WLAN Frame Guard Subcarrier Allocation for Legacy Compatibility
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Solution Overview
Problem
Existing WLAN technologies face challenges in providing additional signaling information while maintaining backward compatibility with legacy systems, which is essential for enhancing system throughput in high-density scenarios.
Innovation Solution
The method involves allocating predetermined information to additional data subcarriers in the legacy short training field, legacy long training field, legacy signal field, and data field of a legacy frame format, allowing for the transmission and reception of frames that include this additional information, using a processor and transceiver in a WLAN device to manage these fields and subcarriers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If additional signaling information is provided in the WLAN frame, then the system throughput in high-density scenarios is enhanced, but the compatibility with legacy WLAN standards deteriorates
Solution Approach 1:
The patent embeds additional signaling information within the existing legacy frame structure by utilizing guard subcarriers that are already present in the OFDM signal. The new information is nested inside the traditional frame format without altering the outer structure, allowing legacy devices to ignore the embedded information while newer devices can extract and utilize it for improved throughput in high-density scenarios.
Solution Approach 2:
The patent applies different qualities to different parts of the frame structure. Specifically, certain subcarriers (guard subcarriers at specific positions) are repurposed to carry additional signaling information, while the rest of the frame maintains its original legacy format. This localized modification allows new functionality to be added without affecting the overall compatibility of the frame structure with legacy standards.
2Loss of information
If the frame structure is modified to include additional information fields, then more signaling information can be transmitted, but the complexity of the frame structure increases
Solution Approach 1:
The patent makes the existing guard subcarriers serve multiple functions: they continue to provide their original purpose as guard bands for spectral separation while simultaneously carrying additional signaling information. This multi-functionality approach allows the system to transmit more information without adding new structural elements, thereby avoiding increased frame structure complexity while improving signaling information completeness.
3Quantity of substance
If guard subcarriers are reused to carry additional data, then frequency resource utilization is improved, but the reliability of the legacy frame format deteriorates
Solution Approach 1:
The patent segments the guard subcarriers into distinct functional zones within the frequency spectrum. Specific subcarriers at defined positions (e.g., subcarriers -28, -27, 27, 28 in a 64-subcarrier OFDM signal) are allocated for carrying additional signaling information, while other guard subcarriers maintain their traditional protective function. This segmentation allows the system to improve frequency resource utilization without compromising the reliability of the legacy frame format, as the protective guard subcarriers remain intact.
Data Source
AI summary
A method of transmitting a frame is provided by a device in a WLAN. The device sets as additional data subcarriers some of subcarriers which are not set as data subcarriers in at least part of fields included in a frame of a legacy frame format, and allocates information to the additional data subcarriers.