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Aiming at reducing the outage probability of primary uses (PU) and obtaining spectrum resource for secondary users (SU), in this paper, we propose an adaptive spectrum sharing protocol for PUs and SUs by efficiently employing the licensed spectrum.In our proposal, SUs can intelligently switch the spectrum sharing strategies between two-path successive relaying (SR) and the opportunity relaying (OR) spectrum sharing protocols.With the cooperation of SUs, the transmission time of PUs can be decreased and the remaining time is allocated for the secondary transmission as a reward.In the SR strategy, with full consideration the channel state between primary transmit (PT) and the secondary transmit (ST) and the interference between STs, two SUs that can achieve largest secondary transmission time are selected to alternatively relay PUs signals to meet the primary target transmission rate requirement.In the OR strategy, an optimal SU that can achieve the largest secondary transmission rate is selected for cooperation to satisfy their target transmission rate.In our SR/OR protocol, the secondary system can access the license spectrum without sensing.Moreover, simulation results show that compared with the conventional cognitive cooperation schemes, the outage performances of both PUs and SUs are improved and the throughput of SUs increases apparently.