Content uploaded by Khaled Elleithy
Author content
All content in this area was uploaded by Khaled Elleithy on Jan 12, 2014
Content may be subject to copyright.
Mobility-Aware Hybrid Medium Access Control Protocol for Wireless Sensor Network (WSN)
Abdul Razaque, Member IEEE, Khaled .M. Elleithy, Senior member IEEE
Computer Science and Engineering Department, University of Bridgeport, Bridgeport, CT 06604
Abstract— Efficient MAC protocol has been paramount
importance for improving the performance of WSN. In this
paper, Boarder Node Medium Access Control (BN-MAC)
mobility aware hybrid protocol is introduced for WSN. BN-
MAC controls overhearing, idle listening and congestion
problem to save energy. BN-MAC mechanism is based on novel
semi synchronous low duty cycle that takes less time for
accessing channel and faster delivery of data. The objective of
introducing BN-MAC protocol is to support four application
areas: monitoring and behavioral areas, controlling natural
disasters, tracking and handling home automation devices and
human-centric application areas. These application areas need
contention free mobility support features with high delivery of
data. BN-MAC also provides mobility support for these
applications.
Evaluation of BN-MAC is conducted using network simulator-2
(ns2) then compared with known low power listening (LPL) and
X-MAC low duty cycles MAC protocols. Additionally, we have
also compared BN-MAC with MAC hybrid protocols: Zebra
medium access control) (Z-MAC), advertisement-based MAC
(A-MAC), Speck-MAC, Adaptive Duty Cycle SMAC (ADC-
SMAC), low power real time medium access control (LPR-
MAC) protocol. On basis of initial Simulation results, we
demonstrates that BN-MAC protocol saves extra 18% to 45%
energy resources as compared with other MAC protocols.
General terms: Design; Experimentation; Performance;
Algorithms.
Keywords: Hybrid MAC protocols; BN-MAC protocol; mobility;
low duty cycle MAC protocols; Wireless sensor network (WSN).
1. INTRODUCTION
Wireless Sensor network is one of dominating research areas
in recent years. WSN consists of a large number of sensor
nodes with limited power, which monitor the events in order
to collect the data of interest and return back to specific
locations (e.g. Base stations, disaster control centers and
headquarters). WSN has set its impact in several applications
such as environmental monitoring, industrial sector, battlefield
surveillance and consumer applications [1]. WSN has not only
improved the standard of living but it faces many challenging
issues such as insufficient coverage, scalability, lack of
robustness, uniformity, congestion, mobility and high energy
consumption [2]. Furthermore, limited battery life and severe
operating conditions causes the node failure [3] that waste
energy in WSN.
MAC protocol plays important role in WSN that specify
how nodes share the channel for communication to improve
the WSN. There are different categories of MAC protocols
introduced such as scheduled based, contention based,
mobility aware, hybrid MAC, cross layer and real time [11] &
[21], but each MAC protocol is designed for specific type of
application [12]. Most of widely used MAC protocols are
based on contention, where access of the same communication
channel by multiple sensors cause collision [19].A collision
reduces the channel bandwidth and increases energy
consumption. In order to conserve energy, scheduled based
MAC protocols were introduced to reduce idle listening by
scheduling at regular sleep intervals [14]. However, scheduled
based MAC protocols are not accepted as a general standard
because they are application dependent. The scheduled based
MAC protocols face the inconsistency at the physical layer
and the sensor hardware. The topological change is another
issue caused by insertion and deletion of sensor nodes [15].
Hybrid MAC protocols were introduced by combining the
characteristics of CDMA and CSMA, which are energy
efficient and flexible to control mobility. From other side,
hybrid MAC protocols experience several issues. They use
long preambles that cause high energy consumption and
transmission power in Z-MAC, A-MAC and ADC-MAC
hybrid protocols [5], [18] & [22]. Speck-MAC hybrid protocol
also faces latency issues [4], [17] & [20].
Hybrid MAC protocols are not capable to control the
mobility. As result, they experiences scalability issues. Low
duty cycle MAC protocols face the severe problem due to long
preamble messages and overhead of embedded destination
address in each preamble before sending data packets. These
are some of the major issues, which need to be addressed
when designing highly robust hybrid MAC protocol. To
address these challenges, BN-MAC is introduced to support
the several applications especially disaster, surveillance,
diagnosing and monitoring. In this paper, we introduce an
initial deployment of BN-MAC protocol over WSNs.
