Side_1_360

Each of the QoS classes in Table 1 are associ-
ated with a set of QoS parameters describing the
requirements demanded from the associated
applications. Table 2 describes the QoS attri-
butes and Table 3 gives the value ranges of
UMTS bearer service attributes for the different
QoS classes. These values give the capabilities
demanded from the UMTS network. Value
ranges for the Radio access bearer have also
been put forward. Some parameters, e.g. transfer
delay, will contain a lower maximum value for

the Radio access due to the delay budget through

the Core network. For asymmetric bearers some

attributes may have different values in uplink

than in downlink direction.

3.5 UMTS Bearer Establishment

To illustrate how the different parts work

together we present the overall procedure for

establishing a UMTS bearer. We also discuss

how QoS is mapped to DiffServ within the IP

transport networks. Additionally we address the

Table 1 UMTS QoS classes

and their characteristics

Table 2 UMTS Bearer

Service attributes

Traffic Conversational Streaming Interactive Background

class class class class class

Conversational streaming RT Interactive Background

Real Time (RT) best effort best effort

Fundamental Preserve time Preserve time Request Destination

characteristics relation relation response is not

(variation) between (variation) pattern expecting

information entities between the data

of the stream information Preserve within a

entities of payload certain time

• Conversational the stream content Preserve


• pattern (stringent payload


• and low delay) content

Example voice streaming web browsing Background

of the video download of

application e-mails

Traffic class UMTS QoS classes like conversational, streaming.

Maximum bitrate (kb/s) Maximum no. of bits provided by the UMTS network within a

period of time.

Guaranteed bitrate Guaranteed number of bits delivered by the UMTS network

within a period of time.

A value of k greater than one Maximum SDU (Service Data

Unit) size may be specified in releases beyond R99 to cap-

ture burstiness of sources.

Deliver order (y/n) In-sequence delivery of SDU packets or not.

Maximum SDU size (octets) The maximum size of SDUs.

SDU format information (bits) List of possible exact sizes of SDU.

SDU error ratio Fraction of SDUs lost or deteced as erroneous.

Residual bit error ratio Undected bit error ratio in the delivered SDUs.

Delivery of erroneous SDUs (y/n) Whether SDUs detected as erroneous shall be delivered or

discarded or not.

Transfer delay (ms) Maximum delay for 95th percentile of the distribution of delay

for all delivered SDUs.

Delay is time from a request to transfer an SDU at one SAP

to its delivery at the other SA.

Traffic handling priority Relative importance for handling of all SDUs belonging to the

UMTS bearer compared to the SDUs of other bearers.

Allocation/retention priority Used for differentiating between bearers when performing

allocation and retention of a bearer.