5G Mobile Networks: Requirements, Enabling Technologies, and Research Activities 43
awareness, real‐time interactions, mobility support, geographical distribution, and the
predominance of wireless access [27].
Although both MEC and FC are extremely fit for the development of the 5G system,
there are several research issues that need to be further explored, such as the interworking
between edge clouds, between edge clouds and centralized clouds, mobility management to allow users to seamlessly access edge applications, and other open challenges
such as security and performance.
Figure 2.7 (a) Cloud‐RAN concept, adapted from [23]; and (b) RANaaS concept, adapted from [24].
BBU
Pool
Fiber
Fronthaul
RRHs
RRH
UE
L1/L2/L3/O&M L1/L2/L3/O&M L1/L2/L3/O&M
(a)
Adm./ Conf.
Control
RRM
MAC
PHY
RF
Flexible Functional Split
Netw.
Mgmt.
Netw.
Mgmt.
Adm./ Conf.
Control
RRM
MAC
PHY
RF
LTE
Implementation
C-RAN
Implementation
RANaaS
Centrally executed
Executed
at RRH
Centrally
executed
(b)
Executed at BS