**2. WCDMA QoS architecture**

QoS standardization in UMTS PS domain enables UMTS to provide data service with end-to-end QoS guarantees. 3GPP proposed a layered architecture for supporting end-to-end QoS. It includes the following key elements (Sudhir Dixit et al., 2001):


<sup>1</sup> Wideband Code Division Multiple Access W-CDMA - the radio technology of UMTS - is a part of the ITU IMT-2000 family of 3G Standards.

The Core Network Bearer Service of the UMTS core network connects the UMTS CN Iu Edge Node with the CN Gateway to the external network. The role of this service is to efficiently control and utilise the backbone network in order to provide the contracted UMTS bearer service. The UMTS packet core network shall support different backbone bearer services for variety of QoS. And the UMTS bearer service is realized by a GPRS service in the PS domain

End to End Quality of Service in UMTS Systems 101

The Radio Access Bearer Service is realised by a Radio Bearer Service and an Iu-Bearer Service. The role of the Radio Bearer Service is to cover all the aspects of the radio interface transport. This bearer service uses the UTRA FDD/TDD, which is not elaborated further in this chapter. The Iu-Bearer Service together with the Physical Bearer Service provides the transport between UTRAN and CN. Iu bearer services for packet traffic shall provide different bearer

The Core Network Bearer Service uses a generic Backbone Network Service. The Backbone Network Service covers the layer 1/Layer2 functionality and is selected according to operator's choice in order to fulfill the QoS requirements of the Core Network Bearer Service. The Backbone Network Service is not specific to UMTS but may reuse an existing standard.

The layered UMTS QoS architecture requires the definition of QoS attributes for each bearer service. When defining the UMTS QoS classes, the restrictions and limitations of the radio interface have to be taken into account. The QoS mechanism should be simpler than that in wired network due to different error characteristics of the air interface. Table 1 illustrates the

The main distinguishing factor between these QoS classes is how delay sensitive the traffic is.

The transfer time of real time conversation scheme shall be low because of the conversational nature of the scheme and at the same time that the time relation (variation) between information entities of the stream shall be preserved in the same way as for real time streams. The maximum transfer delay is given by the human perception of video and audio conversation. Therefore the limit for acceptable transfer delay is very strict, as failure to provide low enough transfer delay will result in unacceptable lack of quality. The transfer delay requirement is therefore both significantly lower and more stringent than the round trip delay of the interactive traffic case. The fundamental characteristic for QoS is to preserve time relation (variation) between information entities of stream and

The most well known use of this scheme is telephony speech (e.g. GSM). But with Internet and multimedia a number of new applications will require this scheme, for example voice over IP and video conferencing tools. Real time conversation is always performed between

conversational pattern (stringent and low delay) (3GPP23107, 2011).

or a speech/data service in the CS domain.

services for variety of QoS.

**2.2 QoS requirement 2.2.1 UMTS QoS classes**

QoS classes defined by 3GPP.

**Conversational class**

**2.1.2 The backbone network service**

**2.1.1 The radio bearer service and Iu bearer service**

The layered UMTS QoS architecture is shown in Figure 1. The UMTS network can provide end-to-end QoS services from a Terminal Equipment (TE) to another TE. A network bearer service describes how to realize a certain network QoS. It is defined by the control signaling, user traffic transport and QoS management functionality, which enabling the provision of a contracted QoS (Sudhir Dixit et al., 2001; 3GPP23107, 2011). As the end-to-end service is conveyed over several networks, the end-to-end bearer service consists of different network bearer services. The end-to-end bearer service can be decomposed into TE/MT local bearer service, the UMTS bearer service and the external bearer service.

Fig. 1. UMTS QoS architecture

The TE/MT local bearer service provides communication between the TE and MT parts. MT (Mobil Terminal) provides connection to the UTRAN with basic functions, such as radio attachment to 3G network, authenticating the CS/PS domain, mobility management, etc. TE support call control, authenticating the IMS subscription, etc.

The external bearer service deals with the interoperability and interworking aspects with external IP bearer, and provides the appropriate functionality to support it. It is logical located in the GGSN, which is the gateway of UMTS to external network (Sotiris et al., 2002).

UMTS bearer service provides service by using the radio access bearer service (RAB) and the core network bearer service. The detail is given in the following.

#### **2.1 UMTS bear service**

The UMTS QoS is provided by the UMTS bearer service. It includes the radio access bearer service and the core network bearer service. They reflect the optimized way to realize the UMTS Bearer Service over the respective cellular network topology taking into account aspects such as mobility and mobile subscriber profiles.

The Radio Access Bearer Service provides confidential transport of signalling and user data between MT and CN Iu Edge Node with the QoS adequate to the negotiated UMTS Bearer Service or with the default QoS for signalling. This service is based on the characteristics of the radio interface and is maintained for a moving MT.

