Status : Verified
| Personal Name | Decena, Bernalyn A. |
|---|---|
| Resource Title | VCSEL Linearization in 5G New Radio Intensity Modulation-Direct Detection Radio over Fiber Systems using Digital Pre- and Postdistortion Techniques |
| Date Issued | 13 June 2025 |
| Abstract | Nonlinearity in communications systems negatively impacts its performance. In radio over fiber systems, lasers are one of the primary contributors to link nonlinearities. There are existing major techniques in link linearization, namely, hardware compensation, and digital signal processing (DSP). DSP offers promising link performance at a lower cost. Improvements in the computational time and complexity of the system are needed for the system to adapt with the conditions of the link close to real-time. The dissertation aims to characterize and linearize two different Intensity Modulation - Direct Detection RoF systems and analyze the degree of nonlinearity caused by the laser diode. Models are used to create a DSP-aided RoF link linearization, exploring the different techniques: predistortion, postdistortion, and dual compensation. The links are electronically linearized by estimating the predistortion through Memory Polynomial Method (MP) and Generalized Memory Polynomial Method (GMP), improved through the novel implementation of the Improved Cann Model as postdistortion, and a combination of the two techniques through dual compensation. In digital predistortion, ACPR improved by 5 dB, and EVM improved by up to 11%. Memory effects were observed to be mitigated as well in the AM-AM and AM-PM plots. This technique requires initial training and high memory depth with increased computation time and complexity. Performance improvement using the novel digital postdistortion is seen in the EVM of the link, with as much as a 12% difference from the original received OFDM signal, improving the scatter and correcting memory effects. Improvements observed in the system are limited to in-band signals. Dual compensation proposed improved both in-band and out-of-band signals, yielding the best ACPR values, despite having a lower memory depth with approximately 7 dB improvement. Application of the postdistortion reduces computational complexity in the predistorter, lowerin |
| Degree Course | Doctor of Philosophy in Electrical and Electronics Engineering |
| Language | English |
| Keyword | Microwave Photonics; Radio over Fiber; Linearization; Predistortion; Postdistortion; Digital Signal Processing Techniques |
| Material Type | Thesis/Dissertation |
Preliminary Pages
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Category : I - Has patentable or registrable invention of creation.
Access Permission : Limited Access