Energy Efficient Sleep Awake Aware (EESAA) intelligent Sensor Network routing protocol

Abstract

Wireless Sensor Networks (WSNs), with growing applications in the environment
which are not within human reach have been addressed tremendously in the recent
past. For optimized working of network many routing algorithms have been
proposed, mainly focusing energy efficiency, network lifetime, clustering
processes. Considering homogeneity of network, we proposed Energy Efficient
Sleep Awake Aware (EESAA) intelligent routing protocol for WSNs. In our
proposed technique we evaluate and enhance certain issues like network
stability, network lifetime and cluster head selection process. Utilizing the
concept of characteristical pairing among sensor nodes energy utilization is
optimized. Simulation results show that our proposed protocolnificantly
improved the

Full text

arXiv:1212.4106v1 [cs.NI] 17 Dec 2012
1
Energy Efficient Sleep Awake Aware (EESAA)
Intelligent Sensor Network Routing Protocol
T. Shah, N. Javaid, T. N. Qureshi
COMSATS Institute of Information Technology,
44000, Islamabad, Pakistan.
Abstract—Wireless Sensor Networks (WSNs), with growing
applications in the environment which are not within human
reach have been addressed tremendously in the recent past. For
optimized working of network many routing algorithms have
been proposed, mainly focusing energy efficiency, network life-
time, clustering processes. Considering homogeneity of network,
we proposed Energy Efficient Sleep Awake Aware (EESAA)
intelligent routing protocol for WSNs. In our proposed technique
we evaluate and enhance certain issues like network stability,
network lifetime and cluster head selection process. Utilizing
the concept of characteristical pairing among sensor nodes
energy utilization is optimized. Simulation results show that our
proposed protocolnificantly improved the network parameters
and can be a useful approach for WSNs.
Index Terms—Energy efficient, protocol, sleep, awakw
I. INTRODUCTION
Advancement in technologies, devices many opportunities
for efficient usage of resources in critical atmospheres. Wire-
less Sensor Networks (WSNs) brought a revolutionary change
in this context. Gathering and delivering of useful information
to the destination, became able with advent of this technology.
Applications like battlefield surveillance, smart office, traffic
monitoring and etc, can be well monitored through such
schemes.
WSN is composed of multiple unattended ultra-small,
limited-power sensor nodes deployed randomly in the area
of interest such as inaccessible ares or disaster places for
gathering of useful information. Miniature sensor nodes ca-
pable of sensing, processing useful information from, and
transmitting to destination has opened many research issues.
These battery powered sensor nodes are mounted with limited
processing and storage facilities. As WSNs are exposed to
dynamic environments, due to such configuration connectivity
loss of nodes may degrade the performance of network.
Design of protocols which should be energy efficient and
hence, enhancing the network life time is important for better
performance. Centralized algorithms are effected badly when
a critical node stops working and thus, results in a serious
protocol failure. In contrast, distributed protocols can handle
such failures more efficiently and can be a suitable solution.
Clustering structured routing protocol capable of data aggre-
gation are designed for energy efficiency of a network. Within
a cluster localized algorithms can operate without any wait
of control messages and hence, reducing the delay. Better
scalability is also achieved through these localized algorithms
when compared with centralized one’s.
In this paper. we evaluate the performance of clustering
algorithms on the basis of stability period, network life time
and throughput for WSNs. We enhance the above mentioned
parameters. Information from sensor nodes is forwarded to
cluster heads (CHs) and these CHs are responsible to transmit
this information to base station (BS) which is placed far away
from the field.
Clustering algorithms like LEACH, and DEEC [1,5] for
sensor networks have achieved reasonable goals regarding
better performance of networks. Following their thoughts
we proposed a new pairing concept based on applications
and specified distances between the sensors which will yield
significant improvements in the efficiency of network.
Rest of the paper is organized as follows: Section II
describes related work whereas, Section III describes our
protocol EESAA and section IV describes simulations. In the
end we concluded the paper.
II. RELATED WORK
In WSNs, (Homogenous, Heterogenous) energy always re-
mains a constraint. Many techniques have been proposed to
utilize energy of sensor nodes in a better way. Concept of
clustering yields significant results in optimizing energy cost
for both homogenous and heterogenous networks. In clustering
some of the nodes are selected as CHs and had to spent
more energy than rest of nodes for a specific period of time.
This high energy consumption is due to aggregation and long
range transmission of data. Many clustering algorithms e.g.,
LEACH, PEGASIS, DEEC, SEP, E-SEP [1,2,5,4,6].etc have
been proposed which discuses the efficient usage of energy in
sensor networks.
CHs in LEACH [1] protocol are selected periodically and
energy drains uniformly by role rotation. In PEGASIS [2]
energy load is distributed by forming a chain itself or being
organized by BS. For such chain formation global knowledge
about the network is essential and results in wastage of
resources. In DEEC [5] , sensor node are independently elected
as CHs based initial energy and residual energy. SEP [4] is
designed to deal with heterogenous networks which introduced
the concept of advance and normal nodes for cluster head
election.
Performance is evaluated on the basis of network stability
period, clustering process and throughput. In our EESAA,

