MIMO Precoding for Distributed Antenna Systems
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Solution Overview
Problem
Existing MIMO precoding schemes are inadequate for Distributed Antenna System (DAS) channel environments, which require a new scheme to effectively manage correlated and uncorrelated channel conditions for efficient downlink data transmission.
Innovation Solution
A method and apparatus for determining active antenna ports and assigning a Multiple-Input and Multiple-Output (MIMO) mode to User Equipment (UE), using feedback information to determine a signal precoding vector and precoding signals for transmission through active antenna ports, optimizing MIMO transmission for DAS downlink channel properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing MIMO precoding schemes are used in DAS channel environments, then the system can operate with standard protocols, but the transmission efficiency and data rate are insufficient due to inadequate handling of correlated and uncorrelated channel conditions
Solution Approach 1:
The patent changes the precoding parameters by introducing a codebook specifically designed for DAS channel environments. The codebook contains precoding vectors that account for the unique correlated and uncorrelated channel conditions in DAS, allowing the system to adapt to DAS-specific channel properties while maintaining standard MIMO operation protocols
Solution Approach 2:
The patent segments the precoding process into two distinct parts: intra-DAP precoding (handling correlated channels within the same DAP) and inter-DAP precoding (handling uncorrelated channels between different DAPs). This segmentation allows each part to be optimized for its specific channel characteristics, improving overall transmission efficiency
2Productivity
If a new MIMO precoding scheme is developed specifically for DAS channel environments, then transmission efficiency improves, but system complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing optimal precoding vectors in a codebook during system setup. These vectors are computed in advance based on typical DAS channel conditions, so that during actual operation, the base station only needs to select from the pre-computed codebook rather than performing complex real-time calculations, thus reducing operational complexity
Solution Approach 2:
The patent implements a feedback mechanism where the UE provides channel state information and precoding matrix indicator (PMI) feedback to the base station. This feedback allows the base station to adaptively select the most appropriate precoding vector from the codebook based on current channel conditions, optimizing data transmission rate without requiring the base station to perform complex real-time precoding calculations
3Productivity
If distributed antennas are used to provide macroscopic diversity and reduce inter-cell interference, then system capacity increases, but the channel environment becomes more complex with both correlated and uncorrelated paths
Solution Approach 1:
The patent segments the channel measurement and detection process into two parts: measuring correlated channels within each DAP and measuring uncorrelated channels between different DAPs. This segmentation simplifies the overall measurement task by breaking it into manageable components that can be handled separately, making the complex DAS channel environment more tractable
Solution Approach 2:
The patent changes the measurement parameters by introducing separate measurement procedures for intra-DAP and inter-DAP channels. The system measures channel state information and calculates correlation coefficients differently for correlated versus uncorrelated paths, allowing the complex DAS channel environment to be characterized and managed through distinct measurement parameters
Data Source
AI summary
A transmission method and apparatus utilizing Multiple-Input and Multiple-Output (MIMO) precoding based on Distributed Antenna Systems (DASs) are provided. The transmission method includes determining active antenna ports, for a User Equipment (UE) having multiple receive antennas, from among a plurality of Distributed Antenna Ports (DAPs) evenly placed in a service area; assigning a Multiple-Input and Multiple-Output (MIMO) mode to the UE and notifying the UE of the MIMO mode assignment; determining a signal precoding vector on a basis of feedback information for the MIMO mode received from the UE; and precoding a signal using the signal precoding vector and transmitting the precoded signal through the active antenna ports.