Inter-Symbol Interference Cancellation in mmWave MIMO Systems
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Solution Overview
Problem
In mmWave communication systems, the propagation delay difference between multiple antenna signals leads to inter-symbol interference (ISI) due to the short cyclic prefix (CP) interval, which is insufficient to cover the delay spread, resulting in decreased transmission power and efficiency.
Innovation Solution
A method is proposed to measure and compensate for the propagation delay difference between signals transmitted through different antennas using cross-correlation and uplink feedback, adjusting the transmission timing to ensure that signals arrive simultaneously at the receiver, thereby preventing ISI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the CP interval is increased to solve inter-symbol interference, then ISI is reduced, but transmission power and transmission band efficiency decrease due to increased overhead
Solution Approach 1:
The system performs preliminary measurement of propagation delay differences between multiple antenna signals during a training phase, and uses this information to pre-compensate for ISI by adjusting transmission timing. This preliminary action eliminates the need to increase CP interval for ISI protection, as the timing adjustment is applied before data transmission begins.
Solution Approach 2:
The system changes the transmission timing parameter dynamically based on measured propagation delay differences. By adjusting the transmission time of signals from different antennas according to the measured delay characteristics, the system compensates for ISI without changing the CP interval, thus maintaining transmission efficiency while preventing interference.
2Productivity
If the OFDM symbol size is increased to reduce CP ratio, then transmission efficiency improves, but phase error estimation becomes difficult and time coherence cannot be guaranteed
Solution Approach 1:
The system performs preliminary measurement of propagation delay differences using training signals before data transmission. This preliminary measurement enables the system to compensate for timing differences without requiring large OFDM symbol sizes, thus maintaining both efficiency and measurement precision.
Solution Approach 2:
The system introduces an intermediary timing adjustment mechanism that mediates between the transmission signals from different antennas. By using the measured propagation delay information as an intermediary parameter to adjust transmission timing, the system achieves precise phase error estimation and time coherence without increasing symbol size.
3Productivity
If Multiple-Input Multiple-Output transmission is implemented, then data transmission rate increases, but propagation delay difference causes inter-symbol interference between multiple antenna signals
Solution Approach 1:
The system performs preliminary measurement of propagation delay differences between all antenna pairs during a training phase, and uses this information to pre-compensate for ISI. This preliminary action enables MIMO transmission to proceed at high rates without interference, as the timing compensation is established before data transmission begins.
Solution Approach 2:
The system uses feedback from training signal measurements to adjust transmission timing. The measured propagation delay differences are fed back to the transmitter, which then uses this information to compensate for ISI by adjusting the transmission time of signals from different antennas, enabling high-rate MIMO transmission without interference.
Data Source
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AI summary
The present disclosure relates to a pre-5th-Generation (5G) or 5G communication system to be provided for supporting higher data rates Beyond 4th-Generation (4G) communication system such as Long Term Evolution (LTE). The present invention provides a method and a device for cancelling inter-symbol interference in a wireless communication system.The present invention provides a method and a device for cancelling inter-symbol interference in a wireless communication system. A method for a base station in a wireless communication system can comprises the steps of: transmitting multiple synchronous signals through multiple antennas to a terminal; receiving information on a propagation delay difference among the multiple synchronous signals from the terminal; and determining signal transmission timing for each of the multiple antennas on the basis of the information on the propagation delay difference.