Satellite Massive MIMO Precoding for Beam Squint Mitigation
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Solution Overview
Problem
Satellite massive MIMO integrated sensing and communication systems face challenges in accurately estimating instantaneous electromagnetic wave propagation status due to high propagation delay, Doppler shift, and rapidly changing channel dimensions.
Innovation Solution
A method that estimates statistical status information of electromagnetic wave propagation using uplink and downlink pilot signals, allowing for the transmission of directional beams and downlink signals through integrated sensing and communication precoding, which is updated dynamically to account for changes in propagation conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If instantaneous status information estimation is used in satellite massive MIMO integrated sensing and communication, then communication and sensing functions can be implemented, but accurate estimation becomes difficult due to high propagation delay, large Doppler shift, and rapidly changing channel dimensions
Solution Approach 1:
The patent uses uplink pilot signals as a copy or reference to infer downlink channel characteristics. By transmitting uplink pilot signals and receiving them at the satellite, the system creates a reference copy of the propagation conditions that can be used to estimate downlink channel status without requiring direct downlink pilot transmission, thus reducing complexity while maintaining estimation accuracy.
Solution Approach 2:
The patent introduces statistical status information as an intermediary representation of the electromagnetic wave propagation channel. Instead of directly estimating complex instantaneous channel parameters, the system uses statistical characteristics (such as channel gain, channel direction vector, and angles of departure) as intermediate variables that capture essential propagation properties while simplifying the estimation process in high-Doppler satellite environments.
2Productivity
If beam squint is considered in wideband satellite massive MIMO, then frequency reuse between communication and sensing is improved, but system performance is affected by beam squint effects
Solution Approach 1:
The patent applies different precoding strategies to different frequency subcarriers to account for beam squint effects. By adjusting the precoding weights locally for each frequency component based on the beam squint characteristics, the system maintains focused beams across the wideband spectrum while enabling frequency reuse between communication and sensing functions.
Solution Approach 2:
The patent implements dynamic precoding adjustment that adapts to frequency-dependent beam squint effects. The integrated sensing and communication precoding is updated based on statistical status information that captures the dynamic propagation conditions, allowing the system to maintain optimal performance across different frequency bands despite beam squint.
3Adaptability or versatility
If integrated sensing and communication precoding is updated dynamically, then adaptation to changing propagation conditions is improved, but computational complexity increases
Solution Approach 1:
The patent updates precoding parameters selectively rather than completely recomputing all precoding matrices. By updating only the essential parameters (such as channel direction vectors and statistical status information) that change with propagation conditions, the system achieves adaptability while reducing computational complexity compared to full precoding recomputation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively mitigates the effects of beam squint, enhances energy efficiency and communication performance, and improves radar resolution by efficiently utilizing spectrum resources and enabling flexible switching between communication and sensing functions.
Implementation Method 1
the satellite end estimates statistical status information of electromagnetic wave propagation according to received uplink and downlink pilot signals
Implementation Method 2
the satellite end transmits a directional beam to a detection target and a downlink signal to each user terminal by means of integrated sensing and communication precoding
Implementation Method 3
the mobility of the user terminal and the detection target may lead to a large Doppler shift
Data Source
AI summary
Disclosed is a transmit method based on satellite massive Multiple-Input Multiple-Output (MIMO) integrated sensing and communication, where a satellite end is equipped with a massive MIMO array to implement an integrated sensing and communication system. The satellite end sends a communication signal to multiple user terminals based on statistical properties of electromagnetic wave propagation, and detects multiple targets simultaneously, thus realizing simultaneous communication of the satellite end with the user terminals and sensing for the targets. The present disclosure fully utilizes the spectrum resources, implements a flexible switch between wireless communication and target sensing functions based on a satellite, and mitigates the effects of the beam squint on system performance, thus greatly improving communication performance and radar resolution and being applicable for construction of an integrated network of space, air, ground and sea to achieve global coverage.