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Erich Zöchmann

Publications and source records attributed to Erich Zöchmann.

6 recordsLinked to original sources
arXiv2020

A Bandwidth Scalable Millimetre Wave Over-The-Air Test System with Low Complexity

In this work, we show the design and validation of a testbed for over-the-air testing of millimetre waves equipments. We have extended the frequency capabilities of a baseband channel emulator which is capable of emulating non-stationary channels, to higher frequencies. To assure that the propagation between devices-under-test and the RF-frontend of the emulator is only a line-of-sight link, we have isolated the devices-under-test in two anechoic chambers. We characterize the testbed at 57 GHz by means of frequency sweeps for two artificial cases: when the emulator is replicating a one-tap channel and a two-tap channel. Finally we demonstrate the system functionality through reproduction of channels which were acquired during a vehicular millimetre wave measurement campaign conducted in Vienna in 2018.

eess.SP↗
arXiv2019

Sparsity in the Delay-Doppler Domain for Measured 60 GHz Vehicle-to-Infrastructure Communication Channels

We report results from millimeter wave vehicle-to-infrastructure (V2I) channel measurements conducted on Sept. 25, 2018 in an urban street environment, down-town Vienna, Austria. Measurements of a frequency-division multiplexed multiple-input single-output channel have been acquired with a time-domain channel sounder at 60 GHz with a bandwidth of 100 MHz and a frequency resolution of 5 MHz. Two horn antennas were used on a moving transmitter vehicle: one horn emitted a beam towards the horizon and the second horn emitted an elevated beam at 15-degrees up-tilt. This configuration was chosen to assess the impact of beam elevation on V2I communication channel characteristics: propagation loss and sparsity of the local scattering function in the delay-Doppler domain. The measurement results within urban speed limits show high sparsity in the delay-Doppler domain.

eess.SP↗
arXiv2018

Better than Rician: Modelling millimetre wave channels as Two-Wave with Diffuse Power

This contribution provides experimental evidence for the two-wave with diffuse power (TWDP) fading model. We have conducted two indoor millimetre wave measurement campaigns with directive horn antennas at both link ends. One horn antenna is mounted in a corner of our laboratory, while the other is steerable and scans azimuth and elevation. Our first measurement campaign is based on scalar network analysis with 7 GHz of bandwidth. Our second measurement campaign obtains magnitude and phase information, additionally sampled directionally at several positions in space. %This second measurement campaign is limited to 2 GHz bandwidth. We apply Akaike's information criterion to decide whether Rician fading sufficiently explains the data or the generalized TWDP fading model is necessary. Our results indicate that the TWDP fading hypothesis is favoured over Rician fading in situations where the steerable antenna is pointing towards reflecting objects or is slightly misaligned at line-of-sight. We demonstrate TWDP fading in several different domains, namely, frequency, space, and time.

eess.SP↗
arXiv2015

Exploring the Physical Layer Frontiers of Cellular Uplink - The Vienna LTE-A Simulator

Communication systems in practice are subject to many technical/technological constraints and restrictions. MIMO processing in current wireless communications, as an example, mostly employs codebook based pre-coding to save computational complexity at the transmitters and receivers. In such cases, closed form expressions for capacity or bit-error probability are often unattainable; effects of realistic signal processing algorithms on the performance of practical communication systems rather have to be studied in simulation environments. The Vienna {LTE-A} Uplink Simulator is a 3GPP {LTE-A} standard compliant link level simulator that is publicly available under an academic use license, facilitating reproducible evaluations of signal processing algorithms and transceiver designs in wireless communications. This paper reviews research results that have been obtained by means of the Vienna LTE-A Uplink Simulator, highlights the effects of Single Carrier Frequency Division Multiplexing (as the distinguishing feature to LTE-A downlink), extends known link adaptation concepts to uplink transmission, shows the implications of the uplink pilot pattern for gathering Channel State Information at the receiver and completes with possible future research directions.

cs.IT↗
arXiv2015

Using the LASSO's Dual for Regularization in Sparse Signal Reconstruction from Array Data

Waves from a sparse set of source hidden in additive noise are observed by a sensor array. We treat the estimation of the sparse set of sources as a generalized complex-valued LASSO problem. The corresponding dual problem is formulated and it is shown that the dual solution is useful for selecting the regularization parameter of the LASSO when the number of sources is given. The solution path of the complex-valued LASSO is analyzed. For a given number of sources, the corresponding regularization parameter is determined by an order-recursive algorithm and two iterative algorithms that are based on a further approximation. Using this regularization parameter, the DOAs of all sources are estimated.

math.ST↗