Download Performance Analysis of Topological Variation in Personal Area

ISSN : 0976-8491 (Online) | ISSN : 2229-4333 (Print)
IJCST Vol. 3, Issue 4, Oct - Dec 2012
Performance Analysis of Topological Variation in Personal
Area Network using ZigBee Wireless Sensors
1
1,2,3
Lovish Jaiswal, 2Jaswinder Kaur, 3Gurjeevan Singh
Dept. of ECE, SBS, State Technical Campus, Ferozepur, Punjab, India
Abstract
ZigBee (IEEE 802.15.4-2006 standard) is a category in the IEEE
802 family, along with some of the well-known protocols such as
Wi-Fi, Bluetooth which uses the 2.4 GHz industrial, and scientific
and medical (ISM) radio band. ZigBee also utilizes 868 MHz
and 915 MHz in different parts of the world according to local
standards. Unlike Wi-Fi and Bluetooth, ZigBee was developed
for low-rate WPAN (LR-WPAN) which feature long battery life
by having low data rates. In ZigBee WSN’s, topology plays an
important role and is one of the most significant parameter in
Wireless Sensor Networks. In this paper we evaluate the effect
of topologies variation i.e. Tree, Star and Mesh on throughput,
end to end delay, number of hop and network load using ZigBee
wireless sensors by means of OPNET modeller 14.5.
technologies will be a significant one, especially as reliability is
an important requirement. There are three main nodes used in
ZigBee Sensor Networks i.e. ZigBee Coordinator, ZigBee Router
and ZigBee Sensor End Devices [12].
Keywords
IEEE-802.15.4, ZigBee WSN, Topology, MAC Layer, OPNET
Modeler, Throughput, Load, Delay, No. of Hop
I. Introduction
ZigBee is based on the IEEE 802.15.4 standard along with other
protocols like Wi-Fi and Bluetooth. ZigBee is a specification for a
suite of high level communication protocols based on an IEEE 802
standard for personal area networks. The ZigBee protocol defines
three types of wireless nodes – Personal Area Network (PAN)
coordinator, full function device and reduced function device. The
ZigBee protocol can support over 64,000 nodes and can operate
in three network topologies: Star, Tree and Mesh. The large
amount of supported nodes is another appealing characteristic,
specifically in industrial applications. ZigBee was developed by
IEEE 802.15.4 Task Group and ZigBee Alliance. ZigBee alliance
is responsible for ZigBee standard which uses the transported
services of the 802.15.4 network specification just like TCP/IP
uses the IEEE 802.11b network specification. The standard was
developed to meet the following principal need of low cost, ultralow power consumption, use of unlicensed radio bands, cheap
and easy installation, flexible and extendable networks [1]. The
primary goal of the wireless sensors is to gather relevant data
from their surrounding and, subsequently, to route the gathered
data to a central processing node, commonly referred to as sink. A
simple ZigBee Network is shown in figure1. The sink is generally
considered to have far superior.
II. ZigBee IEEE 802.15.4 Standard
The goal of the IEEE 802.15.4 standard is to provide a low-power,
low-cost and highly reliable protocol for wireless connectivity
among inexpensive, fixed and portable devices [3-5]. These devices
can form a sensor network or a Wireless Personal Area Network
(WPAN). This last type of network is used for communication
among devices (including telephones and personal digital
assistants) close to one person. The standard defines a physical
layer and a MAC sub layer. Three different frequency ranges are
offered. The most important one is the 2.4 GHz range. This is the
same range as 802.11b/g and Bluetooth. Consequently, the issue
of interference and thus coexistence between the different wireless
706
International Journal of Computer Science And Technology
Fig. 1: Generalized ZigBee Network
•
•
•
ZigBee coordinator is intended for starting the network and
choosing the key network parameters. There is one single
coordinator in any given ZigBee network. In ZigBee-based
WSNs, the responsibility of network coordinator is typically
given to the sink node.
ZigBee routers are devices capable of routing data. In the case
of many-to-one multi-hop ZigBee-based WSNs, (ordinary)
sensor nodes are likely to assume the role of network routers,
in addition to performing the sensing function.
ZigBee end-devices have no routing capability – these devices
rely on their parents, the coordinator or routers, to transmit/
route their packets. In our study, the presence of devices
corresponding to this (very low level) of functionality has
not been considered.
