802.11u - Interworking ========================= .. toctree:: :maxdepth: 1 :hidden: :includehidden: 802_11u/802_11u 802_11u/mac_functions 802_11u/mac_timings 802_11u/packet_formats 802_11u/power_save 802_11u/interoperability 802_11u/physical_rates 802_11u/ppdu 802_11u/channels 802_11u/PHYs IEEE 802.11u is an amendment that enhances interworking with external networks, enabling seamless access and roaming between Wi-Fi and cellular or other networks. .. list-table:: :widths: 20 60 20 :header-rows: 1 * - Category - Description - Use Case * - MAC Functions - Enhances MAC layer with support for extended service discovery, QoS, and network selection. - Facilitating network selection and access control in public Wi-Fi hotspots. * - MAC Timings - Uses standard 802.11 MAC timing mechanisms; coordinates with ANQP exchanges. - Timely management of authentication and access in multi-operator environments. * - Packet Formats - Includes new Information Elements (IEs) in management frames like beacon, probe, and ANQP. - Carrying access network information and roaming consortium data. * - Power Save - Retains legacy power saving features while enabling background service discovery. - Preserving battery life during Hotspot 2.0 and Passpoint interactions. * - Interoperability - Enables interworking with cellular and external networks using ANQP and Roaming Consortium info. - Seamless connectivity in public and carrier-grade Wi-Fi environments. * - Physical Rates - Inherits physical layer capabilities (e.g., OFDM rates) from base 802.11 standards. - Supporting high-speed connectivity with enhanced pre-auth and access mechanisms. * - PPDU - Standard PPDU format used; carries enhanced MAC management frames securely. - Delivering service discovery and access info in protected or unprotected frames. * - Channels - Same frequency bands and channel assignments as 802.11a (5 GHz), with focus on network discovery. - Efficient spectrum use with enhanced network advertisement capabilities * - PHY Overview - OFDM-based Physical Layer as in 802.11a, supporting higher layers for interworking and network selection. - High-speed data transmission supporting advanced service discovery and access control .. tab-set:: .. tab-item:: 802.11u (External Network Interworking) **Standard:** IEEE 802.11u (2011) **Main Features:** - Enables seamless interworking with external IP networks - Supports Hotspot 2.0 / Passpoint (public Wi-Fi roaming) - Introduces Access Network Query Protocol (ANQP) for network discovery - Facilitates user authentication prior to association - Provides network type, roaming consortium, and venue information - Allows for automatic connection decisions by the client **Use Cases:** - Public Wi-Fi hotspots (e.g., airports, cafés, hotels) - Carrier offload and mobile network roaming - Enterprise guest access without manual configuration - Streamlined access for SIM-based and credentialed users **Related Concepts:** - Hotspot 2.0 / Wi-Fi Passpoint - Access Network Query Protocol (ANQP) - Online Sign-Up (OSU) services - Roaming Consortium Organization Identifiers (OIs) - Venue Info, NAI Realm, IP address type availability - SIM-based authentication (EAP-SIM/AKA) .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore how 802.11u enables seamless Wi-Fi access:** * :ref:`Learnings in this section <802_11u_step1>` * :ref:`Terminology <802_11u_step2>` * :ref:`Version Info <802_11u_step3>` * :ref:`802_11u Version&IEEE Details <802_11u_step4>` * :ref:`802_11u Basic Setup on Ubuntu using IPv4 <802_11u_step5>` * :ref:`802_11u Basic Setup on Ubuntu using IPv6 <802_11u_step6>` * :ref:`Reference links <802_11u_step16>` .. button-link:: ./802_11u/802_11u.html :color: primary :shadow: :expand: Jump to "802.11u Basics" .. tab-set:: .. tab-item:: 802.11u MAC Functions **Standard:** IEEE 802.11u (2011) **Main Features:** - Manages interworking between Wi-Fi and external networks like cellular or ISP - Handles frame delimiting, addressing, and enhanced management frames for network discovery - Supports Generic Advertisement Service (GAS) for pre-association communication - Facilitates authentication and authorization with external networks - Enables seamless roaming and network selection based on operator policies - Works closely with higher layers for service advertisement and policy enforcement **Use Cases:** - Enabling smooth handoff between Wi-Fi and cellular networks - Allowing devices to discover and select networks dynamically - Supporting secure and managed access in heterogeneous network environments **Related Functions:** - Management frame extensions for interworking - Pre-association query and response exchanges (GAS) - Network selection and access control signaling - Integration with external authentication servers .