Wireless Sensor Network, 2009, 1, 1-60
Published Online April 2009 in SciRes (http://www.SciRP.org/journal/wsn/).
Copyright © 2009 SciRes. Wireless Sensor Network, 2009, 1, 1-60
Extending the Network Lifetime Using Optimized Energy
Efficient Cross Layer Module (OEEXLM) in Wireless
Sensor Networks
T. V. Padmavathy
Department of Electronics and Communication Engineering, SSN College of Engineering, Chennai, India
Email: Padmavathytv@ssn.edu.in
Received February 11, 2009; revised March 10, 2009; accepted March 13, 2009
In wireless sensor network, the primary design is to save the energy consumption as much as possible while
achieving the given task. Most of recent researches works have only focused on the individual layer issues
and ignore the importance of inter working between different layers in a sensor network. In this paper, we
use a cross-layer approach to propose an energy-efficient and extending the life time of the sensor network.
This protocol which uses routing in the network layer, and the data scheduling in MAC layer. The main ob-
jective of this paper is to provide a possible and flexible approach to solve the conflicts between the require-
ments of large scale, long life-time, and multi-purpose wireless sensor networks. This OEEXLM module
gives better performance compared to all other existing protocols. The performance of OEEXLM module
compared with S-MAC and directed diffusion protocol.
Keywords: Routing, Medium Access Control, Life Time of the Network, Energy Efficiency, OEEXLM
Module, Wireless Sensor Networks
1. Introduction
Wireless sensor network consists of large number of
sensor nodes are randomly distributed in a region. Each
node has a limited energy supply and generates informa-
tion when ever event occurs that needs to be communi-
cated to a sink node. The focus of this paper is on the
computation of optimal energy usage for data transfer
and link schedule that maximize the network lifetime.
However most wireless sensor network energy consump-
tion operations involve sensing, computing, and communi-
cating [1]. Generally, communication between nodes con-
sumes more energy than local processing or collecting data
operation. The geographical nature of the deployment
space of nodes makes quasi impossible the replacement or
the recharging operations of batteries. The challenge is to
economize energy inside every node in order to maintain
as long as possible the network functionality.
2. Related Works
Many research works are developed for energy effi-
ciency at each layer of protocol stack by proposing new
algorithms and protocols. In particular, MAC layer was
of great interest for many researchers because it is con-
sidered as an important source of energy wastage such
as overhearing, collision, control packet overheads and
idle listening [2].
In order to decrease or if possible to eliminate these
various sources of energy wastage, several protocols has
been proposed during last years and which are divided
into two main classes: Schedule based protocol TDMA
and Contention based protocol.
In TDMA protocols [3] are employed to avoid colli-
sions by associating a slot time for each sensor node in a
given cluster. This protocols more complex in the WSN
where the nodes in general have a same priority and very
limited resources. The Contention-based protocols are
known as CSMA-based are usually used in the multi-
hop wireless networking. But this protocol generates
collisions due to these useless retransmissions which
cause energy consumption wastage and time consuming
in data transmission.
Some of the power control problems are discussed in
[4,5]. Approaches at MAC layer are Dermikol et al. [4]
infers that some pros and cons of the some of the exist-
ing protocol. One of the first attempts at MAC protocol
for WSN is PAMAS, which reserves battery power in-
Copyright © 2009 SciRes. Wireless Sensor Network, 2009, 1, 1-60
telligently powering off users that are not actively
transmitting or receiving packets. This protocol de-
creased the energy consumption of the network but
maximum latency occurs. Raghavendra et al. [5] the
Power Aware Medium Access protocol and Signaling
(PAMAS) is a CSMA based protocol in which the nodes
that are not actively transmitting or receiving should
power themselves off. The protocol requires the nodes to
have two separate channels (control and data), which
will require two radios at each node increasing the cost,
size and complexity of the sensor design.
Existing MAC protocol [6,7] turn off the transceiver
when there is no communication between the nodes also
the power savings in these papers results reducing the
idle listening power but also decreasing the collisions. In
these papers they proposed adaptive listening incurs
overhearing. Sleep and listen periods are predefined and
constant, which decreases the efficiency of the algorithm
under variable traffic load.
A new generation of MAC protocols that is Cross-
layer MAC protocols using several layers in order to
optimize energy consumption has been emerged. These
layers can be divided into interaction mode or unification
mode. In the interaction mode, the MAC protocol is built
by exploiting the data generated by other adjacent layers.
