Wi. MAX Network Architecture 潘仁義 國立中正大學通訊 程學系 jypan@ccu. edu. tw
Outline l l l l l Wi. MAX Introduction Wi. MAX Qo. S & Flow Network Working Group (NWG) Network Reference Model Network Entry Authentication, Authorization, and Key Hierarchy IP Configuration Setup Mobility Management Qo. S Functional Model
Outline l l l l l Wi. MAX Introduction Wi. MAX Qo. S & Flow Network Working Group (NWG) Network Reference Model Network Entry Authentication, Authorization, and Key Hierarchy IP Configuration Setup Mobility Management Qo. S Functional Model
Wi. MAX l l l 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 5 MHz or greater can be used ) connectivity at speeds up to 70 Mbps provide high speed access to about 60 businesses at T 1 speeds. can serve up to a thousand homes in term of DSL speed.
802. 16 History l l The initial 802. 16 standard in 2002, operates in the 10 -to-66 -GHz frequency band requires LOS towers. The 802. 16 a extension, ratified in March 2003 l l l allows use of 2 to 11 GHz frequency. It boasts a 50 km range and 74. 7 Mbit/sec. Data transfer rates and doesn't require LOS transmission.
802. 16 History l Additional 802. 16 standards : l 802. 16 b l l l Interoperability, with protocols and test-suite structures l l Fixing things not covered by 802. 16 c MIB 802. 16 g l l Support for mobile as well as fixed broadband (802. 16 e-2005) 802. 16 f l 802. 16 d l 802. 16 e l Quality of service 802. 16 c l l System/resource/handov er Management Interoperability 802. 16 j l Relay
Mobile Wi. MAX l Mobile Technical Group (MTG) in Wi. MAX Forum develops the system profile for Mobile Wi. MAX system l A Broadband wireless solution l – Fix broadband network l – Mobile broadband network Signaling l – Orthogonal Frequency Division Multiple Access (OFDMA) l – Scalable OFDMA Features l High Data Rate l Quality of Service l Scalability l Security l Mobility l l
Wi. MAX entity l Two components l Subscriber Stations (SSs) l l SS typically serves a building (business or residence) Base Station (BS) l l l connected to public networks BS serves Subscriber Stations provide SS with first-mile (or last mile) access to public networks
Scenario
Outline l l l l l Wi. MAX Introduction Wi. MAX Qo. S & Flow Network Working Group (NWG) Network Reference Model Network Entry Authentication, Authorization, and Key Hierarchy IP Configuration Setup Mobility Management Qo. S Functional Model
Introduction l Qo. S supporting is a fundamental part of the Wi. MAX MAC-layer design. l How does Wi. MAX support for Qo. S?
Connections l A connection-oriented MAC architecture l l all downlink and uplink connections are controlled by the serving BS Each connection is identified by a connection identifier (CID)
Service flows l A service flow is a unidirectional flow of packets l l l with a particular set of Qo. S parameters is identified by a service flow identifier (SFID) The service flow characteristics of the connection provide the Qo. S for that packet
Comparisons of SFID & CID l l l Service Flow ID (SFID) does not change upon HO across BSs belonging to a single NAP l SFID shall be set just once when a layer 2 service flow is originally established, and SHALL NOT be modified by HOs. l 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. l 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.
Operation Object Model
Service Flow Management l l l Dynamic Service Change (DSC) Dynamic Service Delete (DSD) Dynamic Service Activate (DSA) DSD DSC NULL DSA OPERATIONAL
Dynamic Service Flow Change
Classifier l A classifier is a set of matching criteria applied to each packet l l 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
Scheduler Service Classifier flows Scheduler Qo. S logical connections MS 1 MAC Service flow over Qo. S connections BS MAC Priority queues MS 2 MAC Associate packets into service flow Define Qo. S parameter for each service flow Dynamically establishing Qo. S-enabled service flows Associate Qo. S service flow with logical connections
Quality of Service Support
Scheduling services l Four services are supported in 802. 16 -2004 l l l Unsolicited Grant Service (UGS), Real-time Polling Service (rt. PS), Non-real-time Polling Service (nrt. PS), and Best Effort (BE). Five services are supported in 802. 16 e 2005 l l l 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)
Unsolicited Grant Service (UGS) l support real-time data streams consisting of fixed-size data packets issued at periodic intervals l Such as T 1/E 1 and Voice over IP without silence suppression INTERNET Vo. IP
Real-time Polling Service (rt. PS) l support real-time data streams consisting of variable-sized data packets that are issued at periodic intervals l Such as moving pictures experts group (MPEG) video.
