In convergent access networks, access nodes (composed by optical and wireless components) can serve Base Stations (BSs). In the access node, the wireless receivers are one of the components with high energy consumption level. We can save energy by implementing transmission techniques to receive data in some periods of times, and switching off the wireless receivers the rest of time. However, this strategy will result in increased access delay for packets waiting in the BSs until transmission to the access node. In this paper, we aim at developing a framework for modeling the reception of data by the wireless receivers at the access nodes. We present an algorithm, a numerical formulation and an asymptotic approximation. Comparison between simulation and numerical results is presented and the analysis of results is summarized