LINKORD: link ordering-based data gathering protocol for wireless sensor networks

With respect to the multi-hop communication pattern of wireless sensor networks, all the nodes should establish multi-hop paths towards a common data gathering point to provide a data gathering service for the underlying applications. Although data gathering protocols provide a simple service, these protocols suffer from poor performance in practice due to the power constraints of low-power sensor nodes and unreliability of wireless links. Existing data gathering protocols rely on the ETX metric to find high-throughput paths through assuming there is an infinite number of transmission attempts at the link layer for delivering a single packet over every link. However, in practice the link layer provides a bounded number of transmissions per packet over individual links. Therefore, employing existing data gathering protocols in these situations may result in the construction of the paths that require more than maximum number of provided link layer transmissions for delivering a single packet over each link. In this regard, we propose a path cost function which considers the limitation on the number of provided link layer transmissions and relative position of the links along the paths according to their data transmission probability. Furthermore, we introduce a data gathering protocol which uses the proposed path cost function to construct high-throughput paths. Moreover, this protocol employs a newly designed congestion control mechanism during the data transmission process to provide energy-efficient and high-throughput data delivery. The simulation results show that, the proposed protocol improves data delivery ratio by 70 % and network goodput by 80 %, while it reduces the consumed energy for data delivery by 50 % compared to the default data gathering protocol of TinyOS.