WiMAX Network Architecture

1. WiMAX Network Architecture 潘仁義 國立中正大學通訊工程學系 jypan@ccu.edu.tw

2. Outline • WiMAX Introduction • WiMAX QoS & Flow • Network Working Group (NWG) • Network Reference Model • Network Entry • Authentication, Authorization, and Key Hierarchy • IP Configuration Setup • Mobility Management • QoS Functional Model

3. Outline WiMAX Introduction WiMAX QoS & Flow Network Working Group (NWG) Network Reference Model Network Entry Authentication, Authorization, and Key Hierarchy IP Configuration Setup Mobility Management QoS Functional Model

4. WiMAX • Worldwide Interoperability for Microwave Access • The Institute of Electrical and Electronics Engineers (IEEE) 802 committee (802.16 ). • Orthogonal Frequency Division Multiplexing (OFDM) (carriers of width of 5MHz or greater can be used ) • connectivity at speeds up to 70 Mbps • provide high speed access to about 60 businesses at T1 speeds. • can serve up to a thousand homes in term of DSL speed.

5. 802.16 History • The initial 802.16 standard in 2002, operates in the 10-to-66-GHz frequency band and requires LOS towers. • The 802.16a extension, ratified in March 2003 • allows use of 2 to 11 GHz frequency. • It boasts a 50 km range and 74.7Mbit/sec. • Data transfer rates and doesn't require LOS transmission.

6. 802.16 History • Additional 802.16 standards : • 802.16b • Quality of service • 802.16c • Interoperability, with protocols and test-suite structures • 802.16d • Fixing things not covered by 802.16c • 802.16e • Support for mobile as well as fixed broadband (802.16e-2005) • 802.16f • MIB • 802.16g • System/resource/handover Management Interoperability • 802.16j • Relay

7. Mobile WiMAX • Mobile Technical Group (MTG) in WiMAX Forum develops the system profile for Mobile WiMAX system • A Broadband wireless solution • – Fix broadband network • – Mobile broadband network • Signaling • – Orthogonal Frequency Division Multiple Access (OFDMA) • – Scalable OFDMA • Features • High Data Rate • Quality of Service • Scalability • Security • Mobility

8. WiMAX entity • Two components • Subscriber Stations (SSs) • SS typically serves a building (business or residence) • Base Station (BS) • connected to public networks • BS serves Subscriber Stations • provide SS with first-mile (or last mile) access to public networks

9. Scenario

10. Outline WiMAX Introduction WiMAX QoS & Flow Network Working Group (NWG) Network Reference Model Network Entry Authentication, Authorization, and Key Hierarchy IP Configuration Setup Mobility Management QoS Functional Model

11. Introduction • QoS supporting is a fundamental part of the WiMAX MAC-layer design. • How does WiMAX support for QoS?

12. Connections • A connection-oriented MAC architecture • all downlink and uplink connections are controlled by the serving BS • Each connection is identified by a connection identifier (CID)

13. Service flows • A service flow is a unidirectional flow of packets • with a particular set of QoS parameters • is identified by a service flow identifier (SFID) • The service flow characteristics of the connection provide the QoS for that packet

14. Comparisons of SFID & CID • Service Flow ID (SFID) does not change upon HO across BSs belonging to a single NAP • SFID shall be set just once when a layer 2 service flow is originally established, and SHALL NOT be modified by HOs. • SFID shall be assigned when a new service flow is set up and shall be maintained as the same value at the Anchor Data Path Function in spite of HOs. • Connection ID (CID) is defined as temporary in a particular cell coverage area. • CID shall be refreshed whenever MS moves into a new cell. • SFID identifies a particular Layer 2 session while CID specifies a particular logical radio link.

