Aspects of the disclosure provide a method for selecting a relay node at a first node for transmitting a packet from the first node to a destination node in a wireless sensor network that includes a plurality of nodes. The method can include establishing a transmission angle within which the relay node is preferentially selected, wherein a bounding box surrounding the destination node is between a first side and a second side of the transmission angle, and selecting a second node having a highest remaining energy level among energy levels of neighbor nodes of the first node within the transmission angle to be the relay node. In one example, the candidate nodes for selecting the second node have a remaining energy level above a threshold.