Energy balanced routing for latency minimized wireless sensor networks

We present a communication and routing protocol to balance energy consumption among wireless sensor and actuator nodes under the constraint of minimizing end-to-end latency. Minimized and nearly deterministic end-to-end latency allows centralized real time data recording and actuator control. Moreover, defined latency improves security and safety mechanisms to come closer to the trustworthiness of a cable while realizing the advantages of wireless networks. Battery powered or energy harvesting wireless nodes are inevitable to avoid power lines and therefore, we cope with limited energy budgets. In order to balance the communication load among sufficiently supplied nodes, the energy budget is part of the routing path metric. We show that the time domain multiple access scheme is crucial to enable defined latency and improve energy efficiency by avoiding collisions. If the energy distribution among the nodes is known, this novel protocol allows to calculate latency and round-trip time in advance. An asymmetric timing scheme can limit multi-hop latency for either upstream or downstream communication by one superframes (SF) duration. The presented ruleset is able to reconfigure the routing focused on energy constraints of involved nodes.