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Preface xvii
Chapter 2 presents a general framework for performance analysis of ultra-dense
networks, particularly focusing on the impact of pathloss and multipath fading.
Under a pathloss model that incorporates both LoS and NLoS propagations and a
distance-dependent multi-path Rician fading model with a variant Rician K -factor,
the analytical expressions for both coverage probability and area spectral efficiency
are derived. Comparing the performance impact of LoS and NLoS transmissions in
interference-limited ultra-dense networks under Rician fading with that under Rayleigh
fading, the analytical and simulation results show that pathloss dominates the overall
system performance of ultra-dense networks, while the impact of multi-path fading is
quite limited and does not help to mitigate the performance loss caused by the many
LoS interfering links in ultra-dense networks, especially in single-input single-output
systems.
Chapter 3 considers the network densifications in wireless user devices, radio access
nodes, and cloud edge nodes, and presents a comprehensive introduction to mean field
game theory and tools, which is useful in the design and analysis of ultra-dense networks
with spatial-temporal dynamics. Following that, the authors present a survey of the lat-
est applications of mean field games in the 5G era in general (including device-to-device
communications and cloud-edge networks) and in 5G ultra-dense networks in partic-
ular, with a focus on resource management problems such as interference mitigation,
energy management, and caching.
Chapters 4 to 8 are grouped into Part II, which exploits the synergy between
ultra-dense networks and other key 5G candidate technologies.
Chapter 4 studies different schemes of wireless self-backhauling in ultra-dense net-
works, with a focus on the recently proposed in-band full-duplex self-backhauling. e
deployment of wireless backhauling, in general, helps to resolve the scalability problems
faced by wired backhaul connections, because wireless backhauling does not require
physical cables. e use of inband wireless self-backhauling is even more intriguing
than traditional wireless backhauling, because it enables the reuse of spectral resources
between radio access links and backhaul links. In this respect, no additional or ded-
icated frequency resources are required for the backhaul, and thus the in-band wire-
less self-backhauling will be commercially beneficial. ree different in-band wireless
self-backhauling schemes based on full-duplex or half-duplex operations are analyzed
and compared.
Chapter 5 aims to optimally leverage the dense deployment of small cells and massive
MIMO in future mobile networks. Using analytical tools from stochastic geometry, the
authors derive a tight approximation of the achievable downlink rate for a two-tier het-
erogeneous cellular network and use it to compare the performance between densifying
small cells and expanding base station antenna arrays. e results show that increas-
ing the density of small cells improves the downlink rate much faster than expanding
antenna arrays at base stations. However, when the small cell density exceeds a certain
threshold, the network capacity may start to deteriorate. On the contrary, the network
capacity keeps increasing with the expansion of base station antenna arrays until it
reaches an upper bound, which is caused by pilot contamination. is upper bound
surpasses the maximum network capacity achieved by the dense deployment of small
cells. Moreover, the authors provide practical design insights into the tradeoff between
the dense deployment of small cells and massive MIMO in future high-capacity wireless
networks.