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Tor K Moseng, Handoff in Wireless Internet Access

Trial Lecture Vertical and Horizontal Handoff in Wireless Internet Access. Tor K Moseng Centre for Quantifiable Quality of Service in Communication Networks Dept. of Telematics, NTNU 19.06.09. Tor K Moseng, Handoff in Wireless Internet Access. Outline. Introduction Horizontal Handover

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Tor K Moseng, Handoff in Wireless Internet Access

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  1. Trial Lecture Vertical and Horizontal Handoff in Wireless Internet Access Tor K Moseng Centre for Quantifiable Quality of Service in Communication Networks Dept. of Telematics, NTNU 19.06.09 Tor K Moseng, Handoff in Wireless Internet Access

  2. Outline • Introduction • Horizontal Handover • Handover in GSM • Handover in WiFi • Vertical Handover • Handover UMTS-WiFi • Handover Approaches • Standards • IEEE 802.21 • UMA • CALM • Visions Tor K Moseng, Handoff in Wireless Internet Access

  3. Introduction Internet Wireless Internet Access • Different wireless networks available • E.g. GSM/GPRS, UMTS, WiFi, WiMAX • Mobility is Essential • Changes the users’ behavior • Internet access from any wireless device • Always best connected • Multi-mode equipment Tor K Moseng, Handoff in Wireless Internet Access

  4. Introduction Wireless Internet Access • What is handover? • Changing the point of connection while communicating • Why is handover needed? • Mobility • User preferences • What is the objective? • Handover procedure without a users notice  Seamless handover Tor K Moseng, Handoff in Wireless Internet Access

  5. Introduction Network Coverage WPAN WLAN WMAN WWAN Satellite Bluetooth RFID WiFi IEEE 802.11 WiMAX IEEE 802.16 GSM/GPRS UMTS GPS GALILEO Wireless Metropolitan Area Network – City wide Wireless Personal Area Network – In a person’s proximity Wireless Local Area Network – Home, Hotel, Airport Satellite – Worldwide coverage Wireless Wide Area Network – Regional, Cellular systems Tor K Moseng, Handoff in Wireless Internet Access

  6. Introduction – Use Case 1 BSC BS1 BS2 BS3 1. Connect to BS1 and start conversation 2. Moving out of BS1’s coverage – connect to BS2 3. Moving out of BS2’s coverage – connect to BS3 4. Conversation ended – still within BS3’s coverage Tor K Moseng, Handoff in Wireless Internet Access

  7. Introduction – Use Case 2 Ethernet Ethernet WiFi WiFi Ethernet UMTS UMTS WiFi UMTS Ethernet WiFi UMTS UMTS WiFi WiFi Ethernet 2. Moving indoor 4. Moving into a hot-spot 3. Moving outdoor 1. Wired connection at the working desk Tor K Moseng, Handoff in Wireless Internet Access

  8. Horizontal Handover Horizontal Handover • Horizontal handover is when a mobile terminal changes its point of connection within the same type of network • E.g. from a cell to another in GSM • E.g. from an access point to another in WiFi • Reasons for handover • Worse signal quality or loss of signal • Traffic load balancing • Cost Tor K Moseng, Handoff in Wireless Internet Access

  9. MSC Horizontal Handover BSC BSC BSC MSC BSC Handover in GSM • Network-controlled, mobile terminal assisted handover • The network takes the handover decisions • The mobile terminal supervises and reports its signal quality • Three types of handover • Intra-BSC handover • Inter-BSC handover • Inter-MSC handover Tor K Moseng, Handoff in Wireless Internet Access

  10. Horizontal Handover IAPP (IEEE 802.11f) Handover in WiFi • Mobile terminal-controlled, network assisted handover • The mobile node chooses new AP to re-associate with • The network exchanges information after re-association • Handover in four parts Distribution System 1a. Probe request 1b. Probe response 2. Authentication 3. Re-association 4. Connection handover 1a. Probe request 1b. Probe response 2. Authentication 3. Re-association 4. Connection handover 1a. Probe request 1b. Probe response 2. Authentication 3. Re-association 4. Connection handover 1a. Probe request 1b. Probe response 2. Authentication 3. Re-association 4. Connection handover 1a. Probe request 1b. Probe response 2. Authentication 3. Re-association 4. Connection handover 1a. Probe request 1b. Probe response 2. Authentication 3. Re-association 4. Connection handover AP1 AP2 BSS1 BSS2 Tor K Moseng, Handoff in Wireless Internet Access

