802.11e - QoS for Wi-Fi =========================== .. toctree:: :maxdepth: 1 :hidden: :includehidden: 802_11e/802_11e 802_11e/mac_functions 802_11e/mac_timings 802_11e/packet_formats 802_11e/power_save 802_11e/interoperability 802_11e/physical_rates 802_11e/ppdu 802_11e/channels 802_11e/PHYs IEEE 802.11e is an amendment to the Wi-Fi standard that adds Quality of Service (QoS) features to support prioritized traffic for applications like voice, video, and streaming over wireless networks. .. list-table:: :widths: 20 60 20 :header-rows: 1 * - Category - Description - Use Case * - MAC Functions - Enhanced MAC layer functions including traffic prioritization and QoS control. - Managing prioritized wireless communication for time-sensitive data * - MAC Timings - Timing parameters for traffic differentiation including varying interframe spaces. - Enabling prioritized medium access and reduced latency for high-priority traffic * - Packet Formats - Frame formats extended to support QoS fields like Traffic Identifier (TID). - Differentiating and managing traffic classes at frame level * - Power Save - QoS-aware power saving mechanisms allowing buffered delivery of prioritized traffic. - Maintaining energy efficiency without compromising service quality * - Interoperability - Ensures backward compatibility with legacy 802.11 devices and standards. - Supporting mixed networks with QoS enhancements * - Physical Rates - Supports data rates similar to underlying PHY, with emphasis on QoS scheduling. - Efficient throughput management for multimedia applications * - PPDU - Frame formats supporting QoS control information within the physical data units. - Reliable synchronization and prioritized data transmission * - Channels - Frequency bands and channel assignments in 802.11e (inherits from 802.11a/b/g). - QoS-aware channel usage for prioritized traffic handling * - PHY Overview - Overview of the Physical Layer context for 802.11e, typically built on 802.11a/g PHY. - Supports time-sensitive applications (e.g., VoIP, video) through MAC-layer QoS enhancements .. tab-set:: .. tab-item:: 802.11e (QoS Enhancements) **Standard:** IEEE 802.11e (2005) **Main Features:** - Introduces Quality of Service (QoS) support for Wi-Fi networks - Defines Enhanced Distributed Channel Access (EDCA) for traffic prioritization - Implements Hybrid Coordination Function Controlled Channel Access (HCCA) - Adds traffic classes for voice, video, best effort, and background traffic - Enables priority-based media access for real-time applications - Compatible with existing 802.11 standards (a/b/g/n) **Use Cases:** - VoIP and video conferencing over Wi-Fi - Streaming real-time multimedia content - Enterprise-grade wireless networking with QoS policies - Prioritized Wi-Fi traffic in crowded environments **Related Concepts:** - EDCA and Access Categories (AC) - HCCA scheduler and polling - Traffic Specification (TSPEC) - Admission control in WLANs - QoS tagging (802.1p, DSCP) .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the QoS enhancements of 802.11e:** * :ref:`Learnings in this section <802_11e_step1>` * :ref:`Terminology <802_11e_step2>` * :ref:`Version Info <802_11e_step3>` * :ref:`802_11e Version&IEEE Details <802_11e_step4>` * :ref:`802_11e Basic Setup on Ubuntu using IPv4 <802_11e_step5>` * :ref:`802_11e Basic Setup on Ubuntu using IPv6 <802_11e_step6>` * :ref:`Reference links <802_11e_step16>` .. button-link:: ./802_11e/802_11e.html :color: primary :shadow: :expand: Jump to "802.11e Basics" .. tab-set:: .. tab-item:: 802.11e MAC Functions **Standard:** IEEE 802.11e (2005) **Main Features:** - Adds Quality of Service (QoS) features to the MAC layer for traffic prioritization - Implements Enhanced Distributed Channel Access (EDCA) for differentiated medium access - Manages traffic categories with varying priority levels using Traffic Identifiers (TIDs) - Controls frame exchanges with QoS-specific acknowledgments and retransmissions - Supports admission control and traffic shaping for multimedia applications - Works in conjunction with the physical layer to ensure timely and prioritized data delivery **Use Cases:** - Prioritizing voice, video, and streaming traffic in Wi-Fi networks - Supporting low-latency applications such as VoIP and online gaming - Managing network resources for mixed traffic types with QoS requirements **Related Functions:** - Traffic category mapping and scheduling - QoS parameter signaling and negotiation - Enhanced access mechanisms like EDCA and HCF (Hybrid Coordination Function) - Power save support with QoS considerations .