International Journal of Applied Engineering Research ISSN 0973-4562 Volume 13, Number 21 (2018) pp.
14964-14968
                                  © Research India Publications. http://www.ripublication.com
 A Study on Performance Analysis of Distance Estimation RSSI in Wireless
                          Sensor Networks
                                                    S.Satheesh1, Dr.V.Vinoba2
                      1
                        Assistant professor, T.J.S. Engineering College, Chennai-601206, Tamil Nadu, India.
           2
            Assistant professor, K.N. Government Arts College for Women (Autonomous), Thanjavur, Tamil Nadu, India.
Abstract                                                           information on the coordinates of a target placed on the
                                                                   network; in fact, the fields of application are huge. Positioning
Research has shown that the awareness of positions of
                                                                   devices are now part of the daily life of the population.
wireless sensor nodes is a desirable feature for many
applications in Wireless Sensor Networks (WSN). The
performance of analysis distance estimation in WSNs is the
                                                                   LOCALIZATION IN WIRELESS SENSOR NETWORKS
association bordered by the Received Signal Strength
Indication (RSSI) values and distance. The RSSI of nets make       Performance Metrics.
available a practical way of estimating the distance between
nodes because the use of it does not require any additional        Multiple metrics can be used to measure the performance of a
hardware but simply a radio transceiver compared to other          localization technique. It is not enough to observe accuracy
                                                                   only. Referring to the literature and considering the results of
range based models. In this paper, Performance analysis of the
                                                                   our research we provide the following performance measures:
RSSI model that estimates the distance between sensor nodes
                                                                   accuracy, coverage, complexity, scalability, robustness, and
in WSNs is presented. It is shown that the results of this
evaluation can contribute towards obtaining accurate locations     cost. They are mainly connected with economical or technical
of the wireless sensor.                                            constraints such as hardware cost, low battery power, and
                                                                   limited computation capabilities.
Keywords: wireless sensor network, RSSI model, distance
estimation, node.
                                                                   Localization Accuracy.
                                                                   Accuracy is the most important requirement of location
INTRODUCTION                                                       systems. Usually, the mean error between the estimated and
                                                                   the true location of the co-anchor nodes in the network is
In sensor networks, 802.15.4 WPAN the most common
                                                                   adopted as the performance metric. It is defined as follows:
technique used to calculate the distance between two nodes is
the RSSI (Received Signal Strength Indicator) technique
because it has the advantage of not requiring additional                                                     2
hardware and synchronization on nodes. Some studies shows                                1         ‖𝑅𝑥𝑖 −𝑅𝑥𝑗 ‖
                                                                                   LA   = ∑𝑁                     100%
that the RSSI index is fairly unreliable and often produces                              𝑁 𝑖,𝑗=1       𝑅𝑖2
significant errors about the location of the nodes in the
network. In this paper, an approach to the problem of nodes
localization in an outdoor environment is proposed. In order       Where N denotes the number of nodes in a network whose
to obtain more accurate distance estimation, a scenario            location is estimated, LA denotes a localization error, 𝑅𝑥𝑗 the
dependent ranging technique has been adopted. The goodness         true position of the node i in the network, 𝑅𝑥𝑗 is the estimated
of the ranging model is estimated through a comparison with
                                                                   location of the node i (solution of the location system) and 𝑅𝑖
the classic model based on the path-loss long-distance; then
                                                                   is the radio transmission range of the node i. The localization
two localization techniques such as Triangulation and Roc
                                                                   error LE is expressed as a percentage error. It is normalized
RSSI are used in order to test the improvement obtained for
                                                                   with respect to the radio range to allow comparison of results
the estimated positions of nodes within the network.
                                                                   obtained for different sizes and ranges of networks. Usually,
Network evolution has experienced continuous and rapid             centralized location systems give more accurate position
technological development in recent years. The concept of          estimates than distributed ones. The Distributed
networking as a simple connection between terminals has            implementation may involve a loss of information due to an
evolved, becoming increasingly sophisticated and detailed.         incomplete network map and parallel computations.
