Abstract
Mobile sinks (MSs) are capable of collecting data along specified paths in wireless sensor networks (WSNs). They are deployed as a popular alternative for data loggers, to which all nodes have to send sensory data. If MSs' paths (or cycles) are not well determined, it might take a relatively long time for the MSs to make a round trip. Recent research works have proposed methods to determine rendezvous points (RPs) that the MSs must pass by to collect data, with the aim of reducing the data-collection time. Determination of the number of RPs is important, and it is challenging to make ensure that there are sufficient RPs widely located throughout a sensor network, forming a circle along which the MSs can spend limited time traveling. This research presents a method for designing paths and pinpointing RPs for MSs to collect data, as well as determining the next hop to relay data for each sensor node. Instead of reducing the MSs' travel time, the focus of this research is to preserve the energy of all sensor nodes in WSNs. Our method determines the maximum number of RPs such that the MSs can run through each RP's communication range (within a time constraint) without depleting their own energy. The method comprises three main steps. First, we calculate the number of RPs and design the MS path. Second, the exact data-collection points are determined. The last step is to specify the path along which sensory data are relayed to the MS. In our experiments, we simulate two WSNs of different sizes. The results show that our method outperforms the others by 70%-80% in terms of the sensor node uptime, power consumption, MS traveling time and the number of RPs.
Highlights
One important characteristic of a wireless sensor network (WSN) is the continuous communication among a large set of sensor nodes (SNs) that are responsible for collecting various data according to their function, such as detecting objects and motion and sensing temperature, humidity, and flicker [1]–[5]
While previous works are based only on the traveling salesman problems (TSPs) algorithm to determine the traveling path for the Mobile sinks (MSs), we propose a method to reduce the path obtained via TSP to determine data-collection locations, allowing more rendezvous points (RPs) on the path under the same delay-time constraint and reducing the amount of data transmitted by each RP
Algorithm 2 differs from Algorithm 3 in that the former applies TSP to determine circles to specify the visitation sequence of the RPs, while the latter is based on RBR to yield paths with reduced length
Summary
One important characteristic of a wireless sensor network (WSN) is the continuous communication among a large set of sensor nodes (SNs) that are responsible for collecting various data according to their function, such as detecting objects and motion and sensing temperature, humidity, and flicker [1]–[5]. A method for planning MS travel paths is important as it helps determining the rendezvous points (RPs) [23], [24], each of which is an SN selected to be in charge of collecting data from other SNs within its range and relaying the aggregated data to the MSs as they arrive. In consideration of each RP’s communication range and remaining power, the number of SNs within the range, and the distance from the SNs to itself, FLS is adopted to determine how SNs (not selected as RPs) send data to the MS (i.e., whether to send the data via the RP or via a neighboring SN.).
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