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An Improved WiMAX Module for ns-3 Simulator _____________________________

Mohamed Amine Ismail Amine.ismail@{UDcast.com,INRIA.fr} INRIA, Planete Team R&D Department UDcast. An Improved WiMAX Module for ns-3 Simulator _____________________________. 3rd International ICST Conference on Simulation Tools and Techniques SIMU Tools 2010 Workshop on NS-3

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An Improved WiMAX Module for ns-3 Simulator _____________________________

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  1. Mohamed Amine Ismail Amine.ismail@{UDcast.com,INRIA.fr} INRIA, Planete Team R&D Department UDcast An Improved WiMAX Module for ns-3 Simulator_____________________________ 3rd International ICST Conference on Simulation Tools and Techniques SIMUTools2010 Workshop on NS-3 Torremolinos, Malaga, Spain - March 15 2010

  2. Presentation Outline Overview of the WiMAX technology WiMAX simulators WiMAX Module for ns-3 Key challenges Software design MAC Layer PHY Layer Limitations and future work Conclusion

  3. Overview of WiMAX Technology

  4. Overview of WiMAX WiMAX (Worldwide Interoperability for Microwave Access ) is: • A radio interface technology standardized by IEEE • 802.16-2004 (802.16d) for fixed deployment[1] • 802.16-2005 (802.16e) for mobile deployment[2] • IEEE defines layer 1 (PHY) and layer 2(MAC) details. The scope is limited to the interface between terminals (SS) and Base Station (BS)‏ • An end-to-end architecture defined by the WiMAX Forum (WMF) [3] • The architecture details how to deploy 802.16 • A label for Compliance/Interoperability, delivered by WMF • WMF takes in charge the definition and realization of certification

  5. WiMAX on Simulators

  6. WiMAX simulators

  7. WiMAX Module for ns-3

  8. WiMAX Module for ns-3 • First WiMAX module for ns-3 • Based on 802.16d and802.16e standard • The code is available at the following URL: http://code.nsnam.org/iamine/ns-3-wimaxunder the GNU License and has been recently merged with the main ns-3 dev tree • Implements the Point-to-Multipoint (PMP) topology with TDD mode and MAN ODFM PHY • Supporting important features including QoS scheduling service, bandwidth management, uplink request/grant scheduling… • Built completely in C++ with more than 65 classes and approximately 30000 lines of code

  9. Key challenges • Understanding 802.16 • A complex technology, huge specification, vague description • Open Area (Scheduling, Burst adaptation)‏ • Programming challenges • Compliance with ns-3 API and coding standard • Time and memory efficient code • Robust architecture • Cross layer design • Parallel MAC and PHY development , interdependence MAC/PHY

  10. Software Design • Design fully object oriented • Class WimaxNetDevice for the MAC layer of WiMAX it extends the NetDevice class of ns-3 • WimaxNetDevice is extended by BaseStationNetDevice and SubscriberStationNetDevice defining the MAC layers of BS and SS respectively. • The key functions of MAC are distributed to several other classes like: LinkManager, UplinkScheduler, SsScheduler, BsScheduler, ConnectionManager, serviceFlowManager, BurstProfileManager, ...

  11. Module Architecture

  12. MAC Layer • The 802.16 MAC layer is divided in to two sublayers: The Convergence sublayer (CS) and the Common-part sublayer (CPS)‏ • CS is responsible for: • Receiving packets from the higher layer and from peer stations • Classifying packets to appropriate connections • Keeps a mapping between connection ID and service flows • CPS is responsible for • Framing and management messages (DL and UL MAP, packet burst, ... )‏ • Downlink and Uplink scheduling • three uplink schedulers • two downlink sechdulers • Network Entry and Initialization • Connection and addressing • Service flow creation (DSA-X messages) • Bandwidth request and Grant Mechanism

  13. PHY layer • The older version of module (2009) provided two different version of PHY layer • The first one is a basic implementation • Simply forwards bursts received by the MAC layer ignoring any underlying PHY layer details very simplistic and not realistic • The second is very complete and implements all the OFDM operation using IT++ library [8] • Hardly usable for scalability reasons

  14. PHY layer • New implementation of PHY layer • Based on WirelessMAN-OFDM specification • Implemented by the SimpleOfdmWiMAXPhy Class • Block encoding : packet burst are converted to bit stream and then splitted into smaller FEC blocks • Supports all the 7 modulations and coding schemes (MCS) • Uses pre-generated SNR to Block Error Rate trace files

  15. Implementation: Things already done... • Basic architecture, framing, base station, subscriber station, ... • Creation, transmission and processing of control messages • Scanning synchronization and network entry • Link management: Transmission of ranging messages • Dynamic creation of connections and service flows (DSX-messages) • New downlink and uplink schedulers • A scalable and realistic physical layer • Support for Multicast • IP packet Classifier enabling the support of multiple service flows per SS • Support of fragmentation and defragmentation of MAC PDUs

  16. Implementation: Things to be done...

  17. Conclusion • We have proposed a WiMAX module for ns-3 simulator • The module implements the key components of WiMAX MAC and PHY • Implementing the PMP mode with OFDM specifications • design fully object-oriented • High attention has been put to come up with a standard compliant implementation • Merged with the main branch of ns-3. Release 3.8 expected by end of April • We hope this module contributes to the scientific society and facilitates in evaluating and designing WiMAX systems.

  18. References • [1] IEEE std. 802.16-2004, IEEE Standard for Local and Metropolitan Area Networks- Part 16: Air Interface for fixed Broadband Wireless Access Systems. October 2004. • [2] IEEE std. 802.16e-2005, IEEE Standard for Local and Metropolitan Area Networks- Part 16: Air Interface for fixed Broadband Wireless Access Systems- Amendment 2: Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands. February 2006. • [3] www.wimaxforum.org • [4] J.Chen, C.-C Wnag, F.C.-D. Tsai, C.-W. Chang, S.-S. Liu, J. Guo, W.-j. Lien, I.-H Sum and C.-H Hung. Desing and Implementation of WiMAX Module for ns-2 Simulator. In 1st International Conference on Performance Evaluation Methodologies and Tool, October 2006 • [5] The Network Simulator ns-2 NIST add-on – IEEE 802.16 model (MAC+PHY). Technical report, National Institute of Standards and Technology, June 2007 • [6] J.F. Borina and N.L. Da Fonseca. WiMAX Module for ns-2 Simulator. In 18th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communication (PIMRC'07). IEEE, September 2007 • [7] F. Cristiani. Simulation of WiMAX Physical Layer. Technical report, Universita degli Studi di Napoli. Federico II, Italy, December 2007 • [8] IT++ Library of mathematical, signal processing and communication routines, http://itpp.sourceforge.net/.

  19. Thank you

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