6 ms·

Anybody familiar with wireless comms know what this actually does and what the innovation is? Is this distributed beamforming?

cantfindmypass 13y ago
No. The transmitters calculate signals such that constructive/destructive interference will combine to form a strong, clean signal in the precise location where the device is.
- bdcs 13y ago
  Correct me if I'm wrong, but is this not beamforming?
  - gallamine 13y ago
    Perhaps the "trick" is a large number of antennas to produce an ultafine beam pattern?
    - lutusp 13y ago
      No, it's not the number of antennas (although there is always more than one), the method relies on the phase (or "time delay") of the signal at each antenna.
      - Dylan16807 13y ago
        Why do you say no? The more antennas you have, the cleaner you can keep the beam and minimize constructive interference happening in the wrong places.
        lutusp 13y ago
        I say no because the system relies on multiple antennas, but beyond a few, the advantage evaporates while the workload increases. I wouldn't be surprised if the system limits itself to three well-placed antennas surrounding the target device, just to simplify the calculations. > 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.
        foobarian 13y ago
        Not for one client device, but it definitely helps when handling lots of clients. The more antennas the fewer spots with unwanted constructive interference.
        lutusp 13y ago
        > The more antennas the fewer spots with unwanted constructive interference. 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 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.
    - foobarian 13y ago
      The trick is getting that many antennas deployed in an urban area. They also have to be wired, and have reliable low latency connections to the datacenter.
  - lutusp 13y ago
    The problem is not the idea, but the word. Most people don't think of constructive phase adjustments as beamforming. It's not wrong, it's just an unfamiliar term.
  - deleted 13y ago
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tim333 13y ago
I don't know much about wireless coms but there's a nice video of him demoing it at http://news.cnet.com/8301-1035_3-57619072-94/is-pcell-the-holy-grail-of-wireless-networking/ http://news.cnet.com/8301-1035_3-57619072-94/is-pcell-the-ho... 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.
lutusp 13y ago
Without knowing the details (which are still secret for good reason), before transmitting a packet to a specific device, the system computes an ideal transmission wavefront from multiple antennas to maximize the signal quality at that specific device. 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.
- foobarqux 13y ago
  > This is not a new idea -- phased array radars do essentially the same thing -- but it's a new application of the mathematical methods[...] 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.
  - lutusp 13y ago
    > Yes, it's called pre-coding, every modern wireless system does it. 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.
ChuckMcM 13y ago
Reading Perlman's descriptions it does sound like distributed beamforming. Perlman is a smart guy, although I expect he would be more successful selling this technology initially to crowded venues (think large stadiums, or conference centers) which would allow those venues to both offer consistent high performance access to fans as well as high performance wireless channels for things like flying cameras (which is currently quite the mismash of technologies). 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.
- lutusp 13y ago
  > That said, I continue to remain dubious because his claims are fairly out there in terms of bandwidth. 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.
  - ChuckMcM 13y ago
    "The technology would do away with wireless network congestion by giving each smartphone and tablet its own super-fast connection instead of asking these devices to share bandwidth pumped out by a cell tower." "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.
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godojo 13y ago
Sounds exactly like 802.11ac. See: http://blog.airtightnetworks.com/bang-for-the-buck-with-explicit-beam-forming-in-802-11ac/ http://blog.airtightnetworks.com/bang-for-the-buck-with-expl...
oneiric 13y ago
Yes, plus more bandwidth. 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.

cantfindmypass 13y ago

No. The transmitters calculate signals such that constructive/destructive interference will combine to form a strong, clean signal in the precise location where the device is.

bdcs 13y ago
Correct me if I'm wrong, but is this not beamforming?
- gallamine 13y ago
  Perhaps the "trick" is a large number of antennas to produce an ultafine beam pattern?
  - lutusp 13y ago
    No, it's not the number of antennas (although there is always more than one), the method relies on the phase (or "time delay") of the signal at each antenna.
    - Dylan16807 13y ago
      Why do you say no? The more antennas you have, the cleaner you can keep the beam and minimize constructive interference happening in the wrong places.
      - lutusp 13y ago
        I say no because the system relies on multiple antennas, but beyond a few, the advantage evaporates while the workload increases. I wouldn't be surprised if the system limits itself to three well-placed antennas surrounding the target device, just to simplify the calculations. > 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.
        foobarian 13y ago
        Not for one client device, but it definitely helps when handling lots of clients. The more antennas the fewer spots with unwanted constructive interference.
        lutusp 13y ago
        > The more antennas the fewer spots with unwanted constructive interference. 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 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.
  - foobarian 13y ago
    The trick is getting that many antennas deployed in an urban area. They also have to be wired, and have reliable low latency connections to the datacenter.
- lutusp 13y ago
  The problem is not the idea, but the word. Most people don't think of constructive phase adjustments as beamforming. It's not wrong, it's just an unfamiliar term.
- deleted 13y ago
  [deleted]
deleted 13y ago
[deleted]

tim333 13y ago

I don't know much about wireless coms but there's a nice video of him demoing it at http://news.cnet.com/8301-1035_3-57619072-94/is-pcell-the-holy-grail-of-wireless-networking/ http://news.cnet.com/8301-1035_3-57619072-94/is-pcell-the-ho... 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.

lutusp 13y ago

Without knowing the details (which are still secret for good reason), before transmitting a packet to a specific device, the system computes an ideal transmission wavefront from multiple antennas to maximize the signal quality at that specific device. 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.

foobarqux 13y ago
> This is not a new idea -- phased array radars do essentially the same thing -- but it's a new application of the mathematical methods[...] 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.
- lutusp 13y ago
  > Yes, it's called pre-coding, every modern wireless system does it. 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.

ChuckMcM 13y ago

Reading Perlman's descriptions it does sound like distributed beamforming. Perlman is a smart guy, although I expect he would be more successful selling this technology initially to crowded venues (think large stadiums, or conference centers) which would allow those venues to both offer consistent high performance access to fans as well as high performance wireless channels for things like flying cameras (which is currently quite the mismash of technologies). 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.

lutusp 13y ago
> That said, I continue to remain dubious because his claims are fairly out there in terms of bandwidth. 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.
- ChuckMcM 13y ago
  "The technology would do away with wireless network congestion by giving each smartphone and tablet its own super-fast connection instead of asking these devices to share bandwidth pumped out by a cell tower." "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.

deleted 13y ago

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godojo 13y ago

Sounds exactly like 802.11ac. See: http://blog.airtightnetworks.com/bang-for-the-buck-with-explicit-beam-forming-in-802-11ac/ http://blog.airtightnetworks.com/bang-for-the-buck-with-expl...

oneiric 13y ago

Yes, plus more bandwidth. 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.