QoS in Wireless

QoS in Wireless Networks Slide 1

QoS in Wireless NetworksELG5125 Presentation

Author: Thanh Cao

email: [email protected]: November 29, 2005

Key Factors Affecting M&A Slide 2QoS in Wireless Networks Slide 2

Problem Statement

• Report on schemes, specification to ensure, manage QoS in third- generation (3G) wireless networks, specifically in:

- UMTS QoS,- End-to-end QoS.- QoS mapping


Outlines

• Evolution towards 3G

• Factors affecting QoS

• QoS Techniques– Specifications– Converting transport to IP– IP mapping

• Conclusion


Why 3G?

• Higher data rates (up to 2 Mbps)• Supports QoS• Based on standardized protocols, interfaces

– “unifies” competing protocols, technologies

• Offers multimedia services: voice, data, video • Based on data packets, packet switching

– Data traffic will be dominating– Evolving toward all-IP networks


Evolution towards 3G (Ref [2], [3])

TDMA

GSM

CDMA one

IS-136B/HS

IS-95

IS-95B

CDMA2000

3GPP2

3GPP

IMT-2000

UMTS

GPRS EGPRS

EDGE

GPRS

UWC-136

3G(2001-?) 2.5G(1998-?) 2G(1997-?)


3G Evolution: TDMA

• TDMA evolves into 3G wireless by UWC-136, which is based on IS-136/IS-136+ and IS-136 High Speed (IS-136HS).

• IS-136+ improves the voice and data services which currently use the existing 30-kHz channel bandwidth.

– IS-136+ packet data service is based on the GSM General Packet Radio Service (GPRS) architecture.

• IS-136 High Speed (IS-136HS) has two flavors: outdoor/vehicular and indoor.

– The outdoor 136HS is similar to the Enhanced Data rates for GSM Evolution (EDGE), and provides bit rates up to 384 kbps.

– The indoor 136HS provides bit rates up to 2 Mbps.


3G Evolution: CDMA

• IS-95, often referred to as North American CDMA (NA-CDMA), has two migration paths: IS-95B and cdma2000.

– Both IS-95B and cdma2000 provide smooth transition to IMT-2000 while maintaining backward compatibility with existing IS-95 infrastructure.

• IS-95B provides enhanced data rate by allowing transmission/reception of data on multiple channels.

– data rate up to 76.8 kbps or 115.2 kbps in either the uplink or downlink direction.

• Cdma2000 or wideband cdmaOne – Further enhancement of IS-95B,– Uses multi-carriers,– includes wider channel bandwidth, a pilot channel, and power control


3G Evolution: GSM

• GSM networks will enhance data services in three phases: General Packet Radio Services (GPRS), Enhanced Data rates for GSM Evolution (EDGE) and Wideband CDMA (WCDMA).

• GPRS allows GSM mobile subscribers to connect to an IP-based or X25-bases networks.

• EDGE has been approved by ETSI and UWCC as the outdoor/vehicular component of IS-136HS.

– EDGE is backward compatible with GSM/GPRS infrastructure.

• Wideband CDMA introduces a new air interface based on 5-MHz channel bandwidth.

– WCDMA is adopted as the air interface for 3G wireless (IMT-2000)– See IMT-2000 next


3G Global Standard IMT-2000

• International Mobile Telecommunication (IMT-2000)– An ITU development activity with contributions from:

• Japan: Association for Radio Industry and Business (ARIB)• EU: European Telecommunications Standard Institute (ETSI)• USA: Telecommunications Industry Association (TIA)• Korea: Telecommunications Technology Association (TTA)

– A family of standards that will provide at least• 384 kbps at pedestrian speed,• 144 kbps at mobile speed,• Up to 2 Mbps indoor.

– Adoption of Wideband CDMA with three optional modes: • Direct Sequence Frequency-Division Duplex (ETSI, ARIB)• Multi-carrier FDD (TIA)• Direct Sequence Time-Division Duplex (ETSI)


Summary of Wireless Evolution

• IMT-2000 standard,• data rates from 144

kbps to 2 Mbps,• enhanced

multimedia messaging,

• MPEG-4 video,• location-based

services (GPS-enabled),

• mobile computing

• intermediate technology

• modifications to 2G phone architectures (e.g. GPRS from GSM),

• more advanced data services.

• move to digital,• radical changes to

architecture and components,

• main services: voice, text-based short message service (SMS)

• “first” generation• only voice

services offered

3G2.5G2GAnalog

Summary of Wireless Evolution

Source: RD Gitlin, “Next Generation Wireless Networking Presentation,” 2003, Columbia University.


Why QoS in wireless?

• IP QoS technologies have moved beyond “Best effort”; wireless must interoperate with IP QoS; therefore wireless must provide QoS.

• New coming services requiring QoS:– Streaming applications need throughput and delay guarantees,– Real-time applications (e.g. multimedia) need low delay,– Other applications with different QoS requirements.

