DRU Long Training Field Reconstruction for 2×-LTF Wi-Fi Transmission
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Solution Overview
Problem
Existing wireless communication systems, such as IEEE 802.11 series, lack a method to apply 2×-long training fields (LTF) for distributed resource unit (DRU) transmission due to non-aligned LTF arrangements, which is necessary for high efficiency (HE) and extremely high throughput (EHT) systems.
Innovation Solution
A method is introduced to receive a reduced-length LTF, perform arithmetic operations to obtain a complete LTF, and append amended reduced-length LTFs to achieve 2×-LTF transmission by aligning LTF sequences with DRU tone plans, including specific DRU tone plans for 20 MHz and 40 MHz bandwidths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the traditional LTF arrangement is used for DRU transmission, then the LTF can be occupied only to the subcarriers overlapped with the scheduled resource unit, but the 2×-LTF sequence cannot be assigned to the tones where the DRU is scheduled, making it impossible to apply the 2×-LTF sequence as defined in HE or EHT systems
Solution Approach 1:
The LTF is segmented into multiple parts: a reduced-length LTF that fits within the DRU tone structure, and additional LTF sequences that are appended through arithmetic operations. This segmentation allows the LTF to be adapted to the DRU tone plan while maintaining the 2×-LTF structure through concatenation of segments.
Solution Approach 2:
The solution transitions from a frequency-domain arrangement problem to a time-domain solution by appending LTF sequences. The arithmetic operations on the reduced-length LTF generate additional sequences that are concatenated in the time domain, effectively solving the tone alignment issue through dimensional transformation.
2Manufacturing precision
If the LTF is occupied only to the subcarriers overlapped with the scheduled resource unit, then the LTF arrangement follows the DRU tone plan, but the complete LTF cannot be obtained without additional processing
Solution Approach 1:
The reduced-length LTF is first arranged precisely according to the DRU tone plan in the frequency domain. Then, arithmetic operations are performed in advance to generate the complete LTF structure, ensuring both precise arrangement and complete formation before transmission.
Solution Approach 2:
The reduced-length LTF serves as an intermediary between the DRU tone plan constraints and the complete 2×-LTF structure. Through arithmetic operations, this intermediate form is transformed into the complete LTF, bridging the gap between the constrained tone arrangement and the desired full LTF structure.
3Reliability
If a reduced-length LTF is used to fit the DRU tone structure, then the LTF can be aligned with DRU tones, but the LTF symbol size is reduced and needs to be extended to maintain performance
Solution Approach 1:
Multiple reduced-length LTF sequences are merged through arithmetic operations and concatenation to form the complete LTF. This combining process extends the effective LTF length while maintaining alignment with the DRU tone structure, ensuring both reliability and appropriate symbol length.
Solution Approach 2:
The LTF parameters are changed from a single continuous sequence to a structured concatenation of processed segments. The arithmetic operations transform the reduced-length LTF parameters to generate additional sequences, effectively changing the length parameter while maintaining the essential characteristics needed for reliable channel estimation.
Data Source
AI summary
A communication method including receiving a packet including a reduced-length long training field (LTF) corresponding to a set of distributed resource units (DRU) tones. The method further includes, based at least in part on a DRU tone plan, performing one or more arithmetic operations on the reduced-length LTF in order to obtain a complete LTF associated with the reduced length LTF. In some embodiments, there is provided a DRU tone plan for 40 MHz DBW. The DRU tone plan includes: eighteen 26-tone DRUs with eighteen tone spacing between the tones; eight 52-tone DRUs, built from two DRU26, with eight or ten tone spacing between the tones; four 106-tone DRUs, built from four DRU26 or two DRU52 and 2 extra padding tones, with four or six tone spacing between the tones; and two 242-tone DRUs, built from two DRU106 and one DRU26 and 4 extra padding tones, with two tone spacing between the tones.