Abstract: A data communication device to provide can have stable communication quality. Data communication device according to the present disclosure includes a fitting surface and an outer surface opposite from the fitting surface. Data communication device also includes belt, buckle, a communication electrode, and a communication unit. Belt is joined to buckle. The communication electrode is formed at belt or buckle to be exposed at the fitting surface. The communication unit is electrically connected to the communication electrode. Buckle includes a buckle mechanism. Because of this structure, belt can be set to have a right length. Therefore, a reduced clearance can be achieved between the communication electrode and a human body when data communication device is put on.

Abstract: A wireless communication system includes a first node as a source node having a wireless communication function, a second node as a destination node having a wireless communication function, and one or more third nodes configured to relay wireless communication between the first node and the second node. While a communication path through which data is sent from the first node to the second node is not established, the first node and the one or more third nodes send data in broadcast. After determining a destination in at least a part of the communication path from the first node to the second node, a node out of the first node and the one or more third nodes which has the determined destination sends data to the determined destination in unicast.

Abstract: A wireless communication system includes a first node as a source node having a wireless communication function, a second node as a destination node having a wireless communication function, and one or more third nodes configured to relay wireless communication between the first node and the second node. While a communication path through which data is sent from the first node to the second node is not established, the first node and the one or more third nodes send data in broadcast. After determining a destination in at least a part of the communication path from the first node to the second node, a node out of the first node and the one or more third nodes which has the determined destination sends data to the determined destination in unicast.