As few of resource allocation strategies for relay systems simultaneously consider both subcarrier pairing for multiple users and the requirements of different users

this paper proposes a multiuser subcarrier pairing and power allocation algorithm on the basis of QoS-guaranteed and proportional fairness

which guarantees both the minimum rate requirements of the QoS users and satisfies the criterion of rate proportional fairness among the Best Effort（BE）users.It first allocates the subcarriers of the second hop according to the requirements of different users

then uses the Hungarian pairing algorithm to obtain the optimum pairing of the two-hop subcarriers and finally allocates power by using the similar water-filling algorithm.Simulation results show that the proposed algorithm effectively improves the system throughput while meeting the user requirements for QoS guaranteeing and proportional fairness criterion.