Implementation and Experimental Results of Rotational OFDM Transmission: Rotational OFDM Performance with Turbo Decoder

This paper presents the experimental results of rotational orthogonal frequency division multiplexing (R-OFDM) performance with a turbo decoder implemented in an IMT-Advanced testbed. Taking into account recent advances in research and development toward realization of the IMT-Advanced system era, the authors are developing the testbed. The R-OFDM is multi-carrier transmission scheme and previously proposed by the authors. Its feature is to use rotational code division multiplexing that enables OFDM to obtain suitable frequency diversity gain. However, the previous work is only predicated on computer simulation. In this paper, the R-OFDM is implemented on the testbed and experimentally evaluated by distorting the R-OFDM signal on radio wave with a fading simulator. When packet error rate is measured, it is verified that measurement results are in good agreement with simulation results. The measured deterioration of required carrier-to-interference power ratio (CIR) is suppressed by about 0.5 dB compared with the simulation. The experimental results also demonstrate that the R-OFDM can reduce the required CIR of OFDM even without T2 decoder by about 1.1 dB.