End-to-End QoS in LTE
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The document provides insights into end-to-end Quality of Service (QoS) in LTE networks, discussing the necessity and mechanisms of QoS management to enhance customer experience. Key topics include market dynamics, policy enforcement, and the architecture underpinning policy and charging control in LTE systems, which are vital for managing network traffic amidst increasing demand. The presentation concludes with the benefits and challenges of implementing QoS in LTE and emphasizes the opportunities it presents for service providers.
![Traffic Management Key Features
Network processors can be used to add a number of
Traffic Management (TM) capabilities to a DPI blade:
• Egress traffic shaping with 256k queues and 5 levels of hierarchy
• Ingress packet filtering and denial-of-service prevention
• Flow-based load balancing across associated processors
• IP Defragmentation and packet reassembly
An NPU is designed to maintain the huge array of per-
Class of Service (CoS) queue counters and timers
required to provided fine-grained scheduling
• Weighted Round Robin (WRR)
• Deficit [Weighted] Round Robin (DRR / DWRR)
• Weighted Random Early Detection (WRED)
• Committed Information Rate / Committed Burst Size (CIR / CBS)
Radisys Corporation Confidential 31](https://image.slidesharecdn.com/2012ltewebinarseriespart4-lteqoswebinar-120713171709-phpapp02/85/End-to-End-QoS-in-LTE-31-320.jpg)
End-to-End QoS in LTE
- 1. Welcome! Real Implementation Challenges of LTE Network Equipment: April 12 Exploring the Trade-offs and Deploying LTE Small Cells: Interference Solutions Mitigation Solutions May 17 Building EPC Systems June 14 The LTE Service Layer July 12 End-to-End QoS in LTE To view past webinars: http://www.radisys.com/recent-webinars/ Radisys Corporation Confidential 1
- 2. End-to-End QoS in LTE Delivering the Appropriate Customer Experience Speakers: Larry Greenstein – Sr. Product Line Manager Dikshit Sawhney – Software Architect James Radley – Sr. Architect July 12, 2012 Radisys Corporation Confidential 2
- 3. Today’s Agenda Market Dynamics LTE QoS Fundamentals LTE QoS Methods and Mechanisms Policy Enforcement Conclusion Q&A / Wrap-up Radisys Corporation Confidential 3
- 4. End-to-End LTE Infrastructure From Radio Access to Media Processing Radio Access Network Evolved Packet Core Policy Control IMS IP Policy & User Mobility Multimedia Equipment Charging Management Subsystem Routing Home eNodeB Entity Function Application Media Server Resource Function User Policy & Equipment Charging Internet Enforcement Function eNodeB LTE Security Serving Packet Gateway Gateway Gateway Macro Small Cells 10G 40G ATCA Dumb Smart Pipes Audio Video Conf 60+ Customer Wins ~40% ATCA Market Share Traffic Management ~65% Market Share Radisys Corporation Confidential 4
- 5. Usage Up, Revenue Down QoS to the Rescue Capacity Mind The Gap Revenue vs. Traffic Growth Traffic Revenues & Traffic Gap Widening Voice Era Revenues Data Era Traffic Doubling every 12 months Must Increase ARPU VideoTextOperators’ Albatross = Must Lower Cost per Bit Source: Cisco VNI Source: Heavy Reading Radisys Corporation Confidential 5
- 6. Today’s Agenda Market Dynamics LTE QoS Fundamentals LTE QoS Methods and Mechanisms Policy Enforcement Conclusion Q&A / Wrap-up Radisys Corporation Confidential 6
- 7. LTE QoS: Fundamental Need Why QoS? • Finite network resources – Radio spectrum limited – Backhaul bandwidth limited – Network congestion has to be managed • Users (applications) need a variety of services – Guaranteed bit rate (voice) – High speed throughput (video) – Priority service (emergency call) Radisys Corporation Confidential 7
- 8. Policy Control and Charging (PCC) Policy Management • Operator control over network usage • Control the level of service provided and charge accordingly – Superior performance for the customers that pay for it – Enforce limits or restrictions based on customer subscription – Dynamic service level adjustment enhances QoE – Offer attractive options to gain market share – Restrict content based on subscription or local laws Radisys Corporation Confidential 8
