Fully-photonic digital radio over fibre for future super-broadband access network applications

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel UniversityIn this thesis a Fully-Photonic DRoF (FP-DRoF) system is proposed for deploying of future super-broadband access networks. Digital Radio over Fibre (DRoF) is more independent of the fibre network impairments and the length of fibre than the ARoF link. In order for fully optical deployment of the signal conversion techniques in the FP-DRoF architecture, two key components an Analogue-to-Digital Converter (ADC) and a Digital-to-Analogue Converter (DAC)) for data conversion are designed and their performance are investigated whereas the physical functionality is evaluated. The system simulation results of the proposed pipelined Photonic ADC (PADC) show that the PADC has 10 GHz bandwidth around 60 GHz of sampling rate. Furthermore, by changing the bandwidth of the optical bandpass filter, switching to another band of sampling frequency provides optimised performance condition of the PADC. The PADC has low changes on the Effective Number of Bit (ENOB) response versus analogue RF input from 1 GHz up to 22 GHz for 60 GHz sampling frequency. The proposed 8-Bit pipelined PADC performance in terms of ENOB is evaluated at 60 Gigasample/s which is about 4.1. Recently, different methods have been reported by researchers to implement Photonic DACs (PDACs), but their aim was to convert digital electrical signals to the corresponding analogue signal by assisting the optical techniques. In this thesis, a Binary Weighted PDAC (BW-PDAC) is proposed. In this BW-PDAC, optical digital signals are fully optically converted to an analogue signal. The spurious free dynamic range at the output of the PDAC in a back-to-back deployment of the PADC and the PDAC was 26.6 dBc. For further improvement in the system performance, a 3R (Retiming, Reshaping and Reamplifying) regeneration system is proposed in this thesis. Simulation results show that for an ultrashort RZ pulse with a 5% duty cycle at 65 Gbit/s using the proposed 3R regeneration system on a link reduces rms timing jitter by 90% while the regenerated pulse eye opening height is improved by 65%. Finally, in this thesis the proposed FP-DRoF functionality is evaluated whereas its performance is investigated through a dedicated and shared fibre links. The simulation results show (in the case of low level signal to noise ratio, in comparison with ARoF through a dedicated fibre link) that the FP-DRoF has better BER performance than the ARoF in the order of 10-20. Furthermore, in order to realize a BER about 10-25 for the ARoF, the power penalty is about 4 dBm higher than the FP-DRoF link. The simulation results demonstrate that by considering 0.2 dB/km attenuation of a standard single mode fibre, the dedicated fibre length for the FP-DRoF link can be increased to about 20 km more than the ARoF link. Moreover, for performance assessment of the proposed FP-DRoF in a shared fibre link, the BER of the FP-DRoF link is about 10-10 magnitude less than the ARoF link for -19 dBm launched power into the fibre and the power penalty of the ARoF system is 10 dBm more than the FP-DRoF link. It is significant to increase the fibre link’s length of the FP-DRoF access network using common infrastructure. In addition, the simulation results are demonstrated that the FP-DRoF with non-uniform Wavelength Division Multiplexing (WDM) is more robust against four wave mixing impairment than the conventional WDM technique with uniform wavelength allocation and has better performance in terms of BER. It is clearly verified that the lunched power penalty at CS for DRoF link with uniform WDM techniques is about 2 dB higher than non-uniform WDM technique. Furthermore, uniform WDM method requires more bandwidth than non-uniform scheme which depends on the total number of channels and channels spacing

Analytical Modeling of Self- and Mutual Inductances of DD Coils in Wireless Power Transfer Applications

Self- and mutual inductances are major design parameters for wireless power transfer (WPT) systems. To optimize a WPT system and estimate its performance in terms of received power and efficiency, it is essential to obtain a simple, fast, and accurate calculation of these two parameters. The polarized double-D (DD) coils were selected due to their simplicity of structure, high efficiency, and low sensitivity to misalignment conditions. This paper presents analytical calculations of self- and mutual inductance using the Biot-Savart law for DD coils. The results of the analytical calculations of mutual inductance in different distances between coils were investigated, and the results of the calculations were verified using experimental and finite element method (FEM) simulation results. This paper also presents analytical and FEM-based optimization guidelines for the coupling coefficient of the transmitter coil

A Binary-Weighted Photonic Digital-to-Analogue Converter

In fifth-generation (5G) mobile networks the available bandwidth and the range of carrier frequencies will be significantly larger than in current mobile networks. To cope with the consequent increase in traffic 5G networks will be Digital Radio over Fibre (DRoF) networks for deploying cloud radio access networks (CRAN). As conventional electronic data converters in DRoF networks suffer from jitter at very high giga sampling rates while photonic data converters have better performance, photonic data converters are considered a fundamental building block of a DRoF system for 5G. All Photonic Digital Radio over Fibre (AP-DRoF) is a suitable candidate for carrying future 5G data traffic from a central station for delivery to remote pico-cells. In this paper an 8-Bit binary-weighted Photonic Digital to Analogue Converter (PDAC) for AP-DRoF is proposed for the conversion of an optical bit stream generated by a Photonic Analogue-to-Digital Converter (PADC) into optical analogue signal for delivery to the photo diode of a remote station’s photonic antenna. The potential performance of the proposed PDAC is investigated at a sampling rate of 60 GigaSample/sec through simulation in terms of its Effective Number of Bits (ENOB) and Spurious Free Dynamic Range (SFDR)