STF Signal Generation Using Repeated M-Sequence Patterns
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Solution Overview
Problem
Next-generation wireless LAN systems face challenges in improving spectrum efficiency and area throughput, especially in dense environments with multiple access points and stations, and require efficient methods for generating short training field (STF) signals that can support multiple frequency bands.
Innovation Solution
A method for generating a short training field (STF) signal in wireless LAN systems using a predetermined M sequence repeated in specific patterns, such as {M, 1, −M, −M}*(1+j)/sqrt(2), to support multiple frequency bands, enhancing the STF signal for improved performance across different bandwidths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional STF sequence is used, then the system is simple to implement, but it cannot efficiently support multiple frequency bands and dense environments
Solution Approach 1:
The STF sequence is segmented into multiple M-sequences of length 15, which are then repeated and combined to form sequences suitable for different frequency bands (20 MHz, 40 MHz, 80 MHz). This segmentation allows a single base sequence design to serve multiple bandwidth requirements without redesigning the entire sequence for each band.
Solution Approach 2:
The patent creates a universal STF sequence generation method that can be applied across multiple frequency bands (2.4 GHz and 5 GHz, 20/40/80 MHz) using the same M-sequence repetition pattern. The sequence {M, 1, -M, 0, -M, 1, -M} serves as a universal template that adapts to different bandwidth requirements through repetition, eliminating the need for band-specific sequence designs.
2Productivity
If the STF signal is enhanced for better performance, then spectrum efficiency improves, but the sequence generation becomes more complex
Solution Approach 1:
The patent employs periodic repetition of M-sequences to generate STF signals with enhanced spectral properties. By repeating the base M-sequence multiple times and combining them with specific patterns (including zeros and sign inversions), the signal achieves better spectral efficiency and autocorrelation properties without requiring complex modulation schemes.
Solution Approach 2:
The patent optimizes STF signal parameters by adjusting the repetition pattern of M-sequences, the insertion of zero values, and sign inversions at specific positions. These parameter changes enhance the signal's spectral efficiency and autocorrelation characteristics while maintaining a relatively simple generation structure based on repeated patterns.
3Adaptability or versatility
If a longer sequence is used to support wider bandwidths, then multi-band compatibility improves, but the transmission time increases
Solution Approach 1:
The patent segments the STF sequence into multiple 15-length M-sequences that can be independently repeated and combined. This segmentation allows the system to create longer sequences for wider bandwidths by simple repetition rather than using a single long primitive sequence, thereby maintaining temporal efficiency while achieving bandwidth adaptability.
Solution Approach 2:
The patent uses partial repetition of M-sequences with strategic insertion of zero values and sign inversions to achieve the necessary sequence length for wide bandwidth support without simply extending the sequence linearly. This approach provides sufficient sequence length for 80 MHz bands while minimizing the increase in transmission duration compared to straightforward extension methods.
Data Source
AI summary
Disclosed are a method and an apparatus for generating an STF signal usable in a wireless LAN system. The STF signal is included in a field used to improve AGC estimation of a MIMO transmission. The STF signal that is suggested, for example, can be used for an 80 MHz band and can be generated based on a sequence in which a predetermined M sequence is repeated. Also, the disclosed STF signal can be used for a 1×STF signal from the 1×STF signal and a 2×STF signal. The predetermined M sequence can be a binary sequence of which the length is 15 bits.