Date Added: Jun 2011
In order to avoid interference to primary users within cognitive radio, a multi-frequency RTS/CTS scheme is studied in this paper. Assuming that channels suffer from Rayleigh fading and shadowing, the authors derive a closed-form of interference avoidance criterion based on multi-frequency RTS/CTS scheme. Simulations are carried out to validate the theoretical formulation. Results show that with the interference avoidance criterion based on the multi-frequency RTS/CTS scheme, interference can be rationally avoided. Propagation impacts on the criterion are also discussed and the analysis indicates that the required transmit power of the primary receiver is affected heavily by propagation characteristics.