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Stanford Wireless Breakthrough

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Re: Stanford Wireless Breakthrough

#11

Post by JoeAltmaier »

regularfry wrote: post #10
JoeAltmaier wrote: post #4

The claim that this doubles the amount of information you can send is nonsense. It simply allows you to send and receive simultaneously.

...which, assuming you're sending and receiving equal amounts, doubles the amount you can send in a given time period. http://en.wikipedia.org/wiki/Duplex_(telecommunications)

Don't be trite. Receiving is completely different from sending. "You" doesn't include the other guy, in my dictionary.

It may raise the amount that can be sent over the network in toto, assuming that data demand is the same in all directions. Which it almost never is.

So what they've done is, they allow the data uplink to occur simultaneously with the downlink.

A valid claim is, the latency of data is improved - you don't have to wait/schedule your sends around the receive traffic. Which can matter quite a bit in the bulk of cases e.g. downloading http while jabbing buttons/sending commands up to the server.

Re: Stanford Wireless Breakthrough

#12

Post by troymc »

JoeAltmaier wrote: post #11
regularfry wrote: post #10

Earlier quoted context omitted.

...which, assuming you're sending and receiving equal amounts, doubles the amount you can send in a given time period. http://en.wikipedia.org/wiki/Duplex_(telecommunications)

Don't be trite. Receiving is completely different from sending. "You" doesn't include the other guy, in my dictionary. It may raise the amount that can be sent over the network in toto, assuming that data demand is the same in all directions. Which it almost never is. So what they've done is, they allow the data uplink to occur simultaneously with the downlink. A valid claim is, the latency of data is improved - you…

Some people don't know what they're going to say until they say it. If such people could send and receive at the same time, they would be getting more information per unit time.

Re: Stanford Wireless Breakthrough

#16

Post by lutorm »

zwieback wrote: post #9

Sounds very interesting but I wonder if the null of the transmitting antennas is stable in the presence of multipath reflections. This scheme also works only if all nodes have full-duplex setups, which is impractical for small devices.

No, reflections can have any phase, so you can't possibly cancel them out with a fixed geometry. But given the 1/r^2 falloff, unless the reflections are from very nearby, they will be a lot weaker than the direct path.

Re: Stanford Wireless Breakthrough

#17

Post by rmrm »

JoeAltmaier wrote: post #11
regularfry wrote: post #10

Earlier quoted context omitted.

...which, assuming you're sending and receiving equal amounts, doubles the amount you can send in a given time period. http://en.wikipedia.org/wiki/Duplex_(telecommunications)

Don't be trite. Receiving is completely different from sending. "You" doesn't include the other guy, in my dictionary. It may raise the amount that can be sent over the network in toto, assuming that data demand is the same in all directions. Which it almost never is. So what they've done is, they allow the data uplink to occur simultaneously with the downlink. A valid claim is, the latency of data is improved - you…

it's fairly standard terminology...you've doubled the amount of data that can be sent over a given chunk of spectrum per unit time, without changing the modulation/encoding scheme (bits/hz). A normal full duplex FDD system takes twice the bandwidth to pass the same amount of information as this theoretically can.

Rather than think about bursty, asymmetric Ethernet bits, consider passing something like a fully allocated T1 over it. Symmetric TDM links aren't totally dead, there are a lot of T1 radios out there. What used to take X Hz of bandwidth, theoretically can be done in X/2...without changing the modulation.

I don't think it will actually be used that way, but it is a breakthrough of sorts to be able to do so.

Re: Stanford Wireless Breakthrough

#18

Post by johngunderman »

lutorm wrote: post #14

I almost stopped reading after the first sentence: Radio traffic can flow in only one direction at a time on a specific frequency. Right... To be fair, the article improved after that.

It was just poorly phrased. by "direction" they meant "from receiver to transmitter" or "from transmitter to receiver".

Re: Stanford Wireless Breakthrough

#19

Post by hristov »

regularfry wrote: post #10
JoeAltmaier wrote: post #4

The claim that this doubles the amount of information you can send is nonsense. It simply allows you to send and receive simultaneously.

...which, assuming you're sending and receiving equal amounts, doubles the amount you can send in a given time period. http://en.wikipedia.org/wiki/Duplex_(telecommunications)

I don't think that is the case. Suppose a given channel (e.g. a frequency) has a maximum information per second it can carry X, this system will not allow 2X information to be carried. It will allow the information carrying capacity of the channel to be split, such that each side can carry a maximum amount of information A and B respectively such that A+B<=X.

Re: Stanford Wireless Breakthrough

#20

Post by powertower »

Can't each transmitter/radio add some type of a 2-nd order frequency onto the transmitting signal (imagine a sin-wave, except it's line is not smooth, the line has its own "frequency") and detect that to filter the incoming signal?
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