A novel AFC scheme for Walsh-Hadamard code division multiplexing

In this paper, we propose a novel automatic frequency control (AFC) scheme for code division multiplexing (CDM) system employing Walsh code. The proposed AFC scheme discriminates the frequency shift of the received signal by detecting the signal energy after Walsh-Hadamard transform (WHT). The configuration of the proposed AFC scheme is analogous with that of delay locked loop (DLL) for direct-sequence spread-spectrum (DS-SS) communications. The initial acquisition performance of the proposed AFC scheme is evaluated by computer simulation. It is confirmed that the proposed AFC scheme achieves fast acquisition when the multiplexing factor is less than WHT order.