To ensure unequal error protection to a plurality of different bits in a communication system.

A method to process bits in a bit stream includes: a step of rearranging a bit stream by embedding high priority bits in a low priority bit stream, wherein orders of bits of both the priorities are maintained in the rearranged bit stream, and the rearranged bit stream includes blocks of bits, and each block includes one or more high priority bits being adjacent to each other disposed left of corresponding one or more low priority bits; and a step of modulating the rearranged bit stream using a Gray encoding method to produce an encoded bit stream.