802.11u MAC Functions
=========================


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        **What are the primary MAC functions enhanced by IEEE 802.11u?**

        802.11u extends MAC functions to support network discovery, pre-association queries, and interworking with external networks.

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        **How does 802.11u handle MAC layer network selection?**

        It enables MAC to process ANQP responses before association to choose the most appropriate network.

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        **Does 802.11u modify frame formats at the MAC layer?**

        Yes, it introduces new Information Elements (IEs) in management frames to carry additional interworking and network info.

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        **What role does the MAC layer play in GAS (Generic Advertisement Service)?**

        The MAC layer provides the transport mechanism for GAS frames, allowing ANQP queries and responses between clients and APs.

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        **How does 802.11u improve MAC layer authentication?**

        It supports more dynamic and seamless authentication methods facilitating roaming and interworking at the MAC level.

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        **Are there any MAC timing changes in 802.11u?**

        While MAC timing principles remain, 802.11u may affect timing by adding pre-association query exchanges via GAS.

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        **Does 802.11u affect power saving features at the MAC layer?**

        Indirectly, yes—by optimizing network selection and reducing scanning times, it can help conserve device battery life.

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        **How does 802.11u support interworking with cellular networks at the MAC level?**

        It allows MAC management frames to carry interworking information elements that aid seamless roaming between Wi-Fi and cellular.

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        **What new management frames or elements are introduced by 802.11u in MAC?**

        802.11u introduces elements like Access Network Type, Roaming Consortium, Venue Info, and Emergency Alert within MAC management frames.

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        **Does 802.11u support backward compatibility at the MAC layer?**

        Yes, it ensures legacy devices can still associate normally while enabling enhanced functions for 802.11u-capable devices.

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        **How does 802.11u MAC layer support faster network handoffs?**

        By pre-fetching network information and supporting seamless authentication processes at the MAC level.

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        **Are fragmentation or retransmission mechanisms altered in 802.11u MAC?**

        No, core MAC reliability mechanisms like fragmentation and retransmission remain unchanged.

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        **How does 802.11u assist in emergency services at the MAC layer?**

        It enables MAC frames to advertise emergency services availability, helping devices identify suitable networks quickly.

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        **What is the role of MAC in managing network access for guest users in 802.11u?**

        MAC functions help support guest network identification and appropriate access control using new interworking elements.

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        **Does 802.11u MAC layer support QoS enhancements?**

        It complements existing QoS by enabling network selection based on service capabilities, indirectly supporting QoS improvements.

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        **How is MAC security impacted by 802.11u?**

        802.11u facilitates stronger authentication and network selection security through enhanced info elements and protocols.

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        **Are there any new MAC timers or counters introduced by 802.11u?**

        No new timers or counters are specifically introduced, but additional frame exchanges may affect overall timing.

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        **How does 802.11u MAC layer affect multi-SSID or virtual AP operation?**

        It supports broadcasting interworking info on multiple SSIDs, enhancing user choice across virtual networks.


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        Topics in this section,

                * :ref:`Reference links <mac_functions_u_step17>`


.. _mac_functions_u_step17:

.. tab-set::

    .. tab-item:: Reference links

       * Reference links