ence training sequence symbol symbol symbol SIGNAL DATA 1 DATA 2 Preamble Figure 3.5. Structure of the preamble and OFDM symbols Parameters Duration TFFT FFT or IFFT period 3.2 us (1/AF) TGI Duration of guard interval GI 0.8 us (TFFT/4) TGI2 Duration of guard interval GI2 1.6 us (TFFT/2) TSHORT Duration of short training symbol 8 us (10x TFFT/4) TLONG Duration of long training symbol 8 us (TG12+2xTFFT) TPREAMBLE Preamble duration 16 us (TSHORT + TLONG) TSIGNAL Duration of SIGNAL symbol 4 us (TGH+FFT) TSYM Duration of DATA symbol 4 us (TGI+TFFT) Table 3.3. Values of the duration of the different parameters A short training symbol consists of 12 sub-carriers, which are modulated by the elements of the sequence S: S-26,26 = ((13/6) X 0, 1+j, 0, 0, 0, -1-j, 0, 0, 0, 1+j, 0, 0, 0, -1-j, 0, 0,0, -1-j, 0, 0, 0, 1+j, 0, 0, 0, 0,0, 0, 0, -1-j, 0, 0, 0, -1-j, 0, 0, 0, 1+j, 0, 0, 0, 1+j, 0, 0, 0, 1+j, 0, 0, 0, 1+j, 0,0} 56 Wi-Fi Integration to the 4G Mobile Network A long training symbol consists of 53 sub-carriers, including the value 0 at central frequency, which are modulated by the elements of the sequence L: L-26,26 = {1, 1, -1, -1, 1, 1, -1, 1, -1, 1, 1, 1, 1, 1, 1, -1, -1, 1, 1, 1, 1, , -1, 1, 1, 1, 1, 0, 1, -1, -1, 1, 1, -1, 1, -1, 1, -1, -1, -1, -1, -1, 1, 1, -1, -1, 1, -1, 1, -1, 1, 1, 1, 1} 3.1.2.7. OFDM multiplexing The complex numbers are numbered from 0 to 47 and are subsequently mapped onto OFDM sub-carriers numbered -26 to -22, -20 to -8, -6 to -1, 1 to 6, 8 to 20 and 22 to 26. Sub-carriers -21, -7, 7 and 21 are ignored and subsequently used for the insertion of pilot sub-carriers. The sub-carrier 0, associated with the central frequency, is omitted and filled with the value 0. Parameters Values NSD (number of sub-carriers assigned to the DATA field) NSP (number of sub-carriers assigned to pilots) NST (total number of sub-carriers) 0.3125 MHz AF (spacing between sub-carriers) (20 MHz/64) Table 3.4. Parameters of OFDM multiplexing 3.1.2.8. Frequency plan The 802. 11a interface operates in the 5 GHz U-NII (Unl