NR Resource Block Grid Alignment With LTE Coexistence
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Solution Overview
Problem
The coexistence of LTE and NR systems in the same frequency band leads to RB grid mismatch issues due to differences in DC subcarrier handling methods, causing interference and inefficiencies in resource operation.
Innovation Solution
A method is proposed to address RB grid mismatch by implementing a shift operation in the NR system to align its RB grid with that of the LTE system, using a 7.5 kHz shift in subcarrier spacing, and employing precoder/beam cycling technology with scalable granularity and OCC to minimize interference and enhance link reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NR system uses its own RB grid structure with different DC subcarrier handling, then NR system achieves its performance targets, but RB grid mismatch occurs with LTE system causing interference
Solution Approach 1:
The patent applies parameter changes by adjusting the subcarrier spacing of the NR system by 7.5 kHz to align its RB grid with the LTE system. This parameter adjustment resolves the grid mismatch issue while maintaining NR performance requirements, thereby reducing interference between the two systems operating in the same frequency band.
2Object-affected harmful factors
If NR system aligns RB grid with LTE system by shifting subcarrier spacing, then interference is reduced, but NR system must deviate from its original design parameters
Solution Approach 1:
The patent implements dynamics by introducing a shift indicator that dynamically controls the 7.5 kHz subcarrier spacing adjustment in the NR system. This allows the system to adaptively align or misalign RB grids based on whether LTE coexistence is detected, providing operational flexibility while resolving interference issues when needed.
Solution Approach 2:
The patent applies preliminary action by configuring the shift indicator in advance through system information or RRC signaling before NR data transmission begins. This preliminary configuration ensures that the NR system is pre-aligned with the LTE RB grid structure, preventing interference from the outset rather than correcting it afterward.
3Reliability
If precoder/beam cycling is implemented with fine granularity, then link reliability for high mobility terminals is improved, but system complexity increases
Solution Approach 1:
The patent applies partial action by implementing precoder/beam cycling selectively based on terminal mobility characteristics. The system uses the shift indicator mechanism to enable or disable fine-granularity precoder cycling only when necessary for high mobility terminals, rather than applying it universally, thus improving reliability while controlling system complexity.
Data Source
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AI summary
A method performed by a user equipment, UE, in a communication system, the method comprising: receiving, from a base station, a system information block, SIB; in a case that the SIB includes an indication indicating to shift first resource blocks, RBs, for a new radio, NR, system by a certain frequency value, shifting the first RBs by the certain frequency value to align a grid of the first RBs with a grid of second RBs for a long term evolution, LTE, system; and transmitting, to the base station, an uplink signal on the first RBs shifted by the certain frequency value, wherein the certain frequency value is 7.5kHz.