III. ZigBee Applications
ZigBee standard provides network, security, and application
support services operating on top of the IEEE 802.15.4 Medium
Access Control (MAC) and Physical Layer (PHY) wireless
standard. ZigBee applications include:
• Home and office automation
• Industrial automation
• Medical monitoring
• Low-power sensors
• HVAC control
w w w. i j c s t. c o m
ISSN : 0976-8491 (Online) | ISSN : 2229-4333 (Print)
• Plus many other control and monitoring uses.
ZigBee is a low-cost, low-power, wireless mesh networking
standard. The low cost allows the technology to be widely
deployed in wireless control and monitoring applications, the
low power-usage allows longer life with smaller batteries, and
the mesh networking provides high reliability and larger range [8]
[19]. The ZigBee wireless networking standard fits into a market
that is simply not filled by other wireless technologies. The market
category ZigBee serves is called, wireless sensor networking and
control or simply “wireless control”.
IV. IEEE 802.15.4/ ZigBee Architecture
802.15.4 is a packet-based radio protocol. It addresses the
communication needs of wireless applications that have low
data rates and low power consumption requirements. It is the
foundation on which ZigBee is built. Fig. 2 shows a simplified
ZigBee stack, which includes the two layers specified by 802.15.4:
the physical (PHY) and MAC layers [2,6,14].
IJCST Vol. 3, Issue 4, Oct - Dec 2012
node can have 240 separate application objects. An application
object may also be referred to as an endpoint (EP).
2. ZigBee Device Object (ZDO)
A ZigBee device object performs control and management of
application objects. The ZigBee device objects represents the
ZigBee node type of the device; defining the nodes role on the
network. It is resident on all ZigBee nodes and provides generic
ZigBee device functions
C. Physical Layer
The physical layer is responsible for data transmission and
reception using certain radio channel according to a specific
modulation and spreading techniques. This layer manages the
physical RF transceiver; it performs channel selection as well
as energy and signal management routines. The physical layer
performs modulation on outgoing signals and demodulation on
incoming signals. It transmits information and receives information
from a source.
D. MAC Layer
The MAC layer determines source and destination addressing
of frames and is extracted from the IEEE 802.15.4 standard. To
provide reliable data transfer, this layer provides multiple access
control in the form of Carrier Sense Multiple Access and Collision
Avoidance, to transmit beacon frames for synchronization,
and to provide reliable transmission. It also provides per-hop
acknowledgments and some of the commands for joining and
forming a network.
Fig. 2: ZigBee Layer Architecture
A. Application Layer
The application layer is the highest-level layer defined by the
ZigBee specification. This layer contains applications running
on the ZigBee network and thus provides the effective interface
to the user. A single node can support 240 applications, where
application number 0 is reserved for the ZigBee Device Object.
These give the device its functionality - essentially an application
converts input into digital data, and/or converts digital data into
output. A single node may run several applications.
B. Application Support Sub layer (APS)
The application support sub layer (APS) provides the services
necessary for application objects (endpoints) and the ZigBee
Device Object (ZDO) to interface with the network layer for data
and management services [9]. Some of the services provided by
the APS to the application objects for data transfer are request,
confirm, and response.
1. Application Object (Endpoint)
An application object defines input and output to the APS. For
example, a switch that controls a light is the input from the
application object, and the output is the light bulb condition. Each
w w w. i j c s t. c o m
E. Network Layer
The network layer is located between the MAC layer and application
support sub layer. The network layer is responsible for network
management and addressing, message routing, route discovery
as well as security features Responsibilities of the network layer
include mechanisms used to associate to and disassociate from a
network, apply security to outgoing frames, and routing frames
to intended destinations.
V. ZigBee Topologies
“Topology” refers to the configuration of the hardware components
and how the data is transmitted through that configuration. They
describe the physical and logical arrangement of the network
nodes. There are three network topologies i.e. Star topology, Mesh
topology, Tree topology, we explain all these topology discussed
below:
A. Star Topology
The star topology consists of a coordinator and several end devices
(see figure 2.8). In this topology, the end device communicates
only with the coordinator. Any packet exchange between end
devices must go through the coordinator. If a ZED (ZigBee end
devices) needs to transfer data to another ZED, it sends its data to
the ZC (ZigBee Coordinator), which subsequently forwards the
data to the intended recipient [10]. The main advantages of star
topology are its simplicity and predictable and energy efficient
behaviour. The drawbacks are limited scalability and ZC as a
single point of failure.
