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Channel Charting for Streaming CSI Data
(2023)2023 57th Asilomar Conference on Signals, Systems, and ComputersChannel charting (CC) applies dimensionality reduc tion to channel state information (CSI) data at the infrastructure basestation side with the goal of extracting pseudo-position information for each user. The self-supervised nature of CC enables predictive tasks that depend on user position without requiring any ground-truth position information. In this work, we focus on the practically relevant streaming CSI data scenario, in which CSI ...Conference Paper -
The Impact of SAR-ADC Mismatch on Quantized Massive MU-MIMO Systems
(2023)2023 57th Asilomar Conference on Signals, Systems, and ComputersLow-resolution analog-to-digital converters (ADCs) in massive multi-user (MU) multiple-input multiple-output (MIMO) wireless systems can significantly reduce the power, cost, and interconnect data rates of infrastructure basestations. Thus, recent research on the theory and algorithm sides has extensively focused on such architectures, but with idealistic quantization models. However, real-world ADCs do not behave like ideal quantizers, ...Conference Paper -
High Dynamic Range mmWave Massive MU-MIMO with Householder Reflections
(2023)2023 57th Asilomar Conference on Signals, Systems, and ComputersAll-digital massive multiuser (MU) multiple-input multiple-output (MIMO) at millimeter-wave (mmWave) frequencies is a promising technology for next-generation wireless systems. Low-resolution analog-to-digital converters (ADCs) can be utilized to reduce the power consumption of all-digital basestation (BS) designs. However, simultaneously transmitting user equipments (UEs) with vastly different BS-side receive powers either drown weak UEs ...Conference Paper -
Universal MIMO Jammer Mitigation via Secret Temporal Subspace Embeddings
(2023)2023 57th Asilomar Conference on Signals, Systems, and ComputersMIMO processing enables jammer mitigation through spatial filtering, provided that the receiver knows the spatial signature of the jammer interference. Estimating this signature is easy for barrage jammers that transmit continuously and with static signature, but difficult for more sophisticated jammers: Smart jammers may deliberately suspend transmission when the receiver tries to estimate their spatial signature, they may use time-varying ...Conference Paper -
Joint Active User Detection, Channel Estimation, and Data Detection for Massive Grant-Free Transmission in Cell-Free Systems
(2023)2023 IEEE 24th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC)Cell-free communication has the potential to significantly improve grant-free transmission in massive machine-type communication, wherein multiple access points jointly serve a large number of user equipments to improve coverage and spectral efficiency. In this paper, we propose a novel framework for joint active user detection (AUD), channel estimation (CE), and data detection (DD) for massive grant-free transmission in cell-free systems. ...Conference Paper -
DUIDD: Deep-Unfolded Interleaved Detection and Decoding for MIMO Wireless Systems
(2022)2022 56th Asilomar Conference on Signals, Systems, and ComputersIterative detection and decoding (IDD) is known to achieve near-capacity performance in multi-antenna wireless systems. We propose deep-unfolded interleaved detection and decoding (DUIDD), a new paradigm that reduces the complexity of IDD while achieving even lower error rates. DUIDD interleaves the inner stages of the data detector and channel decoder, which expedites convergence and reduces complexity. Furthermore, DUIDD applies deep ...Conference Paper -
Alternating Projections Method for Joint Precoding and Peak-to-Average-Power Ratio Reduction
(2023)Proceedings of 2023 IEEE Conference on Wireless Communications and NetworkingOrthogonal frequency-division multiplexing (OFDM) time-domain signals exhibit high peak-to-average (power) ratio (PAR), which requires linear radio-frequency chains to avoid an increase in error-vector magnitude (EVM) and out-of-band (OOB) emissions. In this paper, we propose a novel joint PAR reduction and precoding algorithm that relaxes these linearity requirements in massive multiuser (MU) multiple-input multiple-output (MIMO) wireless ...Conference Paper -
VLSI Design of a Nonparametric Equalizer for Massive MU-MIMO
(2017)2017 51st Asilomar Conference on Signals, Systems, and ComputersLinear minimum mean-square error (L-MMSE) equalization is among the most popular methods for data detection in massive multi-user multiple-input multiple-output (MU-MIMO) wireless systems. While L-MMSE equalization enables near-optimal spectral efficiency, accurate knowledge of the signal and noise powers is necessary. Furthermore, corresponding VLSI designs must solve linear systems of equations, which requires high arithmetic precision, ...Conference Paper -
Feedforward Architectures for Decentralized Precoding in Massive MU-MIMO Systems
(2018)2018 52nd Asilomar Conference on Signals, Systems, and ComputersMassive multi-user multiple-input multiple-output (MU-MIMO) enables significant gains in spectral efficiency and link reliability compared to conventional, small-scale MIMO technology. In addition, linear precoding using zero forcing or Wiener filter (WF) precoding is sufficient to achieve excellent error-rate performance in the massive MU-MIMO downlink. However, these methods typically require centralized processing at the base-station ...Conference Paper -
MSE-Optimal Neural Network Initialization via Layer Fusion
(2020)2020 54th Annual Conference on Information Sciences and Systems (CISS)Deep neural networks achieve state-of-the-art performance for a range of classification and inference tasks. However, the use of stochastic gradient descent combined with the nonconvexity of the underlying optimization problems renders parameter learning susceptible to initialization. To address this issue, a variety of methods that rely on random parameter initialization or knowledge distillation have been proposed in the past. In this ...Conference Paper