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11e MAC Functions:** * :ref:`Reference links ` .. button-link:: ./802_11e/mac_functions.html :color: primary :shadow: :expand: Jump to "802.11e MAC Functions" .. tab-set:: .. tab-item:: 802.11e MAC Timings **Standard:** IEEE 802.11e (2005) **Main Features:** - Defines enhanced timing parameters to support Quality of Service (QoS) - Introduces Arbitration Interframe Space (AIFS) replacing DIFS for prioritized access - Specifies variable contention window sizes based on traffic categories - Includes Timing for Enhanced Distributed Channel Access (EDCA) and Hybrid Coordination Function (HCF) - Ensures fair and differentiated medium access among multiple traffic priorities - Manages retransmission timing with QoS-awareness to meet latency requirements **Use Cases:** - Prioritizing voice and video traffic in WLANs for reduced latency - Controlling access timing to meet service level agreements in enterprise Wi-Fi - Enhancing multimedia streaming quality with efficient channel access timing **Related Timing Parameters:** - Arbitration Interframe Space (AIFS) - Contention Window (CWmin, CWmax) per traffic category - Short Interframe Space (SIFS) - Enhanced Backoff and retransmission timing .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11e MAC Timings:** * :ref:`Reference links ` .. button-link:: ./802_11e/mac_timings.html :color: primary :shadow: :expand: Jump to "802.11e MAC Timings" .. tab-set:: .. tab-item:: 802.11e Packet Formats **Standard:** IEEE 802.11e (2005) **Main Features:** - Defines enhanced MAC and PHY layer frame structures supporting QoS - Includes Frame Control, Duration, Address fields, Sequence Control, and CRC - Supports data, management, and control frames with QoS tagging - Introduces Traffic Identifier (TID) fields to prioritize packets - Uses EDCA and HCCA-specific fields in frames for QoS scheduling - Allows fragmentation, reassembly, and retransmission with QoS awareness **Use Cases:** - Structuring wireless packets to support prioritized voice and video traffic - Ensuring timely delivery and acknowledgment of multimedia frames - Enhancing interoperability by standardized QoS-enabled frame formats **Related Frame Types:** - QoS data frames with TID field (e.g., voice, video, best effort) - Management frames (e.g., Beacon, Probe Request) - Control frames (e.g., ACK, RTS, CTS) .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11e Packet Formats:** * :ref:`Reference links ` .. button-link:: ./802_11e/packet_formats.html :color: primary :shadow: :expand: Jump to "802.11e Packet Formats" .. tab-set:: .. tab-item:: 802.11e Power Saving Mechanisms **Standard:** IEEE 802.11e (2005) **Main Features:** - Enhances Power Save Mode (PSM) with QoS awareness to optimize energy usage - Supports Automatic Power Save Delivery (APSD) for improved power efficiency - Allows stations to enter sleep states and wake for scheduled QoS data delivery - AP buffers frames and signals buffered traffic using TIM and DTIM in beacon frames - Supports both Scheduled APSD (S-APSD) and Unscheduled APSD (U-APSD) for different traffic types - Integrates power saving with QoS mechanisms to balance performance and battery life **Use Cases:** - Extending battery life in mobile devices with multimedia streaming - Efficient power management in VoIP and video-over-Wi-Fi applications - Reducing power consumption in QoS-sensitive wireless LAN environments **Related Mechanisms:** - APSD protocol for scheduled frame delivery - Beacon frame scheduling with TIM and DTIM fields - Client sleep/wake coordination integrated with QoS traffic priorities .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11e Power Saving mechanisms:** * :ref:`Reference links ` .. button-link:: ./802_11e/power_save.html :color: primary :shadow: :expand: Jump to "802.11e Power Saving" .. tab-set:: .. tab-item:: 802.11e Interoperability **Standard:** IEEE 802.11e (2005) **Main Features:** - Ensures compatibility between devices from different vendors supporting QoS enhancements - Maintains backward compatibility with legacy 802.11 standards (e.g., 802.11a/b/g) - Defines interoperable QoS signaling and management frames for seamless communication - Implements enhanced medium access coordination with QoS-aware EDCA and HCCA - Supports coexistence with non-QoS devices in mixed networks without interference - Standardizes management and control frame exchanges for QoS-capable devices **Use Cases:** - Deploying multi-vendor Wi-Fi networks with QoS support for voice and video - Enabling smooth handoff and roaming in QoS-aware wireless LAN environments - Operating mixed legacy and QoS-capable networks without performance degradation **Related Mechanisms:** - QoS management frame interoperability - EDCA and HCCA coexistence strategies - Standardized PHY and MAC layer QoS procedures .