NB-IoT M-PBCH Reception via Cell-Specific CRS Frequency Shift
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Solution Overview
Problem
Current wireless access systems face challenges in efficiently transmitting and receiving downlink/uplink physical channels, particularly in NB-IoT systems, where in-band operation and coexistence with legacy LTE systems pose issues such as resource element collisions and accurate channel transmission.
Innovation Solution
A method and apparatus for a user equipment (UE) to receive a physical downlink broadcast channel (M-PBCH) in an NB-IoT system by calculating a frequency shift value for cell-specific reference signals (CRS) or M-CRS, allowing for accurate estimation and reception of resource elements, even in environments where legacy CRS and M-CRS coexist, thereby preventing collisions and ensuring accurate channel transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If NB-IoT system operates in-band with legacy LTE system, then spectrum efficiency is improved, but resource element collisions occur between M-CRS and legacy CRS
Solution Approach 1:
The patent applies local quality by making the CRS configuration cell-specific and UE-specific. Different cells can use different v-shift values to relocate CRS resource elements locally, avoiding collisions in specific areas while maintaining overall system operation. The frequency shift parameter v is adjusted per cell ID, creating localized resource allocation patterns that prevent collisions between co-channel cells.
Solution Approach 2:
The patent changes the frequency shift parameter v of the CRS resource elements based on cell ID. By dynamically adjusting this parameter, the system relocates CRS in frequency domain to avoid overlapping with legacy CRS. This parameter change enables flexible resource element allocation that adapts to different deployment scenarios and prevents resource conflicts.
2Measurement precision
If M-CRS is introduced for NB-IoT, then channel estimation accuracy is improved, but complexity of coexistence with legacy CRS increases
Solution Approach 1:
The patent segments the resource elements in frequency domain by introducing a frequency shift for M-CRS relative to legacy CRS. This segmentation separates the two CRS types into distinct resource regions, allowing independent processing and estimation. The UE can separately estimate channels for M-CRS and legacy CRS without interference, reducing processing complexity while maintaining accuracy.
Solution Approach 2:
The frequency shift parameter v acts as an intermediary that mediates between M-CRS and legacy CRS resource allocation. By introducing this intermediate parameter, the system creates a clear distinction between the two CRS types, simplifying the coexistence mechanism. The UE uses this parameter to identify and process the appropriate CRS type, reducing the complexity of distinguishing and processing multiple CRS formats.
3Reliability
If frequency shift calculation is performed for each cell, then resource element collision prevention is improved, but computational overhead increases
Solution Approach 1:
The patent performs preliminary action by pre-calculating the frequency shift parameter v based on cell ID before actual resource allocation. This pre-computation allows the system to establish collision-free resource patterns in advance, avoiding the need for complex real-time calculations during operation. The UE can use this pre-determined parameter for efficient resource element identification and processing.
Data Source
AI summary
The present invention may provide a method and apparatuses for transmitting and receiving a downlink/uplink physical channel when an in-band operation is supported by a radio access system that supports a narrow band Internet of things (NB-IoT). As an embodiment of the present invention, a method for receiving a physical downlink broadcasting channel (M-PBCH) by a terminal in a radio access system that supports a narrow band Internet of things (NB-IoT) system may comprise the steps of: receiving a higher layer signal indicating an in-band deployment mode; receiving a narrow band primary synchronization signal (M-PSS) and a narrow band secondary synchronization signal (M-SSS), configured for the NB-IoT systems; obtaining a cell identifier (N-Cell ID) of the NB-IoT system from the M-SSS; and receiving an M-PBCH using the N-Cell ID in the in-band deployment mode. In this instance, the in-band deployment mode indicates that the NB-IoT system is configured in a band of a legacy LTE system.