DRU OFDM Long Training Field Truncation for 2×-LTF Transmission
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless communication systems like IEEE 802.11 series, the lack of long training field (LTF) arrangement for distributive resource unit (DRU) transmission in trigger-based physical layer protocol data units (PPDU) prevents the application of 2×-LTF sequences, especially in highly efficient (HE) or extremely high throughput (EHT) systems.
Innovation Solution
Generate a reduced-length LTF by truncating a subset of time-domain samples and transmit a packet with a 2×-LTF corresponding to DRU tones, utilizing a 4×-LTF sequence to align with DRU tone plans, reducing LTF overhead without defining a separate 2×-LTF sequence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a 4×-LTF sequence is applied to DRU tones, then the LTF can be aligned with DRU tone plans, but the LTF symbol size becomes too large and cannot be transmitted efficiently
Solution Approach 1:
The patent segments the 4×-LTF sequence into two halves by removing repeated time-domain samples. Specifically, after generating the 4×-LTF sequence and performing IDFT, the time-domain samples are divided into repeated sets, and only one set is retained to form the 2×-LTF sequence. This segmentation reduces the LTF symbol size by half while maintaining alignment with DRU tone plans.
Solution Approach 2:
The patent extracts only the necessary portion of the 4×-LTF sequence by removing repeated samples. The 4×-LTF sequence is generated first, then the repeated time-domain samples are identified and removed, extracting only the unique sample sets needed for the 2×-LTF transmission. This extraction reduces overhead while preserving the essential LTF functionality.
2Device complexity
If no LTF arrangement is defined for DRU transmission, then the tone plan can be simplified, but the 2×-LTF sequence cannot be applied as defined in HE or EHT systems
Solution Approach 1:
The patent makes the 4×-LTF sequence serve multiple functions: it first serves as the basis for generating the 2×-LTF sequence through sample removal, and then the resulting 2×-LTF sequence is applied to DRU tones. This universal approach allows the same sequence generation process to serve both HE and EHT system requirements while adapting to DRU tone plans.
Solution Approach 2:
The patent changes the parameter of LTF sequence length from 4× to 2× by modifying the time-domain sample count. The 4×-LTF sequence is transformed into a 2×-LTF sequence by removing repeated samples, effectively changing the length parameter while maintaining the sequence's utility for DRU transmission in HE and EHT systems.
3Productivity
If the 2×-LTF sequence is applied to DRU tones, then communication efficiency is enhanced, but the LTF overhead must be reduced
Solution Approach 1:
The patent applies partial action by using only half of the original 4×-LTF sequence (the 2×-LTF sequence) for DRU transmission. Instead of transmitting the full 4× sequence, only the necessary 2× sequence is transmitted, reducing overhead by 50% while maintaining sufficient LTF functionality for channel estimation and synchronization in HE and EHT systems.
Data Source
AI summary
A communication method has the step of: generating time-domain samples of an orthogonal frequency-division multiplexing (OFDM) symbol, the time-domain samples comprising a plurality of sets of samples, each of the plurality of sets of samples being same as another one of the plurality of sets of samples or being obtainable based on the another one of the plurality of sets of samples by using one or more operations including negating, complex conjugate, or a combination thereof; and transmitting a packet comprising a portion of the time-domain samples of the OFDM symbol, the portion of the time-domain samples comprising one or more selected sets of samples selected from the plurality of sets of samples in accordance with a ratio.