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11e Interoperability mechanisms:** * :ref:`Reference links ` .. button-link:: ./802_11e/interoperability.html :color: primary :shadow: :expand: Jump to "802.11e Interoperability" .. tab-set:: .. tab-item:: 802.11e Physical Rates **Standard:** IEEE 802.11e (2005) **Main Features:** - Builds upon the physical rates of underlying 802.11 standards (e.g., 802.11a/b/g) - Supports multiple data rates with QoS prioritization for traffic differentiation - Utilizes OFDM or DSSS modulation schemes depending on base standard - Enables dynamic rate adaptation based on link quality and traffic class - Uses standard channel widths of 20 MHz in 2.4 GHz and 5 GHz bands - Facilitates enhanced throughput for prioritized traffic such as voice and video **Use Cases:** - Delivering QoS-enabled wireless multimedia streaming and VoIP - Supporting differentiated traffic classes in enterprise WLANs - Enabling efficient bandwidth utilization for mixed traffic types **Related Concepts:** - Enhanced Distributed Channel Access (EDCA) rate adaptation - Modulation and coding schemes (MCS) - Traffic differentiation and prioritization .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11e Physical Rates:** * :ref:`physical_rates in 802.11e ` * :ref:`Reference links ` .. button-link:: ./802_11e/physical_rates.html :color: primary :shadow: :expand: Jump to "802.11e Physical Rates" .. tab-set:: .. tab-item:: 802.11e PPDU **Standard:** IEEE 802.11e (2005) **Main Features:** - Defines the Physical Protocol Data Unit (PPDU) structure building on base 802.11 standards - Includes preamble and header fields for synchronization and signaling - SIGNAL field indicates data rate, length, and QoS parameters - Payload carries MAC frames with QoS enhancements, encoded using OFDM or DSSS depending on base PHY - Supports multiple data rates with adaptive modulation and coding schemes - Enables reliable, QoS-aware wireless transmission in 2.4 GHz and 5 GHz bands **Use Cases:** - Transmitting QoS prioritized traffic such as voice and video over Wi-Fi - Ensuring synchronization and efficient data transmission with QoS support - Facilitating coexistence with legacy 802.11 devices while enhancing performance **Related Concepts:** - Enhanced Distributed Channel Access (EDCA) - Modulation and coding schemes (MCS) - Preamble types and frame aggregation .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11e PPDU:** * :ref:`Reference links ` .. button-link:: ./802_11e/ppdu.html :color: primary :shadow: :expand: Jump to "802.11e PPDU" .. tab-set:: .. tab-item:: 802.11e Channels **Standard:** IEEE 802.11e (2005) **Main Features:** - Extends IEEE 802.11a/b/g MAC with QoS enhancements for time-sensitive traffic - Inherits PHY layer characteristics from 802.11a (5 GHz) and 802.11b/g (2.4 GHz) - Uses same channel plans as 802.11a or 802.11g depending on the operating band - Introduces Enhanced Distributed Channel Access (EDCA) for prioritized access - Compatible with existing UNII and ISM bands, no new frequencies defined - Designed for improved multimedia performance and VoIP over Wi-Fi **Use Cases:** - Quality of Service (QoS) in wireless networks (voice/video prioritization) - Enterprise Wi-Fi supporting multimedia and real-time traffic - WLANs requiring traffic differentiation across access categories (ACs) **Related Concepts:** - EDCA (Enhanced Distributed Channel Access) - HCF (Hybrid Coordination Function) - Access Categories (Voice, Video, Best Effort, Background) - PHY-layer inheritance from 802.11a/b/g .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11e Channels:** * :ref:`List of channels ` * :ref:`List of channel widths ` * :ref:`List of Bands ` * :ref:`Reference links ` .. button-link:: ./802_11e/channels.html :color: primary :shadow: :expand: Jump to "802.11e Channels" .. tab-set:: .. tab-item:: 802.11e PHY **Standard:** IEEE 802.11e (2005) **Main Features:** - Enhances the MAC layer to provide Quality of Service (QoS) for wireless LANs - Introduces Enhanced Distributed Channel Access (EDCA) for prioritized traffic - Defines Hybrid Coordination Function (HCF) combining contention-based and controlled channel access - Supports traffic differentiation via Access Categories (Voice, Video, Best Effort, Background) - Inherits PHY layer characteristics from underlying standards (802.11a/b/g) - Enables improved performance for multimedia and real-time applications over Wi-Fi **Use Cases:** - Prioritizing voice and video traffic to reduce latency and jitter - Enhancing wireless performance in enterprise and multimedia-rich environments - Supporting real-time applications like VoIP and streaming video over Wi-Fi networks **Related Concepts:** - MAC layer QoS mechanisms: EDCA, HCF, TXOP (Transmission Opportunity) - Access Categories and Traffic Prioritization - PHY layer inherited from 802.11a/b/g standards - QoS parameter negotiation and traffic scheduling .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11e PHY and MAC enhancements:** * :ref:`Reference links ` .. button-link:: ./802_11e/PHYs.html :color: primary :shadow: :expand: Jump to "802.11e PHY"