Wireless Sensor Networks can observe and extract
                                                                   It is obvious that the higher accuracy, the better the system.
information relating to the environment in which they are
                                                                   However, there is often a trade-off between position
placed. Many studies about energy optimization, routing
                                                                   estimation accuracy and other characteristics. Therefore a
information, data representation and more, be situated of
                                                                   compromise between the required accuracy and other
current interest, and the location is a particularly interesting
                                                                   characteristics is needed.
argument today. Attention to this issue is justified by the
increasing demand for more applications dealing with
                                                               14964
    International Journal of Applied Engineering Research ISSN 0973-4562 Volume 13, Number 21 (2018) pp. 14964-14968
                                  © Research India Publications. http://www.ripublication.com
                                                                  dense network, wireless signal channels may become
                                                                  congested and more complex communication infrastructure
                                                                  may be required. The location system can locate the nodes in
                                                                  2- D or 3-D space; some of them can support both 2-D and 3-
                                                                  D spaces. Consolidated systems usually aggregate all
                                                                  measurements and input data at a central unit to carry out
                                                                  processing. By contrast, distributed implementation of
                                                                  localization improves scalability.
                                                                  Definition 1
                                                                  Interval data: For given 𝐼𝑑 ,𝐼𝑅 ∈ 𝑅, and𝐼𝑅 ≥ 𝐼𝑑 , we call the
                                                                  set I = [𝐼𝑑 ,𝐼𝑅 ]={u/ 𝐼𝑑 ≤ 𝑢 ≤ 𝐼𝑅 }interval data, where 𝐼𝑑 is the
                                                                  lower bound of the interval data, and𝐼𝑅 is the upper bound. If
                                                                  𝐼𝑑 =𝐼𝑅 which means the upper and lower bounds are equal, the
                                                                  interval data becomes exact data.
                                                                  Definition 2
                Figure 1. Localization scheme
                                                                  Midpoint and radius of interval data: For a given interval
                                                                  data I = [𝐼𝑑 ,𝐼𝑅 ], let𝑟𝐷 = [𝐼𝑑 − 𝐼𝑅 ] thus, we have
Coverage.                                                                          𝐼𝐷 = 𝐷𝑑 − 𝑅𝐷 , 𝐼𝐷 = 𝐷𝑑 + 𝑅𝐷
The coverage of localization procedures is related to the         We define 𝐷𝑑 and 𝑟𝐷 (𝑟𝐷 ≥ 0) as the midpoint and radius,
deployment area, network density, hardware tools and              respectively, of interval data I. Therefore, we can also express
resources of devices that form a network. Now and then in         the interval data as follows:
effect in outsized, distributed sensor networks when nodes do
not have enough neighboring nodes, unevenly distributed
anchor nodes, or in the case of under the weather equipped                         𝐼𝐷 = 𝐷𝑑 − 𝑅𝐷 , 𝐼𝐷 = 𝐷𝑑 + 𝑅𝐷
devices, problems with localization of the whole linkage may
occur. In such a situation the question is how much of the
network can be localized. In the case of poor results, the only   Because we estimate RSSI-D according to the exact RSSI
option is to increase the number of anchor nodes in a network.    values measured in the RSSI-D procedure, we propose our
                                                                  third definition as the distance between the interval data and
                                                                  the exact data.
Complexity.
                                                                  (3) Distance between the interval data and the exact data:
The complexity of a location system can be attributed to
hardware, software, and operation factors. In general, range-     For given interval data 𝐼𝑋 = 𝐷𝑋 − 𝑅𝑋 , 𝐷𝑋 + 𝑅𝑋 , y=y,
based methods are much complex than range-free techniques         where𝑅𝑋 , 𝐷𝑋 ∈ 𝑅. The distance relationship between the two
and involve hardware complexity. Software complexity              data sets is illustrated in Figure 1. When they are separate
depends on the computing complexity of the positioning            from each other, as shown in Figure2 (a), the minimum
algorithm. In centralized location systems, a central unit        distance is [𝐷𝑋 − 𝑌]-𝑅𝑋 and the maximum distance is [𝐷𝑋 −
calculates the estimated locations due to its powerful            𝑌]+𝑅𝑋 when they are joined, as shown in Figure 2(b), the
processing capability, and sufficient power supply and            minimum distance is 0, and the maximum distance is [𝐷𝑋 −
memory. If calculations are carried out on the sensor node, the   𝑌]-𝑅𝑋 = 2𝑟𝑥 when the interval data contains the exact data, as
effects of complexity could be evident. The Most procedures       shown in Figure 2(c), the minimum distance is 0, and the
that form a sensor network lack strong processing power,          maximum distance is [𝐷𝑋 − 𝑌]+𝑅𝑋 = 2𝑟𝑥 . Therefore, we can
memory and power source, so techniques with low complexity        calculate the maximum distance 𝐷𝑚𝑎𝑥 between X and Y, the
are often preferred.                                              minimum distance 𝐷𝑚𝑖𝑛 and the distance d between the
                                                                  interval data and the exact data as follows:
Scalability.                                                                     𝐷𝑚𝑖𝑛 = max(0, |[𝐷𝑋 − 𝑌]| − 𝑅𝑋 )
The scalability of a location system ensures suitable                                𝐷𝑚𝑎𝑥 = |[𝐷𝑋 − 𝑌]| + 𝑅𝑋
estimation of localization when the network or deployment
                                                                                          D= [𝐷𝑚𝑖𝑛 𝐷𝑚𝑎𝑥 ]
area gets larger. A location system should scale on the
network size (number of nodes) and density, the size of a         As indicated by Equation, the distance between the interval
deployment area and dimensional space. In the case of range-      data and the exact data remains as interval data, which can
based techniques, the location performance degrades when the      comprehensively represent different distance values.
