An Initial Acquisition Scheme with Reduced Complexity for Modified Walsh-Hadamard Code Division Multiplexing

Modified Walsh-Hadamard code division multiplexing (MWHCDM) has an anti-blockage capability. It is thus suitable for helicopter satellite communications where the transmission channel is described as the periodic blockage channel. This paper addresses the computational complexity reduction of the initial acquisition for MWHCDM. The conventional initial acquisition scheme employs the sliding Walsh-Hadamard transform (WHT). A narrowing function based on the redundancy of MWHCDM signals is proposed to reduce the sliding WHT. Computer simulation shows that the proposed narrowing function reduces the sliding WHT by about 70% without acquisition performance degradation.