1. Aspects of modern wireless communications
Lecturer: Prof. Dr. János LEVENDOVSZKY
EU-USA Atlantis Programme - Sensing Technology and Robotic Systems project
FIT & Budapest University of Technology and Economics

2. Outline Digital baseband modulation PAM InterSymbol Interference (ISI)
Matched filter receivers
BER-SNR

3. The scheme
Binary info sequence
Modulator
Radio channel
Distortion, interference and noise
Receiver (demod and detection)
Received binary info sequence
Analog waveform
+1,+1,-1,+1 T
Data speed = 1/T t
Challenge: What is the best waveform fitting the channel, providing band-efficient and reliable data transfer ?

4. The problem with waveforms
x(t) t
h(t)
H(f) f t
This is not a band limited communication !!!

5. The underlying problem lies with the properties of Fourier transform
H(f) f t
Finite support
Infinite support

6. An example
-0.5T
0.5T 1
h(t) t
Infinite support

7. The problem with waveforms
x(t) t T
H(f) f
This is not a band limited communication !!!