WME Overview 7/20/03 Thomas Kuehnel, et. al.
WME Motivation • Avoid multiple proprietary solutions (prevent market fragmentation) • Implementation guidelines • Early deployment of QoS • A subset of 802.11e • Direct migration path to 802.11e • Addresses letter ballot comments Thomas Kuehnel, et. al.
Letter Ballot Comments • EDCF Post-backoff: 267 • Explicit Admission Control/TSPEC: 184 • QoS Parameter Set Element: 1101 • AC mapping: 1686 • Distributed Admission Control Offers an alternative for 164 Thomas Kuehnel, et. al.
Scope • EDCF with four ACs and four queues • Adjust default parameters • Create a “background” category in line with 802.1D • Admission control for selected ACs • Centralized mechanism (in AP) • Prevents overload of queues • 802.11e signaling using TSPECs Thomas Kuehnel, et. al.
EDCF Test Environment STA 1 • 802.11a • PHY rate 36/54 Mbps • Multiple Vendor AP/STA STA 2 AP STA 3 STA 4 • Uplink RTP Traffic ( SDTV 6 Mbps) • Priority Equal • WiFi Test Suite STA 5 STA 6 Thomas Kuehnel, et. al.
Without Admission Control there is no QoS Pair 4 Starts Streaming Thomas Kuehnel, et. al.
Without Admission Control there is no QoS Thomas Kuehnel, et. al.
EDCA and Admission Control provides QoS Video Priority (AC default) Best Effort (default) Video Priority (AC default) Thomas Kuehnel, et. al.
Summary of Proposed Changes • Reduced Size of QoS Parameters Element in Beacon to increase efficiency • 44 Octets become 18 Octets (1 Octets) • Add flags to QoS Parameters Element to indicate which ACs require admission control • Changes to TSPEC element • Add contention-access bit to TSinfo field • Add new Medium Time field for response • New mapping of priorities to ACs in accordance with 802.1D • Bug fixes in EDCF post-backoff • Normative text in in 11-3-412R1-E-Proposed-Normative-Text_for_EDCA.doc Thomas Kuehnel, et. al.