Unequal MCS Assignment Across Spatial Streams in WLAN
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Solution Overview
Problem
Current MCS assignment methods in wireless local area networks (WLAN) are suboptimal due to SNR imbalance across spatial streams, leading to reduced throughput and reliability, as they assign the same MCS index to all spatial streams based on the worst stream, neglecting variations in channel quality.
Innovation Solution
The proposed method determines a maximum difference in MCS indices across spatial streams, identifies a primary spatial stream based on the type of unequal MCS, and assigns unique MCS indices to each stream, considering the best, median, or worst SNR to optimize channel conditions and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same MCS index is assigned to all spatial streams based on the worst stream, then the system maintains simplicity in MCS assignment, but throughput and reliability are reduced due to SNR imbalance across spatial streams
Solution Approach 1:
The patent segments the MCS assignment process by identifying a primary spatial stream and assigning different MCS indices to different spatial streams. Specifically, the AP determines a primary spatial stream from multiple spatial streams and assigns a first MCS index to the primary stream and a second MCS index to non-primary streams, allowing differentiated treatment of streams based on their channel conditions.
Solution Approach 2:
The patent applies local quality by making the MCS index assignment dependent on the specific spatial stream's characteristics. The primary spatial stream receives a different MCS index than non-primary streams, optimizing each stream's transmission parameters according to its local channel quality and importance.
2Reliability
If the same MCS index is assigned to all spatial streams based on the worst stream, then the system ensures uniform protection across streams, but channel utilization and performance are suboptimal due to neglecting variations in channel quality
Solution Approach 1:
The patent introduces dynamics by making the MCS assignment adaptive rather than static. The system dynamically identifies a primary spatial stream and assigns different MCS indices based on real-time channel conditions and stream importance, allowing the system to adapt to varying SNR conditions across different spatial streams.
Solution Approach 2:
The patent changes the MCS index parameter differently for primary and non-primary spatial streams. By assigning a first MCS index to the primary stream and a second MCS index to non-primary streams, the system optimizes transmission parameters according to each stream's channel quality and importance, improving both reliability and channel utilization.
3Productivity
If unequal MCS indices are assigned to different spatial streams, then throughput and reliability are enhanced by adapting to varying SNR conditions, but the complexity of MCS assignment increases
Solution Approach 1:
The patent applies preliminary action by having the AP determine and identify the primary spatial stream before MCS index assignment. This preliminary identification of the primary stream based on channel conditions and importance allows the system to systematically assign different MCS indices, reducing the complexity that would otherwise arise from ad-hoc decisions.
Solution Approach 2:
The system uses feedback mechanisms to determine the primary spatial stream based on channel conditions. The AP receives channel quality information and uses this feedback to identify which spatial stream should be primary, enabling informed MCS assignment that balances throughput enhancement with manageable complexity.
4Reliability
If the MCS index is assigned based on the worst spatial stream, then the system ensures acceptable error rates across all streams, but the overall throughput is limited by the weakest stream
Solution Approach 1:
The patent segments the spatial streams into primary and non-primary categories, allowing different error rate control strategies for different streams. The primary stream receives optimized MCS indexing that balances reliability and throughput, while non-primary streams receive appropriate MCS indices that maintain acceptable error rates without unnecessarily limiting throughput.
Solution Approach 2:
The patent changes the MCS index parameter assignment strategy by using different indices for primary and non-primary spatial streams. This allows the system to optimize the primary stream for higher throughput while maintaining acceptable error rates, rather than being constrained by the worst stream's conditions across all streams.
Data Source
AI summary
Embodiments disclose methods for assigning an unequal modulation and coding scheme (MCS) in a wireless network by a user equipment (UE). The method includes determining a maximum difference in an MCS index allowed across different spatial streams per user and determining a type of unequal MCS enabled at the UE. The method includes identifying a primary spatial stream, based on the type of unequal MCS enabled at the UE. Further, the method includes enabling assignment of the at least one MCS index to all the spatial streams based on at least one of the maximum difference in the MCS index allowed across different spatial streams per user, the type of unequal MCS enabled at the UE, or the identification of the primary spatial stream.