Low Bandwidth PHY Transmission Edge Tone Shaping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current wireless local area networks (WLANs) operating in sub-1 GHz frequencies face challenges in spectral mask compliance due to the reduced number of guard tones in low bandwidth mode data units, which can violate spectral mask requirements when positioned within wider channel bandwidths.
Innovation Solution
The method involves duplicating low bandwidth mode data units within a BSS channel, with specific tone maps and phase rotations, and modifying data tones at the edges to meet spectral mask requirements, including scaling down or zeroing out tones to ensure compliance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If low bandwidth mode data units are transmitted with reduced guard tones to improve spectral efficiency, then data transmission efficiency is improved, but spectral mask compliance deteriorates
Solution Approach 1:
The patent applies local quality by differentiating the treatment of OFDM tones based on their position within the channel bandwidth. Edge tones receive special processing (reduction or zeroing) while central tones maintain full power, creating localized quality variations that satisfy spectral mask requirements at band edges while preserving data transmission efficiency in the central region.
Solution Approach 2:
The patent changes the power parameter of specific OFDM tones dynamically based on their frequency position. By adjusting the amplitude parameter of edge tones (reducing or zeroing them) while maintaining central tones at full power, the system adapts to spectral mask constraints without sacrificing overall transmission efficiency.
2Length of moving object
If data tones at channel edges are transmitted at full power to maintain signal strength, then communication range is improved, but spectral mask violations occur
Solution Approach 1:
The patent applies preliminary anti-action by preemptively reducing or zeroing the power of edge tones before transmission. This preventive measure counteracts the potential harmful spectral leakage and mask violations that would otherwise occur, allowing the system to maintain extended communication range through central tones while preventing edge-related spectral violations.
3Reliability
If stricter front-end filter requirements are imposed to ensure spectral mask compliance, then spectral mask compliance is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by performing spectral shaping directly in the frequency domain during OFDM signal generation, before the signal reaches the front-end filters. By pre-reducing or zeroing edge tones to comply with spectral masks, the system eliminates the need for complex analog filtering, thereby maintaining spectral compliance while reducing device complexity.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method for generating signals to be transmitted within a BSS channel, where a set of component channels is collectively coextensive with the BSS channel, includes determining that a first duplicate, in frequency, of a low bandwidth mode data unit will be located at an edge of the BSS channel. Each duplicate includes OFDM tones and has a bandwidth less than the narrowest channel of the component channels. The OFDM tones in each duplicate include one or more data tones, one or more pilot tones, and one or more guard tones. The method also includes generating a transmission signal comprising the duplicates, at least in part by scaling down at least one data tone, and/or zeroing out at least one data tone, of the first duplicate in response to determining that the first duplicate will be located at an edge of the BSS channel.