Patent ID: 8687719

Claim:
An Orthogonal Frequency Division Multiplexing (OFDM) process for transmitting data using multiple carriers through a communication channel having a bandwidth W split in N subcarriers arranged in K chunks of M subcarriers each, with Nâˆ’KÃ—M subcarriers=2Ã—Ms being allocated to form at least a first guard band and a second guard band located at the left side and at the right side of said bandwidth, respectively, said process comprising: automatically and periodically shifting, for each OFDM symbol being transmitted, said chunks to left or right of the subcarriers allocated to each chunk in order to overlap said guard bands and increase spectral diversity in short-time transmissions; receiving a sequence of OFDM symbol N-length vector s=(s 1 . . . s N ) in the frequency domain; applying an inverse Discrete Fourier Transform (IDFT) in order to generate a vector x based on the following formula: x = F N , Î± H â¢ s = [ F N â¢ diag ( 1 , â…‡ â…ˆ â¢ â¢ Î± â¢ 1 N , â€¦ â¢ , â…‡ â…ˆÎ± â¢ â¢ N - 1 N ) ] H â¢ s where F N corresponds to the N-size Discrete Fast Transform (DFT) matrix with entries F m , n = â…‡ - 2 â¢ Ï€ â¢ â¢ â…ˆ â¢ nm N copying and multiplying the N L first symbols of x by e iÎ± in order to constitute a cyclic-prefix preventing inter-symbol interference; concatenating the said cyclic-prefix with the said vector x in order to form an extended vector: x ext =[e iÎ± x Nâˆ’NL+1 ,e iÎ± x Nâˆ’NL+2 , . . . ,e iÎ± x N ,x 1 , . . . ,x N ] T transmitting said extended vector through said communication channel.