Non-real-time Polling Service (nrt. PS) l support delay-tolerant data streams consisting of variable-sized data packets for which a minimum data rate is required l such as FTP
Best Effort (BE) l support data streams for which no minimum service level is required and therefore may be handled on a space-available basis.
Extended Real-Time Variable Rate (ERT-VR) service l support real-time applications with variable data-rates, which require guaranteed data and delay, for example Vo. IP with silence suppression.
Outline l l l l l Wi. MAX Introduction Wi. MAX Qo. S & Flow Network Working Group (NWG) Network Reference Model Network Entry Authentication, Authorization, and Key Hierarchy IP Configuration Setup Mobility Management Qo. S Functional Model
Wi. MAX Forum l l The Wi. MAX 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 Wi. MAX Forum_Network Working Group (NWG) define l l l 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
Wi. MAX Working Group l Application Working Group (AWG) l l Certification Working Group (CWG) l l Maintains existing OFDM profiles, develops additional fixed OFDM profiles, and develops technical specifications for the evolution of the Wi. MAX Forum's OFDM based networks from fixed to nomadic to portable, to mobile. Global Roaming Working Group (GRWG) l l Handles the operational aspects of the Wi. MAX Forum Certified program. Evolutionary Technical Working Group (ETWG) l l Define applications over Wi. MAX that are necessary to meet core competitive offerings Assures the availability of global roaming service for Wi. MAX networks in a timely manner as demanded by the marketplace. Marketing Working Group (MWG) l Promotes the Wi. MAX Forum, its brands and the standards which form the basis for worldwide interoperability of BWA systems.
Wi. MAX Working Group l Network Working Group (NWG) l l Regulatory Working Group (RWG) l l Influences worldwide regulatory agencies to promote Wi. MAX-friendly, globally harmonized spectrum allocations. Service Provider Working Group (SPWG) l l Creates higher level networking specifications for fixed, nomadic, portable and mobile Wi. MAX systems, beyond what is defined in the scope of 802. 16. 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) l 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.
Relationship between the scopes of Wi. MAX NWG and 802. 16 l From IEEE 802. 16 to Wi. MAX NWG l l build an interoperable broadband wireless network. Interoperable networks involve end-to-end service l such as IP connectivity and session management, security, Qo. S, and mobility.
Tenets for Wi. MAX Network Systems Architecture l Based on …… l l l l 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 !
Outline l l l l l Wi. MAX Introduction Wi. MAX Qo. S & Flow Network Working Group (NWG) Network Reference Model Network Entry Authentication, Authorization, and Key Hierarchy IP Configuration Setup Mobility Management Qo. S Functional Model
Wi. MAX Network Reference Model
Decomposed ASN into BS and ASN GW entities
Entities of the Wi. MAX Network Reference Model (1/2) l ASN: Access Serving Network l Logical representation of the functions of a NAP, e. g. § § § 802. 16 interface network entry and handover Radio Resource Management & Admission ctrl. L 2 Session/mobility management Qo. S and Policy Enforcement Foreign Agent (FA) Forwarding to selected CSN
Entities of the Wi. MAX Network Reference Model (2/2) l CSN: Connectivity Serving Network l Logical representation of the functions of a NSP, e. g. § § § Connectivity to the Internet, ASPs Authentication, authorization and accounting IP address management L 3 Mobility and roaming between ASNs Policy & Qo. S management based on a SLA
Network Reference point (1/2) l R 1: l l R 2: l l Reference point between MS and ASN-GW or CSN: logical interface used for authentication, authorization, IP host configuration and mobility management. R 3: l l Reference point between MS and BS: implements IEEE 802. 16 e-2005. Reference point between ASN and CSN: supports AAA, policy enforcement, and mobility –management capabilities. Implements tunnel between ASN and CSN. R 4: l Reference point between ASN and ASN: used for MS mobility across ASNs.
