https://it.mathworks.com/help/dsp/ref/dsp.iirhalfbanddecimator-system-object.html
dsp.IIRHalfbandDecimator - Decimate by factor of two using polyphase IIR - MATLAB
The dsp.IIRHalfbandDecimator System object performs efficient polyphase decimation of the input signal by a factor of two.
dspdecimatefactor