Relative Beam Feedback for MIMO Pre-coding Reliability
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Solution Overview
Problem
In MIMO radio communication systems, pre-coding beam selection reliability is compromised due to feedback signal determination errors, especially in asymmetric communication lines with insufficient upload path reliability, leading to decreased communication quality and throughput.
Innovation Solution
A radio communication system that includes a beam selector, a beam information generator, and a feedback information transmitter at the reception station, and a beam information acquirer, pre-coding processor, and control information generator at the transmission station, which use relative beam information to enhance the reliability of beam selection by pre-coding, even in asymmetric communication line conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pre-coding beam selection is performed using feedback signals in asymmetric communication lines, then communication capacity is improved, but feedback signal determination errors occur leading to decreased reliability
Solution Approach 1:
The patent implements a feedback mechanism where the reception station sends beam information to the transmission station, and the transmission station uses this feedback to perform pre-coding. The system continuously adjusts beam formation based on feedback signals, improving communication capacity while managing reliability through iterative optimization rather than single-shot selection.
Solution Approach 2:
The patent changes the parameter representation from absolute beam indices to relative beam information (differences between consecutive beam selections). This parameter transformation reduces the information transmission burden and enables more robust beam selection in asymmetric communication lines, thereby improving reliability without sacrificing communication capacity.
2Loss of information
If absolute beam information is transmitted in feedback signals, then complete beam selection information is provided, but communication quality decreases due to determination errors in asymmetric paths
Solution Approach 1:
The patent extracts only the essential information needed for beam selection by transmitting relative beam information (differences) rather than complete absolute beam indices. This extraction approach reduces the information load in feedback signals, minimizing determination errors in asymmetric communication paths while maintaining sufficient beam selection accuracy.
Solution Approach 2:
The patent transforms the feedback parameter from absolute beam indices to relative differences between consecutive beam selections. This parameter change reduces the bit requirement and information complexity, thereby improving feedback signal reliability in asymmetric communication lines while still providing complete beam selection capability through differential encoding.
3Reliability
If error correction codes are added to feedback paths, then reliability is improved, but communication efficiency decreases due to increased overhead
Solution Approach 1:
The patent changes the feedback parameter representation to relative beam information, which requires fewer bits to transmit than absolute beam indices. This parameter transformation inherently reduces the information burden, providing a form of compression that improves efficiency without requiring additional error correction overhead, thus avoiding the reliability-efficiency trade-off.
Solution Approach 2:
The patent applies partial error protection by using differential encoding that naturally reduces information content, rather than applying full error correction codes. This partial approach (using relative information) provides sufficient reliability for beam selection while maintaining high communication efficiency by avoiding the overhead of comprehensive error correction mechanisms.
Data Source
AI summary
Reliability of beam selection by pre-coding is improved. A user terminal 52 selects an optimum beam (beam number ‘b’) in the next frame (t+1) based on the channel estimation value of a received pilot signal and transmits a difference value D (=b−a) between a beam number ‘a’ at the current transmission notified by a radio base station 51 and the selected beam number ‘b’ selected to be transmitted at the next transmission to the radio base station 51 as a feedback signal. The radio base station 51 previously stores the beam number ‘a’ notified at the previous transmission and combines the beam number based on the difference value D received as the received feedback signal and the previously notified beam number ‘a’ to restore the beam number ‘b’ desired by the user terminal 52. Pre-coding processing adapted to the beam number ‘b’ is performed and transmission to the user terminal 52 is executed in a state in which a beam of the appropriate beam number ‘b’ is formed.