Small Cell Design (Indoor) – Physical Considerations
When doing any indoor small cell design, it is important to understand that every building is different. These physical difference need to be accounted for in the design. There are many soft RF considerations as well, however we will focus on the physical considerations here. These include:
- Small Cell Distance
- Floor Design
- Model Tuning
- Cable Runs
Small Cell Distance: The distance between small cells is also another issue. It is always better to keep 1.5 times cell radius to support UL services requested at cell edge. Cell radius depends on environment (warehouse, office space, hospital..etc.). If the distance between small cells are not kept and they are too close to each other, there will be more overlaps in the design and sniffing function of small cells is not working properly.
Capacity: Although coverage is typically the first aim of small cell design, capacity is another big concern. Small cells generally support 32 to 64 users simultaneously, depends on type of hardware. We have to make sure small cells support all users in that particular floor. Estimated capacity should be defined in survey stage and it needs to be addressed in design outputs.
Floor/Building Design: Another important factor is modeling the floor/building in design tool properly. In survey stage, it is advisable to take pictures of inside and outside of the building clearly. According to pictures and floor plans, building should be modeled with correct walls and materials. If modeling is not done properly, then losses of walls inside will be calculated inaccurate and it will affect design outputs.
Model Tuning: Like every design, model tuning will give more benefits in small cell design too. It is better to take measurements before and after design so you can calibrate your existing model. If you calibrate your model for different types of environments such as office spaces, warehouses, stores you can use same model for same type of venue in the future.
Cable Runs: In small cell designs, CAT-5 cables and fibers are necessary elements to connect small cells to core network. Switches are elements that every small cell need to be connected and they are the access points to IP gateway. There is a limitation in number of small cells connected to switch and cable lengths are also limited. If you have limited budget, putting small cell switches in optimum location will give you lots of benefits. Small cell design should be presented to customer and cable lengths, switch locations to be explained to avoid redesign in the future because of deployment restrictions.