Fundamental study of ad hoc network routing protocols

　The growing trend of mobile phone in the recent years is quite impressive. One of the reasons for such growing is that the mobile phone functionally is not only limited to phone call, it also acts as a mobile node that supports data communication, such as i-mode or email. In addition, mobile phone is expected to be equipped with short-range communication function (Bluetooth, wireless LAN, etc) and act as a complex mobile node in the near future. As such, an ad hoc network where each mobile node can be used as a relay node without any assistance from the base station to mutually communicate with each other has attracted many attentions.

• With only mobile node, anytime and anywhere a network can be organized.
• Mobile node can join and leave the network on the fly.
• Each mobile node can relay packet to others.
• The network topology changes frequently because of the node’s mobility.

　To accommodate the above characteristics, it is necessary for a decentralized control scheme rather than to assume a centralized control station. It is important for an ad hoc routing protocol to consider the following issues:

• Route discovery.
• Route recovery when encounter a route failure.
• Effective use of wireless bandwidth.
• Power consumptions of the mobile node.

　Currently, Watanabe Laboratory studies the following research topics, ad hoc routing protocol utilizing location information from GPS and quick route recovery by utilizing multiple routes.