Method to improve diversity gain in a cooperative spectrum sensing network

A method of cooperative sensing in a cognitive radio (CR) network, comprising:

• selecting a group of subscribers;
• cooperatively sensing data in the form of hard decisions and soft information from the group;
• validating of the group of users by comparing the sensed data relative to a cooperative sensing index (CSI) metric to determine an achievable spatial diversity gain within the group, wherein the step of validating the group of subscribers comprises:
• choosing an initial number of subscribers;
• randomly selecting the chosen number of subscribers within the group;
• selecting sensing measurements from the randomly selected subscribers;
• estimating the CSI metric based on the randomly selected sensing measurements;
• comparing the estimated CSI metric to a CSI threshold;
• increasing the sample size of sensing measurements when the CSI metric exceeds the CSI threshold(s);
• and
• providing an achievable spatial diversity gain for the selected subscriber group when the CSI comparison indicates that there are no uncorrelated users are within selected the group,
• wherein the CSI metric is based on a statistical Entropy metric as a measure of the uncertainty or randomness;
• comparing the achievable spatial diversity gain of the group to a predetermined spatial diversity gain requirement;
• and
• communicating by the group of subscribers within the primary system's spectrum in response to the group of subscribers having an achievable spatial diversity gain that meets the primary systems predetermined spatial diversity gain requirement.