This contribution reduces energy consumption by
controlling idle listening, congestion and overhearing
problem. It also provides faster communications and
scalability. The remaining of this paper is organized as
follows. In Section 2, a general overview for the design of
BN-MAC protocols including initial results are demonstrated
and section 3 offers conclude the paper.
2. DESIGN OVERVIEW OF BN-MAC PROTOCOL
The goal of introducing new MAC protocol is to support
multiple applications. The MAC design in WSN is ant
involved process because WSN is based on entirely different
mechanism from traditional wireless network. WSN has its
own limitations due to storage, computational power and
energy resources. Therefore, MAC should be energy efficient
and scalable. One of the key factors for introducing the new
MAC protocol is to reduce energy consumption, while
maintaining a high degree of scalability and collision
avoidance. BN-MAC protocol reduces energy consumption,
reduces collisions, minimizes idle listening, reduces
overhearing, and shortens latency while guarantying reliability
of data.
We have specially designed the WSN for BN-MAC
protocol. WSN is divided into different regions. Each region
consists of its own border node. Therefore, the messages
forwarding processes are based on intra and inter
communications. Intra communication process is used within
regions whereas inter communication is used for both region
and out of region.
2.1. BN-MAC Design
BN-MAC improves the existing X-MAC, LPL, Z-MAC,
A-MAC, Speck-MAC, ADC-SMAC, and LPRT-MAC [6] by
adding new features. The BN-MAC mechanism supports
hybrid topology that combines the features of TDMA and
CSMA. BN-MAC supports single hop communication. The
features of TDMA are used to improve contention while
CSMA works as a baseline with support of semi synchronous
technique. BN-MAC follows the concept of owner slot as
introduced in [10]. The node has complete access to its owner
slot which is similar to TDMA based approach. There is bi-
directional traffic inside each region of WSN that promotes
smooth data exchange and efficient use of the bandwidth.
Additionally, BN-MAC allocates dynamic contention free slot
exchange that improves the network scalability even under
heavy load of traffic.
BN-MAC consists of following phases: One-hop neighbor
node search, intra semi synchronous transmission, inter
synchronous transmission and election of boarder node. These
phases are operated once during the setup process and until the
network topology is physically changed. The advantages
behind this approach is to balance the initial costs for running
these operations while achieving a better throughput and
efficient energy consumption during intra and inter
transmission.
2.1.1. Finding the list of one hop-neighbors
When a node intends to start communication with its neighbor
node after accessing the channel, it sends anycast message to
its one-hop neighbor nodes to get the detail of neighing nodes.
This process helps reducing the overhead. It also ensures that
all neighboring nodes are able to talk with each other even if
they possess different schedules of sleeping and
communication. The neighbor discovery process consists of
short message. In our case, each node sends short message
using anycast randomly after two seconds for 15 seconds. The
reason of sending messages after two seconds for 15 seconds
is to get maximum throughput because we have checked the
option of packet sending interval from 1 second to 7 seconds.
The time interval of 2 seconds gives optimized throughput.
Additionally, we have set packet sending time 15 seconds that
helps to finish the packet sending process successfully. If we
set time less than 15 or higher than 15 seconds then node
energy is wasted. In case of less than 15 seconds, node is
unable to complete packet sending cycle whereas the time
more than 15 seconds, brings the node in idle situation
because finishing the packet sending task, node waits on
channel until reaches the level of set time. We show the
performance of BN-MAC at different time intervals and
packet sending durations. In Figure 1, we check the
throughput performance of BN-MAC at different time
interval. In Figure 2, we also examine that BN-MAC
consumes less energy at 15 seconds packet sending duration.