2
keeping homogeneity in mind we tried to enhance all these
parameters. EESAA keeps the merits of distributed clustering
as well.
III. EESAA: THE PROPOSED PROTOCOL
In this section, we present a new routing protocol for
homogenous networks called EESAA. Our goal is to minimize
energy consumption in order to enhance network stability
period and network lifetime. For this purpose, we introduced
the concept of pairing. Sensor nodes of same application and
at minimum distance between them will form a pair for data
sensing and communication. In our EESAA protocol, we also
enhance CHs selection technique, by selecting CHs on basis of
remaining energy of nodes. More comprehensive description
of coupling among nodes is defined as follows.
A. Advance Coupling Network Model (ACNM)
In this section, we explain Advance Coupling Network
Model(ACNM). Initially senor nodes measure their location
through GPS (Global Positioning System). The nodes transmit
their location information, Application type and N ode I D
to the Base Station (BS). Then, this gathered information is
utilized by BS to compute mutual distance between nodes.
Nodes which are at minimum distance from each other in
their intra cluster transmission range and of same application
type are coupled in pair by BS. Then BS broadcast pairing
information to all the nodes in network. Nodes become aware
of their coupled node. During coupling process some nodes
are left out because they are not in inter cluster transmission
range of any other node.
According to the proposed scheme, The nodes switch be-
tween ”Sleep” and ”Awake” mode during a single commu-
nication interval. Initially node in a pair switch into Awake-
mode also called Active-mode if its distance from the BS is
less then its coupled node. Node in Active-mode will gather
data from surroundings and transmit this data to CHs. During
this period transceiver of the coupled node will remain off,
and switches into Sleep-mode. Sleep-mode nodes cease their
communication with CHs and only sense the network status.
In next communication interval, nodes in Active-mode switch
into Sleep-mode and Sleep-mode nodes switch into awake-
mode. In this way, we are able to minimize energy consump-
tion because nodes in Sleep-modes save their energy by not
communicating with the CHss. Nodes in Sleep-mode also save
their energy by avoiding overhearing and idle listening during
Sleep-mode. Isolated nodes remain in Active-mode for every
round till their energy resources depleted.
B. Network Settling Phase (NSP)
In NSP, optimal number of CHs are selected with the help of
distributed algorithm. Initially all nodes have same energy and
network is homogenous in terms of energy level. In LEACH
[1] protocol every node decides to become CH or not in current
round. The decision is based on desired percentage of CHs per
round which is Pd. In order to assure average number of CH
(Pd×N) for N number of nodes, Leach allows each node to
become CH after every 1/Pdrounds. Number of rounds after
which a node become CH refer to as epoch. In homogenous
network, energy of nodes after first round can not be same. If
the epoch for some high energy nodes and low energy is same,
these nodes have same probability to become CHs. There is
no proper distribution of CH responsibilities, nodes with low
energy will die quickly as compare to nodes with high energy.
In our EESAA protocol the CHs selection after first round is
based on remaining energy of each node.
Nodes in Active-mode take participation in CH election
process. In first round when all nodes have same initial energy
Eo, nodes in Active-mode will elect them self as CHs on
the basis of probability of selecting CH using distributed
algorithm. Each node chose a random number between 0 to 1
and compares it to a threshold Th, which is calculated as:
Th=(Pd
1−Pd∗((firstround)mod 1
Pd)if n∈A
0otherwise (1)
where, A is the set of nodes which are in Active-mode
in first round. If the random number selected by node is
less then threshold Th, Node will elect itself as a CH and
called as Parent-Cluster-Heads (PCHs). When node has been
selected as PCH, it broadcasts an advertisement message to
whole network. Only Active-mode nodes hear the broadcast
advertisements from different PCHs, They select their PCHs
on the basis of Received Signal Strength Indication (RSSI) of
advertisements. When an Active-mode node decides to which
cluster it wants to associate, it transmits a request to that
PCH using Carrier Sensed Multiple Access (CSMA) MAC
protocol to avoid collision. Along with request Active-mode
nodes also transmit their energy information to the PCH. The
PCH computes the remaining energy and its distance from
each node and select CH, called Child-Cluster-Head(CCH),
for the next round. CCH is selected on the basis of maximum
remaining energy of nodes. If different nodes have same
remaining energy then a node at minimum distance from PCH
is selected as CCH. When PCH selects CCH, it sets up TDMA
schedule for associated nodes for communication. PCH then
broadcast CCH information and TDMA schedule associated
nodes in its cluser. Each node in cluster transmit its data to
PCH in its TDMA slot.
C. Network Transmission Phase (NTP)
In NTP, all nodes in Active-mode, transmit their sensed
data to CH during their assigned TDMA slots. Nodes in
Sleep-mode do not take participation in NTP and thus save
their energy by turning their transceiver off. CHs aggregates
received data form each nodes and transmit to BS. Data
aggregation is a key signalling technique to compress the
amount of data. Due to data aggregation technique a noticeable
amount of energy is saved. If there are N total number of nodes
and k are the optimal number of CHs then the average number
of nodes in each cluster will be:
N
K−1(2)

