A Simulink-based Channel Emulator for Underwater Acoustic Communications

<div>The primary contribution of this paper is to develop a realistic yet mathematically tractable channel emulator for underwater acoustic communications (UWAC) channels. Our proposed emulator is based on the Wide-Sense Stationary Uncorrelated Scattering (WSSUS) assumption, where the channel samples are generated using finite sum-of-sinusoids (SOS) with uniformly distributed phases. The MATLAB-based Simulink platform and its associated block-set elements are used to generate numerical plots for amplitude distribution, Doppler frequency and channel impulse response. This Simulink-based design offers an added advantage over prevalent UWAC channel simulators, as it can be directly adapted to FPGA platform for hardware implementation.</div>

A Simulink-based Channel Emulator for Underwater Acoustic Communications

<div>The primary contribution of this paper is to develop a realistic yet mathematically tractable channel emulator for underwater acoustic communications (UWAC) channels. Our proposed emulator is based on the Wide-Sense Stationary Uncorrelated Scattering (WSSUS) assumption, where the channel samples are generated using finite sum-of-sinusoids (SOS) with uniformly distributed phases. The MATLAB-based Simulink platform and its associated block-set elements are used to generate numerical plots for amplitude distribution, Doppler frequency and channel impulse response. This Simulink-based design offers an added advantage over prevalent UWAC channel simulators, as it can be directly adapted to FPGA platform for hardware implementation.</div>

A Flexible FPGA-Based Channel Emulator for Non-Stationary MIMO Fading Channels

In this paper, a discrete non-stationary multiple-input multiple-output (MIMO) channel model suitable for the fixed-point realization on the field-programmable gate array (FPGA) hardware platform is proposed. On this basis, we develop a flexible hardware architecture with configurable channel parameters and implement it on a non-stationary MIMO channel emulator in a single FPGA chip. In addition, an improved non-stationary channel emulation method is employed to guarantee accurate channel fading and phase, and the schemes of other key modules are also illustrated and implemented in a single FPGA chip. Hardware tests demonstrate that the output statistical properties of proposed channel emulator, i.e., the probability density function (PDF), cross-correlation function (CCF), Doppler power spectrum density (DPSD), and the power delay profile (PDP) agree well with the corresponding theoretical ones.

OTA Testing for Massive MIMO Devices Using Cascaded APM Networks and Channel Emulators

This paper proposes an over-the-air (OTA) testing setup for millimeter-wave (mmWave) massive multiple-input multiple-output (MIMO) equipment using cascaded amplitude and phase modulation (APM) network and channel emulator. Compared with the existing test setup with mechanical switch, the proposed testing setup enables more accurate reconstruction of the radio channel environment under the multiprobe anechoic chamber (MPAC) setup without increasing the number of channel emulators (CEs) to control the system cost. The constructed MPAC testing setup for mmWave and massive MIMO equipment is composed of an anechoic chamber, a sectored probe wall containing a number of probes, an APM network, a fading channel emulator, and a user emulator (UE). In this paper, the structural model and the performance advantages of the proposed radiated testing setup are described, and a fully connected APM network for radiated testing is more prominent than the existing switch. Moreover, the angular spectrum is selected as the performance metric for the reconstructed channel. The ability of the proposed system to reconstruct the power angular spectrum (PAS) of the target channel is studied under both static and dynamic channel models, which can reflect the performance of beamforming procedures of the massive MIMO antenna arrays, e.g., beam acquisition, tracking, and refinement. The simulation results for angular spectrum support the superiority of the proposed OTA testing setup. Furthermore, the simulations for average channel capacity also show that radiated testing setup using cascaded APM network and channel emulator is valid.