CoMP UE Zero-Power CSI-RS Rate Matching
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Solution Overview
Problem
In cooperative multi-point (CoMP) wireless communication systems, user equipment (UE) faces challenges in receiving data accurately when downlink control information does not indicate the transmitting base station, particularly in managing zero-power channel state information-reference signals (CSI-RS) to avoid interference and ensure effective data reception.
Innovation Solution
The method involves receiving downlink control information that lacks transmission base station information, assuming data is not mapped to the resource element of the zero-power CSI-RS with the lowest index, and using interference measurement resources (IMRs) to measure interference, allowing the UE to receive data through the physical downlink control channel (PDSCH) by assuming data is mapped in remaining IMRs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the UE receives downlink control information without transmission base station information in CoMP systems, then the system complexity is reduced and ease of operation is improved, but data reception reliability deteriorates due to uncertainty about the actual transmitting base station
Solution Approach 1:
The UE performs preliminary rate matching by assuming data is not mapped to zero-power CSI-RS resource elements before actual data reception. This preliminary action prepares the UE to handle interference from multiple base stations by pre-identifying resource elements that should be excluded from data mapping, thereby improving data reception reliability without requiring explicit transmission base station information in the downlink control information
Solution Approach 2:
Zero-power CSI-RS resource elements serve as an intermediary mechanism to indicate resource allocation patterns without explicitly signaling which base station transmits data. By using these specialized reference signal resources, the system conveys necessary timing and frequency location information for rate matching while maintaining simplified downlink control information structure, thus resolving the contradiction between operational simplicity and reception reliability
2Measurement precision
If the UE assumes data is not mapped to zero-power CSI-RS resource elements for rate matching, then data reception accuracy is improved, but resource utilization efficiency worsens due to potential waste of resource elements
Solution Approach 1:
The UE applies rate matching assumptions selectively to specific zero-power CSI-RS resource elements rather than uniformly to all resource elements. By identifying the lowest indexed zero-power CSI-RS resource and applying rate matching only to those specific resource elements, the system maintains high data reception accuracy while minimizing resource waste, as other resource elements can still be utilized for data transmission
Solution Approach 2:
The system uses a conservative approach by assuming data is not mapped to zero-power CSI-RS resource elements with the lowest index, which may result in some resource elements being left unused. This partial action ensures data reception accuracy is maintained even if it means sacrificing some resource utilization efficiency, particularly in scenarios where interference coordination is critical
Data Source
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AI summary
The present invention relates to a wireless communication system. A method for receiving data by a user equipment (UE) in a cooperative multi-point (CoMP) wireless communication system includes receiving downlink control information (DCI) that does not contain information indicating a transmission base station (BS) that actually transmits data among a plurality of BSs that participate in CoMP, receiving information about zero-power channel state information-reference signal (CSI-RS) of each of the plural BSs, and assuming that data is not mapped to a resource element of zero-power CSI-RS with a lowest index and receiving the data through a physical downlink control channel (PDSCH).