Part I. Getting Started: 1. Introduction; 2. Modelling and analysis of ultra-dense wireless networks; 3. Performance analysis of traditional sparse and dense wireless networks; Part II. Fundamentals of Ultra-Dense Small Cell Networks: 4. The impact of line-of-sight transmissions on ultra-dense wireless networks; 5. The impact of antenna heights on ultra-dense wireless networks; 6. The impact of a finite user density on ultra-dense wireless networks; 7. The impact of ultra-dense wireless networks on multi-user diversity; Part III. Capacity Scaling Law: 8. The ultra-dense wireless networks capacity scaling law; 9. System-level network optimization; Part IV. Dynamic Time Division Duplexing: 10. Uplink performance analysis of ultra-dense networks; 11. Dynamic time division duplexing ultra-dense wireless communication networks.