Approaches at network layer in WSNs are mostly
used to implement the routing of the incoming data, as
quoted in [8]. It is known that generally in multihop
networks the source nodes cannot reach the sink directly.
Therefore, intermediate sensor nodes have to relay their
packets. Generally, the implementation of routing tables
offers the solution. These routing tables contain lists of
node options for any given packet destination Definition
of the routing tables is the task of the routing algorithm
along with the help of the routing protocol for their con-
struction and maintenance.
MAC-CROSS Protocol [9] is an example of Cross-
layer approach which allows the interaction between
MAC and information of the network layers by making
only the communicating nodes in listening mode and by
putting other nodes into sleep mode. In order to avoid
collisions, MAC-CROSS uses the control messages
RTS/CTS/ACK. On the other hand, a Cross-layer design
mode by unification requires the development of only
one layer including at the same time functionalities of
considered layers.
In this paper, a unified cross layer module XLM [10]
is developed which achieves efficient and reliable event
communication between the nodes with minimum en-
ergy expenditure. But in this protocol the end-to-end
delay increases for low value duty cycle. When the duty
cycle is low =0.1, 14% of the transmitted packets are
dropped due to retransmission timeout. Because sender
nodes cannot find any neighbors that satisfy the constraints.
Weiyan Ge et al. [11] addressed the rate optimization
for multicast communications at the media access con-
trol (MAC) layer, and explore transport layer erasure
coding to enhance multicast reliability in wireless sensor
networks. In this approach they are not addressed the
energy consumption and end-to-end delay.
3. Proposed OEEXLM Module
The proposed cross layer approach replaces the entire
traditional layer protocol architecture that has been so
far used in WSNs. In this protocol we integrate the me-
dium access control and routing to improve the perform-
ance of the network. The communication in OEEXLM
module is based on initiative concept. This module al-
lows the each node to decide whether it can participate
in communication or not. Consequently, this protocol
uses adaptive receiving, stagger scheduling algorithm
and logical link decision algorithm.
A node starts a transmission by transmitting to its
neighborhood an RTS packet to indicate that it has a
packet to send. Upon receiving an RTS packet, each
neighborhood node i decide to participate to communi-
cation or not, that decision can be determined by an ini-
tiative “I” defined as follows:
I= 1
rev rev
β= γ=γ
The initiative is set to 1 if all four conditions are true
or satisfied. Out of four conditions, the first two condi-
tions related to MAC layer and next two conditions re-
lated to network layer. The first condition checks event
β occurs or not. If
= 1 then the remaining three condi-
tions checked by the node, otherwise the nodes are go to
sleep mode.
Because of this, idle listening and overhearing are
avoided. The second condition is adaptive receiving
scheme, the receiver node wait for TA seconds if the
node does not receive any packets from upper layer it
goes to sleep state. The third condition is the node will
check the buffer size γth if the size is less than threshold
it will choose the alternate path to reach the destination.
Fourth condition is that source node from upper layer
checks the lower layer receiver node energy if it is
greater than threshold Ethd
rev then it will transmit packet
otherwise it will choose the alternate path.
Using this initiative concept, OEEXLM module over-
comes collision, overhearing, idle listening and improve
the throughput, link reliability and extend the life time
of the network.
3.1. Basic Terms Used in OEEXLM
The following assumption can be considered for OE-
EXLM protocol to study the performance. The network
topology used in this protocol is grid architecture. Data
flows from n layer to n-1 layer until the data packet
reached the destination. For simulation MICA2 mote
specification is considered. In this protocol the value of
duty cycle is denoted by
and is defined as ratio of the
time a node is active. The duty cycle is varied with re-
Copyright © 2009 SciRes. Wireless Sensor Network, 2009, 1, 1-60
spect to data transmission. The sleep time for each node
T sec. The listen period of each node is less than or
equal to transmission period of upper layer. Transmis-
sion period each layer is 50ms. With in 50ms if lower
layer node does not receive any data from upper layer it
will wait for TA sec and go to sleep.
