On heterogeneous mobile network connectivity: Number of gateway nodes

A mobile tactical network is characterized by wireless communication nodes operating over a disperse geographical area. As tactical nodes move during an operation, the network may partition into several segregated clusters. Once the network has partitioned, mobile nodes in different clusters cannot maintain connectivity due to insufficient radio transmission range. The partitioned network will have limited capability in providing seamless communication services to sensors and combat systems. To mitigate this problem, a subset of the mobile nodes can be collocated with and connected to a more powerful communication node to form a gateway node. These more powerful nodes have longer radio transmission range and are assumed to be connected with each other to form an upper tier network (e.g., satellite network). To reach its destination mobile node through nodes in the upper tier network, a regular mobile node can first connect to a gateway node. The gateway node can then forward traffic through the connected upper tier network to another gateway node. In this scenario, communication between mobile nodes in different clusters can only occur when each cluster contains a gateway node. In this paper, we investigated the number of gateway nodes needed in order to maintain certain level of connectivity in a mobile network. Given the node density of the mobile network, we quantified the relationship between network connectivity and the number of gateway nodes. In a densely populated mobile network, we found that only a small number of gateway nodes are needed to achieve good network connectivity. Moreover, as the node density increases, the percentage of gateway nodes can decrease at a larger rate than the node density increase rate while still achieving a good network connectivity.