1
40 80 120 160 200
0
TIME INTERVAL (SECONDS)
THROUGHPUT(Kb/Sec)
02 3 4 5 6 7
BN-MAC
MAX
THROUGHPUT
Figure 1: Throughput at different time intervals
5
5 10 15 20 25
0
PACKET SENDING DURATION (SECONDS)
ENERGY CONSUMPTION (JOULES)
010 15 20 25 30 35
BN-MAC
MINIMUM ENERGY
CONSUMPTION
MAXIMUM ENERGY
CONSUMPTION
Figure 2: Packet sending duration versus energy consumption
The node discovery process in BN-MAC consists of 1-hop
neighbor node but nodes are to get two-hop neighbor
information. The obtained two hop information is used for slot
allocation. The slot allocation enables the node to handle the
mobility because node keeps the information when two-hop
node is even moving. BN-MAC is scalable because one-hop
topological change is easy to handle because each node knows
schedule of one hop neighbor node. BN-MAC uses promising
time scheduler because assigned slot is not exceeding more
than one-hop neighborhood. BN-MAC also performs localized
time slot allocation without changing time slots of already
existing nodes. This feature of re-use slot allocation improves
throughput and reduces the latency of nodes.
2.1.2. Intra semi synchronized transmission schedule
This phase is based on semi synchronized low duty cycle.
Intra semi synchronized process starts with channel sampling
(Ch-S). During the channel sampling process, the receiver
wakes up for short period of time to sample the medium and
the time channel sampling is done called as. Check period
(CP). During the intra transmission schedule, each node sends
a short permeable message asynchronously before sending the
data. This short preamble message gives the signal to one-hop
neighbor node to be ready for sharing the next schedule and
sending the data packets. After receiving short preamble, each
node is scheduled with its respective neighbor. This
scheduling process is performed with synchronization because
each node must know next sleep and wake up time of its
neighbor in order to set its clock accordingly. These both
features reduces the overhead because node does not take
longer time to establish the schedule for sending data packets
and building the routes. As result, node performs its task
quicker then goes to low duty. Low duty cycle means node
spends enough time in sleep state. The advantage of using
lower duty cycle is to keep the receiver and the sender as
decoupled.
A decoupled idea allows each sender and receiver node to
perform the tasks independently, while enabling network
variations between sender and receiver. It also allows both
sender and receiver remain completely autonomous. Short
preamble enabled MAC protocols have edge over long
permeable enabled MAC protocols in low powered duty cycle
architecture [7].
The existing lower power listening (LPL) technique uses
long permeable that causes the latency and overhearing
problem because node takes longer time for sending preamble
that consumes excess energy. As result, increased the latency
at each hop of network. Additionally non-targeted receivers
are also affected due to overhearing because each node
pretends to be targeted receiver.
X-MAC introduces short permeable message to reduce the
latency but it suffers due to insertion of destination address in
each short permeable message. It also induces all the nodes to
check the permeable whether they are targeted nodes or not,
which causes excess of energy consumption and makes longer
wake-up process. X-MAC is purely based on asynchronous
mechanism and it does not maintain the schedule of neighbors
that is hard for each node to communicate properly, whereas
BN-MAC deploys both features: synchronous for getting the
scheduled information of neighbors and asynchronous for
sending short permeable messages for accessing the channel
and sending the data.
BN-MAC has another good feature to avoid the packet
loss. If multiple nodes try to select same slot, BN-MAC uses
sampling and randomization that provides equal chance to
each node to access the channel. Another advantage of BN-
MAC is to use 256 congestion window slots whereas the other
MAC protocols use 1 to 32 contention window for randomized
listening before sending preamble messages. The advantage of
using 256 slots is to reduce congestion and latency and obtains
better throughput. We have used different congestion window
slots using 30% active sensor node contenders for each
window slots in WSN. On basis of experiments, we have
evaluated that BN-MAC produces better throughput at 256
slots size shown in Figure 3. Similarly, we have checked the
performance of hybrid MAC protocols: Y-MAC [23], B-MAC
and Z-MAC on their existing window size slots and compared
with BN-MAC. On basis of simulation results, BN-MAC
delivers 99.8% successful delivery of packets but other MAC
protocols achieve 46% to 72.7% successful delivery of packets
given in given in Figure 4. Hence, the 256 window slot size
makes big difference in throughput.
