Large buildings such as shopping malls, entertainment centers and hospitals often cannot be fully covered by outdoor base stations because of their large size and complex internal layout. Reliable signal coverage therefore needs to be provided by constructing MDAS indoor antenna distribution systems inside the building.

The MDAS multi-mode digital optical fiber distribution system is an ideal solution for large-scale indoor coverage. An MDAS system typically consists of three components: a main unit (MU), expansion units (EUs) and remote units (RUs). The MU connects to the base station / RRU RF output, converts the RF signals into digital optical signals and distributes them over four fiber links to up to four EUs. Each EU then transmits the digital optical signal over eight fiber links to eight RUs. Each RU converts the digital signal back to RF, amplifies it and feeds the connected antennas to provide coverage.

Small-Building Indoor Coverage

For small households where the indoor mobile signal is weak—typically in areas with complex layouts, far from windows or in basements—while the outdoor signal is still good, a simple indoor coverage solution can be deployed. A 5D-FB coaxial cable is used to connect the donor (receiving) antenna to the signal booster unit. An omnidirectional ceiling antenna is installed roughly every 100 m² indoors to provide uniform coverage. At the output port of the signal booster, a 5D-FB coaxial cable connects to a power divider or coupler, distributing the amplified signal to each coverage antenna.

High Rise Building Solution

Due to the large floor area and numerous internal partitions in high-rise buildings, wireless signals suffer significant attenuation, and outdoor macro base stations alone cannot provide reliable indoor coverage. To ensure adequate signal strength, high-power repeaters and indoor antenna distribution systems must be deployed inside the building.

A high-gain panel antenna is used as the donor (receiving) antenna and is installed on the rooftop wall facing the base-station tower, or in the direction where mobile test software shows the strongest signal. The donor antenna is connected to the repeater using a 1/2″ feeder cable with a length of no more than 50 meters.

Tunnel Coverage Solution

Tunnels vary widely in type and structure. Functionally, they can be classified as highway tunnels and metro/railway tunnels, each with different requirements for wireless coverage. Structurally, tunnels may be straight or curved, long or short, and these differences also affect the design of the coverage solution.

In most highway and rail tunnels, the demand for high-capacity voice and data services is moderate, so extending the coverage of existing outdoor base stations is usually sufficient.

Elevator Coverage Solution

Elevator shafts are narrow spaces enclosed by reinforced concrete and extending tens of meters in height. The elevator car and its doors are made of metal, which greatly attenuates mobile signals. Without a signal booster, mobile phones cannot be used reliably inside the elevator.

Amplitec’s C17L / A17L series elevator mobile signal booster provides a very cost-effective solution. The system consists of a C17L master unit and an A17L slave unit, and is available in single-band, dual-band, tri-band and multi-band models.

Countryside Coverage

In many mountain villages, mobile signals in the village are very weak because hills and forests block the line of sight to nearby base stations. Building new base stations or deploying fibre-remote solutions is often costly and difficult. Using high-power wireless repeaters to extend coverage is therefore the most economical and efficient solution.

A high-gain parabolic antenna is used as the donor (receiving) antenna and is installed on a hillside where the base-station tower is visible. A high-power outdoor wireless repeater is mounted near the top of the hillside and connected to the donor antenna with a 1/2″ feeder cable no longer than 50 metres.

Vehicle Coverage Solution

In rural and suburban areas, mobile operators typically deploy fewer base stations. Terrain features such as hills and trees can cause significant signal attenuation, and the vehicle body itself can further attenuate the base-station signal by about 15–20 dB. When a vehicle is travelling in such areas and the received signal level inside the car falls below −105 dBm, mobile phones may not work reliably. Installing an in-vehicle signal booster can greatly improve in-car coverage in areas with weak but existing base-station signals (however, if there is no network signal at all, the booster cannot restore coverage).

The main unit of the vehicle booster is usually mounted under the passenger seat. A magnetic-mount omnidirectional antenna is installed on the metal roof of the vehicle and used as the donor (receiving) antenna. The coaxial cable from the donor antenna is routed through the door-frame weather strip into the vehicle and connected to the BTS port of the vehicle booster.

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