A Survey of Compressive Data Gathering in WSNs for IoTs

Table 2

Clustering schemes of CDG.

Ref.	CDG scheme	CHs selection	Cluster formation	Main contribution	Year
[17]	Hybrid CDG	-median	Shortest distance	Analyze the optimal number of clusters	2014
[18]	Hybrid CDG	Multicriteria decision problem	Shortest distance	CH selection considering residual energy, distance to BS, and the intra-to-inter distance ratio	2018
[19]	Hybrid CDG	Consider multiple parameters	Shortest distance	CH selection considering residual energy, distance to the sink, node density, and network average energy	2020
[20]	Sparse CDG	Random	Shortest distance	Improve the LEACH protocol to match the sparse CDG and CH selection considering compression ratio	2019
[21]	Plain CDG	Based on spatial location and density of node distribution	Shortest distance	Pay attention to load balance and design even clustering algorithms	2018
[22]	Plain CDG	Optimal solution based on the analytical model	Shortest distance	An analytical model for load balance and optimal number of CHs; the concept of backup CH to reduce the energy consumption caused by rotation of CHs	2019
[23]	Sparse CDG	At the center of evenly divided areas	Shortest distance	Devote to address the hot-spot area problem and propose an annular routing backbone tree	2019
[24]	Sparse CDG	Spatial location	Shortest distance	Propose a hexagonal topology and exploit spatial correlation between sensors’ data; sleep scheduling	2019
[25]	Plain CDG	Location of event source	Shortest distance	Propose a dynamic clustering algorithm considering characteristics of CS theory	2017
[26]	Hybrid CDG	Center of clusters	Based on compressibility	Clustering based on compressive ratios of sensing data, greatly reduce data transmissions	2017
[27–31]	Sparsest and sparse CDG	Not mentioned	Not mentioned	Focus on designing measurement matrices to cut down data transmissions, resist packet loss, or ease implementation in hardware	2014-2020
[32–34]	Sparse CDG	Not mentioned	Not mentioned	Focus on exploiting spatiotemporal correlation by clustering to cut down data transmissions	2014-2019
[32]	Plain CDG	Not mentioned	Not mentioned	Propose a cluster size load balance technique for optimal utilization of CDG	2019