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Small cells, big picture
Small cells have been the hot topic for 2011.
They have regularly been paraded on the catwalks of industry events as the saviour of networks struggling under the strain of mobile data growth.
But the underpinning backhaul solution is not as clear cut.
A scene has consistently been painted where thousands of femto, pico and WiFi based ‘small cells’ are deployed in urban environments – a vision likely to turn into reality (albeit long term) as mobile operators look to deliver highly targeted capacity to their customers.
But providing a backhaul solution to the small cells may not be as clear cut as originally thought.
There is a bigger picture to consider, where a solution may take a variety of forms.
It is in this space that a clear pecking order is starting to develop.
The most likely scenario, and one that appears to be most under discussion, is some form of multipoint microwave.
This may take the form of ‘line of sight’ (LOS) or ‘non line of sight’ (NLOS) as both solutions have the ability to aggregate traffic efficiently from a number of small cells.
The NLOS solutions might seem attractive at first, but because they are using narrow spectrum allocations the capacity available is limited and potentially restrictive.
Existing LOS solutions (as discussed in the last infocast) can be fast and cost effective to deploy and provide the required capacity improvements.
We may also see LOS solutions modified to develop a smaller access terminal form factor and to bring the cost down to an even lower level ready for widespread implementation.
And of course we can’t discount fibre.
The capacity it can offer is boundless – however it mustn’t be forgotten that the associated CAPEX is sufficiently high enough to prohibit widespread adoption.
The speed it takes to deploy fibre may also work against it.
Although fibre may be considered for the macro layer, the pace at which small cell networks need to be deployed favours a wireless solution.
So we think the small cell backhaul pecking order may look something like this - fibre where available, wireless LOS solutions if fibre isn’t possible for the majority of sites and NLOS if lower capacity will suffice.
However it is still early days and each solution has to prove itself to be economically viable and deliver the same reliability demanded of current backhaul networks.