20
16 32 64 128 256
0
THROUGHPUT(Kb/Sec)
CONGESTION WINDOWS SLOTS
040 60 80 100 120 140
BN-MAC
Figure 3: Throughput at different congestion window slots
5
20 40 60 80 100
0
EVENT MONITORING TIME (MINUTES)
SUCCESSFUL DELIVERY OF PACKETS %
010 15 20 25 30 35
BN-MAC WITH 256 SLOTS
Z-MAC WITH 32 SLOTS
Y-MAC WITH 10 SLOTS
B-MAC WITH 32 SLOTS
Figure 4: Successful delivery of packets versus event monitoring time
We here demonstrate the process of long permeable (LPL),
short permeable (X-MAC) and BN-MAC in Figure 5. Longer
preamble takes longer time to reach the node that consumes
excess energy. Moreover, X-MAC uses short preamble with
target-address for accessing the channel to communicate with
another node but it experiences problems because all of the
nodes on the way will remain awake until short preambles are
received by the targeted node. The nodes of the network
experience the problem and consume excess energy. In case of
BN-MAC, There is more sleep time before wake up because
BN-MAC is based on one-hop neighbor mechanism. Hence
each node has already information about the schedule of
neighbor node; it wakes up only in the scheduled time.
Furthermore, we have already discussed that BN-MAC has
automatic packet buffering process, which also reduces the
wake up time and increases the lifetime of the network.
Energy consumed in short preamble sampling consists of
energy consumed for channel sampling and energy spent for
sending and receiving synchronized fames (SF).Let us assume
that the consumed energy for process of channel sampling is
ECsampling. Thus average energy spent for channel sampling
(AEsampling ) can be derived as follows:
LONG PREAMBLE
TARGET ADDRESS
IN HEADER
DATA
TRANSMIT
TX (LPL)
RX (LPL)
TIME
EXTENDED WAIT TIME
RX WAKE UP TIME
DATA
RECEIVE TIME
SP SP SP
BP
LISTEN TIME FOR BUFFER PACKETS
SHORT PREAMBLE WITH
TARGET ADDRESS
RE-
ACK DATA
TRANSMIT
TX (X-MAC)
RX WAKE UP
SE-
ACK DATA
RECEIVE BP
ENERGY AND
TIME SAVE AT
TX & RX
RX (X-MAC)
SP SPSP
RX WAKE UP TIME
RE-
ACK DATA
TRANSMIT
SHORT PREAMBLE ADDRESS
WITHOUT TARGETED ADDRESS
TX (BN-
MAC)
RX (BN-
MAC) RX
S- W
SE-
ACK DATA
RECEIVE ABP
ENERGY AND TIME
SAVE AT TX & RX
ABP
AUTOMATIC
BUFFER PACKET
SE-
ACK
SENDER EARLY
ACKNOWLEDGEMENT
RE-
ACK
SHORT
WAKE UP
RECEIVER EARLY
ACKNOWLEDGEMENT
RX
S-W
RX WAKE
UP TIME
TIME
TIME
TIME
TIME
Figure 5: Comparison of timeline of duty cycle MAC protocols
The transmission cost of synchronized frame relates with
the precision of synchronization between the transmitter (TX)
and the receiver (RX). If the synchronization is not ideal, the
transmitter will not be able to know the accurate wake-up time
of the receiver. In our case, BN-MAC transmits short
preamble message before transmission of intra data frame in
order to determine the status of the receiver whether as busy or
idle. When the receiver receives short preamble message, it
acknowledges the arrival of the short preamble and gives a
clearance for sending the data packets. The duration of
sending Short preamble (SP) message depends on the clock
drift (CD) and occurrences of synchronization. The time for
short preamble messages is not exceeding CP because each
node gets up during each CP to check the transmission.
Duration of a short preamble can be calculated as follows:
We use clock drift (CD) and time for sending and
receiving the synchronized frame (SF). The synchronization
and clock drift are used by both sender and receiver that is
reason; we multiply by 2 for determining the time for short
preamble message (SF).
BN-MAC also introduces a concept of parent and child.
The node that transmits its clock to one-hop neighbor is called
as parent and the clock receiving one-hop neighbor node is
called as child. Nodes synchronized with clock often use only
short preamble messages without target address of node. Let
us assume that the energy consumed by parent and child node
is Ep and Ec respectively. Fsync is initial the transmission time
for synchronized frame. The average short preamble reception
time could be reduced to 50% because the receiving node
wakes up with respect to the stored schedule of the neighbor
nodes. Average energy consumed by parent and child node for
sending short preamble message can be calculated as:
In equation (3) parent node needs acknowledgement for
short preamble message that is reason clock drift and initial
transmission time for synchronized frame are doubled. In case
of child node in equation (4), node receives short preamble
message from parent, and for this job, it consumes energy.
