opportunities to determine the effectiveness of …wireless sensor network. the design and...
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International Journal “Information Theories and Applications”, Vol. 25, Number 3, © 2018
255
OPPORTUNITIES TO DETERMINE THE EFFECTIVENESS OF SENSOR NETWORKS
Filip Tsvetanov, Ivanka Georgieva
Abstract: The actuality of WSN determined by the concept of intellectualization of various objects
including homes, offices, buildings, industrial processes, etc. Sensor networks are distributed networks
built of tiny sensor nodes exchanging information over wireless channels with the ability to record data
on all parameters that is been asked to monitor and transmit measurement data to a base station or
nodes to retransmit signals. The design and deployment of sensor networks require solving a variety of
complex problems that are specific to each sensor network. Therefore, sensor networks have
requirements for effectiveness in the implementation of the objectives in their design. Lead research
shows that currently there is no method for comprehensive evaluation of the efficiency of sensor
networks. In this paper is proposed an algorithm for determining the effectiveness of the sensor network
according to specific criteria
Keywords: sensor networks, effectiveness, algorithms, sensor notes.
ITHEA Keywords: C.2.Computer Communication networks, C.2.1.Network architecture and design.
Introduction
Sensor networks is distributed, self-organizing systems of miniature autonomous wireless sensing
nodes united by a radio channel and which can connect to global computer networks. The area of
sensor network coverage can range from several meters to several kilometers, thanks to the ability to
retransmit messages from one node to another. Sensors measure and transmit data on temperature,
pressure, humidity, light, vibration, and more. The choice of sensors determines the functionality of the
wireless sensor network. The design and deployment of sensor networks require solving a variety of
complex problems that are specific to each sensor network. For this reason, sensory networks are
subject to performance requirements in terms of achieving the objectives set when designing them.
The effectiveness of the sensor network is the ability to fulfill a particular purpose under certain
conditions and with a certain quality. Efficiency metrics characterize the adaptability of the sensor
network to perform the set tasks and are a summary indicator of the optimal functioning of the network.
The conducted literature study shows that the performance of sensor networks is an ongoing research
problem that has come to the attention of many researchers, both from the academic community and
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256
the industry. The current research focused on determining the performance of basic single parameters
of sensor networks. Comprehensive evaluation of the sensory network performance recommended by
the expert judgment method.
Summary of Contributions. In the present work, we propose one algorithm for determining the efficiency
of sensor networks by collective parameters. The algorithm involves developing a model of the sensed
sensor network, depending on the formulated collective performance parameters.
Characteristics of sensor networks, influencing efficiency:
1) Connected to the design features of the sensors
Sensor nodes have resource constraints: limited energy, limited communication and computational
capabilities, and limited memory. The choice of the sensor determines the functionality of WSN. The
wireless sensors (WS) used in the network are a set of the sensors or sensors for different quantities,
an interface module, a control unit (Microcontroller, Microcontroller Unit, Processor), Memory and T / R
Transceiver (Figure 1).
Figure 1. The architecture of wireless sensor
For successful connection in WSN, it is necessary for WS to have a small DC consumption, for which it
is first necessary to use appropriate integrated circuits in the blocks. In addition, WS will only be on a
regular basis for a short period to carry out the measurement and store the data in its memory as well
Sensor
Adjustment and configuration
Control Functionals
Signal conditioningand Driver
Analog Gain
Amplifier
Interface module
DSPADC
Procesor
Display Memory
Communications
Battery
Power Converter
Power unit
Algorithm
Operating system
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as broadcast it. The sensor is in the Sleep Mode for the rest of the time, where it consumes a minimum
electricity. It is the time of inclusion in a call (Immediancy) does not exceed a few ms.
2) Associated with the choice of communication range and frequency of measurement
When selecting a WSN range for a particular application, it should be borne in mind that lower
frequency operation is suitable for premises with large mobile and stationary objects (machines, tanks,
vehicles, etc.) and in the presence of dirt in the air with fine particles. At the same time, the use of higher
frequency bands means remoteness from industrial interference and therefore the ability to operate with
lower radiated power and lower DC consumption. Depending on the measurement frequency, WS
operates with Periodic Sampling or Even-Driven, which done only when the controlled value passes a
certain value.
