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collection network” where the power supply is especially not limited and which is characterized by mesh topology with many radios; 2. “Ultra-low-energy operation network” which is characterized by low power consumption assum-ing the time of battery driving, etc.; and 3. “Reinforced mesh network” which assumes service development in the environment, such as a devastated district and plants, where the application of radio communication links has not been assumed in the past. is paper especially as-sumes the high capacity data in item 1 and describes the research and development concerning the eective routing technology on said form.2Layer 2 Routing control study2.1Principle of Layer 2 Routing controle greatest characteristic of the routing control tech-nology in this study is to control the action of the informa-tion exchange between terminals and so on by using the control by MAC layer known as Layer 2 in the Personal Area Network[5]. erefore, the information to be handled is described by IE (information element), an information unit handled by the MAC layer, and is exchanged and handled by the function of the MAC layer. It is believed that this reduces the redundancy compared to the conven-tional routing control handled by IP (internet protocol), as Layer 3, and simple handling becomes possible[6]–[8].We describe the main technologies of the Layer 2 Routing (L2R) control for which we implemented research and development and a demonstration from the next subsection.2.2Autonomous mesh topology constructionis function allows each radio device, which com-poses a mesh structure, to sense the whole mesh structure by regularly sending out a mesh topology construction signal including one’s own information — connecting to other radios and so on — and by receiving the same signal from other radios. e radio which sends out the rst mesh topology construction signal is called the mesh route, and signals from other devices are composed on the basis of those from the mesh route.Figure 2 shows an operating example of the mesh topol-ogy construction signal exchanges in the mesh by mesh root R. In Figure 2 (i), the mesh root R which attempts to construct a mesh sends out the rst mesh-topology con-struction signals including the information of R, and de-vices A and B receive the signals. is allows A and B to detect the presence of a mesh and the presence of R adja-cent to them at the same time. Furthermore, they can as-certain the communication quality between R and them based on the received mesh-building signal.Next, A and B send out the mesh topology construction signals with an aim to provide the same information to other devices including R (refer to Fig. 2 (ii)). Devices C and D which receive the signals implement the same procedure (refer to Fig. 2 (iii)). Eventually, ve devices, R, A, B, C, and D, build a mesh, ascertain adjacent devices, reachable devices and the communication quality between them, and can establish the proper relay path with a special radio as a destination, as shown in Fig. 2 (iv).2.3Data concatenationis function reduces the number of data frames by combining multiple data frames addressed to the same destination and by relaying them as one data frame to a next device, and prevents performance degradation of data collection by the reduction of bottleneck blockage and FiF2　 Autonomous mesh topology construction2 Terrestrial Communication Technology Research and Development32　　　Journal of the National Institute of Information and Communications Technology Vol. 64 No. 2 (2017)