Additionally, it also forwards its short preamble message to
other node then it becomes as parent and consumes further
energy as parent consumes in equation (3). Hence, all of nodes
follows the process of sending short preamble messages
accordingly.
It is clear that BN-MAC uses organized time
synchronization for scheduling before sending short preamble
asynchronously We already know that BN-MAC has edge
over low duty cycles long preamble enabled MAC protocols
as well as X-MAC. The strength of BN-MAC in consumption
of less energy and time is shown in Figure 6. It demonstrates
the soundness of BN-MAC in terms of less energy
consumption. Figure 7 shows the strength of BN-MAC as
compared with other low duty cycles MAC protocols in terms
of consumed time for sending short preamble in order to
access the channel for forwarding the data.
0 5 10 15 20 25 30 35
50 100 150 200 250
0
TIME IN (MINUTES)
BN-MAC
X-MAC
CONSUMPTION OF ENERGY (JOULES)
LPL
Figure 6: Consumption of energy for BN-MAC and low duty cycle MAC
protocols
The attractive feature of BN-MAC is that all nodes keep
the same time frame during synchronization and keep their
time slot 0. Each node in BN-MAC keeps its own local frame
that matches with the frame size of neighborhood. This is
reason that there is no chance of conflict contending with
neighbors. Nodes compete for CSMA equally during
contention phase because random exponential back off
preserves right of each node to fairly compete for scheduled
slots. In random exponential back off,
Intra semi synchronous communication is done inside the
region because BN-MAC protocol is purely designed for
region based network as many WSN application areas require
region based network.
0 15 30 45 60 75 90 105
2 4 6 810
0
NUMBER OF SENSORS
BN-MAC
X-MAC
CHANNEL ACCESS AND DATA SENDING TIME (SEC)
LPL
Figure 7: Channel accessing and data delivery time for BN-MAC and low
duty cycle MAC protocols
2.1.3. Inter synchronized transmission schedule
We have already discussed that BN-MAC is introduced for
WSN consisting of different regions. The previous section
highlights how to access the channel and forward the data
inside regions. This section explains how to send data within
regions and outside regions. Each region of WSN comprises
of Boarder Node (BN). The BN receives intra data packets
within region, and it forwards to outside of region. The BN of
each region follow schedule based method.
The BN first broadcasts three ‘hello’ messages to warn the
region nodes to be ready for getting the boarder node
indication signal (BNIS). BN does not wait to receive an
acknowledgement from all region nodes. If BN gets a single
acknowledgement from one region node, it assumes that
‘hello’ message is delivered successfully. Moreover, we have
already discussed that neighbor nodes exchange the schedule.
Thus, if any node is unable to get the ‘hello’ message, the
neighbor node informs other nodes at the time of exchanging
the schedule. Such way, each region node knows the schedule
of BN. BNIS consists of current tine, next distribution time,
next collection time and schedule for getting intra data packets
from the nodes of region given in Figure 8.
When BN intends to communicate with other BN of region,
it starts with inter synchronized transmission by using carrier
sensing. It makes possible to forward the message of request-
to-send (RTS), in response, it will get clear-to-send (CTS)
message from BN of other region. There is no hidden terminal
problem in BN-MAC because BNs of all regions broadcast the
messages to let each BN to know the schedule of every one.
HELLO
TX
(BN)
BNIS
HELLOHELLO
ACK
RX
REGION
NODE CHANNEL
WAIT TIME BSIF
TIME
TIME
TX
(BN)
RX
(BN)
TIME
TIME
CS RTS
CTS
BP
EIETHER SLEEP OR
AWAKE
BSIF
BDIF ACK
BUSY TIME WITHIN
REGION NODES
COMMUNICATION
WITH BN NODE
OF OTHER
REGION
ACK
ACKNOWLEDGEMENT
CTS
CLEAR-
TO-SEND
RTS
REQUEST-TO-
SEND
BP
BUFFER
PACKET
BNIS
BOARDER NODE
INDICATION
SIGNAL
BDIF
BROADCAST
DESTINATION
INTER FRAME
BSIF
BROADCAST
SOURCE INTER
FRAME
CS
CARRIER
SENSE
Figure 8: Inter synchronized transmission schedule with region node and
boarder nodes
After getting CTS, transmitter of BN forwards broadcast
source inter frame (BSIF) to other region. Receiver of BN
receives the broadcast destinations inter frame (BDIF) during
the interval having the CTS and RTS and finally
acknowledges the received packets. We have tested the
performance of BN-MAC and other hybrid protocols in terms
of throughput and an average energy consumption. We use
varying number of transmitting nodes at low duty cycle.
