Optimised circular convolutions stage for OS/OSB FBMC receivers

A device configured to perform a stage of circular convolutions in an Overlap-Save Filtered-Bank MultiCarrier (OS-FBMC) or Overlap-Save-Block FBMC (OSB-FBMC) receiver, the stage of circular convolutions performing P circular convolutions between subsets of input samples and frequency domain responses of frequency shifted versions of a prototype filter associated to a Filtered-Bank Multicarrier (FBMC) modulation having Cg coefficients, said input samples being designated as [X(0) . . . X(KMP−1)] with M a number of subcarriers, K an oversampling factor of the FBMC modulation applied to a FBMC signal received by the receiver and P an integer greater than one, wherein the stage of circular convolutions comprises:

• a first Finite Impulse Response (FIR) filter implemented in the form of a transposed direct filter having Cg taps numbered p=−Δ to p=Δ with Δ=(cg−1)/2, a multiplier coefficient of each tap p within the set of taps −Δ+1;
• 0 having an equal value to a corresponding multiplier coefficient of tap (−p), and taking as input a subset X0=[X(0), X(P), X(2P), . . . , X((KM−1)P)] of said input samples;
• at least one Finite Impulse Response (FIR) filter, each of said at least one FIR filter being implemented in the form of a transposed direct filter having at least Cg−1 taps numbered p=−Δ+1 to p=Δ with
• Δ
• =
• C
• g
• -
• 1
• 2
• ,
• a multiplier coefficient of each tap p within the set of taps −Δ+1;
• 0 having an equal absolute value to a corresponding multiplier coefficient of tap (1−p), and taking as input a subset or a combination of subsets of said input samples;
• the multiplier coefficients of the first FIR filter and of the at least one FIR filter being based on said frequency domain responses of frequency shifted versions of the prototype filter associated to the FBMC modulation.