1. A method performed by a vector processor for performing a convolution between an input signal and a filter impulse response, said method comprising: obtaining a vector comprised of at least N 1 +N 2 - 1 input samples; obtaining N 2 time shifted versions of said vector, wherein each time shifted version comprises N 1 samples; and performing a weighted sum of said time shifted versions of said vector by a vector of N 1 coefficients; and to producing an output vector comprising one output value for each of said weighted sums.