Nowadays, tunnels commonly exist along some road or railway lines. Tunnel is of long and narrow shape, and is enclosed by mountains which often obstruct network signals coming into it, so some parts inside the tunnel turn into blind spots. Hence, to fulfill the coverage for tunnels is key in realizing seamless network coverage and thereby increase operators’ integrated competence.

    There are various coverage methods to fulfill the tunnel coverage. For a short tunnel, it is advisable to erect high-powered outdoor repeaters at the mouth of it, and adopt high-gain directional panel antennas to fulfill the coverage. Or the coverage can also be realized by installing directional antennas inside the tunnel associated with RF distribution method; for a long tunnel, it is advisable to employ a leaky cable that has both transmitting and radiating functions to fulfill the coverage.