Quality of Service (QoS) in 3GPP

1. Quality of Service (QoS) in 3GPP

2. UMTS QoS Architecture • UMTS QoS Management • UMTS QoS Classes • QoS Attributes (QoS Profile) • Management of End-to-End IP QoS

3. 1. UMTS QoS Architecture • 3GPP TS 23.107 defines 3GPP QoS architecture with the following major QoS principles • QoS has to be provided end-to-end • the QoS attributes are needed to support asymmetric bearers • the number of user-defined and controlled attributes should be as small as possible • the derivation and definition of QoS attributes from the application requirements have to be simple • it should be able to provide different levels of QoS using UMTS-specific control mechanisms that are not related to QoS mechanisms in the external networks

4. the QoS mechanisms have to allow efficient use of radio capacity and efficient resource utilization • it should allow independent evolution of core and access networks • the UMTS network should be evolved with minimized impact on the evolution of transport technologies in the wireline networks • the UMTS QoS control mechanisms shall be able to efficiently interwork with current QoS schemes

5. the overhead and additional complexity caused by the QoS scheme should be kept reasonably low, so as the amount of state information transmitted and stored in the network • the QoS behavior should be dynamic, i.e., it should be possible to modify QoS attributes during an active session

6. UMTS QoS Architecture

7. QoS functions are divided into different layers • Each bearer service provides its QoS services by utilizing the services furnished by lower layer(s) • End-to-end QoS • Terminal Equipment (TE) to Mobile Terminal (MT) Local Bearer Service • UMTS Bearer Service • External Bearer Service

8. UMTS Bearer Service • Radio Access Bearer Service • provides confidential transport of signaling and user data between MT and CN Iu Edge Node • Core Network (CN) Bearer Service • connects the UMTS CN Iu Edge Node with the CN Gateway to the external network • should efficiently control and utilize the backbone network in order to provide the contracted UMTS Bearer Service • the packet core network should support different backbone bearer services for a variety of QoS

9. 2. UMTS QoS Management • Management of the UMTS Bearer Service includes management functions in control plane and user plane • Management functions • seek to ensure the negotiated QoS between UMTS Bearer Service and external services, including TE/MT Local Bearer Service and External Bearer Service • End-to-end QoS is achieved by • translation and mapping of the QoS requirements and QoS attributes between the UMTS Bearer Service and external services

10. UMTS QoS management in control plane

11. Control Plane • Four major functional blocks in control plane • Bearer Service Manager • 功用 • 主要功能是協調控制信號以建立，修改，並且維持所要求的QoS品質服務 • 每個BS manager都是一個包含著多個物件管理者(component managers)的組合體，而這些物件管理者(component managers)各自管理自己所屬功能，例如，UMTS, radio, Iu, and CN BS manager • 另一些BS manager負責QoS品質服務參數數值的轉換 • 在提供QoS品質服務前，每個BS manager可能會與admission control entity相互溝通。溝通的目的在於判斷使用者所要求的頻寬資源是否可獲得

12. 分類 • UMTS Bearer Service (BS) Manager • Radio Access Bearer (RAB) Manager • Local Bearer Service (BS) Manager • Radio Bearer Service (BS) Manager

13. Translation Function • 將外部的信號轉換成內部的信號，並且將它們轉送至下一層的BS management，其中還包含了傳輸相關參數屬性的轉換

14. Admission/Capability Control • 維持有關頻寬資源的獲得及配置的相關資訊，並在當使用者提出頻寬保留要求時，決定是否給予頻寬資源的保留配置 • 在CN EDGE中的admission control model主要是負責對使用者所提出的PDP context和QoS參數值做最後的接受或拒絕的決定

15. Subscription Control • 讓CN EDGE的BS manager透過它來做確認，以決定是否有使用網路QoS服務的使用權

16. To establish or modify a UMTS bearer service • the Translation Functions in the MT and the Gateway signal / negotiate with external bearer services • the service primitives and QoS attributes are converted between the UMTS Bearer Service and the external bearer services • the Translation Functions further signals/negotiates with the UMTS BS Managers in MT, CN Edge, and Gateway

17. Each UMTS BS Manager consults with its associated Admission/Capability Control to decide whether the requested services and desired resources are available and can be granted • the UMTS BS Manager in CN Edge also consults with the Subscription Control to check the administrative privileges for the requested services • once all checks are positive, a UMTS bearer service could be established/modified • each UMTS BS Manager requests services from lower layers and translates its service attributes to lower layers

18. example • the UMTS BS Manager in MT requests services from the Local BS Manager and the Radio BS Manager • the UMTS BS Manager in Gateway asks services from the CN BS Manager and the External BS Manager • in addition to the Iu BS manager and the CN Manager in the CN Edge, the UMTS BS Manager in CN Edge translates QoS attributes and requests services from the RAB Manager in UTRAN as well • the RAB Manager in UTRAN verifies with its associated Admission/ Capability Control to determine whether the requested services are supported and the desired resources are available

19. UMTS QoS management in user plane

20. User Plane • User plane • ensures that the user data transmitted in UMTS Bearer Service conforms to the traffic characteristics and service attributes defined by the control plane

21. Four major components • Classifier • 依據使用者QoS品質服務需求來分類並指派封包 • 例如，依據DiffServ (Differentiated Services)的DSCP (Differentiated Service Code Point)或TCP port number來給予不同等級的品質服務 • Classifier分別存在於MT及Gateway中，各自負責指派並分配來自local bearer service和external bearer service的封包

