Communications III

Wireless communications is today's predominant network access technology, be it Bluetooth, WiFi, or Mobile Cellular Systems such as GSM, UMTS, LTE or 5G. Coding and signal processing for wireless communications allows to seamlessly connect devices to computers as cable replacement, to connect people across cities and counties, and to communicate to distant space probes. This lecture introduces physical layer technologies and modulation as well as detection schemes to communicate reliably at different data rates, different distances and rapidly changing channel conditions determined by the involved vehicle speeds and multipath propagation characteristics.

1 Overview
1.1 The capacity crunch
1.2 Wireless network structure
1.3 Data rates and spectral landscape
1.4 A simple wireless communication link
1.5 Technical milestones and future trends

2 Wireless communication channel
2.1 Path loss: Describing long-term channel variations
2.1.1 Free-space path loss
2.1.2 “Breakpoint” path loss model (two-path model)
2.2 Statistical characterization of channel variations
2.2.1 Large-scale channel variations
2.2.2 Small-scale channel variations
2.2.3 Combined fading margin
2.3 Noise
2.4 Receiver sensitivity
2.5 Link budget revisited
2.6 Stochastic channel models
2.6.1 Frequency-selective fading: Delay spread and coherence bandwidth
2.6.2 Time-selective fading: Doppler spread and coherence time
2.6.3 Putting both together: General wideband channels
2.7 Channel capacity

3 Single carrier-based wireless systems
3.1 Transmitter
3.1.1 PAM/QAM constellation mapping
3.1.2 Transmit filter and spectrum
3.2 Flat-fading Channel
3.3 Receiver
3.3.1 Channel estimation and coherent detection
3.3.2 Constellation symbol (QAM-) demapping
3.4 Physical layer performance measures
3.5 Diversity in wireless communications
3.6 Mitigating multipath propagation by equalization
3.6.1 Overview of different equalization schemes
3.7 Linear equalization
3.7.1 Ideal equalization
3.7.2 Truncated Zero-Forcing (ZF) equalization
3.7.3 Truncated Zero-Forcing (ZF), optimized
3.7.4 Minimum Mean Squared Error (MMSE)
3.8 Non-linear equalization
3.8.1 Maximum likelihood sequence estimation (MLSE)
3.8.2 Simplifying the likelihood function for the AWGN channel
3.8.3 Multipath Channel as Shift Register
3.8.4 The Viterbi Algorithm
3.8.5 Example of the Viterbi algorithm

4 Multicarrier-based wireless systems
4.1 Motivation
4.2 Recap: Single carrier modulation
4.3 From single- to multi-carrier modulation
4.4 Performance over multipath channels
4.5 Cyclic prefix (guard interval)
4.6 Parameters of wireless OFDM systems
4.7 Discrete-time multicarrier modulation/demodulation (for your interest)

A Appendix
A.1 Some more path loss models
A.1.1 Okumura-Hata model
A.1.2 Motley-Keenan indoor path loss model
A.2 Interference in unlicensed ISM band
A.3 Symbol and bit-error probabilities of some modulation schemes