List of PPDUs Supported in 802.11ah
========================================


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        **What is a PPDU in 802.11ah?**

        PPDU stands for Physical Protocol Data Unit and is the packet format used for transmission at the physical layer in 802.11ah.

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        **What are the main components of the 802.11ah PPDU?**

        The PPDU consists of the preamble, signal field, service field, data payload, and tail bits.

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        **What is the purpose of the preamble in the PPDU?**

        The preamble helps the receiver synchronize timing, frequency, and channel estimation before receiving the data.

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        **How does the SIGNAL field function in 802.11ah PPDU?**

        It contains information about data rate, modulation, coding scheme, and the length of the packet.

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        **What modulation technique is used for the PPDU payload in 802.11ah?**

        OFDM (Orthogonal Frequency Division Multiplexing) is used for the PPDU payload modulation.

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        **How does 802.11ah PPDU support different data rates?**

        By varying modulation types and coding rates specified in the SIGNAL field.

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        **What is the role of the service field in the PPDU?**

        It provides padding and scrambling initialization for better error resilience.

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        **What are tail bits in the PPDU?**

        Tail bits are appended to terminate convolutional coding for accurate decoding.

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        **Does 802.11ah PPDU support different channel bandwidths?**

        Yes, it supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz channels.

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        **How does the preamble length vary in 802.11ah PPDU?**

        Preamble length depends on the channel bandwidth and PHY type.

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        **What is the typical duration of an 802.11ah PPDU?**

        It varies widely depending on data rate and packet size, from a few milliseconds up to tens of milliseconds.

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        **How does 802.11ah PPDU ensure synchronization?**

        The preamble includes special sequences used for timing and frequency synchronization.

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        **What is the difference between Legacy and High Throughput PPDU in 802.11ah?**

        Legacy PPDU uses basic modulation with longer preambles; High Throughput PPDU supports advanced modulation and coding schemes for faster rates.

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        **How does 802.11ah PPDU handle error detection?**

        Through cyclic redundancy check (CRC) fields in the MAC frame, protected by the PHY coding.

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        **Can the PPDU format be extended for future features?**

        Yes, the protocol allows extensions for enhanced features while maintaining backward compatibility.

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        **What is the significance of OFDM symbols in the PPDU?**

        OFDM symbols carry the encoded data and pilot tones for channel estimation.

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        **How is power efficiency considered in PPDU transmission?**

        Short preambles and efficient coding reduce transmission time, saving energy in battery-powered devices.

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        **How does 802.11ah PPDU support long-range communication?**

        By using narrow bandwidths and robust modulation schemes to maintain signal integrity over distance.

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        **Is the PPDU structure similar to other 802.11 standards?**

        It follows a similar basic structure but is optimized for sub-1 GHz operation and IoT use cases.


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        Topics in this section,

                * :ref:`Reference links <ppdu_ah_step17>`


.. _ppdu_ah_step17:

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    .. tab-item:: Reference links
     
       * Reference links