3.2. Initiation of Transmission
When the event occurs that is
=1 layer n node has a
data packet to transmit, it sends RTS signal to the
lower layer, the lower layer sends the CTS signal to the
upper layer with response the CTS signal the layer n
sends the data to the layer (n-1) for 50ms.During the
receiving period, if a node senses that the channel is
idle and its neighbours are not communicating for a
time TA, it will go to sleep until its subsequent sending
periods. After receiving the packet from n layer, the n-
1 layer route the packets to the destination, each source
node determines a path to the destination by selecting a
lower layer node under its coverage randomly. Thus
messages flow in the correct direction, but do not use
the same path every time. Thus this data exchange
scheme provides both collision avoidance and reliable
4. Mechanism of OEEXLM
Figure 1 explains the mechanism of OEEXLM module. In
this module we integrate the MAC and network layer. In
MAC layer we proposed Power Efficient MAC protocol
which is used to overcome idle listening, collisions, Hid-
den terminal problem, and also to provide a low latency
compared to other existing MAC protocols. The PE-MAC
uses the three algorithms to achieve the energy efficiency.
4.1. Clock Synchronization Algorithm
In clock synchronization algorithm layer n comprises the
source nodes. Initially the nodes in layer n are in sending
mode for 50ms while those in the layer (n-1) are in re-
ceiving mode. The remaining nodes are in sleep state.
Assume that the source nodes generate packets (layer-n).
As the next layer nodes are in the receiving mode, the
source nodes can transmit the packets directly without
checking the status of the lower layer nodes. The pack-
ets are stored in the buffer space of the lower layer
nodes. Once the receiving period of layer (n-1) nodes
ends, the sending period for layer (n-1) starts. The layer
(n-2) nodes shift from sleep mode to receive mode. The
remaining nodes enter the sleep mode.
4.2. Logical Link Decision Algorithm
The LLD algorithm is implemented in this protocol to
ensure that two source nodes do not transmit the packets
to the same receiver at the same time. This algorithm is
implemented initially when each source node determines
a link to the sink. When all the source nodes determine
their links, the links are compared to ensure that there is
no overlap in the existing links. If there is an overlap,
the LLD algorithm uses a logical link decision to get the
new link to the sink.
4.3. Adaptive Receiving
In Adaptive Receiving algorithm, layer n sends RTS
packet to the lower layer n-1, the lower layer sends the
CTS signal to the upper layer n. With response the CTS
signal from layer n-1, the layer n sends the data to the
layer n-1 for 50ms.Adaptive receiving scheme employs
a time interval TA to handle traffic varies.
During the receiving period, if a node in the n-1 layer
senses that the channel is idle and data from n layer are
not communicating for a time TA, it will go to sleep.
Suppose with in 50ms if the layer n-1 senses any data
from the upper layer n it wakes up and receive the data.
This adaptive receiving scheme reduces the packet drop
and improves the throughput of the network.
In network layer we proposed two algorithms: a con-
gestion control and alternate path algorithm. These two
algorithms are used to improve the lifetime of multihop
sensor network by avoiding the collision.
4.4. Alternate Path Algorithm
In alternate path algorithm, each has routing table. Be-
fore route the data packet each source finds a multiple
path to the sink. In this each source node initiate HELLO
message to all lower layer nodes.
The HELLO message contains source ID, type of
node whether it is sink or intermediate node and energy
level which is shown in Figure 2.
Each node in the lower layer updates it table once it
receives the HELLO message. If any node in lower layer
gets more than one HELLO message it sends the nega-
tive acknowledgement NACK signal to the correspond-
ing source node. Then that particular source node
chooses the alternate path to reach the sink.
After setting an alternate route the nodes in the rout-
ing path check its energy level of receiving node. If the
energy level less than the threshold Ethd
rev again the node
choose the alternate path by sending HELLO message
and the routing table is updated.
4.5. Congestion Control Mechanism and
The congestion in the network is due to two traffic. One
is due to generated packet that is whenever node detect
the events it will generate the data packets and that is to
be transmitted to the destination through intermediate
nodes. The rate of generated packets at the node i is de-
noted by
Copyright © 2009 SciRes. Wireless Sensor Network, 2009, 1, 1-60
Is Event occurs
Packet arrives at Layer n
Finding several paths
for each Source to
Selection of
Non-overlap shortest
path for each source
Transmit data
Tran smittin g
Deployment of Sensors
in the Application area
Sensors Activated
If (TA > R+T)
Set Transmission Time =
50m s
Send RTS packet to
the Routing node in
If Data
Oc curs
Data transmission starts
after receiving the CTS
Set Receiving Time =
Receive Data
Is Buffer size
Source node sends
"HELO" Packet to n-1
Is Overlap
occu rs
Ye s
Select the
Alternate path
Goes to
Sle ep
Ye s
Figure 1. Mechanism of OEEXLM.
