SFBC-based MIMO OFDM and MIMO CI-OFDM Systems in the Nonlinear and NBI Channel

In this paper, we study the MIMO (multiple input and multiple output) OFDM (orthogonal frequency division multiplexing) and MIMO CI (carrier interferometry)-OFDM system that are based on the SFBC coding. We evaluate and compare the performances of MIMO OFDM and MIMO CI-OFDM system. For CI-OFDM realization, digital implemented CI-OFDM structure is used in which CI code spreading operation and carrier allocation are separately processed by simple IFFT type operation. From the simulation results, it is shown that MIMO SFBC CI-OFDM reduces PAPR significantly compared with MIMO SFBC-OFDM system. The out-of band re-growth of signal spectrum in MIMO SFBC CI-OFDM system is much smaller than MIMO SFBC OFDM. In the NBI (narrow band interference) channel, MIMO SFBC CI-OFDM system achieves considerable BER improvement, compared with the MIMO SFBC-OFDM system in which error floor occurs in most of SNR range. So, it can be expected that MIMO SFBC CI-OFDM system is very useful for the high speed communication system in the nonlinear HPA and NBI channel