GENERATING A SPECTRALLY EFFICIENT ROOT RAISED COSINE PULSE

摘要

An improved multicarrier modulation system and method is introduced which has the advantages of both isotropic orthogonal transfer algorithm orthogonal frequency division multiplexing (IOTA OFDM) and scalable advanced modulation (SAM). The invention generates a spectrally efficient root raised cosine (RRC) pulse shape to increase spectral efficiency without losing excessive power efficiency. A filter is used to window (102) the RRC pulse (101) that is greater in length than a predetermined modified RRC pulse. The windowed RRC pulse is then truncated (103) and normalized (104) to produce a modified target size pulse (105) in time. The invention greatly improves a major problem of conventional OFDM namely ACI due to the use of a wide subchannel filter. This allows OFDM to meet even the strictest ACI requirements, which were not possible using conventional raised cosine windowing methods.