15. Operation Object Model

16. DSD DSC NULL DSA OPERATIONAL Service Flow Management • Dynamic Service Change (DSC) • Dynamic Service Delete (DSD) • Dynamic Service Activate (DSA)

17. Dynamic Service Flow Change

18. Classifier • A classifier is a set of matching criteria applied to each packet • It consists of some protocol-specific packet matching criteria (destination IP address, for example) • a classifier priority • a reference to a CID. • Classifiers can be added by dynamic signaling

19. QoS logical connections MS1 MAC Scheduler Service flows Classifier Service flow over QoS connections Priority queues BS MAC MS2 MAC Scheduler Associate packets into service flow Define QoS parameter for each service flow Dynamically establishing QoS-enabled service flows Associate QoS service flow with logical connections

20. Quality of Service Support

21. Scheduling services • Four services are supported in 802.16 802.16-2004 • Unsolicited Grant Service (UGS), • Real-time Polling Service (rtPS), • Non-real-time Polling Service (nrtPS), and • Best Effort (BE). • Five services are supported in 802.16e 802.16e-2005 • UGS (Unsolicited Grant Service) • RT-VR (Real-Time -Variable Rate Service) • NRT-VR (Non-Real Time -Variable Rate service) • BE (Best Efforts) • ERT-VR (Extended Real-Time Variable Rate)

22. Unsolicited Grant Service (UGS) • support real-time data streams consisting of fixed-size data packets issued at periodic intervals • Such as T1/E1 and Voice over IP without silence suppression INTERNET VoIP

23. Real-time Polling Service (rtPS) • support real-time data streams consisting of variable-sized data packets that are issued at periodic intervals • Such as moving pictures experts group (MPEG) video.

24. Non-real-time Polling Service (nrtPS) • support delay-tolerant data streams consisting of variable-sized data packets for which a minimum data rate is required • such as FTP

25. Best Effort (BE) • support data streams for which no minimum service level is required and therefore may be handled on a space-available basis.

26. Extended Real-Time Variable Rate (ERT-VR) service • support real-time applications with variable data-rates, which require guaranteed data and delay, for example VoIP with silence suppression.

27. Outline WiMAX Introduction WiMAX QoS & Flow Network Working Group (NWG) Network Reference Model Network Entry Authentication, Authorization, and Key Hierarchy IP Configuration Setup Mobility Management QoS Functional Model

28. WiMAX Forum The WiMAX Forum is a nonprofit organization formed in 2001 to enhance the compatibility and interoperability of equipment based on the IEEE 802.16 family of standards WiMAX Forum_Network Working Group (NWG) define Stage 1: Use case scenarios and service requirements and defined along with Service Provider Working Group Stage 2: Architecture Tenets, Reference Model and Reference Points Stage 3: Detailed Protocols and Procedures

29. WiMAX Working Group Application Working Group (AWG) Define applications over WiMAX that are necessary to meet core competitive offerings Certification Working Group (CWG) Handles the operational aspects of the WiMAX Forum Certified program. Evolutionary Technical Working Group (ETWG) Maintains existing OFDM profiles, develops additional fixed OFDM profiles, and develops technical specifications for the evolution of the WiMAX Forum's OFDM based networks from fixed to nomadic to portable, to mobile. Global Roaming Working Group (GRWG) Assures the availability of global roaming service for WiMAX networks in a timely manner as demanded by the marketplace. Marketing Working Group (MWG) Promotes the WiMAX Forum, its brands and the standards which form the basis for worldwide interoperability of BWA systems.

30. WiMAX Working Group Network Working Group (NWG) Creates higher level networking specifications for fixed, nomadic, portable and mobile WiMAX systems, beyond what is defined in the scope of 802.16. Regulatory Working Group (RWG) Influences worldwide regulatory agencies to promote WiMAX-friendly, globally harmonized spectrum allocations. Service Provider Working Group (SPWG) Gives service providers a platform for influencing BWA product and spectrum requirements to ensure that their individual market needs are fulfilled. Technical Working Group (TWG) The main goal of the TWG is to develop technical product specifications and certification test suites for the air interface based on the OFDMA PHY.

31. Relationship between the scopes of WiMAX NWG and 802.16 From IEEE 802.16 to WiMAX NWG build an interoperable broadband wireless network. Interoperable networks involve end-to-end service such as IP connectivity and session management, security, QoS, and mobility.

32. Tenets for WiMAX Network Systems Architecture • Based on …… • a packet-switched framework • IEEE 802.16 standard and IETF RFCs • Decoupling of access architecture from connectivity IP services • Specifying open, published and accepted standards • SHALL NOT preclude inter-technology handover • SHALL support seamless handovers at up to vehicular speeds • All-IP Network !