3) Associated with the topology of the sensor network
The simplest type of networks is Star Network. Their name followed by spatial location (Fig. 2a) of the
end nodes (End Point, Edge Node, Node, Device) D about the control node (Gateway, Base Station,
Bridge, Controller, PAN Coordinator) C. The latter is a specialized data exchange node, but it can also
be a personal or pocket PC (PDA). By managing the operation of D, exchanging sensor data and
relaying the collected data to other networks. For star networks, the Single-Hop System - Sensor data
transferred to the receiver with a single "jump", the structure of the Point-to-Multipoint type. The main
advantage of these networks is that they have the smallest DC consumption of all WSNs.
The most common are the WSN Mesh Network. Their structure is of the Multipoint-to-Multipoint type
(Figure 2.b). They also have a control node C, and the remaining nodes in the network are end-R, in
addition to working as sensors, can be and routers (Router, Mesh Node, Coordinator), by exchanging
data through C and to each other. This means that the connection between two R-type nodes can be
immediate, but much more often goes through other nodes. Thus, the data requires several "jump" from
node to node until they reach the coordinator. This indicates that this type of network is a Multi-Hop
System. In addition, several routes between two nodes are possible, and the network programming
selects the shortest of them. In the case of a damaged R or major interference on the nearest router,
another router is automatically been chosen, which is why they are self-healing networks (Self-Repairing
Network). When switching WS on and off, and in the presence of moving WS in it (as in GSM networks),
it also changes routes, which makes it a self-configuring network. Self-organization allows the network
to automatically recognize and activate each new node.
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D
D D
D
DD
C
a)
R
R
R R
R
R
C
b)
R
R
RR
R
R
C
D
D
D
D
D
D
c)
Figure 2.Topology of wireless sensor networks
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The third type of network structures of WSN is Point-to-Point-to-Point or Peer-to-Peer. Unlike the Star
WSN, where the entire control is concentrated in the C-node, the control distributed between all nodes
and therefore called distributed (Distributed Control). The P2P networks cover a significantly larger area
(theoretically unlimited) than the star type. Each sensor network, regardless of which type has only one
control device (coordinator). The main task of the coordinator is to set parameters and create a network,
to select the basic radio channel according to the unique network identifier. The coordinator is the most
complex device in the network, has the most memory and great power consumption compared to other
network devices. Routers used to extend network coverage because they are capable of performing
repeater functions between devices located away from each other. Another feature of sensor networks
in studying their effectiveness is the number of main routers (the main hop note or routers). By this
criterion, they can divided into two groups: a single hop node - a powerful sensor with a transmitter for
transmitting the signal a base station and multiple hop nodes, but also to collect data from other nodes.
Related work:
[Tuzhilkin et al, 2012] proposes an approach for complex multi-criterion assessment of the sensory
network efficiency through the expert judgment method. In this case, determining the performance of an
entire sensor network is a complex multi-criterion task, which is very important to prioritize the indicators
(sort by importance). These studies used in cases where the requested information cannot obtained
experimentally. The effectiveness of individual parameters such as loss tolerance investigated by a
stimulation study method with the Cooja simulator packages from [Vasco, 2016].
In Diwa et al., 2017, an effective approach is proposed through an individual parameter to increase the
energy efficiency of WSM, resulting in research suggesting sensor clustering algorithms that prolong
network life by avoiding node communication with a base station over long distances.
[Tsvetanov et.al. 2014] proposed model allowed assessing the effectiveness of the communication
between nodes in a WSN based on Dijkstra's algorithm and the algorithm of efficiency. Simulation
studies conducted in various network parameters. Based on the interpretation of the results we make
the following summary:
[Chiasserini et al., 2004] has developed a Mark Sensor Network Model to check the system's
performance in terms of power consumption, network capacity and data delivery delay.
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Sensor Network Performance Metrics:
Despite the high requirements in terms of operation, each WSM must possess a number of functional
metrics that must followed in order to solve the task. We believe that an important condition for obtaining
a reasonably efficient operation of the sensor networks is correctly and accurately define the parameters
for the respective network. The performance metric is a quantitative feature of the network considered in
relation to certain conditions of its operation. Each wireless network has an individual set of parameters
defined by the location of the devices and their technical characteristics, network-operating conditions
(terrain, meteorological condition, etc.). In order to achieve this purpose, we consider the classification
of metrics as Individual and Collective [Vasco, 2016] as closest to our understanding.
