Embedded systems usually lack virtual memory and are vulnerable to memory overflow since they lack a mechanism to detect overflow or use swap space thereafter. We present a method to detect memory overflows using compiler-inserted software run-time checks. Its overheads in run-time and energy are 1.35 and 1.12%, respectively. Detection of overflow allows system-specific remedial action. We also present techniques to grow the stack or heap segment after they overflow, into previously unutilized space, such as dead variables, free holes in the heap, and space freed by compressing live variables. These may avoid the out-of-memory error if the space recovered is enough to complete execution. The reuse methods are able to grow the stack or heap beyond its overflow by an amount that varies widely by application---the amount of recovered space ranges from 0.7 to 93.5% of the combined stack and heap size.

This paper presents a time division multiple access medium access control protocol for wireless sensor/actuator networks implemented with a contention-free message scheduler. A message scheduler is used to determine which message has access to the medium at any time. A set of messages is contention-free if only one message is ready at a time. Otherwise, some other criterion such as priority must be used to resolve contention. In this case, the message scheduler at each node in the network must schedule all messages in order to resolve contention. If the schedule is contention-free however, then each node only schedules the messages that interest it. The key contribution of our contention-free scheduler protocol is scalability. Large wireless sensor/actuator networks may contain hundreds of nodes exchanging thousands of messages. Due to resource constraints it is infeasible that each node schedule every message. Our protocol scales by optimizing each node to schedule only the messages it is interested in.