Analysis of new strategies for WSN real-time configuration

The configuration time in a Wireless Sensor network is normally not a concern, since the time required is very low, compared to the dynamics of the traffic exchanged. There are however situations where a low configuration time can have a real influence on the usability of an application or on the achievable performance, for example the superframe can be dynamically adjusted depending on the actual requirements and the number of active nodes in a certain moment. This approach has been developed for the FACTOTHUMS application scenario, with the purpose of having a localization network that can be dynamically reconfigured, depending on the position of the node being tracked, allowing to select the best anchor nodes in each area. The number of total anchor nodes in the monitoring area can then be increased without disrupting the real-time performance of the WSN, since the active anchor nodes number can be adjusted, depending on latency and accuracy requirements. The use interaction dynamics are not considered in this report, notwithstanding they represent a very important aspect, that shall not be underestimated in the final application. This report presents a comparison between two simple configuration strategies, one inspired by the last revision of the IEEE 802.15.4 standard [1], called Online Configuration, and another inspired by a recent amendment to the same standard, IEEE 802.15.4e [2], in particular the LLDN operating mode; this is called Offline Configuration. The tradeoff, as will emerge in this report is between continuous availability of application data transmission (uptime) and configuration time. These two simplified configuration methods have been defined because of their simplicity of simulation; however, they represent the access method present in real implementations, respectively the IEEE 802.15.4 and the FACTOTHUMS implementation, so the advantages and disadvantages of the two cases can still be analyzed.