Lecture #2 - Requirements Flashcards
Name the different architecture domains.
- Distributed/ Centralised RAN
- Management, control, user plane
- Access and core network
- Individual core network functions.
- Core network and applications.
Define a network function and network function service, and how their communication framework (compared to a reference point based)
A network function refers to a specific task or operation performed by a network or component within a mobile network.
A network function is composed of many Network Services; Which have many services such as forwarding packets, monitoring.
What are the main properties of a RESTful protocol? Why do we need it, and how is implemented.
We need REST as it is a basis for communication in 5G Core Control Plane between NF
- Client-Server
- Stateless
- Cacheable
- Layered System
- Uniform Interface
What is a policy framework and does interact with service requirements and control parameters?
What is an exposure framework, and why do we need it?
Very new to 5G; didn’t exist in 4G
- Proxy between network and external applications.
- Authenticates access to services and data
- Hide network internal architecture
- Internally, exposure control can control NF’s directly.
We need the exposure framework for well-defined north-bound API
Describe the main function of AMF
Access and Mobility Management; controls almost everything in terms of access and controlling
Everything behind the AMF, they know nothing about the access networks.
Connection between base station and AMF.
- Registration management
- Security management; all keys are made in AMF
- Connection management; IDLE/Connected
- Reachability management
- Mobility management
- Next Generation Application Protocol (NGAP) signaling
- Selecting AUSF, UDM, PCF, SMF
Examples for interworking with other technologies
Main elements of the RAN
When talking about flexible connectivity models, name the three types of connectivity options and the different data sources it can be connected to.
- Centralised (Internet)
- Regional (e.g. smart city)
- Localised (e.g. video streaming)
- Different data networks
- Different access networks
- Different access points.
Describe how the service based architecture is implemented
It’s class-based.
Name the principles of service-based framework.
- Flexible and dynamic interconnection of NFs; i.e. on the cloud
- NF services offer common interfaces; API’s.
- Consumers of NF service must be authorised.
- Each NF service is self-contained and reusable with an independent life-cycle management.
- System procedures are described by series of service invocations.
Explain the different between:
- Request - Response
- Subscribe - Notify
- Request - Response
- 1:1 communications between consumer and producer
- Response expected within timeframe.
- Subscribe - Notify
- 1:N communications between produce and consumers
Describe the main function of SMF
From Lecture:
- Session Management Function; the main function to manage PDU sessions.
- PDU sessions is a data transport connection from UE to UPF. It establishes it, it deletes it.
- Declares PDU session mode.
- Switch UPF -> switch IP’s; Problem as there is no IP mobility in the network.
- Gateway address given by address.
- Direct interface to the UPF, to handle the PDU sessions and inform UE about PDU establishment and is done through AMF.
- Don’t know what access network is maintained; 4G, 5G. Only AMF knows.
- IP allocation is done by SMF.
Lecture Notes:
GTP-U Tunnel Management; For routing in network including QoS information.
Tunnel Endpoint Identifier; establish a tunnel between AN and Data Network. Must identify where the packet belong to and that what TEID does. One to one mapping in PDU session.
Downlink Notification Management; Mpbile terminal is connected, but IDLE. User plane function doesn’t have mapping between incoming packets and PDU session where packets must be transported. No tunnel; trigger to SMF and then trigger a paging.
Selection of UPF, PCF upon PDU Session Establishment.
Request subscription information from UDM during PDU Session Setup
Supports interfacing with network charging system.
Describe the main function of UPF
Explain the connection management of AMF
- AMF sets up N1 connection over N2 towards a UE to perform control plane signaling and transport NAS messages to the UE.
- All NF can send NAS signaling to UE with the help of AMF
- Moves UE from CM-IDLE to CM-CONNECTED
- This control plane signaling is essential to set up a PDU Session towards SMF (which is also selected by AMF)
