ELR PPDU Frame Structure for Long-Range WLAN Uplink Decoding
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Solution Overview
Problem
The discrepancy in transmission power between access points (APs) and non-AP stations (STAs) in wireless LAN systems leads to unequal downlink and uplink signal transmission ranges, necessitating improved frame structures for long-range communication.
Innovation Solution
A new physical protocol data unit (PPDU) structure is proposed, incorporating an Enhanced Long Range (ELR) PPDU with a frequency-mapped data field, including an ELR-SIG field duplicated in the frequency domain to enhance transmission range and ensure accurate decoding, even in cases where existing L-SIG and U-SIG fields are not successfully received.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the TX power of AP is increased to extend downlink transmission range, then the downlink signal transmission range is improved, but the uplink transmission range remains limited due to STA power constraints
Solution Approach 1:
The patent segments the transmission range problem into separate downlink and uplink components, addressing each with appropriate mechanisms. The downlink extends range through AP power enhancement and beamforming, while the uplink uses feedback mechanisms and adaptive power control to compensate for STA power limitations, resolving the asymmetry between the two directions.
Solution Approach 2:
The patent employs parameter changes by dynamically adjusting transmission power, beamforming vectors, and feedback coefficients based on channel conditions. The system changes power levels and spatial parameters adaptively to optimize both downlink transmission range and uplink reception quality, overcoming the fixed power constraint of STAs.
2Length of stationary object
If a new PPDU structure with ELR-SIG field is introduced to enable extended range transmission, then the transmission range is improved, but the frame format complexity increases
Solution Approach 1:
The patent implements nesting by embedding the ELR-SIG field within the existing PPDU structure, placing it after the legacy signal field. The ELR-SIG contains condensed information about the extended range data field, allowing receivers to efficiently interpret the enhanced PPDU without requiring a complete redesign of the frame format, thus managing complexity while enabling extended range.
Solution Approach 2:
The patent applies preliminary action by including the ELR-SIG field before the actual extended range data transmission. This preliminary signal field provides essential information about the data field's characteristics (such as modulation and coding scheme) in advance, allowing receivers to prepare for accurate decoding of the subsequent data, thereby reducing overall system complexity.
3Length of stationary object
If frequency mapping techniques are improved in the PPDU data field to increase transmission range, then the signal transmission range is extended, but the decoding accuracy may be compromised without proper signal field definitions
Solution Approach 1:
The patent implements feedback mechanisms through the ELR-SIG field, which provides receivers with essential information about the frequency-mapped data field's parameters. This feedback includes modulation indices, coding rates, and resource unit allocations, enabling receivers to accurately decode the frequency-mapped data without ambiguity, thus maintaining decoding accuracy while extending transmission range.
Solution Approach 2:
The ELR-SIG field acts as an intermediary between the frequency-mapped data field and the receiver. It mediates the complexity of frequency mapping by providing a simplified interface with key parameters, allowing receivers to interpret the frequency-domain data correctly without needing to directly process the complex mapping relationships, thereby ensuring accurate decoding.
Data Source
AI summary
This disclosure may propose a method for transmitting/receiving a physical protocol data unit (PPDU) with an improved structure and a device related thereto. A station (STA) related to this disclosure can generate an ELR PPDU that includes a data field. The ELR PPDU may include a legacy signal (L-SIG) field containing information related to the length of the ELR PPDU and a universal signal (U-SIG) field containing information for interpreting the ELR PPDU. For example, the L-SIG field, the RL-SIG field, and the U-SIG field may be generated based on the first subcarrier frequency spacing. For example, the ELR PPDU may further include a Short Training Field (STF), a Long Training Field (LTF), an ELR Signal (ELR-SIG) field, and a data field. For example, the STF, the LTF, the ELR-SIG field, and the data field may be generated based on the second subcarrier frequency spacing.