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.