WMEWME

802.11 ABC’s802.11 ABC’s

LayerLayer DescriptionDescription

aa PHYPHY 54 Mb/s in 5 GHz bands54 Mb/s in 5 GHz bands

bb PHYPHY 11 Mb/s direct sequence in 2.4 GHz band11 Mb/s direct sequence in 2.4 GHz band

cc MACMAC Bridging operationBridging operation

dd PHYPHY International domainsInternational domains

ee MACMAC Quality of service (QoS) (late ’04)Quality of service (QoS) (late ’04)

ff bothboth Access point interoperabilityAccess point interoperability

gg PHYPHY 54 Mb/s at 2.4 GHz (802.11b compatible)54 Mb/s at 2.4 GHz (802.11b compatible)

hh bothboth Coordination with European HiperLAN2 Coordination with European HiperLAN2 standardsstandards

ii MACMAC Security (mid ’04)Security (mid ’04)

2004

QoS/WME

WPA

802.11i/WPA2

802.11i802.11e

Wi-Fi Certifications

IEEE Standardization

QoS/WSM

20052003

Technology RoadmapTechnology Roadmap

QoS Considerations for QoS Considerations for VoiceVoice

Admission Control is requiredAdmission Control is required Streaming applications need priority Streaming applications need priority

serviceservice Bandwidth management required to Bandwidth management required to

maximize capacity and minimize maximize capacity and minimize contentioncontention

Battery life must be maximizedBattery life must be maximized Traffic is predictableTraffic is predictable Schedule periods of “sleep” are possibleSchedule periods of “sleep” are possible

IEEE 802.11eIEEE 802.11e

New medium access mechanism– Hybrid coordination function (HCF)

Priority classesPriority classes Enhanced Distributed Coordination Access (EDCA)Enhanced Distributed Coordination Access (EDCA)

Polled accessPolled access HCF Coordinated Channel Access (HCCA)HCF Coordinated Channel Access (HCCA)

Automatic Power Save Delivery (APSD)Automatic Power Save Delivery (APSD) APSD requires the Access Point to maintain a schedule APSD requires the Access Point to maintain a schedule

for the intervals it will send packetsfor the intervals it will send packets This allows device to predict when traffic will arrive This allows device to predict when traffic will arrive

and schedule periods of ‘sleep’ and schedule periods of ‘sleep’

Wi-Fi Alliance QoS Wi-Fi Alliance QoS ActivitiesActivities

Defined by the Wi-Fi Alliance, optional for Defined by the Wi-Fi Alliance, optional for Wi-Fi certificationWi-Fi certification

Two profilesTwo profiles Wi-Fi [Wireless] Multimedia Extensions (WMWi-Fi [Wireless] Multimedia Extensions (WM

E)E) Based on EDCA priority serviceBased on EDCA priority service

Wi-Fi [Wireless] Scheduled Multimedia (WSWi-Fi [Wireless] Scheduled Multimedia (WSM)M) Based on HCCA polled access, includes EDCABased on HCCA polled access, includes EDCA

WME vs. WSMWME vs. WSM

WMEWME WSMWSM

Based on 802.11eBased on 802.11e Based on 802.11e, includes Based on 802.11e, includes WMEWME

Based on EDCA (Enhanced Based on EDCA (Enhanced Distributed Coordination Distributed Coordination Access)Access)

Based on HCCA (HCF Based on HCCA (HCF Coordinated Channel Coordinated Channel Access)Access)

EDCA provides priority EDCA provides priority classes of serviceclasses of service

HCCA ‘reserves’ bandwidth HCCA ‘reserves’ bandwidth based on traffic based on traffic specifications from client specifications from client devicesdevices

Best suited for one way Best suited for one way audio applicationsaudio applications

Best suited for two way Best suited for two way streaming media (voice, streaming media (voice, video)video)

Triggered APSD OptionalTriggered APSD Optional Uses Scheduled APSD- Uses Scheduled APSD- suitable for power savesuitable for power save

A Hybrid ApproachA Hybrid Approach

Enhanced distributed channel access (EDCA)

Enhancement for 802.11 Distributed Coordination Function EDCA supports 8 priority values (traffic classes) Priority values (0 to 7) identical to the IEEE 802.1D priorities It does not guarantee that low priority frames will always wait

until all higher priority frames are transmitted Provides statistical traffic class differentiation

Mapping between 802.1D priorities and EDCA access categories.

Background

Spare

Best Effort

Excellent EffortControlled Load

Video

Voice

Network Control

HCF Controlled Channel Access (HCCA)

QoS-aware centralized coordinator (Hybrid Coordinator HC)

▪ Has higher priority than EDCA ▪ Polls terminals ▪ Provides o Negotiated connections between an access

point and terminals o Specifically assigned transmit times for eve

ry frame Close to strict QoS guarantees => Support for Voice over wireless LAN

WME 802.11 access WME 802.11 access pointpoint

SummarySummary Wireless LAN (WLAN) and Voice over IWireless LAN (WLAN) and Voice over I

P (VoIP) are no longer considered emeP (VoIP) are no longer considered emerging technologies. rging technologies.

All we have to do is reference the WLAAll we have to do is reference the WLAN phones that offer voice services to uN phones that offer voice services to understand that wireless IP phones are nderstand that wireless IP phones are now as real as wired IP phones. now as real as wired IP phones.