8. Conclusions
In this paper, an analysis to characterize the complex interdependence among the basic MAC and routing protocols in IoT was presented. Moreover, a mathematical framework for joint optimization of the MAC and the routing layers parameters was proposed to enhance the existing standards. Specifically, novel metrics that take into account the dynamic behavior of the MAC and routing layers were introduced: R-metric and Q-metric. An extensive comparison of the existing ETX metric with the R-metric, which considers both the level of contention and the protocol parameters, was performed. It was shown that the R-metric achieves high average link reliability. However, it is not able to provide balanced reliability in the network. The Q-metric was proposed, having in mind that a minimum reliability or a maximum delay is required for all the nodes. Extensive experiments, where the proposed metrics were compared to the existing back-pressure routing, supported our mathematical analysis. The inclusion of such an analysis and an experimental study in the current standardization process could be very beneficial in the direction of improving the performance of IoT protocols under realistic conditions.
