DL MU PPDU Structure for Uplink Resource Allocation
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing uplink/downlink multi-user data transmission and reception, particularly in dense environments with many access points and stations, leading to issues like power imbalance and increased overhead in existing WLAN systems.
Innovation Solution
The proposed solution involves generating and transmitting a downlink (DL) multi-user physical protocol data unit (PPDU) with resource allocation information for uplink (UL) MU transmission, including a first part with a specific inverse discrete Fourier transform (IDFT)/discrete Fourier transform (DFT) period and a second part with a four times longer period, allowing for efficient resource allocation and reduced overhead through duplication across multiple channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing WLAN systems are used in dense environments with many access points and stations, then basic data transmission is supported, but power imbalance occurs across bands and overhead increases
Solution Approach 1:
The PPDU structure is segmented into distinct parts: a first part with a specific IDFT/DFT period for legacy compatibility and a second part with a four times longer period for enhanced multi-user transmission. This segmentation allows the system to maintain compatibility with existing devices while introducing new capabilities, thereby reducing overhead for legacy devices and improving reliability for multi-user scenarios.
Solution Approach 2:
The patent introduces a new dimension in the frequency domain by utilizing a four times longer IDFT/DFT period in the second part of the PPDU. This dimensional change enables more efficient resource allocation across multiple bands and channels, preventing power imbalance and reducing collisions in dense environments without increasing overall system overhead.
2Productivity
If resource allocation is optimized for multi-user transmission, then spectrum efficiency improves, but power imbalance across bands occurs
Solution Approach 1:
The patent applies local quality by allocating different IDFT/DFT periods to different parts of the transmission: the first part uses a standard period for legacy compatibility, while the second part uses a four times longer period for optimized multi-user transmission. This local differentiation allows spectrum efficiency to be improved in the second part without causing power imbalance in the first part, as each part is optimized for its specific function.
3Productivity
If channels are fully utilized for data transmission, then throughput increases, but empty channels remain causing collisions
Solution Approach 1:
The patent implements preliminary action by including a first part in the PPDU that performs channel assessment and protection functions before the main data transmission in the second part. This first part with the standard IDFT/DFT period prepares the channel and provides TXOP protection, ensuring that subsequent transmissions in the second part occur without collisions, thereby maintaining high throughput while improving collision resistance.
Data Source
AI summary
An AP downlink multi-user transmission method in a wireless communication system, according to one embodiment of the present invention, comprises the steps of: generating a DL MU PPDU, wherein the DL MU PPDU comprises resource allocation information for uplink MU transmission by a station (STA); transmitting the DL MU PPDU to the STA; and, on the basis of the DL MU PPDU, receiving a UL MU PPDU generated by the STA, wherein the UL MU PPDU comprises a first part having a first IDFT/DFT cycle, and a second part having a second IDFT/DFT cycle that is four times the first IDFT/DFT cycle, wherein the first part may be received through at least one 20 MHz channel in a position corresponding to a frequency resource indicated by the resource allocation information, and the second part may be received by using the frequency resource indicated by the resource allocation information.