
This simulation code package is mainly used to reproduce the results of the following paper [1]:

[1] M. Cui and L. Dai, “Near-field wideband beamforming for extremely large antenna arrays,” IEEE Trans. Wireless Commun., vol. 23, no. 10, pp. 13110-13124, Oct. 2024.
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If you use this simulation code package in any way, please cite the original paper [1] above. 
 
The author in charge of this simulation code pacakge is: Mingyao Cui (email: cui-my16@tsinghua.org.cn).

Reference: We highly respect reproducible research, so we try to provide the simulation codes for our published papers 
( more information can be found at: 
http://oa.ee.tsinghua.edu.cn/dailinglong/publications/publications.html )

Please note that the MATLAB R2024a is used for this simulation code package,  
and there may be some imcompatibility problems among different MATLAB versions. 

Copyright reserved by the Broadband Communications and Signal Processing Laboratory (led by Dr. Linglong Dai), 
Department of Electronic Engineering, Tsinghua University, Beijing 100084, China. 

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Abstract of the paper: 
The natural integration of extremely large antenna arrays (ELAAs) and terahertz (THz) communications can 
potentially establish Tbps data links for 6G networks. However, due to the extremely large array aperture and wide bandwidth, a new
phenomenon termed as “near-field beam split” emerges. This phenomenon causes beams at different frequencies to focus on
distinct physical locations, leading to a significant loss of the beamforming gain. To address this challenging problem, we first
harness a piecewise-far-field channel model to approximate the complicated near-field wideband channel. In this model, the
entire large array is partitioned into several small sub-arrays. While the wireless channel’s phase discrepancy across the entire
array is modeled as near-field spherical, the phase discrepancy within each sub-array is approximated as far-field planar. Built
on this approximation, a phase-delay focusing (PDF) method employing delay phase precoding (DPP) architecture is proposed.
Our PDF method could compensate for the intra-array farfield phase discrepancy and the inter-array near-field phase
discrepancy via the joint control of phase shifters and time delayers, respectively. Theoretical and numerical results are
provided to demonstrate the efficiency of the proposed PDF method in mitigating the near-field beam split effect. Finally,
we define and derive a novel metric termed as the “effective Rayleigh distance” by the evaluation of beamforming gain loss.
Compared to classical Rayleigh distance, the effective Rayleigh distance is more accurate in determining the near-field range for
practical communications.
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How to use this simulation code package?

1. Fig. 10 in this paper can be obtained by running "sum_rate_vs_dis.m".
2. Fig. 11 in this paper can be obtained by running "sum_rate_vs_Nt.m".
3. Fig. 12 in this paper can be obtained by running "sum_rate_vs_SNR.m".
4. Fig. 13 in this paper can be obtained by running "energy_efficentcy_vs_Nu.m".
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Enjoy the reproducible research!