QoS in Wireless Networks ELG5125 Presentation Author: Thanh Cao email: [e-mail] Date: November 29, 2005

1
QoS in Wireless NetworksELG5125
PresentationAuthor Thanh Caoemail
thanhkcao_at_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
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
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
UMTS QoS Traffic Classes and Applications (Ref
5)
19
Specifying UMTS Attribute Values
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
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
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 (contd)

• 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.