UMTS to LTE Flashcards
General Functions of Components?
Core Network
Radio Access Network
UE
Core Network?
Carries traffic from one RAN to another RAN.
Hosts controlling/management servers.
Hosts the network intelligence.
Radio Access Network?
Provides radio access to the user
Connects the user to the core network and services
Implements air interface
User Equipment?
Provides user interface to the user
Implements air interface to connect to the RAN
RNC?
Radio Network Controller
Passes user’s voice information and data packets between the NodeB and CN
In UMTS, sectors are called?
Cells
In GSM the whole area is called?
Cell
Handover?
When a mobile moves from one part of the network to another, it has to stop communicating with one cell and start communicating with the next cell along.
Two different techniques of Handover?
Handover - for mobiles that are actively communicating with the network.
Cell Reselection - for mobiles that are on standby.
Hard Handover?
Break before make.
- Happens when a UE can connect only one BS simultaneously.
Example of Hard Handover?
GSM
Soft Handover?
Make before break
- Happens when UE can connect more than one BS simultaneously.
Example of Soft Handover?
UMTS
Inter-System Handover?
Handover between different systems
Example of Inter-System Handover?
From UMTS to GSM
Media GW?
Processes, routes voice traffic.
Simillar to MSC function in GSM
MSC Server?
Controls the network using signalling.
Setup, manage, teardown connections.
GGSN?
Act as interfaces to outside data network
SGSN?
Route data between the BSs and the GGSN
Handle the signalling messages to set up, manage and tear down the data streams.
HSS?
central database
contains information about all subscribers
PDU?
Protocol Data Unit
- Output data structure of any protocol
- Delivers this data structure to lower layer protocol as payload to that protocol.
SDU?
Service Data Unit
- Payload received from upper layer protocol
- Header is added to this to create PDU of this protocol
Motivations for LTE?
The growth of mobile data
Increasing the System Capacity
Shannon channel capacity formula gives?
The maximum data rate achievable in an AWGN channel.
To increase the System Capacity we need?
Increase the numbers of channels in cell.
Replicate the cells, hence all channels.
Replicate the all available channels within a cell.
EPS?
Evolved Packet System
RAT?
Radio Access Technology
