Page 340 - From GMS to LTE

326 From GSM to LTE-Advanced Pro and 5G

and specifically the air interface, often contradicting the requirements of MBB. While
many machine‐to‐machine applications require only little bandwidth and are able to
cope with long data‐transfer delays, they only have small batteries that must last for
weeks, months or even years. This means that an air interface and procedures are
required that make sporadic communication and long idle times as power efficient as
possible. On the other side of the application spectrum, vehicle‐to‐vehicle communica-
tion is very time sensitive, i.e. data must be transferred with very low latency while
power consumption plays a less important role as power is abundant.
Many enhancements have been made to LTE over the years to address such scenarios,
such as NB‐IoT (Internet of Things) for power‐efficient low‐datarate communication
on the one end of the application spectrum and carrier aggregation for high data trans-
fer rates and low latency on the other. However, due to the rigid structure of the LTE air
interface and core network it is difficult to fully address non‐mobile broadband sce-
narios with the current LTE radio interface and network setup.
Furthermore, as overall bandwidth demands and individual datarate requirements
keep rising, new frequency bands need to be tapped to create an evolution path for the
mobile broadband use case as well. This necessitates that transmission costs per bit
continue to fall. This in turn requires cheaper base station hardware and keeping energy
consumption of the network and especially the base stations in check as more and more
data is transferred. This is especially the case in small‐cell scenarios due to the potentially
large number of small‐cell base stations that have to be deployed to increase capacity of
networks in the future. Keeping power requirements in check as datarates are rising is
nothing new, however. Base stations today transfer many orders of magnitude more
data compared to a GSM base station while power consumption is still in the same
order of magnitude as 30 years ago.
To go beyond what LTE has to offer for the different usage scenarios, LTE’s successor
system has to have flexibility built in from the radio interface to the core network. This
is a significant difference from the LTE radio and core network today, which is built
around strict timing requirements and network configurations. In general, 5G stand-
ardization in 3GPP is split into two streams. The first stream focuses on the next gen-
eration air interface and radio network and is referred to as ‘New Radio’ or NR for short.
The second stream focuses on a new core network design for 5G, which is referred to as
‘Next Generation Core Network’ (NGCN). In December 2016, 3GPP studies for 5G
were fully underway. While not yet far advanced at the time of publication, companies
had started to agree on specific designs and features in the 3GPP 38 series of docu-
ments, which contains the technical reports (TRs) for 5G [46]. These are likely to be
found in 3GPP Release 15 which will be the first 3GPP 5G New Radio (NR) and Next
Generation Core Network (NGCN) release and is set to be finalized in 2018. The
following sections give an overview of those features.

4.21.1 New Radio for 5G
As discussed in the introduction the new radio network and air interface must address
different applications ranging from slow but low power consumption applications to
ultra‐fast data transmissions with latency similar to LTE today to medium datarate
applications which, however, require a very low latency. 3GPP wants to address
these conflicting requirements by designing a very flexible radio interface that can have