Requiring receiver vendors to represent to buyers that their equipment is fit for purpose is a way to avoid cheap receivers from reducing the performance of coexisting systems in the “decoupled receiver” case, i.e. when there isn't a license holder to negotiate with.
Showing posts with label wireless. Show all posts
Showing posts with label wireless. Show all posts
Sunday, January 01, 2012
Friday, September 02, 2011
TV white space databases: A bad idea for developing countries
Now that TV white space rulemakings are in the can in the US and UK, proponents will be pitching the technology to any government that’ll listen, e.g. at the Internet Governance Forum meeting to be held in Nairobi on 27-30 September.
It’s understandable: the more widespread white space database rules, the larger device volumes will be, and thus the lower the equipment cost, leading to wider adoption – a positive feedback loop. However, white space database technology is unnecessary in many countries, particularly developing ones.
Yet it verges on dodgy ethics for companies to hype this technology to countries that don’t need it, particularly since there’s a better solution: dedicating part of the TV frequencies that are freed as a result of the transition to digital TV (the “Digital Dividend”) to unlicensed operation, without the white space bells and whistles.
It’s understandable: the more widespread white space database rules, the larger device volumes will be, and thus the lower the equipment cost, leading to wider adoption – a positive feedback loop. However, white space database technology is unnecessary in many countries, particularly developing ones.
Yet it verges on dodgy ethics for companies to hype this technology to countries that don’t need it, particularly since there’s a better solution: dedicating part of the TV frequencies that are freed as a result of the transition to digital TV (the “Digital Dividend”) to unlicensed operation, without the white space bells and whistles.
Tuesday, August 23, 2011
Time limiting unlicensed authorizations
One could get around the problem and still have unlicensed use, though, by time limiting the unlicensed authorization. [1] Just like build-out conditions on licenses, there would be a fixed time window within which widespread deployment should occur. If it doesn’t, the authorization is revoked.
This approach seems particularly relevant when an authorization holds great promise, but that promise is very uncertain, e.g. when the technology or the market is changing rapidly. “Sunsets” on rules are important since the passage of time invariably invalidates the premises of regulation, even as it entrenches the interests that coalesce around those regulations. [2]
Wednesday, August 17, 2011
Licensing radio receivers as a way to facilitate negotiation about interference
It’s a curious fact that, while receivers are just as much responsible for breakdowns in radio operations as transmitters [a], regulation is aimed pretty much exclusively at transmitters [b].
Since one can’t ignore the receivers in practice, arguments over interference almost invariably turn to receiver standards. Even if receiver standards were a good idea (and I don’t think they are - see my post Receiver protection limits: a better way to manage interference than receiver standards), the ability to adjust receiver performance by fiat or negotiation is limited when receivers are operated independently of transmitters.
I suspect that receiver licenses may be necessary to reach the optimum outcome in at least some cases. This post is going to take that idea out for a first test drive.
Regulators evidently have managed without receiver licenses (beyond their use as a way to fund traditional broadcasting) so far. Why introduce them now? I’ll give my usual answer: the dramatically increased demand for wireless is squeezing radio operators of widely varying kinds together to an unprecedented extent, and we no longer have the luxury of the wide gaps that allowed regulators to ignore receiver performance, and ways of managing it.
Follow-up post
Since one can’t ignore the receivers in practice, arguments over interference almost invariably turn to receiver standards. Even if receiver standards were a good idea (and I don’t think they are - see my post Receiver protection limits: a better way to manage interference than receiver standards), the ability to adjust receiver performance by fiat or negotiation is limited when receivers are operated independently of transmitters.
I suspect that receiver licenses may be necessary to reach the optimum outcome in at least some cases. This post is going to take that idea out for a first test drive.
Regulators evidently have managed without receiver licenses (beyond their use as a way to fund traditional broadcasting) so far. Why introduce them now? I’ll give my usual answer: the dramatically increased demand for wireless is squeezing radio operators of widely varying kinds together to an unprecedented extent, and we no longer have the luxury of the wide gaps that allowed regulators to ignore receiver performance, and ways of managing it.
Follow-up post
Tuesday, August 09, 2011
The dark side of whitespace databases
Back in May 2009 I drafted a blog about the unintended side-effects of regulating unlicensed radios using databases. I was in the thick of TV whitespace proceeding (on the side of the proponents), and decided not to post it since it might have muddied the waters for my client.
Databases have become the Great White Hope of “dynamic spectrum access” over the last two-plus years. They are seen not only as a way to compensate for the weaknesses of “spectrum sensing” solutions, but as a way for regulators to change the rules quickly, and for unlicensed devices to work together more efficiently. For a quick background, see: FCC names nine white-space database providers, FierceWireless, Jan 2011; Michael Calabrese, “Ending Spectrum Scarcity: Building on the TV Bands Database to Access Unused Public Airwaves,” New America Foundation, Wireless Future Working Paper #25 (June 2009).
Looking back at my note, I think it's still valid. Rather than rewrite it, I’ve decided simply to repost it here as originally drafted (omitting a couple of introductory paragraphs).