Figure 9 shows an average energy consumption for each
transmitter node that demonstrates that BN-MAC is also better
than other hybrid MAC protocols at low duty cycle.
0 2 4 6 8 10 12 14
2 4 8 10 12
0
Number of transmitting nodes
Average energy consumption for each node (Joules)
A-MAC
BN-MAC
Speck-MAC
ADC-SMAC
LPRT-MAC
ZMAC
Figure 9: Energy consumption on heavy traffic load using low duty cycle
When the number of transmitting nodes increases, energy
spent for each node is highly consumed for competing hybrid
MAC protocols as compared with BN-MAC. We observe that
other protocols consume 18% to 45% more energy than BN-
MAC during heavy traffic. The main reason of higher
consumption of energy is to use many continuous preamble
messages but BN-MAC uses short preamble to guarantee the
efficient delivery of data. Another reason of better
performance is to use of boarder node, which has automatic
buffering capacity to store packets rather than discarding.
2.1.4. Selection of boarder node
Border node is elected periodically on bases of boarder
node volunteer selection process (BNVSP) that is little bit
similar to [20]. BNVSP algorithm chooses border node on
basis of available energy and memory allocation resources. No
one node is compelled to be declared as boarder node on basis
of probability based calculation.
BN is decided on basis of energy level using BNVSP and
level of energy information (LEI) algorithm. The function of
LEI is to announce the level of energy for each node and
BNVSP decides to declare boarder node after comparison of
LEI of each node. When energy level of already working BN
goes down, shift of responsibility of one BN to another BN is
accomplished by using election flag bit (EFB). As, EFB
process alerts to nodes of each region to calculate their level of
energy. To reduce the overhead of shifting the responsibility
of one BN to another BN, BN-MAC uses a proactive method
to decide the next BN based available energy and memory
allocation resources.
The LEI of each node can be calculated as follows.
Where : Energy consumption of each sensor node in
each state. : Time spent in each state. Thus, 1 is radio on for
receiving traffic, 2 is radio off and 3 is transmitting the data
packets.
3. CONCLUSIONS
This paper introduces a new energy efficient BN-MAC
hybrid protocol with mobility support. The mechanism of BN-
MAC consists of TDMA and semi synchronous CSMA.
TDMA based features provide collision free access to the
medium and CSMA based features controls the overhearing
and congestion issues and provides faster access to the
medium for delivery of data. The mechanism of BN-MAC is
multi-featured that supports four application areas.
To demonstrate the soundness of the proposed BN-MAC,
we reported some interesting results by using ns2.35-RC7. We
have compared BN-MAC with known low duty cycle
protocols: X-MAC and LPL, and also compared with hybrid
protocols: Z-MAC, A--MAC, ADC-SMAC, LPRT-MAC and
Speck-MAC over WSN. Simulation results demonstrate that
BN-MAC has consumed less energy as compared with other
competing MAC protocols. BN-MAC has saved 18% to 45%
more energy than other hybrid MAC protocols. In the future,
we plan to compare different features of BN-MAC and other
MAC protocols.
REFERENCES
[1] M.Wei et al., “Optimality Analysis of Sensor-Source Geometries in
Heterogeneous Sensor Networks”, IEEE Trans. Wireless Commun.
Vol.12,no.4, pp. 1958-1967,2013.
[2] A.Razaque and K.M.Elleithy,”Automated energy saving (AES)
paradigm to support pedagogical activities over wireless sensor
networks” In proc. of ACM/Springer on ubiquitous computing and
ambient intelligence (UCAmI), December 3-5, 2012,pp. 512-519.
[3] K. J.Yatish and Y. Mohamed,”Autonomous recovery from multi-node
failure in Wireless Sensor Network”, GLOBECOM ,2012, pp. 652-657.
[4] B. Paolo et al.,“ A survey: Mobile social networking middleware”,
International Journal Elsevier for Pervasive and Mobile Computing,
vol.9,no.4,pp. 437-453 , 2013.
