Communications

No spectrum shortage, just an allocation problem

2011-09-29T12:10:52-04:00

As a new study from Citi Investment Research & Analysis make clear, the US does not have a spectrum shortage. We've just allowed a relatively small number of carriers to control the spectrum. Quoting the study's summary:

Today, US carriers have 538MHz of spectrum. And, additional 300MHz of additional spectrum waiting in the wings. But, only 192MHz is in use today.

Perhaps if we had an effective "use it or lose it" policy in place, or a heavy tax on unused spectrum a more vibrant market for this spectrum would emerge. But today, the problem is not a shortage of spectrum but the fact that what's out there is not being utilized.

Obviously things vary by geography, but Citi's summary is completely justified. Their methodology is thorough both as to who owns what and what is deployed county-by-county for 3100 separate counties. Here's the summary of what's in use:

and here are the details on what's currently owned by US carriers:

So why would we repack the TV broadcasters and auction off that spectrum when we've just finished putting in place unlicensed access to TV white spaces? Unlicensed spectrum will be heavily utilized while more exclusively owned spectrum will just add to the pool of under utilized resources.

Limitations of Carrier Grade NAT, and some workarounds

2011-09-16T10:42:36-04:00

Qtel, the largest carrier in Qatar (and nearly the only Internet provider) appears to connect all their users (~600K) to the Internet through just one or a very few public IPv4 addresses. 82.148.97.69 was their single public address in 2006-2007. How can network address translation (NAT) put all those users through just one IP address?

Well, both UDP and TCP include 16-bit port numbers, so for each IP address there are 2**16 = 65,536 unique IP address/ TCP port number combinations which can support network address translation (NAT) for more than 65K simultaneous connections. Of course, individual browser sessions may open multiple connections so each on-line user can tie up several such connections, even several dozen.

But there are more unique fields that come into play. On the Internet side of the NAT, each active IP session has five fields of interest: source IP address, source port, protocol, destination address; destination port. So you can use the same source address and port number for multiple independent sessions if the sessions are going to different destinations or using different protocols. With this approach, one public IP address can clearly support millions and millions of connections.

But what if most of your users are trying to reach just a few destination addresses? That’s a problem Qtel had (or at least their users had) when accessing Wikipedia in 2006.

One obvious solution is to devote more than one public IP address for the whole country! Indeed, if a few hundred people are attempting to access the same address simultaneously, then having a few hundred IP addresses (for the whole country!) would do it. Of course, if the destination IP address is that of Google’s search bar, you might need more than a few hundred IP addresses.

There is another path, one which Geoff Huston alludes to in a recent article on the IPv6 transition.

… we may expect to see a push to re-architect content into Content Distribution Networks that have points of presence in major access networks.

Today, major content distribution networks (CDNs) like Akamai, Amazon Cloudfront, Limelight and Google each maintain thousands of servers close to the edges of the Internet. These servers cache popular content close to where the users are.

When many, many users in Qatar simultaneously try to access the same content, the load on Qtel’s NAT boxes could be dramatically reduced by putting the appropriate CDN’s caching servers within Qtel’s private address space. Then requests for popular content wouldn’t even go through the NAT, reducing total traffic and dramatically reducing the occasions when two users are going through the NAT to the same public IP address.

It’s not in line with the Internet’s original end-to-end design, but as IPv4 addresses get more expensive, we can expect to see more and more use of NAT and CDN servers moving into carriers' private address domains.

White spaces above 3 GHz

2011-09-14T15:52:17-04:00

Yesterday, I gave a pitch for more access, on a secondary use basis, to the vast swaths of spectrum above 3 GHz - spectrum that is largely unused in most locations most of the time. Then I gave an update on netBlazr and how we are using the existing license-exempt spectrum in the 5 GHz band (over 500 MHz in the US).

I'm sorry there's no audio, but here's the deck I used:

White spaces above 3 GHz and an application

View more presentations from Brough Turner

Wireless conferences in Austin Texas this week

2011-09-12T13:42:11-04:00

While the big event is Internet Telephony Expo, there are two other conferences and a startup pitch fest going on in Austin this week. I'm leaving in the early morning and will be speaking twice tomorrow afternoon and then pitching netBlazr on Wednesday afternoon.