2 Will-be-set-by-IN-TECH

The layered UMTS QoS architecture is shown in Figure 1. The UMTS network can provide end-to-end QoS services from a Terminal Equipment (TE) to another TE. A network bearer service describes how to realize a certain network QoS. It is defined by the control signaling, user traffic transport and QoS management functionality, which enabling the provision of a contracted QoS (Sudhir Dixit et al., 2001; 3GPP23107, 2011). As the end-to-end service is conveyed over several networks, the end-to-end bearer service consists of different network bearer services. The end-to-end bearer service can be decomposed into TE/MT local bearer

The TE/MT local bearer service provides communication between the TE and MT parts. MT (Mobil Terminal) provides connection to the UTRAN with basic functions, such as radio attachment to 3G network, authenticating the CS/PS domain, mobility management, etc. TE

The external bearer service deals with the interoperability and interworking aspects with external IP bearer, and provides the appropriate functionality to support it. It is logical located

UMTS bearer service provides service by using the radio access bearer service (RAB) and the

The UMTS QoS is provided by the UMTS bearer service. It includes the radio access bearer service and the core network bearer service. They reflect the optimized way to realize the UMTS Bearer Service over the respective cellular network topology taking into account

The Radio Access Bearer Service provides confidential transport of signalling and user data between MT and CN Iu Edge Node with the QoS adequate to the negotiated UMTS Bearer Service or with the default QoS for signalling. This service is based on the characteristics of

in the GGSN, which is the gateway of UMTS to external network (Sotiris et al., 2002).

service, the UMTS bearer service and the external bearer service.

support call control, authenticating the IMS subscription, etc.

core network bearer service. The detail is given in the following.

aspects such as mobility and mobile subscriber profiles.

the radio interface and is maintained for a moving MT.

Fig. 1. UMTS QoS architecture

**2.1 UMTS bear service**

The Core Network Bearer Service of the UMTS core network connects the UMTS CN Iu Edge Node with the CN Gateway to the external network. The role of this service is to efficiently control and utilise the backbone network in order to provide the contracted UMTS bearer service. The UMTS packet core network shall support different backbone bearer services for variety of QoS. And the UMTS bearer service is realized by a GPRS service in the PS domain or a speech/data service in the CS domain.

#### **2.1.1 The radio bearer service and Iu bearer service**

The Radio Access Bearer Service is realised by a Radio Bearer Service and an Iu-Bearer Service. The role of the Radio Bearer Service is to cover all the aspects of the radio interface transport. This bearer service uses the UTRA FDD/TDD, which is not elaborated further in this chapter.

The Iu-Bearer Service together with the Physical Bearer Service provides the transport between UTRAN and CN. Iu bearer services for packet traffic shall provide different bearer services for variety of QoS.

#### **2.1.2 The backbone network service**

The Core Network Bearer Service uses a generic Backbone Network Service. The Backbone Network Service covers the layer 1/Layer2 functionality and is selected according to operator's choice in order to fulfill the QoS requirements of the Core Network Bearer Service. The Backbone Network Service is not specific to UMTS but may reuse an existing standard.

#### **2.2 QoS requirement**

#### **2.2.1 UMTS QoS classes**

The layered UMTS QoS architecture requires the definition of QoS attributes for each bearer service. When defining the UMTS QoS classes, the restrictions and limitations of the radio interface have to be taken into account. The QoS mechanism should be simpler than that in wired network due to different error characteristics of the air interface. Table 1 illustrates the QoS classes defined by 3GPP.

The main distinguishing factor between these QoS classes is how delay sensitive the traffic is.

#### **Conversational class**

The transfer time of real time conversation scheme shall be low because of the conversational nature of the scheme and at the same time that the time relation (variation) between information entities of the stream shall be preserved in the same way as for real time streams. The maximum transfer delay is given by the human perception of video and audio conversation. Therefore the limit for acceptable transfer delay is very strict, as failure to provide low enough transfer delay will result in unacceptable lack of quality. The transfer delay requirement is therefore both significantly lower and more stringent than the round trip delay of the interactive traffic case. The fundamental characteristic for QoS is to preserve time relation (variation) between information entities of stream and conversational pattern (stringent and low delay) (3GPP23107, 2011).

The most well known use of this scheme is telephony speech (e.g. GSM). But with Internet and multimedia a number of new applications will require this scheme, for example voice over IP and video conferencing tools. Real time conversation is always performed between

with the remote equipment are: web browsing, data base retrieval, server access. Examples of machines interaction with remote equipment are: polling for measurement records and

End to End Quality of Service in UMTS Systems 103

Background traffic is one of the classical data communication schemes that on an overall level is characterised by that the destination is not expecting the data within a certain time. The scheme is thus more or less delivery time insensitive. Another characteristic is that the content of the packets shall be transparently transferred (with low bit error rate). The fundamental characteristics for background class QoS are a) destination is not expecting

When the end-user, that typically is a computer, sends and receives data-files in the background, this scheme applies. Examples are background delivery of E-mails, SMS,

UMTS bearer service attributes describe the service provided by the UMTS network to the user of the UMTS bearer service. A set of QoS attributes (QoS profile) specifies this service. At UMTS bearer service establishment or modification different QoS profiles have to be taken

Traffic class is a type of application for which the UMTS bearer service is optimized. By including the traffic class itself as an attribute, UMTS can make assumptions about the

Maximum bit-rate (kbps) is the maximum number of bits delivered to UMTS at a SAP (Service Access Point) within a period of time, divided by the duration of the period. The traffic is conformant with Maximum bit-rate as long as it follows a token bucket algorithm where token rate equals Maximum bit-rate and bucket size equals Maximum SDU size.