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11u MAC Functions:** * :ref:`Reference links ` .. button-link:: ./802_11u/mac_functions.html :color: primary :shadow: :expand: Jump to "802.11u MAC Functions" .. tab-set:: .. tab-item:: 802.11u MAC Timings **Standard:** IEEE 802.11u (2011) **Main Features:** - Defines timing parameters for enhanced management and interworking frames - Supports timing coordination for Generic Advertisement Service (GAS) exchanges - Maintains synchronization for network discovery and access protocol interactions - Coordinates interframe spaces adapted for interworking services and authentication - Manages timing to minimize latency during network selection and roaming - Ensures smooth handoffs between Wi-Fi and external networks with precise timing control **Use Cases:** - Reducing delay in network discovery and authentication in heterogeneous networks - Coordinating timing of pre-association communication between devices and external servers - Supporting seamless roaming and inter-network handoff with minimal disruption **Related Timing Parameters:** - Short Interframe Space (SIFS) for fast frame exchanges - Distributed Interframe Space (DIFS) for contention-based access - GAS query/response timing windows - Timing coordination with external authentication and policy servers .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11u MAC Timings:** * :ref:`Reference links ` .. button-link:: ./802_11u/mac_timings.html :color: primary :shadow: :expand: Jump to "802.11u MAC Timings" .. tab-set:: .. tab-item:: 802.11u Packet Formats **Standard:** IEEE 802.11u (2011) **Main Features:** - Defines frame structures for enhanced management and interworking information exchange - Supports new Information Elements (IEs) for network discovery and access selection - Includes frames for Generic Advertisement Service (GAS) and Access Network Query Protocol (ANQP) - Supports interworking with external networks via additional frame fields - Maintains compatibility with existing 802.11 management and control frame formats - Enables extensible frame formats for conveying policy, roaming, and service info **Use Cases:** - Exchanging interworking capabilities and roaming consortium info with networks - Facilitating pre-association service discovery and authentication - Supporting seamless handoffs and network selection based on enriched frame data **Related Frame Types:** - Enhanced management frames with new IEs (e.g., Interworking IE, Roaming Consortium IE) - GAS frames for service advertisement - ANQP frames for detailed network information queries .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11u Packet Formats:** * :ref:`Reference links ` .. button-link:: ./802_11u/packet_formats.html :color: primary :shadow: :expand: Jump to "802.11u Packet Formats" .. tab-set:: .. tab-item:: 802.11u Power Saving Mechanisms **Standard:** IEEE 802.11u (2011) **Main Features:** - Enhances power saving by enabling efficient interworking with external networks - Supports mechanisms for network discovery and selection with minimal power use - Allows client devices to query network capabilities before association, reducing unnecessary wake-ups - Facilitates reduced scanning times via Generic Advertisement Service (GAS) and Access Network Query Protocol (ANQP) - Works alongside 802.11 power saving modes to optimize battery life during roaming and network access - Supports energy-efficient transitions between networks including cellular and Wi-Fi **Use Cases:** - Extending battery life during complex multi-network discovery and roaming - Reducing power consumption for mobile devices in heterogeneous network environments - Improving user experience by minimizing delays and power overhead in network selection **Related Mechanisms:** - GAS protocol for efficient service discovery - ANQP for querying network attributes with minimal traffic - Integration with existing 802.11 Power Save Mode (PSM) .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11u Power Saving mechanisms:** * :ref:`Reference links ` .. button-link:: ./802_11u/power_save.html :color: primary :shadow: :expand: Jump to "802.11u Power Saving" .. tab-set:: .. tab-item:: 802.11u Interoperability **Standard:** IEEE 802.11u (2011) **Main Features:** - Facilitates seamless interworking between Wi-Fi networks and external networks like cellular - Enables network discovery and selection across heterogeneous access networks - Supports standardized information exchange via Access Network Query Protocol (ANQP) - Enhances roaming capabilities with improved network authentication and service discovery - Defines protocols for smooth handoff and session continuity across network types - Supports multi-vendor interoperability through clear protocol specifications **Use Cases:** - Allowing mobile devices to switch seamlessly between Wi-Fi and cellular networks - Enabling service providers to offer unified connectivity experiences - Supporting public hotspots that integrate with cellular operator networks **Related Mechanisms:** - Access Network Query Protocol (ANQP) - Generic Advertisement Service (GAS) - Network authentication and authorization frameworks - Interworking with 3GPP cellular networks .