Relay Node Reference Signal Transmission for LTE Channel Estimation
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Solution Overview
Problem
Current wireless telecommunications systems face challenges in providing relay transparency and efficient reference signal transmission schemes for channel estimation and mobility measurements in LTE and LTE-A networks, particularly due to technical difficulties in simultaneous signal transmission and reception by relay nodes.
Innovation Solution
The system configures relay nodes to support multiple reference signal transmission schemes, including common reference signals (CRS) and dedicated reference signals (DRS) for channel estimation and mobility measurements, and uses adaptive procedures to reconfigure multicast/broadcast single frequency network subframes for improved spectral efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If relay nodes transmit common reference signals (CRS) simultaneously with access nodes, then channel estimation accuracy improves, but signal interference and transmission complexity increase
Solution Approach 1:
The patent segments reference signal transmission by introducing two distinct types: CRS transmitted by access nodes and DRS transmitted by relay nodes. This segmentation allows each node type to transmit reference signals independently without requiring simultaneous coordinated transmission, thereby maintaining channel estimation accuracy while reducing transmission complexity and interference management overhead.
Solution Approach 2:
The patent introduces DRS as an intermediary reference signal specifically for relay nodes. This intermediary signal enables relay nodes to provide channel estimation functionality without directly interfering with the CRS transmission from access nodes, thus resolving the contradiction between improving measurement precision and reducing device complexity.
2Reliability
If relay nodes use dedicated reference signals (DRS) for channel estimation, then transmission reliability improves, but spectral efficiency decreases
Solution Approach 1:
The patent implements dynamic reference signal transmission where relay nodes transmit DRS only in specific subframes configured by the access node, rather than continuously. This dynamic approach ensures reliable channel estimation when needed while minimizing spectral resource consumption, thereby balancing transmission reliability with spectral efficiency.
Solution Approach 2:
The patent employs periodic DRS transmission patterns configured by the access node, where relay nodes transmit DRS at scheduled intervals rather than continuously. This periodic action maintains transmission reliability for channel estimation while significantly improving spectral efficiency by avoiding redundant reference signal transmissions.
3Speed
If relay nodes transmit reference signals at higher data rates, then communication speed improves, but power consumption increases
Solution Approach 1:
The patent implements periodic reference signal transmission where relay nodes transmit DRS only in specifically configured subframes rather than continuously. This allows the relay node to achieve necessary communication speed for channel estimation while significantly reducing power consumption by remaining in a low-power state during non-transmission periods.
Solution Approach 2:
The patent creates an inert transmission environment by configuring relay nodes to transmit reference signals only when explicitly scheduled by the access node. This inert approach minimizes unnecessary transmissions and power consumption while maintaining adequate communication speed for reliable channel estimation and mobility measurements.
Data Source
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AI summary
A network comprising a relay node configured to transmit a first common reference signal (CRS) to a plurality of user agents (UAs) using a first plurality of physical antennas and/or virtual antennas, and an access node configured to transmit a second CRS to the UAs using a second plurality of physical antennas and/or virtual antennas, wherein the first CRS and the second CRS are combined for the same number of first and second physical antennas and/or virtual antennas. Included is a network comprising a relay node configured to transmit a dedicated reference signal (DRS) to a UA using a first plurality of physical antennas and/or virtual antennas, and an access node configured to transmit a second DRS to the UA using a second plurality of physical antennas and/or virtual antennas, wherein the first DRS and the second DRS are transmitted at about the same time.