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use of radio wave resources in the factory. Figure 8 shows an overview of the conguration of its protocol stack.To maintain compatibility with existing applications, the functions are arranged separately in the higher-level and lower-level layer of TCP/IP. e following criteria are also generally understood to constitute an important factor for decision making: ability to sustain stable operation as a whole system and safety of mutual connection (authen-tication, security).5Toward realization of smart factories with the full advantage of wireless communicationis report described the challenges that lay ahead in the passage toward full-edged utilization of wireless com-munication technologies in the factory. Based on the results from demonstrative on-site experiments, this report stressed the importance to understand the nature of the communication needs and to select accordingly an opti-mum communication system that should be determined in consideration of two factors: the environment in which the machinery to be controlled is located, and the functions to be realized by them. To clarify the current situation of the factory, the author identied parameters that characterized various situations in the factory, and used these parameters to dene four development stages of wireless communica-tion usage. In line with these denitions, the author is planning to continue research and development of an SRF wireless communication platform and decision support technology, which will help enable even non-specialists in this area to design manufacturing equipment.Acknowledgmentse author expresses deep gratitude and appreciation to OMRON Corporation, Advanced Telecommunications Research Institute International (ATR), NEC Corporation, NEC Communication Systems Ltd, Fujitsu Kansai-chubu Net-tech Ltd, and Sanritz Automation Co., Ltd. for their cooperation in our project, and the engineers of their factories who kindly arranged the venue for our demon-strative experiments.ReferenceR1“Situation and Problems in manufacturing fields,” http://www.meti.go.jp/com-mittee/sankoushin/seizou/pdf/001_02_02.pdf (in Japanese)2S. Itaya, et al., ”Experiments of Wireless Communications in the Manufacturing Field —Towards Flexible Factory—,” IEICE Technical Report, RCS2015-156, pp.1–6. (in Japanese)3J. Hasegawa, et. al., “Experiments of Wireless Communications in the Manufacturing Field —Evaluation of Communication Quality using 920Mhz band—,” IEICE Technical Report, RCS2015-157, pp.7–12. (in Japanes)4A. Amagai, et al., ”Experiments of Wireless Communications in the Manufacturing Field — Measuring the Jitter and Burst Loss—,” IEICE Technical Report, ASN2015-85, pp.33–38. (in Japanese)5S. Itaya, et al., “Experiments of Wireless communications in the Manufacturing Field - A Discussion about Environment and Communication Quality-,” IEICE Technical Report, RCS2015-86, pp.1–6. (in Japanese)6J. Hasegawa, et. al., “Experiments of Wireless Communications in the Manufacturing Field —Relationship between Hygro-thermal Environment and Communication Performance—,” IEICE Technical Report, RCC2015-87, pp.7–12. (in Japanese)7S. Itaya, et al., “Multiple-band Wireless Communications in the Manufacturing Field —Manufacturing Field as a System—,” IEICE Technical Report, CCS2015-75, pp.45–50. (in Japanese)8Flexible Factory Project, http://www.nict.go.jp/en/press/2017/03/01-1.html9RMR9000 ThinkTube, http://www.thinktube.com/products/rmr900010Wi-SUN Alliance, http://www.wi-sun.org/Satoko ITAYA, Ph.D.Senior Researcher, Wireless Systems Laboratory, Wireless Networks Research CenterIndustrial wireless communication, Ad-hoc network, Sensor network2 Terrestrial Communication Technology Research and Development42　　　Journal of the National Institute of Information and Communications Technology Vol. 64 No. 2 (2017)