ECE/CSC 575 – Section 1 Introduction to Wireless Networking

1. ECE/CSC 575 – Section 1 Introduction to Wireless Networking Lecture 14Dr. Xinbing Wang

2. Part 3: Current Wireless Systems • Cellular network architecture: UMTS (Chapter 10) • Mobile IP (Chapter 12) • Objectives and requirements of Mobile IP • Mobile IP operation: advertisement, registration, and tunneling. • Triangle routing and optimization routing • Mobile IPv6 • Open question: where will mobile IP be used? • Labs: registration, handoff, and authentication • Wireless LAN (Chapters 11/13/14) Dr. Xinbing Wang

3. Mobile IPv6 • Based on IPv6, using IP routing header, authentication header, and route optimization. • There is NO foreign agent. The MN obtains a colocated care-of-address on a foreign link, and reports to its HA. • One MN may have multiple care-of-addresses. • The security functions are mandatory instead of optional. • Binding: The association of the home address of an MN with a care-of-address that MN, along with the remaining lifetime of that association. Dr. Xinbing Wang

4. Mobile IPv6 messages • Mobile IPv6 requires the exchange of additional information. All new messages used in mobile IPv6 are defined as IPv6 destination options. • Binding Update: an MN informs its HA or any other CNs about its current CoA. Any packet including a Binding Update must also include an AH or ESP header. • Binding Acknowledgement: to acknowledge the receipt of a Binding Update, if an ACK was requested, it must also include an AH or ESP header. • Binding Request: for any node to request an MN to send a Binding Update with the current CoA. • Home Address : used in a packet sent by an MN to inform the receiver of this packet about the MN’s home address. This message must also be covered by the authentication. Dr. Xinbing Wang

5. Data Structures • Binding Cache: Every IPv6 node has a Binding Cache which is used to hold the bindings for other nodes. If a node receives a Binding Update, it will add this binding to its Binding Cache. • Binding Update List: Every MN has a Binding Update List which is used to store information about each Binding Update sent by this MN for which the lifetime has not expired. It contains all Binding Updates sent to any CNs and to its HA. • Home Agent List: Each HA generates a list, which contains information about other HAs on a home link. Dr. Xinbing Wang

6. FA Mobile IPv6 Operation Home network/ Subnet CN do not know the MN’s CoA HA Internet Backbone CN knows the MN’s CoA Foreign Network/ Subnet Dr. Xinbing Wang

7. Home Agent Registration • Route Optimization: To avoid triangle routing, an MN can send Binding Update to any CN. This allows IPv6 nodes to cache the current CoA address and send packets directly to an MN. The MN sends a Binding Update to the HA Internet Backbone HA FA Home network/ Subnet Foreign Network/ Subnet The HA accepts the Binding Update and returns a Binding Acknowledgement Dr. Xinbing Wang

8. Part 3: Current Wireless Systems • Cellular network architecture: UMTS (Chapter 10) • Mobile IP (Chapter 12) • Objectives and requirements of Mobile IP • Mobile IP operation: advertisement, registration, and tunneling. • Triangle routing and optimization routing • Mobile IPv6 • Open question: where will mobile IP be used? • Labs: registration, handoff, and authentication • Wireless LAN (Chapters 11/13/14) Dr. Xinbing Wang

9. Wireless LAN-IEEE 802.11(Chapter 13/14) • It is the standard for wireless LANs. • It specifies MAC procedures and operate in 2.4 GHz range with data rate of 1Mbps or optionally 2Mbps. • User demand for higher bit rates and international availability of 2.4 GHz band has resulted in development of a high speed standard in the same carrier frequency range. • This standard called 802.11b, specifies a PHY layer providing a basic data rate of 11 Mbps and a fall-back rate of 5.5 Mbps. Dr. Xinbing Wang

