1. Welcome to Simulation of communication systems
DT001A (7,5 credit points) or
DT026A (project part+labs 4,5 out of 9 points)
and

2. A project course about MATLAB with SIMULINK and Communications Blockset…
MATLAB = Matrix Laboratory.
Tool for numerical calculation and visualization. Commonly used for simulation of the communication system physical layer, signal and image processing research, etc.
SIMULINK: Toolbox in Matlab
that allows graphical data-flow oriented programming.

3. …and about Network Simulation using tools such as Prowler, NS/3, etc

4. Aim of the course
To prepare the student for thesis project and work in the area of telecommunciations development and research.
To give experience of performance analysis of communication systems and algorithms, at the physical layer and datalink layer.
To give experience of simulation tools such as MATLAB, SIMULINK and/or Opnet.
This may include modelling and simulation of traffic sources, channel models, modulation schemes, error coding schemes, equalizers, algorithms, protocols and network topologies.
A real-world project is studied within an application area such as wireless sensor networks, cellular communications, modems for broadband access, wireless networks, short-range communication, digital TV transmission, IP-TV or IP-telephony.

5. Prerequisites
Computer Networks A 7.5 ECTS credits or Multimedia and communication systems B 6 ECTS credits
Wireless Internet Access B or Machine-to-Machine communication AV
Computer Engineering AB-level, 30 ECTS credits, incl programming
TCP/IP networking
Mathematical statistics
Other helpful courses:
Mathematical modelling or Stochastic processes/Markov processes/Queueing theory
Transform theory or Signals and systems
Analog electronics or Circuit theory
Signals and systems, 7.5 ECTS credits.

6. Litterature
Matlab, Simulink and NS/3 documentation will be provided electronically.
Please repeat physical layer issues and datalink layer issues in books on Computer Networks, Machine-to-machine communications and/or Wireless Internet Access.

7. Requirements All lectures and supervision lessons are mandatory.
You should attend 80% of the mandatory lessons.
You are expected to devote 20 hours/week to this course.
Qiuzzes (multiple choice tests): At least 70% correct answers.
Lab: About 20 hours of work.
Homework problem.
Oral presentations with discussion
Project report

8. Requirements on the project
Review at least one research paper, and describe some standard and some existing simulation model.
Simulate a communications standard, or check the simulations made in a research paper.
At least modify an existing simulation model, for exampel a Simulink or Matlab demo, or build a model of your own (more difficult)
Produce some plots for several parameter cases, showing for example BER, bit rate or delay as function of at least two different parameters, for example SNR, facing model, modulation scheme, etc.
The simulation results should be stable (the plots smooth and not jerky), i.e simulate sufficiently long simulation time, or take the average of sufficiently large number of simulations.
Draw some interesting conclusions from this.

9. Grading is based on Keeping deadlines. Quizzes.
Showing good understanding when answering questions from teachers and other students about your presentations.
For grade B or A, the following is also required:
Mathematical modelling of stochastic processes.
Extensive own code.
Research relevance. (Required for grade A or B.)

10. Typical disposition of final project report
1. Introduction (Assignment 6. )
(Problem motivation and formulation – incl concrete parameters)
2. Theory (Assignemnt 3)
(Standards, on going development, previous research to repeat or compare with)
3. Existing simulation model to start out from or compare with (Assignment 3)
4. Own simulation model (Assignment 6)
5. Simulation results (Assignment 7)
6. Conclusions (Assignement 7)
Answer intro problems, discuss reliability fo the result, try to explain result and differences from previous research, suggest future research
See our template for technical reports

11. Assignment 1: Theory repetition
The first assignment consists of old exam problems in Computer Networks A, Wireless Internet access B and Telecommunications B.
Deadline: Friday course week 2. Be prepared to present your answers on the whiteboard.