Databases have become the Great White Hope of “dynamic spectrum access” over the last two-plus years. They are seen not only as a way to compensate for the weaknesses of “spectrum sensing” solutions, but as a way for regulators to change the rules quickly, and for unlicensed devices to work together more efficiently. For a quick background, see: FCC names nine white-space database providers, FierceWireless, Jan 2011; Michael Calabrese, “Ending Spectrum Scarcity: Building on the TV Bands Database to Access Unused Public Airwaves,” New America Foundation, Wireless Future Working Paper #25 (June 2009).
Looking back at my note, I think it's still valid. Rather than rewrite it, I’ve decided simply to repost it here as originally drafted (omitting a couple of introductory paragraphs).
Tuesday, April 19, 2011
Too strategic to be true?
The cellular industry has been very vocal in calling on the FCC to allocate more spectrum licenses to satisfy the forecast demand for mobile data services. For two examples more or less at random, see this CTIA white paper, and the 4G Americas white paper “Sustaining the Mobile Miracle” (PDF).
On reflection, though, it strikes me as rather curious behavior for cut-throat competitors. More spectrum licenses won’t satisfy the insatiable demand for wireless data capacity any more than building highways reduces traffic congestion, and while it might make strategic sense, in the short term – and isn’t that all that really matters for listed companies, when all the rhetoric is said and done? – it means that the cellcos are giving up a wonderful opportunity to make money.
If the supply of spectrum licenses were fixed, and not increased by reallocation of other services to mobile wireless, then Economics 101 dictates that the price for wireless data would rise. (This is ignored in the forecasts; see e.g. my post Cisco’s Fascinating Flaky Forecast.) Operators wouldn’t incur the capital costs of lighting up new frequencies, and so their profits would rise – a lot!
On the other hand, if more cellular licenses were made available, the carriers would not only have to buy them at auction, but they would have to buy and install the infrastructure to use them. The price they could charge for wireless data service wouldn’t change much, and so their profits would go down, or at best stay flat.
All that said, though: these companies are much, much smarter business people than I am. I must be missing something. But what?
Perhaps this is all just a big CYA operation. When the inevitable demand crunch happens (with or without new cellular licenses, demand is set to outstrip supply), the operators will be able to blame the government: “Dear customer, it’s not our fault, we’ve been asking the government to help us give you the services you want, but they didn’t come through. We’re sorry, but all we can do to make sure that those who really need wireless services get them is to increase prices.”
On reflection, though, it strikes me as rather curious behavior for cut-throat competitors. More spectrum licenses won’t satisfy the insatiable demand for wireless data capacity any more than building highways reduces traffic congestion, and while it might make strategic sense, in the short term – and isn’t that all that really matters for listed companies, when all the rhetoric is said and done? – it means that the cellcos are giving up a wonderful opportunity to make money.
If the supply of spectrum licenses were fixed, and not increased by reallocation of other services to mobile wireless, then Economics 101 dictates that the price for wireless data would rise. (This is ignored in the forecasts; see e.g. my post Cisco’s Fascinating Flaky Forecast.) Operators wouldn’t incur the capital costs of lighting up new frequencies, and so their profits would rise – a lot!
On the other hand, if more cellular licenses were made available, the carriers would not only have to buy them at auction, but they would have to buy and install the infrastructure to use them. The price they could charge for wireless data service wouldn’t change much, and so their profits would go down, or at best stay flat.
All that said, though: these companies are much, much smarter business people than I am. I must be missing something. But what?
Perhaps this is all just a big CYA operation. When the inevitable demand crunch happens (with or without new cellular licenses, demand is set to outstrip supply), the operators will be able to blame the government: “Dear customer, it’s not our fault, we’ve been asking the government to help us give you the services you want, but they didn’t come through. We’re sorry, but all we can do to make sure that those who really need wireless services get them is to increase prices.”
Tuesday, March 01, 2011
“Quiet” doesn’t mean “unused”: The Downside of Under-defined Radio Rights
The FCC has promised to find and reallocate 500 MHz of radio frequencies to satisfy the burgeoning demand for high bandwidth mobile services such as video on cell phones. The idea, the hope, is that there are lots of unused bands to be repurposed. “Unused” is a tricky notion, though. I’ll take it to mean “radio quiet”: a radio energy detector doesn’t observe much if anything at certain frequencies, and the assumption is that a new service could transmit here.
Of course, nothing is as simple as that. Let’s assume that the services that actually operate in these quiet bands – and there are always incumbents, since every frequency has one if not many nominal users – can be found a new home, and that they’ll relocate. The harder problem is that a quiet band may not in fact be usable because of the equipment in neighboring bands. The LightSquared/GPS argument is a conveniently current example. The proposal to allow LightSquared to deploy lots of ground-based transmitters in a band where to date only satellite transmissions were allowed has caused shock and outrage among GPS users who claim that their receivers cannot distinguish between the LightSquared signal in the adjacent band and the satellite location signals in the GPS channel.
