Less is more: How to gain 1-2Gps capacity with existing MW spectrum?

By Dudy Cohen 3 min read

I heard a particularly appropriate definition of economics: unlimited desires and limited resources.

Every day, telecommunication operators promote “unlimited” smartphone plans, offering “unlimited calls and texts” or “unlimited data.”

Subscribers take the bait, and the result is more demand for bandwidth. For them, it’s irresistible, enabling uninterrupted connectivity. And when they connect, they not only make phone calls but also stream HD video or use rich social media apps like Facebook, which adds almost six new users every second, YouTube, and Vimeo. Cumulatively, these apps require a huge amount of capacity.

But what about operators that need to fulfill their subscribers' desires for more bandwidth? For this, they need more capacity at the access points for each cell site and each sector. This leads to higher capacity requirements already in the backhaul. Right now, as an operator, you may only be limited to 500 Mbps over your wireless backhaul link. That’s only for current needs, where your narrowband spectrum may already be stretched. And there’ll be much more capacity demand as 4.5G or even 5G networks evolve.

Ultra-high capacity E-band spectrum (71GHz – 86GHz), which utilizes wideband channels, could be one approach to avoid congested networks. But the range is limited to around 3 miles (5 km), unsuitable for medium-long suburban/rural aggregation links. It only fits some metro network scenarios, such as short-distance, high-capacity links.

If only there was a way to quadruple capacity, leveraging your existing narrowband backhaul spectrum…

Well, there is!  Microwave technologies like 4x4 line-of-sight multiple input, multiple outputs (LOS MIMO). This technique uses multiple transmitters and receivers to create an artificial multi-path, deliberately transmitting two different signals over the frequency channel. Throughput increases X4 to up to 2Gbps per channel, enabling microwave networks to scale as capacity grows.

You also achieve an additional 3db gain and use smaller antennas, saving capital expenditures and increasing operational efficiency because they are simpler and less expensive to install -- no more cranes for a 6 ft (1.8 m) antenna. Or, you can use longer links, eliminating repeater sites. By using existing frequency, you also save up to 75% in frequency-license fees.

For more information, download Ceragon’s tech brief, “Boosting Microwave Capacity Using Line-of-sight MIMO.”

Download Tech Brief

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