# How to perform convolution using polyphase structure

I am trying to implement convolution using polyphase structure but, how to split input samples among different filter banks is my major doubt. Please explain the same with example?

• Why do you want to use polyphase? It's only useful for specific applications and the best implementation depends on which application it is – Hilmar Jan 17 '20 at 8:36
• @Hilmar it's for a real-time narrow band filter. Already implemented other efficient methods but, it's been decided polyphase would be the best bet. How do I convolve using polyphase structure?, I already have my filter coefficients separated. – Nagashree Jan 17 '20 at 9:42
• yeah, but the polyphase decomposition type you use depends on why you're doing a polyphase implementation, so: we're going in circles. Please tell us why you're doing this filter in polyphase. – Marcus Müller Jan 17 '20 at 10:03
• @MarcusMüller I am doing this filter in polyphase for parallel processing and to have a smaller buffer requirement. Mainly I want to achieve continuous filtering and not hold any input sample. – Nagashree Jan 17 '20 at 10:14
• ee.ic.ac.uk/hp/staff/dmb/courses/DSPDF/01200_Polyphase.pdf: this is the pdf I went through before starting my implementation. – Nagashree Jan 17 '20 at 10:21

x(1:2:end) = cos(2*pi*f*t(1:2:end));