H. Bao, F. Ponzini and C. Fager, “Flexible Mm-Wave Sigma-Delta-Over-Fiber MIMO Link”
Abstract: Millimeter-wave and multiple-input-multiple-output (MIMO) technologies combine broad bandwidth with spatial diversity to offer a greater data rate. This paper investigates a flexible millimeter-wave sigma-delta-over-fiber based transmitter solution with digital beamforming MISO and MIMO functionality. Those functions are controlled by a central unit connecting a remote radio head with a standardized QSFP28 fiber link. The central unit generates binary encoded intermediate frequency signals using bandpass sigma-delta modulation. The QSFP28 based fiber link transmits the intermediate frequency bitstreams to the remote radio head. The remote radio head consists of a QSFP28 module, 90∘ hybrids, and upconverters. The remote radio head feeds four parallel, independent, coherent, and central-unit controlled 28 GHz signals to a linear array transmitting antenna. The transmitter performance is experimentally verified, demonstrating up to 800 Msym/s at an EVM/NMSE of 6.7%/-23.5 dB when tested with a 64 quadrature amplitude modulation (64-QAM) modulation scheme. Digital over-the-air beamforming MISO functionality is demonstrated up to 700 Msym/s across 1 m wireless distance. MIMO communication capabilities is demonstrated by over-the-air transmission of two independent 500 Msym/s to two spatially separated receivers. The results show that the proposed link can be used for realization of scalable, low-cost and flexible transmitter solution for emerging distributed antenna systems.
Journal of Lightwave Technology, doi: 10.1109/JLT.2023.3248147.
K. Smirnova, M. V. D. Heijden, X. Yang, K. Giannakidis, D. Leenaerts and A. Ç. Ulusoy, “W -Band 6-Bit Active Phase Shifter Using Differential Lange Coupler in SiGe BiCMOS”
Abstract: This letter presents a W -band vector-modulator-based phase shifter with a 6-bit resolution, implemented in a SiGe:C BiCMOS technology. The phase shifter maintains the RMS amplitude and phase errors lower than 1 dB and 6.6∘ , respectively, for the frequency range of 86–106 GHz without digital calibration. The maximum average gain is 2.3 dB with the 3-dB bandwidth achieving 31 GHz. The circuit consumes 49 mW of power including the phase control circuitry from a 2.4-V supply voltage, 34 mW of which is used by the Gilbert cell. A novel compact differential Lange coupler is used as an IQ splitter. The core part occupies only 0.027 mm2 of the chip area.
IEEE Microwave and Wireless Technology Letters, doi: 10.1109/LMWT.2023.3252633.
Musa Furkan Keskin, Ibrahim Can Sezgin, Husileng Bao, Henk Wymeersch and Christian Fager, “Localization with Distributed MIMO Using a High-Speed Sigma-Delta-over-Fiber Testbed”
Abstract: Distributed MIMO (D-MIMO) with synchronized access points (APs) is a promising architecture for both communications and localization in 5G and beyond systems. In this letter, we develop a time-difference-of-arrival (TDOA)-based indoor localization system using a 2.35-GHz high-speed sigma-delta-over-fiber (SDoF) D-MIMO testbed with 40-MHz bandwidth, exploiting the fully synchronized nature of the APs. Experimental results over an area of size 100 m 2 demonstrate accuracies below 0.2 m and agree with the theoretical Cramér–Rao bounds (CRBs) at most measurement locations, indicating the localization capability of high-speed SDoF D-MIMO.
IEEE Microwave and Wireless Components Letters, vol. 32, no. 7, pp. 923-926, July 2022, doi: 10.1109/LMWC.2022.3157144.
Yingqi Zhang, Artem Vilenskiy, Marianna Ivashina, “Wideband Open-Ended Ridge Gap Waveguide Antenna Elements for 1-D and 2-D Wide-Angle Scanning Phased Arrays at 100 GHz”
Abstract: A new antenna element type based on the open-ended ridge gap waveguide (RGW) is proposed for beam-steering phased array applications. This element type is of a particular interest at high mm-wave frequencies (≥ 100 GHz) owing to a contactless design alleviating active beam-steering electronics integration. The key challenge addressed here is a realization of a wide fractional bandwidth and scan range with high radiation efficiency. We demonstrate a relatively simple wideband impedance matching network comprised of an aperture stepped ridge segment and a single-pin RGW section. Furthermore, the E- and H-plane grooves are added that effectively suppress antenna elements mutual coupling. Results demonstrate a wide-angle beam steering (≥ 50°) over ≥ 20% fractional bandwidth at W-band with ≥ 89% radiation efficiency that significantly outperforms existing solutions at these frequencies. An experimental prototype of a 1×19 W-band array validates the proposed design concept through the embedded element pattern measurements.
IEEE Antennas and Wireless Propagation Letters, vol. 21, no. 5, pp. 883-887, May 2022, doi: 10.1109/LAWP.2022.3150595.