Page 325 - From GMS to LTE

Long Term Evolution (LTE) and LTE-Advanced Pro 311

about which networks they can reach. This information is then used on each router
to decide if an update to the routing table is necessary. When the routing table is
altered due to a BGP update from another router, the router will then also send out
information to its downstream routers to inform them of the change. In other words,
routing changes propagate through the Internet and each router is responsible on its
own for maintaining the routing table based on routing signaling messages it receives
from other routers. For network administrators this means that they have to have a
very good understanding of the status of each router in their network, as each
updates its routing table autonomously based on the information it receives from
other routers. Routers from different manufacturers have different administration
interfaces and different ways to handle routing updates, which adds additional com-
plexity for network administrators. To make the administration process simpler and
more deterministic, the idea behind Software‐Defined Networking (SDN) is to
remove the proprietary administration interface and automate local modifications of
the routing table in the routers, and perform these tasks in a single application on a
centralized network configuration platform. Routers would only forward packets
according to the rules they receive from the centralized configuration platform and
according to the routing table also received from the centralized platform. In addi-
tion, changes to the routing table are made in a central place instead of in a decen-
tralized manner in each router. The interface SDN uses for this purpose is described
in the OpenFlow specification which is standardized by the Open Network
Foundation (ONF). A standardized interface enables network administrators to use
any kind of centralized configuration and management software independent of the
manufacturers of the routing equipment they use in their network. Router manufac-
turers can thus concentrate on designing efficient router hardware and the software
required for inspecting, modifying and forwarding packets.

4.19 Machine Type Communication and the Internet
of Things

When LTE was initially designed the main requirement was that it should enable high
data throughput to and from mobile devices far beyond the capabilities of UMTS. While
this has been impressively achieved the resulting network architecture does not work
equally well for emerging Internet of Things (IoT) devices such as wearables, industrial
sensors, home appliances, etc. Such devices are expected to be very small, to transmit
only small amounts of data and to be equipped only with a very small battery that must
supply energy for weeks, months or even years of operation. Furthermore such devices
are often located in places that are not reached by networks today such as basements
and industrial environments. In home environments, IoT devices can make use of local
area networks or a central IoT hub close by that interacts with small IoT devices and
forwards the data over Wi‐Fi, cable, DSL and fiber. In other cases local area networks
connecting to the Internet are not available and it would therefore be beneficial to use a
cellular network as backhaul.
While GSM was and still is used today for many applications, it is a legacy technology
and many network operators would like to switch it off in the coming years [35]. This
leaves proprietary technologies or LTE as connectivity options for the future for such