Xiaodan Pang

100 Gbit/s hybrid optical fiber-wireless link in the W-band (75–110 GHz)

We experimentally demonstrate an 100 Gbit/s hybrid optical fiber-wireless link by employing photonic heterodyning up-conversion of optical 12.5 Gbaud polarization multiplexed 16-QAM baseband signal with two free running lasers. Bit-error-rate performance below the FEC limit is successfully achieved for air transmission distances up to 120 cm.

25 Gbit/s QPSK Hybrid Fiber-Wireless Transmission in the W-Band (75–110 GHz) With Remote Antenna Unit for In-Building Wireless Networks

In this paper, we demonstrate a photonic up-converted 25 Gbit/s fiber-wireless quadrature phase shift-keying (QPSK) data transmission link at the W-band (75-110 GHz). By launching two free-running lasers spaced at 87.5 GHz into a standard single-mode fiber (SSMF) at the central office, a W-band radio-over-fiber (RoF) signal is generated and distributed to the remote antenna unit (RAU). One laser carries 12.5 Gbaud optical baseband QPSK data, and the other acts as a carrier frequency generating laser. The two signals are heterodyne mixed at a photodetector in the RAU, and the baseband QPSK signal is transparently up-converted to the W-band. After the wireless transmission, the received signal is first down-converted to an intermediate frequency (IF) at 13.5 GHz at an electrical balanced mixer before being sampled and converted to the digital domain. A digital-signal-processing (DSP)-based receiver is employed for offline digital down-conversion and signal demodulation. We successfully demonstrate a 25 Gbit/s QPSK wireless data transmission link over a 22.8 km SSMF plus up to 2.13 m air distance with a bit-error-rate performance below the 2 × 10-3 forward error correction (FEC) limit. The proposed system may have the potential for the integration of the in-building wireless networks with the fiber access networks, e.g., fiber-to-the-building (FTTB).

Fiber Wireless Transmission of 8.3-Gb/s/ch QPSK-OFDM Signals in 75–110-GHz Band

In this letter, we present a scalable high-speed W-band (75-110-GHz) fiber wireless communication system. By using an optical frequency comb generator, three-channel 8.3-Gb/s/ch optical orthogonal frequency-division-multiplexing (OOFDM) baseband signals in a 15-GHz bandwidth are seamlessly translated from the optical to the wireless domain. The W-band wireless carrier is generated from heterodyne mixing the OOFDM baseband signal with a free-running laser. A W-band electronic down-converter and a digital signal processing-based receiver are used. Three-channel QPSK-OFDM W-band wireless signals are transmitted over 0.5- and 2-m air distance with and without 22.8-km single-mode fiber, respectively, with achieved performance below the forward error correction limit.

Feasibility Study and Experimental Verification of Simplified Fiber-Supported 60-GHz Picocell Mobile Backhaul Links

We propose and experimentally demonstrate a fiber-wireless transmission system for optimized delivery of 60-GHz radio frequency (RF) signals through picocell mobile backhaul connections. We identify advantages of 60-GHz links for utilization in short-range mobile backhaul through feasibility analysis and comparison with an alternative E-band (60-90 GHz) technology. The 60-GHz fiber-wireless-fiber setup is then introduced: two spans of up to 20 km of optical fiber are deployed and bridged by up to 4 m of wireless distance. The 60-GHz radio-over-fiber technology is utilized in the first span of fiber transmission. The system is simplified and tailored for delivery of on-off keying data signals by employing a single module for lightwave generation and modulation combined with a simplified RF downconversion technique by envelope detection. Data signals of 1.25 Gb/s are transmitted, and a bit-error-rate performance below the 7% overhead forward-error-correction limit is achieved for a range of potential fiber deployment scenarios. A spurious free dynamic range of 73 dB-Hz2/3 is attained for a frequency-doubling photonic RF upconversion technique. The power budget margin that is required to extend the wireless transmission distance from 4 m to a few hundred meters has been taken into account in the setup design, and the techniques to extend the wireless distance are analyzed.

2x2 MIMO-OFDM Gigabit fiber-wireless access system based on polarization division multiplexed WDM-PON

We propose a spectral efficient radio over wavelength division multiplexed passive optical network (WDM-PON) system by combining optical polarization division multiplexing (PDM) and wireless multiple input multiple output (MIMO) spatial multiplexing techniques. In our experiment, a training-based zero forcing (ZF) channel estimation algorithm is designed to compensate the polarization rotation and wireless multipath fading. A 797 Mb/s net data rate QPSK-OFDM signal with error free (<1 × 10(5)) performance and a 1.59 Gb/s net data rate 16QAM-OFDM signal with BER performance of 1.2 × 10(2) are achieved after transmission of 22.8 km single mode fiber followed by 3 m and 1 m air distances, respectively.

