Fast rendezvous for cognitive radios by exploiting power leakage at adjacent channels

Cognitive radio is considered as a promising technology that enables dynamic spectrum access and improves spectrum utilization. To bootstrap the communication, rendezvous process is crucial for cognitive radio users to establish communication links among each other. Blind rendezvous is a representative technology for rendezvous purpose without relying on a common control channel. Existing works mainly focus on channel hopping (CH) sequence design to speed up or guarantee users meeting on the same channel, while largely ignored the MAC overhead and PHY layer characteristics. This paper proposes new blind rendezvous protocols that take into account the handshaking overhead and power leakage at adjacent channels. Our basic idea is that a cognitive radio user can infer the transmission at adjacent channels by exploiting adjacent channel power leakage, then it can launch a local channel search to find the other user even when they are not on the same channel initially, thus speeding up the rendezvous process. We analyze the time to rendezvous (TTR) of our protocols with two-user and multi-user settings, and identify the conditions under which our protocols outperform the existing ones. We have conducted extensive simulations to evaluate our protocols. Both analytical and simulation results show that our protocols can significantly decrease the time to rendezvous (TTR) by by 53.5% over the packets decoding based rendezvous.