1. Claudio Cicconetti, Luciano Lenzini, Enzo Mingozzi, Giovanni Stea Dipartimento di Ingegneria dell'Informazione University of Pisa, Italy IPS-MoMe 2005 Warsaw, Poland, 14-15 th March 2005 A Software Architecture for Simulating IEEE 802.11e HCCA

2. IPS MoMe 2005, Warsaw, Poland, 14-15 th March 2005 2 Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY Summary  Introduction  Software Architecture  Implementation and preliminary results  Conclusions

3. IPS MoMe 2005, Warsaw, Poland, 14-15 th March 2005 3 Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY Introduction  New (EuQoS) applications require QoS vvideoconference vVoIP vonline gaming v...  The legacy IEEE 802.11 lacks QoS support vDistributed Coordination Function vPoint Coordinated Function  Solution: 802.11e vEnhanced Distributed Channel Access (prioritized access) vHCF Controlled Channel Access (parametrized access)

4. IPS MoMe 2005, Warsaw, Poland, 14-15 th March 2005 4 Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY Legacy 802.11 - DCF  Distributed protocol, based on CSMA/CA: vlisten before transmit vcollisions detected with positive acknowledgment vbinary exponential backoff procedure if collision  All the stations access the medium with the same procedure vOnly suitable for best-effort traffic

5. IPS MoMe 2005, Warsaw, Poland, 14-15 th March 2005 5 Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY Legacy 802.11 - PCF  Contention-Free Periods (CFPs) alternates to Contention-Periods (CPs) at fixed intervals  During CFPs the AP cyclically polls the STAs  Still unsuitable for providing QoS

6. IPS MoMe 2005, Warsaw, Poland, 14-15 th March 2005 6 Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY 802.11e Enhancements  QoS Access Point (QAP), with venhanced scheduling capabilities vAdmission control  QoS Stations (QSTAs), capable of vContention-based access  DCF, EDCA vResponding to polls  PCF, HCCA

7. IPS MoMe 2005, Warsaw, Poland, 14-15 th March 2005 7 Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY 802.11e - EDCA  Distributed protocol  Up to four Access Categories  Based on the differentiation of the CSMA/CA parameters  Achieves relative differentiation of traffic from different ACs  If in infrastructure mode, admission control at the QAP

8. IPS MoMe 2005, Warsaw, Poland, 14-15 th March 2005 8 Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY 802.11e – HCCA (i)  Centralized  Up to 8 Traffic Streams (TSs) for each QSTA  Traffic specs and requirements (TSPEC) negotiation vMean data rate, delay bound, etc.  Admission control of TSs at the QAP  Absolute QoS guarantees enforced by scheduling Controlled Access Phases (CAPs)

9. IPS MoMe 2005, Warsaw, Poland, 14-15 th March 2005 9 Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY HCCA Scheduling  The 802.11e does not define a standard scheduling algorithm at the QAP  A reference scheduler is provided vTDM-like scheduling: TXOP of fixed duration at fixed time intervals for all admitted TSs  Different schedulers are currently being proposed in the literature vWe need a common framework for evaluation and testing

10. IPS MoMe 2005, Warsaw, Poland, 14-15 th March 2005 10 Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY Software Architecture  Modular architecture vMAC fully compliant to the standard HCCA function vMAC functions separated from HCCA scheduling vAllows for flexible integration of various schedulers

11. IPS MoMe 2005, Warsaw, Poland, 14-15 th March 2005 11 Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY MAC (i)  CAP_Hand  Has_Control/Lost_Control  Transmit  Receive/Data_Receive  Success  MAC is implemented as a FSM driven by a set of events

12. IPS MoMe 2005, Warsaw, Poland, 14-15 th March 2005 12 Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY MAC (ii)

13. IPS MoMe 2005, Warsaw, Poland, 14-15 th March 2005 13 Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY HCCA Scheduler (i)  Listens to a subset of the MAC events  Has_Control/Lost_Control vPossibly others, depending on its actual needs  General interface:  enque(): adds a new packet coming from the LL  deque(): pops the HOL packet  QAP-specific functions  get_next_cap(): returns the expiration time of the next CAP  addTSPEC(): requests the admission of a new TS

14. IPS MoMe 2005, Warsaw, Poland, 14-15 th March 2005 14 Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY HCCA Scheduler (ii)

15. IPS MoMe 2005, Warsaw, Poland, 14-15 th March 2005 15 Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY Implementation  The software architecture was implemented in the Network Simulator 2 simulation environment  QAP scheduler: reference 802.11e  QSTA scheduler: FIFO with only one TS

16. IPS MoMe 2005, Warsaw, Poland, 14-15 th March 2005 16 Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY Preliminary Results (i)  1 QAP  3 QSTAs (bidirectional video streaming session)  3 legacy STAs (asymptotic condition)  802.11b @ 11 Mbps  Error-free channel  No RTS/CTS, no MAC fragmentation

17. IPS MoMe 2005, Warsaw, Poland, 14-15 th March 2005 17 Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY Preliminary Results (ii)

18. IPS MoMe 2005, Warsaw, Poland, 14-15 th March 2005 18 Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY Preliminary Results (iii)

19. IPS MoMe 2005, Warsaw, Poland, 14-15 th March 2005 19 Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY Conclusions and future work  A software architecture for simulating the IEEE 802.11e HCCA was defined  The scheduling and MAC functions were decoupled by a generic communication interface  The contributed framework has been implemented using ns2  Future (ongoing) work vDefining, implementing and comparing different HCCA scheduling algorithms for 802.11e

20. IPS MoMe 2005, Warsaw, Poland, 14-15 th March 2005 20 Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY End of presentation  Thanks for your attention  ?? || //