Improving Rural Wireless Broadband

Microsoft has been implementing rural wireless broadband using white space spectrum – the slices of spectrum that sits between traditional TV channels. The company announced a partnership with ARK Multicasting to introduce a technology that will boost the efficiency of fixed wireless networks.

ARK Multicasting does just what their name implies. Today about 80% of home broadband usage is for video, and ISPs unicast video, meaning that the send a separate stream of a given video to each customer that wants to watch it. If ten customers in a wireless node are watching the same new Netflix show, the ISP sends out ten copies of the program. Today, in even a small wireless node of a few hundred customers an ISP might be transmitting dozens of simultaneous copies of the most popular content in an evening. The ARK Multicasting technology will send out just one copy of the most popular content on the various OTT services like Netflix, Amazon Prime, and Apple TV. This one copy will be cached in an end user storage device, and if a customer elects to watch the new content they view it from the local cache.

The net impact of multicasting should be a huge decrease in demand for video content during peak network hours. It would be interesting to know the percentage of video viewing in a given week comes from watching newly released content. I’m sure all of the OTT providers know that number, but I’ve never seen anybody talk about it. If anybody knows that statistic, please post in reply comments to this blog. Anecdotal evidence suggests the percentage is significant because people widely discuss new content on social media soon after it’s released.

The first trial of the technology is being done in conjunction with a Microsoft partner wireless network in Crockett. Texas. ARK Multicasting says that it is capable of transmitting 7-10 terabytes of content per month, which equates to 2,300 – 3,300 hours of HD video. We’ll have to wait to see the details of the deployment, but I assume that Microsoft will provide the hefty CPE capable of multi-terabyte storage – there are no current consumer settop boxes with that much capacity. I also assume that cellphones and tablets will grab content using WiFi from the in-home storage device since there are no tablets or cellphones with terabyte storage capacity.

To be effective ARK must be deleting older programming to make room for new, meaning that the available local cache will always contain the latest and most popular content on the various OTT platforms.

There is an interesting side benefit of the technology. Viewers should be able to watch cached content even if they lose the connection to the ISP. Even after a big network outage due to a storm, ISP customers should still be able to watch many hours of popular content.

This is a smart idea. The weakest part of the network for many fixed wireless systems is the backhaul connection. When a backhaul connection gets stressed during the busiest hours of network usage all customers on a wireless node suffer from dropped packets, pixelization, and overall degraded service. Smart caching will remove huge amounts of repetitive video signals from the backhaul routes.

Layering this caching system onto any wireless system should free up peak evening network resources for other purposes. Fixed wireless systems are like most other broadband technologies where the bandwidth is shared between users of a given node. Anything that removes a lot of video downloading at peak times will benefit all users of a node.

The big OTT providers already do edge-caching of content. Providers like Netflix, Google, and Amazon park servers at or near to ISPs to send local copies of the latest content. That caching saves a lot of bandwidth on the internet transport network. The ARK Multicasting will carry caching down to the customer level and bring the benefits of caching to the last-mile network.

A lot of questions come to mind about the nuances of the technology. Hopefully the downloads are done in the slow hours of the network so as to not to add to network congestion. Will all popular content be sent to all customers – or just content from the services they subscribe to? The technology isn’t going to work for an ISP with data caps because the cashing means customers might be downloading multiple terabytes of data that may never be viewed.

I assume that if this technology works well that ISPs of all kinds will consider it. One interesting aspect of the concept is that this means getting ISPs back into the business of supplying boxes to customers – something that many ISPs avoid as much as possible. However, if it works as described, this caching could create a huge boost to last-mile networks by relieving a lot of repetitive traffic, particularly at peak evening hours. I remember local caching being tried a decade or more ago, but it never worked as promised. It will be interesting to see if Microsoft and ARK can pull this off.

Continued Lobbying for White Space Spectrum

In May, Microsoft submitted a petition to the FCC calling for some specific changes that will improve the performance of white space spectrum used to provide rural broadband. Microsoft has now taken part in eleven white space trials and makes these recommendations based up on the real-life performance of the white space spectrum. Not included in this filing is Microsoft’s long-standing request for the FCC to allocate three channels of unlicensed white space spectrum in every rural market. The FCC has long favored creating just one channel of unlicensed white space spectrum per market – depending on what’s available.

A number of other parties have subsequently filed comments in support the Microsoft proposals including the Wireless Internet Service Providers Association (WISPA), Next Century Cities, New America’s Open Technology Institute, Tribal Digital Village and the Gigabit Libraries Network. One of the primary entities opposed to earlier Microsoft proposals is the National Association of Broadcasters (NAB), which worries about interference with TV stations from white space broadband. However, the group now says that it can support some of the new Microsoft proposals.