Tomorrow at 2:30pm I'm appearing on a panel at 4G Wireless Evolution. The panel is entitled "Wireless Fixes Access with Redundancy." The other panelists are from Sprint and Wave2Wave. Sprint is using point-to-point wireless for backhaul from their cell sites since they can't get competitive access to the fiber backhaul that AT&T and Verizon have. Wave2Wave is wireless Internet Service Procider. As netBlazr's approach is rather different, in both our business model and our use of fixed wireless technology, this should be an interesting panel.

Then at 3:30pm I'm the sole speaker for a session in the Super WiFi Summit just down the hall. The description is:

White Spaces: The Radio Evolution

Tuesday - 09/13/11 • 3:30-4:15pm

Brough Turner , Founder , netBlazr.com

Smart antennas and smart radios, Cognitive Radio and Beam Forming are on the verge of being incorporated into product. As we head toward these technologies, the opportunities exist for new models of service sharing and interconnection to deliver broadband solutions.

My talk will be a mix of what's possible today, what will become possible with next generation silicon and how netBlazr is using today's and tomorrow's technology to do an end run around the existing broadband market. Of particular interest is where additional white spaces would be useful - hint it's not just in the TV bands.

Finally, there's Startup Camp on Wednesday afternoon and early evening. netBlazr is one of five new companies choosen to present and I'll be doing the honors. Bob Metcalfe is the keynote speaker and there will be a panel of judges to provide critiques on the startups' pitches.

YouTube video flow control actually causes packet loss (and retransmission)

2011-07-24T18:17:08-04:00

There's an interesting article in the April 2011 issue of ACM SIGCOM Computer Communications Review. The study by Shane Alcock and Richard Nelson (also accessible here) looks at the way application level algorithms on YouTube's video servers interact with TCP and the actual buffers in a retail DSL delivery system. I found this particularly interesting as I had already looked into the burstiness of other kinds of traffic in a set of posts in late 2009 (this post in particular).

Here's the way YouTube servers deliver data (at least as of January 2010) to high capacity clients:

By high capacity client I mean the client device has enough buffer space to absorb whatever data the video server wants to send and the client's broadband Internet access service has enough capacity to avoid congestion during delivery of these video bursts. Unfortunately, the delivery rate YouTube was using in January 2010 was enough to overwhelm the data buffers in typical DSL infrastructure as this graph illustrates.

It appears the YouTube servers send data in blocks of 64 KBytes or 128 KBytes (or multiples thereof) and these blocks can exceed the available buffer space in the DSL delivery infrastructure - mostly likely the buffers in Broadband Remote Access Server (BRAS). At least one BRAS I was familiar with in 2004-2005 had 200 ms of buffering, obviously not enough for one burst per second.

The good news is the net effect was only a 1% increase in the total data (due to retransmission) so this isn't a big problem and the authors discussed the issue with Google where engineers were working on a solution (in 2010). What's interesting to me is the extent to which the sizing of buffers for IP infrastructure is still a complex issue and the ease with which a simple application level decision can go wrong.

3D On-Line Interactive Travel Planning

2011-07-15T11:52:57-04:00

I routinely use Google Maps to check out building-to-building wireless shots, either directly or via Ubiquiti's AirLink. I also have followed (in a low key sort of way) various 3D interactive simulations like Edushi (roughly "E-City") which covers many cities in China. There are more pointers in this blog post of a few years ago.

Now a friend, Terence Mak, is going after the vacation planning market directly with a new company "3rd Planet." They're not on the air yet, but they're working on their first project, Road to Everest, which will allow you to cover the trekking route to Everest basecamp, hopefully later this year. Meanwhile, there's an article here: http://www.huffingtonpost.com/karen-rubin/travel-planning-goes-3d-3_b_888538.html

Definitely something I want!

Freemium applied to wireless networks

2011-07-12T16:01:31-04:00

Recently, netBlazr got an inquiry from someone who had seen this video.

