Time-switched space-time coded OFDM over time-varying channels

In this paper, we propose a time-switched space-time coded orthogonal frequency division multiplexing scheme over time-varying channels. The base station can use the proposed TSST-OFDM scheme with only two power amplifiers for four transmit antennas. For a given space-time code, we show that the signal to inter-antenna interference ratio is a function of Doppler frequency in time-varying channels. The proposed scheme not only gets time-switched diversity and lower decoding complexity, but also less sensitive to the time-varying channels, hence it exhibits better performance than quasi-orthogonal space-time coded scheme.