- 9. Where QoS Happens in the Network Home AF IMS Subscriber Application Server Function Network Policy & Mobility Charging Management Rules Entity Function Internet eNodeB Serving PDN Policy & Charging UE Gateway Gateway Enforcement Function Web Radio S1 S5 Email Bearer Bearer Bearer Service Data Flows Voice Packet Filters Radisys Corporation Confidential 9
- 10. Poll Question 1 The top QoS concern of operators and equipment manufacturers is: A. Adding value and monetizing it (increase revenue) B. Efficient use of network resources (reduce cost) C. Ensuring customer satisfaction D. Compliance with regulations Radisys Corporation Confidential 10
- 11. Today’s Agenda Market Dynamics LTE QoS Fundamentals LTE QoS Methods and Mechanisms Policy Enforcement Conclusion Q&A / Wrap-up Radisys Corporation Confidential 11
- 12. Agenda – QoS Specifics QoS Functions in Control & User Plane Policy & Charging Control Architecture EPS Bearers and Service Data Flows QoS Attributes Example PCC Call Flow Radisys Corporation Confidential 12
- 13. QoS Functions Control Plane • Admission control maintains information about all available resources of a network entity and takes decision to allow a new session or not based on the current resource usage. • Subscription Control checks whether or not a user is entitled to use the requested service with the specified QoS attributes • Service Management coordinates the functions of the control plane entities during setup, modification and deletion of the EPS bearers • Translation function converts between the EPC QoS parameters the various protocols for service control of interfacing external networks e.g., UMTS to IP QoS parameters mapping Radisys Corporation Confidential 13
- 14. QoS Functions User Plane • Mapping function provides each data unit with the specific marking required to receive the intended QoS at the transfer by a bearer service, e.g., DSCP marking at the PDN-GW • Classification function assigns data units to the established services of a user according to the related QoS attributes if the user has multiple bearer services established • Resource Manager distributes the available resources between all services sharing the same resource based on the QoS, e.g., scheduling, bandwidth management, and power control for the radio bearers • Traffic Shaping provides conformance between the negotiated QoS for a service and the arriving data traffic Radisys Corporation Confidential 14
- 15. QoS Functions in different Network Elements TE MT RAN CN EDGE Gateway Ext. Netwk. Class. Class. Cond. Cond. Cond. Mapping Mapping Mapping Resource Resource Resource Resource Resource Local BS External BS Manager Manager Manager Manager Manager RAN Access Network RAN phys. BS BB network service Service Radisys Corporation Confidential 15
- 16. Policy and Charging Control (PCC) Architecture Subscription Profile AF Repository (SPR) Online Sp Rx Charging System (OCS) Policy and Charging Rules Function (PCRF) Gxx Gx BBERF PCEF Gy Gz Offline Charging System Gateway (OFCS) Radisys Corporation Confidential 16
- 17. PCC Network Elements PCRF (Policy & Charging Rules Function) • PCRF is the central node in the policy and charging control architecture; it keeps a DB of PCC rules in SPR and supports flow-based charging and policy (QoS) • Interworks with other network elements via the Diameter protocol SPR (Subscription Profiles Repository) • DB of PCC rules; can be co-located with HSS or PCRF • A PCC rule consists of traffic filters to map Service Data Flows (SDF) to EPS Bearers, QoS and charging related parameters PCEF (Policy & Charging Enforcement Function) • The enforcement part of the policy architecture • Main functions include DPI, traffic shaping, etc. • Typically co-located with a PDN-GW BBERF (Bearer Binding and Event Reporting Function) • Bearer Binding and Event Reporting Function • Use PCC rules to map SDFs to EPS bearers; logical function of PDN-GW Radisys Corporation Confidential 17
- 18. Relationship between SDF Flows and EPS Bearers QoS is defined on a per EPS Bearer basis • An EPS bearer is an end-to-end connection between the service user and PDN-GW. It consists of EPC Bearer, S1 Bearer and Radio Bearer • Service data flows sharing the same QoS/IP address use the same EPS bearer. Examples of SDFs include FTP, HTTP, VoIP IMS traffic etc. • Traffic filters at UE and PDN-GW determine which traffic flow gets mapped to which EPS Bearer Radisys Corporation Confidential 18
