Co-prime Array Asymmetric Massive MIMO Channel Estimation
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Solution Overview
Problem
The asymmetric massive MIMO channel estimation method faces challenges in maintaining accurate and reliable downlink channel information due to differences in the number of uplink and downlink antennas, leading to angular resolution issues and compromised communication performance.
Innovation Solution
An asymmetric massive MIMO channel estimation method based on a co-prime array is developed, where the base station uses a co-prime array to select uplink receiving antennas, estimate uplink channel information, and reconstruct a complete downlink channel using least absolute shrinkage and selection operator-based compressive sensing, ensuring accurate channel information for pre-coding in the time division duplex mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only part of antennas are used for receiving signals during uplink communication, then hardware cost and data processing burden are reduced, but angular resolution difference is caused making downlink channel information unreliable
Solution Approach 1:
The patent creates a virtual uplink array by copying and rearranging received signals from the partial receiving antennas through autocorrelation processing. This virtual array has the same number of elements as the full downlink array, allowing accurate channel estimation without requiring all antennas to be physically active for reception
Solution Approach 2:
The patent introduces a virtual array as an intermediary between the partial receiving antennas and the downlink channel estimation. The virtual array manifold matrix serves as a bridge that connects the limited receiving antennas to the complete downlink channel information through mathematical transformation
2Adaptability or versatility
If the number of uplink antennas is different from the number of downlink antennas, then asymmetric receiving and transmitting architecture is achieved, but difference in angular resolution is caused
Solution Approach 1:
The patent changes the parameter of array configuration by creating a virtual array with M elements from N physical receiving antennas. The virtual array manifold matrix uses the same steering vectors as the downlink array, ensuring consistent angular resolution characteristics across uplink and downlink operations
Solution Approach 2:
The patent embraces the asymmetric architecture by designing the system to work with different numbers of transmitting and receiving antennas. The virtual array construction specifically addresses the asymmetry by creating a mathematical representation that matches the downlink array configuration
3Productivity
If all antennas are used for transmitting signals during downlink communication, then communication rate is maximized, but uplink receiving pressure increases when using full-digital architecture
Solution Approach 1:
The patent applies partial action by using only N receiving antennas out of M total antennas for uplink reception. This partial configuration is sufficient to capture the necessary channel information through virtual array processing, reducing the burden on uplink receiving hardware and processing
Data Source
AI summary
A downlink channel estimation method based on a co-prime array in asymmetric massive MIMO architecture is provided. First, an uplink and downlink asymmetric receiving and transmitting system model based on a co-prime array is established, and a deviation of the frequency domain direction caused by array broadband signals is observed; then, uplink receiving is performed to estimate an uplink channel, and channel parameters such as the number of paths, the angle of arrival and the path gain are recovered; and finally, a downlink channel is reconstructed based on the channel parameters recovered according to the uplink channel. By means of the high angular resolution of the co-prime array, the problem that a recovered uplink channel cannot be directly used for pre-coding of a downlink channel is solved.