Since the FCC’s rules and precedents provide almost unlimited protection against "harmful interference" (a notoriously vague term) caused by new services, an incumbent is pretty much assured that it will be held harmless against any change. The situation is exacerbated because FCC licenses only specify transmission parameters and say nothing about the radio interference environment that receivers should be able to cope with. Radio receivers are thus designed and built as if their radio environment will never change; if a band has been quiet, none of the receivers in the adjacent frequencies can cope with more intensive use, since building in that protection costs money. (For complementary perspectives on this problem, and suggested remedies, see two short papers presented at a recent conference in Washington, DC: Kwerel and Williams, De Vries and Sieh.)
Thus, just because a band is quiet doesn’t mean that it’s unoccupied; it’s probably effectively occupied by the protection afforded to the cheap receivers next door that haven’t been required to, and therefore don’t, tolerate any substantial operation in the quiet channel. It’s as if the incumbent were a householder whose property used to be passed by track along which only ox wagons passed. She didn’t have to take any precaution against her dogs being run over by a wagon, such as building a fence, and this unlimited protection still holds even when the track is turned into an arterial road, holding passing vehicles completely responsible if a dog is run over.
Money could, but might not, solve the problem. Let’s say Tom Transmitter wants to deploy a new service
in the formerly quiet band, and that this would cost the incumbent neighbor, Rae Receiver, $300 million, either in lost revenue from diminished service and/or because of precautions such as new receiver filters that are needed to reject Tom’s adjacent band signals. If the benefit to Tom is big enough, if for example he could generate $500 million in profit, Tom could compensate Rae and still come out ahead. But how is the $200 million of potential gain ($500 million - $300 million) to be divided? This depends on Rae’s rights. If she has the right to prevent any operation by Tom (i.e. she can take out an injunction against him), she can demand essentially all his profits as a condition of operationlet’s say $499 million of his $500 million, whereas if she’s entitled to damages, she can only demand $300 million for actual losses. These are very different outcomes. Under an injunction, Tom’s incremental net profit is $1 million ($500 million - $499 million) and Rae’s is $199 million ($499 million - $300 million), whereas under damages, Tom’s net profit is $200 million and Rae’s is zero.
However, since the FCC doesn’t specify whether licenses are protected by damages or injunctions, Tom and Rae can’t begin to deal, since the legal basis of the negotiation is unclear. Tom will hope that he can get the whole $200 million incremental gain, and Rae will hope for it, too – a huge difference in expectations that will almost inevitably prevent the parties from coming to an agreement.
(There are further obstacles to reaching a settlement that I won’t go into here, such as uncertainty over what action by Tom actually constitutes damage to Rae due to ambiguity in the way FCC rules are currently formulated, and the freeloader/hold-out problems with negotiations involving many parties.)
What's to be done?
1. Any inventory of “unused” radio capacity should not only itemize radio quiet bands, but also the nature of the service and receivers next door, so that the cost of relocating, protecting or degrading the incumbent service can be estimated.
2. Any new licenses that are issued should specify whether they’re protected by injunctions or damages; this will facilitate negotiation.
3. Any new license should specify the receiver protection parameters the operator can rely on, and by implication what will not be protected.
4. Regulators should start retrofitting existing licenses to this new approach by specifying the remedy (#2) and laying out a timeline over which receiver protections (#3) will be dialed down from the current open-ended “no harmful interference” condition to more realistic and objective received energy levels.
The two page position paper I referenced above gives a quick introduction to these measures; for all the gory details, see the 15 page long version on SSRN.
Of course, nothing is as simple as that. Let’s assume that the services that actually operate in these quiet bands – and there are always incumbents, since every frequency has one if not many nominal users – can be found a new home, and that they’ll relocate. The harder problem is that a quiet band may not in fact be usable because of the equipment in neighboring bands. The LightSquared/GPS argument is a conveniently current example. The proposal to allow LightSquared to deploy lots of ground-based transmitters in a band where to date only satellite transmissions were allowed has caused shock and outrage among GPS users who claim that their receivers cannot distinguish between the LightSquared signal in the adjacent band and the satellite location signals in the GPS channel.
Since the FCC’s rules and precedents provide almost unlimited protection against "harmful interference" (a notoriously vague term) caused by new services, an incumbent is pretty much assured that it will be held harmless against any change. The situation is exacerbated because FCC licenses only specify transmission parameters and say nothing about the radio interference environment that receivers should be able to cope with. Radio receivers are thus designed and built as if their radio environment will never change; if a band has been quiet, none of the receivers in the adjacent frequencies can cope with more intensive use, since building in that protection costs money. (For complementary perspectives on this problem, and suggested remedies, see two short papers presented at a recent conference in Washington, DC: Kwerel and Williams, De Vries and Sieh.)
