International Journal of Science and Advanced Technology (ISSN 2221-8386)
Volume X No X Month 20XX
http://www.ijsat.com
A TRENCHANT HYBRID-MAC PROTOCOL FOR
RESOURCE CONSTRAINED WIRELESS SENSOR
NETWORKS
Harshavardhan
Balaji Kannapan
Post Graduate Research Scholar
Department of Computer science & Engineering
Sri Venkateshwara college of Engineering, B’lore
Assistant professor
Department of Computer science & Engineering
Sri Venkateshwara College of Engineering,B’lore
Abstract— Wireless sensor networks are appealing to
researchers due to their wide range of application potential in
areas such as target detection and tracking, environmental
monitoring, industrial process monitoring, and tactical systems.
However, low sensing ranges result in dense networks and thus it
becomes necessary to achieve an efficient medium-access
protocol subject to power constraints. In the area of wireless
sensor networks, achieving minimum energy consumption is a
very important research issue. A number of energy efficient
protocols have been proposed, mostly based on a layered design
approach, which means that they are focused on designing
optimal strategies for “single” layer only. In this paper, we
present the Trenchant Hybrid MAC (TH-MAC), a low power
with quality of service guaranteed medium access control
protocol for wireless sensor networks (WSNs). The TH-MAC
achieves high energy efficiency under wide range of traffic load.
It ensures shorter latency to critical and delay-sensitive packets.
The TH-MAC protocol achieves high channel utilization during
high traffic load without compromising energy efficiency.
cheaper short-range radio communication. Thanks to their
essential characteristics of energy and likelihood of
failures, wireless sensor networks need a style of the
economical mac protocol. Especially, the first goal of a
projected mac protocol is to cut back energy consumption,
as a result of a speedy power drain of sensor node could
halt all the essential functions of the sensor network.
The protocols designed for WSNs principally rely
on the applications that the network has been build. All the
same, in most of the applications, one among the intense
challenges is the way to increase the network time period
that is currently restricted by the energy unnatural in
sensing element nodes. Many famous factors area unit
concerned within the energy loss of nodes: collisions, idle
listening,
protocol
overhead,
overhearing
and
retransmissions. The radio module of a sensing element
node uses most of the ability. The node unremarkably turns
its radio off, goes to sleep mode to save lots of energy, and
wakes up per its preset schedule to transmit information.
This methodology is termed as duty cycling or a sleep
scheduling, that is greatly planned to be used within the
Medium Access control (MAC) protocol of wireless sensor
networks.
Keywords- access protocols, broadcast communication,
energy conservation, quality of service, scheduling, wireless
sensor networks, CSMA, TH-MAC protocol, TDMA approach
I.
INTRODUCTION
Each and every shared wireless channel wants a
medium access control (MAC) protocol to intercede access
to the channel. Over the past many years, several mac
protocols are developed and a number of other are in use of
wireless networks nowadays. Wherever these protocols
work well for traditional knowledge workloads, they are
not appropriate in rising wireless sensor networks
wherever the sort of information transmissions and
application needs are substantially different. This project
poses that wireless sensor networks need a replacement
check up on mac protocol style, and proposes a
replacement protocol that works pretty smart during this
downside domain by taking advantage of application needs
and knowledge characteristics.
A properly designed mac protocol may end up in
low power consumption and thus increase the network life.
Wireless sensor networks may be a new
generation of sensing element networks and contains a
terribly big selection of applications, their development
and application can motivate an improved impact in human
life and production of all areas. However, the foremost
vital limitation of the WSN is that each sensing element
node depends on a inbuilt battery, that is tough to recharge
or replace. Minimizing superfluous energy consumption is
thus a really vital challenge that should be addressed at
each layer of the protocol. Our focus are going to be on
medium access control (MAC) as a result of mac will
control the on and off states of the wireless interface to
boost energy potency.
Wireless sensor network consists of a various
good sensors equipped with restricted battery power and
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International Journal of Science and Advanced Technology (ISSN 2221-8386)
Volume X No X Month 20XX
http://www.ijsat.com
Most of the mac protocols projected for these WSNs are
primarily based upon the utilization of one channel. Such
kind of mac protocols, particularly in high-density
deployments, might increase collisions also as Latency,
and ultimately minimize the network life. many multichannel mac protocols are projected recently with varied
objectives, e.g., handling burst traffic, fairness,
dependability in knowledge assortment, evading external
interference, up outturn, and end-to-end delay. However,
energy saving continues to be a vital issue.
