Cooperative Donor Cell Selection in LTE-Advanced Relay Networks

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Solution Overview

Problem

In LTE-Advanced mobile communication systems, the existing donor cell selection method solely based on relay station information can lead to suboptimal choices, causing prolonged connection establishment times and disruptions when switching donor cells, especially when considering the load and status of base station cells and other relay stations.

Innovation Solution

A method where both the relay station and base station determine the donor cell by sharing and utilizing first and second cell management information, incorporating load status, connection quality, and performance criteria to select the most suitable donor cell, ensuring alignment with both sides' requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If donor cell selection is based solely on relay station information, then the selection process is simple and fast, but the selection quality is suboptimal causing prolonged connection establishment times and disruptions

Engineering Contradiction:

Improvedonor cell selection qualityVSAvoidconnection establishment time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent merges the donor cell selection functions of both the relay station and base station into a cooperative decision-making process. The relay station evaluates candidate cells based on connection quality, while the base station evaluates based on load status, and both perspectives are combined to make the final selection, resolving the contradiction between simple/fast selection and high-quality selection.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The base station pre-calculates and stores cell management information including load status and suitability evaluation results for multiple candidate cells. This preliminary action allows the relay station to quickly select from pre-evaluated options without requiring complex real-time calculations, thus improving selection quality while maintaining fast connection establishment.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If donor cell selection considers only relay station perspective, then the selection process is straightforward, but it causes disruptions when switching donor cells due to ignoring base station load and status

Engineering Contradiction:

Improverelay station operation reliabilityVSAvoidcommunication disruptions

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The base station provides feedback information about its load status and cell suitability to the relay station. The relay station uses this feedback to adjust its donor cell selection, avoiding cells that would cause base station overload or instability. This feedback mechanism ensures that donor cell switching considers base station conditions, reducing communication disruptions while maintaining straightforward selection process.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent introduces cell management information as an intermediary that carries base station's load status and suitability evaluation between the base station and relay station. This intermediary enables the relay station to make informed decisions that consider base station conditions without requiring direct complex interaction, thus reducing disruptions while keeping the selection process straightforward.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If both relay station and base station participate in donor cell determination, then the selection quality improves, but the complexity of the selection process increases

Engineering Contradiction:

Improvedonor cell selection qualityVSAvoidselection process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the donor cell selection process into distinct evaluation responsibilities: the relay station evaluates connection quality metrics, while the base station evaluates load status and overall suitability. This segmentation allows each entity to focus on its strengths without handling the entire complex decision-making process, improving selection quality while managing complexity through division of labor.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each entity (relay station and base station) performs self-service evaluation of its own metrics and provides results to the other. The relay station independently evaluates connection quality, the base station independently evaluates load status, and both use the other's results to make the final selection. This self-service approach improves selection quality through mutual evaluation while avoiding the complexity of one entity managing the entire selection process.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS8923871B2Mobile communication system, relay station, base station, control method thereof, and computer readable medium

Publication Date: 2014.12.30 NEC CORP

AI summary

A mobile communication system includes a base station and a relay station. The relay station acquires a donor cell list indicating at least one candidate cell that can be used for a backhaul link. The relay station or the base station determine a donor cell used for the backhaul link from the donor cell list based on both first and second cell management information. The first cell management information relates to the at least one candidate cell and originates from the at least one base station. The second cell management information originates from the relay station.