Patent ID: 7633851

Claim:
A circuit for generating a cyclic prefix of a symbol, in time domain, comprised of a sequence of samples in the time domain, said sequence of samples having a first number (N) samples beginning at a first (1 st ) sample and ending at a last (Nth) sample, a subset of the sequence of samples has a second number (N−n) of samples starting at an intermediate sample (n), each respective sample between the intermediate sample, and the last (Nth) sample, where n is greater than or equal to 1 and less than N, said prefix being a reproduction of the subset of the samples of the symbol at a beginning of the symbol, the symbol being obtained by inverse Fourier transform of complex coefficients corresponding to respective frequencies, the circuit comprising: means for shifting a respective phase of each complex coefficient by a value proportional to its frequency; means for generating the sequence of samples in time domain of the symbol via an inverse Fourier transform on phase shifted complex coefficients such that said last samples of the symbol are shifted at the beginning of the symbol according to a circular permutation and such that the symbol is delayed by an amount of time for generating said prefix; a memory for storing the subset of samples, wherein said memory stores only the subset of samples without storing any other sample of the symbol; and means for copying at the end of the symbol the stored samples.