| Résumé : |
Description
ZigBee [1] is a network and application layer specification based
on the IEEE 802.15.4 standard [2] for Low-Rate Wireless Personal Area
Networks (LR-WPANs). ZigBee is developed by a multi-vendor consortium called
the ZigBee Alliance. Backed by more than 150 member companies, the ZigBee
standard was ratified in late 2004, and released for public non-commercial
use in June 2005. Eventhought this standard was not specifically developed
for Wireless Sensor Networks [3] (WSNs), it is intended to be suitable for
them since WSNs can be built up from LR-WPANs [4].
Routing strategy in ZigBee uses a combination of two kinds of routing
protocols as default. The first is a reactive routing protocol that
discovers the best route by broadcasting a route request and waiting for
replies from the destination or intermediate nodes, similar to the AODV
protocol. It has the drawback of being greedy with respect to bandwidth and
energy consumption. The second is a Tree Routing protocol, which is an
extremely simple routing algorithm where a node only forwards packets to its
parent or child nodes along the logical tree. This tree is established and
maintained based on link quality estimation. Typically, a node performs a
channel scan to identify the potential parents and chooses the one that
provides the best child-parent link quality. Link quality estimation is
performed using LQI (Link Quality Indicator), a hardware-based metric that
is directly read from the radio transceiver.
Zigbee Tree Routing is a low-overhead protocol. It avoids flooding the
network with route request/update messages, which conserves bandwidth and
energy. It avoids also storing routing tables, whose update would be a
costly operation. Hence, Zigbee Tree Routing is most suitable for
energy-constrained WSNs. However, some recent studies, such as [5-8] argued
that Zigbee Tree Routing has the main drawback of resulting in increased
hop-counts leading to inefficient routing. This is totally reasonable since
the logical tree forming and maintenance do not take into account the
hop-count information. Another weakness of Zigbee Tree Routing would be the
use of LQI metric for establishing and maintaining the tree. Indeed, the
child node selects or updates its current parent based on the measure of the
LQI that estimates the quality of the parent-child link. Previous empirical
studies have shown that such metric does not provide accurate link quality
estimation [10,11]. Furthermore, in [12], MultihopLQI- a tree routing
protocol based on LQI - has been shown as inefficient mainly due to
inaccuracy of LQI in estimating link quality.
In this project, we aim to improve Zigbee Tree Routing performance by
integrating a new metric for parent selection that we call F-PQI: Fuzzy
Parent Quality Indicator [13]. This metric is inspired from [14] and
consists in combining five different properties using Fuzzy Logic to select
the most convenient parent. These properties include Energy indicator (Ei),
Depth (Dp) (i.e. hop-count), Children Number (CN), four-bit [18] link
quality estimator, and LQI.
References
[1] ZigBee Alliance,
“ZigBee Specification “, ZigBee Document 053474r05, Version 1.0 , December
14th, 2004
[2] IEEE 802.15.4
Standard,” Part 15.4: Wireless Medium Access Control (MAC) and Physical
Layer (PHY) specifications for Low-Rate Wireless Personal Area Networks (LR-PANs)”,
IEEE Standard for Information Technology, IEEE-SA Standards Board, 2003.
[3] I. F. Akyildiz, W.
Su, Y. Sankarasubramaniam and E. Cayirci, “Wireless sensor networks, a
survey”, Computer networks, Volume 38, Issue 4 , 15 March 2002, Pages
393-422
[4] A. V. Nieuwenhuyse,
A. Koubaa, M. Alves, “On the use of the ZigBee protocol for Wireless Sensor
Networks”, IPP-HURRAY Technical Report, HURRAY-TR-060603, Jun 2006
[5] Kim, T., Kim, D.,
Park, N., Yoo, S., Lopez, T.S.: Shortcut Tree Routing in ZigBee Networks,
In: 2nd International Symposium Wireless Pervasive Computing,
2007.
[6] Qiu,W., Cheng,Q.,
Skafidas, E,.: A Hybrid Routing Protocol for Wireless Sensor Network,
International Symposium on Communications and Information Technologies, pp.
1383-1388, 2007.
[7] M. Al-Harbawi, M. F.
A. Rasid, N. K. Noordin, Improved Tree Routing (ImpTR) Protocol for ZigBee
Network, International Journal of Computer Science and Network Security,
VOL.9 No.10, October 2009
[8] Qiu, W., Skafidas,
E., and Hao, P. 2009. Enhanced tree routing for wireless sensor networks. Ad
Hoc Netw. 7, 3 (May. 2009), 638-650.
[9] Nefzi, B., Song, Y.:
Performance Analysis and Improvement of ZigBee Routing Protocol, 7th IFAC
International Conference on Fieldbuses & Networks in Industrial & Embedded
Systems, Toulouse, 2007.
[10] K. Srinivasan and P.
Levis, “Rssi is under appreciated,” in In Proceedings of the Third Workshop
on Embedded Networked Sensors, 2006.
[11] J. Polastre, R.
Szewczyk, and D. Culler, “Telos: enabling ultra-low power wireless research,”
in IPSN ’05: Proceedings of the 4th international symposium on Information
processing in sensor networks. Piscataway, NJ, USA: IEEE Press, 2005.
[12] Gnawali, O.,
Fonseca, R., Jamieson, K., Moss, D., and Levis. Collection tree protocol. In
Proceedings of the 7th ACM Conference on Embedded Networked Sensor Systems (SenSys
'09). ACM, New York, NY, 1-14. 2009
[13] Nouha Baccour, Anis
Koubaa, and Habib Youssef: Fuzzy Parent Quality Indicator (PQI): a new
metric for potential parents evaluation using Fuzzy logic, Work in progress.
[14] Nouha Baccour, Anis
Koubâa, Habib Youssef, Maissa Ben Jamâa, Denis do Rosario, Mario Alves and
Leandro Becker. F-LQE: A Fuzzy Link Quality Estimator for Wireless Sensor
Networks, The 7th European Conference on Wireless Sensor Networks (EWSN
2010), Coimbra, Portugal, September 17-19, 2010.
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