EE-PBC: Energy Efficient Position Based Clustering for Strip Area WSN

Abstract

In this paper we propose an energy efficient position based clustering scheme for WSN that is deployed in a long strip area. The strip area has long width and relatively very small width and is divided into small belt areas. The proposed clustering algorithm selects a cluster-head for each belt area based on its current position in belt area plus distance to the base station and residual energy of the node. The routing between far end nodes and base station is carried out in multi-hop chain based fashion. The simulation results show that our proposed scheme has more stability and consumes less energy than previous schemes.

Full text

EE-PBC: Energy Efficient Position Based Clustering
for Strip Area WSN
M. A. Yaqub†a, A. N. Alvi†b, Syed Hassan Ahmed ‡e, N. Javaid †c, and S. H. Bouk †d
† Dept. of Electrical Engineering, COMSATS Institute of Information Technology, Islamabad, Pakistan.
‡ Kyungpook National University, Daegu, Korea.
{a muhammad_azfar, b naseem_alvi, c nadeemjavaid, d bouk}@comsats.edu.pk, e hassan@monet.knu.ac.kr
Abstract- In this paper we propose an energy efficient position
based clustering scheme for WSN that is deployed in a long strip
area. The strip area has long width and relatively very small
width and is divided into small belt areas. The proposed
clustering algorithm selects a cluster-head for each belt area
based on its current position in belt area plus distance to the base
station and residual energy of the node. The routing between far
end nodes and base station is carried out in multi-hop chain based
fashion. The simulation results show that our proposed scheme
has more stability and consumes less energy than previous
schemes.
I. INTRODUCTION
Wireless sensor network (WSN) is a distributed network
with battery operated nodes that senses and monitors the
deployment area. The energy of network is limited, thus energy
consumption algorithm are strictly abided with. The technical
network challenges associated with WSNs are, self-organizing
algorithm, energy-efficient data aggregation methods, network
lifetime etc. Replacing battery of a sensor node is infeasible.
Therefore, the key challenge is to prolong the network lifetime.
A number of recent researches have addressed these issues [1].
In recent years, WSN are deployed in different strip area
environments such as coal mines, bridges, tunnels, canyons etc.
to monitor the physical parameters of those areas. These areas,
whose length is typically longer and width is often very
narrow, cannot be directly monitored by traditional routing
algorithms such as LEACH [2] and PEGASIS [3].
Position-based Cluster Routing (PBCR) was proposed to
increase the lifetime of this strip area WSN [4]. It provides
better results by dividing the strip area into multiple clusters.
However, it doesn’t ensure efficient energy utilization. The
nodes in strip area WSN usually has to forward data to base
station (BS) in a multi-hop fashion. As the distance to BS is
different, energy consumption of node is unbalance. In this
scenario, data sent by the nodes that are far away from BS
flows through nodes that are near to the BS. In result, the nodes
that are near to the BS are overloaded and consume their
energy instantly and lead to the node failure.
Energy-efficient Position Based Clustering (EE-PBC)
scheme is proposed in this paper, which utilizes the concept of
PBCR and introduces weights to both energy and distance of
the nodes cluster-head selection. The simulations show that the
EE-PBC performs better in terms of network stability and
consumes less energy.
II. ENERGY EFFICIENT POSITION BASED CLUSTERING
The EE-PBC scheme utilizes the Belt-Areas created by
PBCR and to ensure efficient energy usage it assigns weights
to the nodes. The functionality of EE-PBC is divided into four
phases, namely; strip area division, cluster-head election,
cluster-head chain formation and steady-state phase.
A. Strip Area Division Phase
After the random deployment of WSN in a strip area, the
WSN is divided into non-overlapping adjacent belt areas of
same size. The length of belt-shaped region should be less than
or equal to half of node’s communication distance in order to
ensure that every node of the current belt region can
communicate directly with the node in adjacent belt area. The
nodes in a belt region form a cluster and cluster-head is elected
only from the nodes within the current belt-shaped region, as
shown in Fig 1.
B. Cluster-head Election Phase
To fairly elect cluster-head EE-PBC elects cluster-head by
considering both the residual energy of nodes and the distance from
node to BS and it assigns weights to these parameters. The cluster-
head is selected according to the combined weight in each round. The
concrete steps are as follows:
1) Estimate distance dtoBS between sensor node and BS.
As sensor nodes are location unaware, they have no idea about
their geographic location. It is assumed that a node can
estimate mutual distance between two nodes via the strength of
the signal received from another node. At initial stage, BS
broadcasts information message to the whole network. Since
BS is far away from nodes, the normalized value of distance
parameter is calculated using multipath model as follows:
where, davg is the average distance between sensor node and
BS.
Fig. 1 WSN deployed in the strip area that is divided into several equal size
non-overlapping belt regions and cluster-head is elected in each belt region.

2) Energy portion of a node Ep is computed as:
where Ei is the residual energy of node i for round n while Einit
represents the initial energy of node i.
3) The combined weight of node i Wi is computed as:
where w1 and w2 are the weight factors and they must meet the
following criterion:
The exact values of weighting factors are application specific.
4) Compare the different weights of each node and the node with
maximum weight is selected as the leader in this round. The
coefficient flexibility optimizes the leader selection and enables the
algorithm to be applicable to various network situations with diverse
requirements.
The new cluster head will broadcast a packet, containing its
ID and estimated position information, to other nodes in the
cluster. After receiving the packet, neighboring nodes join that
cluster-head and send their data to BS via cluster head.
C. Cluster-head Chain Formation Phase
The cluster-head chain is formed by transmitting the Cluster
Head Information Packet (CHIP) by the cluster-head of a
region to its nearest region via bordering node from region.
The same message is forwarded through all belts until it
reaches the BS, as shown in Fig. 2. After the formation of the
cluster head chain the protocol enters the next phase, steady
state.
D. Steady-State Phase
In this phase data is forwarded from the member nodes to
base station through cluster-heads and relay nodes. The cluster-
head fuses data received from its member nodes and other
clusters, the fused data is forwarded to adjacent cluster-head
nearer to base station. The data is hence forwarded through the
cluster head chain towards the base station.
III. SIMULATION ANALYSIS
The performance of the EE-PBC is compared with previous
schemes. The WSN of 100 randomly deployed nodes in a
500m long and 20m wide strip area where each node with 1J
initial energy is considered in simulation. The size of broadcast
and data packet is 50 and 2000 bytes, respectively. The energy
consumption of medium, amplifier, transceiver circuit and data
aggregation considered for simulation is 13pJ/b, 0,003pJ/b,
10nJ and 5nJ, respectively.
Network stability and average energy consumption per node
is shown in Fig. 3 and 4. It is evident from the results that
initial node in EE-PBC dies almost after 3000 rounds later and
the average energy consumption per node is far more less than
the previous schemes.
IV. CONCLUSION
The proposed EE-PBC scheme considers weighted distance
and residual energy information to elect cluster-head in strip
area deployed WSN. The simulation results validate that EE-
PBC consumes less average energy per node and is more stable
than the previous schemes.
ACKNOWLEDGMENT
The preferred spelling of the word “acknowledgment” in
America is without an “e” after the “g.” Try to avoid the
stilted expression, “One of us (R. B. G.) thanks …” Instead, try
“R.B.G. thanks …”
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Fig. 2 Cluster-head chain formation.
Fig. 3 Network Stability.
Fig. 4 Average energy consumption per node