Design of Improvements to Low-Complexity Scheme for Enhancing Multi Carrier Communications
Abstract:
The paper describes an enhanced version of a scheme originally designed by the current author (and discussed in an earlier IET paper) to enable one to improve the quality of one’s own wireless communications, over a given frequency (or frequencies), when in the presence of inter-modulation distortion (IMD). The IMD is that generated by one’s own power amplifier (PA), when operating over an adjacent band of frequencies, and arises as a result of the non-linear nature of the PA when engaged in the transmission of modulated multi-carrier (MMC) signals. The IMD appears in the form of inter-modulation products (IMPs), these occurring at multiple frequencies which may potentially coin cide with that of one’s own communication. The new version – which, like the original scheme, efficiently predicts the locations and strengths of the IMPs and, when coincident with the communication frequency (or frequencies), clears the IMPs from that frequency (or frequencies) – overcomes certain limitations of the original scheme. That is, it enables one to handle more sophisticated signal types whereby both bandwidths and powers of the signal com ponents may now be arbitrarily defined. Also, it extends the scheme’s applicability to multiple zones of distortion, this resulting in the need to handle 2nd-order and 4th-order IMD terms as well as the 3rd-order and 5th-order terms originally addressed.