Individual metrics refer only to one node and do not give any idea of the behavior of the network as a
whole. Individual metrics are essential when removing errors in a specific sensor or evaluating its
specific results. In addition, constant tracking of individual metrics, including computation and
transmission, leads to depletion the energy of the wireless nodes and reduced their life.
When calculating metrics based on collective parameters, a pre-defined part of the network or even the
entire network is included. For example, a data collection request for collective packet loss will be the
sum of the losses of individual bundles from all sensors that send data associated with a specific event.
Collective delay of the difference between the moment of receiving the data and the time when the last
event packet from all target nodes arrived at the coordinator. Collective parameters for network
performance research were discussed in [Vasco, 2016] and [Sohraby, 2007].
We believe that since WSN are different from traditional communication networks, and therefore
different performance measures may require evaluate them. Therefore, the collective parameters
evaluating the performance of the network as a whole must include all the necessary requirements that
affect the life of the network, the speed, quality and efficiency of packets traveling thru the network.
These are parameters such as:
― Delay Tolerance - defines the time limits for the delay of packet delivery in a network;
― Loss Tolerance - defines limitations on data transmission losses on the network;
― Capacity - measures the total network capacity for data transmission;
― Reliability - the ratio of successfully received packets over the total number of packets
transmitted;
― Energy Efficiency – the number of packets that can be transmitted successfully using a unit of
energy;
― Criticality - determines how the network deals with traffic priorities;
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― Fault Tolerance of the error - determines the tolerance of the network to permanent or
temporary node failure.
― System lifetime- can defined in several ways: (a) the duration of time until some node depletes
all its energy, or (b) the duration of time until the QoS of applications cannot guaranteed; or (c)
the duration of time until the network has disjoined.
― Coverage- defined as the ratio of the monitored space to the entire space.
Modeling of sensor networks
The performance of a sensor network should considered at the design stage of the network. An
important stage in the design of sensor networks is the development of models, depending on the
objectives set. Formulated above metrics to determine the parameters for collective evaluation of the
effectiveness can applied successfully in the development of WSN. Depending on the objective and the
expected effectiveness, it recommended developing the following models [Sohraby, 2007], [Tsvetanov,
2013]:
― Traffic model - greatly influences protocol design and affects performance. The four models and
the related performance traffic patterns in WSN, event-based delivery, continuous delivery,
query-based delivery, and hybrid delivery.
― Energy models, radiocommunication function of the sensors is the most energy-intensive
function in the node. Including Model for Sensing, Model for Communication, Model for
Computation.
― Node Model to save energy, a common approach is to allow the nodes to sleep when they do
not need transmission or receipt. This behavior accepted to model in two states of the sensors:
active (A) and sleep (S).
― Network Models - The access to the data transmission channel is controlled and distributed by
MAC protocols, as in a decentralized environment a packet collision may occur in the channel,
which is why it is important that the data be successfully transmitted over time transmitted
successfully in a time slot (routing Model). The network model used to model the routing policy
and determine the average bit rate between nodes. This routing policy determines when to
transmit data to the next hop, for which purpose the sensor node selects the one with a single
node that will lead to the lowest power consumption.
― Interference model, to calculate a successful transmission probability in the time slot, for
example in a CSMA / CA mechanism with handshaking.
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― Closed loop - system model including the sensor node model, the MAC protocol model, and the
routing model. This model provides a comprehensive assessment of the effectiveness of WSN.
An algorithm for determining the performance of sensor networks by collective parameters:
Based on the acquired own experience of research on the effectiveness of individual parameters of
sensor networks [Tsvetanov, Radev 2013], [Tsvetanov, 2013], [Tsvetanov, 2014], research into literary
sources and the understanding that WSN modeling is a useful tool for evaluating WSN performance.
The authors offer a scientifically grounded approach to determining sensor network performance
through collective parameters including the following steps:
First Step. Analysis of the assigned task and purpose of the sensor network and determining the
type of efficiency.
The efficiency of a wireless network is critical to its operation and assess the quality of
communication between nodes in the network. It is known that the energy for communication between
nodes is large, which is why the method of data transmission between nodes is essential to network
performance. Let's look at wireless network with N nodes, which is modeled as a graph G = (V = {1, ...
