arXiv:1307.7111v1 [cs.NI] 26 Jul 2013
LPCH and UDLPCH: Location-aware
Routing Techniques in WSNs
, N. Javaid
, M. J. Khan
, Y. Ahmad
, M. H. Zubair
, S. A. Shah
Dept of Electrical Engineering, COMSATS Institute of IT, Islamabad, Pakistan.
University of Oulu, Oulu, Finland.
CAST, COMSATS Institute of IT, Islamabad, Pakistan.
Abstract—Wireless sensor nodes along with Base Station (BS)
constitute a Wireless Sensor Network (WSN). Nodes comprise
of tiny power battery. Nodes sense the data and send it to
BS. WSNs need protocol for efﬁcient energy consumption of
the network. In direct transmission and minimum transmission
energy routing protocols, energy consumption is not well dis-
tributed. However, LEACH (Low-Energy Adaptive Clustering
Hierarchy) is a clustering protocol; randomly selects the Cluster
Heads (CHs) in each round. However, random selection of
CHs does not guarantee efﬁcient energy consumption of the
network. Therefore, we proposed new clustering techniques in
routing protocols, Location-aware Permanent CH (LPCH) and
User Deﬁned Location-aware Permanent CH (UDLPCH). In both
protocols, network ﬁeld is physically divided in to two regions,
equal number of nodes are randomly deployed in each region.
In LPCH, number of CHs are selected by LEACH algorithm in
ﬁrst round. However in UDLPCH, equal and optimum number
of CHs are selected in each region, throughout the network life
time number of CHs are remain same. Simulation results show
that stability period and throughput of LPCH is greater than
LEACH, stability period and throughput of UDLPCH is greater
Index Terms—Location-aware, Permanent, Cluster, LEACH,
LPCH and UDLPCH.
WSNs connect end users through BS or sink directly to
sensor network and to provide information, according to the
user need or demand . WSN can be composed of hundreds
or more sensor nodes. Which are randomly deployed inside the
area of interest or very close to it and a BS or sink. Nodes
sense the data and send their report toward sink. Stability
period of WSN are limited. In order to prolong the stability
period of WSN many routing protocols like , , , etc
are proposed and many new energy-efﬁcient routing protocols
must be designed. Classical approaches like direct transmis-
sion and minimum transmission energy do not guarantee well
balance distribution of the energy load among nodes of sensors
network . In direct transmission, every node directly sends
their data to BS, therefor far away nodes consume greater
energy in sending data to BS and die quickly. However in
minimum transmission energy, far away nodes send the data
to BS through intermediate nodes, so nodes that are near to
BS die quickly. A solution proposed is of adaptive clustering
algorithm called LEACH. In LEACH, routing operation is
divided in to rounds. In each round randomly CHs are selected,
CHs then form clusters, and in each cluster there are cluster
members and a CH. Each cluster member node sense the data
and send to CH. CH receives the data, aggregate it and sends to
BS. However in LEACH there is no optimum number of CHs
in each round, also randomly selecting CHs makes different
size of cluster; number of nodes in each cluster are vary. CH
of large size cluster consume greater energy and vice versa.
Therefore sensor nodes of network does not consume balance
Our contribution: In this paper, sink is not energy limited.
We divide the network operation in to rounds. To improve
the efﬁciency of WSN, we proposed two new routing pro-
tocols: LPCH and UDLPCH. These proposed protocols are
clustering based techniques. In LPCH, we divide network
ﬁeld physically into two regions. Equal number of nodes are
randomly deployed in each region. In ﬁrst round, CHs are
selected according to LEACH algorithm. From second round
to last round, number of CHs remain same as in ﬁrst round.
This prolongs stability period and also greater throughput
is obtained. UDLPCH follow the same thoughts to LPCH
except, ﬁrst round. In ﬁrst round user deﬁne optimal number
of CHs in each region. In case of UDLPCH stability period
and throughput obtained is greater than LPCH.
II. RELATED WORK
W.Heinzelman et al.  introduce a hierarchical clustering
algorithm for sensor networks, called LEACH.
