Thursday, February 23, 2023

Access Networks are Getting More Expensive

Like it or not, both mobile and fixed network operators are facing higher infrastructure costs. Fixed network operators must deploy optical fiber access networks. Mobile operators have to deploy dense small cell networks.


In each case, network architectures and investments are driven by physics: networks must support more bandwidth, which requires capacious physical media or small cells or both.


This is a good illustration of the reason why small cells are the future of mobile networks. It is just physics: the available radio frequencies we have added over time keep moving higher in the spectrum. Lower-frequency signals travel farther before they are attenuated.


Higher-frequency signals are attenuated quite quickly. The only available new spectrum we really can add is in the high-band areas. Those signals support lots of bandwidth, but will not travel very far, so cell sizes must necessarily be smaller. 

source: NTT, SKT 


And while small cells do not cost nearly what macrocells do (an order of magnitude less, at the very least), networks will need many more sites. The basics of cell geometry are that one quadruples the number of sites every time the cell radius shrinks by 50 percent. 


So shrinking from a 10-km radius to 50km radius requires four times as many cells. Shrinking again from 5 km to 2.5 km requires another quadrupling of sites, and so forth. By the time one moves to cell radii of 100 km or so, cell networks are quite dense. 


And optical fiber backhaul often is required to support such site. Ignoring the cost of many times more cells is the additional cost of fiber backhaul. 


So it should not be surprising that network cost is going up.


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