We designed and implemented a simplified link-level protocol with elastic buffered flow-control and buffered wormhole routing switching, it can support to transmit variable-length packet.

Then I introduce the concepts about level design and make the frame structure of the Proximity link protocol. I also analyze the physical layer, data link layer and the progress of the protocol, etc.

The protocol stack of wireless sensor networks is composed of physical level, logical link control level, network level, transport level and application levels.