OFDM Schemes with Non - Overlapping

| 1 For Orthogonal Frequency Division Multiplex-ing (OFDM) schemes, the time waveform plays a major role not only in shaping the spectrum of the transmitted signal but also in separating the signal subcarriers at the receiver. The selection of such waveform is then very important and can make a big diierence in spectrum utilization and system performance. The diiculty in using pulse shaping with OFDM appears in the detector design since smooth time waveforms destroy the orthogonality between subcarriers and introduce Inter-Channel Interference (ICI). This paper investigates the use of non-overlapping signal waveforms for OFDM schemes. It is shown that pulse shaping for such schemes can be equivalently achieved using a discrete shaping matrix. Such shaping structure is very suitable for digital implementation and can be combined with OFDM schemes without aaecting their IDFT/DFT operators. It therefore makes the use of guard time interval (cyclic preex) for OFDM schemes possible with any kind of non-overlapping shaping waveform.