Prerequisites & Notation

Before You Begin

This chapter introduces the cloud-RAN (C-RAN) / fog-RAN architecture and the NDT framework for cache-aided edge networks. Prerequisites include basic C-RAN system concepts and the MAN baseline.

The MAN scheme and caching gain (Ch 2)(Review ch02)
Self-check: Can you state $R = K(1-\mu)/(1+K\mu)$ and the coded multicasting gain?
Cache-aided MIMO BC and DoF (Ch 5)(Review ch05)
Self-check: Can you sketch the Lampiris-Caire scheme for $K, L, M$ ?
Cloud-RAN basics: ENs, fronthaul, functional split(Review ch18)
Self-check: What is the difference between CPRI/eCPRI and IP-based fronthaul?
Latency analysis and DoF
Self-check: For a K-user MIMO BC, how does delivery time scale with SNR?
Functional decomposition: PDCP/RLC/MAC/PHY(Review ch24)
Self-check: Which PHY-layer operations are performed at the cloud vs. EN in a C-RAN split?

Notation for This Chapter

Symbols for the cloud-RAN + cache model and the NDT framework.

Symbol	Meaning	Introduced
$K$	Number of users in the downlink	s01
$N_\text{EN}$	Number of edge nodes (base stations)	s01
$M$	Per-EN cache size in file units	s01
$C_F$	Per-EN fronthaul capacity in files per channel use	s01
$\Delta$	Normalized delivery time	s02
$T(\text{SNR})$	Delivery time in channel uses, function of SNR	s02
$\mu$	Per-EN memory fraction $M/N$	s01
$t$	Aggregate caching gain $t = N_{\text{EN}} M/N$	s02

← Ch 7 The Cloud-RAN Architecture with Edge Caching