- 19. EPS Bearers GBR vs. Non-GBR Bearers • GBR require resources to be reserved in every node in the EPS through which data packet traverses; requires efficient admission control methods • Non-GBR specifies best-effort service – useful for background, interactive traffic classes such as email, web browsing, file download, etc. Dedicated vs. Default Bearers • Default bearer (one per UE IP) setup on Attach provides basic connectivity – best effort QoS, non-GBR • One or more Dedicated bearers setup for specific QoS requirements – can be GBR or non-GBR Radisys Corporation Confidential 19
- 20. QoS Attributes Maximum bit rate (MBR, AMBR) • Maximum allowable bit rate for a GBR bearer or Aggregate Maximum bit rate for all non-GBR bearers combined • AMBR defined on per APN and per subscriber basis Guaranteed bit rate (GBR) • Guaranteed by the network via Admission Control • Can’t exceed MBR in Release 8 Radisys Corporation Confidential 20
- 21. QoS Attributes, continued QoS Class Identifier (QCI) • Defines packet forwarding treatment at each node, e.g., queuing thresholds, scheduling weight, admission control priority, etc. • Nine standardized QCI values with different characteristics – GBR/non-GBR, priority, delay sensitivity, and packet error loss rate e.g., QCI 1 is defined for a GBR bearer for conversational or voice traffic Allocation and Retention Priority (ARP) • “Allocation” dictates control plane behavior during bearer setup, modification procedures, etc. • “Retention” determines relative priority of a bearer over other bearers in case of congestion • Fifteen different ARP (priority) levels – 1 being the highest priority Radisys Corporation Confidential 21
- 22. Call Flow - PCRF Interaction During Dedicated Bearer Setup UE eNodeB MME Serving GW PDN GW PCRF (A) 1. IP-CAN Session Modification 2. Create Bearer Request 3. Create Bearer Request 4. Bearer Setup Request / Session Management Request 5. RRC Connection Reconfiguration 6. RRC Connection Reconfiguration Complete 7. Bearer Setup Response 8. Direct Transfer 9. Session Management Response 10. Create Bearer Response 11. Create Bearer Response 12. IP-CAN Session Modification (B) Radisys Corporation Confidential 22
- 23. Today’s Agenda Market Dynamics LTE QoS Fundamentals LTE QoS Methods and Mechanisms Policy Enforcement Conclusion Q&A / Wrap-up Radisys Corporation Confidential 23
- 24. PCEF and DPI The Policy & Charging Enforcement Function (PCEF) cannot rely on coarse-grained assumptions about flow types • Subscriber to be identified and associated policy profile retrieved • DPI of multiple initial packets in every new stream required to correctly determine service signature • Fragmented packets may need to be temporarily reassembled for analysis before forwarding on in original pieces. Policy engines need to be tailored to the unique requirements for the confluence or regional usage patterns and characteristics of installed network • Enforce only those policies which matter and with no more precision than necessary Radisys Corporation Confidential 24
- 25. User Specified Profiles The win-win cost / benefit advantage of user-elected usage profiles make this a compelling technology My ideal profile may not be yours, e.g.: • On-time delivery of VoIP packets above all else • Anything over VPN should get preference over everything below • Favor web browsing traffic – But no need to hurry advertisements • Don’t prejudice email traffic unless you must • Feel free to throttle video (I don’t care) – unless I’m on Wi-Fi • Please block software updates when I am roaming – Particularly difficult: how does an operator export preference profiles? Radisys Corporation Confidential 25
- 26. Typical Flow Management Architecture Stage 1 Stage 2 Stage 3 Flow De-tunnel Extract flow ID Table Stage 4 Known Flow Apply Rule Update flow table Application processing ~ 90% of packets - Load Balance Stage 5 - Rate shaping - Monitoring / Analysis Unknown Classification Engine - Video conversion - Policy enforcement Low level Update flow table ~ 10% of packets Stage 6 Custom Assign new flow to appropriate target appln resource Stateful, application aware, load balancer is key for traffic steering applications Radisys Corporation Confidential 26