• Network Operators:– Efficient use of network resources: avoid over-provisioning– Service differentiating: offering Service Level Agreement

• Major QoS components: throughput, delay, jitter, error rates


Factors Affecting Wireless QoS

• QoS of wireless network is affected by the following:– Attenuation,– Multi-path interference,– Spectrum interference: for example spread-spectrum

interferences from neighboring cells,– Noise: Noise sources can be natural and man-made such as

radio, TV and other radio-frequency transmission,– Mobility: affects hand-over and resource utilization,

management,– Limited capacity: resources are costly.

• Higher error rates are typical

• QoS schemes must interact with those already in use in the Internet


Air Interface QoS Mechanisms

Packet arrival

Mapping

Admissioncontrol

Scheduling & resource allocation

Monitoring(QoS Parameters)

Channel Condition (from physical layer)

QoS mechanisms: - mapping, admission control, scheduling, resource allocation.- have to monitor and react to the environment in real time


Core Network QoS Components

• Admission Control: Limits number of flows admitted into the network so that each individual flow obtains its desired QoS.

• Scheduling:– Scheduling affects delay, jitter and loss rate.– Allows protection against misbehaving flows.


Core Networks QoS Components

• Buffer Management: Controls the buffer size and decides which packets to drop. – Controls packet loss rate.– There are many packet drop strategies including weighted

Random Early Detection (RED).

• Congestion Control: Prevents, handles and recovers from network congestion scenarios.


UMTS Networks Reference Architecture (Ref [3])

UE

UE

BSS/GERAN

UTRAN

SGSN GGSN

Multimedia IP networks

Servers, gateways, and control/signaling

Alternate access networks

MGW MGW

PSTN/ legacy/ external networks

Servers, gateways and control

Applications & services

Applications & services


End-to-End QoS Architecture (Ref [6])

UMTS

TE TE MT RAN

CN EDGE NODE

CN Gateway

End-to-End Service

UMTS Bearer Service TE/MT Local Bearer Service

External Bearer Service

Radio Access Bearer Service CN Bearer Service

Radio Bearer Service

RAN Access Bearer Service

Backbone Bearer Service

Physical Radio Bearer Service

Physical Bearer Service


Specifying UMTS Traffic Classes

UMTS QoS Traffic Classes and Applications (Ref [5])

Emails, SMS, background download

Web browsing

Streaming audio, video

Voice, voice over IP, video conferences

Application examples

Destination does not expect data within a certain time

Preservation of payload contents

Expect response to request

Preservation of payload contents

Preservation of time relation between info entities

Conversational pattern (low delay)

Preservation of time relation between info entities

Fundamental Characteristics

BackgroundInteractiveStreaming ConversationalTraffic Class


Specifying UMTS Attribute Values

Attribute Value Ranges for UMTS Bearer Attributes (Ref [5])

Yes/noSignaling indication

Speech/unknownSpeech/unknownSource stats descriptor

1,2,31,2,31,2,31,2,3Allocation/retention of priority

1,2,3Traffic handling priority

<= 2,000<= 2,000Guaranteed bit rate

300 (max)100 (max)Transfer delay (ms)

Yes/noYes/noYes/noYes/noDelivery of erroneous SDU

10-3, 10-4, 10-610-3, 10-4, 10-610-1, 10-2, 7*10-3, 10-3, 10-4, 10-5

10-2, 7*10-3, 10-3, 10-4, 10-5

SDU error ratio

TBDTBDSDU format info

<= 1500, 1502<= 1500, 1502<= 1500, 1502<= 1500, 1502Max SDU size

Yes/noYes/noYes/noYes/noDelivery order

2,000 - overhead 2,000 - overhead2,000 2,000Max bit rate (kbps)

BackgroundInteractiveStreamingConversationalTraffic Class


UMTS Attribute Mapping

• UMTS – Radio Access Bearer mapping:– Same values between UMTS and Radio Access Bearer: max bit

rate, delivery order, delivery of erroneous SDUs, guaranteed bit rate, traffic handling priority, maximum SDU size, SDU format information.

– Left as an implementation issue: residual BER, SDU error ratio, transfer delay, SDU format information, and source statistics descriptor.

• Other Attribute Mappings– Attribute mapping from application attributes into UMTS bearer

service is left as an operator or implementation issue.– Attribute mapping from UMTS bearer service to CN bearer service

is left as an operator issue.


Radio Access Networks

Core Network

SRNC

CRNC

Node B Node B Node B

UE

RNS

RAN

SRNC

CRNC

Node B Node B Node B

RNS

RAN consists of many RNS, among which UE can roam (Ref [9])


IP as Transport in the RAN

• Current UMTS Terrestrial Radio Access Network (UTRAN) uses AAL2/ATM technology.

• Cases for IP as transport technology:– IP QoS is approaching maturity– IP network layer is independent of link, physical layers so it

can support a wide selection of lower layers– IP is becoming basis for packetization of voice, data,

signaling, operation, administration and management (OAM) functions,

– 3G Core Network is already mostly IP-based.


