LTE QoS Quality of Service,class identifier(QCI),QoS in LTE

LTE QoS Quality of Service, class identifier(QCI), QoS in LTE

This page describes LTE Quality of Service (QoS) basics, and LTE QoS class identifier (QCI).
It covers LTE QCIs which include QCI-1, QCI-2, QCI-3, QCI-4, QCI-5, QCI-6, QCI-7, QCI-8 and QCI-9 class identifiers.

LTE QoS allows both LTE compliant subscribers and services to be differentiated.
Premium subscribers can be priotized over basic subscribers. Real time services can
be prioritized over non realtime services.

As we know unloaded network will not create any problems to LTE subscribers as per as service provision is concerned.
The real challenge is when network gets congested. This is the time when LTE QoS comes in place.
As the network load will increase, prioritization determines which subscribers and performing well and
which are not performing.

Like other systems, LTE QoS also impacts admission control decisions.
Connections with guaranteed QoS require larger resources.
These connections will be blocked in case of insufficient resources.

Table-1 mentions QoS parameters associated with each LTE bearer type.
QoS is applied between UE and PDN gateway within LTE network.

LTE QoS
GBR
Non-GBR

QoS Class Identifier
Supported
Supported

Allocation and Retention Priority
Supported
Supported

Guaranteed Bit rate
Supported

Maximum Bit rate
Supported

APN Aggregate Maximum Bit rate

Supported

UE Aggregate Maximum Bit rate

Supported

Table-2 below represents relationship between QCI and associated set of QoS characteristics.
3GPP has adopted this to reduce both the signalling requirement and maximum no. of possible
parameter combinations.

LTE QoS Table covering LTE QCI-1 to QCI-9

LTE QCI
Resource Type
Priority
Packet Delay Budget
Packet Error Loss Rate
Example Services
QCI-1
GBR
2
100ms
10-2
Conversational voice

QCI-2
4
150ms
10-3
live streaming of conversational voice
QCI-3
3
50ms
Real time gaming

QCI-4
5
300ms
10-6
Non conversational video(Buffered streaming)

QCI-5
Non-GBR
1
100ms
IMS signalling

QCI-6
6
300ms
Video (buffered streaming),TCP based applications

QCI-7
7
100ms
10-3
Voice, video (live streaming) , interactive gaming

QCI-8
8
300ms
10-6
Video (Buffered streaming) , TCP based applications

QCI-9
9

As mentioned LTE QCI determines which bearers are categorized as GBR and which as non GBR.
The priority associated with each QCI is applied when forwarding packets across the LTE network.
A priority of 1 corresponds to highest one.

Packet delay budget defines upper bound for packet delay between UE and PCEF with PDN gateway.
Average delay between eNodeB and PCEF of 20ms is assumed and rest of the delay budget is
available for RAN.

LTE QCI table-2 mentions packet error loss rate. It is defined as % of higher layer packets which are lost
during periods during when network is not congested.

LTE QoS References: 3GPP TS 36.300, 3GPP TS23.401,3GPP TS23.203

LTE tutorial related links

This tutorial on LTE covers LTE basics and following sub topics on LTE:
Main page 
features 
terminologies 
Frame 
TDD FDD 
Channel types 
PHY 
stack 
throughput 
VoLTE 
CA  
cell search 
network entry 
Timers 
PSS vs SSS 
Security  
LTE Bands 
EARFCN 
Hotspot 
router 

LTE Channels and Signals

LTE PSS SSS
LTE RS DMRS SRS
LTE PUSCH
LTE PUCCH
LTE PRACH
LTE PMCH
LTE PHICH
LTE PDSCH
LTE PDCCH
LTE PCFICH
LTE PBCH

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