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RHJPPLe 17/08/2011 à 23:29
Voici un extrait de l'article qui explique comment ça fonctionne* et qui correspond tout à fait à la définition de la formation de faisceaux :
Normally, when you have two very different radio signals colliding with each other, the result is one stronger signal overpowering the other (as in the radio station example given in the Background section), or just indecipherable noise from the two signals interfering with each other.

But, not with DIDO. Instead something rather remarkable happens: the sum of the radio signals at each computer’s location results in a clean modulated waveform carrying the data intended for that particular computer. So, the waveform received at User 1’s computer contains the video data sent by website 1, and the waveform received at User 2’s computer contains the video data sent by website 2. Each computer simply demodulates the waveform and plays the video for its user.
And, here’s the really amazing part: what each user receives is what they would have received if they had the channel to themselves, without another user sharing the same spectrum. There is no interference from the other user. Each user is able to utilize the full Shannon Limit of the channel.


* En fait, il ne l'explique pas, il dit que c'est mathématique et trop compliqué pour l'expliquer dans son papier... Et pourtant c'est bien là qu'il aurait pu apporter quelque chose de neuf pour accélérer les calculs. Aussi son système a besoin d'autant d'antennes que d'utilisateurs (comme en formation de faisceaux optimale), ce qui rend la chose bien moins attractive.