Primary Cell Change in Carrier Aggregation

Solution Overview

Problem

The existing carrier aggregation procedures in 3GPP LTE networks face significant interruptions and irrecoverable failures when the primary cell link is interrupted, as they require a handover procedure that involves synchronization and protocol re-establishment, leading to loss of buffered packets and communication disruptions.

Innovation Solution

A method for changing the primary cell during carrier aggregation operations by transmitting a primary cell change message from the base station to the mobile station, allowing seamless transition to a new primary cell without interrupting uplink control information transfer, using a Radio Resource Control message and random access channel transmission, which reduces communication disruptions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If handover procedure is used to change primary cell, then primary cell can be changed to maintain communication quality, but significant communication interruptions and packet loss occur

Engineering Contradiction:

Improvecommunication link qualityVSAvoidcommunication interruption duration

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The target cell is pre-configured with all necessary parameters including cell identity, frequency information, and synchronization details before the actual switch occurs. The base station prepares the target cell configuration in advance and transmits it to the mobile station, enabling the mobile station to switch to the target cell without waiting for on-demand configuration or experiencing prolonged setup time.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces a dedicated primary cell change message as an intermediary mechanism that coordinates the switch between source and target cells. This message acts as a mediator carrying pre-configured target cell parameters, allowing the mobile station to perform the handover based on prepared information rather than reacting to real-time conditions, thus reducing interruption time.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If handover procedure is used to change primary cell, then primary cell can be changed, but protocol re-establishment is required causing packet loss

Engineering Contradiction:

Improvecommunication link qualityVSAvoidbuffered packet loss

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The target cell is pre-configured with all necessary parameters including cell identity, frequency information, and synchronization details before the actual switch occurs. The base station prepares the target cell configuration in advance and transmits it to the mobile station, enabling the mobile station to switch to the target cell without waiting for on-demand configuration or experiencing prolonged setup time.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces a dedicated primary cell change message as an intermediary mechanism that coordinates the switch between source and target cells. This message acts as a mediator carrying pre-configured target cell parameters, allowing the mobile station to perform the handover based on prepared information rather than reacting to real-time conditions, thus reducing interruption time.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Stability of the object's composition

If random access channel transmission is used for primary cell change, then synchronization can be achieved, but communication disruptions occur

Engineering Contradiction:

ImprovesynchronizationVSAvoidcommunication disruption duration

Core Design Contradiction:

Stability of the object's compositionVSLoss of time

Solution Approach 1:

The target cell is pre-configured with all necessary parameters including cell identity, frequency information, and synchronization details before the actual switch occurs. The base station prepares the target cell configuration in advance and transmits it to the mobile station, enabling the mobile station to switch to the target cell without waiting for on-demand configuration or experiencing prolonged setup time.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9883424B2Method and apparatus for change of primary cell during carrier aggregation

Publication Date: 2018.01.30 GOOGLE TECHNOLOGY HOLDINGS LLC

AI summary

Methods for performing change of primary cell during carrier aggregation operation are described. A mobile station (MS) receives a message to change a primary cell and to perform a random access communication with a new primary cell. Upon receiving a random access response message from the new primary cell, the MS starts transmitting a control channel to the new primary cell. In one embodiment, the MS releases the configuration of an uplink control channel and transmits uplink control information through an uplink shared channel. Upon completion of the primary cell change procedure, the MS starts transmission of an uplink control channel to the new primary cell.