3
0 10 20 30 40 50 60 70 80 90 100
0
20
40
60
80
100
pair2
pair3
pair4
pair5
pair6
pair7
pair8
pair9
pair10
pair11
pair12
pair13
pair14
pair15 pair16 pair17
pair18 pair19
pair20
pair21
pair22
pair23
pair24
pair25
pair26
pair27
pair28
pair29 pair30
pair31
pair32
pair33
pair34
pair35
pair36
pair37
pair38
pair39
pair40
pair41
Isolated
nodes
Coupled
nodes
Fig. 1. Advance Network Coupling Model
In order to transmit data, The radio of a non-CH node
dissipates ET X to run the transmitter circuitry and Eamp for
transmit amplifier to achieve acceptable SNR (Signal-to-Noise
Ratio). So, for transmission of LCbit message a non-CH node
expands:
Enon−CH =N
K−1(ET X ×LC×Eamp ×LC×d2
toCH
(3)
To receive data from non-CH node on by the radio of CH in
each cluster expands:
Erec = (ERX ×Lc)N
K−1(4)
where, ERX is energy dissipate by receiver circuitry for
receiving data. Energy dissipated by CH to aggregate data
received from its associated nodes.
EAGR = (EAD ×Lc)N
K(5)
Transmission energy ETdissipates by CH to transmit
aggregated data to the BS is:
ET=ET X ×LA×Eamp ×LA×d2
toBS (6)
where, LAis aggregated data and d2
toBS is the distance
between CH and BS. Total energy dissipated by CH a round
is:
ECH =Erec +EAGR +ET(7)
Total energy dissipate by CH is the energy dissipated in
reception of data from its associated nodes,aggregation of
received data and transmission of that data to the BS.
D. Node Mode Setup Phase (Node Mode Setup Phase)
In this phase, Every node decides whether switch to sleep
mode or active mode for the next round. Active-mode node
first check that weather it is CCH or not. If it is not CCH it
will turn its transceiver off and switch into sleep mode. If it
is elected as CCH, it will remain active for the next round.
Sleep-mode nodes switch to active if their coupled partner not
selected as CCH. Nodes are not coupled with any other node
will remain active through its lifetime.
Algorithm 1 : Node Mode Setup Phase
1: END OF ROUND
2: if ( node == coupled ) then
3: if ( node mode==active && CCH FLAG==1) then
4: node mode=active
5: else if (node mode==active&&CCH FLAG==0) then
6: node mode = sleep
7: else if (node mode==sleep&&neighbor CCH FLAG==1)
then
8: node mode=sleep
9: else if (node mode==sleep&&neighbor CCH FLAG==0)
then
10: node mode=active
11: end if
12: else if (node==coupled&&node neighbor==dead) then
13: node mode=active
14: else
15: node mode = active
16: end if
Above algorithm defines how nodes switch between sleep
and awake mode in our EESAA protocol. Node will first check
that it is coupled or not. If node is coupled then node check
its mode and if it is in Active-mode then it check its CCH
flag. If its CCH flag is ON, it will remain in Active-mode. If
node is in Active-mode and its CCH flag is not ON it will
switch into Sleep-mode. If node is in Sleep-mode, it checks
that whether its coupled partner’s CCH flag is on or not. If
node’s coupled partner’s CCH flag is on it will remain in sleep
mode. If not then node switches to active mode. If coupled
partner of a node is dead it will remain active. All that nodes
which are left out in coupling process remain active for whole
network life time.
IV. SIMULATION RESULTS
We measure the performance of our proposed protocol
EESAA by performing comparative simulations. In our sim-

