RIS Reflection Pattern Timing Offset for Beam Synchronization
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Solution Overview
Problem
In wireless communication systems, there is a need for synchronizing the timing of RIS reflection patterns with data signals to ensure optimal beamforming, as transmission paths of control and data signals may differ, leading to delays and inappropriate beam pattern switching.
Innovation Solution
A method and apparatus that identify the delay time caused by the radio unit buffer and determine an RIS offset value for synchronization, transmitting a first signal to a terminal through the RIS reflection plane at a first time point and a second signal for controlling the reflection pattern at a second time point with the applied offset value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If control signal and data signal are transmitted simultaneously through different paths to RIS, then transmission efficiency is improved, but timing synchronization deteriorates due to different path delays
Solution Approach 1:
The base station performs preliminary calculation of path delays between transmission and reflection points for both control and data signals. Based on these pre-calculated delay values, the base station determines appropriate timing offsets and applies them when transmitting signals, ensuring that the control signal arrives at the RIS at the correct time relative to the data signal, thus maintaining synchronization while allowing simultaneous transmission paths
Solution Approach 2:
The invention changes the timing parameter of the control signal transmission by applying a calculated offset. The base station adjusts the transmission time of the control signal based on the difference in path delays between control and data signals, thereby compensating for the timing mismatch caused by different transmission paths and ensuring synchronized arrival at the RIS
2Device complexity
If RIS reflection pattern switching is performed without delay compensation, then device complexity is reduced, but beamforming accuracy deteriorates due to timing misalignment
Solution Approach 1:
The base station autonomously calculates the path delays and determines the required timing offset without requiring complex external synchronization mechanisms or feedback from the RIS. The RIS simply applies the reflection pattern when the control signal arrives, and the base station's self-calculated timing compensation ensures beamforming accuracy is maintained while keeping the RIS device complexity low
Data Source
AI summary
The present disclosure relates to a fifth generation (5G) communication system or a sixth generation (6G) communication system for supporting higher data rates beyond a 4G communication system such as long term evolution (LTE). In a wireless communication system, a method performed by a base station includes identifying a delay time caused by a radio unit (RU) buffer, determining an RIS offset value for synchronization of signals transmitted to a reconfigurable intelligent surface (RIS), based on the delay time caused by the RU buffer, transmitting, to the RIS, a first signal to be transmitted to a terminal through a reflection plane of the RIS at a first time point, and transmitting, to the RIS, a second signal for controlling a reflection pattern of the RIS at a second time point to which the RIS offset value is applied.