802.11ah PHYs
What frequency band does the 802.11ah PHY operate in?
The 802.11ah PHY operates primarily in the sub-1 GHz unlicensed bands (around 900 MHz).
What modulation schemes does 802.11ah PHY support?
It supports various modulation schemes including BPSK, QPSK, 16-QAM, and 64-QAM.
What channel bandwidths are defined for 802.11ah PHY?
Channel bandwidths include 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz.
How does 802.11ah PHY achieve long-range communication?
By operating at lower frequencies with narrow channel bandwidths and using robust modulation and coding schemes.
What type of OFDM does 802.11ah PHY use?
It uses OFDM tailored for narrowband channels with longer symbol durations to improve resilience.
What is the maximum data rate supported by 802.11ah PHY?
The maximum theoretical data rate is approximately 347 Mbps under ideal conditions.
How does 802.11ah PHY handle multipath fading?
It employs convolutional coding, interleaving, and robust OFDM subcarrier modulation to mitigate multipath effects.
What is the OFDM symbol duration in 802.11ah PHY?
Symbol duration varies by channel bandwidth, generally longer than traditional Wi-Fi to support longer range.
Does 802.11ah PHY support MIMO?
No, 802.11ah primarily uses single-antenna (SISO) PHY for power efficiency and simplicity.
How does 802.11ah PHY differ from 802.11ac PHY?
802.11ah targets sub-1 GHz bands with narrow channels and low power for IoT, while 802.11ac operates at 5 GHz with wider channels and MIMO.
What coding schemes does 802.11ah PHY use?
It uses convolutional coding with different rates to balance throughput and reliability.
How is synchronization achieved in 802.11ah PHY?
Via preambles designed for coarse and fine timing and frequency synchronization.
What is the role of the SIGNAL field in 802.11ah PHY?
It carries information about data rate, length, and coding used for proper frame decoding.
How does 802.11ah PHY manage power consumption?
By using narrow bandwidths, low-order modulations, and efficient coding, it reduces power needs.
Is 802.11ah PHY backward compatible with other 802.11 standards?
No, it is designed specifically for sub-1 GHz and differs significantly in PHY layer.
What type of channel coding interleaving is used in 802.11ah PHY?
Bit interleaving is used to spread errors and improve error correction performance.
Does 802.11ah PHY support adaptive modulation and coding?
Yes, it dynamically adjusts modulation and coding based on channel quality.
What applications benefit from 802.11ah PHY?
IoT sensor networks, smart agriculture, smart cities, and long-range low power wireless communications.
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