Tatsuya Kikuzuki

Automatic Standard Classification Method for the 2.4 GHz ISM Band

As IoT (Internet of Things) systems using wireless standards sharing the 2.4 GHz ISM band become widespread, radio interference often disturbs data communication. In order to mitigate interference-related problems, it would be helpful to have a method that determines to which standard a received packet belongs. However, conventional methods do not analyze the actual environment of congestion nor do they classify narrowband signals. In this paper, we propose identification algorithms and an automatic standard classification method that identifies WLAN/IEEE 802.15.4/BT (Bluetooth)/BLE (Bluetooth Low Energy), which are considered typical standards in the 2.4 GHz ISM band. The results show that the identification algorithms improve detection sensitivities compared to conventional ones, and the proposed method of automatic standard classification accurately analyzed the actual situation where radio waves of plural standards overlap one another.

Realizing safe and reliable vital sings monitoring with wireless body area networks

In this paper, we report development and performance verification of a wireless body area network prototype compliant with the MAC protocol of the IEEE802.15.6 BAN. The relaying functionality which utilizes a relay between a hub and a node is confirmed when a direct path between them is not available due to shadowing effects. The delay due to switching to the relay topology is less than one second. Also, ID-based frequency channel hopping mechanism is introduced and verified to be able to quickly avoid frequency channel interference among BANs. In addition to that, transmission power control with body movement detection is employed to reduce sporadic disconnection through giving an extra amount of transmission power when the node detects a large fluctuation in received power. With functionalities mentioned above, the prototype is expected to be used for medical monitoring applications where requirements for data delay and disconnection are rather severe.