B. Mesh Topology
A mesh topology offers multiple paths for messages within the
network; this lends itself to greater flexibility than other topologies.
International Journal of Computer Science And Technology 707
ISSN : 0976-8491 (Online) | ISSN : 2229-4333 (Print)
IJCST Vol. 3, Issue 4, Oct - Dec 2012
If a particular router fails, then ZigBee self-healing mechanism will
allow the network to search for an alternate path for the message
to be passed. Mesh topology is highly reliable and robust. The
advantage being that if any individual router becomes inaccessible,
alternative routes can rediscovered and used The limitation of
this topology has a higher communications overhead than the
star topology, which can result in increased latency and lower
end-to-end performance.
C. Tree Topology
A Tree topology consists of a Co-ordinator, to which other nodes
are connected as follows:
1. The Co-ordinator is linked to a set of Routers and End Devices
- its children.
2. A Router may then be linked to more Routers and End Devices
- its children. This can continue to a number of levels.
This hierarchy can be visualised as a tree structure with the
Co-ordinator at the top, as illustrated in the diagram below. For
every child router connected, additional child routers can also be
connected, creating different levels of nodesIn order the messages
to be passed to other nodes in the same network, the source node
must pass the messages to its parent, which is the node higher-up by
one level of the source node, and the message is continually relayed
higher up in the tree until it is passed back down to the destination
node. Because the number of potential paths a message can take is
only one. A Router therefore can be used in place of an End Device
in a Tree network, but the message relay functionality of the Router
will not be used -only its applications will be relevant.
Fig. 3: Star Topology
In this paper we evaluated above three topologies by creating
the network model and simulation environment using opnet
modeler 14.5 as a means to compare simulation results. The
simulation shows the likely behaviour of the system based on its
simulation model under different environment. OPNET simulation
tool provides a complete development environment to support
modelling of communication networks and Sensor systems. It
supports three types of topologies: star, mesh and cluster-tree
topology with beacon disabled mode, where communication takes
place between a central controller – ZigBee PAN Coordinator,
ZigBee Routers and ZigBee Sensor devices.
Table 1:
Parameters
No. of Sensor Nodes
Star
50
Mesh
50
Tree
50
Transmit Power
0.05
0.05
0.05
Number of
Retransmissions
5
5
5
Maximum Backoff
exponent
1
1
1
5
5
5
-80
-80
-80
Disabled
Enabled
Disabled
Transmission band (MHz) 2450
2450
2450
Transmit power
(sensor nodes)
0.4
0.4
0.4
Transmit
power(coordinator)
0.5
0.5
0.5
Packet size
1024
1024
1024
Packet inter arrival time
Constant
(0.5)
Constant
(0.5)
Constant
(0.5)
Maximum number
Backoff exponent
Packet power Threshold
Mesh Routing
Fig. 4: Mesh Topology
Fig. 5: Tree Topology
Fig. 6: ZigBee Process Model
VI. Simulation Model & Scenario
708
International Journal of Computer Science And Technology
w w w. i j c s t. c o m
ISSN : 0976-8491 (Online) | ISSN : 2229-4333 (Print)
IJCST Vol. 3, Issue 4, Oct - Dec 2012
VII. Simulation Results
After setting all these parameters, our ZigBee network model is
ready for the simulation. The simulation results concerning the
Throughput, End to End Delay, No. of Hops, Load per PAN,
across the full ZigBee stack, under different topology-deployment
strategies with variable Backoff Exponents, are analysed.
A. Throughput
Throughput is the ratio of the total amount of data that a receiver
receives from a sender to a time it takes for receiver to get the
last packet. Throughput is the data quantity transmitted correctly
starting from the source to the destination within a specified
time (seconds). A low delay in the network translates into higher
throughput. Throughput is quantified with varied factors including
packet collisions, obstructions between nodes and the type of
used topology.
Fig. 7: Star Topology Scenario
Fig. 10: Average Throughputs of Star, Tree and Mesh Topology.
The above result shows the maximum throughput achieves in tree
topology as compare to mesh and star.
Fig. 8: Mesh Topology Scenario
Fig. 9: Tree Topology Scenario
w w w. i j c s t. c o m
B. End-to End Delay
End-to-end delay refers to the time taken for a packet to be
transmitted across a network from source to destination.
dend-end = N[ dtrans+dprop + dproc]
where
dend-end = end-to-end delay
dtrans = transmission delay
dprop= propagation delay
dproc= processing delay
N= number of links (Number of routers + 1). Each router will
have its own dtrans, dprop, dproc hence this formula gives a rough
estimate.
