where 0 < m < M and 0 < n < N , and denotes the complex conjugate operator. Fig. 4 shows the elements relationship
in order to have a real-valued IFFT for T matrix. In this configuration, only regions 1 and 2 are used for data transmission
independently, and regions 3 and 4 are calculated accordingly to have a real-valued IFFT. Moreover, the symmetry requirements for elements that have been deliberately set to zero would be automatically satisfied.
Constellation Mapping: The input data is decomposed into 2-bit symbols. Each symbol is converted to a complex phase by
the following rules: