This paper proposes a Duty-Cycle (DC) control method in order to improve the Packet Delivery Ratio (PDR) for IEEE 802. 15. 4-compliant heterogeneous Wireless Sensor Networks (WSNs). https://www.bekindtopets.com/hot-save-Original-German-Pre-WWI-Gewehr-91-S-Artillery-Carbine-by-V-C-Schilling-Serial-7911-b-with-Replaced-Kar-88-Stock-Dated-top-savings/