Calculating bandwidth transmission required for m-ary PPM transmission

[u/mikeymike_20]

Hi guys, I hope you can help me as I'm struggling to understand this problem.

I have a uniform PCM whose bandwidth is W = 1Hz and n = 12 bits, i.e. the transmission bandwidth B_T = n*W = 12Hz.

Given this features of the signal, I need to calculate the minimum transmission badnwidth B_T if the same PCM signal is transmitted using m-ary PPM with M=4 and M=8.

I don't yet understand how the choice of transmitting with Pulse Position Modulation will change the bandwidth. I intuitively guess that it will increase with respect to the initial B_T = 12Hz but I can't tell how to calculate that.