For many years, I’ve said that the first rule of high-density wireless network design is to use the 5 GHz spectrum. You have three 20 MHz channels in 2.4 GHz, and have to share it with everything else that operates in 2.4: microwaves (the reason the band is set aside to begin with), cordless phones, video bridges, and so on.
At 5 GHz, the air is just cleaner. Instead of three crowded narrow channels, you have ten wide channels. If there’s something that’s valuable to you, would you rather have 83 or 400?
At Aerohive, one of the ways that we make high-density networks better is to support (actually, strongly encourage!) the use of the 5 GHz band. Virtually all of our customers buy dual-band access points (APs), and many enable our band-steering capabilities to ensure that they are using the clean spectrum up at 5 GHz.
One of the difficulties that many of our customers have is that low-power devices are almost exclusively 2.4 GHz. Roughly speaking, the electrical power required to run an oscillator goes as the square of frequency, so 2.4 GHz components can use as little as a quarter of the power of their nearly-identical 5 GHz cousins.
As a result, most battery-operated devices are 2.4 GHz only, and devices for which battery life is at a premium – that is, every phone on the market until yesterday – are constrained to the crowded frequency band that’s been used since the mid-1990s.
The iPad was one of the first battery-operated devices to use a dual-band (2.4 GHz and 5 GHz radio), in recognition of the need to operate on large networks to support the plethora of business applications. Yesterday, it was joined by the iPhone. The iPhone 5 has not just a dual-band radio, but a 2-stream radio.
How’s your network coverage for phones? Better make it five by five. (“Five by five” is an aviation term meaning that your radio signal is loud and clear, and an important phrase to hear as a student pilot when you’re doing the preflight check of the radio.)
