Collaborative wideband sensing based on subspace pursuit for cognitive radios

Spectrum sensing techniques are useful to increase spectrum utilization in a cognitive radio network by sensing spectrum holes without harmful interference. The collaboration of sensing information among cognitive radio nodes can significantly increase the reliability of spectrum sensing. Due to hardware limitation, each cognitive radio node has to sense one narrowband channel at a time. Consequently, the sensing procedure consumes a lot of time to get the sufficient information. A wideband sensing method is used to reduce the time overhead. Each node only senses a small amount of linear combinations of the information of all channels, and then transmit this low dimensional detection vector to the fusion center where the information is reconstructed. As a result, the time overhead and the communication overhead are significantly reduced. Four performance measures have been observed in the system which considers the call hold and residence of both licensed users and cognitive radio nodes.