Marta Beltrán

Ultra-Wideband Radio Signals Distribution in FTTH Networks

The use of an ultra-wideband (UWB) radio technique is proposed as a viable solution for the distribution of high-definition audio/video content in fiber-to-the-home (FTTH) networks. The approach suitability is demonstrated by the transmission of standards-based UWB signals at 1.25 Gb/s along different FTTH fiber links with 25 km up to 60 km of standard single-mode fiber length in a laboratory experiment. Experimental results suggest that orthogonal frequency-division-multiplexed UWB signals exhibit better transmission performance in FFTH networks than impulse radio UWB signals.

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.

Spectral self-imaging effect by time-domain multilevel phase modulation of a periodic pulse train.

We propose and analyze a novel (to our knowledge) approach to implement the spectral self-imaging effect of optical frequency combs. The technique is based on time-domain multilevel phase-only modulation of a periodic optical pulse train. The method admits both infinite- and finite-duration periodic pulse sequences. We show that the fractional spectral self-imaging effect allows one to reduce by an integer factor the comb frequency spacing. Numerical simulation results support our theoretical analysis.

Performance of a 60-GHz DCM-OFDM and BPSK-Impulse Ultra-Wideband System with Radio-Over-Fiber and Wireless Transmission Employing a Directly-Modulated VCSEL

The performance of radio-over-fiber optical transmission employing vertical-cavity surface-emitting lasers (VCSELs), and further wireless transmission, of the two major ultra-wideband (UWB) implementations is reported when operating in the 60-GHz radio band. Performance is evaluated at 1.44 Gbit/s bitrate. The two UWB implementations considered employ dual-carrier modulation orthogonal frequency-division multiplexing (DCM-OFDM) and binary phase-shift keying impulse radio (BPSK-IR) modulation respectively. Optical transmission distances up to 40 km in standard single-mode fiber and up to 500 m in bend-insensitive single-mode fiber with wireless transmission up to 5 m in both cases is demonstrated with no penalty. A simulation analysis has also been performed in order to investigate the operational limits. The analysis results are in excellent agreement with the experimental work and indicate good tolerance to chromatic dispersion due to the chirp characteristics of electro-optical conversion when a directly-modulated VCSEL is employed. The performance comparison indicates that BPSK-IR UWB exhibits better tolerance to optical transmission impairments requiring lower received optical power than its DCM-OFDM UWB counterpart when operating in the 60-GHz band.

60-GHz Ultra-Wideband Radio-Over-Fiber System Using a Novel Photonic Monocycle Generation

An impulse-radio ultra-wideband (UWB) photonic generation system targeting high user density in-flight communications with simultaneous ranging capabilities in the 60-GHz radio band is proposed and demonstrated experimentally and the implementation cost is analyzed. Impulse-radio UWB monocycles are employed for signaling. The monocycles are generated employing a pulsed laser and a differential photoreceiver with phase shifting. Optical frequency up-conversion is performed employing a low-frequency RF carrier and a Mach-Zehnder electrooptical modulator operating in the nonlinear regime. In the experiment, Gaussian monocycles at a 1.244-Gbit/s data rate with 3.8-GHz bandwidth are generated and up-converted to 57 GHz. The performance of the 57-GHz UWB signal after the transmission over a standard single-mode fiber at in-cabin distances up to 100 m is studied. The experimental results show that good quality UWB pulses can be obtained with the proposed system. The impact of the system parameters on performance including wireless transmission and associated cost is analyzed, indicating that a high number of UWB access nodes can be cost-effectively supported by the proposed system.

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.

Optical Distribution of OFDM and Impulse-Radio UWB in FTTH networks

Proposal, experimental demonstration and performance comparison of impulse-radio UWB and OFDM UWB distribution in FTTH networks for high-definition audio/video broadcasting is presented. OFDM-UWB exhibits better performance compared with its impulse- radio counterpart with better spectral efficiency.

Experimental Analysis of 60-GHz VCSEL and ECL Photonic Generation and Transmission of Impulse-Radio Ultra-Wideband Signals

Optical generation of impulse-radio ultra-wideband (UWB) signals in the 60-GHz band is proposed and experimentally demonstrated. External-cavity laser (ECL) and vertical-cavity surface-emitting laser (VCSEL) is employed for frequency up-conversion by heterodyne mixing with a UWB optical signal for comparison purposes. Real-time bit-error-rate (BER) performance of generated signals at 3.125 Gb/s is evaluated combining fiber and 2-m wireless transmission. Different optical fiber types including 1-km bend-insensitive single-mode fiber and 20-km nonzero dispersion-shifted fiber is evaluated. BER <; 10-9 for the ECL and BER <; 2.2·10-3 for the VCSEL requiring higher received optical power than the ECL is demonstrated employing electrical power 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.

60 GHz Radio Over Fiber System Based on Gain-Switched Laser

A radio over fiber (RoF) transmission system based on a gain-switched laser as an optical comb source is proposed and demonstrated. 12.5 Gb/s 16 quadrature amplitude modulation (16 QAM) signal generation and transmission over 25 km standard single-mode fiber is experimentally demonstrated using a 60 GHz carrier. The phase noise of the 60 GHz signal resulting from the beating of two partially phase uncorrelated optical tones is theoretically studied and experimentally investigated. Phase noise comparison with different linewidth comb sources is implemented in the proposed RoF system, and the performance of the various systems with different levels of phase noise is presented.