22. Conditioner • 為一個監督者的角色，隨時監看資料傳輸的狀態，檢查資料是否符合所給予的QoS等級，若不符合則丟棄或重新給予標記 • conditioner藉由塑型(traffic shaping)或政策管理(traffic policing)來達成目標控制 • Mapper • 依據QoS品質服務的要求給予每個資料單元特殊的QoS品質服務的標記 • marks data in order to receive the intended QoS

23. Resource manager • responsible for managing and distributing resources according to the QoS requirements • include scheduling, bandwidth management, and power control for the radio bearer

24. Before entering the domain of UMTS Bearer Service, traffic is classified and conditioned in the MT and the Gateway • Based on packet header or traffic characteristics, data are classified into different UMTS bearer services • They are then conditioned to ensure conformance with the negotiated QoS

25. For downlink traffic to MT, there is also a traffic conditioner in UTRAN • The conditioner in the Gateway is for conditioning traffic that enters the core network from external networks • The output traffic from the conditioner in the gateway may not conform with the QoS attributes specified for downlink traffic in the UTRAN • packets may be shaped or dropped • shaping: the process of delaying packets within a traffic stream to cause it to conform to some defined traffic profile • dropping: the process of discarding packets based on specified rules

26. 3. UMTS QoS Classes • 3GPP define two major classes (according to delay sensitivity) • real time • conversational class • streaming class • non-real time • interactive class • background class

27. real-time traffic is more delay sensitive than is non-real-time traffic • conversational class is most sensitive to delay, followed by streaming class, interactive class, and then background class

28. UMTS QoS Classes

29. 4. QoS Attributes (QoS Profile) Bearer services discussed for QoS attributes

30. QoS attributes in UMTSbearer service

31. Attributes • delivery order • whether the SDU (Service Data Unit) should be delivered in order • maximum SDU size • the maximum allowable size of SDUs • SDU format information • the possible actual sizes of SDUs, which might be useful for RLC operation in UTRAN • SDU error ratio • the fraction of lost or detected erroneous SDUs

32. residual bit error ratio (BER) • the undetected bit error ratio of a delivered SDU • delivery of erroneous SDUs • whether the detected erroneous SDU should be transmitted • transfer delay • the maximum delay of 95th percentile of the delay distribution of all delivered SDUs • traffic handling priority • the priority for SDUs

33. allocation/ retention priority • the priority for allocation and retention of the UMTS bearer • source statistics descriptor • shows the traffic characteristics of SDUs • studies have shown that speech holds a discontinuous behavior, in which there are talking and silent periods • by specifying the source characteristics, it helps the system in making a decision for admission control to achieve statistical multiplex gain

34. Values of UMTS bearer service attributes

35. QoS attributes in RAB (radio access bearer) service

36. Values of RAB (radio access bearer) service attributes

37. 5. Management of End-to-End IP QoS • Assuming the external network is based on IP, this section discusses the management and interaction between the UMTS Bearer Service and the External Bearer Service to provide end- to-end IP QoS

38. Control plane for end-to-end IP QoS management

39. Two extra components in the control plane of the management function to provide end-to-end IP QoS • IP BS (Bearer Service) Manager • P-CSCF (Proxy Call State Control Function)

40. IP BS Manager • controls the external IP bearer service • utilizes standard IP mechanisms to manage IP bearer services • to interact with UMTS Bearer Service, the IP BS Manager leverages the Translation Function to map the mechanisms and parameters used within the IP bearer service to those used within the UMTS bearer service

41. Two IP BS Managers • one in the UE (User Equipment) • one in the Gateway (the Gateway might be a GGSN) • the IP BS Managers in the UE and the GGSN could communicate with each other using relevant signaling protocols

42. IP BS Manager may support Int-Serv/RSVP or Diff-Serv edge function • Diff-Serv edge function • required for the IP BS Manager in GGSN • optional for the IP BS Manager in UE • Int-Serv/RSVP • optional for both UE and GGSN

43. PEP (Policy Enforcement Point) function defined in IP policy framework • optional for UE • mandatory for GGSN

44. Capability of IP BS managers in UE and GGSN

45. P-CSCF • a mobile’s first contact point for IP multimedia sessions • essentially is a local SIP server • includes a Policy Control Function (PCF) • PCF • coordinates the applications with the resource management in IP layer • a logical entity for policy decision, which conforms to the policy framework defined by IETF • effectively is a PDP (Policy Decision Point), whereas the IP BS Manager in GGSN is a PEP (Policy Enforcement Point)

46. Go interface • the interface between PCF and GGSN • supports the transfer of information and policy decisions between PCF and IP BS Manager in the GGSN

47. QoS resource authorization for IP bearer service • SIP adopted by 3GPP as the signaling protocol for packet domain • the QoS authorization process is triggered when receiving a SIP message • the payload of a SIP INVITE usually contains SDP (Session Description Protocol), which specifies the type of media, codec, sampling rate, etc.

48. PCF identifies the connection information such as media and bandwidth requirements for a downlink connection • PCF then relays the SDP message to the destining UE • once the SDP from destining UE is received, the PCF identifies the uplink connection information • it also authorizes the requested QoS resources and enforces the IP bearer policy • the SDP message is then forwarded to the originating UE

49. Radio Resource Management (RRM) • Radio Resource Management (RRM) algorithms are responsible for efficient utilization of the air interface resources • RRM is needed to guarantee Quality of Service (QoS), to maintain the planned coverage area, and to offer high capacity