Sink mobility schemes for data extraction in large scale WSNs under single or zero hop data forwarding

A mobile sink is widely considered to facilitate the data collection from energy constrained sensor fields, by having the sink come close to the sensors and conserving precious sensor node energy. The effectiveness of such a data collection approach can be measured in terms of the sensor energy conserved and the time required to collect the sensor data from the field (or, equivalently, the length of the trajectory implemented by the mobile sink). In this paper we explore two important dimensions in the design of mobile sink-based data collection schemes. One dimension refers to how close to the sensor nodes the sink moves to, to collect the data, which impacts on the transmission energy expenditure by the sensor node. The other dimension refers to the way the sink moves through the sensor field, to collect the data, which impacts on the delay in collecting the data. To capture the first dimension, the 0-hop and 1-hop data collection schemes are considered and studied; at the same time, two ”extreme” approaches to the sink mobility process are considered: a (topology unaware) random walk-based sink mobility scheme and a (topology aware, optimal) deterministic sink mobility scheme. Through the analytic and simulative study presented in this paper, an understanding of the level of the trade-offs involved between the energy spent by the sensor nodes and the delay in completing the data collection process is obtained.