[5] Y.Liu and M.Lionel, “.A New MAC Protocol Design for Long-term
Applications in Wireless Sensor Networks”, In Proc. of the Parallel and
distributed systems,2007, pp. 1-8.
[6] J.A.Afonso et al., “ MAC Protocol for Low-Power Real-Time Wireless
Sensing and Actuation”, In Proc. of the 11th IEEE International
Conference on Electronics, Circuits and Systems, Nice, 10-13 December
2006, pp. 1248-1251.
[7] B.Michael et al.,”X-MAC: A Short Preamble MAC Protocol for Duty-
cycled wireless sensor networks”, Trans. ACM, pp. 307-320, 2006.
[8] C.Wu et al., “Rigidity guided localization for mobile robotic sensor
networks”, International. Journal of Ad Hoc and Ubiquitous Computing,
vol.6,no.2,pp.114-128.
[9] J.Bohn et al.,”Social, Economic, and Ethical Implications of Ambient
Intelligence and Ubiquitous Computing , Springer trans. Ambient
Intelligence, vol.10,no.5, October 15, 2004.
[10] C.A.B.Ioannis et al., “Fault tolerant and efficient data propagation in
wireless sensor networks using local additional network information”,
Elsevier International Journal of Parallel and distributed computing, vol.
67,pp. 456–473, 2007.
[11] K. Jamieson1 et al., “Sift: A MAC Protocol for Event-Driven Wireless
Sensor Networks”, In proc. Springer LNCS 3868, 2006, pp. 260–275.
[12] A.Razaque and K,M. Elleithy, “Automatic energy saving (AES) model
to boost ubiquitous wireless sensor networks (WSNs), International
Journal of computers and technology (IJCT),vol.10, no.5 ,pp. 1640-
1645, August, 2013.
[13] D.Debraj et al., “ EAR: An energy and activity-aware routing protocol
for wireless sensor networks in smart environments”, Comput. J. vol.55,
no.12, pp.1492-1506, 2012.
[14] N.B.Ahmed et al.,“A Cooperative Low Power MAC Protocol for
Wireless Sensor Networks”, In proc. of IEEE ICC, 2011.
[15] S.Liqi and O.F.Abraham, “.TDMA Scheduling with Optimized Energy
Efficiency and Minimum Delay in Clustered Wireless Sensor
Networks”, IEEE Trans. Mobile Computing, Vol. 9, No. 7, pp. 927-939,
July 2009.
[16] W.Dargie and C. Poellabauer,”Fundamentals of wireless Sensor
networks”, Wiley Series on Wireless Communications and Mobile
Computing, January 10, 2011.
[17] K.J.Wong and D. Arvind, “Low Power Decentralized MAC Protocols
for Low Data Rate Transmissions in Specknets”, In Proc. of ACM
International Workshop on Multihop Ad-hoc Networks: From Theory to
Reality, Florence, Italy, 2006, pp.1-9.
[18] R.Injong et al.,”ZMAC: a Hybrid MAC for Wireless Sensor Networks”,
In proc. of ACM for SenSys0 5, San Diego, California, USA, November
2–4, 2005.
[19] J.Zhao and R,Govindan, “Understanding packet delivery performance in
dense wireless sensor networks”, In Proc. of ACM, Los Angeles, CA,
November 5-7, 2003.
[20] A.H.Nakashima and J.C. Augusto, “.Handbook on Ambient Intelligence
and Smart Environments”, Springer Verlag, 2009.
[21] V.Rajendran,K.Obraczka, J.J. Garcia-Luna-Aceves, “Energy Efficient,
Collision-Free Medium Access Control for Wireless Sensor Networks”,
In proc. of ACM SenSys 03, Los Angeles, California, 5-7 November
2003,pp.181 – 192.
[22] Ziqiang,” A. Medium Access Control Protocol with Dynamic Duty
Cycle in Wireless Sensor Network”, International Journal of Future
Computer and Communication, Vol. 1, No. 1, June 2012.
[23] Y.Kim, H.Shin, and H.Cha , “Y-MAC: An Energy-efficient Multi-
channel MAC Protocol for Dense Wireless Sensor Networks “, In
proceedings of IEE international conference on 2008 International
Conference on Information Processing in Sensor Networks, pp.53-63,
2008.