II.
in S-MAC (say 100 percent sense and ninetieth sleep), it's
a variable duty cycle. the thought is comparable thereto of
a screen-saver of pc. even as the screen-saver starts when
an exact time of inactivity, the node switches itself to
sleeping mode once no active event has occurred for a preassigned fundamental measure. The active event is a
receiving of some knowledge, expiration of some timer,
sensing of the channel, information of associate degree
close at hand knowledge reception through neighbors’
RTS/CTS then on. Synchronization of schedules is
achieved in an precisely similar manner as S-MAC through
the theme named as virtual cluster.
EASE OF USE
Wireless sensor networks have attracted a
considerable attention from the researchers in the recent
times. Though the initial research came from military
applications, the advancements in the field of pervasive
computing have led to possibilities of a wide range of
civilian, environmental, bio-medical, industrial and other
applications. In order to practically realize such networks,
Medium access control (MAC) is one of the basic
protocols that have to be appropriately defined. The
previous chapter presented some of the fundamental issues
underlying the design of MAC protocols for sensor
networks. In this chapter, we continue the discussion and
present upon comprehensive survey of other MAC
protocols studied for wireless sensor networks. We first
present protocols that are based on random access
techniques such as Carrier Sense Multiple Access
(CSMA). These include the Sift protocol, the T-MAC
protocol and other protocols. The next set of protocols are
based upon static access and scheduling Mechanism.
C. SIFT: AN EVENT-DRIVEN MAC PROTOCOL
The Sift protocol exploits the event driven nature
of sensing element networks for raincoat protocol style.
This work points out that the rivalry among the sensing
element nodes is usually spatially related. This implies that
at a given time, solely a group of adjacent ( s⁄s≤N) sensors
have knowledge to transmit and this can be possibly to
intend detection of some specific event. Thus, rivalry
resolution could also be restricted to those s sensors instead
of the whole set of N sensors. The protocol adopts a typical
random access protocol like CSMA or CSMA/CA and uses
a set size rivalry window with a non-uniform likelihood
distribution for selecting the rivalry slot for a node.
At system low-level formatting, each node uses an
outsized estimate of a node population and thence
correspondingly little transmission probabilityP_s, every
node additionally ceaselessly monitors the competition
slots and reduces the node count estimate once each
competition slot that goes free. That is, a free slot is taken
as a sign of less variety of sensors than assumed. Likewise,
the node will increase its transmission chance
multiplicatively once every free slot. Therefore the
competition is reduced to geometrically decreasing variety
of nodes for identical variety of competition slots. This is
often the core plan of Sift whereby the protocol sifts the
slot-winner node from the others.
A. TRAFFIC ADAPTIVE MEDIUM ACCESS
PROTOCOL (TRAMA)
The main aim of TRAMA protocol is to supply an
entire collision free medium access and therefore achieving
vital energy saving. it's primarily a scheduled primarily
based mac protocol with the random access part for
establishing the schedules. TRAMA is predicated upon
switching the nodes to an occasional power mode to
comprehend the energy savings. A Protocol has completely
different phases or parameters namely: Neighbor Protocol
(NP), Schedule Exchange Protocol (SEP) and adaptative
Election rule (AEA). NP uses a random access period to
collect one-hop and two-hop neighbor data. sep helps in
establishing the schedules for a given interval among the
one-hop and two-hop neighbors. Finally, AEA decides a
winner of the given slot and conjointly facilitates the use of
unused slots.
III.
SYSTEM DESIGN
We initial outline the terminology utilized in this
paper. A Timeslot or Slot or a Frame is outlined because
the periodic interval, that consists of an active period and a
sleep period. A duty cycle is that the proportion or ratio of
active amount to the whole cycletime (frame length). An
arrangement slot is outlined as a slot expressly dedicated to
a pair of nodes to speak with one another. Throughout
rendezvous, a node forms a channel for transmission and
reception with one in all its neighbor. The term channel
here refers to a period or slot as critical frequency or code.
