国家重点实验室 Main idea for channel polarization Channel coding problem trivial for two types of channels Perfect:C(W)=1 Useless:C(W)=0 Transform ordinary W into such extreme channels >Perfect channels:C(W)=1,the output Y determines the input X Useless channels:C(W)=0,the output Y is independent of the input X o Channel polarization is a technique to convert any binary-input channel into a mixture of binary-input extreme channelsMain idea for channel polarization  Perfect channels: C(W)=1, the output Y determines the input X  Useless channels: C(W)=0, the output Y is independent of the input X Channel polarization is a technique to convert any binary-input channel into a mixture of binary-input extreme channels 8