Page 354 - 5G Basics - Core Network Aspects

1 Core network aspects

c) Transport layer: Port number is a typical resource for multi-connection. In addition, stream (session)
can also be a resource for multi-connection.
d) Application layer: Uniform resource locator (URL), domain name, session, access point name (APN),
IP multimedia private identity (IMPI), and IP multimedia public identity (IMPU) are the identity
resources for multi-connection.

6.1.2 Resource attributes related to multi-connection

This clause describes the resource attributes. These resource attributes are required to describe features and
usage.

a) PHY/MAC layer: The resources for multi-connection in the PHY/MAC layer are identified as access
network, access technology, network interface, radio access technologies (RAT) and wireless
channel. The attributes of each resource are defined as follows:
i) Access network: The access network is related to the access technology and RAT. One specific
access network may be operated by one access technology or several access technologies. In
addition, a service provider may manage several access networks. Usually, if an access network
is referred to as a network that connects access technologies to the core network [ITU-T
Q.1742.1], the characteristics of the access network can be determined by the service provider,
including the access technologies for each access network.
ii) Access technology: The access technology is related to the access network and the service
provider. To provide multi-connection, service providers can use one same or different access
technologies.
iii) Network interface: The network interface is directly related to access the technology. A specific
access technology may restrict the characteristics of a network interface. For a multi-connection
node, multiple network interfaces are directly used simultaneously. For a network interface of
the multi-connection, there can be a physical network interface and a logical/virtual network
interface. A network interface is a logical interface to the upper layer (e.g., network layer) and
is related to the establishment of a network layer connection.
iv) Radio access technologies (RAT) and wireless channels: These multi-connection resources are
related only to wireless access technology. The wireless specific attribute of these resources is
used radio frequency or used bandwidth. For example, WLAN (Wi-Fi) uses an ISM band (2.4 GHz
and 5 GHz) and 20 MHz/40 MHz bandwidth per wireless channel. To create a multi-connection,
the used wireless access technology and channel information should be considered.

b) Network layer: The resources for multi-connection in the network layer are identified as IPv4
address, IPv6 address, prefix, flow label and extension header. The attributes of each resource are
defined as follows.
i) IPv4 address: The IP address is a basic resource in the network layer needed to route to the next
hop and to identify the point of attachment of the host. IPv4 addresses are composed of 32 bits
and their availability can be limited. The usage of IPv4 addresses can be categorized as local-
scope usage or global-scope usage.
ii) IPv6 address, prefix and flow label: In contrast to IPv4 addresses, IPv6 addresses are composed
of 128 bits and their availability is relatively sufficient. The usage of IPv6 address is categorized
as local-scope usage or global-scope usage. Regarding the prefix, the 64-bit length prefix
identifies the network domain to be used to configure the IPv6 address. The prefix is managed
hierarchically by each router. Regarding the flow label, each connection is distinguished by IPv6
address as well as flow label for specific applications. The flow label is a 20-bit field in the IPv6
header and is used to label the sequences of packets.
c) Transport layer: The resources for multi-connection in the transport layer are identified as port
number and stream (session) number. The attributes of each resource are defined as follows:

i) Port number: The port number is not directly related to multi-connection because the port
number is used to distinguish data packet through proper applications. But, if multi-connection

344