Since the network is a multi hop each nodes plays
dual role that is it act as source as well as router. During
the transmission each node in lower layer receives the
data packet from the upper layer until the data packet
reached at the destination. These packets are referred as
relay packets. If the n-1 layer node receive the data
packets from layer n the rate of relay packet of node i of
n-1 layer is ,1
λ. The input rate of the buffer for the
node i is depends on the rate of relay packets ,1
λ and
the rate of generated packets
i. In OEEXLM module
the rate of input packet at node is buffer αi, can be
represented as
α=λ+λ (2)
The node is active for a fraction of duty cycle
50ms. Hence the average time taken a time to transmit
and receive data packet can be given by
txii pkt
+α⋅ (3)
rxi npkt
where pkt
t is the average time taken to successfully
transmit a packet to another node and i
e is the error
packet rate.
The proposed OEEXLM module avoids packet drops
due to congestion by not allowing upper layer nodes to
transmit data packet if there is not available buffer size
this is can be controlled by congestion control algo-
rithm. A lower layer node changes the path of transmis-
sion based on its buffer status. During transmission, the
lower layer node i allow Pi packets to be transmitted by
the upper layer nodes. Figure 3 shows the buffer queue
model of the node.
Given the condition that the lower layer node has pro-
portionally higher probability to access the medium,
Copyright © 2009 SciRes. Wireless Sensor Network, 2009, 1, 1-60
Source ID Type of Node Energy level
2 Byte 1 Byte 4 Byte
Figure 2. HELLO message packet format.
Figure 3. Buffer queue model.
even then the lower layer node may not be able to for-
ward all i
P packets. So, in the next transmission, the
lower layer node will have some packets from the previ-
ous transmission, which might cause Congestion within
few successive transmissions. Therefore, for each
transmission upper layer nodes check the routing table if
the buffer size
less than the buffer threshold thd
per layer node takes the alternate path. Maximum num-
ber of packet hold by the buffer is buff
N. The transmis-
sion only occur when
where buff l
As a result of congestion control algorithm, the OE-
EXLM module avoid the layer to layer congestion occur
in the networks. Because of this energy consumed by the
node is reduced there by improving the life time of the
The medium control access scheme uses three algo-
rithms to improve the energy efficiency and in network
layer we use two algorithms to improve the life time of
the networks. These two layers are integrated by using
initiative conditions as per Equation (1).
5. Network Topology
Figure 4 shows the data flow for the OEEXLM module.
The nodes in the network operate in three different
modes-sleeping, receiving and sending. Each node goes
to sleep periodically to save energy and then wakes up
and listens to see if any other node wants to talk to it.
During sleep, the node turns off its radio; therefore the
energy waste due to idle listening can be reduced.
The nodes with same layer-count are given the same
schedule, and the sending and receiving periods are
staggered layer by layer such that when one node is in
sending mode, its lower-layer node is in receiving mode.
After receiving a message from an upper-layer node,
each node can transmit it to the lower-layer node in the
subsequent sending period. So a packet can be transmit-
ted to sink nodes through multi-layers fleetly and the
end-to-end latency is reduced.
5.1. Performance Evaluation
The Table 1 shows the simulation setup used for simula-
5.1.1. Latency Vs Network Area (MAC)
Figure 5 infers that in S-MAC a node has to wait till its
neighbouring node as to awake to transmit the message
to it. This results there will be some amount of delay in
S-MAC protocol, which is absent in OEEXLM module.
In OEEXLM module whenever a node is in send state,
the lower layer node is in receiving state. So the source
node can transmit the message to the lower layer without
checking whether the lower layer node is listening or
sleeping mode. Hence the source node can transmit its
message fleetly to the sink through multi layers.
5.1.2. Energy Consumption Vs Network Area (MAC)
The Figure 6 infers that depicts the energy consumption
of S-MAC and OEEXLM module. The comparison is
made for a simulation setup with ten layers, ten nodes in
each layer and a four sink. The graph shows that OE-
EXLM module protocol uses less energy than S-MAC.
