Relay selection method and system for coverage enhancement of multi-hop wireless sensor network

The invention relates to a relay selection method and system for coverage enhancement of a multi-hop wireless sensor network, the multi-hop wireless sensor network comprises a source node, a plurality of relay nodes and a destination node, there is no direct communication path between the source node and the destination node, and the method comprises the following steps: when the source node sends data to the destination node, the relay node sends the data to the destination node; a relay selection rule is triggered, and the relay selection rule is as follows: selecting relay nodes of which the current memory capacity is smaller than an upper limit, and obtaining channel transmission gains between the relay nodes selected at the moment and a source node to form a first set; selecting a relay node of which the current memory capacity is greater than zero, and obtaining channel transmission gains between the relay node selected at the moment and the destination node to form a second set; and obtaining the maxim