B. Bottleneck Node
Under assumption (4), collisions occur frequently in the center of the network.
Therefore, the number of transmission frames is limited in the center of the network.
The number of nodes in the string multi-hop network is defined as N.
Then, the bottleneck node of the network, n
In order to obtain the maximum throughput, the present analysis need only consider the maximum throughput of the bottleneck nodes, which is similar to the cases in [4]-[6].