12. Assignment 2: Simulink lab exercize
Takes about hours to do.
Deadline: Course week 3

13. Assignment 3: Present a standard and an existing simulation model – that you later will simulate and evaluate
Essentially chapter 2 (theory) and 3 (existing model that you start out from) of your report. Examples
NFC (Simulink model made by previous years students – see Mathworks file archive).
IEEE a WLAN Physical Layer. Also describe newer standards n, ac.
WCDMA Coding and Multiplexing.
WCDMA Spreading and Modulation 
WCDMA End-to-end Physical Layer.
MIMO for example in IEEE n MIMO, link adap.
Ultrawideband (UWB/wireless USB). See mathworks file archive. ZigBee Simulink or Prowler model and IEEE g (smart grid). See mathworks file central. .
ZigBee Prowler model and Multihop routing protocols (Prowler model) . You may demonstrate simulink model (see Matlab file central) or Prowler model. Perhaps you can add cooperative diversity.
Mobile Wimax – Link adaptation and (H)ARQ:
Long-term evolution (LTE) Phy Downlink with spatial modeling. Also describe LTE-A. Long-term evolution (LTE) and eMBMS
Line codes. Comparison of RZ, NRZ, AMI, Manchester coding (used in 10 Mbps Ethernet), 4B5B (used in 100Base-TX Ethernet) and PAM5 (used in 1000Base-T Gigabit Ethernet): For a code demonstrating RZ, NRZ, AMI and Manchester, see    This code also requires this MATLAB function:    During the rest of the project you may further develope the code to deal with 4B5B and PAM5, and to measure the bit error rate.
Compare mutlihop routing algorithms. E.g. using Prowler.
Compare two wireless sensor network MAC protocols. E.g. CDMA/CA vs Dynamic TDMA. Acoustic modem (develop new model – to be used by students e.g. in a competition on highest data rate)
Mobile system simulator: Several moving users. Two base stations with handover or roaming (wifi or LTE). Calculate total throughput and spectral efficiency in bit/s/Hz/transmitter, and also outage probability. Try to maximize efficiency for a maximum outage of 5%.
WLAN Localizating - e.g. based on SS fingerprinting and datamining
Localizationg using the IEEE v or IEEE standard. Packet data models: Compare models like Poisson traffic versus self-similar traffic. When does it give different result.
Optimized scheduling: Compare the PARPS algorithm with an optimized packet scheduling.
Acoustic QR code (continue on project by previous year’s students)
5G (or LTE) simulation in Simulink and/or Ns/3.

14. Assignment 3 (cont.)
Oral presentation: Course week 5. Talk 5-10 minutes per person.
Everyone should take notes and give to the teacher, and everyone should ask questions and discuss the topic.
Present:
A standard (mention things like radio frequency, bandwidth, bit rate, modulation, error control method, multiplex method, multiple-access protocol, new/future versions)
New versions of the standard or ongoing development
Screen dumps – or demonstration of - an existing simulation
Mathematical models, statistical distributions and simulation parameters used in the existing simulation model
Differences between simulation and a full implementation
For higher grades:
Also cite a related research paper or a textbook, for example a simulation method with results. See scholar.google.com or library.
Within one week after that: Submit report chapter 2 (theory/previous research) and chapter 3 (existing model)

15. Assignment 4: Quizzes Basic concepts, Matlab and Simulink concepts
Requirement: At least 70% correct answers.
You can do them over and over again until the deadline.

16. Assignment 5: Prowler lab
Zigbee and multihop simulation in Prowler.
Takes about 4 hours to do.

17. Assignment 6: Present project suggestion
Oral presentation course week 6.
Present
Problem formulation (chapter 1) – what to parameters to evaluate
Cite simulation done in a research paper (if you have not done so)
Planned own modification or development of model (chapter 4)
Submit or show report chapters 1 and 4 before christmas.

18. Assignment 7: Final project presentation
Demonstrate simulation code to teacher (and also in report appendice)
Oral presentation in mid-January of
Results (chapter 5): Plot performance for several cases.
Conclusions (chapter 6). Discuss similarities and differences from result in a cited research paper.
Provide a preliminary report when you give your oral presentation.

19. F2. programmeringsteknik och Matlab
MATLAB
MATLAB = Matrix Laboratory.
Tool for numerical calculation and visualization. Commonly used for simulation of the communication system physical layer, signal and image processing research, etc.
KTH, NADA, Vahid Mosavat

20. This is how MATLAB looks like
F2. programmeringsteknik och Matlab
This is how MATLAB looks like
Workspace
Command history
Command window
KTH, NADA, Vahid Mosavat

21. F2. programmeringsteknik och Matlab
More MATLAB windows
Figure window
Array editor
M-file editor
KTH, NADA, Vahid Mosavat

22. How to get help in MATLAB?
F2. programmeringsteknik och Matlab
How to get help in MATLAB?
help functionsname
Shows unformatted text
doc funktionsnamn
Shows HTML documentation
in a browser
KTH, NADA, Vahid Mosavat

23. SIMULINK SIMULINK: Toolbox in Matlab
that allows graphical data-flow oriented programming.
(Demo of WLAN PHY model.)

24. Repetition of some basic concepts
Frequency spectrum
Digitalisation, source coding
Error coding
Modulation
Multiple-access methods
Base-band model
Distorsion, noise
Signal-to-noise ratio
Bit-error ratio
Statistics

25. Repetition of some basic concepts

26. Some statistical distributions

27. Gaussian noise
Voltage
Time

28. Gaussian = Normal distribution
Probability density funciton

29. Additive White Gaussian Noise (AWGN) channel
White noise = wideband (unfiltered) noise with constant noise density in Watt/Hertz
Pink noise = lowpass-filtered noise.
Additive = linear mixing.
Signal
Noisy signal +
Noise source

30. Bernoulli distribution
Random sequence of independent 0:s and 1:s.

31. Exponential distribution
Commonly used for time between phone calls and length of phone
calls. Simple model for calculation and simulation,
but does not reflect data traffic bursty nature.

