

How Will DIDO Wireless Networking Change Everything? - riledhel
http://highscalability.com/blog/2011/8/2/how-will-dido-wireless-networking-change-everything.html

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hadronzoo
> Using this new technology shared spectrum is not limited by Shannon's law at
> all. They can get 10x what Shannon's law is possible. They have 10 radios
> working, all at the Shannon limit on the same frequency and they do not
> interfere with each other at all. They think they can get to 100x, 1000x,
> they don't know what the limit is. They can do 100x what cellular does now
> with the same spectrum. This means no more dead zones. No more drops.

The wireless industry is notorious for snake-oil salesmen. When you actually
claim that your technology violates Shannon channel capacity, it doesn't
inspire much confidence that you understand information theory.

From the description (this is just a guess), it appears that DIDO offloads
channel characterization to a centralized server to reduce the computational
requirements of the clients (similar to AGPS). MIMO techniques (like DIDO) do
not violate Shannon capacity. They improve Eb/N0 by increasing gain through
beam-forming and physical antenna diversity. In addition, DIDO appears to be
using some form of asynchronous spread spectrum (even though they deny using
CDMA, there are many other flavors), which allows all clients to transmit
simultaneously by using orthogonal codes. Spread spectrum techniques also
improve gain at the expense of bandwidth.

While they may have a good implementation, I don't see anything earth
shattering here.

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VladRussian
>So, if there are 10 APs and 10 users all within range of each other, then 10
radio signals will sum together at each antenna of each user’s device to
produce an independent waveform for each device with only that device’s data.

we all know that using 10 AP devices you can generate desired independent
waveforms at 10 or less target positions in space. The question is whether it
is possible for 11, 12, etc... Interference result is a linear combination of
source waverforms. I.e a task sounds like "find M (with M less than N) vectors
satisfying these N linear independent conditions"

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olliej
Can anyone explain how this differs from the MIMO radios what have been around
for years?

