As mentioned in the figure, at different heights we have different issues. When we provide an IBS we need to clearly identify the issue and then needed to provide a suitable solution for that. There are two types of IBS solutions:
- Distributed Antenna System (DAS) – mainly provided solution out of the two
- Nano BTS (2G) or Femto Cell (3G)
Distributed Antenna System (DAS)In a DAS solution we lay a network of antennas as required inside the building using splitters. Used equipment in a DAS solution:
- Symmetric (2way, 3 way, 4 way)
- Asymmetric (2way tapper)
- Omnidirectional Antenna
- Panel Antenna
Design Steps of a DAS
- Existing Coverage
- Antenna Locations
Then we need to plan the antenna types and their locations in each floor. Proposed antenna locations for the Ground floor and for the 1st floor are depicted in the Figure: Proposed Antenna Locations.
- Antenna Tree (EIRP Table)
After implementing the planned solution we do another drive test to verify the results. If a building is already covered using a DAS few other service providers can share the resources to provide their services. They only have to provide a BTS and they can use the existing antenna network.
Difficulties in DAS:
DAS should be installed when the building construction takes place. Otherwise it is difficult to set up it after the completion of the building construction.
Nano BTS (2G) or Femto Cell (3G)
Now the trend is towards IP based systems. Using a Nano BTS or a Femto cell we can easily solve issues inside a building. This solution is becoming popular in these days. Nano BTS is for 2G and Femto cell is to 3G. No need to do any construction to setup this service. These cells only require internet connectivity.