W.Heinzelman et al.  gives an extension of LEACH
protocol uses centralized cluster formation algorithm for the
formation of cluster. The algorithm execution start from the
BS when the BS ﬁrst receives message of all the information
about each node regarding their function and energy level then
it runs the algorithm for formation of CH and cluster. However,
LEACH-C is not feasible for large networks because the nodes
which are far away will have difﬁculty in sending their status
W.Heinzelman et. al  use the idea of the clusters remain
ﬁxed and only rotate the CH with in the cluster this will
increase the throughput and also saves the energy. However,
the disadvantage is that the new nodes cannot be added to the
Yun Li et. al  improve CH selection procedure. It makes
residual energy of node as the main metric which decides
whether the nodes turn into CH or not after ﬁrst round. In
E-LEACH, ﬁrst round have same probability to become CH,
in next round the residual energy of each node is different
after one round communication and taken into account for the
selection of CHs. That means node have more energy will
become CH rather than node with less energy.
Dissertation, Hang Zhou, Zhe Jiang and Mo Xiaoyan 
introduce a multi-hop routing protocol for WSNs called M-
LEACH. M-LEACH protocol select optional path between
CHs and BS through other CHs and use these CHs as a
relay station to transmit data over through them. First multi-
hop communication is adopted among CHs then, according
to the selected optional path, these CHs transmit data to the
corresponding CH which is nearest to BS. Finally CH send
data to BS.
Haosong Gou and Younghwan Yoo  improve network
coverage by dividing network area into subareas known as
partition-LEACH. In each subarea the head node is elected
to receive data from other nodes with in subarea and then
forwarded to BS. In partition-LEACH every node send its
location and residual energy information to BS during network
initialization step. The sink divide the network area into
subareas according to optimal number of CH expected.
Localization problem is commonly addressed by many re-
searchers. In localization, network eld area is logically divided
into sub areas -  to overcome the problem. Random
deployment of nodes may cause overlapping problem, i.e. two
nodes deployed in the same area may sense same location and
some area may not be sensed . In  authors proposed
energy consumption model and tried to nd energy hole in
cluster based routing protocols. They identied different areas
of the network in which energy is consumed more than other
areas. Similarly, authors in  proposed an energy hole
removing mechanism to increase the network lifetime.
Authors in  proposed EAST protocol for WSNs. In
this protocol, the temperature aware link quality estimation
is done via open looping feedback and closed loop feedback
process is used to reduce overhead of control packets. In 
Advanced LEACH routing protocol for heterogeneous WSNs
is proposed. Basically, this protocol uses static clustering i.e.
at ﬁrst the network area is divided into sub areas, each one
acting as a cluster. Then, in each static cluster CH is selected
according to the criteria set by LEACH.
Authors in  conducted a comprehensive survey based
on routing protocols for WSNs. In this survey, they classiﬁed
routing protocols into different categories and explored some
common issues related to LEACH protocol. Moreover, how
extended versions of LEACH tackled the respective issues are
also discussed in this survey paper.
In current research body of WSN many routing protocols
are proposed. LEACH is one of the very ﬁrst routing protocols.
In LEACH, BS selects CHs randomly. However it can be
improved in many aspects. Firstly, LEACH does not guarantee
optimum number of CHs (n × p) in each round of epoch,
where n is total number of nodes and p is probability of
optimal number of CHs. Secondly, CHs are selected randomly,
Fig. 1. Comparison of (d
) and (d
so clusters formed are of different sizes. Therefore CH in a
large size cluster (greater number of member nodes) consumes
greater energy. Thirdly, member node sends data to CH, even
if its distance from BS is less than its distance from CH, i.e,
, as can be seen in the Fig.1.
In our proposed protocols LPCH and UDLPCH, we enhance
the LEACH protocol. Following the theme of  and ,
we divide network ﬁeld physically into two regions. In LPCH,
we select CHs according to LEACH algorithm where in
UDLPCH, we select optimum number of CHs in each region
in ﬁrst round. Our proposed protocols LPCH and UDLPCH
focus on controlling: cluster size, maintain number of CHs
same in all rounds, distance between member nodes and CHs.
which results in efﬁcient energy consumption. Hence stability
period and throughput of WSN is improved.
IV. PROPOSED PROTOCOL
In this section we discuss the network model for proposed
protocols: LPCH and UDLPCH. We also discuss these proto-
cols in detail.
A. Network Model
We divide the network ﬁeld physically into two regions, and
equal number of nodes are randomly deployed in each region.
