A New Trade-off Scheme for MIMO OFDM-based Cognitive Radio ... · PDF fileA New Trade-off...

A New Trade-off Scheme for MIMO

OFDM-based Cognitive Radio

Systems over Correlated Fading Channels

1

1: Makan Zamanipour

IEEE Member Tehran, Iran

2: Saeed Mashhadi

Sharif University of Technology Tehran, Iran

17th FRUCT: 20-24 April, 2015, Yaroslavl

Preface

Introduction Assumptions

Correlated MIMO Channels

Challenges/Motivations

Trade-off Scheme Network Model

Problem Formulation System Model

OSTFB Coding in MIMO OFDM Scheme

Optimization Problem

Robust Beamforming

Results

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Introduction Assumptions

Channels: Quasi Static Rayleigh

Frequency Selective Fading

Domain: Frequency

Cognitive Radio: Underlay Scenario

Transmit-receive Scenario: Down-link Multi-user Scenario

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Antenna Distance Carrier Frequency ...... 2

d

Transmit-Angle Spread

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Introduction Correlated MIMO Channels

Introduction Challenge/Motivation

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Kronecker Model:

Introduction Challenge/Motivation

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Introduction Challenge/Motivation

Solution: Pre-coding/Post-coding

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Introduction Challenge/Motivation

Solution: Pre-coding/Post-coding

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Yes No

Effect

on

SNR

Effect

on

SNR

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Trade-off Scheme Network Model

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Trade-off Scheme Network Model

Small Eigen-values

OSTFBCs

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Trade-off Scheme Network Model

Small Eigen-values

OSTFBCs

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Trade-off Scheme Network Model

Secrecy: Probability of Eavesdropping

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Problem Formulation System Model

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Problem Formulation OSTFB Coding

Frequency Selective Fading Channels

Problem Formulation Optimization Problem

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Problem Formulation Optimization Problem

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Problem Formulation Optimization Problem

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Problem Formulation Optimization Problem

Decrease in Search Region

Small Eigen-values: As much as Possible

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Lagrange Method:

A Closed-form Solution (THEOREM 4)

Problem Formulation Optimization Problem

Problem Formulation Robust Beamforming

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Estimation of Correlation Matrices: Error

Solve the Problem in Worst Case

Problem Formulation Robust Beamforming

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Results

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Complexity Should be Examined!

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