Currently, Tokaido-Shinkansen, a high-speed train in Japan, provides the passengers with an IPv4 environment using a leaky coaxial cable (LCX) system. On the other hand, we have been developing an infrared (IR) communication system with a fast handover mechanism to provide Shinkansen with more than 1 Gbps bandwidth. This paper proposes collaboration of the IR system and the LCX system to realize a system that provides broadband (more than 1Gbps), fault tolerance and IPv6 support. The proposed system installs the IR system at the upstream of the LCX system to keep the modifications to the existing LCX system as small as possible. To realize the proposed system, we modify Network Mobility Basic Support Protocol. We implemented the proposed system on Linux and measured basic performance in our test network. The results show that the overhead is small enough.