  11. Vertical Handover Vertical Handover • Vertical handover is when a mobile terminal changes its point of connection in a different type of network • E.g. from a wired Ethernet connection to an access point in WiFi • E.g. from an access point in WiFi to a cell in UMTS • Reasons for handover • Worse signal quality or loss of signal • Performance requirements (e.g. bandwidth) • Cost • Power consumption Tor K Moseng, Handoff in Wireless Internet Access

  12. Vertical Handover Challenges in Vertical Handover • Multi-mode devices • Power consumption • QoS • Available capacity • Security • Timing • The business model • Session continuity Tor K Moseng, Handoff in Wireless Internet Access

  13. Vertical Handover Handover UMTS-WiFi • Open coupling • No common subscriber database and billing • Poor handover performance • Loose coupling • Common subscriber database and billing • Improved handover performance • Tight coupling • UMTS core network interface must be supported  single operator • Improved handover performance Tor K Moseng, Handoff in Wireless Internet Access

  14. Vertical Handover Handover UMTS-WiFi • Open coupling • Loose coupling • Tight coupling • Open coupling • Loose coupling • Tight coupling • Open coupling • Loose coupling • Tight coupling Internet AAA UMTS Core Network WiFi Gateway RNC Node B Node B AP AP AP Node B Tor K Moseng, Handoff in Wireless Internet Access

  15. Handover Approaches Handover Approaches • Handover objective is a seamless handover • Smooth handover: low loss • Fast handover: low delay • Smooth and fast handover gives a seamless handover • Lower layers handover • Hard handover • Soft handover • Network layer mobility • Mobile IP Tor K Moseng, Handoff in Wireless Internet Access

  16. Handover Approaches Hard Handover ”break before make” • Old connection is broken before a new connection is activated • Primarily used in FDMA and TDMA systems (e.g. GSM) • Different frequency ranges used in adjacent cells to minimize the interference • When to perform hard handover? • E.g. based on measurements of the signal quality • Different schemes to avoid unnecessary handovers Tor K Moseng, Handoff in Wireless Internet Access

  17. Handover Approaches Soft Handover ”make before break” • New connection is activated before the old is broken • Used in UMTS to improve the signal quality • Uplink and downlink signals may be combined for better signal • A mobile may in UMTS spend a large part of the connection time in soft handover • Better connection reliability • More seamless handover Tor K Moseng, Handoff in Wireless Internet Access

  18. Handover Approaches Mobile IP • Changing the point of connection may change the IP-address • Disrupting the on-going session • Mobile IP is a network-layer mobility management solution • Hides the mobile node’s movement from its corresponding node • Two IP-addresses involved • Home Address: the point of contact for corresponding nodes • Care-of-Address: the current point of connection • Two agents involved • Home Agent: acts as a proxy and forwards packets to the CoA • Foreign Agent: allows mobile nodes to register in ”foreign” subnets Tor K Moseng, Handoff in Wireless Internet Access

  19. Handover Approaches Mobile IP Home Network Home Agent Home Address  Care-of-Address Corresponding Node Home Address 1. Session with Home Network Foreign Network 2. Move to a Foreign Network Foreign Agent 3. Register its presence and Care-of-address 4. Session with Foreign Network Care-of-Address Tor K Moseng, Handoff in Wireless Internet Access

  20. Standards Standards for vertical handover • IEEE 802.21 • Unlicensed Mobile Access (UMA) • Continous Air-Interface for Long and Medium range (CALM) Tor K Moseng, Handoff in Wireless Internet Access