10. IEEE 802.11b • The IEEE 802.11 and 802.11b standards can be used to provide communication between a number of PSs (Peer Stations) as an ad hoc network using peer to peer mode • As a client server wireless configuration • Complicated distributed network Dr. Xinbing Wang

11. Wireless LAN Infrastructure Network AP: Access Point AP AP wired network AP Ad-hoc Network Dr. Xinbing Wang

12. Protocol Architecture fixed terminal mobile terminal infrastructure network application application access point TCP TCP IP IP LLC LLC LLC MAC MAC 802.3 MAC 802.3 MAC PHY PHY 802.3 PHY 802.3 PHY Dr. Xinbing Wang

13. Protocol Layers and Functions • MAC • access mechanisms, fragmentation, encryption • MAC Management • synchronization, roaming, MIB (management information base), power management • PLCP Physical Layer Convergence Protocol • clear channel assessment signal (carrier sense) • PMD Physical Medium Dependent • modulation, coding • PHY Management • channel selection, MIB • Station Management • coordination of all management functions Station Management LLC DLC MAC MAC Management PLCP PHY Management PHY PMD Dr. Xinbing Wang

14. Basics of Wireless LANs • Coverage area, data rate, and battery consumption. • Characterized by small coverage areas (~200m), but relatively high bandwidths (data rates) (upto 50Mbps currently) • Major standards • WLAN: IEEE 802.11 and HIPERLAN. • WPAN: IEEE 802.15 (Bluetooth) and HomeRF Dr. Xinbing Wang

15. WLANs – Advantages • Buildings with large open areas, such as manufacturing plants, stock exchange trading floors, and warehouses • Historical buildings with insufficient twisted pair and where drilling holes for new wiring is prohibited • Small offices where installation and maintenance of wired LANs is not economical • Very flexible within the reception area • Users can access high speed multimedia applications anywhere at anytime, with easy implementation, low cost, and wide user acceptance • Generally works in industrial, scientific, and medical (ISM) band, which is un-licensed and available for public. • (Almost) no wiring difficulties (e.g. historic buildings, firewalls) Dr. Xinbing Wang

16. Disadvantages of WLANs • Typically very low bandwidth compared to wired networks (1-10 Mbit/s) • Many proprietary solutions, especially for higher bit-rates, standards take their time. • Products have to follow many national restrictions if working wireless, it takes a very long time to establish global solutions. • Interference Problems Dr. Xinbing Wang

17. Family of Wireless LAN (WLAN) Standards 802.11 • 802.11a - 5GHz- Ratified in 1999 • 802.11b - 11Mb 2.4GHz- ratified in 1999 • 802.11d - Additional regulatory domains • 802.11e - Quality of Service • 802.11f - Inter-Access Point Protocol (IAPP) • 802.11g - Higher Data rate (>20MBps) 2.4GHz • 802.11h - Dynamic Frequency Selection and Transmit Power Control mechanisms • 802.11i - Authentication and security Dr. Xinbing Wang

18. WLANs –Current Use • Home wireless networks. • Enterprise wireless networks. • Public access. • Hospitals. • Warehouses. • Consulting and audit teams • Dynamic environments, ad agencies, etc. • Universities • Historic buildings, older buildings. • Meeting rooms. • Retail stores • Restaurants and car rental agencies • Data backup. Dr. Xinbing Wang

19. Some Facts • By 2005, more than 1/3rd of Internet users will have Internet connectivity through a wireless enabled device (750 million users)!!! (Source: Intermarket group) • By the end of 2001, more than half of the workforce in the US uses a wireless net device – primarily cellular phones! (Source: Cahners Intat Group) • By the year 2004 revenue from wireless data will reach $34B, and by the year 2010 the number of wireless data subscribers will hit 1B!! Dr. Xinbing Wang

