Coexistence performance improvement of spectrum sharing system by using multi-hop cooperative relaying

When both a high-priority and a low-priority system share a common frequency band, the low-priority station must sense the presence of the high-priority system, and if required, postpone its transmission or reduce its transmit power to avoid possible interference. To compensate, transmission opportunities of the low-priority system should be ensured as much as possible. Using a transmission scheme ensuring link success with low transmit power, the low-priority system can have more opportunities to transmit. In comparison with direct transmission from the source to the destination, cooperative relaying can reduce the required total transmit power by multi-hop transmission and the diversity effect. Assuming the high-priority system is a type of broadcasting system, and the low-priority system is a distributed wireless network, we propose to apply a multi-hop cooperative relaying scheme to the low-priority multiple links. We show that cooperative relaying successfully provides transmission opportunities for the low-priority system, while guaranteeing the communication quality of the high-priority system.