ICNPAA 2010: Mathematical Problems in
Engineering, Aerospace and Sciences

CDMA radio to station links are asynchronous and thus user signals are not absolutely orthogonal though interference is low. Separation from a cell to another requires a long code that with a period different of the symbol. Due to residual interference issues if all user operates at full power the number of possible user is reduced, so good capacity is assured by fast control of individual user transmission levels, independently of what error correcting code is used. In satellite systems the transmission delay avoids a fast control, and its necessary to use another scheme to enhance traffic capacity. Except for Globalstar, that remain close to IS95 standard, all the other systems made option to long pseudo random codes and Gold codes to separate users. Here is described a diversity scheme that use the fact that slipping the long code and keeping matched the Gold codes of copies of messages of a radio, they are nearly orthogonal one to each other, and its annoying effect in other user per unit of energy is unchanged. This channeling expansion allows diversity to be used, reducing the average power per user and enhancing capacity.