distance between the transmitter and receiver increases. The
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    International Journal of Applied Engineering Research ISSN 0973-4562 Volume 13, Number 21 (2018) pp. 14964-14968
                                  © Research India Publications. http://www.ripublication.com
                                                                On-line distance estimation: During the RSSI-D estimation
                                                                technique, the RSSI charge is restrained by a WSNs (e.g.,
                                                                DD2530 WSN node), and we can estimation the communiqué
                                                                detachment using indeterminate data gathering.
                                                                In the on-line distance estimation component, considering
                                                                poles apart stages of improbability in RSSI values, we accept
                                                                RSSI-D estimation ways and means using both hard and easy-
                                                                going uncertain data gathering methods to increase the
                                                                approximation accuracy.
                                                                The hand-outs of this manuscript are as follows:
                                                                   We propose DEUDC, a RSSI-based communication
                                                                    estimation method, which uses a mapping strategy and an
                                                                    uncertain data clustering method. Unlike sample-based
                                                                    mapping in RADAR and ARIADNE systems, we resort
                                                                    to distribution-based mapping to overcome the
                                                                    uncertainty in RSSI readings.
                                                                    To address the uncertainty in RSSI values, we adopt
                                                                    interval data and statistical information to represent the
                                                                    RSSI distribution characteristic of each distance. In
                                                                    comparison to sample-based mapping, by exploiting
                                                                    distribution-based statistics, our approach can potentially
                                                                    obtain greater improvement in estimation accuracy and
     Figure 2. Distance Relation between Interval Data              efficiency.
                      and Exact Data                               We propose an RSSI-D estimation method in which
                                                                    uncertain data soft and hard clustering algorithms are
                                                                    implemented in order to obtain better estimation accuracy
DISTANCE ESTIMATION IN ONLINE AND OFF-LINE                          with respect to different levels of uncertainty in RSSI.
                                                                   We have evaluated DEUDC using real data sets from
To improve distance estimation accurateness, we have                representative wireless environment. Experimental results
wished-for a RSSI-D approximation technique using interval          show that DEUDC out-performs state-of-art estimation
data gathering, called Distance Estimation using                    methods.
Indeterminate Data Gathering (DEUDC). As given away in
Figure 3, the background of DEUDC is encompassed by an
off-line environment measurement component and an online
distance estimation module.
Off-line environment measurement: We first complete RSSI
illustration measurements at poles apart to improve distance
estimation accurateness, we have wished-for an RSSI-D
approximation technique using interval data gathering, called
Distance Estimation using Indeterminate Data Gathering
(DEUDC). As given away in Figure 3, the background of
DEUDC is encompassed by an off-line environment
measurement component and an online distance estimation
module communiqué points in the wireless communiqué
surroundings. We then deference to the RSSI data intended
for arithmetical computation and model the RSSI distribution
distinguishing in terms of RSSI uncertainties. We can obtain
an RSSI-D charting grounded on this technique.
                                                                    Figure 4 .Impact of Correlation Factor on the RSSI-D
                                                                                     Estimation Method
           Figure 3. The framework of DEUDC.
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                                  © Research India Publications. http://www.ripublication.com
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