Coordinated Multipoint Demodulation Reference Signal Orthogonality
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Solution Overview
Problem
In LTE networks, antenna ports at different locations do not meet quasi-co-location requirements, leading to damaged DM-RS orthogonality, reduced channel estimation precision, and impaired demodulation performance, preventing simultaneous data transmission from different network side devices to the same user equipment.
Innovation Solution
A coordinated multipoint transmission/reception method where user equipment receives data and demodulation reference signals from multiple network side devices using different antenna ports, with independent frequency offset compensation to ensure orthogonality, even when signals have different frequency offsets, by occupying distinct time-frequency resources and performing joint demodulation processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If antenna ports at different locations are used for coordinated multipoint transmission, then the coverage area and data transmission capability are improved, but the DM-RS orthogonality is damaged and channel estimation precision deteriorates
Solution Approach 1:
The patent divides the antenna ports into different groups (first antenna port group and second antenna port group) with different DM-RS configurations. Each group uses distinct time-frequency resources or orthogonal codes, allowing simultaneous transmission from multiple network side devices without DM-RS interference, thus maintaining channel estimation precision while expanding coverage area.
Solution Approach 2:
The patent introduces additional dimensions for DM-RS differentiation beyond traditional spatial separation. By using different time slots, frequency resources, or orthogonal codes for DM-RS from different network side devices, the system enables multipoint transmission while preserving orthogonality and channel estimation accuracy.
2Productivity
If multiple network side devices transmit data simultaneously to the same user equipment, then the data transmission rate is improved, but the demodulation performance deteriorates due to frequency offsets
Solution Approach 1:
The patent applies different DM-RS configurations to different antenna port groups based on their specific characteristics. Each network side device's antenna ports are configured with appropriate time-frequency resources or orthogonal codes tailored to their frequency offsets, enabling simultaneous high-rate transmission while maintaining reliable demodulation for each device.
3Productivity
If antenna ports use the same time-frequency resources for DM-RS transmission, then the resource utilization is improved, but the DM-RS orthogonality is damaged when signals have different frequency offsets
Solution Approach 1:
The patent dynamically allocates DM-RS time-frequency resources based on the frequency offsets and channel conditions of different network side devices. When frequency offsets are present, the system adjusts resource allocation to maintain orthogonality; when conditions permit, it consolidates resources to improve utilization efficiency.
Data Source
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AI summary
This application relates to a data transmission method, user equipment, and a network side device. The method includes: receiving, in a subframe, first data and first demodulation reference signal(s) that are sent by a first network side device by using n antenna port(s), and second data and second demodulation reference signal(s) that are sent by a second network side device by using m antenna port(s), where time-frequency resources occupied by the first demodulation reference signal(s) are different from time-frequency resources occupied by the second demodulation reference signal(s), and a time-frequency resource occupied by the first data and that occupied by the second data at least partly overlap; and performing demodulation processing on the data based on the first demodulation reference signal(s) and the second demodulation reference signal(s). The data transmission method, the user equipment, and the network side device in this application may be applied to coordinated multipoint transmission/reception in which a plurality of network side devices that are not quasi-co-located simultaneously send data to user equipment, so that orthogonality between demodulation reference signal(s) from the plurality of network side devices can be ensured.