Performance of transmultiplexers based on oversampled filter banks under variable oversampling ratios

In this paper, we explore the influence of oversampling on a filter bank based transmultiplexer, for which previous research has established oversampling as a useful mean to ease synchronisation. The effect of oversampling is assessed mainly in terms of inter-symbol interference due to synchronisation errors and due to the residual time-dispersive effect of the transmission medium after transmultiplexing. Both effects can be targetted by a fractionally spaced equaliser. Although the achievable minimum mean square error is lower for higher oversampling ratios, we show by example of a powerline communications channel that slow convergence of least mean square type adaptive equalisers prohibits the exploitation of this benefit. Together with considerations on bandwidth efficiency and peak-to-average power ratio, it is advantageous to keep the oversampling ratio as small as possible.