**2.4 QoS management in UMTS**

### **2.4.1 QoS in CS domain**

CS call control will control the QoS in the CS domain. MSC server and CS-MGW will provide QoS related functions. For UMTS release '99 CS-CC, the QoS related bearer definitions of GSM (as defined in bearer capability information element, octet 6 and its extensions) are sufficient.

In the CS domain the UE can only request a certain service with a well defined set of QoS parameters. CS domain uses traditional "circuit switching" technology, i.e. a constant set of resources exclusively dedicated to a connection. All CS domain services will require real-time bearers but differ in bandwidth and delay requirements. Based on the Bearer Capability information element the following services can be identified:


According to the standard, speech as well as the transparent data service is mapped to the conversational class while the non-transparent data service is mapped to the streaming class.

The MSC-Server is responsible for the service negotiation which includes subscription check and admission control. Furthermore, the QoS parameters corresponding to the service have 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 QoS mappings to the Iu-, CN- and external bearer services.

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 PLMN with increased bandwidth efficiency.

### **2.4.2 QoS in PS domain**

10 Will-be-set-by-IN-TECH

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

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.

CS call control will control the QoS in the CS domain. MSC server and CS-MGW will provide QoS related functions. For UMTS release '99 CS-CC, the QoS related bearer definitions of GSM (as defined in bearer capability information element, octet 6 and its extensions) are sufficient. In the CS domain the UE can only request a certain service with a well defined set of QoS parameters. CS domain uses traditional "circuit switching" technology, i.e. a constant set of resources exclusively dedicated to a connection. All CS domain services will require real-time bearers but differ in bandwidth and delay requirements. Based on the Bearer Capability

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

forms this downlink data unit traffic according to the relevant QoS attributes.

information element the following services can be identified:

3. data, transparent: from the ITC and CE parameters.

1. speech: from the Information Transfer Capability (ITC) parameter;

2. data, non-transparent: from the ITC and Connection element (CE) parameters;

According to the standard, speech as well as the transparent data service is mapped to the conversational class while the non-transparent data service is mapped to the streaming class. The MSC-Server is responsible for the service negotiation which includes subscription check and admission control. Furthermore, the QoS parameters corresponding to the service have

**2.4 QoS management in UMTS**

**2.4.1 QoS in CS domain**

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 with guaranteed QoS.

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 QoS parameters from the GPRS to the external bearer service.

#### **2.4.3 QoS in IP multimedia subsystem**

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 external service.

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

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 is given in the section 4.

Generally, we can see that there are two methods to support QoS in IP network. One is IntServ (Integrated Service), the other is DiffServ (Differentiated Service). IneServ is Per Flow based QoS control mechanism. Diffserv is Per Aggregate based QoS control mechanism. To accommodate the need for these two types of QoS, there are following QoS protocols and

End to End Quality of Service in UMTS Systems 111

The Internet integrated services (IntServ) framework provides the ability for applications to choose among multiple, controlled levels of delivery service for their data packets. It can provide hard QoS guarantee to individual traffic flows. To support this capability, two things

• Individual network elements (subnets and IP routers) along the path followed by an application's data packets must support mechanisms to control the quality of service

• A way to communicate the application's requirements to network elements along the path and to convey QoS management information between network elements and the

In the integrated services framework the first function is provided by QoS control services such as Controlled-Load (RFC2211, 1997) and Guaranteed (RFC2212, 1997). The second function may be provided in a number of ways, but is frequently implemented by a resource

The controlled load service is intended to support a broad class of applications which have been developed for use in today's Internet, but are highly sensitive to overloaded conditions. Important members of this class are the "adaptive real-time applications" currently offered by a number of vendors and researchers. These applications have been shown to work well on unloaded nets, but to degrade quickly under overloaded conditions. It is equivalent to "best effort service under unloaded conditions". The controlled-load service is intentionally minimal, in that there are no optional functions or capabilities in the specification. The service offers only a single function. It is better than best effort, but cannot provide strictly bounded

The controlled-load service can be implemented by using evolving scheduling and admission control algorithms. The implementations are highly efficient in the use of network resources. Guaranteed service guarantees that datagrams will arrive within the guaranteed delivery time and will not be discarded due to queue overflows, provided the flow's traffic stays within its specified traffic parameters. It is similar to emulate a dedicated virtual circuit. This service is intended for applications which need a firm guarantee that a datagram will arrive no later than a certain time after it was transmitted by its source. For example, some audio and video "play-back" applications are intolerant of any datagram arriving after their play-back time. Applications that have hard real-time requirements will also require guaranteed service.

algorithms:

**3.1.1 IntServ**

are required (**?**):

• ReSerVation Protocol (RSVP): • Differentiated Service (DiffServ)

delivered to those packets.

application must be provided.

service as guaranteed service.

reservation setup protocol such as RSVP (RFC2205, 1997).

• Multi Protocol Labeling Switching (MPLS)
