6.3.1 Basics Let be the carrier freq of the kth sub-channel and A/the space of adjacent subcarriers,where=0,1,...K-1.By selecting symbol interval,T'=1/Af, the subcarriers are orthogonal regardless of the initial phases,that is,. ∫sin(2mf1+4)sin(2πf1+)dh=0. where i≠j,0≤i,j<K. In this case,we refer the comm. system to as orthogonal freq-division multiplexing (OFDM)system.OFDM has highest spectral efficiency due to smallest△f UESTC-Digital transmission thro BLAWGN channels Prof李晓峰 5