Reference Signal Power Distribution in MIMO Systems
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Solution Overview
Problem
Current wireless communication systems face challenges in accurately demodulating signals due to inefficient allocation of transmission power for Reference Signals (RSs), leading to suboptimal channel estimation and data transmission efficiency, especially in Multiple Input Multiple Output (MIMO) systems with limited total transmission power.
Innovation Solution
The method involves allocating orthogonal sequences with predetermined offsets across subcarriers in Code Division Multiplexing (CDM) groups and applying phase offsets to RSs, allowing for efficient power distribution across Orthogonal Frequency Division Multiplexing (OFDM) symbols, thereby enhancing the accuracy of RS transmission and reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If transmission power is concentrated on specific OFDM symbols for Reference Signal transmission, then RS transmission quality is improved, but power distribution efficiency deteriorates and overall system throughput is limited
Solution Approach 1:
The patent changes the power distribution parameter from concentrated allocation to uniform allocation across OFDM symbols. By setting the RS transmission power equal to the data transmission power on each subcarrier (P_rs = P_data), the system achieves both adequate channel estimation accuracy and maximized overall throughput, resolving the contradiction between measurement precision and productivity.
2Measurement precision
If total transmission power is increased to improve channel estimation accuracy, then RS reception quality is improved, but system power efficiency deteriorates
Solution Approach 1:
The patent optimizes the power parameter by establishing a specific relationship between RS power and data power (P_rs = P_data). This parameter setting ensures that RS transmission receives adequate power for accurate channel estimation while maintaining overall power efficiency, as the power is drawn from the existing data transmission budget rather than requiring additional total power.
3Measurement precision
If more Reference Signals are transmitted to improve channel estimation, then data demodulation accuracy is improved, but transmission overhead increases
Solution Approach 1:
The patent optimizes the quantity parameter by determining the minimal sufficient number of RS instances needed for accurate channel estimation. By using uniform power distribution across OFDM symbols, the system achieves adequate channel estimation with fewer RS transmissions compared to concentrated power allocation, thereby reducing transmission overhead while maintaining demodulation accuracy.
Data Source
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AI summary
A method and apparatus for multiplexing reference signals in a predetermined number of Code Division Multiplexing (CDM) groups to balance power across Orthogonal Frequency Division Multiplexing (OFDM) symbols are disclosed. In a wireless communication system, orthogonal sequences used for spreading the reference signals are allocated such that the order of orthogonal sequences allocated to a subcarrier of one CDM group has a predetermined offset with respect to the order of orthogonal sequences allocated to a subcarrier of another CDM group, adjacent to the subcarrier of the one CDM group.