Anybody familiar with wireless comms know what this actually does and what the innovation is?
Is this distributed beamforming?
Is this distributed beamforming?
This is not a new idea -- phased array radars do essentially the same thing -- but it's a new application of the mathematical methods, and the complexity is much higher than for a modern radar because the system has to deal with many different devices, freely moving around, and calculate the optimal combination of radio signals to produce a high signal level at that devices's current location.
It is the high computation workload that makes Perlman emphasize the role of a data center, which would need to be added to an existing cell network, to make this method possible.
Cell systems already know how to determine the location of a given device using signal arrival times at multiple antennas. This method builds on that knowledge base to improve the outgoing signals, and possibly also to phase-adjust the reception antennas, to maximize signal quality in both directions.
In essence, the system computes a protocol for each outgoing packet, beyond the packet's data content. Each packet contains additional information for each antenna that will be used to transmit it, information about phase delay. Before the packet is transmitted, the required phase delay for each of the transmitting antennas is adjusted to correspond to the calculated best solution for that device at its present location. This process is performed for each packet, for each device, which explains the high computation workload.
If physically separate antennas are used for transmitting and receiving (usually true in cell service), a separate computation would be required to most efficiently receive packets from each device. I don't know if the system has this added level of complexity, but it's possible in principle.
Could this not be sped up in ASIC hardware? I'm not a hardware guy, but I would think a GPU could fit the bill for these sorts of geospatial on-the-fly calculations.
EDIT:
"Accelerating geospatial analysis on GPUs using CUDA"
http://www.zju.edu.cn/jzus/opentxt.php?doi=10.1631/jzus.C110...
Yes, it's called pre-coding, every modern wireless system does it. Doing it across wireless stations is distributed beamforming which Perleman did not invent.
Present cell systems don't adjust phase to maximize reception quality in a coordinated way for each of several transmitting antennas, for each packet, for each participating device. That's new.
> Doing it across wireless stations is distributed beamforming which Perleman did not invent.
That's certainly true -- phased array radars have been doing this for decades. But Perlman should be able to get a patent anyway, based on the combination of ideas this scheme represents. Multiple, physically separate antennas, the use of a data center to compute solutions on the fly to accommodate multiple antennas and different devices with different locations, that's new.
You are just describing MIMO pre-coding which has existed for more than 20 years.
I don't see what is patentable: Distributed beamforming necessarily requires physically dispersed antennas. Adding a data center doesn't seem patentable. But I don't know anything about patents nor do I care that much.
Being a critic of software patents myself, and given how much this idea relies on software and mathematics (mathematics is definitely unpatentable), I agree that it's an issue.
I suspect that the entire method is patentable even though each element taken separately isn't.
Link: http://en.wikipedia.org/wiki/Mobile_phone_tracking
Quote: "Mobile phone tracking refers to the attaining of the current position of a mobile phone, stationary or moving. Localization may occur either via multilateration of radio signals between (several) radio towers of the network and the phone, or simply via GPS."
That said, I continue to remain dubious because his claims are fairly out there in terms of bandwidth. I don't know if Claude Shannon were alive today if he could figure out if there was an upper limit of directed traffic in a channel but that is the principle that feels like its being violated here. All of my training has taught me to think of a bit of spectrum like a single wire, and sure you can attach a bunch of things to that wire, but there isn't a lot of theory around how that becomes a bunch of separate but equivalent channels.
No additional bandwidth is required beyond what cell systems already provide. The idea behind this method is that each outgoing packet has some extra information about phase for each antenna that will be used to transmit it.
The extra information is calculated using Perlman's data center and added to the data structure of a specific packet meant for a specific device. The extra information tells the transmitting antennas which phase delay to apply to maximize the signal at the device's current location.
My point is that this method doesn't change the bandwidth required for the cell system -- in many ways everything is as it was before, except that each participating device experiences better reception.
This system relies on a relatively simple phase adjustment at each transmitting antenna, but because of the number of devices, the number of antennas and the math involved, a dedicated data center would have to be added to an existing cell system.
But there's no change in terms of bandwidth -- that remains the same.
"In demonstrations at his laboratory, Perlman showed off iPhones, Surface tablets, and TVs streaming massive files—the 4K UltraHD version of House of Cards from Netflix, for example—via his own wireless networking equipment"
These are both bandwidth narratives, not signal quality narratives. (granted they are the naive reporter's narratives but still). His breakthrough is that "all these devices can stream 4K ultra HD" that says that somehow he getting more bits to more machines, and that is a function of bandwidth not signal strength.
Lets assume for the moment that the basestation is connected to some multi-lambda super fiber with a 40G connection back to the Internet. He's going to give every LTE phone a 100Mbps to 1Gbps connection to that? That works for the first 400 or 40 people but then what? 5 bars and stuttering video?
This story, and others like it, have made the argument that the problem is congestion not signal clarity. Congestion is a function of channel bandwidth and operation rate. That is what leaves me dubious, I haven't seen how he can increase the bandwidth of the channel with his gizmo.