It's the talk I gave at the International Summit for Community Wireless Networks (#IS4CWN) in Vienna last August. I put my slides up on Slideshare even before I returned from Vienna but I didn't realize the conference organizers had put the videos up (apparently this happened in March).

eComm 2011

2011-06-27T12:07:26-04:00

I'm at eComm 2011 in California for the next three days (#eComm). eComm is one of the best events I attend for the content and for the people who are there.

I'll be speaking tomorrow afternoon, basically giving an update on netBlazr. Meanwhile, I'll be keeping my notes using my personal Twitter account (@brough).

Comparative broadband speeds - US loses again

2011-06-21T14:19:50-04:00

Recently Google Labs added the Ookla Speedtest data set to their wonderful Public Data Explorer so I just had to try it out.

Here's my first graph:

These are not bogus statistics. These graphs show the average of all the millions of actual speedtests run in the respective countries over the past 4 months.

The apologists for the US's poor showing usually start by pointing out that the US has much lower population density than South Korea, Sweden or Bulgaria. Of course that doesn't hold water if you compare Seoul, Stockholm and Sofia to New York, Los Angeles or Chicago. In Seoul, Stockholm and Sofia consumers can get 100/100 Mbps Internet access at affordable prices (e.g. $13/month in Stockholm) while such service isn't even offered to consumers in New York, Los Angeles or Chicago.

Attending Nantucket Conference

2011-06-09T15:31:47-04:00

I attended the Nantucket Conference ( #ack2011 ) for the first time last year and found it well worth it - partly to increase my local network here in New England (versus all my many friends in other parts of the world); but also for specific case studies that held lessons for me and for netBlazr. I'm here again this year and the program has just kicked off with three game company CEOs talking about what's up in their space.

Mostly I expect to be taking notes in the form of Tweets (@brough) so follow me there if you are interested.

netBlazr a finalist in MassChallege 2011

2011-05-24T17:43:11-04:00

Thanks to all who voted for us, endorsed us and otherwise helped netBlazr become a finalist in the MassChallenge 2011 startup contest and thus eligible to participate in their 2011 accelerator program.

By the way, we're also a finalist for the MITX innovation awards in the "Best Bootstrapped Startup" category.

Please vote for netBlazr at MassChallenge

2011-04-27T16:05:43-04:00

netBlazr benefitted from last year’s MassChallenge startup contest even thought we were only a few weeks old when we entered. We’ve come a long way in the past 11 months. If you haven't been following, we're trying to change the face of broadband access in US cities (more info here).

netBlazr has entered the MassChallenge 2011 Startup Contest and we’d like to solicite your endorsement of our entry.

It’s easy to vote:

1. Register at https://masschallenge.org/user/register You need to provide an email addresss and pick a “role.” But if you specify your role as “Observer/Supporter” you can avoid filing out any other forms.

2. You’ll receive an email from MassChallenge. Click on the link in this email to validate your registration.

3. Go to http://masschallenge.org/profile/team/netblazr and check out our profile.

4. Float your cursor over the “Votes” area in the upper right, then click on five stars.

That’s all there is to it. Thank you!

Paid Peering: Issues and misunderstandings

2011-04-26T10:01:07-04:00

Recently I was asked my opinion of Google paying France Telecom (FT) to deliver traffic to into FT's network, i.e. Google paying to peer with FT. I wasn't aware Google pays FT. I don't even know if it's true. But I do know this is a topic fraught with misunderstandings. Also, if there is a "problem" here, the problem is one of competition (or lack thereof) in portions of the French broadband access market. It is not a problem that can be or should be fixed by "network neutrality" regulations or legislation.

To understand what's happening, you need to understand the Internet's business model and you need to know something about peering as it works in the real world.

The most suscinct definition of the Internet I'm aware of is:
Internet (n.) A voluntary agreement among network operators to exchange traffic for their mutual benefit.

This is very different from the telephone networks (fixed or mobile) where relations between operators are governed by laws and regulations, change at a regulatory pace, i.e. decades, and are continuously gamed by political processes.

