Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 8 of 8
Full-Text Articles in Engineering
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the performance of a multiple-input multiple-output broadcast channel where both the transmitter and receivers have outdated channel knowledge due to node motion or other time-variations in the communication channel.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.
Network Model For Mimo Systems With Coupled Antennas And Noisy Amplifiers, Michael A. Jensen, Matthew L. Morris
Network Model For Mimo Systems With Coupled Antennas And Noisy Amplifiers, Michael A. Jensen, Matthew L. Morris
Faculty Publications
This work presents a framework for the analysis of mutually-coupled antennas in a multiple-input multiple-output system. The approach uses network theory to formulate the transfer matrix relating the signals input to the transmit antennas to the signals at the output of the receiver front end. This transfer function includes the coupled transmit and receive antennas, the multipath propagation channel, the receiver matching network, and a realistic noise model for the receive amplifiers. Application of the formulation to coupled dipole antennas characterized using full-wave electromagnetic analysis illustrates the performance gains possible from matching the coupled antenna/receive amplifier subsystem for minimum noise …
Efficient Capacity-Based Antenna Selection For Mimo Systems, Michael A. Jensen, Matthew L. Morris
Efficient Capacity-Based Antenna Selection For Mimo Systems, Michael A. Jensen, Matthew L. Morris
Faculty Publications
The achieved capacity of the multiple-input-multiple-output wireless channel is typically dependent on the array configurations at the transmitter and receiver. Maximizing system capacity or throughput therefore requires that the arrays adapt to changing channel conditions, which may be accomplished by selecting an appropriate subset of available antenna elements for connection to the electronic transmit and receive modules. This work presents algorithms, derived using relatively straightforward information theoretic considerations, for efficiently and effectively selecting the antenna elements. Computational examples using a realistic channel model for indoor environments illustrate the performance of the techniques.
Mutual Coupling In Mimo Wireless Systems: A Rigorous Network Theory Analysis, Michael A. Jensen, Jon W. Wallace
Mutual Coupling In Mimo Wireless Systems: A Rigorous Network Theory Analysis, Michael A. Jensen, Jon W. Wallace
Faculty Publications
A new framework for the analysis of multiple-input multiple-output (MIMO) wireless systems is introduced to account for mutual coupling effects in the antenna arrays. The multiport interactions at transmit and receive are characterized by representing the channel using a scattering parameter matrix. A new power constraint that limits the average radiated power is also introduced. The capacity of the MIMO system with mutual coupling is defined as the maximum mutual information of the transmit and receive vectors over all possible transmit signaling and receive loading. Full-wave electromagnetic antenna simulations combined with a simple path-based channel model are used to demonstrate …
Analysis Of Electromagnetic Field Polarizations In Multi-Antenna Systems, Michael A. Jensen, Jon W. Wallace, Thomas Svantesson
Analysis Of Electromagnetic Field Polarizations In Multi-Antenna Systems, Michael A. Jensen, Jon W. Wallace, Thomas Svantesson
Faculty Publications
This paper provides an analytical framework useful for assessing the use of all six electric and magnetic electromagnetic field polarizations for multiantenna communications systems. The approach uses a mapping between the induced signal currents and the received electromagnetic field in order to formulate a diversity interpretation of the six-polarization problem. Application of the framework to a simple, yet representative, channel model demonstrates that for full multipath elevation and azimuthal angle spread, six communication modes are theoretically possible. However, to implement the system requires more antenna design work since a straightforward implementation is found to reduce the potential number of modes …
Experimental Characterization Of The Mimo Wireless Channel: Data Acquisition, Analysis, And Modeling, Michael A. Jensen, Jon W. Wallace, A. Lee Swindlehurst, Brian D. Jeffs
Experimental Characterization Of The Mimo Wireless Channel: Data Acquisition, Analysis, And Modeling, Michael A. Jensen, Jon W. Wallace, A. Lee Swindlehurst, Brian D. Jeffs
Faculty Publications
Detailed performance assessment of space-time coding algorithms in realistic channels is critically dependent upon accurate knowledge of the wireless channel spatial characteristics. This paper presents an experimental measurement platform capable of providing the narrowband channel transfer matrix for wireless communications scenarios. The system is used to directly measure key multiple-input-multiple-output parameters in an indoor environment at 2.45 GHz. Linear antenna arrays of different sizes and construction with up to ten elements at transmit and receive are utilized in the measurement campaign. This data is analyzed to reveal channel properties such as transfer matrix element statistical distributions and temporal and spatial …
Modeling The Indoor Mimo Wireless Channel, Michael A. Jensen, Jon W. Wallace
Modeling The Indoor Mimo Wireless Channel, Michael A. Jensen, Jon W. Wallace
Faculty Publications
This paper demonstrates the ability of a physically based statistical multipath propagation model to match capacity statistics and pairwise magnitude and phase distributions of measured 4 x 4 and 10 x 10 narrow-band multiple-input multiple-output data (MIMO) at 2.4 GHz. The model is compared to simpler statistical models based on the multivariate complex normal distribution with either complex envelope or power correlation. The comparison is facilitated by computing channel element covariance matrices for fixed sets of multipath statistics. Multipolarization data is used to demonstrate a simple method for modeling dual-polarization arrays.