Ruth Vilar

Q-Band Millimeter-Wave Antennas: An Enabling Technology for MultiGigabit Wireless Backhaul

The bandwidth demands in mobile communication systems are growing exponentially day by day as the number of users has increased drastically over the last five years. This mobile data explosion, together with the fixed service limitations, requires a new approach to support this increase in bandwidth demand. Solutions based on lower-frequency microwave wireless systems may be able to meet the bandwidth demand in a short term. However, with the small-cell mass deployment requiring total capacities of 1 Gb/s/km2, scalable, multigigabit backhaul systems are required. Millimeter-wave technology fits nicely into these new backhaul scenarios as it provides extended bandwidth for high-capacity links and adaptive throughput rate, which allows efficient and flexible deployment. Besides these advantages, millimeter-wave solutions become even more attractive when the cost of backhaul solutions and the cost of spectrum licenses are factored in. Compared to the cost of laying fiber to a cell base station, which is the only other scalable solution, the millimeter-wave solution becomes the most appropriate approach.

All-optical decrementing of a packet’s time-to-live (TTL) field using logic XOR gates

A novel optical time-to-live (TTL) method based on the use of logic XOR gates is proposed. All-optical decrementing of a packet’s TTL field is demonstrated employing a cascade of two SOA-based Mach-Zehnder interferometers. The principle of operation is validated by means of simulations, showing a good extinction ratio (higher than 10 dB) at the output of the 1-bit subtractor.

Millimeter wave wireless system based on point to multipoint transmissions

The continuously growing traffic demand has motivated the exploration of underutilized millimeter wave frequency spectrum for future mobile broadband communication networks. Research activities focus mainly on the use of the V-band (59 - 64 GHz) and E-band (71 - 76 & 81 - 84 GHz) to offer multi-gigabit point to point transmissions. This paper describes an innovative W-band (92-95 GHz) point to multipoint wireless network for high capacity access and backhaul applications. Point to multipoint wireless networks suffer from limited RF power available. The proposed network is based on a high power, wide band traveling wave tube of new generation and an affordable high performance transceiver. These new devices enable a new transmission paradigm and overcome the relevant technological challenges imposed by the high atmosphere attenuation and the presently lack of power amplification required to provide adequate coverage at millimeter waves.

W-band TWTs for new generation high capacity wireless networks

The congestion of the spectrum actually devoted to wireless networks has stimulated the exploitation of the wide availability of frequencies in the millimeter wave range. The high atmospheric attenuation and the strong detrimental rain effect require level of power not available by solid state power amplifiers typically used at microwave frequency. The lack of power has so far limited the use of millimeter wave range. The massive use of Traveling Wave Tubes as power amplifier in high capacity wireless networks will be the breakthrough in the development of the future millimeter wave network fundamental for the 5G development. The H2020 TWEETHER project aims at a new wireless network concept based on TWTs to distribute data in the millimeter wave portion of the spectrum.

Horizon 2020 TWEETHER project for W-band high data rate wireless communications

The outstanding demand of high data rate in wireless network is exceeding the actual capacity making the microwave region of the spectrum inadequate for the future needs. The millimeter wave region has been demonstrated suitable for multi-gigabit transmission. Unfortunately, technological issues still prevent its adequate exploitation. The Horizon 2020 TWEETHER project “Traveling wave tube for W-band wireless networks with high data rate distribution, spectrum and energy efficiency” aims to respond to this challenge. A novel W-band traveling wave tube will be the core of the system.

OSNR monitoring at high-speeds using a FBG-based correlator in optical packet-switched networks

A novel OSNR monitoring technique based on use of optical pulse correlation is demonstrated experimentally. By measuring statistics extracted from the autocorrelation peak, the OSNR is estimated with an error of less than 0.5 dB.

Path monitoring for restoration functions in optical packet-switched networks

The increasing demand in the Internet network for real-time multimedia data traffic with high quality is pushing the limits of existing network structure. Optical packet switching (OPS) is considered as an attractive technology for future optical networks. Due to the high transmission capacity, network management is becoming more and more important. In this context, fault identification and performance monitoring are essential network management functions. In this paper, we propose a monitoring system that not only performs the failure detection, but also assesses the quality of a set of backup paths to infer the network state from the result of a set of end-to-end measurements. This feature allows service providers to establish new or backup paths based on quality requirements. In particular, specific test packets are sent over the supervisory wavelength and processed in the end nodes by means of an optical correlator. Then the optical signal-to-noise ratio (OSNR) of the test packets is estimated from the noise statistics of the autocorrelation pulse peak power. A fiber Bragg grating-based correlator was fabricated to experimentally demonstrate the successful operation. Experiments performed on a 40 Gb/s system confirm the viability of this approach, obtaining direct OSNR monitoring with an error ≪ 0.5 dB.

TWEETHER future generation W-band backhaul and access network technology

Point to multipoint (PmP) distribution at millimeter wave is a frontier so far not yet crossed due to the formidable technological challenge that the high atmospheric attenuation poses. The transmission power at level of tens of Watts required at millimeter wave for a reference range of 1 km is not available by any commercial or laboratory solid state devices. However, the availability of PmP with multigigabit data rate is pivotal for the new high density small cell networks for 4G and 5G and to solve the digital divide in areas where fiber is not convenient or possible to be deployed. In this paper, the advancements of the novel approach proposed by the EU Horizon 2020 TWEETHER project to create the first and fastest outdoor W-band (92 – 95 GHz) PmP wireless network are described. For the first time a new generation W-band traveling wave tube high power amplifier is introduced in the transmission hub to provide the enabling power for a wide area distribution.

TWEETHER project for W-band wireless networks

The European Horizon 2020 project TWEETHER aims to make a breakthrough in wireless networks to overcome the congestion of the actual mobile networks and foster the new 5G networks. A European Consortium including four universities and five companies from four European countries is devoting a relevant effort to realize novel terminals and transmission hubs to operate in the W-band (93–95 GHz). This paper will describe the advancement of the project.

Silicon-based photonic ring resonators for optical OFDM demultiplexing

We propose a compact integrated OOFDM demultiplexer based on silicon-based photonic ring resonators, providing cost-effective solution and low energy consumption. 160-Gb/s OOFDM demultiplexing operation is validated, showing excellent BER performance with error-free operation.