There are currently thousands of broadband wireless networks now operating successfully in unlicensed spectrum in more than 120 countries around the world. What about them?
What's their secret?
It's not much of a secret really. It's simply operating networks carefully planned and designed to provide optimum reliability in the unlicensed spectrum.
The Case for Unlicensed Frequencies
The fact is, in certain scenarios—such as extending a network over rough terrain or needing to deploy exceptionally cost-effective fixed point-to-point and point-to-multipoint solutions—unlicensed frequency networks have a lot to offer.
Of course, unlicensed spectrum has some challenges in trying to provide the same degree of reliability as licensed spectrum. But that doesn't necessarily mean it's unreliable. It just means you have to be aware of the issues inherent in the unlicensed band. It means you have to choose your equipment very carefully. And it means you have to design reliability into your network from the beginning. When you can do that, you can make a very strong business case for building a carefully designed high-speed wireless network in unlicensed spectrum.
Designing for Robust Reliability
Unlicensed spectrum is free. But just because it doesn't cost anything doesn't mean you don't have the right to expect it to be reliable. How do you design reliability into an unlicensed broadband wireless network? First of all, it takes planning. As in any solution, one size does not fit all. To choose the right unlicensed frequency solution, you have to thoroughly understand your network's specific needs.
You have to understand your customers' needs, too. You have to plan to offer the breakthrough highspeed applications your subscribers and prospects are demanding. Access to virtually anywhere and everywhere. Speed. Music. Video. Interactivity. You also have to set up a comprehensive network management system. And you have to be careful to choose network equipment that has proven to be reliable in the field, not just in the laboratory. And, of course, you have to plan for success and expansion.
The Outer Limits
We all learned it in Wireless 101. "The farther you go, the weaker the signal." When you're using unlicensed spectrum, the edges of your network are especially vulnerable to interference from other users of the unlicensed band. The question becomes, do you want to try to push service to the absolute outer edges of your system? If you do, you risk the chance that someone will put up a transmitter or other equipment that will quite literally interfere with your ability to serve your customers.
The fact is, reliability is better served by creating a "cushion" that will allow all your customers to enjoy reliable service, no matter where they're located in the network. This cushion is known as fade margin, or allowance for fluctuations in signal strength caused by interference; transmitter or receiver movement; or reflections or scattering due to obstacles in the area. Many broadband wireless systems have a fade margin of 10 db. When you're designing for reliability in unlicensed spectrum, however, it's crucial to select technology that operates reliably with lower fade margins, even as low as 3 db.
Mitigating Against Interference
Some unlicensed network operators have learned a hard truth about how operating in unlicensed spectrum can affect growth. The truth is this: the size of your network matters. The larger your network grows, the more subscribers you gain, the more you're going to experience self-interference.
More important, your customers will, too. As a great many unlicensed operators have discovered, if you want both reliability and scalability in unlicensed frequencies, having GPS synchronization is a must. Because GPS Synchronization is technology that ensures that your network won't interfere with itself.
The sad fact is, some networks have experienced major interference problems as they've grown ultimately resulting in the need to rip out the existing network and replace it with totally new technology. Technology that is specifically designed to support service and growth in unlicensed spectrum.
How do you solve these scalability and interference issues before they become problems? By making sure you build a network that includes GPS synchronization to reduce self-interference, helping you make more reliable, more efficient, more cost-effective use of unlicensed frequencies. And enabling you to add subscribers and capacity seamlessly, without having to redesign your network every time you change it.
