Wireless Sensor Network Technologies – Agilla, Deluge, Mate
Another key tool is called Deluge which reprograms an entire wireless sensor network by copying a new image into each node’s ROM in an energy/communication efficient way. You can download a copy here.
Boston University came up with an improved version of Deluge which they called NOSY (Network Observation SYstem) which combines Deluge with a variable report rate for adjusting the nodes report rate, remote control so one can program individual nodes, and a watchdog timer for rebooting nodes that haven’t responded within a certain amount of time.
A team at Berkeley came up with an improved cryptography scheme for Deluge. The paper here describes how an “advertisement” message is sent to the network with a hash code that references a second message which also contains a hash code that references the third message, and so on. This way the network can authorize a stream of messages rather than one message at a time.
Mate is a virtual machine designed for sensor networks which uses complex programs in a small amount of code (< 100 bytes). Mate code can be broken up and packetized for distribution throughout the network. It’s a byte code interpreter that encapsulates 24 instructions per packet. Each command is routed to its destination node and processed at the node automatically. Mate uses a stack architecture similar to FORTH which was also a memory efficient structure for handling data and operands. Events fall into three categories: clock timers, message reception, and message send requests. Operands fall into three categories: values, sensor readings, and messages. Future uses of Mate focus on application-specific flavors.
Research into Wireless Sensor Networks reveals a variety of software efforts – some at the node level, and some at the application level, but from this review it’s clear there is a layer of middleware software that will be key to enabling robust applications.