TKN - Telecommunication Networks Group ... - of TKN - TU Berlin

TKN - Telecommunication Networks Group - Prof. Wolisz
An IEEE 802.11e EDCA and CFB Simulation Model for ns-2
Overview
Sven Wiethölter, Christian Hoene
The IEEE 802.11 standard supports two MAC mechanisms, the Distributed Coordination Function
(DCF) and the Point Coordination Function (PCF). These mechanisms are considered to be
insufficient for achieving a reasonable quality in scenarios with high background load. Thus, QoS
enhancements are vividly studied and evaluated. The QoS enhancements developed by the IEEE
802.11e WG have been under design for several years. The amendment to the 802.11 standard was
finally approved and published in November 2005. Basically, IEEE 802.11e introduces two additional
MAC modes: the Enhanced Distributed Channel Access (EDCA) and the HCF Controlled Channel
Access (HCCA), which have been derived from their earlier versions EDCF (Enhanced Distributed
Channel Function) and HCF (Hybrid Coordination Function) of previous drafts.
On this web page, we present an open-source, verified simulation model of IEEE 802.11e's EDCF /
EDCA mode for the network simulator (ns-2.26 / ns-2.28). We verified the model by comparing it with
previous results, which have been published by Stefan Mangold et al. The 802.11e EDCA model is
an easy adaptable, modular and documented solution. We added the contention free bursting (CFB)
to our model, which allows the transmission of a train of small packets without intermediate
contention. Sometimes CFB is also denoted as TXOP bursting.
Our simulation model is based on the ns-802.11 DCF model. Actually, it extends the wireless and
mobility code, which has been developed in the CMU Monarch project. We removed a couple of
bugs in the legacy model and expanded the queues as well as the MAC with its timer model into a
multi-dimensional MAC. The bug description, a short introduction into the model implementation and
its verification can be found here. Additionally, we provide a patch for the legacy 802.11 model of ns-
2.28 that can be downloaded here. It includes all fixes to the bugs described in the technical report
(TKN-03-019).
The EDCA model lacks the HCCA, the block ACK mechanism, any management mechanisms like
Association/Reassociation, Authentication/Deauthentication. In addition, no superframe structure
with Beacon frames and no power-saving methods are supported.
The RTS/CTS mechanism, which is included in the legacy ns-802.11 model, has never been tested
and verified. Therefore we do not recommend to use RTS/CTS without reviewing the code in detail.
We recommend to use the EDCA model for ns-2.28, since the older version is not compliant to the
final 802.11e amendment. An installation instruction is included in the readme file.
Download
● Sourceforge project web page for EDCA model (includes CVS, bug reports and support)
● Patch for 802.11 model (ns-2.28)
Publications
http://www.tkn.tu-berlin.de/research/802.11e_ns2/ (1 von 3)08.08.2011 17:50:04 Uhr
❍ Technical Report TKN-03-019, Sven Wiethölter, Christian Hoene, "Design and
Verification of an IEEE 802.11e EDCF Simulation Model in ns-2.26",
Telecommunication Networks Group, Technische Universität Berlin, November 2003.
(PDF)