Thus, just because a band is quiet doesn’t mean that it’s unoccupied; it’s probably effectively occupied by the protection afforded to the cheap receivers next door that haven’t been required to, and therefore don’t, tolerate any substantial operation in the quiet channel. It’s as if the incumbent were a householder whose property used to be passed by track along which only ox wagons passed. She didn’t have to take any precaution against her dogs being run over by a wagon, such as building a fence, and this unlimited protection still holds even when the track is turned into an arterial road, holding passing vehicles completely responsible if a dog is run over.
Money could, but might not, solve the problem. Let’s say Tom Transmitter wants to deploy a new service
in the formerly quiet band, and that this would cost the incumbent neighbor, Rae Receiver, $300 million, either in lost revenue from diminished service and/or because of precautions such as new receiver filters that are needed to reject Tom’s adjacent band signals. If the benefit to Tom is big enough, if for example he could generate $500 million in profit, Tom could compensate Rae and still come out ahead. But how is the $200 million of potential gain ($500 million - $300 million) to be divided? This depends on Rae’s rights. If she has the right to prevent any operation by Tom (i.e. she can take out an injunction against him), she can demand essentially all his profits as a condition of operationlet’s say $499 million of his $500 million, whereas if she’s entitled to damages, she can only demand $300 million for actual losses. These are very different outcomes. Under an injunction, Tom’s incremental net profit is $1 million ($500 million - $499 million) and Rae’s is $199 million ($499 million - $300 million), whereas under damages, Tom’s net profit is $200 million and Rae’s is zero.
However, since the FCC doesn’t specify whether licenses are protected by damages or injunctions, Tom and Rae can’t begin to deal, since the legal basis of the negotiation is unclear. Tom will hope that he can get the whole $200 million incremental gain, and Rae will hope for it, too – a huge difference in expectations that will almost inevitably prevent the parties from coming to an agreement.
(There are further obstacles to reaching a settlement that I won’t go into here, such as uncertainty over what action by Tom actually constitutes damage to Rae due to ambiguity in the way FCC rules are currently formulated, and the freeloader/hold-out problems with negotiations involving many parties.)
What's to be done?
1. Any inventory of “unused” radio capacity should not only itemize radio quiet bands, but also the nature of the service and receivers next door, so that the cost of relocating, protecting or degrading the incumbent service can be estimated.
2. Any new licenses that are issued should specify whether they’re protected by injunctions or damages; this will facilitate negotiation.
3. Any new license should specify the receiver protection parameters the operator can rely on, and by implication what will not be protected.
4. Regulators should start retrofitting existing licenses to this new approach by specifying the remedy (#2) and laying out a timeline over which receiver protections (#3) will be dialed down from the current open-ended “no harmful interference” condition to more realistic and objective received energy levels.
The two page position paper I referenced above gives a quick introduction to these measures; for all the gory details, see the 15 page long version on SSRN.
Monday, February 21, 2011
Juggling Pipes: orchestrating scarce radio resources to serve multifarious applications
I concluded in Cisco’s Fascinating Flaky Forecast that the impending supply/demand mismatch in wireless data services presents opportunities for “innovations that improve effective throughput and the user experience”. This post explains one example: a software layer that that matches up various applications on a device to the most appropriate connectivity option available, mixing and matching apps to pipes to make the cheapest, fastest, or most energy efficient connection. (In academic terms, it’s a version of Joe Mitola’s Cognitive Radio vision.)
Peter Haynes recently prompted me to ask some experts what they thought the most exciting wireless technology developments were likely to be in the next decade. Mostly the answer was More of The Same; a lot of work still has to be done to realize Mitola’s vision. The most striking response was from Milind Buddhikot at Bell Labs, who suggested that the wireless network as we know it today will disappear into a datacenter by 2020, which I take to mean that network elements will be virtualized.
I don’t know about the data center, but from a device perspective it reminded me of something that’s been clear for some time: as a device’s connectivity options keep growing, from a single wired network jack to include one or more cellular data connections, Wi-Fi, Bluetooth, UWB, ZigBee etc., as the diversity of applications and their needs keeps growing, from an email client to many apps with different needs including asynchronous downloads, voice and video streams, and data uploads, and as choosing among becomes more complicated, such as trade-offs between connectivity price, speed, quality of the connection, and energy usage, there is a growing need for a layer that sits between all these components and orchestrates all these connections. Can you say “multi-sided market”?
The operating system is the obvious place to do such trade-offs. It sits between applications and peripherals, and already provides apps with abstractions of network connectivity. As far as I know, no OS provider has stepped up with a road map “smart connectivity.” It’s decidedly not just “smart radio” as we’ve heard about with “white spaces”; the white space radio is just one of the many resources that need to be coordinated.
For example, one Wi-Fi card should be virtualized as multiple pipes, one for every app that wants to use it. Conversely, a Wi-Fi card and a 3G modem could be bonded into a single pipe should an application need additional burst capacity. And the OS should be able to swap out the physical connection associated with a logical pipe without the app having to know about it, e.g. when one walks out of a Wi-Fi hotspot and needs to switch to wide-area connectivity; the mobile phone companies are already doing this with Wi-Fi, though I don’t know how well it’s working.
