In this paper, we propose an opportunistic downlink scheduling scheme that exploits multiuser diversity in a wireless network with threshold-based limited feedback. We assume that each user has its own ergodic rate requirement. The design objective of our scheme is to determine the values of thresholds with which heterogeneous ergodic rate requirements of all users are satisfied. In our analysis, we present a formula to check the feasibility of given ergodic rate requirements, and then obtain the feasible thresholds that realize them. We also obtain the optimal thresholds that maximize the ergodic sum-rate of the network while guaranteeing the ergodic rate requirements. Through numerical studies and simulations, we show the usefulness of our scheme and analysis.