33. Outline WiMAX Introduction WiMAX QoS & Flow Network Working Group (NWG) Network Reference Model Network Entry Authentication, Authorization, and Key Hierarchy IP Configuration Setup Mobility Management QoS Functional Model

34. WiMAX Network Reference Model

35. Decomposed ASN into BS and ASN GW entities

36. Entities of the WiMAX Network Reference Model (1/2) ASN: Access Serving Network Logical representation of the functions of a NAP, e.g. 802.16 interface network entry and handover Radio Resource Management & Admission ctrl. L2 Session/mobility management QoS and Policy Enforcement Foreign Agent (FA) Forwarding to selected CSN

37. Entities of the WiMAX Network Reference Model (2/2) CSN: Connectivity Serving Network Logical representation of the functions of a NSP, e.g. Connectivity to the Internet, ASPs Authentication, authorization and accounting IP address management L3 Mobility and roaming between ASNs Policy & QoS management based on a SLA

38. Network Reference point (1/2) R1: Reference point between MS and BS: implements IEEE 802.16e-2005. R2: Reference point between MS and ASN-GW or CSN: logical interface used for authentication, authorization, IP host configuration and mobility management. R3: Reference point between ASN and CSN: supports AAA, policy enforcement, and mobility –management capabilities. Implements tunnel between ASN and CSN. R4: Reference point between ASN and ASN: used for MS mobility across ASNs.

39. Reference point (2/2) R5: Reference point between CSN and CSN: used for internetworking between home and visited network. R6: Reference point between BS and ASN: implements intra-ASN tunnels and used for control plane signaling. R7: Reference point between data and control plane in ASN-GW: used for coordination between data and control plane in ASN-GW. R8: Reference point between BS and BS: used for fast and seamless handover.

40. WiMAX Network Reference Model(2/2)

41. ASN Profile A Functional View

42. ASN-GW Reference model

43. Link model for Profiles A &C

44. Internetworking with 3GPP Scope WiMAX-3GPP Interworking refers to the integration of a WiMAX Access Network to an existing 3GPP core network.

45. Outline WiMAX Introduction WiMAX QoS & Flow Network Working Group (NWG) Network Reference Model Network Entry Authentication, Authorization, and Key Hierarchy IP Configuration Setup Mobility Management QoS Functional Model

46. 802.16e network entry In a WiMAX network, a full network entry includes four stages: a. Network Discovery and Selection b. Access Authentication c. IP Configuration Setup d. Data Transfer IP Configuration Setup

47. Network entry • A WiMAX subscriber station has to complete the network entry process, in order to communicate on the network. • Steps: • Scan for DL channel and establish synchronization with the BS • Obtain transmit parameters (from UCD message) • Perform initial ranging • Negotiate basic capabilities • Authorize MS and perform key exchange • Establish IP connectivity • Establish time of day • Transfer operational parameters optional • Set up connections

48. a)Downlink Channel Synchronization: When an SS wants to communicate on a WiMAX network, it first scans for available channels in the defined frequency list. On finding a DL channel, it tries to synchronize at the PHY level using the periodic frame preamble. Information on modulation and other DL and UL parameters is obtained by observing the DL Channel Descriptor (DCD) and the UL channel descriptor (UCD) of the DL channel.

49. b) Initial Ranging: • An SS starts an Initial ranging process by sending a ranging request MAC message using the minimum transmission power. If no response is received from the BS, the SS resends the message on a subsequent frame using a higher transmission power. The response either indicates power and timing corrections that the SS must make or indicates success. • Purpose: • The process by which the SS and BS maintain the quality of RF communication link between them. • When ranging finished, the BS would allocate Basic CID and Primary management CID to SS

50. c) Exchanging Capabilities: After successful completion of the initial ranging step, the SS sends capability request message indicating the supported modulation level, coding scheme and rates and duplexing methods. The MS and ASN also SHALL negotiate the PKM version, PKMv2 security capabilities and authorization policy including requirements and support for Device Authentication.