Qos in wlan
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The document discusses quality of service (QoS) in wireless local area networks (WLANs). It describes the 802.11 medium access control schemes, including distributed coordination function (DCF) and point coordination function (PCF), and their limitations in providing QoS. It then introduces the 802.11e standard, which includes enhanced distributed channel access (EDCA) and HCF controlled channel access (HCCA) to provide QoS support and service differentiation for real-time applications like voice and video.
Qos in wlan
- 1. QoS In WLAN BY WAQAS SHEHZAD FAST NU PAKISTAN
- 2. Outline Introduction QoS Parameters. 802.11 medium access control schemes (MAC). 802.11e medium access control schemes (MAC). Conclusion. Reference.
- 3. Introduction What is 802.11? 802.11 refers to a family of specifications developed by the IEEE for wireless LAN technology. 802.11 Standards. 1997 - 802.11 up to 2Mbps (900MHZ). 1999 - 802.11b 2.4GHZ and up to 11Mbps. 1999 – 802.11a 5GHZ and up to 54Mbps. 200x – 802.11g 2.4GHZ and up to 54Mbps. 200x – 802.11e for QoS.
- 4. Quality of Service (QoS) QoS is the capability to provide resource assurance in a network. QoS Parameters: Bandwidth. Delay.(how long it takes for a bit of data to travel across the network from one node or endpoint to another.) Packet loss rate. Jitter.
- 5. QoS in TP link wireless router upload stream Download
- 6. IEEE 802.11e HCF Controlled Channel Access Enhanced DCF Channel Access
- 7. 802.11 medium access control schemes (MAC). There are two basic medium access control (MAC) modes: Distributed Coordination Function (DCF). Point Coordination Function (PCF).
- 8. Distributed Coordination Function (DCF) Contention-Based. Based on Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) algorithm. Designed for a best-effort service. Supports Asynchronous transmission.
- 9. Limitation of Distributed Coordination Function (DCF) Does not provide any QoS guarantees. Does not support real-time application. Designed for equal priorities. Does not support the concept of differentiating frames with different user priorities.
- 10. Point Coordination Function (PCF) Contention free-based. Uses a centralized polling scheme. Differentiation Considered based on priority. Supports synchronous transmission. .
- 11. Limitation of Point Coordination Function (PCF) poor QoS performance. Uses a simple round-robin algorithm, which can not handle the various QoS requirements. Transmission time of the polled stations is unknown.
- 12. Hybrid Coordination Function (HCF) There are two methods of channel access: Enhanced DCF channel access (EDCA). HCF controlled channel access (HCCA).
- 13. Enhanced DCF Channel Access (EDCA) Contention-Based channel access(many users to use the same radio channel without pre-coordination). Provides service differentiation. Classifies the traffic into 8 different classes. Each station has 4 access categories to provide service differentiation.
- 14. EDCA Priority Access Designation Category (AC) (Informative) 0 0 Best Effort 1 0 Best Effort 2 0 Best Effort 3 1 Video Probe 4 2 Video 5 2 Video 6 3 Voice 7 3 Voice
- 15. HCF Controlled Channel Access ( HCCA) Provides Guaranteed Services with a much higher probability than EDCA. Combines the advantages of PCF and DCF. Coordinates the traffic in any fashion (not just round- robin).
- 16. Conclusion The IEEE 802.11 wireless LAN (WLAN) has become one of the most widely used wireless technologies in these days. The 802.11 standards can not provide any QoS guarantees due to poor performance. The 802.11e offers QoS support to time- sensitive applications, such as, audio and video communications.