This is because the idle listening dominates the energy
consumption in S-MAC protocol but TA can make OE-
EXLM module go to sleeping mode earlier, and the en-
ergy consumption is reduced. The energy consumption
of OEEXLM module is 35% -83% les than existing S-
MAC protocol.
5.1.3. Latency Vs Number of Hop (MAC)
The Figure 7 shows that the latency encountered in OE-
EXLM module compared with that in S-MAC with respect
to number of hops. Obviously the latency of OEEXLM
Table 1. Simulation setup.
Parameters Value
Transmission Range 250 m
Network Area 100 x 100
Number of Sensors 100- 1500
Packet rate 5 pkt/sec
Packet size 512 bytes
Radio Bandwidth 76kbps
Transmitting Power 75mW (270J)
Receiving Power 36mW (129.6J)
Power Consumption in Sleep mode 100μ W (0.36 J)
Sending and Receiving Slot 50msec
Type of mote Mica2
Inital energy of sensor node 2KJ
Energy Threshold Ethd 0.001mJ
Copyright © 2009 SciRes. Wireless Sensor Network, 2009, 1, 1-60
Figure 4. Data flow diagram for OEEXLM module.
Figure 5. Latency vs network area.
module is lesser than that in the S-MAC because of
staggered scheduling algorithm. In S-MAC a node has to
wait till its neighbour is awake to transmit the message
to it. This problem is not occurring in OEEXLM module.
In OEEXLM module whenever a node is in send state,
the lower layer node is in receiving state. So the source
node can transmit the message to the lower layer without
checking whether the lower layer node is listening.
Hence the source node can transmit its message fleetly
to the sink through multi layers.
5.1.4. Latency Vs Number of Hops (Routing)
Figure 8 infers the delay as a function of the number of
nodes in the WSN. The delay increases with the number
of hops increasing. Our simulation shows the average
delay of the proposed protocol is better than that of the
directed diffusion. This is because in OEEXLM module,
for each transmission each node in the routing checks
the buffer condition, so that no queue of data occurs in
the buffer.
Due to alternate path algorithm the shortest delay oc-
cur compared to other schemes. As we expected, data
packets are routed through different node-with the help
of proper design of algorithm in routing. Hence, the net-
work congestion can be avoided.
5.1.5. Energy consumption Vs Number of Nodes
Figure 9 infers that energy consumption per node ver-
sus number of nodes. The value of node energy con-
sumption gives the average energy dissipated by the
node in order to transmit the packet from source to
drain. The same metric is used in [6] to determine the
energy efficiency level of WSNs. It is calculated as
e initiale resi
NodeEnergy Consumption
where N is the total number of nodes, initialei, initial
energy of nodes, resiei, is the residual energy of the
nodes, S is the number of sinks and
P is the number
of data packets received by the sink j.
Figure 6. Energy consumption vs network area.
Figure 7. Latency vs number of hops.
Layer n
Layer n-1
Layer 1
Copyright © 2009 SciRes. Wireless Sensor Network, 2009, 1, 1-60
Figure 8. Comparison of latency vs number of hops with DD.
Figure 9. Energy consumption vs number of nodes.
The simulation result infers that there is lower node
energy consumption in CRLS protocol over the other
schemes., The energy consumption of nodes in OE-
EXLM module is 34% to 84% lesser than when com-
pared with directed diffusion. This results shows that the
energy efficiency of OEEXLM module is stable and has
little impact by the increase of the network size, while
the performance of other schemes degrades with larger
network size.
5.1.6. Network Life Time
The system lifetime is defined as the number of rounds
for which 75% of the nodes are still alive. CRSL The
transmitted and received energy costs for the transmis-
sion of a k-bit data message between two nodes sepa-
rated by a distance of r meters are given by Equations (6)
and (7), respectively.
() ()
Ek,rEk Erk=+ (7)
Ek Ek= (8)
In Equation (7) )( r,kEt denotes the total energy dis-
sipated in the transmitter of the source node, while
Ek in Equation (8) represents the energy cost in-
curred in the receiver of the destination node. Parame-
ters tx
E and rx
E are per bit energy dissipation for
transmission and reception, respectively, and )( rEamp
denotes the energy required by the transmitted amplifier
to maintain an acceptable radio for transferring data re-
liably. The free-space propagation model is applied, and
the transmit amplifier )(rEamp is given by Equation (9)
amp FS
Er (9)
where e
S is the transmitted amplifier parameter. The
set of parameter given in [7,8].
e =10 pJ/b/m2.
