4 ms·

How Will DIDO Wireless Networking Change Everything?

6 points by riledhel 15y ago

VladRussian 15y ago
>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"
olliej 15y ago
Can anyone explain how this differs from the MIMO radios what have been around for years?
hadronzoo 15y ago
> 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.

6 points by riledhel 15y ago

>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"

olliej 15y ago

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

hadronzoo 15y ago

> 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.