That said, the natural winner in this area isn’t clear. Microsoft should be the front-runner given its installed base on laptops, its deep relationships with silicon vendors, and its experience virtualizing hardware for the benefit of applications – but it doesn’t seem interested in this kind of innovation.
Google has an existential need to make connectivity to its servers as good as it could possibly be, and the success of Android in smartphones gives it a platform for shipping client code, and credibility in writing an OS. However, it is still early in developing expertise in managing an ecosystem of hardware vendors and app developers.
The network operators don’t much end-user software expertise, but they won’t allow themselves to be commoditized without a fight, as they would be if a user’s software could choose moment-to-moment between AT&T and Verizon’s connectivity offers. The telcos have experience building and deploying connectivity management layers through orgs like 3GPP. Something like this could be built on IMS, but it’s currently a network rather than device architecture. And the network operators are unlikely to deploy software that allows the user to roam to another provider’s data pipes.
The chipset and handset vendors are in a weaker position since they compete amongst themselves so much for access to telcos. Qualcomm seems to get it, as evidenced by their Gobi vision, which is several years old now: “With Gobi, the notebook computer becomes the unifying agent between the different high speed wireless networking technologies deployed around the world and that means freedom from having to locate hotspots, more choice in carrier networks, and, ultimately, freedom to Gobi where you want without fear of losing connectivity – your lifeline to your world.” As far as I can tell, though, it doesn’t go much beyond hardware and an API for supporting multiple 3G/4G service providers on one laptop. Handset vendors like
Vendors like Samsung or HTC could make a go of it, but since network operators are very unlikely to pick a single hardware vendor, they will only be able to get an ecosystem up to scale if they collaborate in developing a standard. It’s more likely that they will line up behind the software giants when Google and/or Microsoft come forward with their solutions.
It is also possible that Cisco (or more likely, a start-up it acquires) will drive this functionality from the network layer, competing with or complementing app/pipe multiplexing software on individual devices. As Preston Marshall has outlined for cognitive radio,* future networks will adapt to user needs and organize themselves to respond to traffic flow and quality of service needs, using policy engines and cross-layer adaptation to manage multiple network structures. There is a perpetual tussle for control between the edge of the network and the center; smart communications modules will be just another installment.
* See Table 4 in Preston F Marshall, “Extending the Reach of Cognitive Radio,” Proceedings of the IEEE, vol. 97 no. 4 p. 612, April 2009
Peter Haynes recently prompted me to ask some experts what they thought the most exciting wireless technology developments were likely to be in the next decade. Mostly the answer was More of The Same; a lot of work still has to be done to realize Mitola’s vision. The most striking response was from Milind Buddhikot at Bell Labs, who suggested that the wireless network as we know it today will disappear into a datacenter by 2020, which I take to mean that network elements will be virtualized.
I don’t know about the data center, but from a device perspective it reminded me of something that’s been clear for some time: as a device’s connectivity options keep growing, from a single wired network jack to include one or more cellular data connections, Wi-Fi, Bluetooth, UWB, ZigBee etc., as the diversity of applications and their needs keeps growing, from an email client to many apps with different needs including asynchronous downloads, voice and video streams, and data uploads, and as choosing among becomes more complicated, such as trade-offs between connectivity price, speed, quality of the connection, and energy usage, there is a growing need for a layer that sits between all these components and orchestrates all these connections. Can you say “multi-sided market”?
The operating system is the obvious place to do such trade-offs. It sits between applications and peripherals, and already provides apps with abstractions of network connectivity. As far as I know, no OS provider has stepped up with a road map “smart connectivity.” It’s decidedly not just “smart radio” as we’ve heard about with “white spaces”; the white space radio is just one of the many resources that need to be coordinated.
For example, one Wi-Fi card should be virtualized as multiple pipes, one for every app that wants to use it. Conversely, a Wi-Fi card and a 3G modem could be bonded into a single pipe should an application need additional burst capacity. And the OS should be able to swap out the physical connection associated with a logical pipe without the app having to know about it, e.g. when one walks out of a Wi-Fi hotspot and needs to switch to wide-area connectivity; the mobile phone companies are already doing this with Wi-Fi, though I don’t know how well it’s working.
That said, the natural winner in this area isn’t clear. Microsoft should be the front-runner given its installed base on laptops, its deep relationships with silicon vendors, and its experience virtualizing hardware for the benefit of applications – but it doesn’t seem interested in this kind of innovation.
Google has an existential need to make connectivity to its servers as good as it could possibly be, and the success of Android in smartphones gives it a platform for shipping client code, and credibility in writing an OS. However, it is still early in developing expertise in managing an ecosystem of hardware vendors and app developers.
The network operators don’t much end-user software expertise, but they won’t allow themselves to be commoditized without a fight, as they would be if a user’s software could choose moment-to-moment between AT&T and Verizon’s connectivity offers. The telcos have experience building and deploying connectivity management layers through orgs like 3GPP. Something like this could be built on IMS, but it’s currently a network rather than device architecture. And the network operators are unlikely to deploy software that allows the user to roam to another provider’s data pipes.
