A TDD Distributed MIMO Testbed Using a 1-bit Radio-Over-Fiber Fronthaul Architecture
Journal article, 2024

We present the uplink and downlink of a time-division duplex distributed multiple-input multiple-output (D-MIMO) testbed, based on a 1-bit radio-over-fiber architecture, which is low cost and scalable. The proposed architecture involves a central unit (CU) that is equipped with 1-bit digital-to-analog and analog-to-digital converters, operating at 10 GS/s. The CU is connected to multiple single-antenna remote radio heads (RRHs) via optical fibers, over which a binary radio frequency (RF) waveform is transmitted. In the uplink, a binary RF waveform is generated at the RRHs by a comparator, whose inputs are the received RF signal and a suitably designed dither signal. In the downlink, a binary RF waveform is generated at the CU via bandpass sigma-delta modulation. Our measurement results show that low error-vector magnitude (EVM) can be achieved in both the uplink and the downlink, despite 1-bit sampling at the CU. Specifically, for point-to-point over-cable transmission between a single user equipment (UE) and a CU equipped with a single RRH, we report, for a 10-MBd signal using single-carrier (SC) 16 quadratic-amplitude modulation (QAM) modulation, an EVM of 3.3% in the downlink, and of 4.5% in the uplink. We then consider a CU connected to three RRHs serving over the air two UEs, and show that, after over-the-air reciprocity calibration, a downlink zero-forcing precoder designed on the basis of uplink channel estimates at the CU achieves an EVM of 6.4% and 10.9% at UE 1 and UE 2, respectively. Finally, we investigate the ability of the proposed architecture to support orthogonal frequency-division multiplexing (OFDM) waveforms, and its robustness against both in-band and out-of-band interference.

Modulation

Downlink

Optical fibers

1-bit sampling

radio-over-fiber

Noise

Quantization (signal)

RF signals

Uplink

Distributed multiple-input multiple-output (D-MIMO)

Author

Lise Aabel

Ericsson

Sven Jacobsson

Ericsson

Mikael Coldrey

Ericsson

Frida Olofsson

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

Giuseppe Durisi

Chalmers, Electrical Engineering, Communication, Antennas and Optical Networks

Christian Fager

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

IEEE Transactions on Microwave Theory and Techniques

0018-9480 (ISSN) 15579670 (eISSN)

Vol. In Press

Subject Categories

Telecommunications

Communication Systems

Signal Processing

DOI

10.1109/TMTT.2024.3389151

More information

Latest update

5/23/2024