Phase Synchronization for CoMP Joint Transmission
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Solution Overview
Problem
In wireless communication networks, especially in CoMP systems, phase synchronization across multiple base stations is challenging due to phase drift, which degrades performance and interferes with coordinated multipoint transmissions.
Innovation Solution
The method involves a UE-assisted phase synchronization technique where UEs compute and report wideband co-phasing values and slope values based on downlink and uplink phase synchronization reference signals (PSRS) received from multiple base stations, allowing base stations to calculate timing differences and apply phase correction values to improve synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phase synchronization reference signals are used for CoMP joint transmission, then phase coherence between base stations is improved, but phase drift still degrades performance
Solution Approach 1:
The patent implements a feedback mechanism where UEs report wideband co-phasing values and slope values to base stations. The base station uses this feedback to calculate timing differences and apply phase correction values, creating a closed-loop system that continuously compensates for phase drift and maintains synchronization accuracy.
Solution Approach 2:
The patent replaces traditional mechanical or hardware-based phase synchronization methods with a signal processing approach. By using PSRS, computing co-phasing values, and applying digital phase corrections based on UE feedback, the system achieves synchronization through software-based signal manipulation rather than physical timing mechanisms.
2Measurement precision
If per-tone co-phasing values are computed for each tone over the whole spectrum band, then phase synchronization precision is improved, but computational complexity increases
Solution Approach 1:
The patent segments the frequency spectrum into multiple tones and computes co-phasing values for each tone individually. This segmentation allows precise phase measurement across the entire bandwidth while managing computational complexity by processing each tone separately rather than handling the entire spectrum as a single complex signal.
Solution Approach 2:
The patent computes co-phasing values for all tones across the whole spectrum band, which may be more detailed than strictly necessary. This excessive action ensures maximum synchronization precision by capturing phase variations at every frequency point, even though it increases computational requirements.
3Measurement precision
If timing difference is determined based on slope value difference, then phase correction accuracy is improved, but feedback overhead from UE increases
Solution Approach 1:
The patent transforms the raw co-phasing measurements into derived parameters: wideband co-phasing values and slope values. By computing timing differences from the difference in slope values rather than raw measurements, the system achieves accurate timing synchronization while condensing information into compact feedback parameters that reduce overhead.
Solution Approach 2:
The patent introduces slope values as intermediary parameters between raw co-phasing measurements and timing difference calculations. These slope values serve as a compressed representation that captures essential timing information while reducing the amount of data that needs to be fed back from UEs to base stations.
Data Source
AI summary
Over-the-air phase synchronization for reciprocity-based coordinated multipoint (CoMP) joint transmission is discussed. The base stations of the CoMP group and served user equipment (UEs) transmit phase synchronization reference signals (PSRS). The receiving nodes compute wideband co-phasing values representing the phase difference between pairs of the PSRS over each tone of a whole spectrum band, and slope values based on the per-tone co-phasing values. The UEs feedback the wideband downlink co-phasing value and the downlink slope value. The base stations of the CoMP group determine a phase compensation based on the differences between the slope value calculated by the base station and the slope value reported by the UE, and based on the differences between the wideband co-phasing value calculated by the base station and the wideband co-phasing value reported by the UE. The base station uses the phase compensation to adjust communications by the base stations in the CoMP group.