UL MU MIMO MAC Signaling for Network Capacity
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Solution Overview
Problem
Existing UL MU MIMO systems face challenges in differentiating signals from multiple STAs due to the need for orthogonal long training fields (LTFs) and determining appropriate modulation coding schemes (MCS) for efficient network capacity enhancement.
Innovation Solution
Implementing medium access control (MAC) signaling to notify STAs about multicast addresses, total streams, individual MCS, and P matrix rows, along with UL MU MIMO Group frames that include max duration and association IDs, enabling coordinated transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple STAs transmit simultaneously using UL MU MIMO, then network capacity increases, but signal differentiation becomes more difficult requiring orthogonal LTFs
Solution Approach 1:
The patent segments the network capacity enhancement into multiple orthogonal LTFs, where each STA is assigned a unique orthogonal sequence. This segmentation allows simultaneous transmissions to be separated at the receiver through correlation processing, resolving the signal differentiation difficulty while maintaining high network capacity.
Solution Approach 2:
The patent changes the parameter of LTF sequences by assigning different orthogonal codes (e.g., Walsh-Hadamard sequences) to different STAs. This parameter change in the signal domain enables the AP to differentiate between multiple simultaneous uplink transmissions without increasing time or frequency resources, thus increasing network capacity while managing differentiation complexity.
2Measurement precision
If orthogonal LTFs are used for channel estimation, then signal differentiation improves, but preamble structure becomes more complex
Solution Approach 1:
The patent employs universal orthogonal sequences (such as Walsh-Hadamard codes) that serve multiple functions: they provide channel estimation, enable signal differentiation, and maintain constant amplitude. This multi-functionality achieves accurate channel estimation for multiple STAs without significantly increasing preamble complexity, as the same orthogonal code structure serves all STAs simultaneously.
3Productivity
If MAC signaling is implemented for notifying STAs about multicast addresses and MCS, then resource allocation efficiency improves, but overhead increases
Solution Approach 1:
The patent merges multiple signaling functions into a single MAC signaling message. The action frame simultaneously conveys multicast address information, MCS assignments, and resource allocation details for multiple STAs. This consolidation reduces the number of separate signaling exchanges required, improving resource allocation efficiency while minimizing the total overhead compared to individual signaling messages for each parameter.
Data Source
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Figure 3
AI summary
An embodiment of the present invention provides a wireless station (STA), comprising a transceiver operable for communicating in a wireless network, wherein the transceiver is adapted for Uplink MultiUser Multiple Input Multiple Output (UL MU MIMO) Medium Access Control (MAC) support.