Performance improvement of OFDMA cellular system using code division multiplexing in satellite/terrestrial integrated mobile communication system

A satellite/terrestrial integrated mobile communication system (STICS) is a hybrid mobile communication system using a terrestrial and a satellite cellular systems. If both systems use the same frequency band, the satellite downlink exerts interference to the terrestrial mobile phones. In this paper, we clarify the deterioration of a bit error rate and a throughput performance of the downlink terrestrial cellular system utilizing a multiple-input multiple-output orthogonal frequency division multiple access (MIMO-OFDMA) in STICS by computer simulations. In addition, we propose the application of MIMO-OFDMA-code division multiplexing (CDM) in which the frequency-domain code spreading is applied for MIMO-OFDMA to improve the performance in STICS. Also, it is demonstrated that the sufficient carrier to interference ratio (CIR) of the mobile phone to the satellite signal is about 6 dB.