Reference point (2/2) l R 5: l l R 6: l l Reference point between BS and ASN: implements intra. ASN tunnels and used for control plane signaling. R 7: l l Reference point between CSN and CSN: used for internetworking between home and visited network. Reference point between data and control plane in ASNGW: used for coordination between data and control plane in ASN-GW. R 8: l Reference point between BS and BS: used for fast and seamless handover.
Wi. MAX Network Reference Model(2/2)
ASN Profile A Functional View
ASN-GW Reference model
Link model for Profiles A &C
Internetworking with 3 GPP Scope l Wi. MAX-3 GPP Interworking refers to the integration of a Wi. MAX Access Network to an existing 3 GPP core network.
Outline l l l l l Wi. MAX Introduction Wi. MAX Qo. S & Flow Network Working Group (NWG) Network Reference Model Network Entry Authentication, Authorization, and Key Hierarchy IP Configuration Setup Mobility Management Qo. S Functional Model
802. 16 e network entry l In a Wi. MAX 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
Network entry l l A Wi. MAX subscriber station has to complete the network entry process, in order to communicate on the network. Steps: l l l l l 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
l l a)Downlink Channel Synchronization: When an SS wants to communicate on a Wi. MAX 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.
l l l 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: l l 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
l l l 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, PKMv 2 security capabilities and authorization policy including requirements and support for Device Authentication.
l l d) Authentication: After capability negotiation, the BS authenticates the SS, determines the ciphering algorithm to be used, and sends an authentication response to the SS. e) Registration: After authentication, the SS sends a registration request message to the BS and the BS sends a registration response, with a secondary management CID for IP configuration
l l f) IP Connectivity: After registration, the SS gets the IP address via DHCP. The SS also downloads other operational parameters using TFTP. l g) Connection Creation: l After completing the IP connectivity step, transport connections are created. For preprovisioned service flows, the BS sends a dynamic service flow addition request message to the SS and SS confirms the creation of connection. For non-preprovisioned service flows, connection creation is initiated by the SS by sending a dynamic service flow addition request message to the BS. The BS responds with the confirmation.
Network Discovery and Selection l l NAP discovery NSP Access discovery NSP Enumeration and selection ASN attachment based on NSP Selection
NAP and NSP Discovery “ 1” to indicate one or more NSPs • As per “ 6. 3. 2. 3. 63 Service Identity Information (SII-ADV) message”, a BS may use the SII-ADV message to broadcast a list of Network Service Provider (NSP) Identifiers. • The MS MAY include the Visited NSP ID TLV in the SBC-REQ message to solicit BS transmittal of the Visited NSP Realm TLV in the SBC-RSP message.
ASN Attachment based on NSP Selection MS_1@NSP_1. com NSP_4!MS_2@NSP_1. com
Outline l l l l l Wi. MAX Introduction Wi. MAX Qo. S & Flow Network Working Group (NWG) Network Reference Model Network Entry Authentication, Authorization, and Key Hierarchy IP Configuration Setup Mobility Management Qo. S Functional Model
Why encryption? l Encryption l a mechanism that protects data confidentiality and integrity l plaintext to ciphertext
Encryption • Encryption is always applied to the MAC PDU payload; the generic MAC header is not encrypted; some management messages are not encrypted.
Encryption -- Wi. MAX l l Wi. MAX uses the Advanced Encryption Standard (AES) to produce ciphertext. Receiver of the ciphertext simply reverses the process to recover the plaintext.
Public key infrastructure l l l The Wi. MAX 802. 16 e-2005 standard uses the Privacy and Key Management Protocol version 2 (PKMv 2) for securely transferring keying material between the base station and the mobile station. PKMv 2’s components l X. 509 digital certificates l RSA public-key algorithm l Strong encryption algorithm to perform key exchanges between SS to BS. PKMv 2 mechanism l Validates user identity and establishes an authorization key (AK) l AK is used to derive the encryption keys, e. g. KEK, CMAC_KEY l Supports device and user authentication between MS and home CSN (PKMv 1 only for device)
Public key infrastructure l PKMv 2 supports the use of the Rivest-Shamir-Adlerman (RSA) public key cryptography exchange. l RSA public key exchange l requires that the mobile station establish identity using either a manufacturer-issued X. 509 digital certificate (Device Credential, called Device-Cert) or an operator-issued credential such as a subscriber identity module (SIM) card (Subscriber Credential, called Subscriber Root Key, SUBC). l X. 509 digital certificate contains the mobile station's Public-Key (PK) and its MAC address.
