LTE-M Subcarrier Puncturing for NR PRB Misalignment

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Solution Overview

Problem

The challenge of achieving efficient coexistence between LTE-M and NR networks is exacerbated by downlink PRB grid misalignment, leading to inefficient NR resource utilization and potential performance loss for LTE-M devices due to punctured subcarriers.

Innovation Solution

Implementing LTE-M subcarrier puncturing to minimize the number of outlying subcarriers that exceed NR PRB boundaries, ensuring efficient coexistence by selectively applying puncturing to different physical channels and resource allocations, and signaling this puncturing effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If LTE-M is deployed within NR carrier bandwidth, then LTE-M coexistence with NR is enabled, but PRB grid misalignment causes inefficient NR resource utilization

Engineering Contradiction:

ImproveLTE-M coexistence with NRVSAvoidNR resource utilization efficiency

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent segments the LTE-M carrier bandwidth into multiple narrowbands, where each narrowband is further divided into resource blocks. This segmentation allows selective mapping of LTE-M resource blocks to NR physical resource blocks, enabling efficient resource utilization by only allocating NR resources where LTE-M actually needs them, thus resolving the PRB grid misalignment issue while maintaining coexistence.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by allowing different mapping configurations for different narrowbands within the LTE-M carrier. Each narrowband can be independently mapped to NR resource blocks based on local conditions, enabling optimized resource allocation in each segment rather than a uniform approach, thereby improving overall NR resource utilization efficiency.

Inventive Principle:

Principle #3Local quality

2Reliability

If LTE-M subcarriers exceed NR PRB boundaries, then complete LTE-M resource allocation is maintained, but outlying subcarriers cause performance loss and resource waste

Engineering Contradiction:

ImproveLTE-M service continuityVSAvoidNR resource waste

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies partial action by transmitting only the necessary portion of LTE-M subcarriers that fall within NR PRB boundaries. Outlying subcarriers that would exceed boundaries are excluded from transmission. This partial transmission approach maintains reliable service for in-boundary subcarriers while avoiding the energy waste and performance loss associated with transmitting outlying subcarriers that cannot be properly received.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS12568481B2Applicability of LTE-M subcarrier puncturing in coexistence with NR

Publication Date: 2026.03.03 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

In one aspect, a network device transmits using a first carrier having a predetermined number of subcarriers within the bandwidth of a second carrier, such that data for one or more of the predetermined number of subcarriers corresponding to a partial overlap by the first carrier of a resource block of the second carrier is not transmitted. In another aspect, the wireless device receives using a first carrier having a predetermined number of subcarriers within the bandwidth of a second carrier, such that one or more of the predetermined number of subcarriers corresponding to a partial overlap by the first carrier of a resource block of the second carrier are discarded when decoding the received signal.