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WME

WME. 802.11 ABC ’ s. Technology Roadmap. IEEE Standardization. 802.11e. 802.11i. 2004. 2005. 2003. WPA. 802.11i/WPA2. QoS/WME. QoS/WSM. Wi-Fi Certifications. QoS Considerations for Voice. Admission Control is required Streaming applications need priority service

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WME

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  1. WME

  2. 802.11 ABC’s

  3. Technology Roadmap IEEE Standardization 802.11e 802.11i 2004 2005 2003 WPA 802.11i/WPA2 QoS/WME QoS/WSM Wi-Fi Certifications

  4. QoS Considerations for Voice • Admission Control is required • Streaming applications need priority service • Bandwidth management required to maximize capacity and minimize contention • Battery life must be maximized • Traffic is predictable • Schedule periods of “sleep” are possible

  5. IEEE 802.11e • New medium access mechanism– Hybrid coordination function (HCF) • Priority classes • Enhanced Distributed Coordination Access (EDCA) • Polled access • HCF Coordinated Channel Access (HCCA) • Automatic Power Save Delivery (APSD) • APSD requires the Access Point to maintain a schedule for the intervals it will send packets • This allows device to predict when traffic will arrive and schedule periods of ‘sleep’

  6. Wi-Fi Alliance QoS Activities Defined by the Wi-Fi Alliance, optional for Wi-Fi certification Two profiles • Wi-Fi [Wireless] Multimedia Extensions (WME) • Based on EDCA priority service • Wi-Fi [Wireless] Scheduled Multimedia (WSM) • Based on HCCA polled access, includes EDCA

  7. WME vs. WSM

  8. A Hybrid Approach

  9. 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.

  10. 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 every frame • Close to strict QoS guarantees => Support for Voice over wireless LAN

  11. WME 802.11 access point

  12. Summary • Wireless LAN (WLAN) and Voice over IP (VoIP) are no longer considered emerging technologies. • All we have to do is reference the WLAN phones that offer voice services to understand that wireless IP phones are now as real as wired IP phones.

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