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New 'pCell' Technology Could Bring Next Generation Speeds To 4G Networks
An anonymous reader writes in about a possible game changer in wireless technology that embraces interference with great results: "It's one of those elegant inventions that only surface maybe once a decade. If it works at scale, according to IEEE Spectrum, it could 'radically change the way wireless networks operate, essentially replacing today's congested cellular systems with an entirely new architecture that combines signals from multiple distributed antennas to create a tiny pocket of reception around every wireless device.' This scheme could allow each device to use the full bandwidth of spectrum available to the network, which would 'eliminate network congestion and provide faster, more reliable data connections.' And the best part? It's compatible with 4G LTE phones, which means it could be deployed today."
The idea is that an array of dumb antennas are deployed and a very powerful cluster computes signals that are sent from all of them which then appear to be a single coherent signal to only a single device. There's a short paper on the Distributed In Distributed Out technique, but it is a bit light on the mathematical details.
So like Warp 9.5 then?
The big wireless operators haven't even finished rolling out (let alone paying for) their 4G rollout, and somebody thinks they're going to scrap it all and spend billions more rolling out new technology? O-K....
Being able to transmit more strongly is all well and good, but the phone can only send using so much juice. If you turn up the power of the phone too much it will just get in the way of other phones' transmission like they do now.
Still, half of a solution is better than nothing, I suppose.
It sounds like a logical extension of phased-array technology. Or, sort of how they do radiation cancer treatment with dozens of weak beams converging on one spot.
However, in order to get this to work well, you need the transmitted signal to be phased-aligned to within an appreciable fraction of a wavelength. Since we are around a gigahertz, that means that the phase of the carrier should be accurate to within a couple hundred picoseconds, max. How you maintain this accuracy over multiple cell sites confuses me. Of course, this is all a wild-ass guess on how the technology works.
"-1 Troll" is the apparently the same as "-1 I disagree with you."
Sounds like more of the same beamforming they've done for years, just more of it spread further apart.
So DIDO, distributed in distributed out... sounds like MIMO with more antennas, more distance between them (surrounding the targets, even)
I'm not sure why this isn't an obvious extension of MIMO. Harder to do, sure... and cool that it's coming... but obvious in concept.
That’s where things get interesting. Say, for example, you play a YouTube video. The pCell data center would request the video from Google’s servers, and then stream it to your phone through those 10 antennas. But here’s the key innovation: No one antenna would send the complete stream or even part of the stream. Instead, the data center would use the positions of the antennas and the channel characteristics of the system, such as multipath and fading, to calculate 10 unique waveforms, each transmitted by a different antenna. Although illegible when they leave the antennas, these waveforms would add up to the desired signal at your phone, exploiting interference rather than trying to avoid it.
If we colonize Mars, it won't be the World Wide Web anymore. UWW?
For when the GPS is turned off. Or maybe pCELL combined with GPS means that google maps won't send me the wrong direction down a deadend road again.
Well, I can't comment on the prices, but several things go into the voice quality...
1) Voice quality is actually pretty good if you stick to a POTS land-line. Back in the 60's, everything was analog, so the noise added up.
2) Cell phone reception certainly can be bad, but back in the 80's when cell phones were invented, you had giant phones that could pump out a couple of watts because you had a large antenna and large batteries. Modern phones have tiny batteries and tinier antennas. This is partially compensated by a better noise floor on the cell-site receivers, but there ain't no such thing as magic.
3) Old analog cell phones transmitted actual analog voice at full bandwidth. While a waste of bandwidth, it sounded pretty good. Modern phones compress the heck out of your voice before sending it. The last time I checked, it was using some variant of CELP, which sounds fairly good, but far from perfect.
4) Data is now packetized (part of the compression). If you loose any part of the packet, you loose about 1/4 second of voice or so. In analog phones, you would hear a pop. or 1/10 second of silence.
"-1 Troll" is the apparently the same as "-1 I disagree with you."
All that's left is figuring out *who* will be suing him first. CISRO? Intellectual Vultures?
I think you meant "lose" rather than "loose" you can blame it on autocorrect if you want ....