Phase noise tolerance study in coherent optical circular QAM transmissions with Viterbi-Viterbi carrier phase estimation

We present a performance evaluation of a non-conventional approach to implement phase noise tolerant optical systems with multilevel modulation formats. The performance of normalized Viterbi-Viterbi carrier phase estimation (V-V CPE) is investigated in detail for circular m-level quadrature amplitude modulation (C-mQAM) signals. The intrinsic property of C-mQAM constellation points with a uniform phase separation allows a straightforward employment of V-V CPE without the need to adapt constellation. Compared with conventional feed-forward CPE for square QAM signals, the simulated results show an enhanced tolerance of linewidth symbol duration product (ΔνTs) at a low sensitivity penalty by using feed-forward CPE structure with C-mQAM. This scheme can be easily upgraded to higher order modulations without inducing considerable complexity.

Ultra-Broadband Photonic Harmonic Mixer Based on Optical Comb Generation

We propose a novel photonic harmonic mixer operating at frequencies up to the millimeter-wave (MMW) band. By combining a broadband fiber-wireless signal with high-order harmonics of a fundamental local oscillator in an optical frequency comb generator, frequency down-conversion can be implemented without using a costly ultra-broadband photodiode. It is theoretically shown that the down-conversion efficiency and the bandwidth of the mixer is highly dependent on the optical modulation indices and the fundamental frequency of comb lines. Down-conversion of a W -band (75-110 GHz) fiber-wireless signal is experimentally demonstrated. Moreover, the error vector magnitude (EVM) performance of a multigigabit quadrature phase-shift-keying (QPSK) signal at 62.5-, 82.5-, and 102.5-GHz carrier frequencies is studied to evaluate the down-conversion efficiency. The proposed photonic harmonic mixer can be a candidate for applications in high capacity fiber-wireless communication systems.

Hybrid optical fibre-wireless links at the 75–110 GHz band supporting 100 Gbps transmission capacities

We present a photonic generation and down-conversion method for realizing a 40Gbps wireless link at the 75–110 GHz band exploiting the recent advances in photonic coherent detection technologies and digital signal processing. Furthermore, we analyze the capacities of hybrid optical fiber-wireless links at the 75–110GHz band, and propose several approaches to overcome the challenges towards 100Gbps wireless capacity.

High phase noise tolerant pilot-tone-aided DP-QPSK optical communication systems.

In this paper we experimentally demonstrate a novel, high phase-noise tolerant, optical dual polarization (DP) quadrature phase-shift keying (QPSK) communication system based on pilot-tone-aided phase noise cancellation (PNC) algorithm. Vertical cavity surface emitting lasers (VCSELs) with approximate 300 MHz linewidth are used as transmitters and local oscillators for coherent detection of optical DP-QPSK signals. The proposed system, with central wavelength at 1540.68 nm, operates at 40 Gb/s over 80 km single mode fiber (SMF) as part of a passive optical network (PON). The deployment of pilot-tone-aided PNC algorithm guarantees a bit error rate (BER) performance below the forward error correction (FEC) threshold. Moreover, we also evaluate a novel digital signal processing (DSP) algorithm for adaptive pilot tone detection.

Single- and Multiband OFDM Photonic Wireless Links in the 75−110 GHz Band Employing Optical Combs

The photonic generation of electrical orthogonal frequency-division multiplexing (OFDM) modulated wireless signals in the 75-110 GHz band is experimentally demonstrated employing in-phase/quadrature electrooptical modulation and optical heterodyn upconversion. The wireless transmission of 16-quadrature-amplitude-modulation OFDM signals is demonstrated with a bit error rate performance within the forward error correction limits. Signals of 19.1 Gb/s in 6.3-GHz bandwidth are transmitted over up to 1.3-m wireless distance. Optical comb generation is further employed to support different channels, allowing the cost and energy efficiency of the system to be increased and supporting different users in the system. Four channels at 9.6 Gb/s/ch in 14.4-GHz bandwidth are generated and transmitted over up to 1.3-m wireless distance. The transmission of a 9.6-Gb/s single-channel signal occupying 3.2-GHz bandwidth over 22.8 km of standard single-mode fiber and 0.6 m of wireless distance is also demonstrated in the multiband system.