In this paper, we study how the opportunistic relaying can improve both capacity and fairness in cellular network. In wireless network, capacity and fairness are two goals which cannot be achieved simultaneously. To maximize the cell throughput, fairness cannot be guaranteed and vice versa. We show that the achievable average throughput region can be enlarged by using the cooperative relaying. Thus, the enlarged region means that capacity and fairness can be improved at the same time with adequate scheduling algorithm. From the proposed scheduling algorithm, any fairness criterion can be achieved by adjusting control variable. The achieved throughput by opportunistic relaying shows that the max-min fairness does not sacrifice the cell capacity when the relaying channel gains are infinite. From the simulation, we show that the performance improvement gets higher as the user channels become more heterogeneous. Additionally, we propose the feedback algorithm to diminish the amount of the feedback.