To me, the first sentence in your quote from the article is simply hyperbolic but has no connection with reality. The method doesn't do away with network congestion, it simply improves the signal at each participating device.
> Congestion is a function of channel bandwidth and operation rate.
I think the congestion this method addresses is that caused by unsophisticated signal treatment methods and an overall decline in performance. Obviously if the system can optimize the phase at each transmitting antenna and improve the received signal for each device, then more devices can use the system simultaneously. That's not how I would define "do away with network congestion", but again, I think the journalist just had no idea what he was describing.
I think the reason for all the attention given to this method is because it greatly improves the performance of a cell system without requiring any bandwidth increase. Remember that dropped packets are at times a big limitation on cell system performance, and much existing bandwidth is often wasted on packets that don't get decoded properly because of weak signals.
> It's as if only a single cell phone was in a given tower cell, and the tower was dedicating all its bandwidth to that single phone.
If the system can adjust the phases of the transmitting antennas to maximize the signal strength to a particular device, for each transmitted packet, then for all practical purposes that's true -- the entire bandwidth of the system really does become available to that particular device, for the duration of each packet meant for it.
I don't know the statistics on dropped packets, but I think it's substantial in modern times for high-speed networks. The ratio of dropped packets essentially represents a bandwidth decrease. If that could be eliminated, it would improve throughput, and someone will be tempted to claim that bandwidth has increased. Only sort of.
That could certainly accommodate a situation of everybody in a room streaming the same 4k content.
I'm predicting that the breathless claims of "no limit" are based on being the only show in town. As long as the system is controlling every transmission in a volume of space it will do well, and you will be able to add users until you reach the same limits that a MIMO system would hit if it was the only transmitter. Start adding uncontrolled interference, and things will start to degrade.
Maybe the next step, would be for the distributed base stations to use receivers to sample the spectrum. This data could be fed back into the cloud and an attempt be made to predict and cancel the uncontrolled interferers. The FCC (or local equivalent) might take a dim view of this though, if it turned out that the cancellation was effectively jamming other users.
--- Edit.
Just adding, in my experience, if you want to understand the latest radio communications technology, speak to a radio astronomer. When MIMO first came out and people were trying to figure out its limits, it turned out that the radio astronomers already knew the limits, based on their knowledge of large antenna arrays. I'd guess the astronomers would look at this current technology and think "very long baseline interferometry".
I imagine two phones X and Y and one antenna sends X XOR Y while the other sends X XOR Y XOR Y. A phone getting both signals could determine X and Y, but it would take twice as much bandwidth. If you can XOR the signals in the air through superposition somehow, X might be received in one location, and Y in another.
So 2 antennas cant service more than 2 phones at full speed, but they can service those two phones at full bandwidth. This might not seem like an advantage over directional antennas, but it relaxes the physical constraint of making sure the phones are in two separate enough places to be serviceable by the two antennas. Like maybe your phone would have two antennas and get twice the data--not very feasible if your phone were somehow serviced by two directional antennas.
I haven't worked out how superposition could do something exactly like XOR, or if it maybe has a minimum of 3 antennas to start being possible, etc., but it seems plausible.
Anyway, the idea would be sending signal X and Y. You want X interfering with Y at some time offset to yield desired phone signal A, and X interfering with Y at some other time offset to yield phone signal B. The phones never receive X or Y, but some superposition of the two, The phones couldn't cheat and just record the two waves and timeshift internally to yield twice the bandwidth, because they don't receive the two waves separately, they only get the superposition of the two.
XOR is just a primitive way of making an orthogonal code.
I would expect he would be more successful patenting the hell out of it and licensing it to Ericsson, NSN, Qualcomm, Cisco, etc than trying to sell it to individual venues and customers.
Basically the base arial seems to focus a 1cm wide beam at each device. Works nicely in his lab but dunno how well that'll work using your phone in the car.
> The more antennas you have, the cleaner you can keep the beam and minimize constructive interference happening in the wrong places.
Beyond three antennas surrounding a given device, this just isn't true -- more antennas don't produce a proportional increase in performance to compensate for the increased computation workload.
Yes, true, but the entire system becomes more complex for a small improvement in performance. Also, most of the theoretical work in a scheme like this would focus on the least common denominator, which is three antennas.
Interestingly, for a roughly circular array of antennas, you end up with concentric rings of high signal strength as you approach the midpoint of the array. So even the thesis that you've eliminated unused hot spots breaks down in some cases.
Here's my diagram for three phase-controlled antennas (the blue dots):
http://i.imgur.com/tyyVh0j.png
The wavelengths in this diagram are longer than for a cell system, it's just to show how this idea works. Buy adjusting the phase at each antenna, you can move the high-strength lobes around to match up with the location of a given device.
Typical beamforming just boosts the signal quality, on a slice of the available spectrum. But it would be faster if you used the whole bandwidth. But then no one else would be able to use that bandwidth. But if you used a parabolic antenna pointed at each receiver, then each phone would get the full bandwidth. But if the phone is moving, you can use (tracking antennas or...) deliberate interference within a "mesh" of antennas.
See: http://blog.airtightnetworks.com/bang-for-the-buck-with-expl...