Radio Terminal Feedback Interval Optimization for Coordinated MIMO

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Solution Overview

Problem

In coordinated base station MIMO communications, the overhead associated with feedback increases due to the need for multiple radio base stations to receive channel information from a radio terminal, leading to potential delays and disruption of communication.

Innovation Solution

A radio communication system where the radio terminal provides feedback to one radio base station with a longer interval than to another, allowing the first base station to update its transmission antenna weights based on this feedback, and during omitted feedback periods, the terminal provides channel information to the second base station, which normalizes and uses it to transmit signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If feedback control channels are established between the radio terminal and all multiple radio base stations, then coordinated base station MIMO communications can function normally, but the overhead associated with feedback increases and radio resource consumption increases in the uplink

Engineering Contradiction:

Improvecoordinated base station MIMO communications functionVSAvoidfeedback overhead

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the feedback mechanism into two segments: one feedback control channel established with a first radio base station for normal coordinated MIMO operation, and a separate mechanism where channel information is normalized and fed back only to the second radio base station during feedback omission periods. This segmentation reduces feedback overhead while maintaining communication reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements periodic feedback omission periods where the radio terminal omits feedback to the first radio base station during specific time intervals. During these periods, channel information is normalized and fed back to the second radio base station instead. This periodic action reduces average feedback overhead while maintaining system functionality.

Inventive Principle:

Principle #19Periodic action

2Productivity

If feedback is provided to all multiple radio base stations, then each base station can update transmission antenna weights in real-time, but the time interval for feedback updates must be reduced increasing resource consumption

Engineering Contradiction:

Improvetransmission antenna weight update speedVSAvoidradio resource consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent applies partial action by having the radio terminal provide feedback only to the first radio base station during normal periods, and only to the second radio base station during feedback omission periods. This partial feedback approach reduces the total amount of feedback transmission while still enabling both base stations to obtain necessary channel information for weight updates.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The second radio base station acts as an intermediary during feedback omission periods. The radio terminal provides normalized channel information to the second base station, which then uses this information to transmit signals to the first base station. This intermediary mechanism enables indirect information transfer, reducing direct feedback overhead while maintaining system coordination.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If the radio terminal provides feedback to one radio base station with a longer interval, then feedback overhead is reduced, but the other radio base station may not receive timely feedback for normal operation

Engineering Contradiction:

Improvefeedback overheadVSAvoidfeedback timeliness

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent implements dynamic feedback mechanisms where the feedback target base station changes based on operational requirements. During normal operation, feedback goes to the first base station with longer intervals. During feedback omission periods, the system dynamically switches to providing normalized channel information to the second base station. This dynamic adaptation maintains reliability while reducing overall overhead.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the feedback parameter by normalizing channel information before feedback during omission periods. This parameter change allows the second radio base station to process and utilize the feedback information effectively, ensuring timely and accurate signal transmission even when feedback intervals are extended for the first base station.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9191085B2Radio communication system, radio terminal, and radio communication method

Publication Date: 2015.11.17 KYOCERA CORP

AI summary

A radio communication system (1) has: a radio terminal (UE); a radio base station (BS1) which transmits radio signals (RS1) to the radio terminal (UE) corresponding to the feedback from the radio terminal (UE); and a radio base station (BS2) which transmits, corresponding to the feedback from the radio terminal (UE), radio signals (RS2) to the radio terminal (UE) at the frequency and time identical to the frequency and time at which the radio signals (RS1) are transmitted. The time interval at which the radio terminal (UE) performs the feedback to the radio base station (BS1) is longer than the time interval at which the radio terminal (UE) performs the feedback to the radio base station (BS2).