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Apr 13, 2010

Patent: Signal Detection in Cognitive Radio Systems

After writing the post about the companies with most patents on cognitive radio I wondered how innovative these patents could be. To check it I present here one of the lastest patents filed by Motorola related to spectral sensing: US20100081387: Signal detection in cognitive radio systems.


The first claim, the soul of the patent, reads like that:
A method, with a cognitive radio wireless device, for dynamically managing signal detection in a cognitive radio system, the method comprising:
  • performing spectrum sensing for a first sensing frame on at least one communication channel;
  • receiving, in response to performing spectrum sensing, at least one observed signal on the at least one communication channel;
  • and performing a detection decision to determine if the observed signal is one of noise and an active signal associated with an active user, wherein performing the detection decision comprises:
    1. determining an energy estimation .epsilon. associated with the at least one observed signal;
    2. comparing the energy estimation .epsilon. with a current detection threshold, wherein the current detection threshold is one of an arbitrarily defined threshold and a detection threshold based on a previous detection decision for a sensing frame immediately prior to the first sensing frame;
    3. setting, in response to the energy estimation being above the current detection threshold, a first new detection threshold equal to the current detection threshold;
    4. and setting, in response to the energy estimation .epsilon. being below the current detection threshold, a second new detection threshold as a function of the current detection threshold and the energy estimation .epsilon.;
    wherein one of the first and second new detection threshold is used for at least one subsequent detection decision for at least a second sensing frame."

That is, they use energy detection in a given channel by comparing the meassured energy with a threshold that is updated in the case that the channel is decided as vacant.

A patent by definition
must be innovative to the point that it wouldn't be obvious to others."
Then my question is if updating the threshold after non-detection of a primary user is innovative enough in order to justify a patent, or most of these patents are just for the future work of their lawyer's offices.

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Blogger RandomGuy said...

I totally agree with you on this.

I do not think this needs to be patented. There are so many algorithms one can think of to set the threshold. Patenting each of them would keep the office busy. I think they should have published an academic paper rather than getting it patented.

May 13, 2010 at 7:31 PM  

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