I’m surprised to see that we are just a couple of days away from Halloween. It makes me wonder where the month has gone. It’s been a hectic travel month that started with a trip to visit my cousin April in the woods of the Adirondack Mountains. In my last blog, I described how I wouldn’t have cellular service, but in an interesting commentary on connectivity, the Wi-Fi coverage would be as good as or better than what I get outside of Boston with my DOCSIS 3.0 cable service. The visit was great, I love seeing April and catching up and she always goes out of her way for me. It was a bit jarring that the red house I remember from my childhood is now brown…but life, like networks and technology evolves! I was right about connectivity; there wasn’t enough cellular signal to send a text, but Wi-Fi kept me tethered to the Internet. If you read this blog, April, no worries, I will be back!

From the Adirondack Mountains, I wound up below sea level in New Orleans for the SCTE Cable-Tec Expo '15 where the discussion was also about DOCSIS, cellular and Wi-Fi. Surprisingly, the discussion of Wi-Fi and wireless seemed a bit more incongruous at a cable conference than the brown house in the mountains. In fact, one of my big takeaways from the conference is how quickly and completely the cable/broadband industry has embraced Wi-Fi and “alternative” wireless methods, like TV white space (TVWS) channels.

Wi-Fi interest from this wired industry is surprising only in how quickly the wireless technology has been adopted as “one of our own”. At last year’s conference, the MSOs were talking about how they could stitch together a network based on Wi-Fi access points. They felt that there are solvable technical challenges, but the biggest challenge was to figure out ways to monetize this network. Fast forward a year and operators are implementing VoWi-Fi calling, Comcast has 11 million public Wi-Fi access points through its Xfinity broadband service and MSOs feel they are making good headway monetizing this ever-expanding network of hot spots that currently stands at just over 12 million.

Not everything is completely hunky dory between wired and wireless broadband, however. One of the hottest topics in the wireless industry is the use of LTE in the unlicensed 5 GHz ISM band, variously known as LTE-U, LAA or LTE-LAA. The Wi-Fi supporters and the cable industry, by association, are especially concerned about interference between the signals in this band. There is a flurry of activity from both camps, with each trying to state their case and mitigate or eliminate any issues. At best, this is currently a very uneasy truce, with both sides eying the other with suspicion.

With this backdrop, imagine my surprise when I saw a presentation describing how LTE and Wi-Fi, along with TVWS as a backhaul medium can provide high-speed internet access and voice service to underserved areas. TVWS channels are the 6 MHz guard-band channels originally used in analog TV. The vast majority of viewers have migrated to digital TV, so these white space channels are now available. The US officially transitioned to digital TV in 2009, so this concept is not new, but applications for this free spectrum have been slow to emerge. Why are TVWS channels interesting in the case of underserved broadband/cellular areas?

I think the chart below sums up the situation elegantly. It shows the availability of TVWS channels in the US and the number appears to be inversely proportional to population density. Not surprisingly, the more populated areas have less availability, reflecting several TV stations serving the same areas, more channels, etc. That is not a problem, because these areas also are likely to have good cellular coverage, with high-speed broadband readily available. The interesting part of the chart is the large number of TVWS channels that are available in the less populated areas of the country where access to broadband and cellular service may be challenging. The presentation described a scenario of deploying LTE base stations in a mesh configuration in rural areas. In these areas, the only viable means of backhaul is wireless and the thesis is that TVWS channels can provide a more robust, less expensive link than microwave or millimeter wave radios. Setting up the LTE network as a mesh means that the signals will route between base stations until they reach a Wi-Fi or some other wired transport network.

Source: Rate Optimal Backhaul and Distribution Using LTE in TVWS, Sudhir B. Pattar Rutgers University

So, other than illustrating a scenario where Wi-Fi and LTE can provide value if they can coexist, what does this have to do with compound semiconductor devices? If you are a regular reader of this blog, you know that I often talk about the vision of the future where most everything is connected and ask the question of how this future looks to the large portions of the world population that doesn’t have access to broadband or reliable cellular coverage. This problem only gets worse as 5G starts to get defined and deployed. From the network standpoint, any idea or architecture that allows deployment farther away from densely populated areas will increase data traffic. This increases the need for more and better performing semiconductor processes and components in response. It also lessens the chance that the future will be divided into the “haves” and “have nots” when it comes to taking advantage of the services that high-speed broadband will enable.

Who knows? Maybe the next time I go to visit April, she will have wireless broadband all over the woods!

-Eric