# How to specify the input data bit width for fixed point implementation in windowed OFDM?

I am implementing a fixed point model of Windowed OFDM and to quantize the input data, I used 16 bits(complex) to encode it. But I am not sure how do we specify the minimum number of bits that should be used to encode the input ensuring the output wont be "off" from the expected results.

I saw a similar question in Bit width for FFT but the person has said assuming "M" input bits. Is it an empirical data that you set by trial and error or is there some maths behind it.

Thank you

• Example - If the EVM spec says minimum 1% , your fractional resolution should which can be achieved with at least 7 fractional bits ($\frac{1}{2^7}$). You cannot use 6 bits because resolution is 1/64=0.015625. So check if there are some restrictions like these in your case. – jithin Mar 30 '20 at 9:41