MIMO Transmission via Analogue RF Signal Combining
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Solution Overview
Problem
Current IEEE 802.11 WLAN systems face limitations in increasing cell capacity and transmission reliability due to high hardware costs and complexity associated with existing MIMO transmission schemes, which require extensive baseband processing and multiple antennas.
Innovation Solution
A method that dynamically switches between MIMO and SISO transmission modes by using a single stream of analogue RF signals with varying amplitudes and phases, allowing for reduced hardware overhead by performing spatial processing in the analogue RF domain, thereby enabling higher reliability with lower fabrication costs and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full MIMO transmission schemes are used to improve transmission reliability and radio coverage, then transmission reliability is improved, but hardware effort and baseband processing complexity are strongly increased
Solution Approach 1:
The patent replaces digital baseband processing with analogue RF domain processing. Instead of using multiple digital baseband processing branches for MIMO transmission, the invention uses analogue signal processing in the RF domain, specifically using a single baseband processing path to handle multiple spatial streams by applying spatial processing weights to analogue RF signals from multiple antennas before they reach the baseband processor.
Solution Approach 2:
The patent extracts the spatial processing function from the digital baseband domain and places it in the analogue RF domain. By removing spatial processing weights application from the baseband processing path, the system achieves MIMO transmission reliability without requiring multiple complex baseband processing branches, thus reducing baseband processing complexity and hardware effort.
2Reliability
If multiple antennas are used for MIMO transmission to enhance cell capacity, then transmission reliability is improved, but chip area and cost are increased
Solution Approach 1:
The patent makes the single baseband processing path universal by enabling it to handle multiple spatial streams through analogue RF signal processing. The same baseband processing path processes signals from multiple antennas by applying spatial processing weights in the analogue domain, eliminating the need for separate baseband processing paths for each antenna, thus reducing chip area and manufacturing cost.
3Device complexity
If analogue RF signal combining is used to reduce baseband processing paths, then hardware overhead is reduced, but transmission reliability must be maintained
Solution Approach 1:
The patent employs feedback mechanisms through channel estimation and weight adjustment. The system estimates channel characteristics and uses this information to adaptively adjust spatial processing weights applied to analogue RF signals, ensuring that transmission reliability is maintained while using reduced baseband processing paths. The feedback loop continuously optimizes the combining algorithm based on actual channel conditions.
Data Source
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AI summary
The present invention allows an IEEE802.11 receiver to operate on two alternative physical layers. The first of the two alternative physical layers is the conventional IEEE802.11 physical layer according to a respective specific standard, which is well known in the art and provides communication between a transmitter and a receiver via a SISO OFDM transmission. A second, alternative physical layer that, among other advantages, enables a higher reliability than the conventional IEEE802.11 physical layer, is provided by operating the IEEE802.11 receiver to process a specific type of MIMO transmissions, which as such are foreign to the IEEE802.11 WLAN standards. A MIMO transmission according to the present invention has multiple concurrent transmissions of a single stream of analogue RF data signals, wherein corresponding analogue RF data signals of different ones of the concurrent transmissions of the stream differ only by having different amplitudes or different phases, or both, different amplitudes and phases.