by both computer simulation and experiments performed on the shallow water of Bi-Sha fishery harbor located near the …
Reduced-Feedback Linear Precoding With Stable Performance For The Time-Varying Mimo Broadcast Channel, Michael A. Jensen, Adam L. Anderson, James R. Zeidler
Reduced-Feedback Linear Precoding With Stable Performance For The Time-Varying Mimo Broadcast Channel, Michael A. Jensen, Adam L. Anderson, James R. Zeidler
Faculty Publications
This work explores the performance of a multiple-input multiple-output broadcast channel where both the transmitter and receivers have outdated channel knowledge due to node motion or other time-variations in the communication channel. A performance analysis based on measured channel responses reveals significant throughput degradation for optimal linear and nonlinear precoding strategies unless the channel state information (CSI) is frequently fed back to the transmitter. The paper then develops a linear beamforming precoding strategy based on channel distribution information in the form of a full spatial correlation matrix for each user. This algorithm is shown to provide highly stable communication, with …
Cross-Layer Issues In Mac Protocol Design For Mimo Ad Hoc Networks, Michael A. Jensen, A. Lee Swindlehurst, Michele Zorzi, James R. Zeidler, Adam L. Anderson, Bhaskar Rao, John Proakis, Srikanth Krishnamurthy
Cross-Layer Issues In Mac Protocol Design For Mimo Ad Hoc Networks, Michael A. Jensen, A. Lee Swindlehurst, Michele Zorzi, James R. Zeidler, Adam L. Anderson, Bhaskar Rao, John Proakis, Srikanth Krishnamurthy
Faculty Publications
In this article, we discuss research and design issues that arise in the development of networking protocols for an ad hoc network where nodes are equipped with multiple antenna elements and have the ability to perform signal processing operations as required by adaptive beamforming, interference cancellation, and space-time coding.
Transmission Strategies For Wireless Multi-User, Multiple-Input, Multiple-Output Communication Channels, Quentin H. Spencer
Transmission Strategies For Wireless Multi-User, Multiple-Input, Multiple-Output Communication Channels, Quentin H. Spencer
Theses and Dissertations
Multiple-Input, Multiple-Output (MIMO) processing techniques for wireless communication are of interest for next-generation systems because of their potential to dramatically improve capacity in some propagation environments. When used in applications such as wireless LAN and cellular telephony, the MIMO processing methods must be adapted for the situation where a base station is communicating with many users simultaneously. This dissertation focuses on the downlink of such a channel, where the base station and all of the users have antenna arrays. If the transmitter has advance knowledge of the users' channel transfer functions, it can use that information to minimize the interuser …
Combined Beamforming And Space-Time Block Coding With A Sparse Array Antenna, Robert H. Morelos-Zaragoza, Mohammad Ghavami
Combined Beamforming And Space-Time Block Coding With A Sparse Array Antenna, Robert H. Morelos-Zaragoza, Mohammad Ghavami
Faculty Publications
We continue our investigation of joint beamforming and transmit diversity with space-time block coding. In particular, the performance of a four-element array antenna is considered, in the context of an indoor wireless communication system. The main contribution is to show that transmit diversity may be practically achieved, even with correlated beams produced by a sparse array antenna.
Cramér-Rao Bounds For Estimating Range, Velocity, And Direction With An Active Array, Aleksandar Dogandžić, Arye Nehorai
Cramér-Rao Bounds For Estimating Range, Velocity, And Direction With An Active Array, Aleksandar Dogandžić, Arye Nehorai
Aleksandar Dogandžić
We derive Cramer-Rao bound (CRB) expressions for the range (time delay), velocity (Doppler shift), and direction of a point target using an active radar or sonar array. First, general CRB expressions are derived for a narrowband signal and array model and a space-time separable noise model that allows both spatial and temporal correlation. We discuss the relationship between the CRB and ambiguity function for this model. Then, we specialize our CRB results to the case of temporally white noise and the practically important signal shape of a linear frequency modulated (chirp) pulse sequence. We compute the CRB for a three-dimensional …
Estimating Evoked Dipole Responses In Unknown Spatially Correlated Noise With Eeg/Meg Arrays, Aleksandar Dogandžić, Arye Nehorai
Estimating Evoked Dipole Responses In Unknown Spatially Correlated Noise With Eeg/Meg Arrays, Aleksandar Dogandžić, Arye Nehorai
Aleksandar Dogandžić
We present maximum likelihood (ML) methods for estimating evoked dipole responses using electroencephalography (EEG) and magnetoencephalography (MEG) arrays, which allow for spatially correlated noise between sensors with unknown covariance. The electric source is modeled as a collection of current dipoles at fixed locations and the head as a spherical conductor. We permit the dipoles' moments to vary with time by modeling them as linear combinations of parametric or nonparametric basis functions. We estimate the dipoles' locations and moments and derive the Cramer-Rao bound for the unknown parameters. We also propose an ML based method for scanning the brain response data, …