32. Multi-path propagation

33. Rayleigh distribution
Model of rayleigh fading, i.e. amplitude gain caused by multi-path propagation with no line-of-sight

34. More commons distributions
Ricean distribution (fading with line-of-sight)
Poisson distribution (number of phone calls during a phone call)
Self-similar process (bursty data traffic)
Rectangular distribution
Discrete distributions, for example the distribution of a dice

35. Digitalization

36. PCM = Pulse Code Modulation = Digital transmission of analogue signals
Number exemples from PSTN = the public telephone network 1
DA-
converter
Anti aliasing-
filter
Sampler
Interpolation
filter
AD-converter with
seerial output
Loudspeaker
Microphone
8 bit per sampel
i.e bps
per phone call
28 = 256 voltage levels Hz
band pass filter. Stops everything over 4000Hz.
8000
sampels
per sec

37. Aliasing

38. Quantization noice

40. Digital transmission

41. Distorsion

42. Effect of attenuation, distortion, and noise on transmitted signal.

43. Point-to-point communication
Layer 6 2 1 7
Mikrofon
Högtalare
Source coding
Source decoding
Digitalizating compression
0110
Error management
Error control .
Bitfel
NACK
Flow control
ACK
Modulation
Demodulation

44. Digital modulation methods
Binary signal
ASK = Amplitude Shift Keying (AM)
FSK = Frequency Shift Keying (FM)
PSK = Phase Shift Keying (PSK)

45. 8QAM example:
Below you find eight symbols used for a so called 8QAM modem (QAM=Quadrature Amplitude Modulation). The symbols in the first row represent the messages 000, 001, 011 and 010 respectively (from left to right). The second row representents 100, 101, 111 and 110.

46. Example 2 cont.

47. Bit rate vs baud rate Bit rate in bit/s:
Where M is the number of symbols and fs is the symbol rate in baud or symbols/s.

48. Bit and baud rate comparison
Modulation
Units
Bits /symbol
Baud rate
Bit Rate
ASK, FSK, 2-PSK
Bit 1 N
4-PSK, 4-QAM
Dibit 2 2N
8-PSK, 8-QAM
Tribit 3 3N
16-QAM
Quadbit 4 4N
32-QAM
Pentabit 5 5N
64-QAM
Hexabit 6 6N
128-QAM
Septabit 7 7N
256-QAM
Octabit 8 8N

49. Figure 5.14 The 4-QAM and 8-QAM constellations
Q (Quadrature phase)
Q (Quadrature phase)
I (Inphase)
I (Inphase)

50. Sine wave example
Complex representation
5 Volt
л/2 radians = 90º I

51. Inphase and quadrature phase signal
Sine wave as reference (inphase) signal:
Cosine wave as reference (inphase) signal:

52. Complex baseband representationjQ
C = I+jQ
Amplitude:
Phase:
RF signal (physical bandpass signal, if a cosine is reference signal):
|C| C
Arg C I

53. Equivalent baseband signal

54. Figure 5.11 The 4-PSK characteristics

55. Figure 5.12 The 8-PSK characteristics

56. Figure 5.16 16-QAM constellations

57. Spectrum of ASK, PSK and QAM signal

59. Figure 3.9 Three harmonics

60. Figure 3.10 Adding first three harmonics

61. Square wave with frequency fo
Example: Square Wave
Square wave with frequency fo
Component 1:
Component 3:
Component 5: . .

