NB-IoT TDD Frequency Offset Signaling via MIB-NB Raster
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Solution Overview
Problem
Existing methods for determining the Downlink to Uplink (DL-to-UL) frequency offset in NB-IoT TDD networks, especially when deployed inside LTE or NR carriers, are inefficient and redundant, particularly in in-band and guard-band operations, as they require redundant signaling and do not effectively handle frequency shifts between DL and UL PRB centers.
Innovation Solution
The proposed solution involves NB-IoT devices inferring or retrieving the DL-to-UL frequency offset from the raster offset signaled in the Narrowband Master Information Block (MIB-NB), allowing for reduced signaling and enabling efficient deployment within LTE and NR carriers by configuring the NB-IoT carrier in a New Radio (NR) carrier and transmitting an indication of the frequency offset to be applied.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If NB-IoT devices use existing methods to determine DL-to-UL frequency offset in TDD networks deployed inside LTE or NR carriers, then frequency offset determination is achieved, but signaling overhead increases and redundancy occurs
Solution Approach 1:
The patent enables NB-IoT devices to autonomously determine the DL-to-UL frequency offset by utilizing the raster offset value already signaled in MIB-NB. The device calculates the frequency offset based on the relationship between DL and UL PRB centers and the indicated raster offset, eliminating the need for separate network signaling and reducing redundancy while maintaining determination accuracy
Solution Approach 2:
The patent changes the approach from direct signaling of frequency offset to signaling of raster offset, which then serves as a basis for device calculation. This parameter transformation reduces signaling overhead while enabling the device to derive the necessary frequency offset information through computational relationships between DL/UL PRB centers and raster offset
2Adaptability or versatility
If NB-IoT TDD is deployed in in-band or guard-band modes inside LTE carriers, then carrier deployment flexibility improves, but frequency alignment between DL and UL becomes complex due to half-tone shift
Solution Approach 1:
The patent introduces the raster offset as an intermediary parameter that mediates between the DL and UL frequency domains. By signaling the raster offset and enabling devices to calculate frequency offsets based on PRB center relationships, it simplifies the frequency alignment process while maintaining support for in-band and guard-band deployment modes within LTE and NR carriers
Solution Approach 2:
The patent segments the frequency offset determination into distinct components: the raster offset signaled by the network and the device-calculated offset based on PRB center relationships. This segmentation allows independent optimization of signaling and calculation processes, reducing overall system complexity while supporting flexible carrier deployment
Data Source
AI summary
Methods and apparatuses are disclosed for communicating to a wireless device (WD) a DL-to-UL frequency offset (or frequency shift) that may need to be applied. For example, a method implemented in a wireless device (WD) is provided. The method comprises: receiving, from the network node, an indication of a frequency offset; and applying the received frequency offset; wherein the WD is configured to operate on a narrow-band Internet of Things (NB-IoT) carrier in a New Radio (NR) carrier.