Unequal OFDM Modulation Across Spatial Streams and Frequency Subblocks
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Solution Overview
Problem
Existing wireless local area network (WLAN) systems face inefficiencies in spectral utilization due to limitations in channel bandwidth and modulation techniques, particularly when supporting devices with varying bandwidth capabilities, leading to underutilization of available frequency resources.
Innovation Solution
Implementing unequal modulation over spatial streams and frequency segments by allocating specific modulation orders and resource units to optimize data transmission across multiple spatial streams and frequency subblocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single channel bandwidth is used for all devices in the BSS, then compatibility and ease of operation are improved, but spectral efficiency and resource utilization deteriorate because devices with different bandwidth capabilities cannot utilize optimal frequency resources
Solution Approach 1:
The patent segments the frequency spectrum into multiple channels of different bandwidths (20 MHz, 40 MHz, 80 MHz, 160 MHz) that can be simultaneously utilized by different devices based on their capabilities. This allows the BSS to divide frequency resources into manageable segments that match various device requirements, resolving the contradiction between maintaining operational simplicity and achieving high spectral efficiency.
Solution Approach 2:
The patent introduces an additional dimension of frequency bandwidth selection beyond the traditional single-channel approach. By enabling devices to operate across multiple frequency dimensions (different channel widths) simultaneously, the system achieves both compatibility for legacy devices and optimized performance for capable devices, thereby resolving the trade-off between ease of operation and spectral efficiency.
2Ease of operation
If equal modulation is applied to all spatial streams, then device compatibility and ease of operation are improved, but throughput and spectral efficiency deteriorate because devices with varying capabilities cannot achieve optimal data rates
Solution Approach 1:
The patent applies local quality by allowing different modulation schemes (BPSK, QPSK, 16-QAM, 64-QAM, 256-QAM, 1024-QAM) to be applied to different spatial streams based on local channel conditions and device capabilities. This enables each spatial stream to use the most appropriate modulation level for its specific context, thereby achieving both compatibility and optimized throughput without requiring uniform modulation across all streams.
Solution Approach 2:
The patent introduces dynamic modulation adaptation where the modulation order for each spatial stream can be dynamically adjusted based on real-time channel quality indicators and device capabilities. This dynamic approach allows the system to maintain compatibility with various device types while simultaneously optimizing throughput by selecting higher modulation orders for streams with better channel conditions.
3Productivity
If contiguous frequency channels are combined to increase bandwidth, then throughput is improved, but frequency resource flexibility and adaptability to diverse device capabilities deteriorate
Solution Approach 1:
The patent segments wide frequency bands into smaller, independently configurable channel units (20 MHz, 40 MHz, 80 MHz, 160 MHz) that can be selectively combined. This segmentation allows the system to achieve high throughput by combining channels when needed while maintaining the flexibility to use smaller channel units for devices with limited capabilities, thereby resolving the contradiction between throughput enhancement and frequency resource adaptability.
Solution Approach 2:
The patent creates a universal frequency resource framework where the same physical spectrum can serve multiple functions simultaneously - supporting both wide-channel high-throughput operations and narrow-channel legacy device operations. This multi-functionality allows the system to adapt frequency resources to diverse device capabilities while maintaining the option to achieve high throughput through channel aggregation when appropriate.
Data Source
AI summary
Methods and procedures are disclosed herein for applying unequal modulation over spatial streams and/or frequency segments. A STA may determine, for each spatial stream of a plurality of spatial streams, a plurality of frequency subblocks, each frequency subblock including one or more respective resource units (RUs) and an associated modulation order, and each RU including a respective number of occupied data tones. The STA may parse a bit sequence corresponding to an OFDM symbol into the plurality of spatial streams. For each spatial stream, the STA may allocate, for each frequency subblock, a respective number of consecutive bits of the OFDM symbol that corresponds to the associated modulation order of the frequency subblock and the respective number of occupied data tones in the RUs of the frequency subblock. The STA may transmit the plurality of spatial streams according to the allocation over the occupied data tones.