The algorithm is well known as "Token Bucket Algorithm" which has been described in IETF. It is a reference algorithm for the conformance definition of bitrate. This may be used for traffic contract between UMTS bearers and external network/user equipment. In the algorithm, "tokens" represents the allowed data volume, for example in byte. "Tokens" are given at a constant "token rate" by a traffic contract, are stored temporarily in a "token bucket", and are consumed by accepting the packet. This algorithm uses the following two parameters (r and

• r: token rate, (corresponds to the monitored Maximum bitrate/Guaranteed bitrate).

According to a token bucket, conformance can be defined as: "Data is conformant if the amount of data submitted during any arbitrarily chosen time period T does not exceed

• b: bucket size, (the upper bound of TBC, corresponds to bounded burst size). • TBC (Token bucket counter): the number of given/remained tokens at any time.

automatic data base enquiries (tele-machines).

**2.2.2 UMTS bearer service attributes**

the data within a certain time; b) preserve payload content.

download of databases and reception of measurement records.

**Traffic class ('conversational', 'streaming', 'interactive', 'background')**

traffic source and optimise the transport for that traffic type.

b) for the traffic contract and one variable (TBC) for the internal usage.

**Background class**

into account.

(b+rT)".

**Maximum bit-rate (kbps)**


#### Table 1. UMTS QoS classes

peers (or groups) of live (human) end-users. This is the only scheme where the required characteristics are strictly given by human perception.

#### **Streaming class**

Streaming class is characterised by that the time relations (variation) between information entities (i.e. samples, packets) within a flow shall be preserved, although it does not have any requirement on low transfer delay (3GPP23107, 2011). This scheme is one of the newcomers in data communication, raising a number of new requirements in both telecommunication and data communication systems. It is a one-way transport. A user can use this class to watch (listen to) real time video (audio).

The delay variation of the end-to-end flow shall be limited, to preserve the time relation (variation) between information entities of the stream. But as the stream normally is time aligned at the receiving end (in the user equipment), the highest acceptable delay variation over the transmission media is given by the capability of the time alignment function of the application. Acceptable delay variation is thus much greater than the delay variation given by the limits of human perception. The fundamental characteristics for streaming class QoS is to preserve time relation (variation) between information entities of the stream.

#### **Interactive class**

Interactive traffic is the other classical data communication scheme that on an overall level is characterized by the request response pattern of the end-user. At the message destination there is an entity expecting the message (response) within a certain time. Round trip delay time is therefore one of the key attributes. Another characteristic is that the content of the packets shall be transparently transferred (with low bit error rate). The fundamental characteristics for interactive class QoS is to request response pattern, preserve payload content.

This class is applied when an end-user (either a machine or a human) is using on line requesting data from remote equipment (e.g. a server). Examples of human interaction with the remote equipment are: web browsing, data base retrieval, server access. Examples of machines interaction with remote equipment are: polling for measurement records and automatic data base enquiries (tele-machines).

#### **Background class**

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Streaming class


streaming RT

Interactive class Interactive best effort


Web browsing Background Background best effort


expecting the data within a certain time - Preserve payload content

background download of emails

Traffic class Conversational class

RT

Fundamental characteristics

Example of

application

Table 1. UMTS QoS classes

the

**Streaming class**

**Interactive class**

content.

conversational


Conversational pattern (stringent and low delay )

characteristics are strictly given by human perception.

can use this class to watch (listen to) real time video (audio).

voice streaming

video

peers (or groups) of live (human) end-users. This is the only scheme where the required

Streaming class is characterised by that the time relations (variation) between information entities (i.e. samples, packets) within a flow shall be preserved, although it does not have any requirement on low transfer delay (3GPP23107, 2011). This scheme is one of the newcomers in data communication, raising a number of new requirements in both telecommunication and data communication systems. It is a one-way transport. A user

The delay variation of the end-to-end flow shall be limited, to preserve the time relation (variation) between information entities of the stream. But as the stream normally is time aligned at the receiving end (in the user equipment), the highest acceptable delay variation over the transmission media is given by the capability of the time alignment function of the application. Acceptable delay variation is thus much greater than the delay variation given by the limits of human perception. The fundamental characteristics for streaming class QoS is to preserve time relation (variation) between information entities of the stream.

