End to End Delay and Energy Consumption in a Two Tier Cluster Hierarchical Wireless Sensor Networks

Vicente Casares-Giner,Tito R Vargas H,Dolly Smith Flórez,Tatiana Inés Navas

doi:10.3390/info10040135

Vicente Casares-Giner, Tito R Vargas H + Show 2 more

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https://doi.org/10.3390/info10040135

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Abstract

In this work it is considered a circular Wireless Sensor Networks (WSN) in a planar structure with uniform distribution of the sensors and with a two-level hierarchical topology. At the lower level, a cluster configuration is adopted in which the sensed information is transferred from sensor nodes to a cluster head (CH) using a random access protocol (RAP). At CH level, CHs transfer information, hop-by-hop, ring-by-ring, towards to the sink located at the center of the sensed area using TDMA as MAC protocol. A Markovian model to evaluate the end-to-end (E2E) transfer delay is formulated. In addition to other results such as the well know energy hole problem, the model reveals that for a given radial distance between the CH and the sink, the transfer delay depends on the angular orientation between them. For instance, when two rings of CHs are deployed in the WSN area, the E2E delay of data packets generated at ring 2 and at the “west” side of the sink, is 20% higher than the corresponding E2E delay of data packets generated at ring 2 and at the “east” side of the sink. This asymmetry can be alleviated by rotating from time to time the allocation of temporary slots to CHs in the TDMA communication. Also, the energy consumption is evaluated and the numerical results show that for a WSN with a small coverage area, say a radio of 100 m, the energy saving is more significant when a small number of rings are deployed, perhaps none (a single cluster in which the sink acts as a CH). Conversely, topologies with a large number of rings, say 4 or 5, offer a better energy performance when the service WSN covers a large area, say radial distances greater than 400 m.

Highlights

A Wireless Sensor Network (WSN) consists of hundreds of small and low cost nodes or motes, that are spatially dispersed in a wide area to monitor and capture physical parameters of a target area.Nodes or sensors are powered with small and low cost batteries, and offers several capabilities such as sensing information, data processing and transferring the data packets towards a gateway or central node, named as sink
Some random distribution of the nodes could be considered, such as a 2-D Poisson, for the sake of illustration we assume spatial uniform distribution where the total number of nodes are distributed among the entire WSN area
In the WSN, sensors transmit the sensed information to their cluster head (CH) by using some simple random access protocol (RAP) such as the Frame-Slotted

Summary

Introduction

Nodes or sensors are powered with small and low cost batteries, and offers several capabilities such as sensing information (temperature, humidity, speed of the wind, etc.), data processing (compression, aggregation, ciphering, etc.) and transferring the data packets towards a gateway or central node, named as sink For those purposes sensors are organized in a hierarchical way, using the clustering technique the most common practical solution. The first one is a multi-hop routing scheme, in which the information travels hop-by-hop, from one CH to another CH located in a position closer to the sink, i.e., CHs acts as relay nodes In this first approach, the CHs near the sink process a large traffic load, a situation that leads to a rapid depletion of the energy of those CHs, which results in the so-called problem of the energy hole. These phenomena have been widely discussed quite frequently in the literature, [4,5]

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