NB-IoT Uplink Reference Signal Mapping for Dynamic Scheduling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The NB-IoT system requires a different reference signal allocation method due to its dynamic scheduling in subcarrier units, which differs from the fixed pattern in existing LTE systems, necessitating a new approach for uplink reference signal transmission.
Innovation Solution
A method and device for transmitting an uplink reference signal in an NB-IoT system, involving the generation and mapping of the signal across scheduled resource elements, using a physical cell identifier, and employing demodulation reference signals (DMRS) with specific slot and subcarrier allocations, including the use of constant amplitude zero auto-correlation (CAZAC) sequences and pseudo-noise (PN) properties for orthogonality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed pattern reference signal allocation method from LTE system is used, then channel estimation can be performed, but it cannot adapt to dynamic scheduling in subcarrier units of NB-IoT system
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed reference signal allocation pattern to a dynamic allocation method that adapts to NB-IoT's subcarrier-unit scheduling. The reference signal is allocated based on the actual scheduled resource blocks in units of subcarriers, allowing the allocation pattern to change dynamically according to scheduling decisions rather than following a predetermined fixed pattern.
Solution Approach 2:
The patent changes the allocation parameters by defining reference signal resources based on the number of scheduled resource blocks and the subcarrier spacing. The allocation pattern varies according to parameters such as the number of contiguous resource blocks, the subcarrier spacing factor, and the physical cell identifier, enabling adaptation to different scheduling scenarios without requiring a completely new allocation methodology.
2Reliability
If reference signal is allocated across multiple slots and subcarriers, then coverage is improved, but mapping complexity increases
Solution Approach 1:
The patent segments the reference signal allocation into discrete resource elements within scheduled resource blocks, assigning specific reference signal resources to each resource block based on its position and size. This segmentation allows the complex multi-slot and multi-subcarrier allocation to be broken down into manageable units that can be processed systematically through the mapping procedure.
Solution Approach 2:
The patent introduces a systematic mapping approach that transitions from two-dimensional resource allocation (slots and subcarriers) to a one-dimensional sequence-based mapping process. By generating a base sequence and mapping it sequentially through the resource elements in a defined order, the complexity of multi-dimensional allocation is simplified into a linear processing sequence that is easier to implement.
Data Source
AI summary
In a system supporting narrowband Internet of things (NB-IoT), a terminal maps an uplink reference signal to a plurality of resource elements in a scheduled resource allocation unit, and transmits the uplink reference signal mapped to the plurality of resource elements. Here, the scheduled resource allocation unit includes a first number of contiguous slots in a time domain and a second number of contiguous subcarriers in a frequency domain.