Interactive traffic is the other classical data communication scheme that on an overall level is characterized by the request response pattern of the end-user. At the message destination there is an entity expecting the message (response) within a certain time. Round trip delay time is therefore one of the key attributes. Another characteristic is that the content of the packets shall be transparently transferred (with low bit error rate). The fundamental characteristics for interactive class QoS is to request response pattern, preserve payload

This class is applied when an end-user (either a machine or a human) is using on line requesting data from remote equipment (e.g. a server). Examples of human interaction Background traffic is one of the classical data communication schemes that on an overall level is characterised by that the destination is not expecting the data within a certain time. The scheme is thus more or less delivery time insensitive. Another characteristic is that the content of the packets shall be transparently transferred (with low bit error rate). The fundamental characteristics for background class QoS are a) destination is not expecting the data within a certain time; b) preserve payload content.

When the end-user, that typically is a computer, sends and receives data-files in the background, this scheme applies. Examples are background delivery of E-mails, SMS, download of databases and reception of measurement records.

#### **2.2.2 UMTS bearer service attributes**

UMTS bearer service attributes describe the service provided by the UMTS network to the user of the UMTS bearer service. A set of QoS attributes (QoS profile) specifies this service. At UMTS bearer service establishment or modification different QoS profiles have to be taken into account.

#### **Traffic class ('conversational', 'streaming', 'interactive', 'background')**

Traffic class is a type of application for which the UMTS bearer service is optimized. By including the traffic class itself as an attribute, UMTS can make assumptions about the traffic source and optimise the transport for that traffic type.

#### **Maximum bit-rate (kbps)**

Maximum bit-rate (kbps) is the maximum number of bits delivered to UMTS at a SAP (Service Access Point) within a period of time, divided by the duration of the period. The traffic is conformant with Maximum bit-rate as long as it follows a token bucket algorithm where token rate equals Maximum bit-rate and bucket size equals Maximum SDU size.

The algorithm is well known as "Token Bucket Algorithm" which has been described in IETF. It is a reference algorithm for the conformance definition of bitrate. This may be used for traffic contract between UMTS bearers and external network/user equipment. In the algorithm, "tokens" represents the allowed data volume, for example in byte. "Tokens" are given at a constant "token rate" by a traffic contract, are stored temporarily in a "token bucket", and are consumed by accepting the packet. This algorithm uses the following two parameters (r and b) for the traffic contract and one variable (TBC) for the internal usage.


According to a token bucket, conformance can be defined as: "Data is conformant if the amount of data submitted during any arbitrarily chosen time period T does not exceed (b+rT)".

out-of-sequence SDUs are acceptable or not. Whether out-of-sequence SDUs are dropped

End to End Quality of Service in UMTS Systems 105

Maximum SDU size (octets) means the maximum allowed SDU size. The maximum SDU

SDU format information (bits) is a list of possible exact sizes of SDUs. UTRAN needs SDU size information to operate in transparent RLC protocol mode, which is beneficial to spectral efficiency and delay when RLC re-transmission is not used. Thus, if the

SDU error ratio indicates the fraction of SDUs lost or detected as erroneous. SDU error ratio is defined only for conforming traffic. It is used to configure the protocols, algorithms

**Residual bit error ratio** Residual bit error ratio indicates the undetected bit error ratio in the delivered SDUs. If no error detection is requested, Residual bit error ratio indicates the bit error ratio in the delivered SDUs. It is used to configure radio interface protocols,

Delivery of erroneous SDU (yes/no/-) indicates whether SDUs detected as erroneous shall be delivered or discarded. 'Yes' implies that error detection is employed and that erroneous SDUs are delivered together with an error indication, 'no' implies that error detection is employed and that erroneous SDUs are discarded, and '-' implies that SDUs are delivered without considering error detection. It is used to decide whether error detection is needed

Transfer delay (ms) indicates maximum delay for 95th percentile of the distribution of delay for all delivered SDUs during the lifetime of a bearer service, where delay for an SDU is defined as the time from a request to transfer an SDU at one SAP to its delivery at the other SAP. Transfer delay can be used to specify the delay tolerated by the application.

Traffic handling priority specifies the relative importance for handling of all SDUs belonging to the UMTS bearer compared to the SDUs of other bearers. Within the interactive class, there is a definite need to differentiate between bearer qualities. This is handled by using the traffic handling priority attribute, to allow UMTS to schedule traffic accordingly. By definition, priority is an alternative to absolute guarantees, and thus these

Allocation/Retention priority specifies the relative importance compared to other UMTS bearers for allocation and retention of the UMTS bearer. The Allocation/Retention

or re-ordered depends on the specified reliability.

size is used for admission control and policing.

application can specify SDU sizes, the bearer is less expensive.

and whether frames with detected errors shall be forwarded or not.

