Wireless LAN Preamble Configuration for OFDMA Tone Allocation
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Solution Overview
Problem
The IEEE 802.11ax wireless communication standard faces challenges in configuring and transmitting preambles to support high-speed communication in high-density environments, particularly in coexisting with legacy terminals, which requires efficient use of time and frequency tones while maintaining compatibility with existing standards.
Innovation Solution
A method for configuring radio frames with distinct preamble lengths for different terminal types, including a short training field (STF) and long training field (LTF), where the preamble for the second type of terminal is assigned at an integer multiple of tones in the frequency domain, optimizing tone usage and supporting OFDMA and UL-MU MIMO.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a unified preamble structure is used for both legacy terminals and IEEE 802.11ax terminals, then compatibility with existing standards is maintained, but communication efficiency and resource utilization deteriorate in high-density environments
Solution Approach 1:
The radio frame is segmented into distinct portions: a legacy frame portion with preamble for legacy terminals, and an IEEE 802.11ax frame portion with extended preamble for ax terminals. This segmentation allows each terminal type to process only its designated frame portion, improving overall system efficiency while maintaining legacy compatibility
Solution Approach 2:
Different preamble structures are applied to different frame portions based on terminal type requirements. The legacy frame portion uses traditional preamble structure, while the ax frame portion uses extended preamble with additional fields, optimizing each section for its specific terminal type
2Adaptability or versatility
If the preamble length is extended to support additional fields for IEEE 802.11ax terminals, then communication capabilities are enhanced, but time domain overhead increases
Solution Approach 1:
The frame structure is divided such that legacy terminals process only the shorter legacy frame portion, while ax terminals process the extended ax frame portion. This segmentation ensures that legacy terminals do not incur the time overhead of the extended preamble, while ax terminals benefit from the enhanced capabilities
Solution Approach 2:
The extended preamble fields are included only when needed for ax terminal communication. The frame structure allows partial processing where legacy terminals ignore the extended portions, effectively reducing the time overhead impact to only the necessary ax terminal communications
3Speed
If frequency tones are densely packed to increase data rate, then transmission speed improves, but interference between users increases in high-density environments
Solution Approach 1:
The frequency spectrum is segmented into different resource units that can be independently allocated to different users. This segmentation enables orthogonal frequency division multiple access (OFDMA) where each user receives interference-free tones, maintaining high transmission rates while reducing user-to-user interference in dense environments
Data Source
AI summary
Disclosed is a method for transmitting a preamble in a wireless LAN system, and a station device for performing the same. To this end, a station for transmitting a preamble configures a wireless frame including a first type terminal frame portion, and a second type terminal frame portion. The first type terminal frame portion includes a first type terminal preamble including a first type terminal short training field (STF) and a first type terminal long training field (LTF), and the second type terminal frame portion includes a second type terminal preamble including a second type terminal SFT and a second type terminal LTF. Here, the station configures the second type terminal preamble by allocating sequence components at an interval of an integer number of tones in a frequency domain and transmits the configured wireless frame to another station.