Page 344 - From GMS to LTE

330 From GSM to LTE-Advanced Pro and 5G

(a) (b)

gNB eNB CP gNB

CP UP CP UP CP UP

Enhanced LTE ‘legacy’ Enhanced LTE ‘legacy’
core network core network

Initial setup for ‘fixed-mobile’ Initial setup for enhanced
applications mobile broadband

Figure 4.34 Standalone (SA) and Non‐Standalone (NSA) 5G radio network configuration.

4.21.3 Core Network Evolution for 5G
Both options described above are likely to be connected to an enhanced LTE core
network as they extend today’s major use case, i.e. mobile broadband. For other 5G use
cases that are likely to be implemented later, such as massive narrowband‐IoT and ultra‐
low latency communication, a new and more flexible next‐generation core network will
be required. One term often mentioned in this regard is ‘network slicing’. One of the
major features of network slicing is to virtualize control‐ and user‐plane functions of the
mobile core network, as described earlier in the section on Network Function
Virtualization (NFV). By using virtualized network components it becomes possible to
create individual core network slices for different kinds of applications. For example,
core network components optimized for serving mobile broadband customers while
other core network slices are optimized toward energy‐efficient low‐speed communica-
tion (NB‐IoT) or reduced‐latency applications (such as car‐to‐car communication) can
be envisaged. All slices connect to the same radio network and use or share the same or
different resources. The core network slice dealing with NB‐IoT, for example, would
request the resources with the required QoS for this type of application from the radio
network it requires. The gNBs in turn would then assign more or less capacity on the air
interface in a part of the spectrum optimized for the application and adapt the transmis-
sion and reception areas on the air interface accordingly, as described above. For reasons
of complexity and the market for such applications still being in its early stages, it is likely
that such concepts will be implemented in practice well beyond the 2020 time frame.

Questions

1. How many subcarriers are used for a 10 MHz FDD‐LTE channel?

2. What is the difference between an S1 and an X2 handover?