  Many real-world communication networks often have hybrid nature with both
fixed nodes and moving modes, such as the mobile phone networks mainly composed
of fixed base stations and mobile phones. In this paper, we discuss the
information transmission process on the hybrid networks with both fixed and
mobile nodes. The fixed nodes (base stations) are connected as a spatial
lattice on the plane forming the information-carrying backbone, while the
mobile nodes (users), which are the sources and destinations of information
packets, connect to their current nearest fixed nodes respectively to deliver
and receive information packets. We observe the phase transition of traffic
load in the hybrid network when the packet generation rate goes from below and
then above a critical value, which measures the network capacity of packets
delivery. We obtain the optimal speed of moving nodes leading to the maximum
network capacity. We further improve the network capacity by rewiring the fixed
nodes and by considering the current load of fixed nodes during packets
transmission. Our purpose is to optimize the network capacity of hybrid
networks from the perspective of network science, and provide some insights for
the construction of future communication infrastructures.