From Figure 8, we infer that the network lifetime is
increased by using the alternate path and congestion
control algorithm. The network lifetime is given in terms
of rounds till which 75% of nodes are alive. A network
is assumed to be useless when one of the sensor’s en-
ergy is below the threshold.
5.1.7. Data Packet Delivery Ratio
Data packet delivery ratio can be calculated as the ratio
between the number of data packets that are sent by the
source and the number of data packets that are received
by the sink. It can be denoted as R
Successfully delivereddata
Data Delivery RatioRequired data
This parameter R indicates both efficient of the rout-
ing protocol and the effort required to receive data. In
the ideal scenario the ratio should be equal to 1. If the
ratio falls significantly below the ideal ratio, then it
could be an indication of some of the packet dropped
because of faults in the protocol design. However, if the
ratio is higher than the ideal ratio, then it is an indication
that the sink receives a data packet more than once. It is
not desirable because reception of duplicate packets
consumes the more energy. The relative number of du-
plicates received by the sink is also important because
based on that number the sink, can possibly take an ap-
propriate action to reduce the redundancy.
Figure 11 shows the data packet delivery ratio of DD
and OEEXLM modules. To eliminate packet loss we use
a rate of 5 packets/second. It is found that the delivery
ratio of the two protocols increase as the node density
increases. When node density is high, there are more
nodes available for data forwarding, and this increases
the delivery ratio. Directed diffusion protocol offers less
packet delivery rates, compared to OEEXLM module
because it does not adapt well its behavior to network
size increase. The OEEXLM module has maintained
constant delivery rates throughout the simulated scenar-
ios because the paths are selected based on the energy
availability and buffer size.
Copyright © 2009 SciRes. Wireless Sensor Network, 2009, 1, 1-60
Figure 10. Network lifetime.
Figure 11. Packet delivery ratio vs number of nodes.
Figure 12. Performance variations with respect to buffer size.
5.2. Performance Variations with Respect to
Buffer Size
Figure 12 shows the performance variations when the
buffer size varies from 50 bytes to 300 bytes. When the
buffer size is 50 bytes number of packets reached at the
destination is minimum because of congestion but
packet delay is minimum. When the buffer size 300
bytes the number of packets dropped is minimum due to
large buffer and the average delay per packet increases
due to the increased queuing delay.
5.2.1. Packet Loss with Respect Buffer Size
Figure 13 infers that packet loss get reduced due to in-
creasing buffer size. The number of packets dropped due
to buffer overflow in the case of the OEEXLM module
almost zero. This is because each time after receiving
the packets from upper layer the buffer size is calculated
and updated in the routing table. Depending on updated
value the routing path algorithm send the HELLO mes-
sage to the other nodes in the routing.
5.2.2. Packet Delay with Buffer Size
Figure 14 shows Packet delay Vs buffer size. The graph
infers that as the buffer size increases the average delay
per packet increases due to the increased queuing delay.
Figure 13. Packet loss vs buffer size.
Figure 14. Packet delay vs buffer size.
Copyright © 2009 SciRes. Wireless Sensor Network, 2009, 1, 1-60
When the buffer size is 120 bytes, packet delay is only 4
second from source to destination. When the buffer size
is 300 bytes length the delay is 12 seconds because of
queuing delay. From this graph, we find that as the
buffer size increases the packet delay also increases. But
throughput is maximum because the packet drop is
minimum by compromising the delay.
6. Conclusions and Future Work
In this paper we presented the Cross-Layer Design to
improve the performance of the wireless sensor net-
works. This protocol design is used to give the direct
interactions between the Network layer and the MAC
layer. The traditional Network layer and MAC layer
have been removed, thus simplifying the protocol stack.
Simulation results that our proposed scheme has higher
node energy efficiency, lower average delay and control
overhead than the directed diffusion protocol and S-
MAC protocol. The energy consumption of nodes in
OEEXLM module is 34% to 84% lesser than when
compared with directed diffusion. Further the network
life time is 78% improved compared to DD protocol. In
future we are going to extend the OEEXML design to
Physical layer.
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