OFDMA RU Tone Distribution Under PSD-Limited Wi‑Fi PPDU
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Solution Overview
Problem
Wireless communication systems face limitations in transmitter power due to government-regulated power spectral density (PSD) requirements, restricting the use of orthogonal frequency division multiple access (OFDMA) resource units (RUs) in IEEE 802.11ax systems.
Innovation Solution
The method involves determining resource units (RUs) with specific tone distributions to allocate null and guard subcarriers, allowing for increased per-tone transmit power and improved data transmission performance by optimizing the distribution of subcarriers within the physical layer protocol data unit (PPDU).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional OFDMA resource units are used with standard tone distribution, then the system can operate with simple resource allocation, but the per-tone transmit power is limited and data transmission performance is reduced due to PSD regulations
Solution Approach 1:
The patent segments the resource units into different types (first RUs and second RUs) with different tone distribution patterns. The first RUs use a first tone distribution pattern while second RUs use a second tone distribution pattern, allowing selective optimization of per-tone power for different user requirements without requiring complete system redesign
Solution Approach 2:
The patent dynamically selects between different tone distribution patterns based on user requirements and channel conditions. The system can flexibly switch between first and second tone distribution patterns for different RUs within the same PPDU, enabling adaptive power optimization rather than static allocation
2Reliability
If distributed resource units with optimized tone distribution are used, then data transmission performance is improved through increased per-tone power, but the complexity of determining and managing tone distributions increases
Solution Approach 1:
The patent pre-defines multiple tone distribution patterns (first and second patterns) before the actual data transmission. These patterns are prepared in advance and can be directly applied to different RUs without requiring real-time complex calculations, reducing the computational burden during transmission
Solution Approach 2:
The patent changes the tone distribution parameters (which tones are allocated to which RUs) to optimize power distribution. By adjusting these parameters systematically across different RU types, the system achieves improved transmission performance while maintaining manageable complexity through structured parameter management
3Productivity
If null subcarriers are allocated between consecutive RUs in conventional systems, then the system maintains simple allocation rules, but the efficient use of spectrum and power is reduced
Solution Approach 1:
The patent applies different null subcarrier allocation rules to different RU types. For first RUs, null subcarriers are allocated between consecutive RUs, while for second RUs, null subcarriers are allocated differently based on their specific tone distribution pattern. This localized optimization maximizes spectrum efficiency without requiring complete rule redesign
Solution Approach 2:
The patent introduces a new dimension to the allocation problem by considering both RU type and tone distribution pattern simultaneously. Instead of a single uniform allocation rule, the system evaluates multiple dimensions (RU index, tone pattern, channel conditions) to determine optimal null subcarrier placement, achieving higher efficiency through multi-dimensional optimization
Data Source
AI summary
A communication method includes: determining a plurality of resource units (RUs) of a physical layer protocol data unit (PPDU) with a first bandwidth; and transmitting a signal to a device using one or more RUs of the plurality of RUs. Locations of the plurality of RUs are determined based on a first-level tone distribution and a second-level tone distribution; the first-level tone distribution is used to indicate a mapping relationship between distributed subcarrier indices of 26-tone RU, 52-tone RU and 106-tone RU and subcarrier indices of 242-tone RU in each 20 MHz subchannel, the second-level tone distribution is used to indicate a distribution of subcarrier indices of 242-tone RU in the PPDU with the first bandwidth, all null subcarriers in a 20 MHz subchannel are allocated exclusively in left and right bands, with no null subcarrier allocated between any consecutive RUs in a 20 MHz subchannel.