Persistent Scheduling Base Station Retransmission Control

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Solution Overview

Problem

In LTE communications systems, mobile stations face inefficiencies and increased power consumption due to the inability to distinguish between base stations not transmitting data and those transmitting data that is not being received correctly, leading to unnecessary retransmissions when persistent scheduling is applied in downlink.

Innovation Solution

Implementing a base station and mobile station apparatus with predetermined retransmit timings for user data, where the base station conducts first transmissions based on persistent scheduling and subsequent transmissions at specific timings when errors occur, allowing the mobile station to receive data only at predetermined times, thereby reducing unnecessary receptions and conserving battery power.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If persistent scheduling is applied in downlink, then transmission efficiency is improved, but mobile station power consumption increases due to inability to distinguish between no transmission and transmission errors

Engineering Contradiction:
Improvetransmission efficiencyVSAvoidmobile station power consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The base station performs preliminary action by transmitting a specific signal in advance to indicate that no user data is being transmitted. This allows the mobile station to know beforehand that it does not need to monitor for retransmissions, thereby reducing power consumption while maintaining the benefits of persistent scheduling for actual data transmissions.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

A specific indicator signal is introduced as an intermediary between the base station's transmission state and the mobile station's reception behavior. This signal acts as a mediator that conveys information about the transmission state without requiring the mobile station to continuously monitor and decode potential data transmissions, thus reducing power consumption.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the mobile station attempts to receive data at every scheduled time, then data reception reliability is improved, but unnecessary receptions increase power consumption

Engineering Contradiction:
Improvedata reception reliabilityVSAvoidbattery power
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The base station transmits a preliminary indicator signal before the scheduled data transmission time to inform the mobile station whether data will be transmitted. This allows the mobile station to prepare appropriately - maintaining high reliability when data is sent while avoiding unnecessary power consumption when no data is transmitted.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The mobile station's reception behavior is made dynamic based on the received indicator signal. Instead of continuously attempting to receive data at every scheduled time, the mobile station adapts its reception activity according to the actual transmission state indicated by the base station, thereby optimizing the balance between reliability and power consumption.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP2187669B1Base station device, mobile station device, and communication control method
Publication Date: 2016.01.27 NTT DOCOMO INC
  • EP2187669B1 patent drawingFigure 1
  • EP2187669B1 patent drawingFigure 2
  • EP2187669B1 patent drawingFigure 3

AI summary

A base station apparatus in a radio communications system is disclosed. The radio communications system has a mobile station apparatus and the base station apparatus in communication with the mobile station apparatus to which is applied a scheduling scheme which allocates a radio resource for each of constant periods. The base station apparatus includes a first transmitting unit which conducts a first transmission of a first signal for each of the constant periods based on the scheduling scheme; and a second transmitting unit which conducts second and subsequent transmissions at predetermined timings when an error occurs in the first transmission.