Alexander Lebedev

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.

A novel method for combating dispersion induced power fading in dispersion compensating fiber.

We experimentally investigate the performance of 60 GHz double sideband (DSB) radio over fiber (RoF) links that employ dispersion compensating fiber (DCF). Error free transmission of 3 Gbps signals over 1 m of wireless distance is reported. In order to overcome experimentally observed chromatic dispersion (CD) induced power fading of radio frequency (RF) signal, we propose a method for improvement of RF carrier-to-noise (C/N) ratio through introduction of a degree of RF frequency tunability. Overall results improve important aspects of directly modulated RoF systems and demonstrate the feasibility of high carrier frequency and wide bandwidth RF signals delivery in RoF links including DCF fiber. Error free performance that we obtain for 3 Gbps amplitude shift-keying (ASK) signals enables uncompressed high-definition 1080p video delivery.

Demonstration and Comparison Study for V- and W-Band Real-Time High-Definition Video Delivery in Diverse Fiber-Wireless Infrastructure

Abstract This article experimentally demonstrates uncompressed high-definition video distribution in V-band (50–75 GHz) and W-band (75–110 GHz) fiber-wireless links achieving 3 m of wireless transmission in both cases. Access architecture is experimentally emulated by deploying single/multi-mode fibers. For the W-band, experimental assessment of passive and active approaches for implementation of remote antenna units is reported. The bit error rate performance of the optical and wireless channels is reported. A successful transmission of real-time uncompressed high-definition video in the V- and W-band fiber-wireless systems is demonstrated with prospects to pave the way for application-focused fiber-wireless connectivity.

A 15-meter multi-gigabit W-band bidirectional wireless bridge in fiber-optic access networks

We present a bidirectional wireless bridge in the W-band enabling the seamless convergence between the wireless and fiber-optic access networks. In the downlink, a 16 Gbit/s QPSK signal is photonically up-converted at the wireless transmitter and electrically down-converted at the wireless receiver. The down-converted signal is re-modulated on to the lightwave and transmit further through the fiber-optic system. In the uplink, both up-and down-conversion are performed by electrical means. Furthermore, we investigate both passive and active wireless transmitters in this work for both downlink and uplink transmissions. With an active wireless transmitter, up to 15 meters wireless transmission is successfully achieved with a BER below the 7% FEC limit in the downlink.

Multigigabit W-Band (75–110 GHz) Bidirectional Hybrid Fiber-Wireless Systems in Access Networks

We experimentally demonstrate multigigabit capacity bidirectional hybrid fiber-wireless systems with RF carrier frequencies at the W-band (75-110 GHz) that enables the seamless convergence between wireless and fiber-optic data transmission systems in access networks. In this study, we evaluate the transmission performances in two scenarios: a fiber-wireless access link that directly provide high-speed connections to wireless end users, and a fiber-wireless-fiber signal relay where a high capacity wireless link can be used to bridge two access fiber spans over physical obstacles. In both scenarios, we compare the transmission performances in terms of achievable wireless distances with and without using a high-frequency electrical power amplifier at the wireless transmitter. A downlink 16-Gbit/s QPSK signal and an uplink 1.25-Gbit/s ASK signal transmission over the two implementations are experimentally evaluated in terms of bit-error-rate (BER) performance. Results show that the use of the power amplifier can extend the wireless distance from ~1 m to over 15 m in an indoor environment with BER performance within the 7% FEC threshold.

Simultaneous 60-GHz RoF Transmission of Lightwaves Emitted by ECL, DFB, and VCSEL

Simultaneous 60-GHz radio over fiber upconversion and fiber transmission of lightwaves produced by an external cavity laser, a distributed feedback laser, and a C-band vertical cavity surface emitting laser are demonstrated. The 1.25-Gb/s data are transmitted concurrently on each of the lightwaves attaining a bit error rate performance <10-9 level. Carrier suppression of 20 dB is achieved for all three lightwaves placed in a wide wavelength range. The 10-9 receiver sensitivity level for detection of three lightwaves falls in a <3-dB region. Reported close performance of the investigated techniques enables diversification of options for lightwave generation in millimeter-wave fiber-wireless networks.

Gigabit close-proximity wireless connections supported by 60 GHz RoF links with low carrier suppression

We present an experimental investigation of the 60 GHz optical carrier suppressed radio over fiber systems with less than 5 dB carrier suppression. As a case study, the 60 GHz RoF signal is generated using a 12.5 Gb/s commercially available Mach-Zehnder modulator biased at its minimum point. We report on error free transmission over 20 km of standard single mode fiber and 1 m of wireless distance. Furthermore, the efficiency of photonic RF generation depending on the value of carrier suppression is reported. We argue that transport of RoF signals with low carrier suppression assisted with simplified techniques of lightwave generation, baseband data modulation, and RF downconversion might be a promising enabling technology for fiber support of close-proximity wireless terminals.

Tunable photonic RF generator for dynamic allocation and multicast of 1.25 Gbps channels in the 60 GHz unlicensed band

We propose an approach for dynamic channel allocation and multicast data delivery inside the 60 GHz unlicensed band. Channels, conveying 1.25 Gbps signals, can be allocated on demand by tuning the frequency sweep of an external cavity laser (ECL) either in the optical remote node (RN) or in the central office (CO). At the RN, we perform the replication of the original channel suitable for closely spaced multicast applications such as high definition (HD) video delivery where RN serves as a photonic radio frequency (RF) generator for both channel allocation and multicast. Experimental demonstration is presented with bit error rate (BER) performance below 10-9 for original and replicated channels after transmission through 22.8 km of standard single mode fiber (SSMF).

Simplified fiber-wireless distribution of HD video in passive and active W-band close proximity terminals

We experimentally demonstrate uncompressed high-definition (HD) video distribution at 84 GHz Radio over Fiber link achieving up to 3 meters of wireless transmission. We experimentally emulate Metro-Access architecture by deploying single/multimode fibers. Passive and active approaches for remote antenna unit (RAU) are experimentally investigated. The bit error rate (BER) performance of the optical and wireless channels is reported. A successful transmission of uncompressed HD video in the W-band wireless channel is demonstrated with prospects to pave the way for application-focused fiber-wireless connectivity supported by diverse optical fiber distribution infrastructure.