In recent years, there have been many studies on integrating a number of heterogeneous wireless networks into one network by establishing standards like IEEE 802.16. For this purpose, the base station (BS) should allocate the appropriate bandwidth to each connection with a network scheduler. In wireless networks, the signal to noise ratio (SNR) changes with time due to many factors such as fading. Hence, we estimate the SNR based oil the error rate reflecting wireless network condition. Using the estimated SNR, we propose a new time slot allocation algorithm so that the proposed algorithm guarantees the delay requirement and full link utilization.