X. 509 加密資料 (public key) 解密資料 (private key)
Authentication, Authorization and Accounting l The Wi. MAX AAA framework is based on IETF specifications. The term AAA is used to refer to the AAA protocols, Radius or Diameter. l The AAA framework provides the following services to Wi. MAX: l Authentication Services l l Authorization Services l l These include MS, user, or combined MS and user authentication. These include the delivery of information to configure the session for access, mobility, Qo. S and other applications. Accounting Services l These include the delivery of information for the purpose of billing (both prepaid and post paid billing) and information that can be used to audit session activity by both the home NSP and visited NSP.
ASN security architecture (1/2) l The mobile station transfers the X. 509 digital certificate to the Wi. MAX network, which then forwards the certificate to a certificate authority. The certificate authority validates the certificate, thus validating the user identity.
ASN security architecture (2/2)
User/Device Authentication Protocol layering
Keys in 802. 16 PKMv 2 l Master Session Key (MSK) l l l Pairwise Master Key (PMK) l l l Traffic Encryption Key (TEK) l l distributed by the BS refreshed periodically encrypted by KEK Traffic is encrypted / decrypted by TEK issued by operator Extended Master Session Key (EMSK) l l issued by manufacturer Subscriber credential l 160 bits, derived from PMK(1+2), SS MAC, BS ID 128 bits, derived from AK, SS MAC, BS ID Device credential l Key Encryption Key (KEK) l l 160 bits, derived from MSK Known by authenticator and AAA peer l Authorization Key (AK) l l 512 bits, generated in EAP process Known by AAA peer, AAA server, and authenticator 512 bits, generated in EAP known by AAA peer and server for generating Mobile IP Root Key in CSN CMAC_*KEY_* l l 128 bits, derived from AK, SS MAC, BS ID For Message Integrity Check
Wi. MAX Key Hierarchy and Distribution for ASN for CSN
PKMv 2 Procedures Link activation triggers EAP Routing based on NAI realm PKMv 2 three-way handshake for mutual authentication CMAC for MAC management messages protection KEK for encryption of TEK
Pairwise Key Management
Outline l l l l l Wi. MAX Introduction Wi. MAX Qo. S & Flow Network Working Group (NWG) Network Reference Model Network Entry Authentication, Authorization, and Key Hierarchy IP Configuration Setup Mobility Management Qo. S Functional Model
IP Configuration Setup l Point of Attachment (Po. A) address l l l Fixed and nomadic access scenarios l l has to be routable in the CSN and ASN, and SHALL be assigned from the CSN address space For portable and mobile access, the Po. A SHALL be assigned from either Home NSP or Visited NSP, corresponding to the Home address (Ho. A) DHCP Mobile access scenarios l PMIP 4 / CMIP 4 / PMIP 6 / CMIP 6
H-AAA HA
IP Configuration Setup Procedure (Proxy Mobile IP)
Proxy Mobile IP
IP Configuration Setup Procedure (Client Mobile IPv 4, CMIPv 4 )
Mobile IPv 4 (MIP) Binding Update Data Transmission Corresponded Node (CN) Foreign Agent (FA) Home Agent (HA) Mobile Node (MN) Home Network Foreign Network
IP Configuration Setup Procedure (Client Mobile IPv 6 , CMIP 6 )
Outline l l l l l Wi. MAX Introduction Wi. MAX Qo. S & Flow Network Working Group (NWG) Network Reference Model Network Entry Authentication, Authorization, and Key Hierarchy IP Configuration Setup Mobility Management Qo. S Functional Model
Mobility Management l MAC layer handover procedures l l Intra-ASN mobility l l Handoff process Three levels of association Two optional modes of HO decision and initiation ASN Anchored Mobility inter-ASN mobility l l ASN Anchored Mobility (Profile A & C) CSN Anchored Mobility
Mobility scenario
Stages of Handoff Process l Cell reselection l l HO Decision and Initiation l l A handover begins with a decision for an MS to handover from a serving BS to a target BS. The decision may originate either at the MS, the serving BS, or on the network. Termination with the Serving BS l l MS may use Neighbor BS information in MOB_NBR-ADV or scan Neighbor BS for handing over to potential target BS. After the handover request/response handshake has completed, the MS may begin the actual HO. During the HO process, the MS terminates service with the serving BS by sending a MOB_HO-IND message. Network entry/re-entry
Three levels of association l Association l an optional initial ranging procedure in scanning interval l enables the MS to acquire service information for proper selection of HO target and/or expediting a potential future handover to a target BS. l Level 0: Scan / Association without coordination l l Level 1: Association with coordination l l The Serving BS allocates periodic intervals where the MS may range neighboring BSs; the Target BS provides only contention-based ranging allocations. The Serving BS coordinates association between the MS and neighboring BSs, with unique code and transmission opportunity to prevent collision. Level 2: Network assisted association reporting l The MS is required only to transmit the CDMA ranging code at the neighbor BS. The Serving BS may aggregate all ranging related information (e. g. PHY offsets and CIDs from BSs) into a single MOB_ASC_REPORT message.
