Performance of CDMA system using analog PN sequences produced by code-orthogonalizing filter

This paper proposes a novel asynchronous direct sequence/code division multiple access (DS/CDMA) communication system using analog PN sequences that have an orthogonal relation for all users due to the code-orthogonalizing filter (COF). In the base station receiver, the tap coefficients of the COF can be adaptively controlled "to orthogonalize" or "to approach to orthogonalize" to various received PN sequences. When the analog PN sequence arranged tap coefficients of the COF is assigned to a transmitter of each mobile user in order, multiple access interference (MAI) from mobile users (up-link) can be reduced considerably. The principle of the COF and the proposed system are described. By computer simulations, the bit error rate (BER) properties, convergence decision method and amplitude limiter for the analog PN sequence design are examined in an AWGN environment.