The BS is in the center of the ﬁeld with coordinates (50, 50)
shown in Fig.2. All nodes in the network are homogeneous
(same energy nodes). The BS is not energy limited. This model
uses a location-aware clustering scheme. In location-aware
scheme, BS is location aware of all nodes in the ﬁeld. Each
cluster has a CH which collect data from cluster members,
aggregate it and send it to BS. The main features of such
• Each node has a unique ID and ﬁxed position .
• Only CH node performs additional computation on the
data to conserve energy of the network
• The sending node can adjust the transmit power to save
energy depending on the distance to the receiver.
0 10 20 30 40 50 60 70 80 90 100
Fig. 2. Sensor Network Model
FIRST ORDER RADIO MODEL PARAMETERS
Message size 4000
In this paper we use ﬁrst order radio model, its parameters
are given in table. (1). The energy consumption of the CH
) and cluster member node (E
) can be calculated
by following equations.
(n/k − 1) (1)
is the distance between CH and BS, d
the distance between CH node and member node, E
energy consumption of transceiver ampliﬁcation circuit, E
is data aggregation energy, E
is the transmission energy of
the transceiver circuit and l is the length of packet.
is the energy consumption by CH in receiving data
from member nodes. E
is the energy consumption by CH
in aggregating the data. E
is the net energy consumption
of the transceiver ampliﬁcation circuit. E
is the net energy
consumption in transmitting the data.
In this section we explain our proposed protocol known
as LPCH. In LPCH, we remove the deﬁciencies of LEACH
protocol. We use the network model given in section 4.1.
According to the model, network ﬁeld is divided into two
physical regions. So in our proposed protocol we change the
criteria of CH selection, to select optimum number of clusters
in each region. Cluster forms are of lower size. So that energy
of the network is conserved. Operation of LPCH is divided
into rounds. In ﬁrst round, in each region CHs select according
to LEACH algorithm with little modiﬁcation. Because in ﬁrst
round all the nodes are eligible to be CH. Each node choose
a random number between 0 and 1. Then, this number is
compared with the threshold valve. Threshold value is set as:
T (n) =
1 − p ∗ (rmod(1/p))
For any node, if the number is less than or equal to threshold
value, the node become CH in ﬁrst round. From second round
to last round, CHs select according to previous CH nodes.
A node, whose y-coordinate is less than CH’s y-coordinate,
also its y-coordinate is closest to CH’s y-coordinate select
as CH for current round. When the down most node select
as CH then in next round top most node become CH, this
process continues throughout the network lifetime. In LPCH
we improve algorithm of CH selection, for efﬁciently energy
consumption of the network. However cluster formation is
remain same as discuss in LEACH [?].
1) Algorithm of LPCH: 1- Each node has ﬁxed location
and unique ID is assigned by algorithm given below.
If(it is in region1)
For a node in the network
Put node ID in
Put node ID in
Fig. 3. Algorithm of putting ID to nodes in each region
2- In ﬁrst round CHs select according to LEACH algorithm
in each region.
3- From second round CHs select according to previous
CH nodes. A node select as CH if its y-coordinate is less
than y-coordinate of CH and its Y-coordinate is closest to Y-
coordinate of CH as shown in Fig.4.
4- If more than one node Y-coordinates are closed to CH
node, then node with lowest ID become CH.
5- When down most node become CH in current round,
then in next round the top most node become CH.
6- If distance of a node from BS is less than its distance
from CH, it sends data directly to BS.
In ﬁrst round of LPCH; CHs are selected by LEACH
algorithm in individual region, and that number of CHs remain
same for all rounds. According to network model equal
Expected Cluster Boundries
Expected Next Cluster Boundries
Fig. 4. Topology of the ﬁeld for n
number of nodes are randomly deployed in each region. So
in LPCH there is guarantee of selecting optimum number of
CHs in the network. However, there is no guarantee of equal
number of CHs in both regions. We can increase efﬁciency
of the network by selecting equal and optimum number of
CHs in each region and that number of CHs could be remain
same for all rounds. We explain a new routing protocol known
as UDLPCH. In ﬁrst round of UDLPCH a node with ID (i)
become CH if (mod(i, q) == 0). Where q = round(n/k), n
is total number of nodes and k is optimal number of CHs.
