pilot subcarrier in Fixed WiMAX ( 802.16 d )

[alqasim]

pilot subcarriers

It was mentioned in the standard that the pilot subcarriers are modulated by BPSK and the the remaining data subcarriers depend on SNR value .

My question : Is it possible that the amplitude for pilot subcarriers are less than data subcarriers ( when we capture it in spectrum analyzer ).

 

[kel8157]

802.16d preamble

Yes it is. For frequency selective fading, I believe pilot tones can be affected.

 

[alqasim]

calculating pilot location 802.16

i meant that in normal situation , is there any differance in the magnitude between data subcarrier and pilot subcarrier .

 

[rfsystem]

fixed wimax-data carrier

I did not check the standards but pilot amplitude increase is normal because the total power increase is small but the phase/frequency tracking loop operate less noisy and the overall performance is better. For rolling pilots the same applies to channel estimation. I think for WiMAX the carrier to carrier channel variation is not much because channel estimation within the preamble is interpolated instead of measured. But correct someone me, I am fading some details.