title: Superframe Duration Allocation Schemes to Improve the Throughput of Cluster-Tree Wireless Sensor Networks.
abstract: The use ofWireless Sensor Network (WSN) technologies is an attractive option to support wide-scale monitoring applications, such as the ones that can be found in precision agriculture, environmental monitoring and industrial automation. The IEEE 802.15.4/ZigBee cluster-tree topology is a suitable topology to build wide-scale WSNs. Despite some of its known advantages, including timing synchronisation and duty-cycle operation, cluster-tree networks may suffer from severe network congestion problems due to the convergecast pattern of its communication traffic. Therefore, the careful adjustment of transmission opportunities (superframe durations) allocated to the cluster-heads is an important research issue. This paper proposes a set of proportional Superframe Duration Allocation (SDA) schemes, based on well-defined protocol and timing models, and on the message load imposed by child nodes (Load-SDA scheme), or by number of descendant nodes (Nodes-SDA scheme) of each cluster-head. The underlying reasoning is to adequately allocate transmission opportunities (superframe durations) and parametrize buffer sizes, in order to improve the network throughput and avoid typical problems, such as: network congestion, high end-to-end communication delays and discarded messages due to buffer overflows. Simulation assessments show how proposed allocation schemes may clearly improve the operation of wide-scale cluster-tree networks.
authors.affiliation: INEGI/INESC-TEC, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal. ericoleao@ufpi.edu.br.|Department of Computing, Federal University of Piauí, 64049-550 Teresina, Brazil. ericoleao@ufpi.edu.br.
authors.forename: Erico
authors.initials: E
authors.lastname: Leão
authors.affiliation: Department of Automation and Systems, Federal University of Santa Catarina, 88040-900 Florianópolis, Brazil. carlos.montez@ufsc.br.
authors.forename: Carlos
authors.initials: C
authors.lastname: Montez
authors.affiliation: Department of Computing, Federal University of Santa Catarina, 88905-120 Araranguá, Brazil. ricardo.moraes@ufsc.br.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Moraes
authors.affiliation: INEGI/INESC-TEC, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal. pportugal@fe.up.pt.
authors.forename: Paulo
authors.initials: P
authors.lastname: Portugal
authors.affiliation: INEGI/INESC-TEC, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal. pportugal@fe.up.pt.
authors.forename: Francisco
authors.initials: F
authors.lastname: Vasques
keywords: IEEE 802.15.4; ZigBee; buffer overﬂow; cluster-tree; congestion; superframe duration; wide-scale, allocation scheme