Jiale He

Experimental investigation of inter-core crosstalk tolerance of MIMO-OFDM/OQAM radio over multicore fiber system

In this paper, the feasibility of space division multiplexing for optical wireless fronthaul systems is experimentally demonstrated by implementing high speed MIMO-OFDM/OQAM radio signals over 20km 7-core fiber and 0.4m wireless link. Moreover, the impact of optical inter-core crosstalk in multicore fibers on the proposed MIMO-OFDM/OQAM radio over fiber system is experimentally evaluated in both SISO and MIMO configurations for comparison. The experimental results show that the inter-core crosstalk tolerance of the proposed radio over fiber system can be relaxed to -10 dB by using the proposed MIMO-OFDM/OQAM processing. These results could guide high density multicore fiber design to support a large number of antenna modules and a higher density of radio-access points for potential applications in 5G cellular system.

Experimental Demonstration of Bidirectional OFDM/OQAM-MIMO Signal Over a Multicore Fiber System

A bidirectional transmission and massive multi-input multi-output (MIMO) enabled radio over a multicore fiber system with centralized optical carrier delivery is experimentally investigated in this paper. Optical carriers for upstream are delivered from the central office to the remote antenna unit via the inner core for the coreless implementation. In our experiment, as one of the fifth-generation (5G) waveform candidates, orthogonal frequency division multiplexing using offset quadrature amplitude modulation (OFDM/OQAM) is adopted in both uplink and downlink to increase the spectral efficiency and side lobes suppression ratio. An advanced 2 × 2 MIMO-OFDM/OQAM channel estimation algorithm is optimally designed to equalize the hybrid optical and wireless MIMO channels. The experimental results show that bidirectional transmission of 4.46 Gb/s 2 × 2 MIMO-OFDM/16-OQAM could be achieved over a 20-km seven-core fiber and a 0.4-m wireless link. The proposed scheme proves that the multicore fiber can realize the transparent transmission of bidirectional radio signals and effectively simplify the infrastructures in the future 5G cellular systems.

Experimental Demonstration of a Novel PON System Using Multi-dimensional CAP-OFDM Technique

We experimentally demonstrate a novel CAP-OFDM-PON system, in which four OFDM channels of 1.25 Gb/s bitrate per channel are multiplexed using four-dimensional CAP filters. Both reliability and flexibility of multiple ONUs’ access have been obtained.

Experimental demonstration of MCF enabled bidirectional colorless CAP-PON system with wavelength reuse technique

A bidirectional transmission with wavelength reuse technique enabled coreless CAP-PON system over multicore fiber is experimentally demonstrated. In the proposed scheme, the ONU side carrier suppression and OLT side coherent detection for a single wavelength implement is adopted for upstream transmission. The optical carrier is delivered from OLT to ONUs in different cores for upstream transmission to avoid Rayleigh backscattering. In our experiment, 10Gb/s symmetrical rate of bidirectional CAP signals is successfully transmitted over 20km MCF.

Experimental demonstration of high spectral efficient 4 × 4 MIMO SCMA-OFDM/OQAM radio over multi-core fiber system

In this paper, 4 × 4 multiple-input multiple-output (MIMO) radio over 7-core fiber system based on sparse code multiple access (SCMA) and OFDM/OQAM techniques is proposed. No cyclic prefix (CP) is required by properly designing the prototype filters in OFDM/OQAM modulator, and non-orthogonally overlaid codewords by using SCMA is help to serve more users simultaneously under the condition of using equal number of time and frequency resources compared with OFDMA, resulting in the increase of spectral efficiency (SE) and system capacity. In our experiment, 11.04 Gb/s 4 × 4 MIMO SCMA-OFDM/OQAM signal is successfully transmitted over 20 km 7-core fiber and 0.4 m air distance in both uplink and downlink. As a comparison, 6.681 Gb/s traditional MIMO-OFDM signal with the same occupied bandwidth has been evaluated for both uplink and downlink transmission. The experimental results show that SE could be increased by 65.2% with no bit error rate (BER) performance degradation compared with the traditional MIMO-OFDM technique.

Employing multicore fiber in short reach optical networks

We employ multicore fibers in short reach optical networks such as optical access network and optical fronthaul system.

2 * 2 MIMO OFDM/OQAM radio signals over an elliptical core few-mode fiber

We experimentally demonstrate a 4.46  Gb/s2×2 multi-input multi-output (MIMO) orthogonal frequency division multiplexing (OFDM)/OQAM radio signal over a 2 km elliptical core 3-mode fiber, together with 0.4 m wireless transmission. Meanwhile, to cope with differential channel delay (DCD) among involved MIMO channels, we propose a time-offset crosstalk cancellation algorithm to extend the DCD tolerance from 10 to 60 ns without using a circle prefix (CP), leading to an 18.7% improvement of spectral efficiency. For the purpose of comparison, we also examine the transmission performance of CP-OFDM signals with different lengths of CPs, under the same system configuration. The proposed algorithm is also effective for the DCD compensation of a radio signal over a 2 km 7-core fiber. These results not only demonstrate the feasibility of space division multiplexing for RoF application but also validate that the elliptical core few-mode fiber can provide the same independent channels as the multicore fiber.

Experimental demonstration of a 10 Gb/s non-orthogonal multi-dimensional CAP-PON system based on the ISI and CCI cancellation algorithm.

The concept of a multi-dimensional carrierless amplitude and phase modulation (CAP) passive optical network (PON) system based on non-orthogonal transceiver filters is presented for the first time, to the best of our knowledge, to improve the spectral efficiency (SE). To eliminate the interferences caused by the non-orthogonal transceiver filters, a novel inter-symbol interference (ISI) and cross-channel interference (CCI) cancellation algorithm (ICCA) is proposed. In our experiment, a 10 Gb/s four-dimensional with four levels/dimension and non-orthogonal CAP data transmission is successfully demonstrated over a 20 km standard single mode fiber. The results indicate that a SE gain from 3.85 to 4.35 bit/s/Hz is achieved by the combination of the proposed ICCA with the traditional modified cascaded multi-modulus and decision-directed least mean square algorithm.