Quality of Service (QoS) Best Practices for CDMA2000 1xEV-DO Networks

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Quality of Service (QoS) Best Practicesfor
CDMA2000 1xEV-DO Networks

• Engineering Services Group QUALCOMM, Inc.

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• Introduction to QoS

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What is QoS?

• QoS is a practice, that refers to the capability
  of a network to provide
• Differentiated service to a selected group of
  user applications or for specific types of
  network traffic over
• Various transport technologies and across all
  communication segments
• QoS allows users with different OSI application
  layer needs to meet their service requirements
  while utilizing the available network resources
  efficiently
• QoS is IP data networking done right, to ensure
  consistent good user experience

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Why implement QoS?

• The future Everything over IP and IP on
  Everything
• More, more and more applications, access and core
  network elements are migrating to IP based
  services and architecture

• Implementing QoS in IP networks
• Ensures a consistent good user experience
• Enables new differentiated services and classes
  of service that were previously not feasible
• Supports tailored services for operator
  differentiation
• Allows coexistence of business-critical
  applications alongside interactive multimedia and
  voice applications
• Provides more efficient resource control and
  usage
• Is the foundation of the fully integrated network
  of the future

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How is QoS achieved?

• QoS is achieved by optimal implementation of
• Packet Classification
• Link Efficiency
• Queue Management
• Congestion Management
• Traffic Shaping and Policing
• Admission Control
• Every communication segment and network elements
  across all these communication segments must
  perform their share of QoS function
• Air interface, backhaul and IP backbone are few
  examples communication segments
• BTS, RAN, PDSN and Routers are few examples of
  network elements

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QoS Application Criteria

• The four horsemen of an QoS applications are
• Target Throughput (kbps) The minimum data rate
  at which usable data can be sent over the
  communication path from the origination to the
  destination
• Delay/Latency (ms) Maximum allowable delay
  between sending a packet at the origination and
  reception of that packet at the destination
• Jitter The statistically tolerable variance of
  inter-arrival delay between two consecutive
  packets within the same IP flow/stream
• Reliability/PER () The number of packets that
  are in error out of the total number of packets
  transmitted
• The mechanism to honor the above per application
  requirements is Quality of Service (QoS)

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Examples of QoS Applications

• Applications with flows that require QoS
  treatment are
• Voice over IP (VoIP)
• Full-duplex communication with two flows control
  and speech
• Packet Switched Video Telephony (PSVT)
• Full-duplex communication with three flows
  control, audio and video
• Video Streaming (VS)
• Half-duplex communication with three flows
  control, audio and video
• Push to Talk (PTT)
• Half-duplex communication with two flows control
  and audio
• Rapid connection and paging
• Low Latency Games
• Full-duplex communication with one flow control

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• Evolution of QoS in
• CDMA2000 1xEV-DO Networks

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QoS in a typical 1xEV-DO Network Architecture
QoS
Core Data Network QoS (Typically DiffServ
mechanism)
R-P Interface QoS (Typically IP over Ethernet)
Air Interface QoS
Packet Marking and Classification
Backbone QoS (Typically IP over OC-3)
Backhaul QoS (Typically IP over T1)
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QoS in 1xEV-DO Rel 0 Networks User-based

• User-based QoS in 1xEV-DO Rel 0 systems
• Enables the system to treat users with different
  levels of priority based on their subscription
  level (Executive, Premium, Standard)
• User profile determines priority level and
  available applications
• Different levels of priority based on the current
  application utilized
• Flexibility to switch priorities based on the
  applications launched
• Once priority established, all of the users
  application packets are treated with same
  priority
• Implemented with minimal software changes

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User-based QoS in 1xEV-DO Rel 0 Networks
Illustration
QoS
Core Data Network QoS (Typically DiffServ
mechanism)

• R-P Interface QoS
• QoS for A11 signaling
• User Profile based QoS on A10

• Air Interface QoS
• User-based
• Inter-AT QoS

Packet Marking and Classification

• Backhaul QoS
• QoS for Abis signaling
• QoS for different Users

• Backbone QoS
• Inherent application IP QoS
• Dependency on AT marking IP QoS

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QoS in 1xEV-DO Rev A Application-based

