IRS Channel Estimation Using Angle-of-Arrival Path Separation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing communication systems using intelligent reflecting surfaces (IRS) face challenges in accurately estimating channel state information due to the non-linear relationship between millimeter wave channel parameters, which affects the performance of direct and indirect channel estimation.
Innovation Solution
A method is proposed that involves receiving signals through both direct and indirect paths, estimating angles of arrival using algorithms like root-MUSIC and maximum likelihood estimation, and calculating path gains based on these estimates, thereby reducing computational complexity and improving estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a base station completely turns elements of an intelligent reflecting surface off to estimate a direct channel first, then turns the intelligent reflecting surface on to estimate an indirect channel, then the direct channel can be estimated without interference, but the error of the first estimated direct channel information affects the performance of subsequent indirect channel estimation
Solution Approach 1:
The patent segments the channel estimation process into two distinct phases: first estimating the direct channel by turning off IRS elements, then estimating the indirect channel by turning on the IRS. This segmentation allows separate optimization of each estimation phase while managing the error propagation issue through sequential processing.
Solution Approach 2:
The patent performs preliminary action by first estimating the direct channel information before using it to estimate the indirect channel. This preliminary estimation is necessary to separate the direct and indirect path contributions, though it introduces error propagation that the system must manage through the sequential estimation approach.
2Reliability
If a base station estimates a direct path channel and an indirect path channel together, then mutual estimation performance problems are solved, but channel state information between the base station and an intelligent reflecting surface should be known in advance
Solution Approach 1:
The patent uses the intelligent reflecting surface as an intermediary to enable simultaneous estimation of direct and indirect channels. By controlling the IRS reflection patterns, the system can separate the channel contributions without requiring prior knowledge of the base station-IRS channel, effectively using the IRS itself as the mediator for estimation.
Solution Approach 2:
The patent employs periodic action by having the intelligent reflecting surface cyclically change its reflection patterns between different states (e.g., reflective and non-reflective). This periodic switching enables the base station to distinguish between direct and indirect path signals through the time-varying nature of the reflected components, facilitating simultaneous estimation without prior channel knowledge.
3Measurement precision
If traditional channel estimation methods are used in millimeter wave band communication, then direct path and indirect path channels can be estimated, but the non-linear relationship between channel parameters makes accurate estimation difficult and increases computational complexity
Solution Approach 1:
The patent changes the approach from directly estimating complex non-linear channel parameters to estimating angles of arrival and path gains through geometric relationships. By transforming the estimation problem into angular domain measurements and using the relationship between direct and indirect path angles, the system reduces computational complexity while maintaining accuracy in millimeter wave band communication.
Data Source
AI summary
A method of estimating a channel of a base station in a communication system using an IRS may comprise: receiving a first signal through a direct path between a terminal and the base station from the terminal and a second signal through an indirect path through the IRS from the terminal; estimating a first angle of arrival of the second signal received from the IRS; estimating a second angle of arrival of a signal transmitted to the IRS by the terminal based on the estimated first angle of arrival; estimating a third angle of arrival of the first signal received from the terminal based on the estimated first angle of arrival; and estimating path gains on the direct path and the indirect path based on the estimated first angle of arrival to the estimated third angle of arrival.