MIMO-OFDM Wireless Communications with MATLAB

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MIMO-OFDM WirelessCommunicationswith MATLAB
Chapter 4. Introduction to OFDM

• Yong Soo Cho Jaekwon Kim
• Won Young Yang Chung G. Kang

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Chapter 4. Introduction to OFDM

• 4.1 SINGLE-CARRIER VS. MULTI-CARRIER
  TRANSMISSION
• - 4.1.1 Single-Carrier Transmission
• - 4.1.2 Multi-Carrier Transmission
• - 4.1.3 Single-Carrier vs. Multi-Carrier
  Transmission
• 4.2 BASIC PRINCIPLE OF OFDM
• - 4.2.1 OFDM Modulation and Demodulation
• - 4.2.2 OFDM Guard Interval
• - 4.2.3 OFDM Guard Band
• - 4.2.4 BER of OFDM Scheme
• - 4.2.5 Water-Filling Algorithm for
  Frequency-domain Link Adaptation

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Chapter 4. Introduction to OFDM

• 4.3 CODED OFDM
• - 4.4 OFDMA MULTIPLE ACCESS EXTENSIONS OF
  OFDM
• - 4.4.1 Resource Allocation - Subchannel
  Allocation Types
• - 4.4.2 Resource Allocation
  Subchannelization
• 4.5 DUPLEXING

