1. 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. 2 Presentation Outline 1. Overview of the WiMAX technology 2. WiMAX simulators 3. WiMAX Module for ns-3 Key challenges Key challenges Software design Software design –MAC Layer –PHY Layer 4. Limitations and future work 5. Conclusion

3. 3 Overview of WiMAX Technology

4. 4 Overview of WiMAX WiMAX (Worldwide Interoperability for Microwave Access ) is: A radio interface technology standardized by IEEE 8 02.16-2004 (802.16d) for fixed deployment[1] 8 02.16-2005 (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. 5 WiMAX on Simulators

6. 6 WiMAX simulators FeaturesWINSE(ns-2) Numbat (OMNET++) NCTUns PMPXXX Mesh--X OFDMXXX OFDMAXX- ARQXX- Initial Ranging XXX Service Flows management -XX Management connection XXX UGS SF XX- rtPS & nrtPS service flows X-- BE SF XXX ertPS SF X-- CS Packet Classifier X-X

7. 7 WiMAX Module for ns-3

8. 8 First WiMAX module for ns-3 Based on 802.16d and 802.16e standard The code is available at the following URL: http://code.nsnam.org/iamine/ns-3-wimax under the GNU License and has been recently merged with the main ns-3 dev treehttp://code.nsnam.org/iamine/ns-3-wimax 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. 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. 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. 11 Module Architecture

12. 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. 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. 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. 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. 16 Implementation: Things to be done... FeaturesWINSENumbatNCTUnsNS-3-WiMAX PMPXXXX Mesh--X- OFDMXXXX OFDMAXX-- ARQXX-- Initial Ranging XXXX Service Flows Initialization -XXX Management connection XXXX UGS class XX-X rtPS & nrtPs class X--X BE class XXXX ertPS class X--- CS Packet Classifier X--X

17. 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. 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.orgwww.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 1 st 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 18 th 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/. http://itpp.sourceforge.net/

19. 19 Thank you