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HANDBOOK ON GREEN INFORMATION AND COMMUNICATION SYSTEMS

Chapter 15 Energy Efficient MIMO-OFDM Systems. HANDBOOK ON GREEN INFORMATION AND COMMUNICATION SYSTEMS. Zimran Rafique and Boon-Chong Seet Auckland University of Technology New Zealand. Table of Contents. INTRODUCTION.

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HANDBOOK ON GREEN INFORMATION AND COMMUNICATION SYSTEMS

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  1. Chapter 15 Energy Efficient MIMO-OFDM Systems HANDBOOK ON GREEN INFORMATION AND COMMUNICATION SYSTEMS Zimran Rafique and Boon-Chong Seet Auckland University of Technology New Zealand

  2. Table of Contents

  3. INTRODUCTION • Due to multimedia applications, wireless systems with higher data rate are required • Higher data rates necessitate more energy per bit for a given bit error rate (BER) • Thus, overall system energy consumption will increase • Corresponding increase in CO2 emission: threatens climate change and contributes to global warming • Energy efficient designs for high data-rate wireless systems is a crucial issue to be addressed

  4. INTRODUCTION Multi-Input-Multi-Output (MIMO) systems • In late 1990s, MIMO techniques were proposed to achieve higher data rates and smaller BER with the same transmit power and bandwidth required by single antenna system Orthogonal Frequency Division Multiplexing (OFDM) • OFDM is a multi carrier modulation technique which has the capability to mitigate the effect of inter-symbol-interference (ISI) at the receiver side

  5. INTRODUCTION Fourier based OFDM (FOFDM) Wavelet based OFDM (WOFDM) In WOFDM, wavelet bases are used to generate orthogonal carriers. These bases are generated using symmetric or asymmetric QMF structure of delay or delay-free type • In conventional OFDM, complex exponential Fourier bases are used to generate orthogonal subcarriers consist of a series of orthogonal sine/cosine functions

  6. INTRODUCTION MIMO-OFDM • MIMO techniques are used with OFDM (MIMO-OFDM) to enhance the system performance • MIMO-OFDM systems are capable of increasing the channel capacity even under severe channel conditions • Provide two dimensional space-frequency coding (SFC) in space and frequency using individual subcarriers of an OFDM symbol or three dimensional coding called space-time-frequency coding (STFC) to achieve larger diversity and coding gains • OFDM can also be used in multi-user cooperative communication system by assigning subcarrier to different users for overall transmit power reduction

  7. Multiple Antenna System • More than one antennas are used on transmitting • and/or receiving side • By using spatial multiplexing, data rate can be • increased • By using spatial diversity, BER can be improved • SNR can be improved at the receiver and • co-channel interference (CCI) can be eliminated • along with beam forming techniques MIMO wireless communication system

  8. The number of users, or data rate of a single user, can be increased by the factor of number • of transmitting antennas (Nt) for the same transmission power and bandwidth Multiple Antenna System • Individual transmitter antenna power is scaled by 1/ Nt, thus the total power remains • constant and independent of number of Nt • At the receiver, the transmitted signals are retrieved from received sequences (layers) • by using detection algorithms Spatial Multiplexing Techniques Spatial multiplexing system architecture with Nt transmitting and Nr receiving antennas

  9. Multiple Antenna System Spatial Multiplexing Techniques , D-BLAST

  10. Multiple Antenna System Spatial Multiplexing Techniques D-BLAST

  11. Multiple Antenna System Spatial Multiplexing Techniques D-BLAST

  12. Multiple Antenna System Spatial Multiplexing Techniques V-BLAST

  13. Multiple Antenna System Spatial Multiplexing Techniques V-BLAST

  14. Multiple Antenna System Spatial Multiplexing Techniques V-BLAST

  15. Multiple Antenna System Spatial Multiplexing Techniques V-BLAST

  16. Multiple Antenna System Spatial Multiplexing Techniques V-BLAST

  17. Multiple Antenna System Spatial Multiplexing Techniques Turbo-BLAST

  18. Multiple Antenna System Spatial Multiplexing Techniques Turbo-BLAST

  19. Multiple Antenna System Spatial Multiplexing Techniques Turbo-BLAST

  20. Multiple Antenna System Space Time Coding Techniques • By using space and time (two-dimensional coding), multiple antenna setups can be used to attain coding gain and diversity gain for the same bit rate, transmission power and bandwidth as compared single antenna system • Information bits are transmitted according to some pre-defined transmission sequence • At the receiver, the received signals are combined by using optimal combining scheme followed by a decision rule for maximum likelihood detection Space-time coding system architecture with Nt transmitting and Nr receiving antennas

