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How to determin bit period?

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cambyzhu

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tb bit period

I am designing an ofdm UWB system, the signal has bandwidth 528 MHz, and IFFT 64, 48 for OFDM symbols, so can anyone teach me how should I design the bit period? and what element should I consider ?
 

BW=528 MHz
N_FFT=64
Ncarr=48


frequency spacing of OFDM subcarriers:
Δf=BW/N_FFT=8.25 MHz

in order to use OFDM , subchannels must be orthogonal , so :

Δf=1/Tu or Tu=1/Δf ,
where Tu is the useful period of an OFDM symbol (the symbol perion in each subchannel).

Now depending on the modulation scheme you use , the bit period can be determined . for example if you choose QPSK as the modulation scheme ,each symbol consists of 2 bits and Tb=Tu/2

in MQAM or MPSK each symbol consists of log2(M) bits and hence
Tb=Tu/log2(M)

and this is the formula for determining the bit period on an ideal OFDM system

Tb=NFFT/(BW×log2(M) )


correct me if i'm wrong


regards
 

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