Overlayed Cell Access Using SSB Equivalent Indications

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Solution Overview

Problem

Existing wireless communication systems face limitations in multiple-TRP cell deployments due to restricted SSB indexing, increased deployment complexity, and reduced PRACH capacity, as well as the need for complex scheduler coordination in multiple-TRP cells.

Innovation Solution

Implementing a method where a first TRP transmits both a first SSB corresponding to a first cell and a second SSB corresponding to a second cell, allowing UEs to connect to a multiple-TRP cell through an SSB equivalent indication, which can be conveyed in an MSG4 message or RRC configuration, thereby enabling seamless handovers and optimizing resource usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a single TRP serves a single cell with unique SSB indexing, then cell identification and access are straightforward, but PRACH capacity is reduced and deployment complexity increases in multiple-TRP scenarios

Engineering Contradiction:
Improvecell access simplicityVSAvoiddeployment complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The first TRP is configured to transmit both the first SSB corresponding to the first cell and the second SSB corresponding to the second cell, making the TRP multi-functional in serving multiple cells. This universal approach allows a single TRP to handle multiple cell identities without requiring additional TRPs or complex coordination mechanisms.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the functionality of multiple SSB transmissions from a single TRP into one unified transmission point. Instead of having separate TRPs for each cell, the first TRP merges the transmission of multiple SSBs, thereby reducing overall network complexity while maintaining the ability to serve multiple cells independently.

Inventive Principle:
Principle #5Merging (Combining)

2Area of stationary object

If multiple TRPs are deployed to serve overlayed cells, then coverage and capacity are improved, but SSB indexing becomes restricted and PRACH resources are insufficient

Engineering Contradiction:
Improvecoverage areaVSAvoidPRACH resources
Core Design Contradiction:
Area of stationary objectVSQuantity of substance

Solution Approach 1:

The patent introduces a new dimension in cell identification by using SSB equivalent indication that maps to a different cell than the one actually accessed. Instead of relying solely on traditional cell-specific SSB indexing, the system uses an indirect mapping approach where the SSB equivalent field in MSG4 or RRC configuration provides an alternative cell identity, effectively adding a new layer to the resource allocation structure.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The SSB equivalent indication acts as an intermediary mechanism between the random access procedure and the actual cell connection. Rather than directly binding PRACH resources to specific cells, the patent introduces this intermediate mapping layer that allows flexible resource allocation and cell association without requiring dedicated PRACH resources for each cell.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If SSB equivalent indication is used to enable UE connection to overlayed cells, then handover robustness and resource utilization improve, but the complexity of the access procedure increases

Engineering Contradiction:
Improvehandover robustnessVSAvoidaccess procedure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The network pre-configures the SSB equivalent indication mapping before the random access procedure begins. The relationship between accessed cells and equivalent indicated cells is established in advance through network configuration, so that during the actual access procedure, the UE and network can efficiently resolve cell associations without complex real-time calculations or negotiations.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4169298B1Overlayed cell access handling
Publication Date: 2025.09.17 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP4169298B1 patent drawingFigure 1
  • EP4169298B1 patent drawingFigure 2
  • EP4169298B1 patent drawingFigure 3~4

AI summary

A method of establishing a connection between a wireless device and a wireless communication network includes receiving, at a first transmission/reception point, TRP, a random access request from the wireless device on a random access channel of a first cell associated with the first TRP, and transmitting, by the first TRP, a synchronization signal block, SSB, equivalent indication to the wireless device, wherein the SSB equivalent indication corresponds to a second cell.