1. MIMO-OFDM Wireless Communications with MATLAB®
Chapter 4. Introduction to OFDM
Yong Soo Cho | Jaekwon Kim
Won Young Yang | Chung G. Kang 1

2. Chapter 4. Introduction to OFDM
4.1 SINGLE-CARRIER VS. MULTI-CARRIER TRANSMISSION
Single-Carrier Transmission
Multi-Carrier Transmission
Single-Carrier vs. Multi-Carrier Transmission
4.2 BASIC PRINCIPLE OF OFDM
OFDM Modulation and Demodulation
OFDM Guard Interval
OFDM Guard Band
BER of OFDM Scheme
Water-Filling Algorithm for Frequency-domain Link Adaptation

3. Chapter 4. Introduction to OFDM
4.3 CODED OFDM
OFDMA: MULTIPLE ACCESS EXTENSIONS OF OFDM
Resource Allocation - Subchannel Allocation Types
Resource Allocation – Subchannelization
4.5 DUPLEXING

4. Chapter 4. Introduction to OFDM 4. 1 Single-Carrier vs
Chapter 4. Introduction to OFDM 4.1 Single-Carrier vs. Multi-Carrier Transmission Single-Carrier Baseband Transmission : System Model

5. 4.1.1.1 Single-Carrier Baseband Transmission : System Model

6. 4.1.1.2 ISI and Nyquist Criterion

7. 4.1.1.2 ISI and Nyquist Criterion

8. 4.1.1.2 ISI and Nyquist Criterion

9. 4. 1. 2 Multi-Carrier Transmission 4. 1. 2
4.1.2 Multi-Carrier Transmission Basic Structure of a Multi-Carrier Transmission Scheme

10. 4.1.2.1 Basic Structure of a Multi-Carrier Transmission Scheme

11. 4.1.2.1 Basic Structure of a Multi-Carrier Transmission Scheme

12. 4.1.2.2 OFDM Transmission Scheme

13. 4.1.2.2 OFDM Transmission Scheme

14. 4.1.2.3 FMT Transmission Scheme

15. 4.1.3 Single-Carrier vs. Multi-Carrier Transmission
Single-carrier Transmission
Multi-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)
Subchannel separation
Orthogonality
Bandpass filter
Guard Interval
Not required
Required (CP)
Guard Band
Required (VC)
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
(＜64)

16. 4.2 Basic Principle of OFDM 4.2.1 OFDM Modulation and Demodulation 4.2.1.1 Orthogonality

17. Orthogonality

18. Orthogonality

19. Orthogonality

20. Orthogonality

21. 4.2.1.2 OFDM Modulation and Demodulation

22. 4.2.1.2 OFDM Modulation and Demodulation

23. 4.2.1.2 OFDM Modulation and Demodulation

24. 4.2.1.2 OFDM Modulation and Demodulation

25. 4.2.2 OFDM Guard Interval 4.2.2.1 Effect of Multipath Channel on OFDM Symbols

26. 4.2.2.1 Effect of Multipath Channel on OFDM Symbols

27. 4.2.2.1 Effect of Multipath Channel on OFDM Symbols

28. Cyclic Prefix (CP)

29. Cyclic Prefix (CP)

30. Cyclic Prefix (CP)

31. Cyclic Prefix (CP)

32. Cyclic Prefix (CP)

33. Cyclic Prefix (CP)

34. Cyclic Prefix (CP)

35. Cyclic Suffix (CS)

36. 4.2.3 OFDM Guard Band

37. 4.2.3 OFDM Guard Band

38. 4.2.3 OFDM Guard Band

39. 4.2.3 OFDM Guard Band

40. 4.2.3 OFDM Guard Band

41. 4.2.3 OFDM Guard Band

42. 4.2.3 OFDM Guard Band

43. 4.2.4 BER of OFDM Scheme

44. 4.2.4 BER of OFDM Scheme

45. 4.2.5 Water-Filling Algorithm for Frequency- Domain Link Adaptation

46. 4.2.5 Water-Filling Algorithm for Frequency- Domain Link Adaptation

47. 4.2.5 Water-Filling Algorithm for Frequency- Domain Link Adaptation

48. 4.2.5 Water-Filling Algorithm for Frequency- Domain Link Adaptation

49. 4.3 Coded OFDM

50. 4.3 Coded OFDM

51. 4.4 OFDMA: Multiple Access Extensions of OFDM

52. 4.4 OFDMA: Multiple Access Extensions of OFDM
Attributes
TDMA
FDMA
CDMA
Method
one user/subset of time slots/
all subcarriers
multiple users/same time/
subset of subcarriers
all users/same time/
Flexibility
variable number of time slots
variable number of subcarriers
variable number of spreading code
MAI
Intra-cell
none
None
Present
Inter-cell
present
MAI suppression
interference avoidance
(low frequency reuse factor)
interference averaging
multi-user detection
Others
small FFT size
isolated cell (wireless LAN)
large FFT size
cellular system
multi-user diversity
power concentration
inherent frequency diversity

53. 4.4.1 Resource Allocation-Subchannel Allocation Types

54. 4.4.1 Resource Allocation-Subchannel Allocation Types
Block
(Cluster)
Comb
(Interleaved)
Random
Method
Adjacent subcarriers
Equidistant subcarriers
Random subcarriers
Diversity
Frequency hopping required
Frequency diversity gain
Mobility
Slow
Fast
Channel Estimation
Simple
(coherence BW)
Whole band
Inter-cell Interference
Coordination required
Interference averaging

55. 4.4.2 Resource Allocation - Subchannelization
Subchannels
Name
Configuration
Usage
Diversity subchannel:
Downlink
PUSC
Scattered 48 tones
FCH/DL-MAP (Reuse 3), Data transmission
FUSC
Data transmission, Broadcasting
OFUSC
Diversity subchannel:
Uplink
6 distributed tiles
8 tones/tile
OPUSC
Band AMC:
downlink/uplink
(band AMC)
AMC
6 adjacent bins
8 tones/bin
Data transmission,
AMC, AAS

56. 4.4.2 Resource Allocation - Subchannelization
Parameters
PUSC
FUSC
OFUSC
Band AMC
No. of Left Guard Subcarriers 92 87 80
No. of Right Guard Subcarriers 91 86 79
No. of Used Subcarriers (no DC)
840
850
864
No. of DC Subcarrier (#512) 1
No. of Pilot Subcarriers
120 82 96
No. of Data Subcarriers
720
768
468
No. of Subcarriers per Subchannel 48
No. of Symbols per Subchannel 2
2, 3, 6
No. of Subchannels/symbol 30 16
Pilot Configuration
Common
Dedicated
Data Configuration
Distributed
Adjacent

57. 4.4.2 Resource Allocation - Subchannelization

58. 4.4.2 Resource Allocation - Subchannelization

59. 4.4.2 Resource Allocation - Subchannelization

60. 4.4.2 Resource Allocation - Subchannelization

61. 4.4.2 Resource Allocation - Subchannelization

62. 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.)
Coverage
wide coverage
small coverage
Mobility
Etc.
low latency
symmetric channel