Variable Guard Interval PPDU for WLAN Interference and Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Next-generation wireless local area networks (WLANs) face challenges in enhancing spectrum efficiency and area throughput, especially in dense environments with multiple access points and stations, and require improved performance in both indoor and outdoor settings, including overlapping basic service sets and cellular off-loading, while maintaining compatibility with legacy systems.
Innovation Solution
The method involves generating and transmitting PHY protocol data units (PPDUs) with varying guard interval lengths, using different inverse fast Fourier transform (IFFT) sizes for distinct OFDM symbols, which allows for efficient data transmission across multiple OFDM symbols, thereby optimizing symbol duration and resistance to interference in diverse environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniform guard interval length is used for all OFDM symbols, then the system structure is simple, but the interference resistance and spectral efficiency are reduced in dense environments
Solution Approach 1:
The patent changes the guard interval parameter from a fixed uniform value to variable lengths across different OFDM symbols. Specifically, the first OFDM symbol uses a first guard interval length while subsequent OFDM symbols use a second guard interval length that is shorter than the first. This parameter variation optimizes interference resistance for legacy compatibility while improving spectral efficiency for new transmissions.
Solution Approach 2:
The patent segments the guard interval structure into at least two distinct parts: a first guard interval for the first OFDM symbol and a second guard interval for subsequent OFDM symbols. This segmentation allows different guard interval lengths to be applied to different portions of the transmission, enabling optimized performance for both legacy and next-generation WLAN requirements.
2Reliability
If longer guard intervals are used, then interference resistance improves, but spectral efficiency and area throughput decrease
Solution Approach 1:
The patent applies parameter changes by using a longer first guard interval length for the first OFDM symbol to ensure robust interference resistance, then transitions to a shorter second guard interval length for subsequent OFDM symbols to improve spectral efficiency. This dynamic parameter adjustment resolves the contradiction between reliability and productivity.
3Productivity
If shorter guard intervals are used, then spectral efficiency improves, but interference resistance and robustness in dense environments deteriorate
Solution Approach 1:
The patent uses parameter changes to apply shorter guard interval lengths to subsequent OFDM symbols after the first symbol, thereby improving spectral efficiency and area throughput while maintaining adequate interference resistance through the longer first guard interval.
4Adaptability or versatility
If different IFFT sizes are used for different fields, then transmission robustness and adaptability improve, but processing complexity increases
Solution Approach 1:
The patent changes the IFFT size parameter from a single uniform value to at least two different values: a first IFFT size for generating the first OFDM symbol and a second IFFT size for generating subsequent OFDM symbols. This enables adaptability to different transmission conditions while managing processing complexity through structured parameter variation.
Data Source
AI summary
Disclosed are a method and an apparatus for transmitting a data unit comprising guard intervals having different lengths. A method for transmitting a data unit in a wireless LAN comprises the steps of: a transmission STA generating a PPDU; and the transmission PPDU transmitting the PPDU to one or more reception STAs, wherein the PPDU sequentially comprises a first signal field, a second signal field, and a training field, wherein the first signal field is generated on the basis of a first IFFT size and is transmitted in a first OFDM symbol, the second signal field is generated on the basis of the first IFFT size and is transmitted in a second OFDM symbol, and the training field is generated on the basis of a second IFFT size and is transmitted in a third OFDM symbol.