Experimental Demonstration of mm-Wave 5G NR Photonic Beamforming Based on ORRs and Multicore Fiber

[EN] A photonic beamformer system designed for nextgeneration 5G new radio (5G NR) operating in the millimeter waveband is proposed and demonstrated experimentally, including its performance characterization. The photonic beamforming device is based on optical ring resonators (ORRs) implemented on Si3N4 and assisted with multicore fiber (MCF) to feed different antenna elements (AEs). Fast-switching configuration of the ORRs is performed changing the operating wavelength, as tuning the wavelength modifies the coupling coefficient of the rings and, consequently, the induced time delay. Multibeam operation is evaluated at 17.6- and 26-GHz radio keeping the ORRs¿ configuration. The beamforming performance is evaluated using single-carrier signals with up to 128 quadrature amplitude modulation over up to 4.2-GHz electrical bandwidth. The experimental beamforming system with two AEs provides up to 21 Gb/s per user, while the beamforming system with four AEs provides up to 16.8 Gb/s per user. Wireless transmission confirms that changing the wavelength from 1545.200 to 1545.195 nm modifies the beam steering from 11.3° to 23° with 26-GHz signals (5G NR pioneer band in Europe).This work was supported in part by the Fundacion BBVA Leonardo HYPERCONN Project, in part by the Spain National Plan under Grant MINECO/FEDER UE TEC2015-70858-C2-1-R XCORE and Grant GVA AICO/2018/324 NXTIC, and in part by the Dutch FreeBEAM projects. The work of M. Morant was supported by Spain Juan de la Cierva under Grant IJCI-2016-27578. The work of A. Trinidad was supported by Dutch NWO Zwaartekracht Integrated Nanophotonics.Morant, M.; Trinidad, A.; Tangdiongga, E.; Koonen, T.; Llorente, R. (2019). Experimental Demonstration of mm-Wave 5G NR Photonic Beamforming Based on ORRs and Multicore Fiber. IEEE Transactions on Microwave Theory and Techniques. 67(7):2928-2935. https://doi.org/10.1109/TMTT.2019.28944022928293567

Photonic integrated circuits employing multi-core fiber for broadband radio beamsteering (Invited)

This paper presents an optical beamforming network based on a photonic integrated circuit employing a weaklycoupled multi-core fiber to connect the different antenna elements. The proposed beamformer enables a centralized control of the resulting steering angle. By means of wavelength tuning, fast and dynamic configuration of the induced delay (and associated beam steering angle) is achieved remotely. The experimental results confirm high throughput transmission (> 10 Gbps) with electrical data signals with up to 3GHz bandwidth in the 24 GHz RF band (K-band). Wireless transmission of 16QAM-modulated, 1.5 GHz-wide signals is demonstrated in the laboratory from –26˚ to 33˚ providing a scanning range of 59˚

Multi-core fiber technology supporting MIMO and photonic beamforming in 5G multi-antenna systems: (Invited paper)

This paper describes and experimentally validates different multi-Antenna system applications supported by a multicore fiber (MCF) optical fronthaul. The MCF fronthaul enables the simultaneous transmission of different optical data streams at the same wavelength by the spatial multiplexing of multiple-input multiple-output (MIMO) signals. In addition, the MCF enables simultaneous radio beamforming by transmitting the same optical data signal with different phase or time delays to each antenna element. Both MIMO and beamforming capabilities are required for 5G multi-Antenna systems. Experimental demonstrations of 4 \times 4 MIMO transmission and multi-beam 4 \times 1 beamforming using a commercially available 4-core fiber are reported in this work. Optical beam-steering in 5G is achieved using a Si3 N4 photonic chip based on optical ring resonators (ORRs) that enables the continuous and centralized tuning of the time delay applied to each antenna element

Multi-Beamforming Provided by Dual-Wavelength True Time Delay PIC and Multicore Fiber

This paper presents a multi-beamformer based on a dual-wavelength photonic integrated circuit (PIC) and multicore fiber (MCF) capable of providing independent delay tuning to two separate beams modulated on different optical carriers. This implementation enables a centralized control of the photonic beamformer, connecting each element of a phase array antenna with a dedicated core of a MCF link and controlling the induced delay (resulting steering angle) by thermo-optically adjusting the heaters of the PIC. The dual-wavelength PIC implements true time delay (TTD) based on optical ring resonators (ORRs). Six different ORR heaters' configurations are evaluated experimentally, obtaining an induced delay of up to 328 ps at 19 GHz RF. With a measured delay resolution of 4 ps, it is recommended to increase/decrease the delay in small steps (between 10 and 30 ps) in order to keep the switching time in the ms range. Higher delays increments can be induced within longer switching time, e.g. 328 ps requires 1.68 s to stabilize the heaters. The performance demonstration includes the dual-wavelength transmission over 1-km of 7-core MCF and evaluates single-carrier data signals in the K-band centered in 19 GHz RF with up to 4 GHz bandwidth (BW). Operation with OFDM standard WiFi and WiMAX signals is also demonstrated experimentally. A delay of 328 ps can be induced to data signals at 19 GHz RF with up to 3-GHz BW, while 4-GHz BW signals can operate with up to 166 ps delay increment. An almost constant EVM is obtained for each BW below 3 GHz, confirming that changing the beam-steering angle does not affect the quality of the signal