20. Design Goals for Wireless LANs • Global, seamless operation (must sell in all countries) • Low power for battery use (power saving modes and power management functions) • No special permissions or licenses needed to use the LAN • Robust transmission technology (avoid interference) • Simplified spontaneous cooperation at meetings • Easy to use for everyone, simple management • Protection of investment in wired networks (interoperable with wired LANs) • Security (no one should be able to read my data), privacy (no one should be able to collect user profiles), safety (low radiation) Dr. Xinbing Wang

21. Real Time Traffic Normal Data Traffic (Asynchronous) Point Coordination Function (PCF) MAC DistributedCoordination Function (DCF) Physical Layer (PHY) WLANs – 802.11 Protocol Architecture Dr. Xinbing Wang

22. IEEE 802.11- Physical Medium Specification Three Physical Media: • INFRARED • Narrowband Microwave • Spread Spectrum Dr. Xinbing Wang

23. Infrared • Infrared signals used to transmit data (similar to TV remotes!) • Higher data rates possible (than spread spectrum) • Line of sight point-to-point configuration required (or reflection surface that reflects signals) • Too sensitive to obstacles, line-of-sight requirement, etc. • 850-950 nm, diffuse light (to allow point-to-multipoint communication) • 10 m maximum range with no sunlight or heat interfere Dr. Xinbing Wang

24. Narrowband Microwave • Typically used to link two WLANs together (for example, to link WLANs in two buildings) • Microwave dishes required at both ends of link • Unlike spread spectrum which operates in the unlicensed ISM band, narrowband microwave requires FCC licensing • Exclusive license typically effective within a 17.5 mile radius Dr. Xinbing Wang

25. Spread Spectrum • Distributed signals over multiple frequencies (to avoid eavesdropping or jamming) • Frequency Hopping Spread Spectrum (FHSS) • Sender transmits over a seemingly random series of frequencies • Intended receiver aware of sequence of frequencies and hops accordingly • Allows the coexistence of multiple networks in the same area by using different hopping sequences • Direct Sequence Spread Spectrum (DSSS) • Sender transmits redundant information called “chips” between actual data bits • Intended receiver aware of spread removes redundant information accordingly • Preamble and header of a frame is always transmitted with 1 Mbit/s, rest of transmission 1 or 2 Mbit/s Dr. Xinbing Wang

26. Wireless LAN Classification • Infrared (IR) LANs • An individual cell of an IR LAN is limited to a single room, since infrared light does not penetrate opaque walls. • Spread Spectrum LANs • In most cases these LANs operate in the ISM (industrial, scientific, and medical) bands, so no FCC licensing is required for their use in the United States. • Narrowband Microwave LANs • These LANs operate at microwave frequencies but do no use spread spectrum. Some of these products operate at frequencies that require FCC licensing; others use one of the unlicensed ISM bands. Dr. Xinbing Wang

27. Infrared uses IR diodes, diffuse light, multiple reflections (walls, furniture etc.) Advantages simple, cheap, available in many mobile devices no licenses needed Disadvantages interference by sunlight, heat sources etc. many things shield or absorb IR light low bandwidth Line of Sight Problem Example IrDA (Infrared Data Association) interface available everywhere: PDAs, calculators, laptops, mobile phones... Radio typically using the license free ISM band at 2.4 GHz Advantages experience from wireless WAN and mobile phones can be used coverage of larger areas possible (radio can penetrate walls, furniture etc.) Disadvantages very limited license free frequency bands shielding more difficult, interference with other electrical devices Example WaveLAN, HIPERLAN, Bluetooth Comparison: Infrared vs. Radio Transmission Dr. Xinbing Wang

28. Overview of WLAN Classification Dr. Xinbing Wang

29. After Class • Reading materials • Chapter 13.1-13.4 • Chapter 14.1-14.2 • Exercises • What is the main difference between Mobile IPv6 and MIPv4? • List and briefly define four application areas for wireless LANs • What is the difference between a single-cell and a multiple-cell wireless LAN? • Describe infrared, narrowband, and spread spectrum wireless LANs Dr. Xinbing Wang