University of Minnesota

Electronics and Telecommunications Research Institute

National Science Foundation

Georgios B Giannakis

Xiaoli Ma

Shengli Zhou

Liuqing Yang

Yan Xin

Zhengdao Wang

Emiliano Dall'Anese

Gonzalo Mateos

Hao Zhu

Xiliang Luo

Zhiqiang Liu

Sairaj Vijaykumar Dhople

Juan Andres Bazerque

Pengfei Xia

Juan Andrés Bazerque

Techniques are described for carrier frequency offset (CFO) and channel estimation of orthogonal frequency division multiplexing (OFDM) transmissions over multiple-input multiple-output (MIMO) frequency-selective fading channels. A wireless transmitter forms blocks of symbols by inserting training symbols within two or more blocks of information-bearing symbols. The transmitter applies a hopping code to each of the blocks of symbols to insert a null subcarrier at a different position within each of the blocks of symbols, and a modulator outputs a wireless signal in accordance with the blocks of symbols. A receiver receives the wireless signal and estimates the CFO, and outputs a stream of estimated symbols based on the estimated CFO.

Estimating frequency-offsets and multi-antenna channels in MIMO OFDM systems

Decentralized methods for computing optimal real and reactive power setpoints for residential photovoltaic (PV) inverters are described. Optimal power flow techniques are described that select which inverters will provide ancillary services and compute their optimal real and reactive power setpoints according to specified performance criteria and economic objectives.

Decentralized optimal dispatch of photovoltaic inverters in power distribution systems

A semidefinite (SDR) programming formulation for state estimation (SE) of nonlinear AC power systems is described. The techniques make use of convex semidefinite relaxation of the original problem to render the process efficiently solvable. In addition, robust techniques are described that are resilient to outlying measurements and/or adversarial cyber-attacks. Further, techniques for SDR-based SE are described in which local control areas solve the centralized SDP-based SE problem in a distributed fashion.

State estimation of electrical power networks using semidefinite relaxation

This disclosure describes techniques for constructing power spectral density (PSD) maps representative of the distribution of radio frequency (RF) power as a function of both frequency and space (geographic location). For example, the disclosure describes techniques for construction PSD maps using robust basis pursuit forms of signal expansion.

Robust parametric power spectral density (PSD) construction

This disclosure describes techniques for constructing power spectral density (PSD) maps representative of the distribution of radio frequency (RF) power as a function of both frequency and space (geographic location). For example, the disclosure describes techniques for construction PSD maps using non-parametric basis pursuit form of signal expansion.

Non-parametric power spectral density (PSD) map construction

In general, linear complex-field encoding techniques are proposed. For example, transmitter of a wireless communication system includes an encoder and a modulator. The encoder linearly encodes a data stream to produce an encoded data stream. The modulator to produce an output waveform in accordance with the encoded data stream for transmission through a wireless channel. The modulator generates the output waveform as a multicarrier waveform having a set of subcarriers, e.g., an Orthogonal Frequency Division Multiplexing (OFDM) waveform. The encoder linearly encodes the data stream so that the subcarriers carry different linear combinations of information symbols of the data stream.

Wireless communication system having linear encoder

Techniques are described that provide inter-symbol interference&#x2014;(ISI) and multi-user interference&#x2014;(MUI) resilient blind timing synchronization and low complexity demodulation in wireless communication systems. A nonzero mean symbol is transmitted with a predetermined period in a stream of zero mean symbols during a synchronization phase. Only zero mean symbols are transmitted outside of the synchronization phase. Blind or non-data aided synchronization is performed at the receiver while bypassing channel estimation. The techniques enable timing synchronization via energy detection and low-complexity demodulation by matching the received waveform to a synchronized aggregate template (SAT). The SAT is recovered by averaging samples of the received waveform during the synchronization phase. In this manner, the described techniques may be applied to single or multi-user narrowband, wideband, or ultra-wideband (UWB) wireless communication systems with fixed or ad hoc access, but are particularly advantageous for wideband or UWB multi-user ad hoc access.

Growing community of inventors

Minnetonka, MN, United States of America

Georgios B Giannakis