Low-PAPR LTF Sequences for Wideband WLAN PPDU Transmission
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Solution Overview
Problem
The existing IEEE 802.11ax standard struggles to meet the increasing demands for high throughput, low latency, and low jitter due to high peak-to-average power ratio (PAPR) issues in channel estimation, especially with the introduction of wider bandwidths like 240 MHz and 320 MHz in the next-generation IEEE 802.11be standard.
Innovation Solution
Designing a low-PAPR long training field (LTF) sequence for physical layer protocol data units (PPDUs) that considers PAPR on single and combined resource units, as well as multi-stream scenarios, by employing operations such as negation and reversing sequences, to ensure accurate channel estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional LTF sequence is used for channel estimation in IEEE 802.11ax standard, then channel estimation can be performed, but the PAPR becomes high which degrades system performance
Solution Approach 1:
The patent applies parameter changes by transforming the conventional LTF sequence through specific operations (negating elements, reversing sequences) to modify its PAPR characteristics. The method generates multiple candidate LTF sequences by applying different transformation parameters to the base sequence, then selects the sequence with optimal PAPR performance for each bandwidth scenario.
Solution Approach 2:
The patent implements dynamics by adapting the LTF sequence design to different bandwidth conditions (80 MHz, 160 MHz, 240 MHz, 320 MHz). The sequence transformation operations are dynamically adjusted based on the operating bandwidth, allowing the system to maintain low PAPR across various bandwidth scenarios while preserving channel estimation accuracy.
2Productivity
If wider bandwidths (240 MHz, 320 MHz) are introduced in IEEE 802.11be standard, then throughput is improved, but PAPR increases which affects system performance
Solution Approach 1:
The patent applies segmentation by dividing the wide bandwidth into multiple resource units (RUs) and designing LTF sequences specifically for each RU configuration. The method considers PAPR on single RUs, combined RUs, and multi-stream scenarios separately, allowing optimized sequence design for each segment of the bandwidth while maintaining overall system throughput.
3Object-generated harmful factors
If LTF sequence is designed for specific bandwidth, then PAPR is optimized for that bandwidth, but adaptability to different bandwidths is reduced
Solution Approach 1:
The patent implements universality by creating a set of LTF sequence generation rules that can be applied across multiple bandwidth scenarios. The base sequence and transformation operations (negation, reversal) are designed to work universally, with the specific sequence selection depending on the bandwidth configuration. This allows a single set of rules to generate appropriate LTF sequences for 80 MHz, 160 MHz, 240 MHz, and 320 MHz bandwidths.
Data Source
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AI summary
This application relates to the field of wireless communication technologies, and in particular, to a method and an apparatus for transmitting a physical layer protocol data unit, and for example, is applied to a wireless local area network. The method includes: A first communications device generates a PPDU and may send the PPDU, where the PPDU includes an LTF sequence; and correspondingly, a second communications device receives the PPDU, and parses the PPDU to obtain the LTF sequence included in the PPDU. Embodiments of this application can be used to design an LTF sequence that has a relatively low PAPR on entire bandwidth, on a single resource unit, on a combined resource unit, and in a considered multi-stream scenario.