Each Internet operator needs to be able to reach all possible Internet addresses, so interconnection is essential. If you are a small operator, like netBlazr, you purchase "Internet transit" services from a larger operator. Rates are volume dependent and arrangements are similar to those of any other business or individual purchasing an Internet access service. If you are a large operator, a large content provider or a very large business, then interconnection costs and arrangements become negotiable. Two operators in Holland will likely agree to exchange that portion of their respective traffic that is destined for each other's networks at the AMS-IX which is local, rather than pay for Internet transit services that would likely carry that traffic to London or the US where a higher tier operator would handle the exchange. Thus the two Dutch operators engage in peering for that portion of their traffic for which it makes sense.

This pattern is repeated throughout the Internet as each operator evaluates where, how, and with whom it makes sense to exchange portions of their traffic so as to minimize costs, increase performance or achieve other goals important to that operator. Thus there are vastly more interconnection contracts, formed under more diverse terms, for the Internet than ever was the case for the telephone network. Further, this network of agreements is in constant flux as individual operators find better deals.

It's instructive to follow the growth of YouTube from their founding through their acquisition by Google. When YouTube began, they had to pay standard rates for Internet access. As they grew to be a significant content source, their cost of Internet access fell as more and more operators asked to peer with them, as I discussed two years ago.

So between Google and France Telecom, who has negotiating leverage? and why?

France Telecom already has peering agreements with multiple other Internet backbones, so their customers have several paths to get to Google content. Why would either party want to connect directly?

First, it might cut costs. Whatever pre-agreement path the traffic takes involves some cost. Perhaps that's money paid to other operators or it may just be the cost of maintaining the facilities needed for the pre-agreement traffic (e.g. to go via London). I can't guess the specifics for Google or for France Telecom, but each has a possible interest here.

Second, it will likely improve performance. Even shaving 50 milliseconds off of round trip times (RTT) can improve user experience as accessing a single web page can require the exchange of dozens of messages, thus 50 ms less RTT can shave more than a second off the page load time. In a competitive market, France Telecom might want to advertise their network as the "fastest," but local access competition is not that great in France (or in many markets, like the US). France Telecom has nearly 50% market share. They are losing ground to Free, but apparently it's not enough to justify a marketing campaign based on the "fastest" network. Google on the other hand, has a strong reason to want better user experiences. In Google experiments with search latency, longer latencies reduce the number of searches a user does per day. Given the number of Google search users on the France Telecom network, Google can directly compute their monetary return from cutting search latency by X ms. So Google's negotiators have hard numbers in their back pocket when they go to talk with France Telecom.

Is this good or bad? Well, if France Telecom doesn't have to compete on the performance of their service, that suggests a failure of competition policy. But then a solution should address competition in the French Internet access market, not government regulation of peering or the imposition of "network neutrality" regulations on operators that don't have a monopoly position.

For myself, I look forward to continued growth of new providers in France, like Free, as I discussed in the January issue of NGN Magazine.

Paul Baran and open spectrum

2011-03-28T09:28:13-04:00

Paul Baran, an engineer who helped create the technical underpinnings for the Arpanet (the precursor to today’s Internet), died Saturday in Palo Alto, California. While everyone else celebrates his early contributions to packet networking, I will remember him for his open spectrum advocacy.

I never had the privilege of hearing Paul Baran speak live, but as I became interested in wireless spectrum, one of the earliest references I encountered was this transcript of Paul Baran's Keynote Address at the 8th Annual Conference on Next Generation Networks Washington, DC, November 9, 1994.

His title says it all:

Visions of the 21st Century Communications: Is the Shortage of Radio Spectrum for Broadband Networks of the Future a Self Made Problem?

And here's an excerpt:

   The key point at issue that we will question is the widespread belief
   that we don't have enough radio spectrum to go around. This is a
   common, fundamental belief. Since we live in a world of scarcity or
   natural resources it is almost automatic that we believe that there is
   a shortage of frequencies. This particular resource is somewhat
   different.
   
   This morning, let's start by reviewing this presumption of a permanent
   shortage. Let's consider how, with an application of already known
   technology, we could create even a surplus of frequencies. What may be
   going on is an inadvertent shortage created by a regulatory structure
   which has yet to appreciate the potential capabilities of the new
   digital signal processing technology as applied to communications.

