Variable Bandwidth Reference Signal Transmission for Wireless Devices

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Solution Overview

Problem

Current wireless communication networks face challenges in reducing power consumption in wireless devices and radio network nodes, particularly due to the constant transmission of Cell Reference Signals (CRS) which causes interference and requires nodes to remain always-on, leading to inefficiencies in energy usage and performance degradation during low network load periods.

Innovation Solution

Implementing a mechanism where radio network nodes transmit reference signals over a variable bandwidth, alternating between a narrower and wider bandwidth based on signal strength or quality indications from wireless devices, allowing for reduced power consumption while ensuring adequate signal availability during radio link failure procedures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If reference signals are transmitted continuously over full bandwidth, then signal quality and coverage are maintained, but power consumption increases and interference rises

Engineering Contradiction:

Improvesignal qualityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements discontinuous transmission of reference signals by alternating between active subframes (with full bandwidth reference signals) and dormant subframes (without reference signals). This periodic action maintains signal quality during active periods while reducing overall power consumption and interference during dormant periods, directly resolving the contradiction between continuous transmission reliability and energy efficiency

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system dynamically adapts reference signal transmission by switching between full bandwidth and reduced bandwidth modes based on network conditions and device requirements. This dynamic adjustment allows the system to maintain signal quality when needed while reducing power consumption and interference during low-activity periods, resolving the static contradiction through adaptive behavior

Inventive Principle:

Principle #15Dynamics

2Area of stationary object

If reference signals are transmitted over full bandwidth, then coverage area is maximized, but inter-cell interference increases

Engineering Contradiction:

Improvecoverage areaVSAvoidinter-cell interference

Core Design Contradiction:

Area of stationary objectVSObject-generated harmful factors

Solution Approach 1:

By implementing discontinuous reference signal transmission with alternating active and dormant subframes, the system reduces the time-averaged interference level while maintaining coverage area during active periods. This periodic transmission pattern allows coverage to be preserved when reference signals are transmitted while significantly reducing inter-cell interference overall

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent applies different transmission characteristics to different time resources (subframes), with full bandwidth reference signals transmitted only in active subframes and reduced or no transmission in dormant subframes. This local differentiation in transmission quality across time resources allows coverage maintenance where needed while reducing interference in other time periods

Inventive Principle:

Principle #3Local quality

3Reliability

If radio network nodes remain always-on for CRS transmission, then service availability is maintained, but energy efficiency decreases

Engineering Contradiction:

Improveservice availabilityVSAvoidenergy efficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The system enters dormant states during which reference signal transmission is reduced or suspended, allowing radio network nodes to save energy. Service availability is maintained during active periods when full transmission resumes, resolving the contradiction between continuous availability and energy efficiency through periodic on-off cycles

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent ensures that useful transmission actions (reference signals for coverage and synchronization) continue during active periods while being suspended during dormant periods. This continuity of useful action when needed, combined with strategic suspension during low-activity periods, maintains service reliability while improving energy efficiency

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentEP3673709B1Radio network node, wireless device and methods performed therein

Publication Date: 2024.10.02 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

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AI summary

Embodiments herein relate to a method performed by a radio network node (12,13) for handling communication of a wireless device (10) in a wireless communication network (1). The radio network node (12,13) is configured to provide a serving cell for the wireless device (10) on a lean carrier where reference signals are transmitted with a bandwidth that is variable between a first bandwidth and a second bandwidth, the second bandwidth being narrower than the first bandwidth, and wherein the wireless device (10) is configured with a discontinuous reception cycle. The radio network node transmits reference signals over a bandwidth that alternates between the first bandwidth and the second bandwidth in accordance with the discontinuous reception cycle configured for the wireless device (10). The radio network node further obtains an indication from the wireless device (10) or from a second radio network node (12,13), which indication indicates that a signal strength or quality of the serving cell for the wireless device (10) is below a threshold; and transmits, in response to the obtained indication, one or more reference signals over the first bandwidth.