* By Ying weimin

QoS in UMTS Network

UMTS QoSUMTS QoS conceptQoS requirement on UMTSQoS mechanism in UMTS QoS in UMTS network UTRAN mechanism

CONTENT:

UMTS QoS concept Quality of Service (QoS) refers to the collective effect of service performance that determines the degree of satisfaction of the end-user of the service.

UMTS QoS conceptWhy UMTS QoS is so important -1G cellular system (AMPS) Analog voice/ circuit switch -2G cellular system (GSM) Digital voice/circuit switch -2.5G cellular system (GPRS) Digital data/ packet switch Address QoS issues but not required to implement. -3G cellular system (wcdma) Digital voice/data/ packet switch QoS features are designed in and ready for providing packet multi-medium service. Cellular system can server as mobile internet.

UMTS QoS conceptUMTS QoS classes(1) :

Conversational class speech, video telephony most delay sensitive Streaming class can tolerate some delay jitter should be minimized

Interactive class web browsing less stringent delay better error rate

UMTS QoS conceptUMTS QoS classe(2) :

Background class Email, downloads Error rate minimized Lower priority in scheduling than interactive class Uses resource only when interactive class dont need the them

UMTS QoS conceptDelay tolerantBit error tolerantbackgroundconversationalstreaminginteractiveUMTS QoS classe(3) :

UMTS QoS conceptQos impact on resourcesRequiredNetworkResourcesDelayDelayRequiredBufferingResources

UMTS QoS conceptQoS attibutes(1):Traffic Class: Conversational , Streaming, Interactive, Background; Traffic class indicates the type of application for which the UMTS bears is optimized. Max Bit Rate Maximum bit rate is defined as maximum number of bits delivered by the UMTS and within a period of time, divided by the duration of the period.Guaranteed Bit Rate Guaranteed bit rate is defined as the guaranteed number of bits delivered by the UMTS within a period of time, divided by the duration of the period.

UMTS QoS conceptQoS attibutes(2):Delivery Order Delivery order indicates whether the UMTS bearer service should offer in-sequence SDU delivery or not.Max SDU Size Maximum SDU size indicates the maximum allowed size of an SDU.Transfer Delay Transfer delay is defined as the maximum delay for the 95th percentile of the distribution of delay for all delivered SDUs during the lifetime of the bearer service.

UMTS QoS conceptQoS attibutes(3):SDU Format Information List of possible exact sizes of SDUs. SDU Error Ratio SDU error is defined as the fraction of lost or erroneous SDUs.Residual Bit Error Ratio Residual bit error ratio indicates the undetected bit error ratio in the delivered SDUs if error detection has been requested, otherwise it indicates the bit error ratio (BER) in the delivered SDUs.

UMTS QoS conceptQoS attibutes(4):Delivery of Erroneous SDUs Indicates whether SDUs detected as erroneous shall be delivered or discarded Traffic Handle Priority Specifies the relative importance for handling of all SDUs belonging to the UMTS bearer compared to the SDUs of other bearers. Allocation/Retention Priority Specifies the relative importance compared to other UMTS bearers for allocation and retention of the UMTS bearer. The Allocation/Retention Priority attribute is a subscription attribute which is not negotiated from the mobile terminal.

UMTS QoS conceptCall Setup Quality:Accessibility No coverageNetwork equipment downCell barredGeneric call setup failure (signaling or other reason)Call Blocking Probability A blocking event occurs when the network admission controller denies the users access attempt. Call Setup DelayThe call setup delay is measured from the time instant when the user places an access request, or query, to the instant when the user data exchange become possible with the other end of the call entity.

UMTS QoS conceptCall Quality ( Key parameters are covered by QoS Atributes )Acceptable Delay VariationThis is used to define how much jitter the application can tolerate, beyond which the packet is treated as being lost.Acceptable Transport Service Interruption DurationThis defines to what degree an interrupt to transport services is regarded as acceptable, provided it happens only occasionally during a call.Call Drop ProbabilityA call drop is defined as an event where the communication connection has

UMTS QoSUMTS QoS conceptQoS requirement on UMTSQoS mechanism in UMTS QoS in UMTS network UTRAN mechanism

CONTENT:

QoS requirement on UMTS

Conversational

voice and video

Voice messaging

Streaming audio

and video

Fax

E-mail arrival notification

FTP, still image,

paging

E-commerce,

WWW browsing,

Telnet,

interactive games

_989752100.doc

Error

tolerant

Error

intolerant

Conversational

(delay

QoS requirement on UMTSQoS attributers (Profile) :

QoS requirement on UMTSQoS example(1):AMR speech codec payloadBit rate:4,75 - 12,2 kbit/sDelay: end-to-end delay not to exceed 300ms BER: < 10-3FER< 1 % (with graceful degradation for higher erasure rates)

QoS requirement on UMTSQoS example(2):Videophone carries both video and audio and intended for use in a conversational environment. As such, in principle the same delay requirements as for conversational voice will apply, In fact, due to the long delays incurred in even the latest video codecs, it will be difficult to meet these requirements.Once again, the human eye is tolerant to some loss of information, so that some degree of packet loss is acceptable depending on the specific video coder and amount of error protection used. It is expected that the latest video codecs will provide acceptable video quality with frame erasure rates up to about 1%.

