PI-based and anti-windup transmission power control for WirelessHART field devices

In the last couple of decades, the industry saw an increase in the number of wireless sensor networks (WSNs) in replacement of the old cabled technology due to lower deployment and maintenance costs. To keep this momentum, those industrial WSN (IWSN) must assure robustness, scalability, low power, and low maintenance, and the network protocol stack is an important piece of this puzzle. One great dilemma faced by IWSN protocols is how to sustain reliable radio links while avoiding draining too much energy from the battery. In this context, Wireless HART (WH) and ISA SP100.11a, for example require the hardware of the nodes to provide multiple power levels for transmission. Unfortunately, those protocols do not provide a standard procedure to choose between those levels. A simple but inefficient solution often employed simply chooses the highest level available. Seeking a better solution, this proposal presents a transmission power control (TPC) methodology that allows energy saving while sustaining the quality of the communication link employing a simple proportional–integral (PI) controller plus anti-windup. The proposed approach does not rely on special TPC-related packets, which is advantageous in comparison with other approaches from the literature by allowing this work to be fully compliant with existing IWSN protocols.