Title:
Dynamic switching of W-band signals for Active and Reconfigurable delivery
Supervisors:
Principal supervisor: Professor Lars Dittmann, DTU Fotonik
Co-supervisor: Assoc. Prof. Tom Keinicke Johansen, DTU Elektro
Co-supervisor: Juan José Vegas Olmos, Mellanox Technologies
Co-supervisor: Jesper Bevensee Jensen, Bifrost Communications
Evaluation Board:
Associate Professor Vitaliy Zhurbenko, DTU Elektro
Professor Viktor Krozer, J. W. Goethe University Frankfurt, Germany
Professor Nikos Pleros, Aristotle University of Thessaloniki, Greece
Master of the Ceremony:
Associate Professor Anders Clausen, DTU Fotonik
Abstract:
The new generation of networks is arriving with new requirements to enhance its capacity, integrate a large number of devices and reduce its latency. These sets of requirements have driven two main changes in the fronthaul. The first is the design of a new kind of access network, in which the main processing and operation is centralized in a central office, instead of being distributed through the base transceiver stations (BTS) or NodeB. The second is the use of new frequency bands, with different countries enabling services proposals in sub-6 GHz bands, in millimeter-wave bands 30-300GHz or both. These two changes come with challenges in signal distribution to the different access points, the generation of the high frequency components and the dynamic behaviour of the communications.
This PhD research focuses on the physical layer of the fronthaul, analysing the transmission of the signal in both the optical and wireless channel, in order to propose reconfigurable systems in the network. The research was carried out in the framework of the EU project Fiber-Wireless Integrated Networks for 5th Generation delivery (FIWIN5G), whose aim is to develop new technologies and concepts in the converged optical fiber networks and wireless radio networks at mm-wave frequencies to provide high bandwidth front/backhaul services and enable scalable and manageable networks without a highly complex interface structure and multiple overlaid protocols.
During this work, Radio-over-Fiber (RoF) is presented as a backbone technology in access networks for communication between the central office and the remote radio head (RRH). In RoF, the wireless signal in directly modulated in the optical channel, allowing the central office to generate and receive the signal of the user equipment (UE). Moreover, by beating the data signal with an optical local oscillator, a super-heterodyne process can be implemented, generating the modulated signal in the desired frequency band. The optical and wireless link between the central office and the UE is analysed in order to find suitable resources to be dynamically switched.
From this study, different proofs of concepts were proposed based in technologies such wavelength and frequency division multiplexing, optical switches and beam steering, between others. These systems and their performance were then individually tested and characterized in order to provide new insight to the already developed state of the art.
The results presented in this thesis serve to lay the groundwork for reconfigurable systems in radio access networks, while defining and contributing to technologies for their implementations. The results verify the viability of these technologies and create the next step on reconfigurable RoF systems for mobile communications.