For example: if n = 100 and k = 6 in overall network,
then q = 16. According to network model ﬁrst ﬁfty nodes are
randomly deployed in ﬁrst region and the remaining ﬁfty nodes
are deployed randomly in the second region. Then according
to UDLPCH, nodes with ID 16, 32 and 48 select as CHs in
ﬁrst region and nodes with ID 64, 80 and 96 select as CHs
in the second region. Hence, in ﬁrst round equal number of
CHs are selected in each region. From second round to last
round, CHS select according to LPCH algorithm as discussed
in the above section. Hence, throughout the network lifetime
optimum number of CHs remain same in each round.
1) Operation of UDLPCH : 1- In ﬁrst round equal number
of CHs select in each region.
2- Network coverage of UDLPCH is increased by selecting
equal number of CHs in each region. Also equal size of
clusters are formed.
3- Distance between CH and cluster member decrease,
because of optimum number of CHs selection in each region.
Therefore energy consumption of cluster member are reduce.
V. SIMULATIONS AND RESULTS
We proposed two types of clustering based protocols: LPCH
and UDLPCH. For simulation of LPCH and UDLPCH we use
network model given in section 4.1 with N=100 nodes and
100m x 100m ﬁeld. Our goal in conducting the simulation
• Compare the performance of LPCH, UDLPCH and
LEACH on the basis of stability period and throughput .
• Study the effect making number of CHs constant.
Following are two subdivisions of this section. In ﬁrst part
LPCH is compared with LEACH and in second part we explain
how UDLPCH performs better than LPCH and LEACH.
1- We run the simulations ﬁve times, average results of
simulations are shown in ﬁgures given below. Fig.6 shows
number of dead nodes per round. It is obvious from the ﬁgure
that, stability period of LPCH is 10% greater than LEACH.
Because, LEACH does not guarantee of selecting optimum
number of CHs in each round. Where in LPCH, ﬁeld is divided
in to two regions and the number of CHs select in ﬁrst round
of each region are maintained till the end of the network.
Fig.7 shows alive nodes per round also show that network
lifetime of LPCH is greater than LEACH. This is because in
Expected Cluster Boundries
Expected Next Cluster Boundries
Fig. 5. Operation of UDLPCH
0 500 1000 1500 2000
Number of rounds
Number of dead nodes
Fig. 6. Comparison of dead nodes in LEACH, LPCH and UDLPCH
LEACH epoch is constant even in the unstable period. If all
the nodes become CH once in ﬁrst rounds of the epoch than in
the remaining rounds nodes do not select as a CH in the same
epoch. All nodes directly send data to BS therefore, nodes
consume more energy. In LPCH there is constant number of
CHs in each round. So, there are always CHs to send data
0 500 1000 1500 2000
Number of rounds
Number of alive nodes
Fig. 7. Comparison of alive nodes in LEACH, LPCH and UDLPCH
of cluster members to BS therefore, energy of the network is
conserved. That is why network life time of LPCH is greater
Fig.8 shows that total numbers of packets sent to BS in
LPCH is 350% greater than LEACH. Because in LPCH each
cluster member decides to send its data to CH or directly to
0 500 1000 1500 2000
Number of rounds
Number of packets sent to BS
Fig. 8. Comparison of throughput in LEACH, LPCH and UDLPCH
BS. Because BS has no power constrains. In LPCH node sends
data to BS directly. If distance of a node from BS is less than
its distance from CH where, in LEACH node sends data to
BS if there is no CH in the running round.
2- As in previous section we explain that the stability period
of LPCH is greater than LEACH. However, Fig. 6 shows
that an average stability period of UDLPCH is 8% greater
than LPCH and 20% greater than LEACH. Because in LPCH,
CHs are selected by LEACH algorithm in ﬁrst round. Hence,
number of CHs select in each region may be different. The
region which has more number of CHs die ﬁrst. However,
in UDLPCH optimum number of CHs are selected in each
region, and that number of CHs remain same throughout the
Fig.6 and Fig.7 also show that the unstable period of
UDLPCH is less than LPCH. Because in both regions equal
and optimum number of CHs are selected. Therefore all nodes
consumes balance energy.
Fig.8 shows that number of packets sent to BS in UDLPCH
is 12.5% greater than LPCH and 400% greater than LEACH.
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