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layers. An important task is to configure the
mapping the best possible way. Since QoS
parameter mapping and configuration of the QoS
mechanisms may depend on different issues, e.g.
operator strategy, these mappings are not speci-
fied by 3GPP. Also the scheduling mechanism in
the UMTS nodes has not been specified by
3GPP and will be vendor specific. It has been
recognised that it is important for each operator
to be able to configure the QoS parameters with
regard to its own policies of customer behaviour.
This includes how the system will handle situa-
tion such as heavy traffic, congestion, faults, as
well as the actions against misbehaving users
and the impact on pricing rates.

An example of mapping between UMTS classes
and DiffServ code points is given in Table 4.

3.5.3 QoS across the Radio Interface
The Radio Network Controller (RNC) is respon-
sible for the allocation, management and termi-
nation of radio bearers. Radio bearers are estab-
lished when a radio access bearer establishment
is requested. The RNC first determines whether
there are enough resources to service the request
and if not, it may degrade an existing radio
access bearer with lower priority so as to allow
the newcomer. Alternatively, it will reject the
request. When the resources are available the
resource manager selects the appropriate radio
bearer to establish according to the values of the
parameters specified in the RAB establishment
request. A radio bearer is characterised by the
type of channel it is using, the parameters de-
scribing this channel and the configuration of
the radio protocols.

There are two main types of channels, dedicated
channels for time stringent traffic and shared
channels for non time stringent traffic. For a
dedicated channel the access to this channel is
restricted to the owner of the bearer. The channel
is also characterised by the frequency and the
CDMA codes. The code defines the raw data-

rate on the channel. Error coding is always used

and additional redundancy is provided at the

radio link layer control by a retransmission pro-

tocol. The choice of the error coding code and

whether to use retransmissions or not depend on

the level of reliability needed for the radio bearer

and the delay requirements. The mapping algo-

rithm of the QoS given in the radio access bearer

Table 4 QoS class mapping

between UMTS QoS and Diff-

Serv Code point

Figure 3-6 Radio Bearer

establishment

UMTS QoS class DiffServ class

Conversational Expedited forwarding

Streaming Assured forwarding (AF11, AF12, AF13)

Interactive priority 1 Assured forwarding (AF21, AF22, AF23)

Interactive priority 2 Assured forwarding (AF31, AF32, AF33)

Interactive priority 3 Assured forwarding (AF41, AF42, AF43)

Background Best effort

Reconfiguration or

release of other bearers

Configuration and set

up the radio bearer

Yes but...

No

problem

RAB Set-

Up request

QoS

Magic Box

Admission Control

+ Resource

Allocation

Wait in the queue

No way

RAB Reject (cause) RAB Reject (cause)

Configure and

set up the radio

bearer

QoS Transport Channel Type of service Radio protocols

Conversational Dedicated uplink Low delay, No retransmissions

8 kb/s guaranteed and downlink, high priority, (RLC transparent)

bit rate 8 kb/s low reliability

Streaming Dedicated downlink Guaranteed delay, No retransmissions

64 kb/s video 64 kb/s and packet high priority, (RLC transparent)

channel uplink low reliability

Interactive mean Shared channel Mean data rate Retransmissions

bit rate 64 kb/s uplink 16 kb/s guaranteed,

on downlink and downlink high reliability

144 kb/s

Table 5 Mapping of QoS to

Radio Bearer