PUCCH Carrier Switching for Latency Reduction in URLLC

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Solution Overview

Problem

Existing telecommunications systems in cellular communications networks face challenges in efficiently transmitting control information, particularly in scenarios requiring low latency and high reliability, such as URLLC services. The current system is restrictive, allowing PUCCH transmission only on the primary cell or PUCCH-SCell, which can lead to higher latency due to limited uplink opportunities in TDD patterns.

Innovation Solution

The proposed solution involves semi-static configuration for PUCCH carrier switching, allowing periodic PUCCH transmissions to switch between available cells based on configured periodic occasions and available resources. This flexibility is achieved through the use of a sequence of PUCCH carrier indices and resource IDs, enabling dynamic allocation of resources for PUCCH transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If PUCCH transmission is restricted to only primary cell or PUCCH-SCell, then system complexity is reduced, but transmission latency increases due to limited uplink opportunities in TDD patterns

Engineering Contradiction:

Improvesystem complexityVSAvoidtransmission latency

Core Design Contradiction:

Device complexityVSLoss of time

Solution Approach 1:

The patent implements dynamic PUCCH carrier switching where the UE can switch between primary cell, PUCCH-SCell, and other SCells based on real-time availability of uplink opportunities in TDD patterns. This dynamic adaptation allows the system to exploit available uplink resources across multiple cells, reducing transmission latency while maintaining manageable complexity through standardized switching mechanisms.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent enables multiple cells to serve the dual function of data transmission and PUCCH transmission. By configuring multiple SCells that can alternatively carry PUCCH transmissions, the system creates a universal resource pool where any cell can potentially handle control information, thereby increasing uplink opportunities and reducing latency without proportionally increasing system complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Loss of time

If PUCCH transmission is allowed on multiple cells, then transmission latency is reduced through increased uplink opportunities, but device complexity increases due to carrier switching mechanisms

Engineering Contradiction:

Improvetransmission latencyVSAvoiddevice complexity

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of PUCCH transmission by allowing flexible configuration of multiple SCells that can alternatively carry PUCCH transmissions. This parameter change enables the system to adapt to varying network conditions and TDD patterns, reducing latency through increased transmission opportunities while managing device complexity through standardized configuration procedures.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If semi-static configuration is used for PUCCH carrier switching, then adaptability to network conditions is improved, but control signaling overhead increases

Engineering Contradiction:

Improveadaptability to network conditionsVSAvoidcontrol signaling overhead

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent employs semi-static configuration where the network pre-configures multiple SCells that can alternatively carry PUCCH transmissions. This preliminary action prepares the system in advance for varying network conditions and TDD patterns, enabling rapid adaptation without requiring extensive real-time control signaling. The UE can then switch carriers based on pre-established configurations, reducing signaling overhead while maintaining high adaptability.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20250141638A1Pucch carrier-switching for semi-statically configured periodic pucch

Publication Date: 2025.05.01 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

User equipments, network nodes, and systems are described to transmitting and receiving a physical uplink control channel, PUCCH. For example, a user equipment may receive configuration information from a network node. The configuration information may indicate a plurality of cells available for transmitting or for receiving the PUCCH, the plurality of cells including a reference cell and a designated cell and may indicate a periodicity indicating a period for transmitting the PUCCH, the period being associated with the reference cell. The user equipment may transmit the PUCCH via the designated cell in accordance with the period associated with the reference cell.