Fig. 11: Average End to End Delay in Star, Mesh and Tree
Topologies
International Journal of Computer Science And Technology 709
IJCST Vol. 3, Issue 4, Oct - Dec 2012
Result shows in fig. 11, concludes that Mesh topology has maximum
value of end to end delay whereas star topology has minimum
end to end delay. This is due to more number of hops travel,
information takes extra time in order to reach to its destination in
mesh topologies and tree topologies as compare to star.
C. Number of Hops
It is the average number of hops traveled by application traffic
in the PAN. In the below figure star has single number of hop
whereas in case of mesh and tree it is double.
Fig. 12: Average No. of Hops in Star, Mesh and Tree
Topologies
D. Network Load
Represents the total load (in bits/sec) submitted to 802.15.4 MAC
by all higher layers in all WPAN nodes of the network. Here we
conclude that tree topology has the maximum networking load as
compare to mesh and star topologies, this is because more number
of hops travel by the data packets in case of tree topology rather
than star and mesh.
Fig. 13: Network Load in Star, Tree and Mesh Topologies
VIII. Conclusion
In this paper we have analysed the ZigBee/IEEE 802.15.4 standard
using three possible topologies in ZigBee WSN Networks. In this
work we provided a versatile analysis of the characteristics of the
710
International Journal of Computer Science And Technology
ISSN : 0976-8491 (Online) | ISSN : 2229-4333 (Print)
IEEE 802.15.4 topology formation process and the significant
impact on the overall network performance using different
parameters like throughput, MAC Delay, No. of Hops, Network
Load etc. The results show that tree topology outperforms among all
other topologies. We performed an extensive simulation analysis,
combined with a topological variation parameters related ZigBee
wireless sensor networks i.e. WPANs. This analysis is usable
to configure IEEE 802.15.4/ZigBee procedures and in selecting
the related parameters of ZigBee PAN Network. Overall, the
performance evaluations show that the ZigBee can only be use
for low-data rate and low-power smart grid applications not having
very high reliability requirements and real-time deadlines.
References
[1] Yu-Kai Huang et al.,“A Comprehensive Analysis of LowPower Operation for Beacon-Enabled IEEE 802.15.4 Wireless
Networks”, IEEE Transaction on Wireless Communications,
Vol. 8, No. 11, Nov. 2009.
[2] Lovish Jaiswal et al.,“ Performance analysis of backoff
exponent behaviour at MAC layer in ZigBee Sensor
Networks”, International Journal of Computer Applications,
Vol. 57, No. 22, November 2012.
[3] Chiara Buratti et al.,“Performance Analysis of IEEE 802.15.4
Beacon-Enabled Mode”, IEEE Transaction On Vehicular
Technology, Vol. 59, No. 4, May 2010.
[4] A. Cunha, M. Alves, A. Koubaa (2010),"Implementation
of the ZigBee Network Layer with Cluster-tree Support",
[Online] Available: http://www.openzb.net/research.php
[5] P. Jurcik, A. Koubaa, M. Alves, E. Tovar Z. Hanzalek, “A
Simulation Model for the IEEE 802.15.4 protocol: Delay/
Throughput Evaluation of GTS Mechanism”, in 15th Annual
Meeting of the IEEE International Symposium on Modeling,
Analysis and Simulation of Computer and Telecommunication
Systems (MASCOTS ‘07), Istanbul, Turkey, 2007, pp. 2426.
[6] Akyildiz, I. F., Su, Sankarasubramaniam, W. Y., Cayirci,
E.,“Wireless sensor networks: A survey”, Computer Networks
(Elsevier), Vol. 38, pp. 393-422, 2002.
[7] Pottie, G. J., Kaiser, W. J.,“Wireless Integrated Network
Sensors”, Communications of the ACM, Vol. 43, No. 5, pp.
551–558, May 2000.
[8] Al-Karaki, J. N., Kamal, A. E.,“Routing techniques in Wireless
Sensor Networks: A survey”, Department of Electrical and
Computer Engineering Iowa State University, Ames, Iowa
50011.
