Interference control in cognitive wireless networks by tuning the carrier sensing threshold

The requirement for secondary spectrum usage is the control of secondary generated interference to the primary system. The generated interference from different types of secondary networks can be controlled by adjusting different parameters. The carrier sensing threshold can be used as a common parameter to control the density of active secondary users in wireless networks with contention control thereby enabling primary system protection. In this paper, we propose a method to set the carrier sensing threshold in secondary wireless networks with finite user density and finite deployment area. Based on the secondary user density, we first find the required distance separation among secondary transmitters so that the primary system service is protected. Given the distance separation, we set the carrier sensing threshold by computing the self-interference at a secondary user. Our method is illustrated for Matern type II and Matern type III point processes for modelling the locations of active secondary users due to the resemblance of these processes to CSMA/CA type of contention control.