Following on from my last post, I recently read an article in Mobile Europe which referred to the Infonetics Research report about cellular operators’ views on small cells.
In my experience, Distributed Antenna Systems (DAS) are still proving to be very popular with the operators, particularly for larger venues like airports, shopping malls and sports arenas. Operators also mention that one of the issues with small cells is interference with the macro network.
Ideally, a cell in a network should have an equally strong signal level throughout the entire cell area with a rapid drop in signal strength as the cell border is reached. A DAS solution with several antennas in the cell creates a condition which is very close to perfect. The interference between cells is created in the overlapping areas.
Small cells with a single antenna site will give rather large overlapping areas between cells unless the cell area is limited by walls or other structures with large attenuation. In this scenario, the interference between cells results in loss of capacity on the network.
A good example of how cell coverage should be optimised to reduce interference was demonstrated in London earlier this year. During the Olympic and Paralympic Games, network capacity in the big stadiums was one of the most critical issues for the UK Operators. All three frequency bands (900, 1800 and 2100MHz) had to be used in all stadium areas to create the required capacity. The stadium seats were divided into many sectors, each sector being served by several base stations in a giant multi-operator DAS solution. Panel antennas with a very special radiation pattern were used to cover each of the sectors in the stadiums. The overlapping areas between sectors were very small, resulting in minimal capacity losses due to interference.
You can click here to take a look at our case study video on London 2012, and the DAS deployment used in the different venues.
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