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11u Interoperability mechanisms:** * :ref:`Reference links ` .. button-link:: ./802_11u/interoperability.html :color: primary :shadow: :expand: Jump to "802.11u Interoperability" .. tab-set:: .. tab-item:: 802.11u Physical Rates **Standard:** IEEE 802.11u (2011) **Main Features:** - Builds on existing 802.11 PHY standards (like 802.11a/b/g/n) for physical layer operations - Does not define new physical rates but leverages rates from underlying PHY standards - Supports adaptive rate selection through underlying 802.11 PHY mechanisms - Enables seamless handoff and network selection without impacting physical data rates - Operates on standard Wi-Fi frequency bands (2.4 GHz and 5 GHz) depending on underlying PHY - Ensures compatibility with legacy PHY rate adaptation and modulation schemes **Use Cases:** - Facilitating interworking while maintaining physical layer performance - Supporting mobile devices switching across heterogeneous networks without PHY disruption - Ensuring smooth user experience with consistent data rates during roaming **Related Concepts:** - Rate adaptation and selection inherited from base PHY standards (802.11a/b/g/n/ac) - Network discovery and selection protocols at higher layers - Seamless session continuity without physical layer impact .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the relationship of 802.11u with Physical Rates:** * :ref:`physical_rates in 802.11u ` * :ref:`Reference links ` .. button-link:: ./802_11u/physical_rates.html :color: primary :shadow: :expand: Jump to "802.11u Physical Rates" .. tab-set:: .. tab-item:: 802.11u PPDU **Standard:** IEEE 802.11u (2011) **Main Features:** - Relies on PPDU formats defined in underlying 802.11 PHY standards (e.g., 802.11a/n/ac) - Does not define a new PPDU structure but enables interworking across networks - Supports higher-layer signaling without modifying physical layer frame formats - Ensures compatibility with existing OFDM or DSSS modulations as per PHY standard - Maintains synchronization and data integrity through inherited PPDU mechanisms - Enables smooth transition and roaming without physical layer changes **Use Cases:** - Facilitating network selection and authentication without altering PHY frames - Supporting enhanced roaming and access network discovery at upper layers - Ensuring reliable data transmission through stable PHY layer encapsulation **Related Concepts:** - Underlying PHY PPDU structures (OFDM, DSSS) - Higher layer network selection and authentication messages - Frame encapsulation and MAC/PHY coordination .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore how 802.11u interacts with PPDU formats:** * :ref:`Reference links ` .. button-link:: ./802_11u/ppdu.html :color: primary :shadow: :expand: Jump to "802.11u PPDU" .. tab-set:: .. tab-item:: 802.11u Channels **Standard:** IEEE 802.11u (2011) **Main Features:** - Operates in the same 5 GHz UNII bands with 20 MHz channel bandwidth as 802.11a - Supports network discovery and interworking enhancements on existing channels - Utilizes the same channel allocation principles as 802.11a, including DFS and TPC - Enables enhanced service advertisement and access on established 5 GHz channels - Maintains channel separation of at least 20 MHz to reduce interference - Designed to improve roaming and access to external networks without modifying PHY layer **Use Cases:** - Facilitating network selection and interworking with cellular and external networks - Enhancing user experience through seamless roaming in heterogeneous environments - Maintaining reliable wireless connectivity with advanced service discovery **Related Concepts:** - UNII bands (UNII-1, UNII-2, UNII-3, UNII-2E) - DFS (Dynamic Frequency Selection) and TPC (Transmit Power Control) - Access Network Query Protocol (ANQP) and Generic Advertisement Service (GAS) - Interworking with external networks (e.g., cellular) .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11u Channels:** * :ref:`List of channels ` * :ref:`List of channel widths ` * :ref:`List of Bands ` * :ref:`Reference links ` .. button-link:: ./802_11u/channels.html :color: primary :shadow: :expand: Jump to "802.11u Channels" .. tab-set:: .. tab-item:: 802.11u PHY **Standard:** IEEE 802.11u (2011) **Main Features:** - Builds upon the IEEE 802.11a OFDM physical layer specifications - Supports data rates and modulation schemes identical to 802.11a (6 Mbps to 54 Mbps) - Employs 52 subcarriers: 48 for data, 4 for pilot signals, same as 802.11a - Incorporates physical layer enhancements enabling interworking and network discovery at higher layers - Uses 20 MHz channel bandwidth with 4 µs OFDM symbol duration in the 5 GHz band - Maintains high-speed, reliable wireless transmission while enabling advanced network selection features **Use Cases:** - Enabling seamless interworking with external networks without changing the physical layer - Supporting robust wireless transmission for enhanced roaming and service discovery - Delivering multimedia and data services with consistent PHY performance **Related Concepts:** - OFDM modulation and subcarrier mapping inherited from 802.11a - Integration with higher-layer protocols like ANQP and GAS for interworking - Preamble, SIGNAL field, and synchronization aligned with 802.11a standards .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11u PHY:** * :ref:`Reference links ` .. button-link:: ./802_11u/PHYs.html :color: primary :shadow: :expand: Jump to "802.11u PHY"