TKN - Telecommunication Networks Group - Prof. Wolisz
http://www.tkn.tu-berlin.de/research/802.11e_ns2/ (2 von 3)08.08.2011 17:50:04 Uhr
❍ Technical Report TKN-04-11, Sven Wiethölter, Christian Hoene, Adam Wolisz,
"Perceptual Quality of Internet Telephony over IEEE 802.11e Supporting Enhanced
DCF and Contention Free Bursting", Telecommunication Networks Group, Technische
Universität Berlin, September 2004. (PDF)
❍ Technical Report TKN-06-003, Sven Wiethölter, M. Emmelmann, Christian Hoene,
Adam Wolisz "TKN EDCA Model for ns-2", Telecommunication Networks Group,
Technische Universität Berlin, June 2006. (PDF)
Publications refering to this model
❍ Alessandro Andreadis, Giuliano Benelli, and Riccardo Zambon, „Evaluation of QoS
Support for Multimedia Traffics in IEEE 802.11e “, in Proc. of SoftCOM, Split-Dubrovnik,
Croatia, September 2006.
❍ M. Thottan and M. C. Weigle, „Impact of 802.11e EDCA on Mixed TCP-based
Applications“, in Proc. of the International Wireless Internet Conference (WICON),
Boston, August 2006.
❍ A. Banchs and L. Vollero, „Throughput analysis and optimal configuration of 802.11e
EDCA“, Computer Networks, Volume 50, Issue 11, pp. 1749-1768, August 2006.
❍ Yi-Wen Lan, Jui-Hung Yeh, Jyh-Cheng Chen, and Zi-Tsan Chou, „Performance
Enhancement of IEEE 802.11e EDCA by Contention Adaption“, VTC 2005-Spring,
Stockholm, Sweden.
❍ C. Bettstetter, C. Prehofer, and A. Wolisz, "A Performance Comparison of QoS
Approaches for Ad Hoc Networks: 802.11e versus Distributed Resource Allocation", In
Proc. of European Wireless 2005, Nicosia, Cyprus, April 2005.
❍ Carlos Calafate, Pietro Manzoni, Manuel Malumbres, "Supporting soft real-time services
in MANETs using distributed admission control and IEEE 802.11e technology", 10th
IEEE Symposium on Computers and Communications (ISCC 2005), June 27-30, 2005,
La Manga del Mar Menor, Cartagena, Spain.
❍ Carlos T. Calafate, Pietro Manzoni, Manuel P. Malumbres. "On the Interaction Between
IEEE 802.11e and Routing Protocols in Mobile Ad-Hoc Networks," 13th Euromicro
Conference on Parallel, Distributed and Network-Based Processing (PDP'05), pp. 110-
117, 2005.
❍ L. Scalia, I. Tinnirello, “Differentiation mechanisms for heterogeneous traffic integration
in IEEE 802.11 networks," BroadWin 2004, October 2004, San Jose, USA.
❍ Carlos T. Calafate, M. P. Malumbres, Pietro Manzoni, "Assessing the effectiveness of
IEEE 802.11e in multi-hop network environments", 12th Annual Meeting of the IEEE /
ACM International Symposium on Modeling, Analysis, and Simulation of Computer and
Telecommunication Systems (MASCOTS), October 5-7 2004, Volendam The
Netherlands.
❍ Douglas J. Leith, Peter Clifford: Using the 802.11e EDCF to Achieve TCP Upload
Fairness over WLAN Links. WiOpt 2005: 109-118
❍ Ken Duffy, David Malone and Douglas J. Leith, „Modeling the 802.11 distributed
coordination function in non-saturated conditions,“ to appear IEEE Communications

TKN - Telecommunication Networks Group - Prof. Wolisz
Letters (2005).
❍ Lu Yang, “P-HCCA: A New Scheme for Real-time Traffic with QoS in IEEE 802.11e
Based Networks,” APAN Network Research Workshop 2004 .
❍ Andrea Alfieri, „Simulazione del modello Enhanced Distributed Coordination Function
(EDCF) tramite NS-2“, Thesis, UNIVERSITA’ DEGLI STUDI DI PARMA, Italy, 2005.
Contact
If you use our model, please send us a brief email with a reference to your publication.
If you have any questions please mail them to the sourceforge.net or the ns-2 mailing list. We
are sorry to announce that we are not going to answer any emails regarding 802.11e anymore.
❍ Sourceforge IEEE802.11e ns/2 mailing lists
❍ The ns/2 mailing lists
Related Links
http://www.tkn.tu-berlin.de/research/802.11e_ns2/ (3 von 3)08.08.2011 17:50:04 Uhr
❍ IEEE 802.11 Working Group
❍ IEEE 802.11e HCCA simulation using the Network Simulator 2 by the Computer
Networking Group of the University of Pisa
❍ Stanford's 802.11e implementation for ns/2
❍ Qiang Ni's EDCF/HCF implementations for ns/2
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