IP QoS: DiffServ

• There are several IP QoS technologies: over-provisioning, DiffServ, IntServ, MPLS, RSVP– IntServ: fine control resolution, not scalable– DiffServ: simple management, scalable

• DiffServ: allows network operators to offer different QoS to different traffic streams– Prioritizes via DiffServ Code Point (DSCP) in IP header,– Aggregates traffic into Per Hop Behavior (PHB) groups – Two types of routers: edge and core

• Pushes complexity to edge routers (classification; policing, shaping, scheduling traffic)

• Simple core routers process based on PHB. Basic PHBs: Premium Forwarding/Expedite Forwarding (PF/EF), Assured Forwarding (AF), Best Effort (BE)


IP in the RAN

• Therefore, IP is being considered for UTRAN, facilitating end-to-end QoS, signaling, OAM.

• Mobile Wireless Internet Forum studied and concluded that IP is a viable transport option (Ref [9])

• Challenges: tight end-to-end delay, jitter, low packet loss ratio


QoS in Core Network

• QoS in core network is left mostly to the operators:– Which and where QoS capabilities are implemented, – Mapping between DiffServ code points and UMTS traffic

classes,

• Inter-operation between operators will be based on Service Level Agreement


Mapping UMTS Classes to IP DiffServ

• Proposal for mapping UMTS Traffic Classes to IP DiffServ:

- Ref [8] proposes Resource Control Layer (RCL) to expand UMTS Interactive traffic class due to:

- Traffic handling priority- Packet loss rate

- Ref [8] proves that QoS is handled more efficient when UMTS QoS classes are mapped to RCL classes than mapping UMTS QoS directly to DiffServ classes.


Mapping UMTS Traffic Classes to IP DiffServ

AF2 or AF1 or BE PMC BE Background

1500 =< 1500, 1502Max packet size (bytes)

< 10-4 10-3, 10-4, 10-6 Packet error ratio

Max. per flow 50 No QoS guarantees

< 2048 - overheadMax bit rate (kb/s)

1 2, 31, 2, 3 Traffic handling priority

<10-3 < 10-4 10-3, 10-4, 10-6 Packet error ratio

1500 1500 =< 1500, 1502 Max packet size (bytes)

Max. per flow 250 Max. per flow 50< 2048 - overhead Max bit rate (kb/s)

AF3 PMM PMC Interactive

250 (max) 250 (max) Transfer delay (ms)

< 10-6 10-1, 10-2, 7*10-3, 10-3, 10-4, 10-5 Packet error ratio

1000 =< 1500, 1502 Max packet size (bytes)

Max. per flow 1000 < 2048 Max bit rate (kb/s)

AF4 PVBR Streaming

150 (max) 100 (max) Transfer delay (ms)

< 10-8 10-2, 7*10-3, 10-3, 10-4, 10-5 Packet error ratio

256 =< 1500, 1502 Max packet size (bytes)

Max. per flow 200 < 2048 Max bit rate (kb/s)

AF and EF PHBs PCBRConversationalCharacteristics

DiffServRCLUMTS Class


Conclusion

• IMT-2000 tries to include, unify, inter-operate, standardize diversified and competing protocols, technologies,– 3GPP defines a QoS framework– We are evolving toward all-IP solution

• Many issues are still unresolved or intentionally left as “implementation, operator issues”– QoS in the Air Interface is still unresolved.


[1] Chen L., Kayama H., Umeda N., “Power Resource Cooperation Control Considering Wireless QoS for CDMA Packet Mobil Communication Systems,“ The 13th IEEE International Symposium on Personal, Indoor, and Mobile Radio Communication, 2002. [2] Dahlman E, Beming P, Knutsson J, Ovesjo F, Persson M, Roobol C, “WCDMA – The Radio Interface for Future Mobile Multimedia Communications,” IEEE Transactions on Vehicular Technology, Vol 47, No. 4, November 1998.[3] Desposito J, “A Bump in the Path to 3G,” Electronic Design Online ID #3467, May 15, 2000.[4] Dixit S, Guo Y, Antoniou Z, “Resource Management and Quality of Service in Third Generation Wireless Networks,” IEEE Communications Magazine Feb 2001, pp 125 – 133.[5] ETSI, 3GPP, “Quality of Service Concept and Architecture,” 3GPP TS 23.107 version 6.3.0 Release 6.[6] ETSI, 3GPP, “End-to-End Quality of Service Concept and Architecture,” 3GPP TS 23.207 version 6.6.0 Release 6.

References


References (cont’d)

[7] Guo JY, Chaskar H, “Class-Based Quality of Service over Air Interfaces in 4G Mobile Networks,” IEEE Communications Magazine, March 2002, pp 132 - 137.

[8] Maniatis SI, Nikolouzou EG, Venieris IS, “QoS Issues in the Converged 3G Wireless and Wired Networks,” IEEE Communications Magazine, August 2002.

[9] Mobile Wireless Internet Forum, “IP in the RAN as a Transport Option in 3rd Generation Mobile Systems,” Release 2.0.0, Reference number MWIF 2001.084.

[10] Saud L.C., Limos R.P., “Third Generation Mobile Wireless Networks Quality of Service, with a 2.5G Case Study Using Differentiated Service,” IEEE/Sarnoff Symposium on Advances in Wired and Wireless Communications, April 26 – 27, 2004, pp 71-74.

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