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Title: Techniques for phase noise mitigation in photonic THz wireless systems
Author: Gonzalez Guerrero, Luis
ISNI:       0000 0004 8500 2362
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2019
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Wireless communications at THz frequencies are considered a solution to overcome the spectrum congestion at lower radio frequencies. Photomixing two free-running lasers in an ultra-fast photodiode is an attractive technique for THz generation for its seamless integration with optical networks. However, the THz signal generated with this method can suffer from high phase noise. In the first part of the thesis, the envelope detection of THz single sideband (SSB)-with carrier signals is proposed as the mean to combat such phase noise. Using an ideal envelope detector (ED) at the THz receiver, no significant phase noise penalty is observed in a system operating at 250 GHz and for combined linewidths of up to 1 MHz. The use of interference cancellation algorithms is then proposed as a mean to increase the bandwidth efficiency of the proposed system. Using the Kramers-Kronig algorithm, an efficiency improvement of 38% is achieved with respect to the the case without this algorithm. Next, the performance of three different techniques for generating THz SSB signals is analyzed through numerical simulations and end-to-end implementation of each of them is experimentally demonstrated. According to the simulation, the technique giving better performance is also the one requiring lower analog bandwidth on the transmitter arbitrary waveform generator. This, however, comes at the expense of an increased analog complexity. The second part of this thesis focuses on wireless bridges. To mitigate the phase noise associated with the high number of free-running lasers that form this type of link, the pilot tone-assisted technique is proposed. The wireless bridge is demonstrated in several scenarios: single channel transmission, wavelength division multiplexing network and multiple user support. The last part of this chapter discusses the configuration and DSP to achieve a 40 Gbit/s wireless bridge.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available