i VIET NAM NATIONAL UNIVERSITY, HA NOI UNIVERSITY OF ENGINEERING AND TECHNOLOGY PERFORMANCE ANALYSIS OF NETWORK MIMO SYSTEMS A THESIS SUBMITTED IN FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MAST[.]
VIET NAM NATIONAL UNIVERSITY, HA NOI UNIVERSITY OF ENGINEERING AND TECHNOLOGY PERFORMANCE ANALYSIS OF NETWORK-MIMO SYSTEMS A THESIS SUBMITTED IN FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF EECTRICAL ENGINEERING DUC-TUYEN TA 2010 Supervisor: Dr Trinh Anh Vu i z ACKNOWLEDGMENTS First and foremost, I would like to express my gratitude to Dr Trinh Anh Vu for being a great mentor and for numerous technical discussions and suggestions that have found their way into this thesis I also very thank to all my colleagues at University of Engineering and Technology, VNU who have contributed greatly to provide a supportive and collaborative research atmosphere Many thanks to Phd Tran Duc Tan and Dinh Van Phong, with whom I have had opportunities to collaborate on various subjects I would like to sincerely thank my parents for their support, encouragement, and love throughout my life This thesis is dedicated to them ii z ABSTRACT Network MIMO is a means of coordinating and processing the information gathered from multiple- input multiple- output (MIMO) communication systems to increase spectral efficiency, robustness, and data rates These properties make it a topic of great interest in the near future as the number of wireless users continues to grow and their individual demands on bandwidth climb Systems employing network MIMO capitalize on the fact that inter-cell interference, a major problem for dense wireless systems, is a superposition of signals With careful coordination between receivers (and transmitters), these super-positions can be decoupled and the information they contain can be utilized The goal of this thesis is to investigate the ability of network MIMO techniques to increase data rates in multi-user indoor wireless networks of various sizes with various channel schemes The simulation results also show that Network MIMO systems can be increase data rates and good through put than non- networked MIMO systems iii z AUTHOR’S DECLARATION I declare that the work in this thesis was carried out in accordance with the Regulations of the University of Engineering and Technology, VNU The work is original except where indicated by special reference in the text and no part of the thesis has been submitted for any other degree Any views expressed in the dissertation are those of the author and not necessarily represent those of the University of Engineering, VNU The thesis has not been presented to any other university for examination either in Viet Nam or overseas Duc-Tuyen Ta 15 October 2010 iv z TABLE OF CONTENTS Page LIST OF TABLES vii LIST OF FIGURES viii ABBREVIATIONS xi CHAPTER 1: INTRODUCTION 1.1 Wireless Communication 1.2 MIMO Techniques 1.3 Network-MIMO systems 1.4 Thesis’s Structure CHAPTER 2: BASIC MIMO THEORY 2.1 Wireless Background 2.2 MIMO Communications 2.2.1 MIMO systems Model 2.2.2 Theoretical MIMO Capacity Gains 10 2.2.3 Types of MIMO 12 2.3 Multi-user Communications 12 2.3.1 Limitations of Single-User view 13 2.3.2 Multi-User MIMO (MU-MIMO) 14 2.4 Multi-cell Communications 18 2.4.1 Limitations of Single-Cell View 19 2.4.2 Multi-Cell MIMO 19 3.1 Background 21 3.1.1 Inter-cell Interference 21 3.2 Theory behind Network MIMO 27 3.3 Network-MIMO systems Model 28 v z 3.3.1 Uplink 29 3.3.2 Downlink 30 CHAPTER 4: SIMULATION AND RESULTS 34 4.1 Simulation Model 34 4.2 Simulation Diagram 36 4.3 Simulation Results 39 CHAPTER 5: CONCLUSION 45 REFERENCES 46 vi z LIST OF TABLES Page Table Power Delay Profile 35 Table Simulation parameters 39 vii z LIST OF FIGURES Page Figure MIMO communication from SISO to IA-MIMO (Source: www.wikipedia.org) Figure MIMO channel with M transmit and N receive antennas The sketched path, from transmitter and receiver, represent the channel which h11 is the channel between transmit antenna and receive antenna The transmit and receive signal are often presented by “black boxes” Figure From single- to multiuser communications, where all the users in the coverage area are simultaneously considered in the optimization The base station may choose to transmit data to a single or multiple user terminals at once 14 Figure Illustration of MU-MIMO: Downlink and Uplink 15 Figure MU-MIMO systems: MIMO Broadcast (Source: www.wikipedia.org) 16 Figure MU-MIMO systems: MIMO MAC (Source: www.wikipedia.org) 17 Figure Frequency reused in cellular network with the reuse factor is and Cells of same color are used with same frequency 18 Figure From multi-user to multi cell communication, where all the cells and all the users in the network are simultaneously considered in optimization The solid line marks the useful signals, where the interfering is dashed 20 Figure Coordination or Cooperation between all base stations in the wireless communication network under fast backhaul The central unit played an central network controller for control the coodination/cooperation between all the BS 20 Figure 10 Illustration of typical interference between users and access points in a cell-based wireless system The left image shows interference in down link and the right image shows interference in uplink 22 viii z Figure 11 Illustration of traditional interference control between users and access points in a cell-based wireless system The left image shows down link and the right image shows uplink 23 Figure 12 Illustration of MIMO interference control between users and access points in a cell-based wireless system The left image shows down link and the right image shows uplink 24 Figure 13 Example of a small wireless communication with terminals, AP and the Central Network Controller 25 Figure 14 Network MIMO solution where all the signals are useful, i.e., interference is removed 25 Figure 15 Conventional vs Network MIMO average SINR and data rate improvements 26 Figure 16 Wireless network with two transmit and two receive antennas communicating through independent channels 27 Figure 17 Network-MIMO uplink channel: from m-th cell to all of base station 29 Figure 18 Network-MIMO downlink channel: from all base station to k-th user in the m-th cell 31 Figure 19 Block Diagram showing key functions that are to be implemented in MATLAB simulation 37 Figure 20 Simulation environment with cell, each cell include access point and end-user with randomly place 40 Figure 21 OFDM Pilot symbol to estimate the channel state information at both transmitter (AP/user) and receiver (user/AP) side with users 41 Figure 22 Compare between real channel and the estimated channel by using pilot symbol 42 ix z Figure 23 Channel estimation between 4-th AP and 1-st User (in the different cell) and the channel between 1-st AP and 1-st cell (in the same cell) 43 Figure 24 Comparison between performance of Network-MIMO and non Network-MIMO communication system with the ranger of Signal-to-Noise Ratio (SNR) is 10 to 20 dB 43 x z ... thesis focuses on performance analysis of network MIMO systems Because Network- MIMO is an enhancement model of the original MIMO systems, we first analysis the theoretical of MIMO techniques in... fairness • etc 1.3 Network- MIMO systems Network MIMO is a MIMO communication scheme, which falls within the family of techniques that use cooperation in a MIMO systems to increase system performance. .. once 14 Figure Illustration of MU -MIMO: Downlink and Uplink 15 Figure MU -MIMO systems: MIMO Broadcast (Source: www.wikipedia.org) 16 Figure MU -MIMO systems: MIMO MAC (Source: www.wikipedia.org)