Originally posted Sept 21, 2016
No—but the way forward has implications for RF and microwave testing
In Electronic Design, Lou Frenzel recently asked a couple of provocative questions, and in this post I’d like to look at both from a different angle (I previously discussed one in the context of engineering imagination). Specifically, Lou wondered whether communications data rates have really maxed outand whether smartphones have peaked. He is taking a forward look through the mists of time and, as I once learned as a product-line forecaster, “It is difficult to make predictions, especially about the future.” *
Back then, my experience made it clear I was no seer and, on a consistent basis, nobody else was either. Nature seems to abhor this sort of thing. However, I could be Captain Obvious and do a good job pointing out big things that were relatively clear. I’d like to take a stab at that here.
First, data rates: We all know that what matters in the end is effective data rate, the actual rate—including latency—that you or I or our customers can get at any given time and place. By that standard there is a lot that needs to be done, and a lot that can be done.
There is no talk of repealing Shannon-Hartley, but modern systems are aiming for MIMO up to 8×8 and QAM as dense as 4096 to crowd more bits into the available hertz in a practical fashion. Combine these techniques with wider bandwidths and more OFDM subcarriers and the potentialdata rates are seriously impressive: LTE-A proposes 1.6 Gbps for wireless, and DOCSIS 3.1 promises a 10 Gbps wired downstream link.
Denser constellations encode more bits in each symbol, increasing data rates for a given bandwidth. This VSA display of errors and coding includes a constellation of 4096 states or 12 bits/symbol.
Spectral efficiency is just the platform for a host of improvements and enhancements that will deliver more data in more places. That’s the key to the effective data rates that matter much more than the theoretical ones in the press releases.
In my experience, the inability to get 20 Mb/s in any particular location pales in comparison to the inability to get even 1 Mb/s in so many locations. Even IoT and smart homes or businesses generally prioritize a reliable connection over a high data rate.
Fat pipes for direct connections and backhaul will help because high capacity can usually be sliced up to give more users an adequate sliver of the bandwidth pie. Adaptive and cognitive systems can make the most of the existing and evolving environment. Beamforming and small—pico or femto—cells can make better use of the local RF landscape. Multi-mode devices can use the best one of several radios to move the data of the moment.
Millimeter frequencies are yet another approach to matching a need with an improving technology. These can exploit the (currently) open country of much higher frequencies and bandwidths, and turn limited range into an advantage in situations such as wireless video, where frequency reuse can be room-to-room.
I won’t try to predict details, but I know this is good news for RF engineers. All these tactics for increasing effective data rate require innovative design and manufacturing to yield devices that perform well enough, meet standards, and hit the cost targets essential to success in the marketplace.
As for Lou’s speculation that smartphones may have peaked, he may be right about smartphonesper se, but I look at this in a different way. Those glossy little (or not) slabs should instead be seen as the computer/communications/information/audio-video image device you have with you constantly—and “smartphone” sells them short. Seen in that light, the opportunity for transformative growth is huge.
Consider virtual and augmented reality, especially in the context of the explosive success of apps such as Pokemon Go. The need for high-resolution, low-latency video will drive data rates and the evolution of the things we call smartphones in directions most of us haven’t yet imagined. While the value and wisdom of those directions is open to debate, the demands on RF design and test seem very clear to this Captain Obvious.
* Attributed to everyone from Niels Bohr to Yogi Berra, but probably from a Danish humorist in 1948 or earlier.