The chipset and handset vendors are in a weaker position since they compete amongst themselves so much for access to telcos. Qualcomm seems to get it, as evidenced by their Gobi vision, which is several years old now: “With Gobi, the notebook computer becomes the unifying agent between the different high speed wireless networking technologies deployed around the world and that means freedom from having to locate hotspots, more choice in carrier networks, and, ultimately, freedom to Gobi where you want without fear of losing connectivity – your lifeline to your world.” As far as I can tell, though, it doesn’t go much beyond hardware and an API for supporting multiple 3G/4G service providers on one laptop. Handset vendors like
Vendors like Samsung or HTC could make a go of it, but since network operators are very unlikely to pick a single hardware vendor, they will only be able to get an ecosystem up to scale if they collaborate in developing a standard. It’s more likely that they will line up behind the software giants when Google and/or Microsoft come forward with their solutions.
It is also possible that Cisco (or more likely, a start-up it acquires) will drive this functionality from the network layer, competing with or complementing app/pipe multiplexing software on individual devices. As Preston Marshall has outlined for cognitive radio,* future networks will adapt to user needs and organize themselves to respond to traffic flow and quality of service needs, using policy engines and cross-layer adaptation to manage multiple network structures. There is a perpetual tussle for control between the edge of the network and the center; smart communications modules will be just another installment.
* See Table 4 in Preston F Marshall, “Extending the Reach of Cognitive Radio,” Proceedings of the IEEE, vol. 97 no. 4 p. 612, April 2009
Saturday, February 12, 2011
Cisco’s Fascinating Flaky Forecast
Ed Thomas prompted me to have a look at Cisco’s recently published Visual Networking Index: Global Mobile Data Traffic Forecast Update, 2010–2015.
The numbers are staggering: global mobile data traffic grew 2.6-fold in 2010, nearly tripling for the third year in a row; mobile video traffic will exceed 50% for the first time in 2011; and Cisco predicts that global mobile data traffic will increase 26-fold between 2010 and 2015. Big numbers forecast by someone who’ll make money if they come true are always suspect, though. While the historical data are largely indisputable – and amazing – I think the forecasts are bogus, though in interesting ways.
Flags went up at the projection of 92% CAGR in mobile traffic growth over the next five years. From the scant details on assumptions provided in the report, I suspect the overall growth is driven (more than driven, in fact) by the growth in the number of users, not by increases in per-user usage. For example, Cisco predicts that the number of mobile-only Internet users will grow 25-fold between 2010 and 2015 to reach 788 million, over half of them in “Asia Pacific” (defined to exclude Japan).
Working back from their forecast data volumes and assumptions on user growth, however, suggests that usage per user (I prefer to think in terms of Megabits/second rather than ExaBytes/month) doesn’t increase over the study period, an in fact declines.
The growth in traffic thus hinges on the global user base growing to almost 800 million mobile-only users in five years, from 14 million today. That’s staggering, and to me implausible.
If nothing else, though, this demonstrates that using Cisco’s meganumbers don’t necessarily imply an impending bandwidth crunch doesn’t hold water. It doesn’t mean there isn’t going to be one, just that growth numbers don’t imply/require it, because they’re in large part driven by hundreds of millions of new users in China.
A more fundamental flaw is that the analysis is entirely demand driven. This was probably fine when Cisco was predicting wireline use, since there is so much dark fiber that supply is essentially unlimited. However, one cannot ignore the scarcity of radio licenses. We’re near the Shannon limit of the number of bits/second that can be extracted from a Hertz of bandwidth, and massive new frequency allocations will not show up overnight. An alternative is to reduce cell size and serve more users per cell by using smart antennas; however, such a build-out will take time. I don’t know how much extra traffic one can fit into the existing infrastructure and frequencies, but Cisco should at least have made an argument that this doesn’t matter, or that it can ramp up as fast as the demand.
While there may be spare capacity in China, there’s clearly a supply question in markets that are already halfway up the growth curve, though, like the US. Cisco ignores this. In North America they’re forecasting that the number of mobile-only internet users will go from 2.6 million to 55.6 million (!). It’s reasonable to assume that these most of these new users are in places that are already consuming a lot of capacity, and that one will need more radio bandwidth to deliver more data throughput.
Cisco is forecasting that throughput will go from 0.05 ExaB/mo to 1.0 ExaB/mo for North American users. That’s a factor of 20. It’s hard to see how you get there from here without massive reengineering of the infrastructure.
So by using heroically optimistic assumptions one can get an 8x increase in capacity – nowhere near that 20x Cisco is forecasting.
And last but not least, the forecast method ignores Econ 101: if demand increases with limited supply, prices will go up, and this will suppress demand. Not only does the study ignores supply, it also ignores supply/demand interactions.