[9] Bluetooth SIG,“Bluetooth Specification v1.1”, 2001, [Online]
Available: http://www.bluetooth.org/spec/, Last accessed on
15 July 2011.
[10]Paolo Baronti et al.,“Wireless sensor networks: A survey on
the state of the art and the 802.15.4 and ZigBee standards”,
Computer Communications 30, 2007, pp. 1655–1695.
[11] Yu-Kai Huang et al.,“Distributed Throughput Optimization
for ZigBee Cluster-Tree Network”, IEEE Transaction On
Parallel and Distributed Systems, Vol. 23, No. 3, March
2012
[12]Chong, C., Kumar, P.,“Sensor s Networks: Evolution,
Opportunities, and Challenges”, Proceedings of the IEEE,
Vol.91, No. 8, August 2003.
[13]B.E. Bilgin, V.C. Gungor,“Performance evaluations of
ZigBee in different smart grid environments”, Computer
Networks 56, 2012, pp. 2196–2205.
w w w. i j c s t. c o m
ISSN : 0976-8491 (Online) | ISSN : 2229-4333 (Print)
[14]Kumar, H., Sarma, D., Kar, A., Mall, R.,“Energy Efficient
Communication Protocol for a Mobile Wireless Sensor
Network System”, in International Journal of Computer
Science and Network Security, Vol. 9, No. 2, February
2009.
[15]Zdenˇek Hanzálek, et al.,“Energy Efficient Scheduling for
Cluster-TreeWireless Sensor Networks With Time-Bounded
Data Flows: Application to IEEE 802.15.4/ZigBee”, IEEE
Transaction On Industrial Informatics, Vol. 6, No. 3, August
2010.
[16]Chia-Hung Tsai et al.,“ A Path-connected-cluster wireless
sensor network and its formation, addressing and routing
protocols”, IEEE Sensors Journal, Vol. 12, No. 6, june
2012.
[17]Shafiullah Khan et al.,“ Secure route selection in wireless
mesh network” Computer Networks 56, 2012, pp. 491–
503
[18]Chonggang Wang and Kazem Sohraby et al.,“Voice
Communications over ZigBee Networks”, Advances in
wireless Voip, AT&T Labs Research.
[19]Francesca Cuomo et al.,“Performance analysis of IEEE
802.15.4 wireless sensor networks: An insight into the
topology formation process”, Computer Networks 53, 2009,
pp. 3057–3075.
[20]Shizhong Chen et al.,“Analysis of the Power Consumption
for Wireless Sensor Network Node Based on ZigBee”, 2012
International Workshop on Information and Electronics
Engineering (IWIEE), Procedia Engineering 29, 2012, pp.
1994 – 1998
[21]Benoît Latre et al.,“Throughput and Delay Analysis of
Unslotted IEEE 802.15.4”, Journal of networks, Vol. 1, No.
1, May 2006.
w w w. i j c s t. c o m
IJCST Vol. 3, Issue 4, Oct - Dec 2012
Lovish Jaiswal honored his B-Tech degree
at Kurukshetra University, Kurukshetra
in 2010. He is currently a Full time
M-Tech Scholar in Electronics and
Comm. Engineering Dep’t at Shaheed
Bhagat Singh State Technical Campus,
Ferozepur, Punjab, INDIA. His research
mainly focuses on Wireless Network
Architecture, Security threats, Wireless
Communication Systems, Mobile Ad-hoc
and Sensor Networks.
Jaswinder Kaur received her B-Tech degree
in Electronics & Comm. Engineering
from Beant College of Engineering &
Tech., Gurdaspur, Punjab, India in 2002
and the M-Tech degree in Electronics &
Communication Engineering from Beant
College of Engineering & Technology,
Gurdaspur, Punjab, INDIA, in 2006.
Currently she is working as an Assistant
Professor at Shaheed Bhagat Singh State
Technical Campus, Ferozepur, Punjab, India. Her research
interests include Networking, Image Processing and Optical
Communication.
Gurjeevan Singh was born in Punjab, INDIA
in 1985. He has done his B-Tech. & M-Tech.
from P.T.U. Jalandhar. He has published
various research papers in internationals
journals. Presently, he is working as a
Department In-charge Electronics and
Communication Engineering at Shaheed
Bhagat Singh State Technical Campus
(Poly Wing), Ferozepur. His main Research
interests are Mobile Adhoc Networks,
Network Security, Sensor Networks and VLSI.
International Journal of Computer Science And Technology 711