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Small Cells

12 December 2013

Could Unlicensed LTE Derail Carrier-WiFi Momentum?

Posted in Enterprise Mobility, Small Cells, WiFi, LTE

Not really. Unlicensed LTE is coming late to the party when there is already a solid base of WiFi devices, therefore, it will face some challenges, one of them is coexistence - it will be very challenging to coordinate the unlicensed LTE radio (synchronous) and the WiFi radio (asynchronous) operating in the same device or nearby. That is, there will be performance penalty when one radio is transmitting and the other is receiving. True, we have over 500 MHz unlicensed spectrum in the 5 GHz band but it will fill rather quickly especially when 11ac is using very wide channels, up to 160 MHz. There is also radar avoidance (DFS) requirement in the 5 GHz band that might further reduce the available spectrum. 

On the positive side, currently small-cells are not universal but rather carrier-specific. Indoor venues and enterprises will refrain from deploying multi carrier infrastructure because of duplication of backhaul, power, real-estate, aesthetics, etc. The unlicensed LTE will be able to emulate WiFi "multi-SSID" in the form of "multi LTE VLAN" each routed (IP) to the corresponding carrier, sort of a network-sharing approach which is welcome as the telecom market is transitioning to a commodity market.

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.