Recently, it has been received in the community that the link reliability is strongly related to RSSI (or SINR) and the external interference makes it unpredictable, but the unpredictability has not been fully explained yet. In order to examine the causes of the unpredictable link state, we first configured an empirical testbed, performed a measurement study, and observed that the link reliability actually depends on an intra-frame SINR distribution. We also discovered that a RSSI (or SINR) value is not always a good indicator to estimate the link state. Based on these results, we propose a modeling framework for estimating the link state in the presence of the wireless interference. We vision that the framework can be used for developing link-aware protocols to achieve their optimal performance in a hostile wireless environment.