Evaluation of Interference Cancellation Architectures for Heterogeneous Cellular Networks

Table of Contents

1 Introduction

1.1 Motivation and Objective

1.2 Outline and Organization of the Thesis

2 Fundamentals

2.1 Bit-Interleaved Coded Modulation

2.1.1 System and Signal Model

2.1.2 Low Complexity LLR Metrics for BICM Receivers

2.2 Interference-Aware System

2.2.1 IA Receiver: System & Signal Model

3 Structure of the Simulator

3.1 System Parameters & General Code Structure

3.2 Radio Propagation Channel

3.2.1 Simulation of AWGN-Channel model

3.2.2 Path Loss Channel Model

3.2.3 Simulation of Rayleigh Fading Channel

3.3 The Baseband Part of the Transmitter

3.3.1 Convolutional Coding and Puncturing

3.3.2 Bit-Interleaver

3.3.3 Bit-Level Scrambling

3.4 Interference Model

3.5 The Baseband Part of the Receiver

3.5.1 Pilot-based Channel Estimation

3.5.2 De-Puncturing and Soft Output Viterbi Decoding

3.5.3 Metric Computing Device

3.6 Base Stations Channel Estimation Enhancement

3.6.1 Serving Base Station: Holes

3.6.2 Interfering BS: Pilot Boosting

4 Simulation Results

5 Summary and Outlook

Objectives and Thematic Focus

The primary objective of this thesis is to evaluate downlink interference cancellation architectures for heterogeneous cellular networks, focusing on the development of an interference-aware receiver (IA-R) that utilizes base station coordination for improved channel estimation.

• Bit-interleaved coded modulation (BICM) performance in interference-limited scenarios.
• Evaluation of interference-aware (IA-R) versus interference-ignorant (II-R) receiver architectures.
• Impact of channel estimation quality on receiver performance in heterogeneous environments.
• Proposed solutions for performance enhancement via serving base station holes and pilot boosting.
• Validation of the proposed architectures through Monte Carlo simulations in a Matlab-based environment.

Excerpt from the Book

Summary of Chapters

1 Introduction: Provides the motivation for the thesis, outlining the shift towards heterogeneous cellular networks and the need for intelligent interference cancellation at the user equipment.

2 Fundamentals: Introduces core concepts including Bit-Interleaved Coded Modulation (BICM) and the mathematical framework for interference-aware receivers.

3 Structure of the Simulator: Details the Matlab-based transceiver model, including propagation channel modeling, the interference environment, and proposed enhancements for channel estimation.

4 Simulation Results: Presents the performance analysis of the proposed IA-R architectures compared to II-R, demonstrating the necessity of base station support for effective interference cancellation.

5 Summary and Outlook: Consolidates the research findings and suggests future directions such as the integration of MIMO and turbo coding.

Keywords

Heterogeneous networks, Interference cancellation, Bit-interleaved coded modulation, LLR metrics, LTE, AWGN, Rayleigh fading, Channel estimation, Pilot boosting, Base station coordination, BER performance, Signal-to-Interference Ratio, Simulation testbed, Interference-aware receiver, Downlink transmission

Frequently Asked Questions

What is the core focus of this thesis?

The thesis focuses on improving downlink performance in heterogeneous cellular networks by implementing and evaluating interference-aware receivers that effectively manage co-channel interference.

What are the central thematic fields?

The research covers cellular network architectures, digital signal processing in receivers, channel modeling (AWGN and Rayleigh fading), and interference management techniques.

What is the primary research goal?

The goal is to determine how an intelligent receiver can best cancel inter-cell interference, specifically through collaborative channel estimation processes between base stations and the user equipment.

Which scientific method is applied?

The author utilizes a system-level simulation approach, implementing a baseband transceiver model in Matlab to conduct Monte Carlo simulations and evaluate Bit Error Rate (BER) performance.

What is covered in the main section of the work?

The main section details the construction of an LTE-compliant simulation testbed, including transmitter and receiver baseband components, interference models, and two specific optimization techniques for channel estimation: pilot holes and pilot boosting.

Which keywords characterize this work?

Key terms include heterogeneous cellular networks, interference cancellation, BICM, channel estimation, pilot boosting, and performance evaluation under various signal-to-interference ratios.

How does the "Pilot Boosting" method benefit the receiver?

Pilot boosting allows the interfering base station to adjust its power allocation, thereby reducing interference for the desired signal while maintaining overall power consistency, which improves the receiver's channel estimation quality.

Why is "Serving Base Station Holes" proposed?

This technique creates "holes" at the positions of interfering pilots to isolate the channel estimation of the interferer, reducing it to a noise-limited problem rather than an interference-limited one.

What conclusion does the author reach regarding the IA-R?

The author concludes that while the interference-aware receiver is a promising concept, it requires active support from base stations in the form of coordination or specific enhancements to function effectively in real-world scenarios.