Still, let’s stipulate that the demand forecast is accurate, and that grant me that supply is going to be constrained. The consequence is that there will be millions of screaming customers over the next few years when they discover that the promise of unlimited mobile connectivity cannot be delivered. The pressure on government will be huge, and the opportunities for innovations that improve effective throughput and the user experience in a world of scarcity (relative to expectations) will be immense. A crisis is coming; and with it the opportunity to make fundamental fixes to how wireless licenses are managed, and how applications are delivered.
The numbers are staggering: global mobile data traffic grew 2.6-fold in 2010, nearly tripling for the third year in a row; mobile video traffic will exceed 50% for the first time in 2011; and Cisco predicts that global mobile data traffic will increase 26-fold between 2010 and 2015. Big numbers forecast by someone who’ll make money if they come true are always suspect, though. While the historical data are largely indisputable – and amazing – I think the forecasts are bogus, though in interesting ways.
Flags went up at the projection of 92% CAGR in mobile traffic growth over the next five years. From the scant details on assumptions provided in the report, I suspect the overall growth is driven (more than driven, in fact) by the growth in the number of users, not by increases in per-user usage. For example, Cisco predicts that the number of mobile-only Internet users will grow 25-fold between 2010 and 2015 to reach 788 million, over half of them in “Asia Pacific” (defined to exclude Japan).
Working back from their forecast data volumes and assumptions on user growth, however, suggests that usage per user (I prefer to think in terms of Megabits/second rather than ExaBytes/month) doesn’t increase over the study period, an in fact declines.
The growth in traffic thus hinges on the global user base growing to almost 800 million mobile-only users in five years, from 14 million today. That’s staggering, and to me implausible.
If nothing else, though, this demonstrates that using Cisco’s meganumbers don’t necessarily imply an impending bandwidth crunch doesn’t hold water. It doesn’t mean there isn’t going to be one, just that growth numbers don’t imply/require it, because they’re in large part driven by hundreds of millions of new users in China.
A more fundamental flaw is that the analysis is entirely demand driven. This was probably fine when Cisco was predicting wireline use, since there is so much dark fiber that supply is essentially unlimited. However, one cannot ignore the scarcity of radio licenses. We’re near the Shannon limit of the number of bits/second that can be extracted from a Hertz of bandwidth, and massive new frequency allocations will not show up overnight. An alternative is to reduce cell size and serve more users per cell by using smart antennas; however, such a build-out will take time. I don’t know how much extra traffic one can fit into the existing infrastructure and frequencies, but Cisco should at least have made an argument that this doesn’t matter, or that it can ramp up as fast as the demand.
While there may be spare capacity in China, there’s clearly a supply question in markets that are already halfway up the growth curve, though, like the US. Cisco ignores this. In North America they’re forecasting that the number of mobile-only internet users will go from 2.6 million to 55.6 million (!). It’s reasonable to assume that these most of these new users are in places that are already consuming a lot of capacity, and that one will need more radio bandwidth to deliver more data throughput.
Cisco is forecasting that throughput will go from 0.05 ExaB/mo to 1.0 ExaB/mo for North American users. That’s a factor of 20. It’s hard to see how you get there from here without massive reengineering of the infrastructure.
- One could get 2x by doubling available licenses from 400 MHz to 800 MHz; the FCC is talking about finding 500 MHz of new licenses for mobile data, but this is a pipe dream; if not in principle, then in the next five years given how slowly the gears grind in DC.
- The extra throughput isn’t coming from offloading traffic from the wireless onto the wired network; Cisco considered this, and is forecasting 39% for offload that by 2015. Let’s say they’re conservative, and it’s 50%: that’s just another 2x.
- Spectral efficiency, the bits/second that can be extracted from a Hertz of bandwidth, isn’t going to increase much. Engineers have made great strides in the last decade, we’re approaching the theoretical limits. Maybe another 50%, from 4 bps/Hz to 6 bps/Hz? Even an implausible doubling to 8 bps/Hz is just another 2x.
So by using heroically optimistic assumptions one can get an 8x increase in capacity – nowhere near that 20x Cisco is forecasting.
And last but not least, the forecast method ignores Econ 101: if demand increases with limited supply, prices will go up, and this will suppress demand. Not only does the study ignores supply, it also ignores supply/demand interactions.
Still, let’s stipulate that the demand forecast is accurate, and that grant me that supply is going to be constrained. The consequence is that there will be millions of screaming customers over the next few years when they discover that the promise of unlimited mobile connectivity cannot be delivered. The pressure on government will be huge, and the opportunities for innovations that improve effective throughput and the user experience in a world of scarcity (relative to expectations) will be immense. A crisis is coming; and with it the opportunity to make fundamental fixes to how wireless licenses are managed, and how applications are delivered.
Saturday, October 16, 2010
Who gets the apple? Part II: A salty problem
Here's another analogy; one that includes a nod to dispute resolution. For those who know and/or love Coasian economics, it's our old friend the pollution example, though tweaked to be radio interference in light disguise. It's also, incidentally, based on a true story I heard from someone who works for a large county's water district.
