An Initial Acquisition Scheme Combined with Carrier Recovery for Modified Walsh-Hadamard Code Division Multiplexing

Walsh-Hadamard code division multiplexing (WHCDM) is suitable for helicopter satellite communications as it has robustness against a periodic channel blockage due to rotor blades. Modified WHCDM (MWHCDM) enhances robustness and achieves excellent bit error rate performance. However, the initial acquisition performance of MWHCDM is inferior to that of WHCDM, which has less robustness. To solve this problem, we propose a novel initial acquisition scheme for MWHCDM in this paper. The proposed scheme is combined with a carrier recovery method for MWHCDM to improve acquisition performance. Additionally, it employs a novel evaluation function. The computer simulation confirms the proposed scheme remarkably improves the initial acquisition performance.