1. Communication Protocol Engineering Lab. Relay-by-Smartphone: Realizing Multihop Device-to-Device Communications IEEE Communication Magazine April 2014 Hiroki Nishiyama, Masaya Ito, and Nei Kato 2015. 05.02 Kim Jong chan (kimjongchan@kw.ac.kr) Kwangwoon Univ. Communication Protocol Engineering Lab. 1/15

2. Communication Protocol Engineering Lab. Contents  Introduction  System design for multihop D2D communications  First ever experimental prototype of routing technology fusion  Field experiment  Future prospect  Conclusion 2/15

3. Communication Protocol Engineering Lab. Introduction  Multihop device-to-device communication is important in disaster -Physical damage to base stations and insufficient available power -Such as Great East Japan Earthquake and Tsunami on March, 2011 -The usage methods of D2D communications Emergency messages to be sent from disconnected areas Information sharing among disaster victims in evacuation centers  In a disaster area, while the shortage of a mobile terminal’s battery can be solved by using mobile solar cells, message delivery remains a critical issue. -The message transmission to a destination that is far away. -The capability of transmitting the messages to the outside network -Way to exchange information in the refuge area 3/15

4. Communication Protocol Engineering Lab. Introduction  Focus on the fusion of existing wireless communication technologies and routing message delivery technologies, including Mobile ad hoc networks (MANETs), delay/disruption-tolerant networks (DTNs) 4/15

5. Communication Protocol Engineering Lab. System design for multihop D2D communications  Multiple wireless access interfaces -In order to improve efficient of D2D communication systems, it is necessary to select the optimal wireless access interfaces depending on the environment. 5/15

6. Communication Protocol Engineering Lab. System design for multihop D2D communications  Fusion of routing technologies -Routing is a dominant technology in multihop wireless communications. -To enable message exchange between any two terminals regardless of the routing technologies adopted, integration of routing technologies is necessary. -Routing technologies MANET-type  Traditional routing technology working in the network layer DTN-type  Routing technology over the network layer -MANET-type and DTN-type show different levels of performance depending on the environment and situation of users. 6/15

7. Communication Protocol Engineering Lab. System design for multihop D2D communications  Interconnectivity -Incorporation into other kinds of networking technologies Satellite communication systems Unmanned aircraft systems(UASs) Movable and deployable resource units (MDRUs) -Filtering unnecessary messages at the gateway -Gateway location  Security -Exchanging message  Compatibility -Various Terminal 7/15

8. Communication Protocol Engineering Lab. First ever experimental prototype of routing technology fusion  Experimental prototype system consisting of 30 smartphones -MANET is suitable for an environment where the terminals are static and in a dense area. -DTN is more suitable for an environment where user terminals have high mobility and are mostly isolated. -Technique that switches the terminal’s communication mode between MANETs and DTNs -All of the prototype terminals perform Optimized Link State Routing (OLSR) 8/15

9. Communication Protocol Engineering Lab. First ever experimental prototype of routing technology fusion  The architecture of DTN over MANET 9/15

10. Communication Protocol Engineering Lab. First ever experimental prototype of routing technology fusion  Communication mode switching 10/15

11. Communication Protocol Engineering Lab. First ever experimental prototype of routing technology fusion  Application for experimental use 11/15

12. Communication Protocol Engineering Lab. Field experiment  Message relay in an urban area -Sendai City in February 2013 -20 people with prototype terminal, freely move around a certain anchor point -The distance between neighboring anchor points was within the range of 50–200 m. -Using Wi-Fi  Success in delivering the message on a route the total length of 2.5 Km  Interconnection with UAS -The benefits of the UAS Flight at high altitudes for long durations Communication over a broad area Assistance for ground-to-ground communications 12/15

13. Communication Protocol Engineering Lab. Field experiment 13/15

14. Communication Protocol Engineering Lab. Future prospect 14/15

15. Communication Protocol Engineering Lab. Conclusion  Given that natural disasters such as earthquakes, tsunamis, hurricanes, and so on may occur anywhere at any time and cause destruction to network infrastructures, readiness for various emergencies in the sense of instanta-neous recovery of communication functionality by using only users’ mobile devices is of great importance.  The most important feature of our newly developed system is that users can transmit messages by relaying the messages through other mobile terminals such as smartphones, laptops, and tablet PCs. 15/15