UMTS QoSUMTS QoS conceptQoS requirement on UMTSQoS mechanism in UMTS QoS in UMTS network QoS mechanism in UTRAN

CONTENT:

QoS in UMTSSubscriber#1PDP context #3PDP context #2PDP context #1-----------------PDP context IDAPN Qos Profile RNCSGSNGGSNUEHLRUMTS QOS Classes : Conversational class Steaming classInteractive classBackground class QoS profile configuration:

QoS in UMTS networkPDP context1233445555AttachPDP Context ActivationSubscribe timeIP Qos mapping & establishmentRAB establishmentQoS map to radio access bearers PDP modificationIP-QoS remapping if requiredRL/RB estabilishmentRRM to map QoS to channalsRNCSGSNGGSNUEHLRGeneral idea:

QoS in UMTS networkSubscriber#1PDP context #3PDP context #2PDP context #1-----------------PDP context IDAPN Qos Profile SGSNGGSNUEHLRSubscriber#1PDP context #3PDP context #2PDP context #1-----------------PDP context IDAPN PDP address Qos Profile 1.Attach Req2.Insert Sub.Data4.Attach Acpt3.Insert sub. Data Ack Subscribers attach to net work

QoS in UMTS networkSubscriber#1PDP context #3PDP context #2PDP context #1-----------------PDP context IDAPN PDP address Qos Profile SGSNGGSNUEHost RNC1 Activate PDP Context Req (QoS Req) 4 RAB Setup (QoS Neg) 5 RL/RB Establishment 6 RAB Est.Rsp 2 Activate PDP Context Req (QoS Neq) 3 Activate PDP Context Rsp (QoS Neq) SGSN may restrict requested QoSGiven its capabilities, load and theSubscribed QoSSGSN selects radio priority based on QoS negotiatedGGSN may further restrict the QoS given its capabilities and load RRM AlgorithmsAdmission control and QoS session establishment:

QoS in UMTS networkSubscriber#1PDP context #3PDP context #2PDP context #1-----------------PDP context IDAPN PDP address Qos Profile SGSNGGSNUEHost RNC9 Active PDP context Acpt (QoS Neg) 7 Update PDP Context Req (QoS Neq) 8 Update PDP Context Rsp (QoS Neq) In case QoS was downgraded by RNC , SGSN may inform GGSN about the new QoSMS either accepts the QoS or deactivates the PDP contextAdmission control and QoS session establishment:

QoS in UMTS networkNew SGSNOld SGSNUEGGSN RNC5 RA Update Acpt / Complete 1 RA Update Req 4 Update PDP Context Rsp (QoS Neq) 2 SGSN Context Req/Ack.(QoS profile) 3 Update PDP Context Req (QoS Neq) Inter SGSN RA update:

QoS in UMTS networkOld SGSNNew SGSNUEGGSN Target RNC6 Relocation command 1 Relocation required (Source ID, target ID, SRNC-TRNC container) 4 Relocation Req ack ( RABS ok, RABS fail) 2 Forward Rel. Req( PDP Context) 3 Relocation Req (SRNC-TRNC container,RABS) Serving RNC Relocation: Source RNC5 Forward Rel. Rsp 7 Relocation commit 8 Relocation of data Establishment of RABs, RBs

QoS in UMTS networkOld SGSNNew SGSNUEGGSN Target RNC15 Iu release command 9 Relocation detect 12 Relocation Comlete10 Update PDP context Req(Qos.neq) Source RNC13 Forward Rel. comp 11 Update PDP context Rsp

14 Forward Rel. comp.ack 16 Iu release complete Serving RNC Relocation:

UMTS QoSUMTS QoS conceptQoS requirement on UMTSQoS mechanism in UMTS QoS in UMTS network QoS mechanism in UTRAN

CONTENT:

QoS mechanism in UTRANPHYMACRLCRRCPDCPBMCL1L2L3Signaling Radio BearersUser Plane Radio BearersTransport channelLogical channelRadio interface protocals:

QoS mechanism in UTRANPDCP

Packet data convergence protocol :Header compression and decompression of IP data stream.Maintenance of PDCP sequence number for radio bearers that are configured to support lossless SRNS relocation.

QoS mechanism in UTRAN RLC

RLC mode Transparent mode : no overhead is added to higher layer data. Unacknowledged mode: no retransmission protocol is used and data delivery in not guaranteed. Acknowledged mode: Automatic repeat request (ARQ) mechanism is used for error correction.RLC function: segmentation and reassemble ; ARQ error correction ciphering

QoS mechanism in UTRANMAC function: Priority handling between different data flow is done by MAC; Transport Formation Selection , It control transport format for each flow.

QoS mechanism in UTRANMapping from QoS attributers to radio resource