Dynamic Frame Symbol Length Adjustment for HE WLAN
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Solution Overview
Problem
Current WLAN technologies face challenges in efficiently transmitting frames in outdoor environments due to the limitations of existing guard intervals, which affect symbol length and throughput, especially in high efficiency (HE) WLANs.
Innovation Solution
The method involves generating frames with varying symbol lengths by adjusting subcarrier spacing and using inverse and Fourier transforms to include symbols with durations of 3.2 μs, 6.4 μs, and 12.8 μs, along with specific modulation techniques and subcarrier allocations to enhance channel estimation and data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the guard interval length is increased to improve robustness in outdoor environments, then the symbol duration increases, but the throughput decreases due to longer transmission time
Solution Approach 1:
The patent implements dynamic symbol length adjustment by supporting multiple symbol durations (3.2 μs, 6.4 μs, and 12.8 μs) that can be selected based on channel conditions. The system can adaptively choose shorter symbols for good channel conditions to maximize throughput, and longer symbols for poor conditions to maintain robustness, thus dynamically optimizing the trade-off between reliability and productivity.
Solution Approach 2:
The patent changes the subcarrier spacing parameter to achieve different symbol durations. By adjusting the subcarrier spacing (narrower spacing for longer symbols), the system can transform the symbol length parameter to match channel requirements, enabling flexible adaptation between throughput optimization and robustness enhancement without being constrained by fixed guard interval lengths.
2Reliability
If the symbol length is increased to improve robustness, then the guard interval can be extended, but the transmission time increases reducing efficiency
Solution Approach 1:
The patent segments the transmission into different symbol types with varying lengths (3.2 μs, 6.4 μs, 12.8 μs). Instead of using a single long symbol for all transmissions, the system divides the data stream into segments that can be transmitted with appropriately sized symbols, allowing shorter symbols to be used where possible to minimize transmission time while longer symbols provide robustness where needed.
Solution Approach 2:
The system dynamically selects symbol lengths based on channel conditions and transmission requirements. This dynamic adaptation allows the system to minimize transmission time by using shorter symbols when channel conditions permit, while only employing longer symbols when robustness is critical, thus reducing overall transmission time compared to always using long symbols.
3Reliability
If narrower subcarrier spacing is used to generate longer symbols, then the symbol duration increases for better outdoor performance, but the system complexity increases due to additional transform operations
Solution Approach 1:
The patent achieves longer symbol durations by changing the subcarrier spacing parameter rather than fundamentally altering the signal processing architecture. By adjusting this key parameter, the system can generate symbols of different lengths (3.2 μs, 6.4 μs, 12.8 μs) using the same basic OFDM framework, avoiding the need for completely different processing systems and thus limiting the increase in device complexity.
Data Source
AI summary
A method of transmitting a frame by a device in a wireless communication network is provided. The device generates a first symbol having a first subcarrier spacing where a symbol duration of the first symbol, excluding a guard interval, has a first length. The device generates a second symbol having a second subcarrier spacing narrower than the first subcarrier spacing wherein a symbol duration of the second symbol, excluding a guard interval, has a second length that is twice the first length. The device transmits a frame including the first symbol and the second symbol.