Uplink Interference Alignment via Piggybacked Beamforming
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Solution Overview
Problem
Current Wi-Fi uplink transmissions from multiple stations to an access point occur sequentially, limiting throughput and the need for concurrent transmissions to enhance communication efficiency.
Innovation Solution
Implementing an Interference Alignment (IA) scheme with a new Long Training field (LTF) design for the uplink frame format and a modified downlink/uplink protocol that piggybacks beamforming information on downlink data to enable simultaneous uplink transmissions from multiple stations, using channel estimation and beamforming reports to align interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sequential uplink transmissions are used, then interference management is simplified, but uplink throughput is limited
Solution Approach 1:
The patent changes the transmission parameters by introducing beamforming vectors and interference alignment coefficients. Each STA adjusts its transmission parameters based on channel state information and interference alignment requirements, enabling concurrent transmissions while managing interference through parameter optimization rather than sequential access
Solution Approach 2:
The AP performs preliminary channel estimation and computes beamforming information before the actual uplink transmissions. This preliminary action includes obtaining channel state information from downlink transmissions, calculating interference alignment parameters, and distributing beamforming feedback to STAs in advance, so that when concurrent transmissions occur, the interference alignment is already configured
2Productivity
If concurrent uplink transmissions are enabled, then uplink throughput is improved, but interference alignment computation complexity increases
Solution Approach 1:
The patent segments the interference alignment computation into two parts: the AP performs channel estimation and computes overall beamforming strategies based on global channel state information, while each STA independently computes its specific beamforming vector based on received feedback and local channel conditions. This segmentation distributes the computational burden and enables scalable implementation
Solution Approach 2:
The AP acts as an intermediary that collects channel state information from all STAs, computes the interference alignment parameters, and distributes beamforming feedback to each STA. This intermediary role simplifies the overall system architecture by centralizing the complex interference management computations at the AP, which has more processing capability, while STAs only need to implement the prescribed beamforming based on feedback
3Loss of substance
If beamforming information is piggybacked on downlink data, then overhead is reduced, but downlink data throughput is affected
Solution Approach 1:
The patent merges the beamforming feedback information with downlink data transmissions by piggybacking the beamforming vectors on downlink frames. Instead of separate feedback channels, the beamforming information is combined with regular downlink data transmissions, utilizing the existing downlink resource to carry dual-purpose information (data and beamforming control)
Solution Approach 2:
The downlink transmission serves multiple functions simultaneously: it delivers data to STAs and carries beamforming feedback information for uplink interference alignment. This multi-functionality reduces the need for dedicated feedback channels and minimizes protocol overhead while maintaining efficient resource utilization
Data Source
AI summary
Embodiments are provided to enable concurrent uplink transmissions from multiple Wi-Fi stations (STAs) to one or more access points (APs) using Interference Alignment (IA). In an embodiment, the STAs broadcast, to one or more APs, beamforming reports including channel estimation information for downlink. The one or more AP then performs channel estimation using the beamforming reports, and selects at least some of the STAs. The AP also computes beamforming information for IA of uplink transmissions between the selected STAs and sends, to the selected STAs, the beamforming information. The beamforming information is piggy-backed over downlink data packets to the selected STAs. Each selected STA then sends an uplink data frame concurrently with one or more other uplink data frames from one or more other selected STAs to the AP. The uplink data frames are configured for concurrent uplink transmissions according to the beamforming information for IA.