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27 September 2013

Are Small Cells a Hard Sell?

Posted in Enterprise Mobility, Small Cells, WiFi, LTE

It depends. Small cells are necessary to satisfy the exploding demand in mobile data, no doubt about that. The reason behind this is that data consumption is expected to rise more than 1000 fold in less than 10 years (Qualcomm's 1000x Data Challenge). There are few possible ways to satisfy this large demand, namely, more spectrum, improved spectral efficiency (bps/Hz) and spatial reuse. Obviously, more spectrum will help but the fact of the matter is that spectrum is a scarce resource that by itself will not be enough to answer the looming challenge. Certainly, using Wifi with more than 600 MHz of unlicensed band will help. Further improving the spectral efficiency will soon face a barrier after exploiting advanced schemes like OFDM and MIMO. The main contribution will have to come through spatial reuse, where the spectrum is reused over small areas. Therefore, small cells are necessary!

Now, there are two types of small cells, one for outdoors and the other for indoors (enterprise), and they are inherently different from each other especially in their business case.

Outdoor small cells will be installed on utility and light poles, side of buildings, aerial strands, etc. These small cells are carrier-specific (support only a single operator) and will likely integrate LTE and WiFi radios. Outdoor small cells face several challenges like backhaul, power, rights of way, etc. Most utility or light poles do not have fiber access and may have to rely on wireless backhaul solutions like millimeter waves. In addition, constant power availability is not always guaranteed. Also, it will take time to negotiate with real-estate owners to mount the small cells on their property. Deployments of several 10's of thousands small cells are expected during 2013-2014 with more to come during 2015.

Enterprise small cells will likely follow a different business case mainly because of the BYOD trend. Enterprises will be reluctant to install a single operator on their premises and will rather support multi operators to support BYOD devices. The problem is that most if not all small cells today are operator-specific, and therefore, the enterprise will have to consider deploying multi small cells for each operator or service provider. This of course poses a great dilemma for enterprises as the solution will be costly due to multiple hardware and excess cabling, not to mention aesthetics of the interiors.

Because small cells are not universal (supporting multiple operators) many venues use a neutral-host solution in the form of distributed antenna system (DAS). The main problem with DAS is that it is a good coverage solution but not a good capacity solution. This is because the base station resources are shared across multiple antennas. In the days of voice-centric services DAS was a great solution, but for data-centric services coverage is necessary but not sufficient, and therefore the DAS has to be augmented with a capacity layer, for example, using small-cells in hotspot areas as well as using WiFi access points (AP).

In summary, small cells are here to stay, they are necessary for providing capacity. Outdoor small cells have some challenges that may be overcome overtime. The small cell outdoor model does not fit well in the enterprise that will rely for the time being on DAS and augmented layer using small cells and WiFi AP's. Ultimately, the best solution for the enterprise will come in the form of universal small cells.