Common Phase Error Reference Signal Multiplexing
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Solution Overview
Problem
In wireless communication networks, especially in LTE-NX systems, the removal of always-on signals simplifies time-frequency synchronization but complicates tracking and fine adjustments, leading to inefficient common phase error tracking due to high overhead and interference, and conventional solutions like DMRS are not effective for accurate phase error compensation.
Innovation Solution
A common phase error reference signal (CPE-RS) is generated from the effective transmitted DMRS using an orthogonal cover code structure for code multiplexing, allowing for separate phase error compensation and improved resource utilization without limiting the number of DMRS layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional DMRS is used for phase error compensation, then demodulation reference signal functionality is provided, but phase error tracking accuracy is insufficient and overhead is high
Solution Approach 1:
The patent segments the reference signal functionality by introducing a separate CPE-RS specifically dedicated to common phase error tracking, distinct from the DMRS used for demodulation. This segmentation allows CPE-RS to be optimized for phase tracking without being constrained by DMRS design requirements, thereby improving phase error tracking accuracy while managing overhead efficiently through dedicated resource allocation for CPE-RS
Solution Approach 2:
The patent implements multi-functionality by designing CPE-RS to serve dual purposes: it provides common phase error tracking and simultaneously supports multi-user MIMO operations. The CPE-RS can be configured to be orthogonal to DMRS layers, enabling it to function as both a phase reference signal and a reference signal for additional user layers, thereby improving resource utilization without increasing overall overhead
2Measurement precision
If CPE-RS is introduced for accurate phase tracking, then phase error compensation is improved, but resource utilization and configuration flexibility are reduced
Solution Approach 1:
The patent applies dynamics by making CPE-RS configuration flexible and adaptable through higher-layer signaling. The CPE-RS can be dynamically configured with different parameters including resource element positions, orthogonality relationships with DMRS layers, and activation/deactivation states. This dynamic configuration capability allows the system to adapt CPE-RS to different deployment scenarios and traffic conditions while maintaining accurate phase tracking
Solution Approach 2:
The patent enables parameter changes by allowing CPE-RS characteristics to be modified through signaling configurations. Key parameters such as the number of CPE-RS ports, their mapping to physical resources, and their orthogonality relationships can be changed based on network conditions and service requirements. This parameter flexibility ensures that phase tracking accuracy is maintained while adapting to different system configurations and avoiding resource conflicts
3Quantity of substance
If CPE-RS uses same resources as DMRS, then resource efficiency is improved, but interference and tracking accuracy are degraded
Solution Approach 1:
The patent applies local quality by creating different orthogonality relationships between CPE-RS and DMRS based on local conditions. Specifically, CPE-RS can be configured to be orthogonal to certain DMRS layers while non-orthogonal to others, depending on which layers are active and their spatial relationships. This localized orthogonality configuration allows CPE-RS to avoid interference with specific DMRS layers while maintaining resource efficiency, thereby preserving phase tracking accuracy without requiring complete resource separation
Data Source
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AI summary
According to some embodiments, a method in a wireless receiver of compensating common phase error in a received wireless signal comprises receiving a first symbol of a wireless signal. The first symbol comprises a code division multiplexed demodulation reference signal (DM-RS) multiplexed with a length M orthogonal cover code, and a first code division multiplexed common phase error reference signal (CPE-RS) multiplexed with a length N orthogonal cover code, wherein N is less than or equal to M. The method further comprises determining M code points in the first symbol associated with a DM-RS; estimating a channel corresponding to the received wireless signal using the M code points associated with the DM-RS; estimating a first CPE-RS corresponding to the estimated channel using the first N code points of the M code points associated with the DM-RS; and compensating the estimated channel for phase error using the estimated first CPE-RS.