171 research outputs found
Design Considerations for Low Power Internet Protocols
Over the past 10 years, low-power wireless networks have transitioned to
supporting IPv6 connectivity through 6LoWPAN, a set of standards which specify
how to aggressively compress IPv6 packets over low-power wireless links such as
802.15.4.
We find that different low-power IPv6 stacks are unable to communicate using
6LoWPAN, and therefore IP, due to design tradeoffs between code size and energy
efficiency. We argue that applying traditional protocol design principles to
low-power networks is responsible for these failures, in part because receivers
must accommodate a wide range of senders.
Based on these findings, we propose three design principles for Internet
protocols on low-power networks. These principles are based around the
importance of providing flexible tradeoffs between code size and energy
efficiency. We apply these principles to 6LoWPAN and show that the resulting
design of the protocol provides developers a wide range of tradeoff points
while allowing implementations with different choices to seamlessly
communicate
Surviving sensor network software faults
We describe Neutron, a version of the TinyOS operating system that efficiently recovers from memory safety bugs. Where existing schemes reboot an entire node on an error, Neutron’s compiler and runtime extensions divide programs into recovery units and reboot only the faulting unit. The TinyOS kernel itself is a recovery unit: a kernel safety violation appears to applications as the processor being unavailable for 10–20 milliseconds. Neutron further minimizes safety violation cost by supporting “precious ” state that persists across reboots. Application data, time synchronization state, and routing tables can all be declared as pre-cious. Neutron’s reboot sequence conservatively checks that pre-cious state is not the source of a fault before preserving it. Together, recovery units and precious state allow Neutron to reduce a safety violation’s cost to time synchronization by 94 % and to a routing protocol by 99.5%. Neutron also protects applications from losing data. Neutron provides this recovery on the very limited resources of a tiny, low-power microcontroller
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