CoMP Receiver Timing Adjustment via Composite Reference Signals
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Solution Overview
Problem
In Coordinated MultiPoint (CoMP) systems, timing synchronization in downlink transmissions is challenging due to propagation delays and varying signal strengths from macro and low power nodes, leading to inter-carrier interference (ICI) and inter-symbol interference (ISI) in wireless devices, as traditional synchronization methods using primary synchronization signals (PSS) and cell-specific reference signals (CRS) may not accurately account for signals from multiple geographically dispersed transmission points.
Innovation Solution
The solution involves adjusting the receiver timing of wireless devices using composite received reference signal timing calculated from node-specific reference signals, such as channel-state information reference signals (CSI-RS), which considers the earliest or weighted average of received signal timings from multiple cooperating nodes to align with the strongest signal power, thereby reducing ICI and ISI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional synchronization methods using PSS and CRS are used, then the system is simple to implement, but timing synchronization accuracy deteriorates in CoMP systems with multiple geographically dispersed transmission points
Solution Approach 1:
The patent changes the parameter used for timing synchronization from traditional PSS/CRS signals to node-specific reference signals (such as CSI-RS). This parameter change enables accurate timing estimation for each individual transmission point in CoMP systems, resolving the contradiction by improving measurement precision while managing complexity through targeted signal usage.
Solution Approach 2:
The patent segments the synchronization process by using separate node-specific reference signals for each transmission point rather than a single unified synchronization signal. This allows independent timing estimation for each node, improving overall synchronization accuracy in multi-point systems while maintaining manageable complexity through modular signal processing.
2Measurement precision
If receiver timing is adjusted based on composite received reference signal timing from multiple nodes, then timing synchronization accuracy improves, but signal processing complexity increases
Solution Approach 1:
The patent implements feedback mechanisms where the wireless device measures received reference signal timings from multiple nodes and feeds back timing information to the network. The network then adjusts transmission timing based on this feedback, creating a closed-loop system that improves timing accuracy while distributing processing complexity between the device and network infrastructure.
Solution Approach 2:
The patent applies partial action by using only the necessary subset of reference signals from multiple nodes rather than processing all possible signals. The receiver timing is adjusted based on composite timing from selected nodes, providing sufficient synchronization accuracy without the full complexity of processing every available signal path.
3Measurement precision
If node-specific reference signals are used for timing estimation, then timing accuracy for each transmission point improves, but the number of reference signals to process increases
Solution Approach 1:
The patent makes reference signals multi-functional by using node-specific reference signals (such as CSI-RS) that serve both channel state information acquisition and timing synchronization purposes. This universality allows the system to obtain timing estimation accuracy for each transmission point without proportionally increasing the total number of reference signals, as the same signals fulfill multiple functions.
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AI summary
Technology for adjusting a receiver timing of a wireless device in a Coordinated Multipoint (CoMP) system is disclosed. One method can include the wireless device receiving a plurality of node specific reference signals (RSs) from a plurality of cooperating nodes in a coordination set of the CoMP system. The coordination set includes at least two cooperating nodes. The wireless device can estimate a composite received RS timing from a plurality of received RS timings generated from the plurality of node specific RSs. The received RS timings represent timings from the at least two cooperating nodes. The wireless device can adjust the receiver timing based on the composite received RS timing. A node specific RS can include a channel-state information reference signal (CSI-RS).