Relay Node Scheduling for LTE-Advanced Interference Reduction

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Solution Overview

Problem

In LTE-Advanced mobile communication systems, interference occurs in relay nodes when simultaneous transmission-and-reception processes in Un and Uu radio bearers overlap, causing signal looping and interference in the reception circuit.

Innovation Solution

The method involves scheduling downlink signals by the radio base station and relay node to ensure non-overlapping transmission timings based on operating frequencies, with the relay node determining necessary scheduling adjustments and notifying the base station, and utilizing time division multiplexing to manage resource switching between the Un and Uu bearers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If simultaneous transmission-and-reception processes in Un and Uu radio bearers are performed, then communication efficiency is improved, but interference occurs in the relay node's reception circuit due to signal looping

Engineering Contradiction:
Improvecommunication efficiencyVSAvoidinterference in reception circuit
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent segments the transmission and reception processes into separate time slots. The relay node divides its operation into distinct periods where it either transmits to the mobile station or receives from the base station, but not both simultaneously. This temporal segmentation eliminates signal looping interference while maintaining communication efficiency through proper resource allocation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements periodic action by establishing regular time-division multiplexing cycles between transmission and reception operations. The relay node alternates between transmitting downlink signals to mobile stations and receiving uplink signals from the base station in a periodic manner, ensuring that interference-free operation is maintained while achieving efficient resource utilization.

Inventive Principle:
Principle #19Periodic action

2Object-affected harmful factors

If time division multiplexing is used to separate transmission and reception timing, then interference is reduced, but resource allocation complexity increases

Engineering Contradiction:
ImproveinterferenceVSAvoidresource allocation complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by having the relay node determine and report its transmission timing requirements to the base station in advance. The base station then pre-configures the time-division multiplexing schedule based on this information, eliminating the need for complex real-time coordination and reducing resource allocation complexity while effectively preventing interference.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback mechanisms where the relay node reports its determination results regarding transmission timing to the base station. This feedback enables the base station to adjust and optimize the time-division multiplexing configuration, simplifying resource allocation while ensuring interference-free operation through coordinated scheduling.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP2487979B1Mobile communication method and relay node
Publication Date: 2015.12.16 NTT DOCOMO INC
  • EP2487979B1 patent drawingFigure 1
  • EP2487979B1 patent drawingFigure 2
  • EP2487979B1 patent drawingFigure 3(a)~3(b)

AI summary

Interference to a reception circuit of a relay node itself is reduced, which occurs when transmission-and-reception process in a Un radio bearer and transmission-and-reception process in a Uu radio bearer are simultaneously performed. A mobile communication method according to the present invention includes a step of determining, by a relay node RN, whether it is necessary to perform the scheduling of a second timing such that the second timing does not overlap a first timing in a time direction, based on a first operating frequency f1 used in a radio zone between the relay node RN and a mobile station UE and a second operating frequency f2 used in a radio zone between a radio base station DeNB and the relay node RN, and a step of notifying, by the relay node RN, the radio base station DeNB of the determination result.