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Interference Mitigation using Optimized Angle Diversity Receiver in LiFi Cellular Network

Zhihong Zeng, Chen Chen, Svetislav Savovi, Mohammad Dehghani Soltani, Cheng Chen, Majid Safari, Harald Haas

TL;DR

This work addresses inter-cell interference in LiFi attocell networks by designing and optimizing angle diversity receivers (ADRs), specifically comparing pyramid receivers (PRs) and truncated pyramid receivers (TPRs). It derives ADR coverage and a lower bound on the per-PD FOV under realistic conditions including random UE orientation and diffuse reflections, and introduces a double-source (DS) cell configuration to further mitigate interference. The study analyzes signal combining schemes—select-best combining (SBC) and maximum ratio combining (MRC)—across noise regimes and demonstrates DS can offer significant SINR gains in interference-dominated settings, while MRC outperforms SBC in noise-limited scenarios. By integrating LOS/NLOS channel modeling, device orientation effects, bandwidth considerations, and geometry-based FOV optimization, the paper provides actionable design guidelines for ADRs in practical LiFi deployments.

Abstract

Light-fidelity (LiFi) is an emerging technology for high-speed short-range mobile communications. Inter-cell interference (ICI) is an important issue that limits the system performance in an optical attocell network. Angle diversity receivers (ADRs) have been proposed to mitigate ICI. In this paper, the structure of pyramid receivers (PRs) and truncated pyramid receivers (TPRs) are studied. The coverage problems of PRs and TPRs are defined and investigated, and the lower bound of field of view (FOV) for each PD is given analytically. The impact of random device orientation and diffuse link signal propagation are taken into consideration. The performances of PRs and TPRs are compared and then optimized ADR structures are proposed. The performance comparison between the select best combining (SBC) and maximum ratio combining (MRC) is given under different noise levels. It is shown that SBC will outperform MRC in an interference limited system, otherwise, MRC is a preferred scheme. In addition, the double source system, where each LiFi AP consists of two sources transmitting the same information signals but with opposite polarity, is proved to outperform the single source (SS) system under certain conditions.

Interference Mitigation using Optimized Angle Diversity Receiver in LiFi Cellular Network

TL;DR

This work addresses inter-cell interference in LiFi attocell networks by designing and optimizing angle diversity receivers (ADRs), specifically comparing pyramid receivers (PRs) and truncated pyramid receivers (TPRs). It derives ADR coverage and a lower bound on the per-PD FOV under realistic conditions including random UE orientation and diffuse reflections, and introduces a double-source (DS) cell configuration to further mitigate interference. The study analyzes signal combining schemes—select-best combining (SBC) and maximum ratio combining (MRC)—across noise regimes and demonstrates DS can offer significant SINR gains in interference-dominated settings, while MRC outperforms SBC in noise-limited scenarios. By integrating LOS/NLOS channel modeling, device orientation effects, bandwidth considerations, and geometry-based FOV optimization, the paper provides actionable design guidelines for ADRs in practical LiFi deployments.

Abstract

Light-fidelity (LiFi) is an emerging technology for high-speed short-range mobile communications. Inter-cell interference (ICI) is an important issue that limits the system performance in an optical attocell network. Angle diversity receivers (ADRs) have been proposed to mitigate ICI. In this paper, the structure of pyramid receivers (PRs) and truncated pyramid receivers (TPRs) are studied. The coverage problems of PRs and TPRs are defined and investigated, and the lower bound of field of view (FOV) for each PD is given analytically. The impact of random device orientation and diffuse link signal propagation are taken into consideration. The performances of PRs and TPRs are compared and then optimized ADR structures are proposed. The performance comparison between the select best combining (SBC) and maximum ratio combining (MRC) is given under different noise levels. It is shown that SBC will outperform MRC in an interference limited system, otherwise, MRC is a preferred scheme. In addition, the double source system, where each LiFi AP consists of two sources transmitting the same information signals but with opposite polarity, is proved to outperform the single source (SS) system under certain conditions.

Paper Structure

This paper contains 32 sections, 58 equations, 16 figures, 1 table.

Table of Contents

  1. Introduction
  2. User Device Orientation
  3. Diffuse Link Signal Propagation
  4. Noise Power Spectral Density
  5. System Model
  6. Light Propagation Model
  7. LOS link
  8. NLOS link
  9. Signal Combining Schemes for ADR
  10. ADR Structure
  11. TPR Design
  12. PR Design
  13. Random Orientation Model
  14. Normal Vector of the ADR
  15. Receiver Bandwidth vs PD Area
  16. ...and 17 more sections

Figures (16)

  • Figure 1: ADR structures.
  • Figure 2: Representation of random UE orientation.
  • Figure 3: Visible area of PDs
  • Figure 4: Coverage area of PRs and TPRs with different number of PDs.
  • Figure 5: Visible area of ADR in $xz$-plane.
  • ...and 11 more figures