I know the NSA is behind this ... I mean, tracking phones down to centimeter precision.
we need to focus our technology on designing base stations and cellphones that utilize directed-energy, focusing their signals at each other, versus using omnidirectional energy (this creates a lot of waste, and the energy penetrates and bombards people/things it doesn't necessarily have to,..).
with an imaging system like this, the base station can see each device independently, like a satellite does from over head, and an array of light-guns or phased array antennas can direct energy at each device for dedicated bandwidth and perfect signal reception over greater distances. an added benefit is lower output power works, and many devices can share the same spectrum..
the device itself would pick up the directed signal, and similarly lock on to the base station and beam a laser/directed energy right at it with dedicated bandwidth.
The military has technology like this already in deployment which they generally use to attack people.. http://www.oregonstatehospital...
In 1960, a phone call could be placed from any point in the United States that had a 10 lb telephone hard-wired to it to any other point in the United States that had a 10 lb telephone hard-wired to it and the sound quality would be consistently good.
FTFY.
This sounds very like the existing 3G soft handover feature.
I'm not involved in that area of telecoms these days, but I do recall that the network equipment manufacturers were finding it very difficult to get working, and requiring some serious compute power.
Yeah, that was my reaction too - I remember in the 60s and 70s "finding a phone" was a recurrent task, and the idea that one could call from "any" point was the thing of science fiction.
Wir sind geboren, um frei zu sein - Rio Reiser
Actually, you wouldn't have to deploy millions. You could deploy a couple doze in a ball park, for example, and get a good boost in capacity. And operators are already investing in infrastructure like this, such as small cells to try to cover places like ball parks. Infrastructure-wise, pCell wouldn't present any more challenges than small cells. In fact, they might even be a bit cheaper and simpler because they can be installed anywhere in a given area. You don't want one on your roof, but maybe your neighbor doesn't mind.
As cool as the technique sounds, for me it's a solution to the wrong problem. Maybe some of you have trouble getting your videos streamed in congested cities, but I don't use my phone for that. My complaints are all about poor coverage in rural and even some suburban areas. And I have Verizon, which because it unfortunately swallowed Alltel (I'm not aware of any Alltel customers that were happy about that), has much better coverage in my area than the rest. What they need is a few hundred thousand more nodes in rural and suburban areas on ordinary utility poles, inside of steeples, etc.
Unless you're trying to stream live video up from your phone [...] you don't really need it.
What do you think Skype and FaceTime are?
(I'm not used to the tuchpad on my new laptop and seem to have actidentally posted mid-edit. Reposting the full version.)
Even though it is technically compatible with 4G you still have to deploy millions of new antennas. He may have invented the greatest wireless technology ever, but it's dead on arrival due to cost.
Actually it may be cheaper than buying more spectrum and putting in more equipment at the cell sites, since it doen't involve buying more spectrum.
It DOES involve putting in more cells. But far fewer than you'd need to put in to subdivide the cells, in the normal cellular paradigm, to get the same amount of bandwidth reuse multiplication.
Also: You can bootstrap it by putting the new computation into just the existing cells, letting you handle more connections than with the old scheme. (After that it's add more cells in the customary maner, with more bang per buck.) Not only that, you only need to do it in areas where you're already running out of base station capacity and starting to suffer service level problems due to oversubscription/congetioin. If replacing/upgrading the equipment in existing cells gives you more additional connections per buck than the alternatives, there's no adoption cliff at all.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
Mobile phone reception is atrociously bad considering the prices mobile companies demand.
In 1960, a phone call could be placed from any point in the United States to any other point in the United States and the sound quality would be consistently good.
Now you can't make a call down the street without it sounding like the person at the other end is being beamed through an interdimensional time warp.
Your definition of "any point in the United States" leaves a lot to be desired, but yes cell phones do compromise sound quality for low power consumption and usable signal.
"It DOES involve putting in more cells. But far fewer than you'd need to put in to subdivide the cells, in the normal cellular paradigm, to get the same amount of bandwidth reuse multiplication."
From the descriptions, it sounds like it's basically phased-array technology, which has been in use in radar systems for decades. Of course this is a vastly different application and involves active feedback, so while the physics might be the same the rest isn't.
This was actually done for public wi-fi many years ago. It worked, but it turned out the cost was not much if at all lower than just coverage with simpler hotspots. But again: this is a different application and these are different circumstances. It might turn out better.
Ideally the phones would have a similar mechanism but current 4G LTE phones do not. they are omnidirectional and broadcast noise in all directions, even if the antenna system is at a specific location.
That doesn't matter. You just do the equivalent computation on the returned signal. You "listen" separately to the individual bubbles, just as you send separately to them.