As a reminder, white space spectrum consists of the unused blocks of spectrum that are located between the frequencies assigned to television stations. Years ago, at the advent of broadcast television, the FCC provided wide buffers between channels to reflect the capability of the transmission technology at the time. Folks my age might remember back to the 1950s when neighboring TV stations would bleed into each other as ghost signals. As radio technology has improved the buffers are now larger than needed and are larger than buffers between other blocks of spectrum. White space spectrum is using those wide buffers.

Microsoft has proposed the following:

  • They are asking for higher power limits for transmissions in cases where the spectrum sits two or more channels away from a TV station signal. Higher power means greater transmission distances from a given transmitter.
  • They are asking for a small power increase for white space channels that sit next to an existing TV signal.
  • They are asking for white space transmitters to be placed as high as 500 meters above ground (1,640 feet). In the US there are only 71 existing towers taller than 1,000 feet.
  • Microsoft has shown that white space spectrum has a lot of promise for supporting agricultural IoT sensors. They are asking the FCC to change to white space rules to allow for narrowband transmission for this purpose.
  • Microsoft is asking that the spectrum be allowed to support portable broadband devices used for applications like school buses, agricultural equipment and IoT for tracking livestock.

The last two requests highlight the complexity of FCC spectrum rules. Most people would probably assume that spectrum licenses allow for any possible use of spectrum. Instead, the FCC specifically defines how spectrum can be used and the rural white space spectrum is currently only allowed for use as a hot spot or for fixed point-to-point data using receiving antennas at a home or business. The FCC has to modify the rules to allow use for IoT for farms sensors, tractors and cows.

The various parties are asking the FCC to issue a Notice of Proposed Rulemaking to get comments on the Microsoft proposal. That’s when we’ll learn if any other major parties disagree with the Microsoft proposals. We already know that the cellular companies oppose providing multiple white space bands for anything other than cellular data, but these particular proposals are to allow the existing white space spectrum to operate more efficiently.

White Space Spectrum for Rural Broadband – Part II

Word travels fast in this industry, and in the last few days I’ve already heard from a few local initiatives that have been working to get rural broadband. They’re telling me that the naysayers in their communities are now pushing them to stop working on a broadband solution since Microsoft is going to bring broadband to rural America using white space spectrum. Microsoft is not going to be doing that, but some of the headlines could make you think they are.

Yesterday I talked about some of the issues that must be overcome in order to make white space spectrum viable. It certainly is no slam dunk that the spectrum is going to be viable for unlicensed use under the FCC spectrum plan. And as we’ve seen in the past, it doesn’t take a lot of uncertainty for a spectrum launch to fall flat on its face, something I’ve seen a few times just in recent decades.

With that in mind, let me discuss what Microsoft actually said in both their blog and whitepaper:

  • Microsoft will partner with telecom companies to bring broadband by 2022 to 2 million of the 23.4 million rural people that don’t have broadband today. I have to assume that these ‘partners’ are picking up a significant portion of the cost.
  • Microsoft hopes their effort will act as a catalyst for this to happen in the rest of the country. Microsoft is not themselves planning to fund or build to the remaining rural locations. They say that it’s going to take some combination of public grants and private money to make the numbers work. I just published a blog last Friday talking about the uncertainty of having a federal broadband grant program. Such funding may or may not ever materialize. I have to wonder where the commercial partners are going to be found who are willing to invest the $8 billion to $12 billion that Microsoft estimates this will cost.
  • Microsoft only thinks this is viable if the FCC follows their recommendation to allocate three channels of unlicensed white space spectrum in every rural market. The FCC has been favoring creating just one channel of unlicensed spectrum per market. The cellular companies that just bought this spectrum are screaming loudly to keep this at one channel per market. The skeptic in me says that Microsoft’s white paper and announcement is a clever way for Microsoft to put pressure on the FCC to free up more spectrum. I wonder if Microsoft will do anything if the FCC sticks with one channel per market.
  • Microsoft admits that for this idea to work that manufacturers must mass produce the needed components. This is the classic chicken-and-egg dilemma that has killed other deployments of new spectrum. Manufacturers won’t commit to mass producing the needed gear until they know there is a market, and carriers are going to be leery about using the technology until there are standardized mass market products available. This alone could kill this idea just as the FCC’s plans for the LMDS and MMDS spectrum died in the late 1990s.