  21. Multiple Antenna System Space Time Coding Techniques Alamouti STC Technique

  22. Multiple Antenna System Space Time Coding Techniques Alamouti STC Technique

  23. Multiple Antenna System Space Time Coding Techniques Space-Time Trellis Coding ( STTC) Technique

  24. Multiple Antenna System Space Time Coding Techniques Space-Time Trellis Coding ( STTC) Technique PSK 4-state space-time code with two transmitting antennas Time-delay diversity with 2 antennas

  25. Multiple Antenna System Space Time Coding Techniques Orthogonal Space-Time Block Coding ( OSTBC) Technique

  26. Multiple Antenna System Space Time Coding Techniques Orthogonal Space-Time Block Coding ( OSTBC) Technique

  27. Multiple Antenna System Space Time Coding Techniques Space-Time Vector Coding ( STVC) Technique

  28. Multiple Antenna System Space Time Coding Techniques Space-Time Vector Coding ( STVC) Technique

  29. Multiple Antenna System Beam-Forming • Multiple antennas capable of steering lobes and nulls of antenna beam • Co-channel interference cancellation can be done to improve SNR • and to reduce delay spread of the channel A beam-former with Nt transmitting and Nr receiving antennas

  30. Multiple Antenna System Beam-Forming Delay-Sum Beam-Former A Simple Delay-Sum Beam-Former

  31. Multiple Antenna System Beam-Forming V-BLAST MIMO System with Beam-Former V-BLAST MIMO system with beam-former

  32. Multiple Antenna System Multi-Functional MIMO Systems • Capable for achieving multiplexing gain, diversity gain and beamforming gain • Has Nt transmit antenna arrays (AAs) which are sufficiently apart to experience independent fading • LAA numbers of elements of each AA are spaced at a distance of λ/2 for achieving beamforming gain • Receiver is equipped with Nr receiving antennas Multi-functional MIMO system

  33. Multiple Antenna System Virtual MIMO (V-MIMO) Systems Models • Also known as cooperative MIMO systems • Proposed primarily for energy and physically constrained wireless nodes (e.g. sensor nodes) • to realize the advantages of MIMO techniques, which is otherwise not possible • V-MIMO systems are distributed in nature because multiple nodes are placed at different • physical locations to cooperate with each other • V-MIMO systems may also have problems such as time and frequency asynchronism Virtual-MIMO system models

  34. Multiple Antenna System Virtual MIMO Systems Models Virtual-MIMO system models

  35. Multiple Antenna System Virtual MIMO Systems Transmission-Delay for Model-d

  36. Multiple Antenna System Energy Efficiency of MIMO Systems

  37. Multiple Antenna System Energy Efficiency of MIMO Systems

  38. Multiple Antenna System Energy Efficiency of MIMO Systems

  39. Multiple Antenna System Energy Efficiency of MIMO Systems Transmitter and receiver architecture (In-Phase/Quadrature-Phase) for FOFDM and QAM (analog)

  40. Multiple Antenna System Energy Efficiency of MIMO Systems

  41. Multiple Antenna System Energy Efficiency of MIMO Systems

  42. Multiple Antenna System Energy Efficiency of MIMO Systems

  43. OFDM & WOFDM OFDM

  44. OFDM & WOFDM Orthogonality Principle of OFDM Comparison of the bandwidth utilization for FDM and OFDM

  45. OFDM & WOFDM Fourier based OFDM (FOFDM)

  46. OFDM & WOFDM Fourier based OFDM (FOFDM) A basic FOFDM based communication system

  47. OFDM & WOFDM Fourier based OFDM (FOFDM) FOFDM modulator and demodulator with filter bank structure

  48. OFDM & WOFDM Wavelet based OFDM (WOFDM) Constellation Diagram of WOFDM

  49. OFDM & WOFDM Wavelet based OFDM (WOFDM)

  50. OFDM & WOFDM Wavelet based OFDM (WOFDM)

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