Wireless LAN Data Unit Transmission with 1 MHz Bandwidth and Pilot Tones
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Solution Overview
Problem
Existing wireless LAN systems operating above 1 GHz frequency have limited service coverage and cannot efficiently manage a large number of stations, necessitating a new data unit and transmission method for next-generation wireless LAN systems operating below 1 GHz frequency.
Innovation Solution
A method for transmitting data units in a wireless LAN system using a 1 MHz channel bandwidth with inserted pilot tones and varying guard intervals, supporting PPDU formats for 1/2/4/8/16/8+8 MHz channel bandwidths, enabling efficient data transmission and reception with extended service coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If wireless LAN systems operate above 1 GHz frequency with existing data unit formats, then data transmission is supported, but service coverage is limited and the number of manageable stations is restricted
Solution Approach 1:
The patent applies dynamics by making the guard interval length variable rather than fixed. The system dynamically selects between short guard interval (SGI) and long guard interval (LGI) based on channel conditions and transmission requirements. This dynamic adaptation allows the same data unit format to work efficiently across different frequency bands and coverage areas, resolving the contradiction between extended coverage and format compatibility
Solution Approach 2:
The patent changes key parameters of the data unit format including guard interval length, pilot tone insertion patterns, and subcarrier spacing to optimize performance for below-1-GHz operations. By modifying these parameters while maintaining the overall PPDU structure, the system achieves extended service coverage without complete format redesign, thus resolving the contradiction between coverage extension and complexity increase
2Measurement precision
If pilot tones are inserted into data symbols for frequency below 1 GHz, then channel estimation accuracy is improved, but data transmission overhead increases
Solution Approach 1:
The patent applies local quality by inserting pilot tones only at specific subcarrier positions (e.g., every 8th subcarrier) rather than uniformly across all subcarriers. This localized pilot insertion provides sufficient channel estimation accuracy for below-1-GHz operations while minimizing the overhead burden on data transmission capacity
Solution Approach 2:
The patent uses partial action by inserting a reduced number of pilot tones compared to traditional high-frequency WLAN systems. The pilot insertion pattern is optimized to provide just enough estimation accuracy for the lower frequency band characteristics, avoiding excessive overhead while maintaining adequate channel state information for reliable transmission
3Productivity
If short guard interval is applied to data symbols, then transmission efficiency is improved, but susceptibility to multipath interference increases
Solution Approach 1:
The patent implements dynamic guard interval selection where the system can switch between SGI and LGI based on detected channel conditions. When multipath delay is small, SGI is used for high efficiency; when multipath delay is large, LGI is selected for improved reliability. This dynamic approach resolves the contradiction by adapting to actual transmission conditions
Solution Approach 2:
The patent segments the data transmission into multiple PPDU frames, each with independently selectable guard intervals. This allows different portions of data to use different guard interval lengths optimized for their specific channel conditions, achieving both high overall efficiency and reliable transmission across varying multipath environments
Data Source
AI summary
Provided is a method for transmitting a data unit in a wireless local area network system, according to one embodiment. The method comprises transmitting a signal field, transmitting a first data symbol for a first data field, and transmitting a second data symbol for a second data field. The signal field, the first data symbol, and the second data symbol are transmitted through a 1 MHz channel bandwidth having a band of 1 GHz or less. Two pilot tones are inserted to each of the first data symbol and the second data symbol.