I think it’s also important to discuss a few important points that this whitepaper doesn’t talk about:

  • Microsoft never mentions the broadband data speeds that can be delivered with this technology. The whitepaper does talk about being able to deliver broadband to about 10 miles from a given tower. One channel of white space spectrum can deliver about 30 Mbps up to 19 miles in a point-to-point radio shot. From what I know of the existing trials these radios can deliver speeds of around 40 Mbps at six miles in a point-to-multipoint network, and less speed as the distance increases. Microsoft wants multiple channels in a market, because bonding multiple channels could greatly increase speeds to perhaps 100 Mbps. But even with one channel this is great broadband for a rural home that’s never had broadband. But the laws of physics means these radios will never get faster and those will still be the speeds offered a decade and two from now when those speeds are going to feel like slow DSL does today. It seems like too many broadband technology plans fail to recognize the fact that our demand for broadband has been doubling every three years since 1980. What’s pretty good speeds today can become inadequate in a surprisingly short period of time.
  • Microsoft wants to be the company to operate the wireless databases behind this and other spectrum. That gives them a profit motive to spur the wireless spectrums to be used. There is nothing wrong with wanting to make money, but this is not a 100% altruistic offer on their part.

It’s hard to know what to conclude about this. Certainly Microsoft is not bringing broadband to all of rural America. But it sounds like they are willing to work towards making this work. But we can’t ignore the huge hurdles that must be overcome to realize the vision painted by Microsoft in the white paper.

  • First, the technology has to work and the interference issues I discussed in yesterday’s blogs need to be solved for anybody to trust using this spectrum on an unlicensed basis. Nobody will use this spectrum if unlicensed users constantly get bumped off by licensed ones. The trials done for this spectrum to date were not done in a busy spectrum environment.
  • Second, somebody has to be willing to fund the $8B to $12B Microsoft estimates this will cost. There may or may not be any federal grants ever available for this technology, and there may never be commercial investors willing to spend that much on a new technology in rural America. The fact that Microsoft thinks this needs grant funding tells me that a business plan based upon this technology might not stand on its own.
  • Third, the chicken-and-egg issue of getting over the hurdle to have mass-produced gear for the spectrum must be overcome.
  • Finally, the FCC needs to adopt Microsoft’s view that there should be 3 unlicensed channels available everywhere – something that the licensed holders are strongly resisting. And from what I see from the current FCC, there is a god chance that they are going to side with the big cellular companies.

White Space Spectrum for Rural Broadband – Part I

Microsoft has announced that they want to use white space spectrum to bring broadband to rural America. In today and tomorrow’s blog I’m going to discuss the latest thoughts on the white space spectrum. Today I’ll discuss the hurdles that must be overcome to use the spectrum and tomorrow I will discuss in more detail what I think Microsoft is really proposing.

This spectrum being called white space has historically been used for the transmission of television through the air. In the recent FCC incentive auction the FCC got a lot of TV stations to migrate their signals elsewhere to free up this spectrum for broadband uses. And in very rural America much of this spectrum has been unused for decades.

Before Microsoft or anybody can use this spectrum on a widespread basis the FCC needs to determine how much of the spectrum will be available for unlicensed use. The FCC has said for several years that they want to allocate at least one channel of the spectrum for unlicensed usage in every market. But Microsoft and others have been pushing the FCC to allocate at least three channels per market and argue that the white space spectrum, if used correctly, could become as valuable as WiFi. It’s certainly possible that the Microsoft announcement was aimed at putting pressure on the FCC to provide more than one channel of spectrum per market.

The biggest issue that the FCC is wrestling with is interference. One of the best characteristics of white space spectrum is that it can travel great distances. The spectrum passes easily through things that kill higher frequencies. I remember as a kid being able to watch UHF TV stations in our basement that were broadcast from 90 miles away from a tall tower in Baltimore. It is the ability to travel significant distances that makes the spectrum promising for rural broadband. Yet these great distances also exacerbate the interference issues.

Today the spectrum has numerous users. There are still some TV stations that did not abandon the spectrum. There are two bands used for wireless microphones. There was a huge swath of this spectrum just sold to various carriers in the incentive auction that will probably be used to provide cellular data. And the FCC wants to create the unlicensed bands. To confound things, the mix between the various users varies widely by market.

Perhaps the best way to understand white space interference issues is to compare it to WiFi. One of the best characteristics (and many would also say the worse characteristics) of WiFi is that it allows multiple users to share the bandwidth at the same time. These multiple uses cause interference and so no user gets full use of the spectrum, but this sharing philosophy is what made WiFi so popular – except for the most crowded environments anybody can create an application using WiFi and knows that in most cases the bandwidth will be adequate.

But licensed spectrum doesn’t work that way and the FCC is obligated to protect all spectrum license holders. The FCC has proposed to solve the interference issues by requiring that radios be equipped so that unlicensed users will first dynamically check to make sure there are no licensed uses of the spectrum in the area. If they sense interference they cannot broadcast, or, once broadcasting, if they sense a licensed use they must abandon the signal.

This would all be done by using a database that identifies the licensed users in any given area along with radios that can search for licensed usage before making a connection. This sort of frequency scheme has never been tried before. Rather than sharing spectrum, like WiFi, the unlicensed user will be only allowed to use the spectrum when there is no interference. As you can imagine the licensed cellular companies, which just spent billions for this spectrum are worried about interference. But there are also concerns by churches, city halls and musicians who use wireless microphones.

