6.3.1 Basics If the channel is not flat,an alternate approach to avoid ISI is to subdivide the channel into a number of narrow sub-channels,which are nearly flat. And the data is transmitted in a multicarrier or FDM manner. x(r)K sub-channels (1)=Cx (1)+n (t) Bit stream Bit stream C=C S2P P2S C UESTC-Digital transmission thro BLAWGN channels Prof李晓峰 3