• Application-based QoS in 1xEV-DO Rev A systems
• Enables the system to treat applications with
  different levels of priority
• Same applications within and across ATs get the
  same priority.
• Implemented with an upgrade to 1xEV-DO Rev A
  system that provides

• 1xEV-DO Rev A Air interface features
• Multi-Flow Packet Application and Enhanced
  Multi-flow Packet Application
• Packet-based RLP
• ROHC
• Short Packets
• Multi-user Packets
• One-to-many mapping of DRC index to transmission
  formats
• NULL to non-NULL Rate DRC mapping
• DRC Translation Offset
• RTCMAC Subtype 3 algorithm
• RL Hybrid ARQ
• Data Source Control channel
• Improved Access Channel for rapid access

• 1xEV-DO Rev A RAN features
• QoS aware scheduler
• DRC/DSC Erasure mapping
• FL Delayed-ARQ
• Seamless handoff via Route Selection
• Sub-Synchronous Control Channel Cycle for fast
  paging
• Quick Connect
• 1xEV-DO Rev A PDSN features
• SO67 to forward IP packets to RAN
• Packet filters prioritization with Multiple
  A10s
• Authorization accounting

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Application-based QoS in 1xEV-DO Rev A Networks
Illustration
QoS
Core Data Network QoS (Typically DiffServ
mechanism)

• R-P Interface QoS
• QoS for A11 signaling
• Application Profile based QoS on Auxiliary A10

• Air Interface QoS
• QoS Negotiated
• Application-based
• Intra and Inter-AT

Packet Marking and Classification

• Backbone QoS
• Inherent application IP QoS
• Rely on PDSN marking IP QoS

• Backhaul QoS
• QoS for Abis signaling
• QoS for different Applications

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QoS Evolution in 1xEV-DO 3GPP2 Framework SUMMARY
QoS Features 1xEV-DO Rel 0 1xEV-DO Rev A (Backward compatible to Rel 0) 1xEV-DO Rev B (Backward compatible to Rel 0 and Rev A)
Packet Classification User-based (UATI-based) Multi-Flow (MFPA) Enhanced Multi-flow (EMFPA) Multi-Flow RTCMAC (Subtype 3) Multi-Link Multi-Flow (MLMFPA) Multi-Carrier Traffic Channels
Link Efficiency FL Hybrid ARQ Short and Long PL Packets Multi-User Packets RL Hybrid ARQ Packet-based framing ROHC
Queue Management User-based Priority (Inter-AT) FL Proportional Fair Scheduler RL Rate Transition Probabilities Applications-based Priority (Inter-AT and Intra-AT) FL Generalized/Delay Fair RL RTCMAC algorithm (Transition\Priority Functions) Multi-Carrier Independent Queuing
Congestion Management Flow Control RED, WRED and Tail Drop mechanisms FL D-ARQ, DRC/DSC Erasure, NULL to non-NULL Rate map RL RTCMAC algorithm Enhanced Flow Control Multi-Carrier Load Balancing
Traffic Shaping and Policing _at_ PDSN User-based Profile Application-based Profile (FL Scheduler and RL Token-bucket algorithm)
Admission Control QoS Profiles and QoS Traffic Class based
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• QoS in 1xEV-DO Rev A Networks

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QoS Within a 1xEV-DO Rev A Framework

• The QoS required for an application with distinct
  IP Flows (such as PSVT Audio, PSVT Video and
  Signaling IP Flow) is achieved using
• Multi-Flow Packet Application (MFPA) or
  
  Enhanced Multi-Flow Packet Application (EMFPA)
• Reverse Traffic Channel MAC Subtype 3 protocol
  (RTCMAC3) on the Reverse Link
• Enhanced Forward Traffic Channel MAC Protocol on
  the Forward Link
• Physical Layer Subtype 2
• QoS aware Forward Link Scheduler
• Various attributes of the protocols are
  negotiated either using the Session Configuration
  Protocol or the Generic Attribute Update Protocol.

