Communication device, communication system, and communication method

A communication system comprising:

• a plurality of node devices and a gateway device that perform communication via a wireless ad hoc network, wherein
• the gateway device includes
• a packet receiving unit that receives, via the wireless ad hoc network, a packet transmitted from a node device,
• a congestion detection unit that detects, based on the packet received by the packet receiving unit, that congestion occurs in a communication path along which the packet reaches the packet receiving unit,
• a congestion control message generating unit that generates, when the congestion detection unit detects that the congestion occurs in the communication path, a congestion control message that instructs to take an action to avoid the congestion in the communication path, and
• a message transmitting unit that transmits the congestion control message generated by the congestion control message generating unit to the node device, and
• each of the node devices includes
• a message receiving unit that receives the transmitted congestion control message,
• a congestion avoidance action control unit that takes the action to avoid the congestion in the communication path when the message receiving unit receives the congestion control message, and
• a message retransmitting unit that retransmits the congestion control message received by the message receiving unit.

A computer readable storage medium having stored therein a communication program causing a computer to execute a process comprising:

• receiving, via a wireless ad hoc network, a packet transmitted from a node device;
• detecting, based on the packet received at the receiving, that congestion occurs in a communication path along which the packet is transferred;
• generating, when it is detected that the congestion occurs in the communication path at the detecting, a congestion control message that instructs to take an action to avoid the congestion in the communication path;
• and
• transmitting the congestion control message generated at the generating to the node device.