It allows UTRAN to set transport formats and ARQ parameters.

two attribute types cannot be used together for a single bearer.

and error detection schemes, primarily within UTRAN.

algorithms and error detection coding.

**Delivery of erroneous SDUs (y/n/-)**

**Maximum SDU size (octets)**

**SDU format information (bits)**

**SDU error ratio**

**Transfer delay (ms)**

**Traffic handling priority**

**Allocation/Retention priority**

Fig. 2. Operation example of the reference conformance algorithm

The algorithm is described here (Figure 2, (3GPP23107, 2011)). Token bucket counter (TBC) is usually increased by "r" in each small time unit. However, TBC has upper bound "b" and the value of TBC shall never exceed "b". When a packet i with length Li arrives, the receiver checks the current TBC. If the TBC value is equal to or larger than Li, the packet arrival is judged compliant, i.e., the traffic is conformant. At this moment tokens corresponding to the packet length is consumed, and TBC value decreases by Li. When a packet j with length Lj arrives, if TBC is less than Lj, the packet arrival is non-compliant, i.e., the traffic is not conformant. In this case, the value of TBC is not updated.

The Maximum bitrate is the upper limit a user or application can accept or provide. All UMTS bearer service attributes may be fulfilled for traffic up to the Maximum bitrate depending on the network conditions. The downlink of the radio interface can use maximum bitrate to make code reservations. Its purpose is:


#### **Guaranteed bitrate (kbps)**

Guaranteed bitrate (kbps) is defined as: a guaranteed number of bits delivered by UMTS at a SAP within a period of time (provided that there is data to deliver), divided by the duration of the period. The traffic is conformant with the guaranteed bitrate as long as it follows a token bucket algorithm where token rate equals Guaranteed bitrate and bucket size equals Maximum SDU size.

UMTS bearer service attributes, e.g. delay and reliability attributes, are guaranteed for traffic up to the Guaranteed bitrate. For the traffic exceeding the Guaranteed bitrate the UMTS bearer service attributes are not guaranteed. Guaranteed bitrate may be used to facilitate admission control based on available resources, and for resource allocation within UMTS.

#### **Delivery order (y/n)**

Delivery order indicates whether the UMTS bearer shall provide in-sequence SDU delivery or not. This attribute is derived from the user protocol (PDP type) and specifies if out-of-sequence SDUs are acceptable or not. Whether out-of-sequence SDUs are dropped or re-ordered depends on the specified reliability.

#### **Maximum SDU size (octets)**

Maximum SDU size (octets) means the maximum allowed SDU size. The maximum SDU size is used for admission control and policing.

#### **SDU format information (bits)**

SDU format information (bits) is a list of possible exact sizes of SDUs. UTRAN needs SDU size information to operate in transparent RLC protocol mode, which is beneficial to spectral efficiency and delay when RLC re-transmission is not used. Thus, if the application can specify SDU sizes, the bearer is less expensive.

#### **SDU error ratio**

6 Will-be-set-by-IN-TECH

The algorithm is described here (Figure 2, (3GPP23107, 2011)). Token bucket counter (TBC) is usually increased by "r" in each small time unit. However, TBC has upper bound "b" and the value of TBC shall never exceed "b". When a packet i with length Li arrives, the receiver checks the current TBC. If the TBC value is equal to or larger than Li, the packet arrival is judged compliant, i.e., the traffic is conformant. At this moment tokens corresponding to the packet length is consumed, and TBC value decreases by Li. When a packet j with length Lj arrives, if TBC is less than Lj, the packet arrival is non-compliant, i.e., the traffic is not

The Maximum bitrate is the upper limit a user or application can accept or provide. All UMTS bearer service attributes may be fulfilled for traffic up to the Maximum bitrate depending on the network conditions. The downlink of the radio interface can use maximum bitrate to make

1. to limit the delivered bitrate to applications or external networks with such limitations; 2. to allow maximum wanted user bitrate to be defined for applications able to operate with

Guaranteed bitrate (kbps) is defined as: a guaranteed number of bits delivered by UMTS at a SAP within a period of time (provided that there is data to deliver), divided by the duration of the period. The traffic is conformant with the guaranteed bitrate as long as it follows a token bucket algorithm where token rate equals Guaranteed bitrate and bucket

UMTS bearer service attributes, e.g. delay and reliability attributes, are guaranteed for traffic up to the Guaranteed bitrate. For the traffic exceeding the Guaranteed bitrate the UMTS bearer service attributes are not guaranteed. Guaranteed bitrate may be used to facilitate admission control based on available resources, and for resource allocation within

Delivery order indicates whether the UMTS bearer shall provide in-sequence SDU delivery or not. This attribute is derived from the user protocol (PDP type) and specifies if

Fig. 2. Operation example of the reference conformance algorithm

conformant. In this case, the value of TBC is not updated.

different rates (e.g. applications with adapting codecs).

code reservations. Its purpose is:

**Guaranteed bitrate (kbps)**

UMTS.