B. T-MAC Protocol
The T-MAC protocol makes an attempt to boost
on the performance of the S-MAC protocol. It proposes
victimization the dynamic duty cycle as against a hard and
fast one in S-MAC to higher scale back the idle listening
periods. It additionally introduces some extra options
delineated below.
Since idle listening is that the major supply of
overhead, TMAC like S-MAC, maintains the sleep-sense
cycle. but rather than having a hard and fast duty cycle like
TH-MAC classifies packets in line with their
importance (i.e. delay requirements) and keep the packets
into the suitable queue. The supply node is aware of the
degree of importance of the detected information and
consequently the application layer sets the priority.
Application layer will it by appending one further bit at the
top of the info packet. The mechanism of TH-MAC relies
on dividing the communication time into fastened length
slots or frames. The contents of every slot are shown in
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International Journal of Science and Advanced Technology (ISSN 2221-8386)
Volume X No X Month 20XX
http://www.ijsat.com
Fig3.1. Every slot begins with a synchronise period. The
aim of the synchronise packet is to keep up
synchronization between the nodes inside identical virtual
cluster. Consequent a part of the active amount of the
frame is reservation slot that is employed for the info slot
reservation and therefore the last half is employed for
information and ACK transmission by sensor nodes.
case of such state of affairs owner can vie among one
another for obtaining access of the medium.
Now, every node will build a number of its in
hand slot as a meeting slot with that it will send message to
its neighbor solely. The rendezvous slots will be calculated
by every node regionally victimisation clock arithmetic, as
modulo m. the worth of m is about in step with the system
needs, i.e. network load, delay, message buffer size etc.
and also the value of m are forever multiple of n. For the
sake of quantifiability, the worth that we have a tendency
to use in modulo operation i.e., m are forever larger than
the worth of n of a specific node. thus once a brand new
node needs to affix within the network, a minimum of
there'll be some slots that don't seem to be victimization as
rendezvous and it'll be used for the quantifiability.
3.1 Contents of Frame for proposed TH-Mac Protocol
A. Neighbor Discovery, Clustering and Synchronization
Stage
Frame synchronization is finished by virtual
clustering, as delineate within the S-MAC protocol. Once
node involves life, it starts by waiting and listening. If it
hears nothing for a particular period, it chooses a frame
schedule and transmits a synchronise packet. The
synchronise packet contains the time till following frame
starts. If the node throughout initiate hears a synchronise
packet from another node, it follows the schedule in this
synchronise packet and transmits its own synchronise
consequently. Nodes channel their synchronise once in an
exceedingly whereas. Once a node contains a schedule
however it hears synchronise with a special schedule from
another node, it adopts each schedule. Adopting each
schedule ensures the thriving communication between the
nodes of various schedules. The delineate synchronization
theme, that is named virtual bunch, urges nodes to make
clusters with an equivalent schedule. So, all the nodes
within the networks needn't to follow an equivalent
schedule. During this virtual cluster creation, every node
creates the one hop neighbor list and with exploitation
these a node will simply constitutes the 2 hop neighbor list.
subsequently every node is given an id specified inside a 2
hop neighbor the id is exclusive.
C. State Machine
The state machine of the IH-MAC protocol is
shown within the Fig. 3.2. Throughout the sleep state the
node close up its radio and begin a timer whose period is
predefined in step with the duty cycle of the protocol
considerately of the existence of rendezvous
communication between any combine of nodes. Once the
timer expires, the node goes to wake-up state. It activates
its radio and switches to concentrate to the information
channel and its goes to idle listening state. If the node has
any information to send or receive it goes within the
CSMA/CA state otherwise when trip it goes to sleep state.
If the sender node wins the contention each the sender and
therefore the supposed receiver attend the T x/Rx state and
attend sleep state when winning communication. Nodes
that fail contention attend sleep state.
B. Slot Assignment
Each slot in TH-MAC consists of a set length
sync period, a fixed length data period and a sleep period
that depends on the duty cycle as in Fig. 4.1. The duty
cycle ought to be chosen in such the way that the sleep
amount of a slot is massive enough to transmit an
information packet beside ACK. All nodes are allowed to
transmit in any slot however the node that encompasses a
crucial data (with high priority) can get the priority. If no
such data is out there then the owners of a slot can get the
priority. Priority may be ensured by selecting rivalry
window size.
