Orthogonal Code Generation

In order for CDMA to work correctly, a code for one signal must be orthogonal to all other codes being used. Many algorithms exist to produce sets of orthogonal codes, and the Walsh set is one such example.

To generate a Walsh set of orthogonal codes, a matrix H1 = [ 0 ] must first be defined. Then, the next iterations are as depicted in the figure below.

Each row in the matrix represents a code for a particular signal. To keep the mathematics simple, the binary system is mapped to polar, so 0 becomes -1.