Walsh matrix
Walsh code, for separating the multiple users on the same channel. These are based on a Walsh matrix, which is a square matrix with binary elements, and dimensions which are a power of two. It is generated from the basis that Walsh(1) = W1 = 0 and that:
Where Wn is the Walsh matrix of dimension n. For example:
Walsh codes are orthogonal, which means that the dot product of any two rows is zero.
This is due to the fact that for any two rows exactly half the number of bits match and half
Each row of a Walsh matrix can be used as the PN code of a user in a CDMA system.
By doing this the signals from each user is orthogonal to every other user, resulting in no
interference between the signals. If the Walsh code used by one user is shifted in time by more then about 1/10 of chip period, with respect to all the other Walsh codes, it looses its orthogonal nature This results in inter-user interference.