Imagine a city along a river, and a downstream farming community. Urban development results in more salt being added to the river; increased salinity can reduce crop yield. Salty water is therefore analogous to radio interference between transmitters (cities) and receivers (farms).
The harm to crops is a shared responsibility, though. For example, the city can reduce the amount of downstream salt by building a water treatment plant, and the farmers can accomodate more salty water by changing crops - spinach will be fine on water that's too salty for celery.
Let's imagine that a Federal Crops Commission (call it the FCC2) is responsible for managing this problem. It might instruct the city and farms to "coordinate" to find a solution to the problem, with a guideline that water may not be "too salty". As in the apple example, this is difficult to do without defining what counts as too salty, and who bears the responsibility for salinity.
If the FCC2 limits the salt the city can dump in the river like the FCC controls radio emissions, it would specify a ceiling of, say, 5 tons of salt per day - with a rider that the resulting water can't be "too salty". This is not very helpful to the farmers, however, since they care about the resulting salinity; seasonal variations in water volume or the salinity entering the city limits from upstream affect the resulting salinty. It doesn't help the city either, since it can't be sure how much water treatment capacity to build; 4 tons/day of salt might still turn out to be too much if the farmers downstream choose salt-intolerant crops and/or the river level is too low.
Matters are compounded when the city and the farming community fail to reach agreement, and go to the FCC2 to resolve a conflict. (They have nowhere else to go, since the courts defer to the FCC2 as an expert agency to decide what "too salty" means in a particular case.)
Neither side can predict what the outcome of the FCC2's deliberations will be, since it doesn't always decide the merits of individual cases in isolation. It has many proceedings before it at any given time; for example, the FCC2 might be pushing the farmers to get organic certification, and negotiating with the city about the rezoning of agricultural land for urban development. The solution the FCC2 negotiates between the city and the farmers might encompass all these other matters, not only making the result of the salinity dispute unpredictable, but failing to establish a precedent that others might use later.
A better approach would be for the FCC2 to regulate the resulting salinity in water leaving the city (to, say, 5 ppm), remove any mention of "too salty" from its regulations, and provide a way for contending parties to get a specific case resolved efficiently. It might give the farmers the right to stop the city water plant releasing water into the river if the salinity exceeds 5 ppm (leading to a negotiated solution, where the city might pay the farmers' coop $300,000 to raise the limit up to 10 ppm in dry months), or if there are too farmers to negotiate with individually it might choose a liability regime (leading to a court-imposed payment of say $30/acre if salinity exceeds 5 ppm and some farmers sue the city).
Imagine a city along a river, and a downstream farming community. Urban development results in more salt being added to the river; increased salinity can reduce crop yield. Salty water is therefore analogous to radio interference between transmitters (cities) and receivers (farms).
The harm to crops is a shared responsibility, though. For example, the city can reduce the amount of downstream salt by building a water treatment plant, and the farmers can accomodate more salty water by changing crops - spinach will be fine on water that's too salty for celery.
Let's imagine that a Federal Crops Commission (call it the FCC2) is responsible for managing this problem. It might instruct the city and farms to "coordinate" to find a solution to the problem, with a guideline that water may not be "too salty". As in the apple example, this is difficult to do without defining what counts as too salty, and who bears the responsibility for salinity.
If the FCC2 limits the salt the city can dump in the river like the FCC controls radio emissions, it would specify a ceiling of, say, 5 tons of salt per day - with a rider that the resulting water can't be "too salty". This is not very helpful to the farmers, however, since they care about the resulting salinity; seasonal variations in water volume or the salinity entering the city limits from upstream affect the resulting salinty. It doesn't help the city either, since it can't be sure how much water treatment capacity to build; 4 tons/day of salt might still turn out to be too much if the farmers downstream choose salt-intolerant crops and/or the river level is too low.
Matters are compounded when the city and the farming community fail to reach agreement, and go to the FCC2 to resolve a conflict. (They have nowhere else to go, since the courts defer to the FCC2 as an expert agency to decide what "too salty" means in a particular case.)
Neither side can predict what the outcome of the FCC2's deliberations will be, since it doesn't always decide the merits of individual cases in isolation. It has many proceedings before it at any given time; for example, the FCC2 might be pushing the farmers to get organic certification, and negotiating with the city about the rezoning of agricultural land for urban development. The solution the FCC2 negotiates between the city and the farmers might encompass all these other matters, not only making the result of the salinity dispute unpredictable, but failing to establish a precedent that others might use later.
A better approach would be for the FCC2 to regulate the resulting salinity in water leaving the city (to, say, 5 ppm), remove any mention of "too salty" from its regulations, and provide a way for contending parties to get a specific case resolved efficiently. It might give the farmers the right to stop the city water plant releasing water into the river if the salinity exceeds 5 ppm (leading to a negotiated solution, where the city might pay the farmers' coop $300,000 to raise the limit up to 10 ppm in dry months), or if there are too farmers to negotiate with individually it might choose a liability regime (leading to a court-imposed payment of say $30/acre if salinity exceeds 5 ppm and some farmers sue the city).
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