QoS in Wireless Networks ELG5125 Presentation Author: Thanh Cao email: thanhkcao@gmail Date: November 29, 2005

1. QoS in Wireless NetworksELG5125 PresentationAuthor: Thanh Caoemail: thanhkcao@gmail.comDate: November 29, 2005

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

3. Outlines • Evolution towards 3G • Factors affecting QoS • QoS Techniques • Specifications • Converting transport to IP • IP mapping • Conclusion

4. 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

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

6. 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.

7. 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

8. 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

9. 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)

10. Summary of Wireless Evolution Analog 2G 2.5G 3G • “first” generation • only voice services offered • move to digital, • radical changes to architecture and components, • main services: voice, text-based short message service (SMS) • intermediate technology • modifications to 2G phone architectures (e.g. GPRS from GSM), • more advanced data services. • IMT-2000 standard, • data rates from 144 kbps to 2 Mbps, • enhanced multimedia messaging, • MPEG-4 video, • location-based services (GPS-enabled), • mobile computing Summary of Wireless Evolution Source: RD Gitlin, “Next Generation Wireless Networking Presentation,” 2003, Columbia University.

11. 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

12. 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

13. Air Interface QoS Mechanisms Packet arrival Monitoring (QoS Parameters) Mapping Admission control Scheduling & resource allocation Channel Condition (from physical layer) QoS mechanisms: - mapping, admission control, scheduling, resource allocation. - have to monitor and react to the environment in real time

14. 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.

15. 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.

16. UMTS Networks Reference Architecture (Ref [3])

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

18. Specifying UMTS Traffic Classes Traffic Class Conversational Streaming Interactive Background Fundamental Characteristics Conversational pattern (low delay) Preservation of time relation between info entities Preservation of time relation between info entities Expect response to request Preservation of payload contents Destination does not expect data within a certain time Preservation of payload contents Application examples Voice, voice over IP, video conferences Streaming audio, video Web browsing Emails, SMS, background download UMTS QoS Traffic Classes and Applications (Ref [5])

19. Specifying UMTS Attribute Values Traffic Class Conversational Streaming Interactive Background Max bit rate (kbps) 2,000 2,000 2,000 - overhead 2,000 - overhead Delivery order Yes/no Yes/no Yes/no Yes/no Max SDU size <= 1500, 1502 <= 1500, 1502 <= 1500, 1502 <= 1500, 1502 SDU format info TBD TBD SDU error ratio 10-2, 7*10-3, 10-3, 10-4, 10-5 10-1, 10-2, 7*10-3, 10-3, 10-4, 10-5 10-3, 10-4, 10-6 10-3, 10-4, 10-6 Delivery of erroneous SDU Yes/no Yes/no Yes/no Yes/no Transfer delay (ms) 100 (max) 300 (max) Guaranteed bit rate <= 2,000 <= 2,000 Traffic handling priority 1,2,3 Allocation/retention of priority 1,2,3 1,2,3 1,2,3 1,2,3 Source stats descriptor Speech/unknown Speech/unknown Signaling indication Yes/no Attribute Value Ranges for UMTS Bearer Attributes (Ref [5])

20. 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.

21. Radio Access Networks Core Network RNS SRNC RNS SRNC CRNC CRNC RAN Node B Node B Node B Node B Node B Node B UE RAN consists of many RNS, among which UE can roam (Ref [9])

22. 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.

23. 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)

24. 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

25. 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

26. 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.

27. Mapping UMTS Traffic Classes to IP DiffServ UMTS Class RCL DiffServ Characteristics Conversational PCBR AF and EF PHBs Max bit rate (kb/s) < 2048 Max. per flow 200 Max packet size (bytes) =< 1500, 1502 256 Packet error ratio 10-2, 7*10-3, 10-3, 10-4, 10-5 < 10-8 Transfer delay (ms) 100 (max) 150 (max) Streaming PVBR AF4 Max bit rate (kb/s) < 2048 Max. per flow 1000 Max packet size (bytes) =< 1500, 1502 1000 Packet error ratio 10-1, 10-2, 7*10-3, 10-3, 10-4, 10-5 < 10-6 Transfer delay (ms) 250 (max) 250 (max) Interactive PMMPMC AF3 Max bit rate (kb/s) < 2048 - overhead Max. per flow 250Max. per flow 50 Max packet size (bytes) =< 1500, 1502 1500 1500 Packet error ratio 10-3, 10-4, 10-6 <10-3 < 10-4 Traffic handling priority 1, 2, 3 1 2, 3 Background PMCBE AF2 or AF1 or BE Max bit rate (kb/s) < 2048 - overhead Max. per flow 50 No QoS guarantees Max packet size (bytes) =< 1500, 1502 1500 Packet error ratio 10-3, 10-4, 10-6 < 10-4

28. 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.

29. References [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.

30. 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.