Paul Baran is hardly the originator of open spectrum ideas, but the complete transcript shows he once again led the industry.

Mobile oligopoly tightens

2011-03-20T15:33:41-04:00

I remember the heady days of the late 90s (while the PCS build out was happening). Depending on how and when you counted, we had more than 6 mobile operators in the Boston area. Everyone was competing for customers, to the great benefit of the consumer, as mobile phones rapidly transitioned from expensive car phones to relatively low cost, widely adopted personal handheld devices.

In recent years we've seen that competition shrink to just four operators (Verizon, AT&T, Sprint and T-Mobile). At one time, I was hopeful that Clearwire would be one more operator, but then they became effectively joined to Sprint. More recently I've been hopeful about Lightsquared, although they are a long way from providing service.

Now we get bad news. AT&T is buying T-Mobile. Consolidation! Less competition not more. Ugh!

Basic questions about NGNs

2011-03-07T09:24:02-05:00

I get questions on telecom, mobile and Internet topics from students in different parts of the world and I try to reply to them all as best I can. One kind of question that comes up repeatedly has to do with "Next Generation Networks" or NGNs - what are they? why are they based on packet technology? how do they support multi-services? etc.

Recently I answered a whole string of such questions for a Masters student in the UK. Here are my answers:

Hi ... ,

For most kinds of communication, packet networks are more flexible and more efficient. And, as a practical matter, the Internet (a packet network) has become a globally pervasive platform, which indeed can be used to support almost any kind of communication. Most everything is migrating to the Internet because the Internet is pervasive and Internet technology is by far the highest volume and lowest cost of any communications technology. So it's natural that any envisioned NGN would be built on packet technology.

The term NGN is a bit loaded, as it normally refers to a telco-centric view of how the Internet should evolve. My views on that are here:

http://www.tmcnet.com/ngnmag/columns/articles/126646-ngn-itu-misses-boat.htm

For the latest on how many AS numbers have been assigned see:

http://www.cidr-report.org/as2.0/autnums.html

For the latest on how many AS numbers are currently advertising routes on the Internet backbone, see:

http://www.cidr-report.org/as2.0/

The only issue with carrying a variety of services over a common platform is whether you need different relative levels of service (QoS) to support different higher level services like telephony, video, web browsing, etc. The telco view is that a sophisticated range of priorities are essential (and that the telco should be able to differentially bill based on the higher level service that is being carried). However, no one has figured out a commercially viable way to deliver QoS over the public Internet. Also, if there is any requirement for QoS at all, it is for very simple differentiation at just those few points where there are bandwidth shortages.

The richest set of details on what an NGN is envisioned to be is presented in the standards of the 3GPP (the body that provides standards for GSM, HSPA, LTE and other wireless networks). See:

http://en.wikipedia.org/wiki/IP_Multimedia_Subsystem

http://en.wikipedia.org/wiki/System_Architecture_Evolution

and if you want to read the actual 3GPP specs, you might start here:

http://www.3gpp.org/ftp/Specs/archive/23_series/23.402/23402-a21.zip

You'll have to dig through documentation on the 3GPP's IMS and SAE if you want to understand their plans for their NGN. I don't expect any NGN to gain much traction compared to the open Internet and I personally have moved from a business where I supplied products to telco equipment vendors into a new business, netBlazr, where we are revolutionizing the delivery of fixed Internet connectivity in urban areas. So I'm not so interested in NGN any more. :)

MPLS is an IP-centric protocol layer just below the IP layer which allows Internet Service Providers with multiple routes to define "virtual circuits" between points in the core network. It's a way to hide (i.e. simplify) an otherwise complex network of IP routers and to channel certain kinds of traffic over specific virtual circuits. This can be used to guarantee enough headroom for certain kinds of traffic and for other network management purposes. For example, if you want to give priority to voice traffic, you could route all voice-related IP sessions over a different path (different at the MPLS level) and you could guarantee enough bandwidth on that path so voice traffic was never over-subscribed (i.e. never ran out of bandwidth). When there was little or no voice traffic, other MPLS virtual circuits running over the same links could use the idle bandwidth, but when voice traffic increases, the voice circuit would get it's predetermined bandwidth.