  21. Standards – IEEE 802.21 IEEE 802.21 • Support seamless vertical handover • Media Independent Handover (IEEE Std 802.21-2008, January 2009) • Assess on-going work related to handover in IEEE, IETF and 3GPP • GSM/GPRS, UMTS, IEEE 802.3/11/15.3/16/20 • Goals • Framework for vertical handover • Different vendors, operators and users • Not covered • Handover policy • Security  What about the business model? Tor K Moseng, Handoff in Wireless Internet Access

  22. Standards – UMA Unlicensed Mobile Access (UMA) • 3GPP standard for cellular systems and unlicensed wireless networks handover • A mobile centric version of IEEE 802.21 • The UMA Network Controller (UNC) • Provides an interface into mobile operators core network • Secure transport of mobile signaling over IP • Extends a mobile operator’s services over IP-based access networks • Use WiFi to improve coverage and performance of 3G services Tor K Moseng, Handoff in Wireless Internet Access

  23. Standards – CALM CALM • ISO approved framework for continuous communication across various interfaces and media for vehicular users • ISO TC204/WG16 – Wide Area Communications • IEEE 802.11/11p/15/16e/20, 2G/3G, and ITS systems • Application support • In-vehicle Internet access • ITS applications (focus on Vehicle Safety Communication) • V2V communication • Vertical handover based on IPv6 protocols (ISO 21210) Tor K Moseng, Handoff in Wireless Internet Access

  24. Visions Visions • 4G network: Universal wireless access with much higher data rates than today • Collection of technologies and protocols • Not just one single standard • Seamless handover and roaming • QoS support • Prediction of availability is 2015 (ref:Phil Redman, Gartner) ”Anytime, Anywhere” Tor K Moseng, Handoff in Wireless Internet Access

  25. Visions Visions • The Wireless World Research Forum (WWRF) formulates visions on strategic future research directions in the wireless field Networks for the Wireless World must enable application- and service-independent end-to-end reachability in the global network environment. Networks for the Wireless World should be capable to support both existing and new mobility mechanisms that enable terminals and networks to move around without being closely tied to so-called ”home” networks. Tor K Moseng, Handoff in Wireless Internet Access

  26. References References • 3GPP, [Online]: www.3gpp.org • Jacques De Kegel, IBM & Wireless 2004, Presentation WIreless e-business EBO, [Online]: http://www.ti.kviv.be/Ittelecom/EBO_overview.pdf • Knut Evensen, CALM Architecture and CALM M5 Convenor, Presentation at IEEE 802 Plenary Tutorials, November 2006 • Hussain et al., Mobility Management Challenges and Issues in 4G Heterogeneous Networks, In Proceedings of InterSense'06, May 2006 • IEEE, [Online]: www.ieee.org • IETF, [Online]: www.ietf.org • Juha Korhonen, Introduction to 3G Mobile Communications, 2nd Ed, Artech House, 2003 • Lim et al., SHARE: Seamless Handover Architecture for 3G-WLAN Roaming Environment, Wireless Networks, 15:353-363, 2009 • Network World, [Online]: www.networkworld.com • Charles Perkins, Presentation at an IEEE 802 Handoff Tutorial, November 2002, [Online]: http://ieee802.org/16/tutorial/T80216-02_04.zip • Bjørn Rønning, UMTS og WLAN - konkurrerende eller komplimentære systemer, Norsk UMTS-forum, Oktober 2001, [Online]: http://www.umts.no/files/30Okt01-Bj%C3%B8rnR%C3%B8nning-%20UMTS%20forum.pdf • Sharma et al., OmniCon: A Mobile IP-based Vertical Handoff System for Wireless LAN and GPRS Links, In Proceedings of ICPP 2004 Workshops, 2004 • UMA Today, [Online]: www.umatoday.com • Wikipedia, The Free Encyclopedia, [Online]: http://en.wikipedia.org • Wireless World Research Forum, [Online]: http://www.wireless-world-research.org/ • Qing-An Zeng and D.P.Agrawal, Handoff in Wireless Mobile Networks, Chapter 1, Handbook of Wireless Networks and Mobile Computing, 2002 Tor K Moseng, Handoff in Wireless Internet Access

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