**Delivery order (y/n)**

size equals Maximum SDU size.

SDU error ratio indicates the fraction of SDUs lost or detected as erroneous. SDU error ratio is defined only for conforming traffic. It is used to configure the protocols, algorithms and error detection schemes, primarily within UTRAN.

**Residual bit error ratio** Residual bit error ratio indicates the undetected bit error ratio in the delivered SDUs. If no error detection is requested, Residual bit error ratio indicates the bit error ratio in the delivered SDUs. It is used to configure radio interface protocols, algorithms and error detection coding.

#### **Delivery of erroneous SDUs (y/n/-)**

Delivery of erroneous SDU (yes/no/-) indicates whether SDUs detected as erroneous shall be delivered or discarded. 'Yes' implies that error detection is employed and that erroneous SDUs are delivered together with an error indication, 'no' implies that error detection is employed and that erroneous SDUs are discarded, and '-' implies that SDUs are delivered without considering error detection. It is used to decide whether error detection is needed and whether frames with detected errors shall be forwarded or not.

#### **Transfer delay (ms)**

Transfer delay (ms) indicates maximum delay for 95th percentile of the distribution of delay for all delivered SDUs during the lifetime of a bearer service, where delay for an SDU is defined as the time from a request to transfer an SDU at one SAP to its delivery at the other SAP. Transfer delay can be used to specify the delay tolerated by the application. It allows UTRAN to set transport formats and ARQ parameters.

#### **Traffic handling priority**

Traffic handling priority specifies the relative importance for handling of all SDUs belonging to the UMTS bearer compared to the SDUs of other bearers. Within the interactive class, there is a definite need to differentiate between bearer qualities. This is handled by using the traffic handling priority attribute, to allow UMTS to schedule traffic accordingly. By definition, priority is an alternative to absolute guarantees, and thus these two attribute types cannot be used together for a single bearer.

#### **Allocation/Retention priority**

Allocation/Retention priority specifies the relative importance compared to other UMTS bearers for allocation and retention of the UMTS bearer. The Allocation/Retention

Fig. 3. QoS management function for UMTS bearer service in the control plane

provide service to upper layer service manager.

established by the UMTS BS control functions.

QoS at the transfer. It is located at UTRAN, Gateway.

according to the QoS requirement of each user data unit.

**2.3.2 QoS management in user plane**

Service manager co-ordinates the related functions in control plane to establish, modify and maintain the service. All user plane QoS management functions are supported by service manager with the relevant attributes. The service manager may perform an attribute translation to request lower layer services. Service manager at UMTS bearer service level is located at MT, CN EDGE and Gateway. The UMTS BS manager can signal among each other and via the translation function with external instances to establish / modify a UMTS bearer service. The UMTS BS manager will interrogate with its associated admission / capability control whether the network entity supports a specific requested service and whether the required resource is available. The UMTS BS manager at CN EDGE also has to verify with the subscription control the administrative rights for using the service. Based on the layered UMTS QoS architecture, UMTS bearer service manager will translate the UMTS bearer service attributes into attributes of the lower layer service manager. For example, the UMTS BS manager of the CN EDGE will translate the UMTS bearer service attributes into RAB service attributes, Iu bearer service attributes, and CN bearer service attributes. Each low layer will

End to End Quality of Service in UMTS Systems 107

The Figure 4 shows the QoS management functions of UMTS bearer service in the user plane. They are mapping function, classification function, resource manager and traffic conditioner. They are used to maintain the data transfer characteristics according to the commitments

Mapping function provides each data with the specific marking for receiving the requested

Classification function (Class.) in the MT and Gateway assigns user data units received from the external bearer service or the local bearer service to the appropriate UMTS bearer service

Traffic conditioner provides conformance between the negotiated QoS for a service nad the data unit traffic. Policing or traffic shaping is used for traffic conditioning. The policing function compares the data unit traffic with the related QoS attributes. Data units not matching the relevant attributes will be dropped or marked as not matching, for preferential

Priority attribute is a subscription attribute which is not negotiated from the mobile terminal. Priority is used for differentiating between bearers when performing allocation and retention of a bearer. Where there is no enough resource, the relevant network elements can use the Allocation/Retention Priority to prioritize bearers with a high Allocation/Retention Priority over bearers with a low Allocation/Retention Priority when performing admission control.

#### **Source statistics descriptor ('speech'/'unknown')**

Source statistics descriptor ('speech'/'unknow') specifies characteristics of the source of submitted SDUs. Conversational speech has a well-known statistical behaviour (or the discontinuous transmission (DTX) factor). By using source statistics descriptor, a network element can know whether the SDUs of a UMTS bearer generated by a speech source or not. UTRAN, the SGSN and the GGSN and also the UE may, based on experience, calculate a statistical multiplex gain for use in admission control on the relevant interfaces.

