DMRS Power Control for Interference Measurement in LTE
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Solution Overview
Problem
In LTE and LTE-A systems, accurate interference measurement is necessary for effective interference management, but existing methods are inadequate, leading to suboptimal performance due to inaccurate interference estimation and overlapping reference signals in distributed antenna systems.
Innovation Solution
The method involves transmitting control information from an eNB to a UE, including configuration and transmission power control information for DeModulation Reference Signals (DMRS), enabling the UE to estimate interference signals accurately and improve reception capability by distinguishing between dominant and non-dominant interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If MU-MIMO transmission is used to transmit wireless signals to multiple UEs using identical time and frequency resources, then system capacity is improved, but interference occurs between wireless signals for different receivers
Solution Approach 1:
The patent segments the reference signal resources by assigning different cyclic shifts and orthogonal cover codes to different UEs. This segmentation allows multiple UEs to receive signals simultaneously on the same time-frequency resources while maintaining distinguishable reference signals, thereby enabling MU-MIMO operation with reduced interference.
Solution Approach 2:
The patent introduces additional dimensions for reference signal differentiation beyond basic frequency-time resources. By utilizing cyclic shifts and orthogonal cover codes as additional dimensions, the system can support multiple UEs on identical time-frequency resources, effectively resolving the interference problem while maintaining high system capacity.
2Productivity
If reference signals for multiple UEs are transmitted on identical time and frequency resources in MU-MIMO, then resource efficiency is improved, but reference signals overlap and cause interference
Solution Approach 1:
The patent applies local quality by giving each UE's reference signal unique local characteristics through specific cyclic shifts and orthogonal cover codes. This allows the reference signals to be locally distinguishable at each UE's receiver, enabling accurate channel estimation and interference measurement even when transmitted on identical resources.
Solution Approach 2:
The patent performs preliminary configuration of cyclic shifts and orthogonal cover codes for each UE before actual data transmission. This preliminary assignment ensures that reference signals are pre-differentiated, allowing UEs to accurately measure and manage interference from other UEs' signals without confusion.
3Adaptability or versatility
If a UE attempts to measure interference from dominant interferers without proper control information, then interference management capability is improved, but measurement accuracy deteriorates due to lack of transmission power information
Solution Approach 1:
The patent implements feedback by providing control information from the network to the UE regarding the transmission power of dominant interferers' reference signals. This feedback enables the UE to accurately measure and compensate for interference, significantly improving both interference management capability and measurement precision.
Solution Approach 2:
The patent introduces control information as an intermediary that carries transmission power information about dominant interferers. This intermediary enables the UE to bridge the gap between raw signal measurements and accurate interference characterization, allowing for precise interference management.
Data Source
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AI summary
A method and apparatus for transmitting control information to a User Equipment (UE) by an evolved Node B (eNB) for interference measurement in a wireless communication system are provided. The eNB determines whether the UE can perform interference management for receiving a data signal transmitted from the eNB based on information of an interference signal. When it is determined that the UE can perform the interference management, the eNB transmits to the UE configuration information for receiving the data signal by applying the interference management by the UE, and then transmits to the UE downlink control information including transmission power control information indicating whether a transmission power of a DeModulation Reference Signal (DMRS) corresponding to the interference signal is different from a transmission power of the interference signal.