Inter-Cell Antenna Calibration for Coherent Joint Transmission in TDD System

TL;DR

This paper presents a calibration method for reciprocity errors in TDD CoMP joint transmission systems, using UE feedback to improve phase alignment between cells, with simulation results demonstrating its effectiveness.

Contribution

It introduces a novel inter-cell antenna calibration technique based on PMI feedback, addressing reciprocity errors in TDD CoMP systems.

Findings

The calibration method accurately estimates residual phase differences.

Performance remains robust across different SNR and CRS configurations.

The method improves coherent joint transmission quality.

Abstract

In this work the modeling and calibration method of reciprocity error in a coherent TDD coordinated multi-point (CoMP) joint transmission (JT) system are addressed. The modeling includes parameters such as amplitude gains and phase differences of RF chains between the eNBs. The calibration method used for inter-cell antenna calibration is based on precoding matrix indicator (PMI) feedback by UE. Furthermore, we provide some simulation results for evaluating the performance of the calibration method in different cases such as varying estimation-period, cell-specific reference signals (CRS) ports configuration, signal to noise ratio (SNR), phase difference, etc. The main conclusion is that the proposed method for intercell antenna calibration has good performance for estimating the residual phase difference. Keywords-LTE-Advanced; TDD; CoMP; JT; reciprocity error; phase difference; inter-cell antenna calibration