Group-Based Unequal MCS Allocation for Single User WLAN MIMO
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Solution Overview
Problem
Current wireless local area network (WLAN) technologies are limited by the constraint of using only one modulation and coding scheme (MCS) for all spatial streams in multiple input, multiple output (MIMO) transmissions, which restricts network performance and throughput, especially for single user stations in multi-user MIMO scenarios.
Innovation Solution
Implementing a method to allocate multiple unequal modulation and encoding schemes (MCSs) to a single user station by reusing user fields in packet preambles, allowing for efficient spatial stream allocation and backward compatibility with legacy devices, utilizing existing hardware resources in access points and stations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If only one MCS is applied to all spatial streams for a single user station, then device complexity is reduced and compatibility is maintained, but network performance and throughput are limited
Solution Approach 1:
The patent segments the spatial streams into multiple groups, with each group assigned a different MCS. This allows the system to apply multiple MCSs to a single user station by dividing the transmission streams into distinct segments, each handled with appropriate modulation and coding parameters, thereby improving throughput without requiring complete redesign of the transmission framework
Solution Approach 2:
The patent enables existing MU-MIMO user field structures to serve dual purposes: maintaining backward compatibility with legacy single-MCS systems while simultaneously supporting advanced multi-MCS allocations for enhanced performance. The same packet preamble structures are universally used for both legacy and advanced transmission modes
2Productivity
If multiple MCSs are allocated to a single user station, then spatial usage efficiency is enhanced, but compatibility with legacy systems deteriorates
Solution Approach 1:
The patent applies different MCSs to different groups of spatial streams based on local channel conditions and user requirements. Each spatial stream group can be optimized independently with appropriate modulation and coding parameters, allowing high-performance multi-MCS transmission for capable devices while maintaining standard single-MCS operation for legacy devices
Solution Approach 2:
The patent reuses the existing MU-MIMO user field packet preamble structures to convey multi-MCS allocation information. By copying and adapting the established packet format to carry additional MCS indication fields, the system achieves multi-MCS functionality without creating entirely new protocol structures, thus maintaining compatibility with legacy packet processing
3Adaptability or versatility
If multiple encoders and decoders are built into AP and station products, then support for MU-MIMO and multiple MCSs is enabled, but device complexity and cost increase
Solution Approach 1:
The patent merges the functionality of multiple encoders and decoders into shared hardware resources that can be dynamically allocated. By combining encoding/decoding resources into pools that can serve multiple spatial streams and multiple users, the system achieves MU-MIMO and multi-MCS capability without requiring separate dedicated hardware for each function, thereby reducing overall device complexity and cost
Data Source
Figure 1A
Figure 1B~1C
Figure 1D
AI summary
Systems and methods of transmitting a PPDU to or from a single user station (STA) in an MIMO transmission by using unequal MCSs. An access point (AP) allocates a plurality of spatial streams to the STA and assigned them into groups for the MIMO transmission. Multiple unequal MCSs are assigned to the different spatial stream groups. Correspondingly the STA ID is repeatedly specified in the user block fields of a SIG-B field of a downlink PPDU, or in the user information fields of a trigger frame. Alternatively, multiple AIDs of the STA can be specified in the user block fields or the user information fields instead of repeating the same STA ID. An indication may be inserted in the SIG-A field to indicate that the grouped-based unequal MCSs scheme is used for the MIMO transmission.