Performance Evaluation of the VB-TDMA Protocol for Long-term Tracking and Monitoring of Mobile Entities in the Outdoors

Abstract

The Virtual Beacon-Time Division Multiple Access (VB-TDMA) communication protocol has been proposed in [12] for a growing class of applications which require GPS tracking of autonomous mobile entities in the outdoors, and the long-term continuous monitoring of their contextual information using wireless sensors. Examples include monitoring animal behaviour in their natural habitat over the annual cycle, tracking shipping containers during their life-cycle of transit, loading/unloading and storage, and the handling of high-value packages during transportation. This paper employs simulations to evaluate the network performance of the VB-TDMA communication protocol in a representative scenario involving wild horses attached with collars, each containing a custom-designed platform with a three-axis accelerometer, a GPS module and ancillary electronics and battery, which uploads wirelessly to static base-stations, its position (sensed thrice an hour) and a summary of its activities between uploads. The simulations benefited from movement models derived from real data obtained from a long-term deployment of the collars on wild horses in the Donana National Park in south-west Spain. Comparisons with other MAC protocols have demonstrated the superior performance of the VB-TDMA protocol over a range of metrics for the representative example. An enhanced version of the VB-TDMA protocol - a multi-hop variant - is introduced for low latency requirements and was simulated for an urban scenario of bicycles fitted with sensors for crowd-sourcing spatio-temporal air quality information along the route of travel which is uploaded to the server when within range of static base-stations, for cases where low latency data upload is a requirement to enable access to the latest air quality information.