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Distributed Precoding for Satellite-Terrestrial Integrated Networks Without Sharing CSIT: A Rate-Splitting Approach

Doseon Kim, Sungyoon Cho, Wonjae Shin, Jeonghun Park, Dong Ku Kim

TL;DR

A novel distributed precoding method that disentangles the total spectral efficiency function into two distinct terms, each of which is dependent solely on the satellite’s precoder and the terrestrial BS’s precoder, respectively and offers considerable spectral efficiency gains compared to the existing methods.

Abstract

Satellite-terrestrial integrated networks (STINs) are promising architecture for providing global coverage. In STINs, full frequency reuse between a satellite and a terrestrial base station (BS) is encouraged for aggressive spectrum reuse, which induces non-negligible amount of interference. To address the interference management problem in STINs, this paper proposes a novel distributed precoding method. Key features of our method are: i) a rate-splitting (RS) strategy is incorporated for efficient interference management and ii) the precoders are designed in a distributed way without sharing channel state information between a satellite and a terrestrial BS. Specifically, to design the precoders in a distributed fashion, we put forth a spectral efficiency decoupling technique, that disentangles the total spectral efficiency function into two distinct terms, each of which is dependent solely on the satellite's precoder and the terrestrial BS's precoder, respectively. Then, to resolve the non-smoothness raised by the RS strategy, we approximate the spectral efficiency expression as a smooth function by using the LogSumExp technique; thereafter we develop a generalized power iteration inspired optimization algorithm built based on the first-order optimality condition. Simulation results demonstrate that the proposed method offers considerable spectral efficiency gains compared to the existing methods.

Distributed Precoding for Satellite-Terrestrial Integrated Networks Without Sharing CSIT: A Rate-Splitting Approach

TL;DR

A novel distributed precoding method that disentangles the total spectral efficiency function into two distinct terms, each of which is dependent solely on the satellite’s precoder and the terrestrial BS’s precoder, respectively and offers considerable spectral efficiency gains compared to the existing methods.

Abstract

Satellite-terrestrial integrated networks (STINs) are promising architecture for providing global coverage. In STINs, full frequency reuse between a satellite and a terrestrial base station (BS) is encouraged for aggressive spectrum reuse, which induces non-negligible amount of interference. To address the interference management problem in STINs, this paper proposes a novel distributed precoding method. Key features of our method are: i) a rate-splitting (RS) strategy is incorporated for efficient interference management and ii) the precoders are designed in a distributed way without sharing channel state information between a satellite and a terrestrial BS. Specifically, to design the precoders in a distributed fashion, we put forth a spectral efficiency decoupling technique, that disentangles the total spectral efficiency function into two distinct terms, each of which is dependent solely on the satellite's precoder and the terrestrial BS's precoder, respectively. Then, to resolve the non-smoothness raised by the RS strategy, we approximate the spectral efficiency expression as a smooth function by using the LogSumExp technique; thereafter we develop a generalized power iteration inspired optimization algorithm built based on the first-order optimality condition. Simulation results demonstrate that the proposed method offers considerable spectral efficiency gains compared to the existing methods.
Paper Structure (22 sections, 1 theorem, 47 equations, 5 figures, 2 tables, 1 algorithm)

This paper contains 22 sections, 1 theorem, 47 equations, 5 figures, 2 tables, 1 algorithm.

Table of Contents

  1. Introduction
  2. Related Work
  3. Contributions
  4. System Models
  5. Network Model
  6. Channel Model
  7. Satellite Channel
  8. Terrestrial Channel
  9. CSIT Estimation
  10. Signal Model
  11. Performance Metrics and Problem Formulation
  12. Spectral Efficiency Characterization
  13. Problem Formulation
  14. Reformulation to Distributed Problem
  15. Representation to a Tractable Form
  16. ...and 7 more sections

Key Result

Lemma 1

First, the first-order KKT condition of $f_1 (\bar{\bf{f}})$ is satisfied if where $\lambda^{\text{sat}}\left(\bar{\mathbf{f}}\right)$ is given by and $\mathbf{A}\left(\bar{\mathbf{f}}\right)$ and $\mathbf{B}\left(\bar{\mathbf{f}}\right)$ are shown at the top of the next page. Next, the first-order KKT condition of $f_2(\bar{\bf{v}})$ is satisfied if where $\lambda^{\text{bs}}\left(\bar{\mathb

Figures (5)

  • Figure 1: The system model of the STIN and the geometrical model of UPA.
  • Figure 2: The decoupling process from coordinated form to distributed form.
  • Figure 3: Comparison of sum spectral efficiency between the proposed distributed STIN-GPI and baseline methods.
  • Figure 4: The residual convergence comparison as the iterations, $\text{SNR}=0,15,30\text{dB}$. (a) set the initial value $\mu=0.1$ (b) set by increasing the initial value $\mu=0.5,0.8,1$ at $\text{SNR}=0,15,30\text{dB}$, respectively.
  • Figure 5: Comparison of sum spectral efficiency among different strategies under the assumption of $\text{SNR}=15\text{dB}$ (a) per the number of TUs experiencing interference from the satellite $(K_t^{{\text{int}}})$, (b) per the CSIT accuracy $(\tau p^{\textnormal{pi}})$.

Theorems & Definitions (7)

  • Remark 1
  • Remark 2
  • Remark 3
  • Remark 4
  • Remark 5
  • Lemma 1
  • proof : Proof