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Chapter 4. Introduction to OFDM4.1
Single-Carrier vs. Multi-Carrier
Transmission4.1.1.1 Single-Carrier Baseband
Transmission System Model
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4.1.1.1 Single-Carrier Baseband Transmission
System Model
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4.1.1.2 ISI and Nyquist Criterion
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4.1.1.2 ISI and Nyquist Criterion
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4.1.1.2 ISI and Nyquist Criterion
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4.1.2 Multi-Carrier Transmission4.1.2.1 Basic
Structure of a Multi-Carrier
Transmission Scheme
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4.1.2.1 Basic Structure of a Multi-Carrier
Transmission Scheme
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4.1.2.1 Basic Structure of a Multi-Carrier
Transmission Scheme
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4.1.2.2 OFDM Transmission Scheme
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4.1.2.2 OFDM Transmission Scheme
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4.1.2.3 FMT Transmission Scheme
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4.1.3 Single-Carrier vs. Multi-Carrier
Transmission
Single-carrier Transmission Multi-carrier Transmission Multi-carrier Transmission
Single-carrier Transmission OFDM/DMT FMT
Subcarrier spacing - 1/(symbol duration) 1/(symbol duration)
Pulse shaping Nyquist filter (e.g., raised-cosine filter) Window (e.g. rectangular) Nyquist filter (e.g., raised-cosine filter)
Subchannel separation - Orthogonality Bandpass filter
Guard Interval Not required Required (CP) Not required
Guard Band Not required Required (VC) Not required
Advantages Simple in flat fading channels High bandwidth efficiency for a large number of subcarriers ( 64) Small ACI
Disadvantages High-complexity equalizer required for frequency-selective channels Low bandwidth efficiency and large ACI for a small number of subcarriers High bandwidth efficiency for a small number of subcarriers (lt64)
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4.2 Basic Principle of OFDM4.2.1 OFDM Modulation
and Demodulation4.2.1.1 Orthogonality
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4.2.1.1 Orthogonality
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4.2.1.1 Orthogonality
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4.2.1.1 Orthogonality
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4.2.1.1 Orthogonality
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4.2.1.2 OFDM Modulation and Demodulation
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4.2.1.2 OFDM Modulation and Demodulation
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4.2.1.2 OFDM Modulation and Demodulation
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4.2.1.2 OFDM Modulation and Demodulation
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4.2.2 OFDM Guard Interval4.2.2.1 Effect of
Multipath Channel on OFDM Symbols
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4.2.2.1 Effect of Multipath Channel on OFDM
Symbols
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4.2.2.1 Effect of Multipath Channel on OFDM
Symbols
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4.2.2.2 Cyclic Prefix (CP)
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4.2.2.2 Cyclic Prefix (CP)
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4.2.2.2 Cyclic Prefix (CP)
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4.2.2.2 Cyclic Prefix (CP)
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4.2.2.2 Cyclic Prefix (CP)
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4.2.2.2 Cyclic Prefix (CP)
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4.2.2.2 Cyclic Prefix (CP)
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4.2.2.3 Cyclic Suffix (CS)
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4.2.3 OFDM Guard Band
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4.2.3 OFDM Guard Band
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4.2.3 OFDM Guard Band
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4.2.3 OFDM Guard Band
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4.2.3 OFDM Guard Band
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4.2.3 OFDM Guard Band
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4.2.3 OFDM Guard Band
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4.2.4 BER of OFDM Scheme
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4.2.4 BER of OFDM Scheme
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4.2.5 Water-Filling Algorithm for Frequency-
Domain Link Adaptation
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4.2.5 Water-Filling Algorithm for Frequency-
Domain Link Adaptation
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4.2.5 Water-Filling Algorithm for Frequency-
Domain Link Adaptation
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4.2.5 Water-Filling Algorithm for Frequency-
Domain Link Adaptation
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4.3 Coded OFDM
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4.3 Coded OFDM
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4.4 OFDMA Multiple Access Extensions of
OFDM
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4.4 OFDMA Multiple Access Extensions of
OFDM
Attributes Attributes TDMA FDMA CDMA
Method Method one user/subset of time slots/ all subcarriers multiple users/same time/ subset of subcarriers all users/same time/ all subcarriers
Flexibility Flexibility variable number of time slots variable number of subcarriers variable number of spreading code
MAI Intra-cell none None Present
MAI Inter-cell present Present Present
MAI suppression MAI suppression interference avoidance (low frequency reuse factor) interference avoidance interference averaging multi-user detection interference averaging
Others Others small FFT size isolated cell (wireless LAN) large FFT size cellular system multi-user diversity power concentration inherent frequency diversity
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4.4.1 Resource Allocation-Subchannel
Allocation Types
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4.4.1 Resource Allocation-Subchannel
Allocation Types
Type Block (Cluster) Comb (Interleaved) Random
Method Adjacent subcarriers Equidistant subcarriers Random subcarriers
Diversity Frequency hopping required Frequency diversity gain Frequency diversity gain
Mobility Slow Fast Fast
Channel Estimation Simple (coherence BW) Whole band Whole band
Inter-cell Interference Coordination required Coordination required Interference averaging
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4.4.2 Resource Allocation -
Subchannelization
Subchannels Name Configuration Usage
Diversity subchannel Downlink PUSC Scattered 48 tones FCH/DL-MAP (Reuse 3), Data transmission
Diversity subchannel Downlink FUSC Scattered 48 tones Data transmission, Broadcasting
Diversity subchannel Downlink OFUSC Scattered 48 tones Data transmission, Broadcasting
Diversity subchannel Uplink PUSC 6 distributed tiles 8 tones/tile Data transmission, Broadcasting
Diversity subchannel Uplink OPUSC 6 distributed tiles 8 tones/tile Data transmission, Broadcasting
Band AMC downlink/uplink (band AMC) AMC 6 adjacent bins 8 tones/bin Data transmission, AMC, AAS
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4.4.2 Resource Allocation -
Subchannelization
Parameters PUSC FUSC OFUSC Band AMC
No. of Left Guard Subcarriers 92 87 80 80
No. of Right Guard Subcarriers 91 86 79 79
No. of Used Subcarriers (no DC) 840 850 864 864
No. of DC Subcarrier (512) 1 1 1 1
No. of Pilot Subcarriers 120 82 96 96
No. of Data Subcarriers 720 768 768 468
No. of Subcarriers per Subchannel 48 48 48 48
No. of Symbols per Subchannel 2 1 1 2, 3, 6
No. of Subchannels/symbol 30 16 16 48
Pilot Configuration Common Common Common Dedicated
Data Configuration Distributed Distributed Distributed Adjacent
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4.4.2 Resource Allocation -
Subchannelization
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4.4.2 Resource Allocation -
Subchannelization
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4.4.2 Resource Allocation -
Subchannelization
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4.4.2 Resource Allocation -
Subchannelization
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4.4.2 Resource Allocation -
Subchannelization
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4.5 Duplexing
FDD TDD
Spectrum 2 separate band for each link (guard band) single channel (guard time)
Duplexing full duplex half duplex
Flexibility (DL/UL) low high
Complexity/Cost high (RX filter, etc.) low
Coverage wide coverage small coverage
Mobility high low
Etc. low latency symmetric channel