4
Network
Settling
Phase
Network Transmission
Phase
Compare
RSSI,
link
quality,
Type
In CH
range
Yes
No
All nodes send their
location info to BS
BS uses central coupling algorithm to make
couple among nodes with same application and
at minimum distance
Coupled
No
Yes
All other nodes are coupled with
any one of the their neighbor
BS broadcast their status
information
NoYes
PCHs
Active mode
In CHs
range
Receive CHs
Advertisements
CCHs
Broadcast CH
advertisement
Wait and listen
medium till selection
Receive AS-Req
from nodes Send AS-Req to CH with
energy information
Receive
TDMA
slot from
PCH
Receive data
from nodes
Send sensed data
in assigned slot
Aggregate received data
from member nodes Base Station
Nodes receive their status update and
become aware of their coupled partner
Every coupled node will compare its distance to BS to
its partner distance to BS
Node will remain active if distance is less than its partner
Awake
mode
All active mode nodes
Yes
No
Some Active-
nodes are
selected as
CHs based
on probabilty
Nodes switch to
sleep-mod
CCH
Compare the residual
energy of each node and
measure distance between
nodes and itself
PCHs select the CCHs
for next round
PCHs assign TDMA slot for data
transmission and broad TDMA schedule
and CCH information
Start
End
Fig. 2. Flow chart of EESAA
ulations we generate a sensor field of 100m×100msize. In
this field we randomly drop nǫ(100) sensor nodes with initially
energy Eo. Parameters for our simulation are given in table I.
For analyzing and comparing the performance of EESAA
protocol with LEACH, SEP and DEEC protocols we consider
the following metrics as given in [1,3,4].
1) Stability period: It is duration of network operation from
start till first node dies.
2) Network lifetime: Network lifetime is duration from start
till last node is alive.
3) Instability period: It is duration of network operation
from first node dies till the least node dies.
4) Number of Cluster-heads:It indicates the number of
clusters generated per round.
5) Packet to BS: It is rate of successful data delivery to BS
from CHs.
We analyze network lifetime of LEACH, SEP, DEEC and
our EESAA protocols. We examine the way the number of
alive nodes varies as network evolves. In fig 3 it is depicted
that EESAA has a prolong stability period as compare to the
other protocols. In EESAA first node dies around 1800 round.
Stability period of EESAA is almost 120%50%and 35%

