PBCH-Assisted Synchronization for DRX Power Reduction

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Solution Overview

Problem

During Discontinuous Reception (DRX) operation in mobile communication devices, synchronization with the service network is inefficient, leading to increased power consumption and timing drift due to the low time domain density of pilot/reference signals, and existing solutions either consume more power or are costly.

Innovation Solution

The use of a Physical Broadcast Channel (PBCH) for synchronization during DRX operation, allowing the mobile device to wake up and synchronize more quickly and efficiently, reducing power consumption and hardware costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the mobile device uses pilot/reference signals to re-synchronize with the service network during DRX operation, then the device can recover synchronization, but the additional wake-up time increases power consumption

Engineering Contradiction:

Improvesynchronization recoveryVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies preliminary action by having the mobile device perform synchronization operations before entering sleep mode. The device acquires timing and frequency information from PBCH signals during the ON duration, prepares synchronization parameters, and stores them for use during the OFF duration. This allows the device to quickly re-synchronize during brief wake-up periods without requiring extended pilot signal reception, thereby reducing power consumption while maintaining reliable synchronization recovery.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the mobile device performs a cell search to acquire timing and frequency information after detecting out-of-sync, then the device can re-synchronize, but the process takes a long time and consumes more power

Engineering Contradiction:

Improvesynchronization recoveryVSAvoidsynchronization time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by performing synchronization acquisition during the ON duration before entering sleep mode. The device extracts timing and frequency information from PBCH signals in advance, prepares synchronization parameters, and stores them for quick retrieval during the OFF duration. This eliminates the need for time-consuming cell search procedures during wake-up periods, significantly reducing synchronization time while maintaining reliable re-synchronization capability.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the mobile device uses a better crystal to maintain timing drift and frequency offset during sleep mode, then synchronization is maintained, but the hardware cost increases significantly

Engineering Contradiction:

Improvesynchronization maintenanceVSAvoidhardware cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by acquiring and storing synchronization parameters from PBCH signals before entering sleep mode. The device prepares timing and frequency compensation parameters in advance during the ON duration, so that during the OFF duration, it only needs to retrieve and apply these pre-computed parameters rather than maintaining precise timing through expensive crystal oscillators. This approach maintains synchronization reliability while avoiding the need for costly hardware improvements.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies copying by creating a digital copy of synchronization parameters (timing and frequency information) from the PBCH signals during the ON duration. Instead of relying on expensive physical crystal oscillators to maintain timing, the device copies the essential synchronization data into memory and uses this digital replica during sleep mode. This virtual copy replaces the need for expensive hardware components while maintaining synchronization accuracy.

Inventive Principle:

Principle #26Copying

4Use of energy by moving object

If the mobile device enters sleep mode during OFF duration of DRX operation, then power is conserved, but the device becomes unsynchronized with the service network

Engineering Contradiction:

Improvepower consumptionVSAvoidsynchronization

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies preliminary action by having the mobile device acquire and store synchronization parameters from PBCH signals during the ON duration before entering sleep mode. The device prepares timing and frequency compensation parameters in advance, so that during the OFF duration, it can remain in low-power sleep mode while maintaining the ability to quickly re-synchronize using the pre-acquired parameters. This resolves the contradiction by enabling both power conservation during sleep and synchronization maintenance through advance preparation.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10004053B2Apparatuses and methods for physical broadcast channel (PBCH) assisted synchronization during a discontinuous reception (DRX) operation

Publication Date: 2018.06.19 MEDIATEK INC

AI summary

A mobile communication device with a Radio Frequency (RF) unit and a processing unit is provided. The RF unit transmits and receives wireless signals to and from a service network. The processing unit configures the RF unit to communicate with the service network in a DRX operation, and uses a Physical Broadcast Channel (PBCH) for synchronizing with the service network during the DRX operation.