Indeed, MPLS works by assigning labels (which are inserted between the link layer protocol header and the IP header). Here's a view of how MPLS & QoS are envisioned to work:

http://www.huawei.com/products/datacomm/catalog.do?id=2515

This is simpler than the ITU/3GPP view of NGN, but still likely more complex than what most network operators are deploying. On the other hand, I don't have direct field experience operating a backbone network, so i can't give you the real details. My impression is that Internet backbone operators use MPLS but only for very simple pre-defined bandwidth allocations between major backbone routers.

I hope this helps,

Brough Turner

My Column has moved to NGN Magazine

2011-02-10T11:38:13-05:00

"Next Wave Redux," which has appeared in Internet Telephony magazine for many years has moved. I'm now writing for NGN Magazine.

With my attention focused on netBlazr, I wasn't in a position to do justice to Internet telephony topics. I thought of abandonning the column entirely, but the folks at TMCnet urged me to move to a different magazine, more in line with my current focus. Of course, the term NGN carries a lot of baggage which I address in my first article, NGN: ITU Misses the Boat, written last fall for the November 2010 issue.

If you followed by columns in Internet Telephony, you may want to sign up for electronic delivery of NGN magazine (i.e. via email), as the issues typically don't appear on the TMC website until a couple of months later.

Extending white spaces rules to other under-utilized spectrum

2011-02-04T08:22:45-05:00

Few seem to have noticed, but the FCC has an open Notice of Inquiry in which, among other things, they say,

48. ... An alternative approach for enabling dynamic spectrum use is to extend the concepts underlying the rules for Television Band Devices to additional spectrum bands. ... Commenters should address whether they believe this concept is practical for other bands. If so, they should identify in which bands they believe such a system could work and provide details on how it would work.

Wow!

This is action on Recommendation 5.13 in Section 5.6 of the FCC's National Broadband Plan. While I'm generally disappointed with the National Broadband Plan, this is one place where there's a (perhaps remote) possibility for real long term progress.

As I've commented in the past, the largest value of the TV White Spaces ruling is that it provides a path for opening up more of our incredibly under-utilized spectrum. This NOI is the first step. Comments are due by February 28, 2011 and reply comments by March 28, 2011. Directions and links are available on this Federal Register page.

Super Wi-Fi Summit, 4G Wireless Evolution and IT Expo

2011-02-03T16:12:06-05:00

I’m in the midst of multiple co-located conferences, Super Wi-Fi Summit, 4G Wireless Evolution, IT Expo, all conveniently located in Miami, although I barely got here on Tuesday just ahead of a major storm in Boston.

At the Super Wi-Fi Summit, I gave a presentation about netBlazr. This conference is focused on technologies for use in the newly available TV White Spaces spectrum, particularly Wi-Fi (802.11af). I told Carl Ford (the conference organizer) that netBlazr was using 5 GHz 802.11n, not TVWS, but he still wanted me to present the netBlazr story.

Disruptive broadband

View more presentations from Brough Turner.

Then, in the 4G Wireless Evolution Conference, Carl had asked me to give some perspective on when Over-the-Top applications will conquer all. With all my attention focused on netBlazr, that was a little off topic, but I have views and opinions which I put together in this presentation.

Why Over-the-Top is the Future of Communications

View more presentations from Brough Turner.

Aside from my two presentations, I’ve met a lot of old friends and met several useful contacts for the future. I’ve also met a number of wireless ISPs, both through the Super Wi-Fi Summit and through the WISPA booth on the show floor. All in all, well worth the trip!

Cable trounces the telcos

2011-01-28T16:07:37-05:00

Yesterday, Netflix posted graphs of how well various ISPs deal with Netflix video streams. The results are striking.

All the cable companies easily beat all the phone companies with the exception of Verizon where we're seeing a mix of DSL and FiOS results.

And just in case you believed the hype about 4G, notice that Clearwire's Clear service comes in below DSL. There is no reason to believe LTE networks will do any better once they have customers, i.e. once they are carrying commercially viable levels of traffic.