It seems unlikely to me that in an urban area with a lot of usage on the spectrum that unlicensed white space spectrum is going to be very attractive. If it’s hard to make or maintain an unlicensed connection then nobody is going to try to use the spectrum in a crowded-spectrum environment.

The question that has yet to be answered is if this kind of frequency plan will work in rural environments. There have been a few trials of this spectrum over the past five years, but those tests really proved the viability of the spectrum for providing broadband and did not test the databases or the interference issue in a busy spectrum environnment. We’ll have to see what happens in rural America once the cellular companies start using the spectrum they just purchased. Because of the great distances in which the spectrum is viable, I can imagine a scenario where the use of licensed white space in a county seat might make it hard to use the spectrum in adjoining rural areas.

And like any new spectrum, there is a chicken and egg situation with the wireless equipment manufacturers. They are not likely to commit to making huge amounts of equipment, which would make this affordable, until they know that this is really going to work in rural areas. And we might not know if this is going to work in rural areas until there have been mass deployments. This same dilemma largely sunk the use fifteen years ago of the LMDS and the MMDS spectrums.

The white space spectrum has huge potential. One channel can deliver 30 Mbps to the horizon on a point-to-point basis. But there is no guarantee that the unlicensed use of the spectrum is going to work well under the frequency plan the FCC is proposing.

More on White Space Wireless

001-Signal-Command-SSILast July I wrote about the Google database that shows the availability of white space radio spectrum in the US. This is spectrum that has been used for years by UHF television stations. In some rural places it was never used and in others it has been freed up as stations have moved elsewhere.

I’ve been hearing about this spectrum a lot lately so I thought I’d talk a little more about it. There are now several trials of the spectrum going on in the US. The first test market was the City of Wilmington NC who implemented this in their municipal network in 2010. They use it to control traffic lights, for public surveillance cameras and other municipal uses. Probably the biggest US test so far is a campus-wide deployment at West Virginia University in Morgantown that launched in July 2013. There only look to be a few dozen of these trials going on worldwide.

So what are the pros and cons of this technology and why isn’t it being deployed more? Consider some of the following:

  • It’s not available everywhere. That’s why Google and others have put together the maps. Where there are still TV stations using some of the bandwidth, only the unused portion of spectrum is available. There are still large areas around most major metros that have some use in the spectrum.
  • This is still a trial provisional spectrum and the FCC has to approve your trial use. I’m not sure why this is taking so long, because the Wilmington test has been going on since 2010 and supposedly has no interference issues. But I guess the FCC is being very cautious about letting WISPs interfere with television signals.
  • We are at that awkward point that happens with all new uses of spectrum, where there is equipment that will work with the spectrum, but that equipment won’t get really cheap until there is a lot of demand for it. But until that demand is believed by a manufacturer, not much happens. It was this equipment cost barrier that killed the use of LMDS and MMDS spectrum in the 90s. There is no equipment on the market yet that would let white space be used by laptops, cell phones or tablets. Instead it must feed a traditional WiFi router.
  • One use of the spectrum is that it can make a better hotspot. I don’t think most people understand the short distances that can be achieved with hotspots today. A 2.4 GHz WiFi signal can deliver just under 100 Mbps out to about 300 feet. But it dies quickly after that and there may 30 Mbps left at 600 feet and nothing much after that. If they put whitespace receivers into laptops this spectrum can deliver just under 50 Mbps out to 600 feet and 25 Mbps out to 1,200 feet. And there is an additional advantage to white space in that it travels fairly free through walls and other barriers.
  • The real potential for the spectrum is to extend point-to-multipoint radio systems. With white space you can deliver a little less than 50 Mbps up to about 6 miles from the transmitter. That’s easily twice as far as the distances that can be achieved today using unlicensed spectrum and a 12-mile circle around a transmitter can make for viable economic returns on an investment. Physics limits this to about 45 Mbps of total bandwidth meaning that a product of 40 Mbps download and 5 Mbps upload is possible. That is certainly not fiber speeds, but it would be a great rural product. The problem comes in in the many places where part of the spectrum is still in use, and in those places the radios would have to work around the used spectrum and the speeds would be correspondingly slower.

It seems like this is a spectrum with a lot of potential, especially in rural places where there are no existing uses of the spectrum. This could be used for new deployments or for supplementing existing WiFi deployments for WISPS. There is equipment that works on the spectrum today and I guess we are now waiting for the FCC here and regulatory bodies around the world to open this up to more use. The US isn’t the only place that used this spectrum for TV and much of the rest of the world shares the same interference concerns. But if this is ever released from the regulatory holds I think we would quickly hear a lot more about it.