User-Dedicated Pilot Signal Configuration for LTE NCT Channel Estimation
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Solution Overview
Problem
In the LTE R11 system, the existing dedicated pilot design is not adaptable to the new carrier type (NCT), leading to poor channel estimation quality and communication data demodulation performance for user equipment, as there is no reference signal for signal demodulation in special frames and inadequate pilot distribution in normal subframes.
Innovation Solution
A method for transmitting a user-dedicated pilot signal, where the first five OFDM symbols of a time slot in a physical resource block pair carry all resource elements for the pilot signal, with specific configurations for different subframes and cyclic prefixes, ensuring adequate pilot distribution across subcarriers and symbols to support demodulation, including configurations for multiple antenna ports and code division multiplexing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the existing dedicated pilot design is used in LTE R11 NCT, then the system structure is simplified, but the channel estimation quality deteriorates
Solution Approach 1:
The patent segments the time-frequency resources by dividing the subframe into specific time slots and frequency subcarriers, with dedicated pilot signals placed in the first time slot at specific frequency positions. This segmentation ensures that pilot signals are distributed across different resource elements, providing sufficient reference signals for channel estimation while maintaining the simplified NCT structure without CRS.
Solution Approach 2:
The patent applies local quality by concentrating dedicated pilot signals in specific local regions of the time-frequency grid (first time slot, specific subcarriers) rather than uniform distribution. This localized placement optimizes channel estimation quality in critical regions while allowing other regions to be used for data transmission, resolving the contradiction between structure simplification and estimation quality.
2Device complexity
If dedicated pilot is provided only in the last two symbols of the first time slot, then the resource allocation is simplified, but the demodulation performance deteriorates
Solution Approach 1:
The patent extends pilot signal placement from a single time slot to multiple time slots (first and second time slots), adding a temporal dimension to pilot distribution. This multi-time-slot placement ensures that pilots are available across the entire subframe duration, improving demodulation reliability for data transmitted in both time slots while maintaining simplified resource allocation rules.
Solution Approach 2:
The patent places dedicated pilot signals in the first time slot before data transmission occurs in both the first and second time slots. This preliminary placement of pilots in the first time slot allows the receiver to perform channel estimation early, which then can be used for demodulating data in subsequent time slots, improving overall demodulation performance.
3Productivity
If no reference signal is provided in special frames, then the resource usage is optimized, but the signal demodulation becomes impossible
Solution Approach 1:
The patent makes the dedicated pilot signal universal by using the same pilot structure and resource allocation mechanism for both normal subframes and special frames in NCT. The dedicated pilot serves multiple functions: it enables channel estimation for data demodulation in normal subframes, and it provides the necessary reference signal for demodulating special frames that previously had no reference signals, thus optimizing resource usage while ensuring demodulation capability across all frame types.
Data Source
AI summary
Embodiments of the present application provide a method for transmitting a pilot signal, a method for receiving a pilot signal, a base station, and a user equipment. The method for transmitting the pilot signal includes: determining a physical resource block pair which is used for carrying a user-dedicated pilot signal, where first five orthogonal frequency division multiplexing (OFDM) symbols in a first time slot of the physical resource block pair include all resource elements used for carrying the user-dedicated pilot signal; and transmitting the physical resource block pair which is used for carrying the user-dedicated pilot signal. The method for transmitting the pilot signal, the method for receiving the pilot signal, the base station, and the user equipment according to embodiments of the present application can improve communication data demodulation performance of a user equipment.