5
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
0
50
100
number of rounds
Number of dead nodes
DEAD NODES
LEACH
DEEC
SEP
EESAA
Fig. 3. Dead Nodes for 100m×100mNetwork with 100 nodes
0 1000 2000 3000 4000 5000 6000
0
10
20
30
40 Count of Cluster Head
Number of rounds
Number of Cluster−Heads per round
LEACH
DEEC
SEP
EESAA
Fig. 4. CHs per round
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
0
1
2
3
4x 104
Number of rounds
Number of packets
PACKETS TO BS
LEACH
DEEC
SEP
EESAA
Fig. 5. Packet to BS Nodes for 100m×100mNetwork with 100 nodes
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
0
50
100
Number of rounds
Number of alive nodes
ALLIVE NODES
LEACH
DEEC
SEP
EESAA
Fig. 6. Alive Nodes for 100m×100mNetwork with 100 nodes
TABLE I
SIMULATION PARAME TERS
Parameter value
Network size 100m * 100m
Initial Energy .5 J
Pd.1 J
Data Aggregation Energy cost 50pj/bit j
Number of nodes 100
Packet size 4000 bit
Transmitter Electronics (EelectTx) 50 nJ/bit
Receiver Electronics (EelecRx) 50 nJ/bit
Transmit amplifier (Eamp) 100 pJ/bit/m2
greater than LEACH, SEP and DEEC respectively. From fig
3 it is also depicted that EESAA has 100%102%and 50%
maximum network life time as compared to LEACH, SEP
and DEEC. It is because of sleep-awake property of nodes
and effective cluster-head selection’s algorithm.
From Fig.4 we notice that the first node dies around 1700
and last node dies after 4000 rounds. This shows that in
EESAA instable region starts very later as compare to other
protocols. Figure 5 also shows that there is sudden increase in
number of dead nodes in SEP and LEACH protocols whilst in
EESAA nodes dies at a constant rate. This observation depicts
that in EESAA energy dissipation is properly distributed
among all the nodes in the network which in result increases
network lifetime.
In Fig.5 we analyze the number of CHs selected in every
round for all routing protocols. As shown in Fig.6 SEP, DEEC,
LEACH has more uncertainties in CHs selection. Random
number of CHs are selected in every round but ESSA has
some patterns and controlled CHs selection. EESAA efficient
CHs selection algorithm helps it in better and constant data
rate transmission to BS. Although EESAA has sleep-awake
policy for nodes and less number of data is transmitted to
BS however, ESSAA successful data delivery to BS is much
better than SEP and LEACH although SEP and LEACH is
transmitting data continuously. Other main reason of higher
data rate achievement is longer network life time of EESAA.
Successful data delivery is shown in Fig 6.

6
V. CONCLUSION
In this paper, we presented a more optimized routing scheme
for WSNs. Main focus was to enhance cluster-head selection
process. In EESAA, CHs ale selected on the basis of remaining
energy. In EESAA nodes also switches between sleep and
active modes in order to minimize energy consumption. In
our proposed strategy, stability period of network, and life
time has been optimized. Simulation results show that their
is significant improvement in all these parameters when com-
pared with some of the existing routing protocols e.g., SEP,
LEACH and DEEC.
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