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

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

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

IPS MoMe 2005, Warsaw, Poland, th March Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY Legacy 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

IPS MoMe 2005, Warsaw, Poland, th March Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY Legacy 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

IPS MoMe 2005, Warsaw, Poland, th March Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY e 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

IPS MoMe 2005, Warsaw, Poland, th March Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY e - 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

IPS MoMe 2005, Warsaw, Poland, th March Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY e – 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)

IPS MoMe 2005, Warsaw, Poland, th March Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY HCCA Scheduling  The e 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

IPS MoMe 2005, Warsaw, Poland, th March 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

IPS MoMe 2005, Warsaw, Poland, th March 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

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

IPS MoMe 2005, Warsaw, Poland, th March 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

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

IPS MoMe 2005, Warsaw, Poland, th March 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 e  QSTA scheduler: FIFO with only one TS

IPS MoMe 2005, Warsaw, Poland, th March 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)  11 Mbps  Error-free channel  No RTS/CTS, no MAC fragmentation

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

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

IPS MoMe 2005, Warsaw, Poland, th March Dipartimento di Ingegneria dell'Informazione – University of Pisa, ITALY Conclusions and future work  A software architecture for simulating the IEEE e 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 e

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