Base Station Uplink Synchronization Control for Intermittent Reception

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Solution Overview

Problem

Uplink synchronization loss between a base station and a mobile station occurs during intermittent reception, leading to interference in previous and next sub-frames and inefficient use of battery and radio resources, especially when the DRX/DTX cycle is long, causing link adaptation issues and potential loss of reception responses.

Innovation Solution

The base station measures signal propagation delay by sending a synchronization request to the mobile station, which adjusts its uplink transmission timing using timing advance information, ensuring that uplink signals fall within a cyclic prefix and allowing for optimal link adaptation and reduced interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the mobile station performs intermittent reception with a long DRX/DTX cycle to save battery power, then energy consumption is reduced, but uplink synchronization is lost causing interference in previous and next sub-frames

Engineering Contradiction:

Improvebattery power consumptionVSAvoiduplink synchronization

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The base station performs preliminary action by measuring the uplink reception timing and generating timing advance information before the mobile station's next transmission. This allows the mobile station to pre-adjust its transmission timing to compensate for propagation delay changes that occur during intermittent reception, preventing synchronization loss and interference before they happen.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The base station implements a feedback mechanism by continuously measuring the uplink reception timing and sending timing advance information to the mobile station. This feedback loop allows the mobile station to adjust its transmission timing dynamically, maintaining uplink synchronization even during long DRX/DTX cycles when the mobile station is in standby state.

Inventive Principle:

Principle #23Feedback

2Reliability

If the mobile station continuously receives DL-SCCH to maintain synchronization, then uplink synchronization is maintained, but battery power is exhausted

Engineering Contradiction:

Improveuplink synchronizationVSAvoidbattery power consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

Instead of continuous reception, the system uses periodic action where the base station periodically measures uplink timing and sends timing advance information during the mobile station's active periods. The mobile station applies these timing adjustments during its intermittent reception cycles, achieving synchronization maintenance with reduced energy consumption compared to continuous reception.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The mobile station uses the timing advance information received from the base station to self-adjust its uplink transmission timing. This self-service mechanism allows the mobile station to maintain synchronization autonomously during intermittent reception without requiring continuous base station control signals, thereby reducing power consumption.

Inventive Principle:

Principle #25Self-service

3Reliability

If the mobile station adjusts transmission timing frequently to maintain synchronization, then uplink synchronization is maintained, but radio resources are wasted

Engineering Contradiction:

Improveuplink synchronizationVSAvoidradio resource consumption

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The base station applies partial action by measuring and updating timing advance information only when necessary, specifically when the mobile station is in active state and can receive control information. This avoids excessive timing adjustment signaling during long DRX/DTX cycles, reducing radio resource consumption while maintaining adequate synchronization.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The system changes the timing advance parameter dynamically based on the mobile station's reception state. During active periods, timing advance is updated and applied; during standby periods, the mobile station uses the previously adjusted timing. This parameter change strategy maintains synchronization while minimizing the frequency of timing adjustment transmissions, thereby conserving radio resources.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP2787781B1Base station, mobile station, synchronization control method, and IC chip

Publication Date: 2017.04.26 NTT DOCOMO INC

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AI summary

A synchronization control method in a communication system including a mobile station performing an intermittent reception and a base station, including: generating, at the base station, a synchronization request (S103), when data addressed to the mobile station arrives (S101); receiving, at the mobile station, the synchronization request from the base station (S103); transmitting, at the mobile station, feedback information, as a response to the synchronization request (S105); receiving, at the base station, the feedback information (S105); and measuring, at the base station, a signal propagation delay time by using a reception timing of the feedback information (S107).