Lecturer Profile |
Stephen McLaughlin received the B.Sc. degree in Electronics and Electrical Engineering from the University of Glasgow in 1981 and the Ph.D. degree from the University of Edinburgh in 1990. From 1981 to 1984 he was a Development Engineer in industry involved in the design and simulation of integrated thermal imaging and fire control systems. From 1984 to 1986 he worked on the design and development of high frequency data communication systems. In 1986 he joined the Dept. of Electronics and Electrical Engineering at the University of Edinburgh as a research fellow where he studied the performance of linear adaptive algorithms in high noise and nonstationary environments. In 1988 he joined the academic staff at Edinburgh, and from 1991 until 2001 he held a Royal Society University Research Fellow ship to study nonlinear signal processing techniques. In 2002 he was awarded a personal Chair in Electronic Communication Systems at the University of Edinburgh. In October 2011 he joined Heriot-Watt University as a Professor of Signal Processing and Head of the School of Engineering and Physical Sciences. His research interests lie in the fields of adaptive signal processing and nonlinear dynamical systems theory and their applications to biomedical, energy and communication systems. Prof McLaughlin is a Fellow of the Royal Academy of Engineering, of the Royal Society of Edinburgh, of the Institute of Engineering and Technology and of the IEEE. |
Lecture Abstract |
The wireless link performance remains profoundly influenced by the presence of the nonlinear high power amplifiers (HPA). While real-time digital predistortion of the transmitted signal can in principle overcome aforementioned impairements, in practice this approach requires impractically high data sample rates and hence is not suitable for high throughput links. Instead data predistortion based on look-up tables is the current recommendation by standards such as the DVB-S2(X) to mitigate HPA non-linearities. Focusing on the aforementioned standard, we analytically and numerically study the end-to-end distortion of the 16APSK constellation from the digital IQ signal at the transmitter across to the non-linear channel and back to the digital IQ signal at the receiver. We demonstrate that the distortion depends not only on the input back off (IBO) of the HPA but, critically, also on the roll off of the digital RRC bandwidth-limiting filters used at the transmitter and receiver. Consequently, we derive informed guidelines for the adaptive operation of the link. The techniques we present can find application in e.g. adaptive operation of a DVB-S2X link with dynamic power control that maintains performance close to optimum by computationally efficient estimation of the combination of MODCOD, RRC roll off and IBO operation on a given HPA. |
