Complex Complementary Sequence Real Orthogonal Spreading OFDM Scheme for HF Communication Link

The complementary M-ary orthogonal spreading with frequency division multiplexing (CMOS-OFDM) is an efficient scheme for providing high bit error rate (BER) performance and low peak to mean envelop power ratio (PMEPR) in (HF) communications system. In the CMOS-OFDM, OFDM implemented based on sequence pairs where there issue that one data symbol transmitted through two symbols. this paper, we present using complex sequences which satisfy real domain orthogonality. (CROS-OFDM) restrict PMEPR 3dB provides times of CMOS-OFDM. CROS-OFDM uses zero-center like CMOS-OFDM hence it suitable HF Wi-Fi system direct current subcarrier not used. simulation results show higher BER performance.