1. 1) M. Pätzold, 5G Sets Around the Globe, IEEE Veh. Technol. Mag., 14 (2019), 5-11.
2. 2) K. Umeno, On Complex Spreading Sequence with Constant Power and Exact Orthogonality for Chaos-CDMA : Integration of OFDM and CDMA via Chaos-CDMA, IEICE Technical Report, NLP2008-37 (2008), 23-27.
3. 3) K. Umeno, Spread Spectrum Communications Based on Almost Periodic Functions : Almost Periodic Code Approach versus Chaotic Code Approach for Communications, IEICE Technical Report, NLP2014-62 (2014), 87-90.
4. 4) I. Nakazawa and K. Umeno, Almost periodicity frequency arrangement and application to satellite communication system (in Japanese), IEICE Technical Report, CCS2015-33 (2015), 23-26.
5. 5) I. Nakazawa and K. Umeno, Performance Evaluation of Wideband Radio Communication Systems using Almost Periodic Frequency Arrangement, in: Proc. of ICSGTEIS 2016, pp. 673-678, Bali, Oct., 2016.