256-QAM

• See QAM (Quadrature Amplitude Modulation)
• The 256-QAM is a specific case of M-ary QAM scheme in which a carrier wave of fixed frequency can exist in one of 256 different states in the constellation plot.
• Each symbol consists of 8 bits out of 256 different possible combinations ranging from 00000000 to 11111111.
• Thus, the total number of bits that can be accomodated in a symbol for 64-QAM is 6.
• Since, this scheme uses binary data to perform modulation and demodulation, the number of combinations possible with eight bits is 28 i.e. 256.
• Or equivalently, the number of bits that can be accomodated as per equation 2 is log2 256 = 8.