Prerequisites
Before You Begin
This chapter builds on linear algebra (Chapter 1), probability theory (Chapter 2), wireless channel modelling (Chapter 6), digital modulation (Chapter 8), and detection/estimation in fading (Chapter 9). Diversity techniques exploit independent fading across space, time, or frequency to combat the severe performance degradation caused by deep fades.
- Vectors, norms, and inner products(Review ch01)
Self-check: Can you compute the norm of a complex channel vector and express as ?
- Random variables, expectation, and independence(Review ch02)
Self-check: Can you compute when are independent and identically distributed random variables?
- Chi-squared and exponential distributions(Review ch02)
Self-check: Do you know the PDF of a sum of independent exponential random variables (Erlang distribution) and its connection to the chi-squared distribution with degrees of freedom?
- Rayleigh and Rician fading models(Review ch06)
Self-check: Can you state the PDF of the instantaneous SNR for a single Rayleigh fading link and compute ?
- Coherence time, coherence bandwidth, and fading correlation(Review ch06)
Self-check: Can you explain when two channel realisations are approximately independent based on the coherence time and coherence bandwidth ?
- BER in AWGN and Rayleigh fading(Review ch08)
Self-check: Can you state the BER for BPSK in AWGN () and in Rayleigh fading ( at high SNR)?
- Detection and estimation in fading channels(Review ch09)
Self-check: Can you explain the difference between coherent detection (requires CSI) and non-coherent detection, and state the pairwise error probability in fading?
Chapter 10 Notation
Key symbols introduced or heavily used in this chapter.
| Symbol | Meaning | Introduced |
|---|---|---|
| Number of diversity branches | s01 | |
| Diversity order () | s01 | |
| Instantaneous SNR on the -th diversity branch | s01 | |
| Average SNR per branch | s01 | |
| Output SNR of selection combining () | s02 | |
| Output SNR of equal-gain combining | s02 | |
| Output SNR of maximal-ratio combining () | s02 | |
| Complex channel gain on the -th branch | s02 | |
| Space-time channel matrix (Alamouti and STBC context) | s03 | |
| Parameter in MRC BER expressions | s02 | |
| Coherence time of the channel | s04 | |
| Coherence bandwidth of the channel | s04 | |
| Number of transmit antennas | s03 | |
| Number of receive antennas | s02 |