Hi Experts.
Why PUCCH coverage in the cell improves by around ~3 dB using long formats as compared to short formats?
It’s because of pi/2 BPSK modulation used.
Pi/2 BPSK is a lower order modulation which reduces the SINR requirement for correct symbol detection.
It also has a lower PAPR which helps the UE to operate more efficiently and with a higher average power.
Any other advantages of using pi/2 BPSK at Uplink?
I mean, what are the special properties of pi/2 BPSK?
That’s understood the benefit of pi/2 bpsk, but with long PUCCH if we use qpsk_4psk or pi/2 bpsk coverage will be higher with long pucch then short pucch.
So, asked, what can be the reason of difference in coverage?
So UE can operate with higher power, so uplink coverage range improved.
It means with long PUCCH cell edge UE can be benefited.
Virtually cell range increased in Uplink.
I am saying is it not necessary to use pi/2 bpsk modulation only with long pucch, or is it?
Yes, without pi/2 also, because long PUCCH has 4-14 symbols so PUCCH is spreaded over time domain.
Less prone to interference.
It requires lesser freq domain resources so better power per subcarrier.
So better stable coverage but have longer feedback latency.
So not useful where delay budget requirement is less.
There only short pucch to be used.
Also format 3/4 uses DFT-S-OFDM modulation where transform precoding used & with pi/2 lower modulation order can be used which helps very low SNR transmission in a large cell.