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What does QoS mean in 1xEV-DO Rev A Networks?

• Flows, Flows, Flows, and Queues
• To achieve 1xEV-DO Rev A air interface QoS for an
  application, the following flows are used and
  negotiated
• IP Flows are data streams generated by a user
  application (OSI) residing outside the 1xEV-DO
  Rev A protocol stack.
• RLP Flows reside at the 1xEV-DO Rev A Application
  Layer and use either Multi-Flow Packet
  Application (MFPA) or Enhanced MFPA. These flows
  are mapped to the upper layer IP flows.
• RTCMAC Flows reside at the 1xEV-DO Rev A MAC
  layer and use RTCMAC Subtype 3. These flows are
  associated to the upper layer RLP flows.
• Multiple instances (queues) of these flows
  provide QoS for concurrent applications at the
  AT, such as PSVT Audio, PSVT Video, and PSVT
  signaling.

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Multi-Flow Concept Concurrent BE and PSVT Traffic
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How is QoS requested in 1xEV-DO Rev A Networks?

• QoS in 1xEV-DO Rev A is defined and requested in
  terms of
• Flow Specification Used by the AT to state air
  interface resources required for QoS application
  (FlowProfileID)
• Interaction between AT and RAN over 1xEV-DO Rev A
  Signaling
• Filter Specification Used by the AT to define
  IP traffic flow classification and QoS treatment
  determination (Traffic Flow Template or TFT)
• Interaction between AT and PDSN as Reservation
  Resource Protocol (RSVP) over UDP Port 3455

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Successful QoS Configuration

• The conditions for QoS to be GRANTED are
• AT requests QoS (as a reservation, one per IP QoS
  Flow)
• QoS request accepted by AN with a non-NULL QoS
  response
• Requested reservation mapped to an RLP flow
• RLP to which the reservation is mapped is
  activated
• RLP flow is associated with an RTCMAC flow
• RTCMAC flow is activated
• RSVP messaging with the PDSN is successful, with
  the TFTs appropriately configured
• At this point QoS is Ready
• The AT, having determined the air interface QoS
  profile and the PDSN QoS configuration are
  complete, sends a ReservationOnRequest message
  when it desires to use the QoS

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Logical States of QoS in 1xEV-DO Rev A Networks
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• QoS Best Practices

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QoS Best Practices for 1xEV-DO Rev A Networks

• Establish ATs protocols and OSI application
  capabilities
• Understand the QoS applications needs
• Target Throughput
• Latency requirements
• Jitter
• Reliability
• Access and Paging needs
• Flow and Filter Specification
• Design for end-to-end QoS (within your control)
  for the application
• Air Interface
• Backhaul between the BTS and RNC
• Backbone network between the RNC and PDSN
• Core network controlled by the operator.

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QoS Best Practices for 1xEV-DO Rev A Networks

• End-to-end application QoS design considerations
• Coexistence with other QoS application
• Coverage
• Capacity dimensioning (access and paging load
  considerations)
• When to setup air interface QoS
• Always-On QoS application, such as VoIP
  Negotiate 1xEV-DO Rev A air interface QoS as part
  of Session Negotiation
• On-Demand QoS application, such as Video
  Streaming Negotiate 1xEV-DO Rev A air interface
  QoS only when QoS application is invoked

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QoS Best Practices for 1xEV-DO Rev A Networks

• QoS setup signaling optimizations
• Air Interface QoS signaling with RAN and RSVP
  messaging with the PDSN should happen in parallel
• Application registration (such as SIP REGISTER)
  can happen in parallel with QoS setup
• Maintain QoS setup signaling integrity
• All reservations for a single application (such
  as PSVT audio, PSVT video and signaling) should
  be bundled in a single QoS request message
• Protocol specific attributes negotiated should be
  bundled in a single bundled message
• Implement Admission Control mechanisms

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• Backup Slides

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PSVT Call Flow QoS Setup (1 of 2)
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PSVT Call Flow QoS Setup (2 of 2)
Bundled in a single message