- 27. Packet Flow Analysis New packets arriving enable additional detail to be extracted from flow …approx 10% packets HTTP GMAIL Metadata …Username …Email title Server Load …Content API State Machine User Application Add new entry by default… Application adds …or wait for application Buffered table entry & rule API Packets Apply Rule e.g. put into correct priority queue Radisys Corporation Confidential 27
- 28. Possible Mapping of LTE QCI: Single Subscriber Priority 1 QC5 Signaling Commit WFQ Flow Shaper Priority 2 CIR QC1 Commit/Excess/Red Voice <Commit Flow Shaper Green QC2 Commit/Excess/Red Video Strict Priority Priority Mapper Class Shaper Flow Shaper Excess QC3 WFQ Commit/Excess/Red Priority 4 CIR Video <Excess Yellow Flow Shaper QC4 Commit/Excess/Red Gaming >Excess QC6 Red Gaming Non-CIR QC7 Video Priority 3 WFQ QC8 TCP Radisys Corporation Confidential 28
- 29. Example: Traffic Management Assist NPU mezzanine provides 80Gbps NPU for PP81 to accelerate blade performance Broad potential applications • Load Balancing • Ingress Traffic Management • Egress Traffic Management • IP Defragmentation • Packet Normalization • Statistics Acceleration Efficient Software Interface for low overhead on XLP Radisys Corporation Confidential 29
- 30. Traffic Management Connectivity 4 DIMM PCIe x8 XLP832 RTM PCIe x8 / ILA ICI TM Mezzanine Up to 120Gbps XLP832 4x10G 120G PCIe x1 4 DIMM 4x10G Fabric Buffer Memory 200G Fabric TM Unit Broadcom Up to 5 ports Stats Trident switch Memory 8 x10G 5 x 40G (fabric ch0-4) TM connects into main Ethernet switch to allow for flexible packet routing configurations TM managed over PCIe by XLP Radisys Corporation Confidential 30
- 31. Traffic Management Key Features Network processors can be used to add a number of Traffic Management (TM) capabilities to a DPI blade: • Egress traffic shaping with 256k queues and 5 levels of hierarchy • Ingress packet filtering and denial-of-service prevention • Flow-based load balancing across associated processors • IP Defragmentation and packet reassembly An NPU is designed to maintain the huge array of per- Class of Service (CoS) queue counters and timers required to provided fine-grained scheduling • Weighted Round Robin (WRR) • Deficit [Weighted] Round Robin (DRR / DWRR) • Weighted Random Early Detection (WRED) • Committed Information Rate / Committed Burst Size (CIR / CBS) Radisys Corporation Confidential 31
- 32. Poll Question 2 To adequately classify an LTE GTP-U packet stream for QoS purposes, what degree of analysis is required? A. QoS can be defined with a straight mapping based upon assigned Tunnel Endpoint IDentifer (TEID) B. Simple mapping from tunneled L3/L4 attributes (L4 port number, DiffServ, Subscriber’s IP address, etc) C. Parsing initial packets with a limited set of decision tree rules to differentiate broad class of service (e-mail, video, http, etc.) D. Signature analysis on early packets until a precise recognition is made E. Ongoing signature analysis in case the nature of the flow changes F. Can’t do any useful DPI because packets are encrypted Radisys Corporation Confidential 32
- 33. Today’s Agenda Market Dynamics LTE QoS Fundamentals LTE QoS Methods and Mechanisms Policy Enforcement Conclusion Q&A / Wrap-up Radisys Corporation Confidential 33
- 34. Conclusions LTE QoS Benefits • User: Assures service delivery meets expectations • Operator: Can offer a wide variety of services and monetize them Embedded LTE QoS Challenges Wireless • Requires coordination across all Infrastructure business units to plan and execute Solutions LTE QoS Opportunities • LTE presents a tremendous Unmatched opportunity for mobile services to Products & grow faster than at any time in the Expertise past Radisys Corporation Confidential 34
- 35. Today’s Agenda Market Dynamics LTE QoS Fundamentals LTE QoS Methods and Mechanisms Policy Enforcement Conclusion Q&A / Wrap-up Radisys Corporation Confidential 35
- 36. Q&A Contact us! Larry: larry.greenstein@radisys.com DS: dikshit.sawhney@radisys.com James: james.radley@radisys.com For more information on our products, visit: www.radisys.com ̴ Please fill out our short survey ̴ Enter in your mailing address to receive a Free Trillium Poster! THANK YOU FOR ATTENDING! Radisys Corporation Confidential 36