Carrier Raster Decoupling for Flexible RF Placement
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Solution Overview
Problem
The existing wireless communication networks face limitations in carrier placement due to the restriction that RF carriers must be aligned with both the carrier raster and subcarrier grid, leading to reduced flexibility in selecting subcarrier spacing and resulting in unused gaps between component carriers during carrier aggregation.
Innovation Solution
Decoupling the carrier raster from the subcarrier grid by defining carrier positions based on a carrier raster and mapping them to a common subcarrier grid, allowing for greater flexibility in placing RF carriers and minimizing the distance between component carrier positions, which are not limited to the least common multiple of carrier and subcarrier spacings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If RF carriers are aligned with both carrier raster and subcarrier grid, then carrier placement is standardized and cell search is simplified, but flexibility in selecting subcarrier spacing is reduced and unused gaps appear between component carriers
Solution Approach 1:
The patent separates the carrier raster alignment function from the subcarrier grid alignment function. The carrier raster defines coarse frequency positions for cell search, while the subcarrier grid independently defines precise subcarrier positions. This segmentation allows each grid to operate independently, resolving the contradiction between simplified cell search and flexible carrier placement.
Solution Approach 2:
The patent introduces an intermediary mapping relationship between carrier raster positions and subcarrier grid positions. The carrier indicator (CI) and subcarrier grid offset (K) act as mediators that translate between the two grids, enabling flexible carrier placement while maintaining standardized cell search procedures based on the carrier raster.
2Stability of the object's composition
If carrier positions are restricted to least common multiple of carrier and subcarrier spacings, then grid alignment is maintained, but spectrum usage efficiency decreases due to reserved subcarriers
Solution Approach 1:
The patent divides the frequency domain into two independent grid systems: the carrier raster for carrier positioning and the subcarrier grid for subcarrier positioning. By segmenting these functions, the system eliminates the need to align to the least common multiple of both spacings, thereby eliminating reserved subcarriers and improving spectrum usage efficiency while maintaining grid alignment through independent subcarrier grid definition.
3Productivity
If multiple component carriers are aggregated, then throughput is increased, but placement flexibility is reduced due to alignment constraints
Solution Approach 1:
The patent segments the carrier aggregation function from the grid alignment constraints by introducing independent subcarrier grids for each component carrier. Each component carrier can be placed flexibly based on spectrum availability while maintaining its own subcarrier grid alignment, enabling carrier aggregation with high placement flexibility and optimal throughput.
Data Source
AI summary
Teachings herein improve the choice of carrier placement in a wireless communication network by de-coupling the carrier raster from the subcarrier grid. Recognizing that the placement of a carrier by its center frequency is an artificial construct, it is re-defined and the carrier placement is instead defined by the carrier position, which is on a carrier raster (e.g., 100 kHz), but in general does not have to be the center of the carrier. Second, a subcarrier grid is defined that is common for all RF carriers and spanning a range of frequencies, at least within an operating band, and provides orthogonality for subcarriers within all RF carriers regardless of carrier position. Third, a unique mapping from the carrier position on the RF carrier raster to a subcarrier reference position, e.g., the DC subcarrier, is defined, which in turn identifies the exact position of the RF carrier on the subcarrier grid.