5G NR multi-beam steering employing a photonic TTD chip assisted by multi-core fiber

Beam steering demonstration employing integrated optical ring resonators (ORRs) and multi-core fiber with multiple beams at 17.6 GHz and 26 GHz obtains 103.5° beam separation. A 5G system with 4×1 beamforming at 26 GHz provides up to 16.8 Gbps with 20° beam steering

Dual-wavelength integrated K-band multi-beamformer operating over 1-km 7-core multicore fiber

A dual-wavelength broadband photonic integrated beamformer over 1-km MCF provides independent angles with up to 350 ps increment to 3-GHz or 260 ps to 4-GHz BW signals over two different wavelengths and K-band frequencies

Experimental demonstration of mm-Wave 5G NR photonic beamforming based on ORRs and multicore fiber

A photonic beamformer system designed for next-generation 5G new radio (5G NR) operating in the millimeter waveband is proposed and demonstrated experimentally, including its performance characterization. The photonic beamforming device is based on optical ring resonators (ORRs) implemented on Si3N4 and assisted with multicore fiber (MCF) to feed different antenna elements (AEs). Fast-switching configuration of the ORRs is performed changing the operating wavelength, as tuning the wavelength modifies the coupling coefficient of the rings and, consequently, the induced time delay. Multibeam operation is evaluated at 17.6- and 26-GHz radio keeping the ORRs' configuration. The beamforming performance is evaluated using single-carrier signals with up to 128 quadrature amplitude modulation over up to 4.2-GHz electrical bandwidth. The experimental beamforming system with two AEs provides up to 21 Gb/s per user, while the beamforming system with four AEs provides up to 16.8 Gb/s per user. Wireless transmission confirms that changing the wavelength from 1545.200 to 1545.195 nm modifies the beam steering from 11.3° to 23° with 26-GHz signals (5G NR pioneer band in Europe)

Compact photonic chip assisted by multi-core fiber for radio beamsteering in 5G

This paper describes and evaluates experimentally a Si 3 N 4 photonic chip based on optical ring resonators (ORRs) assisted by multi-core fiber (MCF) that enables radio beamsteering in 5G by the continuous tuning of the time delay applied to an antenna array. Each ORR includes two heaters: one for tuning the resonance wavelength and another to set the coupling coefficient. In this way, the configuration for beamsteering can be implemented by heater tuning or by wavelength shifting. Each optical path of the photonic chip comprises a thermally tunable optical side band filter (OSBF) and an ORR in cascade configuration. The output of each optical path is transmitted through a core of a MCF to distribute the modulated 5G signals to each array element at the transmitter antenna. This ensures that all the optical paths have the same length and enables the delay tuning of each array antenna element directly set from the photonic chip. Experimental demonstration is carried out with a four-core MCF with 26 GHz signals suitable for 5G transmission. </p

Dual-wavelength photonic beamformer for OFDM and single-carrier broadband wireless operating over 1-km 7-core fiber fronthaul

This paper reports a dual-wavelength photonic beamformer implementing optical true time delay (OTTD) to realize microwave beam steering. The beamformer is capable of providing independent delay tuning to two separate beams modulated on different optical carriers. The integrated TTD chip includes a multiplexer that combines the two input wavelengths, an optical sideband filter (OSBF) and optical ring resonators (ORRs) that induce different optical delays. The ORRs are thermo-optically tuned to change the coupling ratio and obtain an incremental delay in each optical path. The experimental demonstration includes a full-compliant WiFi channel (at 5 GHz or 18 GHz RF bands) transmitted in one optical carrier and a WiMAX channel (at 5.4 GHz or 19 GHz RF) in another optical carrier operating in the resonance slope of the ORRs. The different antenna elements are connected with 1-km of 7-core fiber, achieving EVM-compliant levels at the antennas with beam-steering angles ranging from -40° to +80°. The performance comparison considering single-carrier broadband RF signals at the same frequency bands is also reported in this work.</p