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High capacity backhaul for small cells
My colleague Julius Robson has previously written about the relative amounts of spectrum available in the sub-6GHz or ‘NLOS’ (non-line of sight), bands and the usual microwave and millimetre wave bands used for backhaul.
In summary, above 6GHz there is more than twenty times as much backhaul spectrum available as below, with the obvious consequences for the relative cost of bandwidth above or below this division.
For this reason, we see LOS (>6GHz) microwave solutions as becoming the mainstay of small cell backhaul, just as they have been for macro backhaul for many years now.
Of course there is a place for sub-6GHz solutions as we illustrate in the following chart - it’s just that the relative shortage of spectrum makes it uneconomical to use in the majority of cases.
So I was very interested to read Ericsson’s recent paper non-line-of-sight microwave backhaul for small cells which compares the throughput of 28GHz and 5.8GHz backhaul systems in various NLOS configurations.
Their conclusion is that “contrary to common belief … microwave backhaul in bands above 20GHz will outperform sub-6GHz systems under most NLOS conditions”.
The Ericsson results closely match our experience using VectaStar at 28GHz to backhaul a small cell network for O2 in London.
It seems then, that we can extend the use of high frequency microwave solutions even further into the adverse location part of the small cell distribution curve.
This is great news for operators because multipoint microwave solutions offer compelling TCO benefits, resilience and solution maturity combined with capacity that far outstrips sub-6GHz systems.
We’ll return to this topic in a couple of weeks when we’ll see how multipoint microwave lets us exploit the statistical properties of backhaul traffic to maximise efficiency in our backhaul network.