The Bias Routing Tree Avoiding Technique for Hierarchical Routing Protocol over 6LoWPAN

6LoWPAN is a low-power wireless personal area network and a technique to apply TCP/IP stack to sensor networks. By installing IPv6 stack to the sensor node, the sensor networks have interoperability with the external IPv6 network. To solve the 6LoWPAN's restrictions, IETF working group recently published problems, IPv6 header compression, and routing mechanism requirement documents through their study. Among the suggested routing mechanisms, there is a hierarchical routing protocol designed to establish a hierarchical tree with parent and child nodes to transmit packets. However, the authors design only the address allocation mechanism and the routing mechanism. In our paper, we describe one of the hierarchical routing protocol's problems and suggest a mechanism to avoid the bias routing tree that could happen in the condition child nodes don't attach to parents nodes evenly. The simulation result shows that the four nodes are suitable for communication.