- Easily Implementable UTW-OFDM to Suppress Out-of-band Emission -

The research group of Prof. Keiichi Mizutani and Prof. Hiroshi Harada at the Graduate School of Informatics, Kyoto University, Japan, has developed a new highly spectrum-efficient communication scheme and system, dubbed UTW-OFDM (Universal Time-domain Windowed OFDM), with low out-of-band emission in order to improve spectrum efficiency.

The 5th-generation mobile communication system (5G) that will be started from 2020 or later has been developed internationally toward more highly efficient and multipurpose communications such as very high-speed communications and low-speed high-density sensor communications. However, frequency resources suitable for mobile communications have become starved. Therefore, the development of the high spectrum-efficient system maintaining backward compatibility with the conventional 4G LTE system is an urgent matter. To suppress the out-of-band emission dramatically, the filtering process is a major factor in baseband. However, the complexity of the filtering process becomes very high.

In the proposed system, only time-domain windowing processing with low complexity is applied to the transmitter. The parameters of time-domain windowing coefficients, i.e. windowing function type and size, can be variable flexibly for multipurpose use with multi-requirement systems. Moreover, large window size is applied to reduce the out-of-band emission dramatically.

This time, the characteristics of transmission signals of the proposed UTW-OFDM with LTE parameters were experimentally evaluated by using signal generator and spectrum analyzer. Additionally, bit-error-rate characteristics of the proposed UTW-OFDM with LTE parameters including convolutional turbo coding technology were evaluated by computer simulations. As a result, it was shown that the proposed system can achieve a dramatic out-of-emission suppression performance (more than 30 dB improvement comparing with the conventional CP-OFDM of the LTE) and fulfill the physical layer requirement of LTE.

More detail information can be obtained at http://www.dco.cce.i.kyoto-u.ac.jp/en/PL/PL_2016_01.html