#### **2.3 QoS management for UMTS bearer service**

In the section, an overview of QoS functions is described which is used to establish, modify, and maintain a UMTS bearer service with a specific QoS. The allocation of these functions to the UMTS entities indicates the requirement for specific entity to enforce the QoS commitments negotiated for the UMTS bearer service. UMTS is split into user plane and control plane for easy expanding in the future. So QoS management functions are also split into user plane and control plane. All of the QoS management functions in both planes (control and user plane) will ensure the provision of the negotiated service between the access points of the UMTS bearer service. The end-to-end service is provided by translation/mapping with UMTS external services.

#### **2.3.1 QoS management in control plane**

The QoS management functions in control plane are shown in Figure 3. The QoS functions for UMTS bearer service include service manager, translation function, admission/capability control and subscription control in the control plane. These functions are used to establish and modify a UMTS bearer service through signaling/negotiating with UMTS external services, establishing/modifying UMTS internal services.

Subscription control checks the administrative rights when an UMTS bearer service user requires a service with the specified QoS. It is located at CN EDGE.

Admission capability control will maintains available resource information of a network entity, and resource allocated to UTMS bearer service. When receiving an UMTS bearer service request or modification request, admission / capability control function determines whether the required resources can be provided or not. If the network can provide resources, it will reserve these resources. This function also checks the capability of a network entity, i.e. whether the specific service is implemented and not blocked for administrative reasons. It is located at MT, UTRAN, CN EDGE and Gateway.

Translation function is used to convert between internal service primitives and external protocols. It is located at MT and Gateway. At MT and Gateway, translation function converts between UMTS bearer service attributes and external network QoS attributes.

8 Will-be-set-by-IN-TECH

performing admission control.

**Source statistics descriptor ('speech'/'unknown')**

**2.3 QoS management for UMTS bearer service**

by translation/mapping with UMTS external services.

**2.3.1 QoS management in control plane**

establishing/modifying UMTS internal services.

located at MT, UTRAN, CN EDGE and Gateway.

requires a service with the specified QoS. It is located at CN EDGE.

Priority attribute is a subscription attribute which is not negotiated from the mobile terminal. Priority is used for differentiating between bearers when performing allocation and retention of a bearer. Where there is no enough resource, the relevant network elements can use the Allocation/Retention Priority to prioritize bearers with a high Allocation/Retention Priority over bearers with a low Allocation/Retention Priority when

Source statistics descriptor ('speech'/'unknow') specifies characteristics of the source of submitted SDUs. Conversational speech has a well-known statistical behaviour (or the discontinuous transmission (DTX) factor). By using source statistics descriptor, a network element can know whether the SDUs of a UMTS bearer generated by a speech source or not. UTRAN, the SGSN and the GGSN and also the UE may, based on experience, calculate

a statistical multiplex gain for use in admission control on the relevant interfaces.

In the section, an overview of QoS functions is described which is used to establish, modify, and maintain a UMTS bearer service with a specific QoS. The allocation of these functions to the UMTS entities indicates the requirement for specific entity to enforce the QoS commitments negotiated for the UMTS bearer service. UMTS is split into user plane and control plane for easy expanding in the future. So QoS management functions are also split into user plane and control plane. All of the QoS management functions in both planes (control and user plane) will ensure the provision of the negotiated service between the access points of the UMTS bearer service. The end-to-end service is provided

The QoS management functions in control plane are shown in Figure 3. The QoS functions for UMTS bearer service include service manager, translation function, admission/capability control and subscription control in the control plane. These functions are used to establish and modify a UMTS bearer service through signaling/negotiating with UMTS external services,

Subscription control checks the administrative rights when an UMTS bearer service user

Admission capability control will maintains available resource information of a network entity, and resource allocated to UTMS bearer service. When receiving an UMTS bearer service request or modification request, admission / capability control function determines whether the required resources can be provided or not. If the network can provide resources, it will reserve these resources. This function also checks the capability of a network entity, i.e. whether the specific service is implemented and not blocked for administrative reasons. It is

Translation function is used to convert between internal service primitives and external protocols. It is located at MT and Gateway. At MT and Gateway, translation function converts

between UMTS bearer service attributes and external network QoS attributes.

Fig. 3. QoS management function for UMTS bearer service in the control plane

Service manager co-ordinates the related functions in control plane to establish, modify and maintain the service. All user plane QoS management functions are supported by service manager with the relevant attributes. The service manager may perform an attribute translation to request lower layer services. Service manager at UMTS bearer service level is located at MT, CN EDGE and Gateway. The UMTS BS manager can signal among each other and via the translation function with external instances to establish / modify a UMTS bearer service. The UMTS BS manager will interrogate with its associated admission / capability control whether the network entity supports a specific requested service and whether the required resource is available. The UMTS BS manager at CN EDGE also has to verify with the subscription control the administrative rights for using the service. Based on the layered UMTS QoS architecture, UMTS bearer service manager will translate the UMTS bearer service attributes into attributes of the lower layer service manager. For example, the UMTS BS manager of the CN EDGE will translate the UMTS bearer service attributes into RAB service attributes, Iu bearer service attributes, and CN bearer service attributes. Each low layer will provide service to upper layer service manager.

