Pilot-Tone Assisted 16-QAM Photonic Wireless Bridge Operating At 250 GHz

Abstract

A photonic wireless bridge operating at a carrier frequency of 250 GHz is proposed and demonstrated. To mitigate the phase noise of the free-running lasers present in such a link, the tone-assisted carrier recovery is used. Compared to the blind phase noise compensation (PNC) algorithm, this technique exhibited penalties of 0.15 dB and 0.46 dB when used with aggregated Lorentzian linewidths of 28 kHz and 359 kHz, respectively, and 20 GBd 16-quadrature amplitude modulation (QAM) signals. The wireless bridge is also demonstrated in a wavelength division multiplexing (WDM) scenario, where 5 optical channels are generated and sent to the Tx remote antenna unit (RAU). In this configuration, the full band from 224 GHz to 294 GHz is used. Finally, a 50 Gbit/s transmission is achieved with the proposed wireless bridge in single channel configuration. The wireless transmission distance is limited to 10 cm due to the low power emitted by the uni-travelling carrier photodiode used in the experiments. However, link budget calculations based on state-of-the-art THz technology show that distances >1000 m can be achieved with this approach. Index Terms-digital signal processing, broadband communications, microwave photonics, millimeter wave communications, optical mixing, sub-THz communications, wireless bridge.

Photonically Generated Millimetre-Wave and THz Links for Wireless Fronthaul and Backhaul

“…Wireless bridging experiments carried out at 250 GHz [15] have shown only slightly degraded performance compared to that of the demonstrated 50 Gb/s UL configuration at 182 GHz. The IF power required to achieve BER = 3.8 x 10 -3 (7% FEC threshold) with 12.5 Gbaud 16QAM was estimated to be -39 dBm in those experiments.…”

Remote Photonic THZ Generation Using an Optical Frequency Comb and Multicore Fiber

“…The photoreceiver saturation limits the available link budget to short wireless link configurations, adequate for high-performance rack-to-rack communications in datacenters, by example [11]. However, the link distance could be extended using of-the-shelf UTCs and different antenna configurations [22]. For example, using an antenna-integrated UTC [23] and 4×1 antenna array [24], a wireless distance of 5.9 m could be reached (or even 7 m if a 20%-overhead soft-decision SD-FEC is considered, i.e.…”

“…A 5 to 7 m wireless reach would be enough for indoor access in wireless local or personal access networks (WLAN or WPAN). However, longer distances could also be reached using state-of-the-art THz amplification [25] and a Cassegrain antenna with 55 dBi gain [26], providing a coverage of up to 1200 m (or up to 1350 m considering SD-FEC) even in a heavy-rain scenario [22].…”

180 Gbps Multi-Channel 300 GHz Communications Enabled by Photonically-Driven Low-Barrier Mixers

“…To do this, the carrier and one of the sidebands are filtered and mixed digitally, canceling common phase noise as a result. This would be similar to the pilot-tone-assisted technique proposed in [50] but using the intrinsic carrier in the system. We refer to this approach as the Carrier-assisted DSP (CA-DSP), and to Blind Carrier Phase Estimation DSP (BCPE-DSP) in the opposite case.…”