62. Figure 3.11 Frequency spectrum comparison

63. Filtering the Signal Types of filters Low pass Band pass High pass
Filtering is equivalent to cutting all the frequiencies outside the band of the filter
Types of filters
Low pass
Band pass
High pass
Low pass
H(f)
INPUT
S1(f)
OUTPUT
S2(f)= H(f)*S1(f)
H(f) f
Band pass
H(f)
INPUT
S1(f)
OUTPUT
S2(f)= H(f)*S1(f)
H(f) f
High pass
H(f)
INPUT
S1(f)
H(f)
OUTPUT
S2(f)= H(f)*S1(f) f

64. Figure 6.4 FDM (Frequency division multiplex)

65. Figure 6.5 FDM demultiplexing example

66. Figure 6.19 Time division multiplex (TDM) in the american telephone network

67. Multi-path propagation

68. Multiple access = channel access
Several transmitters sharing the same physical medium, for example wireless network, bus network or bus network.
Based on
A physical layer multiplexing scheme
A data link layer MAC protocol (medium access control) that avoids collisions, etc.
Examples:
TDMA (time division multiple-access) based on TDM
FDMA (frequency division multiple-access) based on FDM
CDMA based on spread spectrum multiplexing
CSMA (carrier sense multiple-access) based on packet switching = statistical multiplexing
OFDMA

69. Cellular telephony generations
1G: (E.g. NMT 1981) Analog, FDMA circuit switched.
2G: (E.g. GSM 1991) Digital, FDMA+TDMA, 8 timeslots, circuit switched.
2.5G: (GPRS) Packet switched = statistical multiplexing. The old circuit switched infrastructure is kept.
3G: (e.g. WCDMA) FDMA + CDMA (= spread spectrum).
4G: (E.g. 3gpp LTE) All-IP. OFDM or similar.

70. DS-CDMA = Direct Sequence Code Division Multiple Access
Spread spectrum
DS-CDMA = Direct Sequence Code Division Multiple Access
Chip sequencies

71. Figure Encoding rules

72. Figure 13.16 CDMA multiplexer

73. Figure 13.17 CDMA demultiplexer

74. Figure 9.1 Discrete Multi Tone (DMT)
Essentially the same thing as OFDM
Used in ADSL modems

75. Figure 9.2 ADSL Bandwidth division

76. A simple example: 4 sub-carriers
OFDM modulation
A simple example: 4 sub-carriers
8 PSK

77. Technical data for DAB and DVB-T

78. Orthogonal Frequency Division Multiplex (OFDM)
Summary of advantages
Can easily adapt to severe channel conditions without complex equalization
Robust against narrow-band co-channel interference
Robust against Intersymbol interference (ISI) and fading caused by multipath propagation
High spectral efficiency
Efficient implementation using FFT
Low sensitivity to time synchronization errors
Tuned sub-channel receiver filters are not required (unlike conventional FDM)
Facilitates Single Frequency Networks, i.e. transmitter macrodiversity.
Summary of disadvantages
Sensitive to Doppler shift.
Sensitive to frequency synchronization problems.
Inefficient transmitter power consumption, due to linear power amplifier requirement.

79. Bit error rate (BER) = Bit error probability = Pb
Packet error rate (PER) = Packet error probability for packet length N bits:
Pp = 1 – (1-Pb)N

80. Error-correcting codes (ECC), also known as Forward-error correcting codes (FCC)
A block code converts a fixed length of K data bits to a fixed length N codeword, where N > K.
A convolutions code inserts redundant bits into the bit-stream. Code rate ¾ means that for every 3 information bit, totally 4 are transferred, i.e. every forth of the transferred bits is redundant.

81. Bit rates Gross bit rate = Transmission rate.
Symbol rate = Baud rate ≤ Gross bit rate
In spread spectrum: Chip rate ≥ Bit rate ≥ Symbol rate.
In FEC: Net bit rate = Information rate = Useful bit rate ≤ Code rate * Gross bit rate
Maximum throughput ≤ Net bit rate
Goodput ≤ Throughput

82. Nyquist formula
Gives the gross bit rate,without taking noise into consideration:
Symbol rate < Bandwidth*2
Bit rate < Bandwidth * 2log M
The above can be reached for line coding (base band transmission) and so called single-sideband modulation. Howeverm in practice most digital modulation methods give:
Symbol rate = Bandwidth

83. Signal to noise ratios
S/N= SNR = Signal-to-noise ratio. Often same thing as C/N=CNR = Carrier-to-noise ratio
SNR in dB = 10 log10 (S/N)
S/I = SIR = Signal-to-interference ratio. Often the same thing as C/I=CIR = Carrier-to-interference ratio. I is the cross-talk power.
CINR = C/(I+N) = Carrier-to-noise and interference ratio
Eb/N0 = Bit-energy (Power in watt divided by bitrate) divided by Noise density (in Watt per Hertz)
Es/N0 = Symbol-energy (Power in Watt divided by bitrate) divided by Noise density (in Watt per Hertz)

84. Shannon-Heartly formula
Gives the channel capacity, i.e. the maximum information rate (useful bit rate) excluding bit error rate.
I=B log2 (1+C/N)
Where C/N is carrier-to-noise ratio (sometimes called S/N)