Why Cellular Operators Are Building Smaller Cell Sites

Picocell in Beverly Hills

The most common thing I heard at the CTIA 2010 trade show this week at the Las Vegas Convention Center was that wireless operators will need more spectrum as they deploy WiMAX and LTE networks – generally marketed as 4G. This need was discussed twice within the opening hours of the show. First at the opening morning Raymond James Breakfast Roundtable which was part of the Tower Technology Summit co-located at CTIA and more notably in the opening key note address by Ralph de la Vega, President and CEO of AT&T Mobility and Consumer Markets. While earlier this month the FCC announced its plan to free up 500 MHz of spectrum in the next ten years, 300 MHz of which is expected within five years, the mobile operators can’t wait that long. New smartphones are fueling an insatiable consumer demand for applications that hog bandwidth, which in turn will require mobile operators to manage the spectrum they have more efficiently.

For me, this was the tone of this year’s trade show and thus raised the obvious question – what are carriers to do until they get the additional spectrum they need? Answer: Perform cell splits— decrease the cell radii and insert more cell sites to try to eek out more capacity with the limited spectrum they have. The simplified math works like this – you can have several users all downloading large amounts of data through one 4G cell site or you can break that site into multiple smaller cell sites to spread the consumer demand. By subdividing cell sites carriers can try to get more capacity out of their limited spectrum, at the risk of decreased efficiency and increased interference in the network.

These smaller cell sites are known as microcells, picocells and femtocells. Microcells usually have a cell radius of one mile or less. Picocells have a cell radius of a city block or less. The equipment for a picocell can be quite small, even deployed on light poles or street corners in dense, urban areas and are common in large public facilities like football stadiums, shopping centers, office buildings, airports, etc. And femtocells are typically private cell sites in a home or small office with four or less private users. Click here for a prior opinionpole.net blog on femtocells.

One thing is for sure, none of these three types of small cell sites are found on top of the typical cell tower. While there will always be a need for traditional cell towers, particularly for rural coverage, and high rooftop cell sites in urban areas, they are going to become less critical as network traffic begins to get off-loaded to these sites.

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