Multi-Antenna Precoding via Coordination Server
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Solution Overview
Problem
In multi-antenna systems, independent clock sources among base stations lead to Carrier Frequency Offset (CFO), sampling clock offset, and timing offsets, causing inaccurate channel estimation and inter-cell and inter-user interference, which degrade system capacity.
Innovation Solution
A precoding method and system that involves a coordination server calculating channel calibration coefficients and using prediction functions to synchronize base stations, utilizing reference devices to transmit reference signals and estimate CFO, and generating precoders for improved channel estimation and interference reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple base stations are coordinated to transmit data (MCC system), then system capacity and spectrum usage efficiency are improved, but carrier frequency offset and channel estimation accuracy deteriorate due to independent clock sources
Solution Approach 1:
A coordination server is introduced as an intermediary to manage multiple base stations. The coordination server collects channel information from all base stations, calculates calibration coefficients to compensate for frequency offsets, and generates coordinated precoding matrices. This mediator enables accurate channel estimation and interference cancellation across the MCC system despite independent clock sources at each base station.
2Productivity
If the number of base station antennas is increased (massive antenna system), then spectrum usage efficiency is improved, but hardware complexity and synchronization difficulty worsen
Solution Approach 1:
The massive antenna system is segmented into multiple base stations, each with a manageable number of antennas. The coordination server divides the overall channel estimation and precoding tasks among these base stations. Each base station independently estimates its own channel and sends information to the coordination server, which then synthesizes the results. This segmentation reduces the hardware complexity at each individual base station while maintaining the benefits of massive MIMO through coordinated operation.
Data Source
AI summary
A precoding method in a multi-antenna system includes the following steps. A reference device transmits a first reference signal to base station antennas. A base station calculates uplink channel information and transmits it to a coordination server. The base station transmits a second reference signal to the reference device. The reference device calculates downlink channel information and transmits it to the coordination server. The coordination server performs the following steps: calculate carrier frequency offsets (CFO) between base stations according to the uplink channel information; calculate channel calibration coefficients according to the CFO, the uplink channel information, and the downlink channel information; calculate a first downlink channel at a first time point according to a user equipment's first uplink channel and the channel calibration coefficients; use a prediction function to predict a second downlink channel at a second time point; generate a precoder according to the second downlink channel.