N}), with N peak of Count, where in the 2D space each peak i is identified by a set of coordinates pi =
(xi, yi ). It is assumed that Euclidean length di,j between two peaks i, j ∈ V is the physical distance
between nodes, which is represented as a matrix E. It assumed that the global efficiency and local
wireless network could quantified. It assumed that global and local efficiency indicators normalized on a
scale from zero to one. Zero has the lowest efficiency, and with one the highest efficiency of the sensor
network. [Tsvetanov. F.]. To achieve the objectives of the task, we assume that the global network
performance needs to be determined. The global or overall efficiency of a WSN from an assessment of
the Eglob communication can be determined according to the dependency:
Е = 1− 1 1 , (1)
Where, dij is the Euclidean length between the pairs of nodes i и j, located within radio
communication range.
Step Two. Choosing a model for sensor networks
Depending on the purpose of the sensor network, it is necessary to determine the type of model,
under section "Modeling of sensor network." For example, if the claim is a requirement for the
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effectiveness of the communication between the sensors nodes can be designed energy model that
takes into account all of the specific parameters for the conduct of the process, the hardware
characteristics by power consumption per node:
Е , = Е + + + + , (2)
Where Еrx it is the energy of receiving data, Etx is the energy to send data, Elisten is the energy to
listen to the channel, Eedle It is energy in standby mode for data transmission, Esleep is the energy of
sleep on a device.
To measure energy consumption and generate residual energy in a sensor, determine the
duration Δt between two time intervals t1 and t2 between which the energy consumption of each sensor
is measured
∆ = − (3)
It assumed that the remaining battery power of each node defined as Е , = , − ∆ − Е , ∆ , (4)
Where ∆ = ∆ . (5)
Step Three. Determine the type of performance metrics for each model. Metrics must be
measurable. Analytical determination of the selected metrics and determination of their limit values and
loading in the survey model. All simulation parameters of the sensor network are included as: network
area in meters in the two-dimensional space on the axes x and y; total number of nodes; position control
of the control node, communication range of the devices; initialization power values for reception and
data transmission, sleep, idling of network devices, topology modeling, etc.
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Step Four. A simulation program is developed and simulations conducted in different network
exploitation scenarios. In these studies can get a visual idea of working capacity of the network (Figure
3) energy resources of each of the sensors in the network (Figure 4.) to determine the global efficiency.
Figure 3. Simulation scenario for the Study of sensor network
Figure 4. Sensors energy resources depending on their communication
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The global efficiency increased with increasing the range of the radio node, due to a reduction in the
number of intermediate transfers of data, the number of jumps and reduced length of the route;
Figure 5. The efficiency of communication at N = 50, depending on the radio communication
range and the number of connections
Global efficiency is higher in networks having more connections between the devices, which may be
due to allowing a higher number of alternate routes to provide an energy efficient communication
between any two units in the network.
Step Five. Analysis of Research Results. If the effectiveness of the research parameter or
collective parameters is satisfactory, proceed to practical implementation and network construction.
If it is not satisfactory, proceed to the selection of step two to determine additional parameters.
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Conclusion
The presented approach for determining the performance of sensor networks is the result of several
years of authors' work. The paper analyzes the constructional and technological characteristics of the
sensor networks that influence their efficiency, as well as the indicators that are important for obtaining
and evaluating their effectiveness. A summary algorithm for assessing the performance of sensor
networks proposed based on the authors' experience in studying the individual sensor network
parameters and understanding that the collective parameters give a complete indication of the
effectiveness of the designed sensor network. The algorithm for determining network efficiency includes
an in-depth analysis of the objective and possible approaches to solving it. An important challenge for
getting a science-based response is the right choice of model and chosen modeling technology.
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Authors' Information
Filip Tsvetanov – South-West University, Blagoevgrad, Bulgaria, Assoc. Prof. of
Communication and Computer Engineering: e-mail: [email protected]
Major Fields of Scientific Research: Sensors networks, networks security,
efficiency low speed networks.
Ivanka Georgieva – South –West University, Blagoevgrad, Bulgaria, Assoc. Prof.
of Department of electrotechnic, electronic and automation, e-mail:
Major Fields of Scientific Research: Sensors networks, industrial networks, the
efficiency of networks, industrial application of Internet of Thinks.