3.2 State Diagram of Proposed TH-Mac Protocol
D. Transmission Power Adjustment
The power adjustment options of TH-MAC
permit the sensor nodes to befittingly vary the transmission
power to scale back energy consumption. TH-MAC
transmits the RTS and CTS packets with most power
Pmax. once receiver node receives an RTS packet, it
responds with a CTS packet at usual most power level
Pmax. once the supply node receives this CTS packet, it
calculates Pdesired supported the received power level Pr
and transmitted power level Pmax as
The owner calculation is performed by every
detector node regionally by straightforward clock
arithmetic (modulo n). Wherever n represents the quantity
of neighbors nodes, at intervals 2 hop neighbor of a node.
The worth of n won't be constant for all nodes during a
virtual cluster. It ought to be noted here that victimisation
modulo may end in multiple owners of a slot, since totally
different node IDs will map to constant slot variety. Just in
𝑷𝒅𝒆𝒔𝒊𝒓𝒆𝒅 =
3
𝑷𝒎𝒂𝒙
× 𝑹𝒙𝒕𝒉𝒓𝒆𝒔 × 𝒄
𝑷𝒓
International Journal of Science and Advanced Technology (ISSN 2221-8386)
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Where Rxthres is that the minimum necessary
signal strength and c may be a constant. The supply node
uses power level Pdesired to transmit information packet.
Similarly, receiver uses the signal power of received RTS
packet to work out the ability level to be used Pdesired, for
the ACK packet. This technique assumes the attenuation
between sender and receiver nodes to be a similar in each
directions. It conjointly assumes the amplitude at nodes to
be below a definite predefined threshold worth.
Now energy consumption throughout tSIM will
be expressed by
𝒆 = 𝒏𝑻𝑿(𝑾) × 𝒆𝑻𝑿(𝑾) + 𝒏𝑻𝑿(𝑹) × 𝒆𝑻𝑿(𝑹)
+ 𝒏𝑹𝑿(𝑾) × 𝒆𝑹𝑿(𝑾) + 𝒏𝑹𝑿(𝑹)
× 𝒆𝑹𝑿(𝑹) + 𝒕𝑶𝑯 × 𝒆𝑶𝑯 + 𝒕𝑰𝑫𝑳𝑬
× 𝒆𝑰𝑫𝑳𝑬 + 𝒕𝑺𝑳𝑬𝑬𝑷 × 𝒆𝑺𝑳𝑬𝑬𝑷
+ 𝒕𝑻𝑹𝑨𝑵𝑺 × 𝒆𝑻𝑹𝑨𝑵𝑺
Since TH-MAC permits information transmission
between just one combine of nodes in an exceedingly slot
and every one the neighbors of each sender and receiver
sleep throughout transmission, it overcomes the
shortcomings of aforesaid technique, like accrued collision
and degradation of network output.
Since TH-MAC has the probation of adjusting
transmission power we use maximum transmission power
as ETX(max) and right transmission power as, ETX(right).
E. ENERGY CONSUMPTION ANALYTICAL MODEL
An analytical model for the energy consumption
of nodes for TH-MAC is explained during this section. For
simplicity we tend to think about the case wherever a
detector node is either in broadcast programming mode or
during a link programming mode. Let d be the duty cycle
and tSIM be the simulation time and tTX, tRX, tOH,
tIDLE, tSLEEP, tTRANS are denoted because the time
spent for sending, receiving, overhearing, idle listening,
sleep, and radio transitions throughout sleep to wakeup
state of a detector node, severally.
𝒆𝑻𝑿(𝑾) = 𝑬𝑻𝑿(𝑴𝑨𝑿) × 𝒕𝑺𝒀𝑵𝑪_𝑹𝑻𝑺 + 𝑬𝑻𝑿(𝒓𝒊𝒈𝒉𝒕)
When a sensor node transmits a packet, it sends
SYNC, RTS, DATA and it receives CTS and ACK. So, for
transmitting a packet energy consumed by a transmitting
node is
× 𝒕𝑫𝑨𝑻𝑨 + 𝑬𝑹𝑿 × 𝒕𝑪𝑻𝑺 + 𝑬𝑹𝑿
× 𝒕𝑨𝑪𝑲
𝒆𝑻𝑿(𝑹) = 𝑬𝑻𝑿(𝒓𝒊𝒈𝒉𝒕) × 𝒕𝑺𝒀𝑵𝑪 + 𝑬𝑻𝑿(𝒓𝒊𝒈𝒉𝒕)
So, tSIM can be expressed as
× 𝒕𝑫𝑨𝑻𝑨 + 𝑬𝑹𝑿 × 𝒕𝑨𝑪𝑲
𝒕𝑺𝑰𝑴 = 𝒕𝑻𝑿 + 𝒕𝑹𝑿 + 𝒕𝑶𝑯 + 𝒕𝑰𝑫𝑳𝑬 +
𝒕𝑺𝑳𝑬𝑬𝑷 + 𝒕𝑻𝑹𝑨𝑵𝑺
IV.