So you only need to do it at one end - the one where coordinating and combining the signals is practical.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
In 1960, a phone call could be placed from any point in the United States that had a 10 lb telephone hard-wired to it to any other point in the United States that had a 10 lb telephone hard-wired to it and the sound quality would be consistently good.
FTFY.
... and the sound quality would be consistent. A lot depended on where the source and destination were, and the trunk quality between the various stations, but once you had a circuit, you had a circuit for the entire duration of the call, even if there was crosstalk, line noise, or what have you.
When our name is on the back of your car, we're behind you all the way!
It took me 3 reads to see that he wasn't talking about cell phone.
Then I was like WTF?
There are two types of people in the world: Those who crave closure
... and the sound quality would be consistent. A lot depended on where the source and destination were, and the trunk quality between the various stations, but once you had a circuit, you had a circuit
... until you were cut off unexpectedly and found yourself listening to either a dial tone or a busy signal depending on the era.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
The only similarity between DIDO and MIMO, as far as I understand it, is that they both use multiple antennas to send and receive separate data streams simultaneously. But their signal processing schemes are very different.
Not really. See below.
In broad strokes: DIDO does the signal processing (matrix math) on the transmitter side while MIMO does it on the receiver side.
Nope. MIMO does it at BOTH ends, to multiply the bandwidth between the two ends of the path by up to the number of antennas at the end with the smaller antenna count. The subchannels are, or can be, actually received by all the receive end antennas and sorted out in the receiver.
DIDO is MIMO with:
- The computation done so each remote-end antenna gets exactly one subchannel of the data (rather than a weighted and phase-shifted sum of all subchannels).
- The antennas at both ends very widely separated.
Sorting the signals this way allows the "remote end" to consit of many, independent, single-antenna devices, each with an independent data pipe as broad as the assigned spectrum. The wide separation of the antennas at both ends of the link makes a very large coverage area practical. Motion of the remote end devices just corresponds to a variation in the position and spacing of a remote-end MIMO device's antenna, requiring update of the parameters of the computation.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
As I read this, DIDO is exactly "steerable null" with the antennas spread out.
Of course the antennas are spread out VERY FAR APART, as in to multiple sites using a central computation of the I/Q signal and synchronizing separate local oscillators at the remote sites. This results in "bubbles around", rather than "beams at", those cellpphones that are in among the antennas.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
Micrel SY89295U
Programmable delay range: 3.2 ns to 14.8 ns in 10 ps increments in 2^10 discrete steps.
160 ps rise/fall, less than 2 ps RMS cycle-to-cycle jitter.
That gives you a spatial resolution of about 3 mm within a 3 m pixel on the fine delay; more if you also introduce a coarse delay line (in 10 ns increments). I think the Xilinx DCM gives a step delay on the order of 10 ps in 1024 discrete steps. You've now got 3 mm steps out to 3 km. Note that the linearity of these delay lines is not perfect, so there's some art to it (it's not a simple two-digit number in base 1000), but the worst case step remains small. You might use two DCMs in series plus the CML Micrel to ensure uniform coverage (one Spartan 3E has four DCMs IIRC). Actually, for a multi-channel base station, you'd need to fabricate an ASIC with a very large number of programmable delay lines, as I imagined it before RingTFA.
If the phone is 150 m away from a cell transmitter, you can set up a ping pong ping loop with a round-trip frequency of 1 MHz, where each end bats the pulse back as fast as possible.
Imagine the phone sends out a coloured packet and two or more base station pong it back. The phone can ping back on the first received response, or the last, or the n'th response in between. The fastest paths need to be artificially delayed until all paths are equal time. (With multi-pathing, the radio might be able to detect and measure more than one path length per base station.)
It would take long to achieve the coarse lock-on. Then it needs to maintained during motion of the mobile end, plus changes in atmospheric conditions, or sway in the buildings you're bouncing off of, if you've used the loudest path instead of the quickest path. The timing fabric is quite doable. The delay line can be anywhere in the ping pong circuit. The non-radio portions would ideally use fibre as copper has a temperature-variable c that adds up quick in the ps regime where lengths of 100 m are involved.
I can totally see this working, though radio systems at this level are astrobuck black magic.
The software-defined LTE phased array waveform simulation would be an interesting computational problem. They probably do the time extraction with DSP rather than actual delay lines. I'm wondering how much the upstream channel borks total throughput.
