Interference Reduction through Multi-hop Transmission in Cognitive Radios

We propose a multi-hop transmission scheme which reduces interference to the primary user in systems with dynamic spectrum access. In the proposed multi-hop transmission scheme, the secondary user's link is transformed into a multi-hop link. The overall path loss reduction obtained via this multi-hop transformation makes it possible to reduce the transmission power of the secondary user without an accompanying throughput loss, which in turn reduces the interference to the primary user. Numerical results show that the proposed multi-hop transmission scheme gives the secondary user more chances to access the primary user's spectrum by reducing the primary user's outage probability while enhancing the secondary user's throughput.