Sunday, December 4, 2011

Small Cells Mean New Needs for Backhaul

Backhaul is a crucial enabler for mobile operators deploying Long Term Evolution networks. For starters, the amount of backhaul required is an order of magnitude up to two orders of magnitude greater than for 2G and 3G networks. Also, to minimize overall  network costs, mobile service providers are turning to small cell architectures that spot-deploy transmitters in high-traffic areas, rather than relying on use of additional frequencies and bandwidth. 

Also, the deployment of small cells in dense urban environments means traditional methods of forwarding traffic from one macro-cell site to another, before being passed off to the core network, are not always possible. 

Where it comes to small mobile cell sites, which will, by definition, cover small areas primarily in high-traffic areas, backhaul costs will have to scale to match the large number of sites, and the relatively small number of customers served at any single site. That also means new techniques will be needed.

That suggests wireless backhaul will be important, for cost reasons. There are three main categories of contending wireless backhaul solutions, many will note, including:
1 Line-of-sight (LOS) microwave systems typically operating in the 10 GHz – 42 GHz bands.
2. “E-band” LOS solutions that operate in the 60 GHz band (or in some cases at 80 GHz).
3. Non-line-of-sight (NLOS) utilizing sub 6 GHz licensed TDD spectrum. The Options for Small Cell Wireless Backhaul

In some cases, fixed network solutions might also be affordable, though it is unikely a fiber connection often will fall into that category. 

For that reason, a new approach to small-cell backhaul is required to bring down the per-megabit costs. Small cells are forcing vendors to rethink wireless backhaul for an environment where most cell locations are not in line of site with each other or with aggregation points. That means the traditional approach of relaying traffic from one tower to another before handing off to the fixed backhaul network is not possible. 

Also, new levels of cost optimization are needed, as the total cost of deploying dense small cell networks would be excessive, compared to other bandwidth approaches, without a new lower cost parameters.  Small cell backhaul costs

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