Maybe this is the Netflix special. Agility is always the last crow.
This reminded me of the claims Steve Perlman made in 2011. He said his technique would overcome Shannon’s Law. He was justifiably ridiculed. At least this mob isn't claiming they can break the laws of physics.
Oh wait, this is Perlman, peddling the same dog and pony show. Only this time he's got an article in IEEE Spectrum to print his claims. I hope that means he no longer says he can beat the laws of physics into submission.
The original claims of the impossible aside, the idea was to monitor the signal of each phone in real time from a central point, do some calculations to figure out the path distance from each antenna the phone, then do some more calculations to split up and phase change outgoing signal so the signals from those antennas so they constructively interfered to produce the wanted signal at the phone. The tracking has to be damned accurate - much better than GPS because a 1Ghz mobile phone signal has a wave length of about a meter, and you need better than 1/4 of the wavelength. And it has to be fast, because if the phone or objects around it move it all goes to put. So if you are walking at comfortable 1 metre per second, in 0.25 seconds it's all gone to pot. In a car that drops to 0.02 seconds. Oh, and since we as talking 1GHz, we have to measure it within a few 100 picoseconds. And since you don't use one antenna to service just one phone, he will have to be doing this for 100's of phone simultaneously. Oh, and that means when he is calculating the phase and amplitude of the signal his antenna is generating, he has to solve 100's linear equations with 100's of variables so he can ensure each signal he sends from each antenna adds up to what each phone needs. And since the collective antenna group is sending at oh, say 100Gb/s and he has to do this for every fucking bit, so he has 10 picoseconds per bit to do it in.
Yeah, right. It will be out by Xmas, I'm sure.
So they're bringing super fast speeds to a device 50x slower than my PC that's almost impossible to type on and has a processor that makes a playstation 2 look good. Great idea. And before you say it, you'd have to be an idiot to put your whole house on a 4G wifi hotspot. I'd use the cap in about 1 day under normal use. The cell network isn't built for that kind of traffic. They should be putting money into battery research and better encoding and bandwidth usage so towers are more effective and phones don't need a charge daily. That's the top improvements smartphones need, not speeds above 10 megabits.
(I'm not used to the tuchpad on my new laptop and seem to have actidentally posted mid-edit.)
The cure for this is to disable the trackpad (Alt+F7 on many laptops) and use the arrow keys or a mouse. WFM.
Thanks, but alt-f7 doen't do it on mine (which is running ubuntu 12.04 LTS>. Instead it emulates a left-click-and-hold to grab the object under the cursor.
I've got a little script that lets me toggle the enable/disable state but hadn't hooked up the mouse and activated it just then, so the touchpad was live.
I've tried to find an option for havig the the touchpad automagically go dead when the mouse is live (as windows has), but haven't found it in Ubuntu 12.04's unity. If anybody knows how to set that please let me know.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
Sure, but will they be able to construct these "bubbles of bars" for thousands of users around 2-5 antennae [ie, support the same number of users for the same antennae density]. And track each of antennae in those phones to the nearest cm [1/2 inch in American] as they move in realtime, and recalculate how to move the '5 bars bubble' to be where the cell phones antennae is, even as the phone moves in an unpredictable fashion.
And this doesn't improve the signal from the phone to the tower.
Theoretically, this system is possible, but it requires some crazy powerful computers to track thousands of phones and then figure out the wave patterns in real-time to make it work.
Sleep your way to a whiter smile...date a dentist!
The computation for DIDO (- steerable null) is a matrix multiply. Two additions + 2 adds times the product of the number of base station antennas and the number of active remotes.
Sorry, typo: Two multiplies and two adds. Ammortized per channel it's only an extra (multiply and add) * 2 * number of antennas for each I + Q sample of the generated waveform.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
But doesn't recreating a waveform by summing several other waveforms require that those components be of significantly higher frequency? Basic Taylor series stuff? E.g. recreating a 1 GHz carrier at the receiver from 10 random-distance sources would require each of those sources to be in the order of 10 - 100 GHz, especially if those transmitted waveforms are further constrained to be simultaneously delivering signals to other receivers.
No. Not at all. You are just summing 1 GHz. Simple (or not-so-simple) constructive and destructive interference...
"-1 Troll" is the apparently the same as "-1 I disagree with you."