Two optional modes of HO decision and initiation l Diversity Set l l Macro Diversity Handover (MDHO) l l A list of BSs that are involved in handoff process with MS MS may transmit to and receive from BSs in Diversity Set at the same time Fast BS Switching (FBSS) l l l An Anchor BS is defined among the BSs in Diversity Set MS only communicates with the Anchor BS for UL and DL messages including management and traffic connections. Transition from one Anchor BS to another (“switching”) in Diversity Set is performed without invocating HO procedure
Two Mobility Levels in Wi. MAX l ASN anchored mobility or micro mobility l The MS moves between Data Path Functions while maintaining the same anchor FA sitting at the northbound edge of the ASN network l The data flow between CSN and Data Path Functions pivots at the anchor FA. l CSN is unaware of any mobility that occurs between ASN Data Plane Functions l CSN Anchored Mobility Management or macro mobility l The MS changes to a new anchor FA l The new FA and CSN exchange signaling messages to establish data forwarding path
ASN Anchored Mobility Management(1/3) l ASN Anchored Mobility Management is defined as mobility of an MS not involving a Co. A update (MIP re-registration)
ASN anchor Mobility (2/3)
ASN anchored mobility (3/3)
CSN Anchored mobility l For CSN Anchored Mobility Management two variants of the MIP protocols are supported: l l Client MIP (CMIP) l CMIP is an IETF compliant MIP solution based on a Mobile IP enabled MS. l CSN Anchored Mobility Management will cover CMIP based mobility schemes for IPv 4 and IPv 6. Proxy MIP (PMIP) l Proxy MIP is an embodiment of the standard Mobile IP framework in which an MN is transparently instanced in the access network on behalf of a client that is not MIP-aware or MIP-capable.
CSN Anchor mobility ( R 3 -mobility ) l Re-anchoring of the current FA to a new FA and the consequent binding updates to update the upstream and downstream data forwarding paths.
CSN to ASN Anchored Mobility Management Relationship (1/2)
CSN to ASN Anchored Mobility Management Relationship (2/2)
Outline l l l l l Wi. MAX Introduction Wi. MAX Qo. S & Flow Network Working Group (NWG) Network Reference Model Network Entry Authentication, Authorization, and Key Hierarchy IP Configuration Setup Mobility Management Qo. S Functional Model
Qo. S Functional Elements l l l Service Flow Management (SFM) l responsible for the creation, admission, activation, modification and deletion of 802. 16 service flows. Service Flow Authorization (SFA) l Evaluate any service request against user Qo. S profile. AF: Application Function l e. g. , SIP Proxy PF: Policy Function l Maintained information includes H-NSP's general policy rules LPF: Local Policy Function l enforce admission control based on available resources
Pre-provisioned service flow
References l Applications for 802. 16 -2004 and 802. 16 e Wi. MAX Networks, Wi. MAX Forum. l Air Interface for Fixed Broadband Wireless Access Systems, IEEE Standard. (IEEE 802. 16 -2004) l Air Interface for Fixed and Mobile Broadband Wireless Access Systems, IEEE Standard. (IEEE 802. 16 e-2005) l Wimax forum Wi. MAX End-to-End Network Systems Architecture (Stage 2), Release 1, Version 1. 3. 0, September 21, 2008 l Wimax forum Wi. MAX End-to-End Network Systems Architecture (Stage 3: Detailed Protocols and Procedures), Release 1, Version 1. 3. 0 September 21, 2008
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