Resource Unit Detection in High-Efficiency Wireless Systems
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Solution Overview
Problem
In high-efficiency wireless systems, such as those operating under the IEEE 802.11ax standard, it is challenging to accurately identify active resource units as not all stations respond to the trigger frame, leading to inefficient resource allocation and potential power wastage due to unoccupied resource units.
Innovation Solution
The method involves quantizing phase angle samples from the short training field, performing a transform operation to derive transmitted power, and comparing it to other resource units to identify active or inactive units based on predetermined relationships, thereby determining which resource units to activate or deactivate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If trigger frame is sent to solicit station responses for resource allocation, then bandwidth resource units can be allocated, but not all stations respond leading to inaccurate identification of active resource units
Solution Approach 1:
The patent replaces the mechanical/response-based detection method with an electromagnetic signal-based detection method. Instead of relying on stations to respond to trigger frames and manually report their status, the system uses HE-LTF (High-Efficiency Long Training Field) signals transmitted across all resource units to passively detect which units are actually active through electromagnetic signal analysis, eliminating the dependency on station responses.
Solution Approach 2:
The system makes the resource units self-revealing through their own transmitted signals. Active resource units automatically expose their presence and power levels through the HE-LTF signals they transmit, allowing the access point to detect active units without requiring them to actively report or respond to queries. This self-service detection mechanism ensures accurate identification regardless of whether stations respond to trigger frames.
2Measurement precision
If all resource units are monitored to identify active ones, then accurate resource allocation is achieved, but power consumption increases due to unnecessary monitoring of inactive units
Solution Approach 1:
The patent applies partial action by transmitting HE-LTF signals only across the frequency spectrum ranges corresponding to allocated resource units rather than monitoring the entire bandwidth. The access point calculates expected power levels for each resource unit based on its allocation and only performs detailed power comparison for units that show signals above the threshold, avoiding unnecessary monitoring of inactive units across the full spectrum.
Solution Approach 2:
The system changes the detection parameter from binary presence/absence detection to power-level-based detection. By measuring the actual power level of HE-LTF signals and comparing them against expected values derived from resource unit allocations, the system can distinguish between actively transmitting units and inactive ones, enabling selective monitoring that reduces power consumption while maintaining accuracy.
3Productivity
If resource units are allocated based on trigger frame responses, then bandwidth allocation is established, but unoccupied resource units cause power wastage
Solution Approach 1:
The patent implements feedback by measuring the actual power levels of HE-LTF signals received from each resource unit and using this information to verify whether units are actually occupied. The access point compares measured power levels against expected values and feeds back this information to adjust the active resource unit list, ensuring that only truly occupied units are allocated bandwidth, thereby eliminating power wastage on unoccupied units.
Solution Approach 2:
The system performs preliminary detection of active resource units by measuring HE-LTF signal power levels before finalizing bandwidth allocation. This preliminary action identifies which units are actually in use, allowing the access point to pre-filter the list of candidate units for allocation, ensuring that bandwidth is assigned only to units that will be actively utilized, thus preventing power wastage on unoccupied units.
Data Source
AI summary
A method for identifying active resource units in a high-efficiency wireless system includes quantizing phase angles of samples received in a high-efficiency short training field of a transmission, performing a transform operation on quantized phase angle samples to derive transmitted power, comparing transmitted power of an individual resource unit as determined from transformed quantized phase angle samples to transmitted power of other resource units as determined from transformed quantized phase angle samples, and identifying, as active, resource units whose transmitted power, as determined from transformed quantized phase angle samples, bears a first predetermined relationship to transmitted power of the other resource units. Transmitted power of a resource unit may be compared to the total transmitted power of all resource units, or to the transmitted power of one of the other resource units whose transmitted power is a maximum transmitted power of all resource units. A receiver may implement the method.