An OFDM spread spectrum system using lapped transforms and partial band interference suppression

A system that uses orthogonal frequency division multiplexing (OFDM) as a spread spectrum modulation is introduced and its performance is evaluated in the presence of tone interference. Interference excision, in which some of the transform bins are removed in the detection process, is used in the receiver. The BER performance obtained using a number of block transforms is compared to that obtained using the modulated lapped transform (MLT) and it is shown that the MLT provides much better performance due to its ability to confine the interference energy to a few transform bins.