#### **2.3.2 QoS management in user plane**

The Figure 4 shows the QoS management functions of UMTS bearer service in the user plane. They are mapping function, classification function, resource manager and traffic conditioner. They are used to maintain the data transfer characteristics according to the commitments established by the UMTS BS control functions.

Mapping function provides each data with the specific marking for receiving the requested QoS at the transfer. It is located at UTRAN, Gateway.

Classification function (Class.) in the MT and Gateway assigns user data units received from the external bearer service or the local bearer service to the appropriate UMTS bearer service according to the QoS requirement of each user data unit.

Traffic conditioner provides conformance between the negotiated QoS for a service nad the data unit traffic. Policing or traffic shaping is used for traffic conditioning. The policing function compares the data unit traffic with the related QoS attributes. Data units not matching the relevant attributes will be dropped or marked as not matching, for preferential

to be mapped specifically for the interfaces to the UTRAN, GMSC-Server and CS-MGW. To provide QoS the CS-MGW has to perform admission control for the bearer resource which is therefore a part of the call admission control. Additionally, the CS-MGW is responsible for the

End to End Quality of Service in UMTS Systems 109

With the separation of transport and control in the CS domain the resource allocation becomes more flexible. The new transport techniques ATM and IP (which are available for the CS bearer independent domain) allow a more efficient network usage from a parallel transmission of voice and data possibly leading to the consolidation of the whole PLMN (including the PS domain and parts of RAN) on one transport network. The QoS issue in the CS domain with IP or ATM based transport is to guarantee the same QoS as a TDM based

Since the PS domain provides packet data services, which are characterized by individual transmission of packets. QoS of different packet service is defined by a set of explicitly defined QoS parameters. So some effort is necessary to assure that packets of one flow are transmitted

The 3GPP specificationscitep (3GPP23107, 2011) define the QoS management functions in the UMTS bearer service for both control plane and user plane. Establishment of QoS within a UMTS network is achieved through the Packet Data Protocol (PDP) context activation procedure. The user equipment (UE) sends an Active PDP Context Request message to the SGSN, which contains the desired QoS profile, among other parameters. With these QoS attributes the treatment of the packets is sufficiently defined and all packets (or flows) belonging to the same PDP context are handled in the same way by the GPRS bearer service. After the UE sends a PDP context request with explicitly defined QoS parameters, the SGSN will negotiate the QoS parameters which includes subscription check and admission control (capability and resource check). Then the SGSN interacts with the UTRAN and the GGSN to establish the PDP context. The GGSN also performs admission control, i.e. the resource check for the GPRS as well as for the external bearer service. Additionally, the GGSN has to map

IP multimedia subsystem (IMS) is introduced in 3GPP Release 5. It is an IP based system overlay on the PS domain. It support Session Initiation Protocol (SIP) based multimedia service. IMS can support end-to-end IP QoS service by using IP based bearer service. The IP based bearer service is supported by MS local bearer service, UMTS bearer service and

Since 3GPP Release 5, the UMTS will support QoS in the IP layer between UE and multimedia application server/UE. The UE and GGSN have important roles in the IP layer QoS framework, they map QoS parameters between IP layer bearer service and UMTS bearer

For supporting IP layer QoS, 3GPP introduces the policy based QoS management in the IMS. The policy framework is recommended for policy management in IETF. The detail discusses

QoS mappings to the Iu-, CN- and external bearer services.

QoS parameters from the GPRS to the external bearer service.

service. The detail will be discussed in the section 3.

**2.4.3 QoS in IP multimedia subsystem**

external service.

is given in the section 4.

PLMN with increased bandwidth efficiency.

**2.4.2 QoS in PS domain**

with guaranteed QoS.

Fig. 4. QoS management function for UMTS bearer service in the user plane

dropping in case of congestion. The traffic shaper forms the data unit traffic according to the QoS of the service. The shaper algorithm is "Token Bucket Algorithm". At MT side, the traffic conditioner (Cond.) provides conformance of the uplink user data traffic with the QoS attributes of the relevant UMTS bearer service. In the Gateway a traffic conditioner may provide conformance of the downlink user data traffic with the QoS attributes of the relevant UMTS bearer service; i.e., on a per PDP context basis. A traffic conditioner in the UTRAN forms this downlink data unit traffic according to the relevant QoS attributes.

Resource Manager distributes the available resources between all services sharing the same resource. The resource manager distributes the resources according to the required QoS. Example means for resource management are scheduling, bandwidth management and power control for the radio bearer. It is located at MT, UTRAN, CN EDGE and Gateway.
