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BEACHES: Beamspace Channel Estimation for Multi-Antenna mmWave Systems and Beyond
(2019)2019 IEEE 20th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC)Conference Paper -
Finite-Alphabet Wiener Filter Precoding for mmWave Massive MU-MIMO Systems
(2019)2019 53rd Asilomar Conference on Signals, Systems, and ComputersPower consumption of multi-user (MU) precoding is a major concern in all-digital massive MU multiple-input multiple-output (MIMO) base-stations with hundreds of antenna elements operating at millimeter-wave (mmWave) frequencies. We propose to replace part of the linear Wiener filter (WF) precoding matrix by a finite-alphabet WF precoding (FAWP) matrix, which enables the use of low-precision hardware that consumes low power and area. To ...Conference Paper -
Design Trade-offs for Decentralized Baseband Processing in Massive MU-MIMO Systems
(2019)2019 53rd Asilomar Conference on Signals, Systems, and ComputersMassive multi-user (MU) multiple-input multiple- output (MIMO) provides high spectral efficiency by means of spatial multiplexing and fine-grained beamforming. However, conventional base-station (BS) architectures for systems with hundreds of antennas that rely on centralized baseband processing inevitably suffer from (i) excessive interconnect data rates between radio-frequency circuitry and processing fabrics, and (ii) prohibitive ...Conference Paper -
Neural-Network Optimized 1-bit Precoding for Massive MU-MIMO
(2019)2019 IEEE 20th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC)Base station (BS) architectures for massive multiuser (MU) multiple-input multiple-output (MIMO) wireless systems are equipped with hundreds of antennas to serve tens of users on the same time-frequency channel. The immense number of BS antennas incurs high system costs, power, and interconnect bandwidth. To circumvent these obstacles, sophisticated MU precoding algorithms that enable the use of 1-bit DACs have been proposed. Many of these ...Conference Paper -
PPAC: A Versatile In-Memory Accelerator for Matrix-Vector-Product-Like Operations
(2019)2019 IEEE 30th International Conference on Application-specific Systems, Architectures and Processors (ASAP)Processing in memory (PIM) moves computation into memories with the goal of improving throughput and energy-efficiency compared to traditional von Neumann-based architectures. Most existing PIM architectures are either general-purpose but only support atomistic operations, or are specialized to accelerate a single task. We propose the Parallel Processor in Associative Content-addressable memory (PPAC), a novel in-memory accelerator that ...Conference Paper -
Improving Channel Charting with Representation-Constrained Autoencoders
(2019)2019 IEEE 20th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC)Channel charting (CC) has been proposed recently to enable logical positioning of user equipments (UEs) in the neighborhood of a multi-antenna base-station solely from channel-state information (CSI). CC relies on dimensionality reduction of high-dimensional CSI features in order to construct a channel chart that captures spatial and radio geometries so that UEs close in space are close in the channel chart. In this paper, we demonstrate ...Conference Paper -
Siamese Neural Networks for Wireless Positioning and Channel Charting
(2019)2019 57th Annual Allerton Conference on Communication, Control, and Computing (Allerton)Neural networks have been proposed recently for positioning and channel charting of user equipments (UEs) in wireless systems. Both of these approaches process channel state information (CSI) that is acquired at a multi-antenna basestation in order to learn a function that maps CSI to location information. CSI-based positioning using deep neural networks requires a dataset that contains both CSI and associated location information. Channel ...Conference Paper -
Decentralized Coordinate-Descent Data Detection and Precoding for Massive MU-MIMO
(2019)2019 IEEE International Symposium on Circuits and Systems (ISCAS)Massive multiuser (MU) multiple-input multiple-output (MIMO) promises significant improvements in spectral efficiency compared to small-scale MIMO. Typical massive MU-MIMO base-station (BS) designs rely on centralized linear data detectors and precoders which entail excessively high complexity, interconnect data rates, and chip input/output (I/O) bandwidth when executed on a single computing fabric. To resolve these complexity and bandwidth ...Conference Paper -
Are Adversarial Examples Inevitable?
(2019)A wide range of defenses have been proposed to harden neural networks against adversarial attacks. However, a pattern has emerged in which the majority of adversarial defenses are quickly broken by new attacks. Given the lack of success at generating robust defenses, we are led to ask a fundamental question: Are adversarial attacks inevitable? This paper analyzes adversarial examples from a theoretical perspective, and identifies fundamental ...Conference Paper -
PhasePack: A Phase Retrieval Library
(2019)2019 13th International conference on Sampling Theory and Applications (SampTA)Phase retrieval deals with the estimation of complex-valued signals solely from the magnitudes of linear measurements. While there has been a recent explosion in the development of phase retrieval algorithms, the lack of a common interface has made it difficult to compare new methods against the state-of-the-art. The purpose of PhasePack is to create a common software interface for a wide range of phase retrieval algorithms and to provide ...Conference Paper