I. Introduction
Next generation wireless networks (4G) which support high-speed packet data while providing QoS guarantees require flexible and efficient resource management schemes. From an information-theoretic viewpoint, Knopp and Humblet showed that the system capacity is maximized by exploiting inherent multiuser diversity in the wireless channel [1]. The basic idea is to schedule a single user with the best instantaneous channel condition to transmit at any one time. Technology based on this idea has already been implemented in the current 3G systems: High Data Rate (HDR) [2] and high-speed downlink packet access (HSDPA) [3].