RESULTS & DISCUSSION
In this section, we investigate the performance of
the proposed IH-MAC protocol. We have simulated with
MIXIM a simulator for Wireless Sensor Networks. Which
is developed on the discrete event simulator OMNET++ .
In the simulation setup, we take 5 nodes distributed in a
uniformly random way on a 500×500 m area grid. The
nodes are static and the sink node is chosen on the bottom
right corner of the network grid. The duty cycle is chosen
15 percent.
And
𝒕𝑺𝑰𝑴 = 𝒕𝑺𝑳𝑶𝑻 × 𝑵
Here, N is total number of slots during time tSIM.
Again
𝒕𝑺𝑰𝑴 = 𝒕𝑾 + 𝒕𝑹
where tW and tR represent time period while THMAC operates in broadcast scheduling mode and link
scheduling mode respectively.
We compare the performance of our proposed IH-MAC
protocol with the standard B-MAC protocol. We took BMAC is widely accepted Medium Access Control protocol
for Wireless Sensor Network. Performance metrics used in
evaluation of IH-MAC protocol are Energy consumption,
and Average Packet Latency. Energy consumption of
sensor nodes for TH-MAC and B-MAC are shown in Fig.
7.3. We vary the packet generation interval from 1 to 10
seconds. We see that energy consumption per bit of THMAC is less than the energy consumption of B-MAC. The
reason behind consumption of less energy is the use of
adjusted transmission power in our proposed TH-MAC
which is explained in Section III-D Energy consumption in
rendezvous slot is less than the energy consumption of a
slot of B-MAC as explained in Section III-E of this paper.
And with comparison of B-MAC, TH-MAC performs
better with the heavy traffic.
Let nH, nTX, nRX, nOH, represents the total
number of times that a node hears, transmits, receives, and
overhears during tSIM.
A sensing element node consumes energy by
transmittal (eTX), receiving (eRX), overhearing (eOH),
and idle listening (eIDLE) throughout the awake state. and
through the sleep state terribly less energy is consumed.
throughout transition (eTRANS) from sleep state to active
state energy is additionally consumed. Since our IHMAC
protocol operate each in broadcast programing and link
programing (Rendezvous) and that we have used power
adjustment technique, therefore transmittal energy is more
divided into 2 class, while not rendezvous, eTX(W) and
with rendezvous, eTX(R). Similarly, receiving energy will
be divided into eRX(W) and eRX(R).
4
International Journal of Science and Advanced Technology (ISSN 2221-8386)
Volume X No X Month 20XX
http://www.ijsat.com
CONCLUSION
This paper presents TH-MAC; a novel energy
efficient hybrid based medium access control protocol for
wireless sensor networks. There are three novel
contributions in this paper. Firstly, our proposed TH-MAC
protocol introduces the use of the concept of link
scheduling and broadcast scheduling together. To the best
of our knowledge, in a single protocol, TH-MAC is the
pioneer which exploits these two concepts (pairwise
TDMA and broadcast TDMA) together to obtain optimum
resource utilization. Secondly, we successfully identified
(and achieved) the possibility of enhancement of the scope
of parallel transmission by transmitting a signal (wireless)
with the appropriate power (adjusted power). The third
novel contribution is the introducing the idea and
realization of a decentralized TDMA. We successfully
showed that without any centralized scheduling how
TDMA can run smoothly (we use clock arithmetic here).
We believe these novel ideas will significantly contribute
not only in the area of protocol design of WSNs but also
the protocol design of any wireless Ad-hoc network.
Figure 4.1: Parameter assignment for Proposed TH-MAC
Protocol
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