Simply because the OSI model has been effective for wired networks, the communications within the wireless sensor networks (WSN) since its appearance are ensured by a layer model, inspired by the OSI model. Since, protocols are designed independently in this model, metrics involved in several layers can be affected. Energy consumption and fast data aggregation are among the most important metrics, impacted by both the routing protocol in the network layer and the MAC protocol in the data link layer. Cross-layer, an emerging design that attempts to expand the interactions in the protocol stack has shown an improvement in the overall performance of such networks. In this context, in order to achieve energy efficiency and fast data aggregation, and since the protocols of the MAC sub-layer and the network layer have a direct effect on these two metrics, we propose Efficient-Depth-ReLO, a centralized cross-layer approach between these two layers. This approach aims to build a TDMA scheduling by using the routing tree information. On the other hand, the proposed approach solves efficiently the hidden node problem. The results of extensive simulations show that the proposed approach performs better than similar existing works in terms of energy consumption and communication latency.