STFBC method for the ICI reduction in OFDM communication system

In OFDM communication system suitable for the highspeed broadband transmission, ICI (intersubcarrier-interference) caused by phase noise and frequency offset results in poor system performance. In this paper, new STFBC (space time frequency block coding) method combining ICI self-cancellation scheme and antenna, time, frequency diversity is studied to reduce ICI effectively. CPE (common phase error) and ICI are analyzed by the phase noise linear approximation method in the 4 kinds of systems. CIR (carrier-to-interference ratio), PAPR (peak to average power ratio), PICR (peak interference to carrier ratio), BER (bit error rate) and bandwidth efficiency are discussed to analyze the system performance degraded by phase noise of the PLL (or frequency offset) in the 5 kinds of systems. The SCI (self-channel interference) that usually happens in the STBC (space-time block coding) method can be easily avoided in above STFBC method. STFBC method considerably reduces ICI and SCI. Conclusively the proposed STFBC method using diversity technique can show excellent performance without the loss of bandwidth efficiency, compared with the other conventional methods, although it lowers the transmission speed.