2009 Volume E92.A Issue 9 Pages 2209-2217
Aiming at actual evaluation of IMT-Advanced system performance using field tests, this paper develops an IMT-Advanced testbed system with a transmission bandwidth of 100MHz. Taking into account recent advances in research and development of an IMT-Advanced system, orthogonal frequency division multiplexing (OFDM) with multiple-input multiple-output (MIMO) are also promising technologies in IMT-Advanced. In addition, in order to meet the requirements for IMT-Advanced, the system seems to have a bandwidth of about 100MHz with the aid of MIMO transmission. The developed system is based on the above more reliable prediction compared with previous studies, and the goals of this development are to provide a more realistic transmission performance, judgment criteria for operators introducing new air interfaces, and to explore new applications. This paper also presents the experimental results of rotational OFDM (R-OFDM) and twin turbo (T2) decoder implemented in the testbed and demonstrates that our proposals are better than the conventional schemes in actual radio transmission. Both physical layer technologies have been proposed by the authors, however, the previous works are only predicated on computer simulation. In this paper, the proposals are experimentally evaluated by distorting the transmitted signal on radio waves with a fading simulator and additional noise generator. When the packet error rate performance is measured, the measurement results are verified to be in good agreement with the simulation results. The experimental results also demonstrate that the R-OFDM can reduce the required carrier to the interference power ratio (CIR) of OFDM by about 1.1dB in single-input single output (SISO) multi-path fading channel. In addition, it becomes clear that the T2 decoder is better than the turbo decoder in error correction, and the required CIR reduction achieves about 0.8dB in SISO AWGN channel. The throughput performances are also measured with different modulation and coding conditions, and the measured forward throughput in the SISO AWGN channel achieves up to 373.6Mbps. In addition, by use of 2×2 MIMO transmission, the measurements results substantiate that throughput of 512.7Mbps can be realized even in the multi-path fading condition.