Permutation spreading in wavelet OFDM systems

In this paper the use of permutations as a mean of spreading the spectrum of the frequency channels in a general multicarrier modulation scheme is presented. Our first objective is to demonstrate how signature waveforms suitable for multiple access communications can be generated by applying permutation transformations to orthogonal channels generated with filterbanks or DFT techniques. The second objective is to motivate the use of such techniques as a mean of achieving immunity to timing errors, which can cause severe Adjacent Channel Interference (ACI) in multicarrier systems, due to large spectral overlap among adjacent channels. An efficient implementation of the interleaver implementing the considered permutations is also described.