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

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) In our daily lives, wireless communication technology is used everywhere, from VCR remote control, to satellite weather forecast. The common characteristics of wireless communication systems is that there is no physical (visible) lines between two communication parties. Therefore, a wireless system is able to support user roaming. For example, we do not have to use a remote control in a particular position to.., we can use our cellular phones almost everywhere. However, there are many impairments to a wireless channel, causing a lot of limitations to wireless communications system such as geographical.. (signal fading, additional noise, cochannel interference. Wireless systems also suffers from limit usable spectral width, so that the transmission rate is relatively low. Specifically, wireless cellular systems based on radio propagation has been evolving from narrow band (1G, late 170s) to wide-band(3G). With their geographical coverage limitation, wireless systems need a backbone network to extend their geographical coverage to enable global communications. The interoworking of a wireless network as the front-end and the Internet as the backbone has received much attention in recent years. So we will first take a look at the network architecture of current wireless systems,…, Then we will talk about the evolution from 2G to 3G systems. Dr. Xinbing Wang

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

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

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

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

Home Agent Registration 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 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. Dr. Xinbing Wang

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) In our daily lives, wireless communication technology is used everywhere, from VCR remote control, to satellite weather forecast. The common characteristics of wireless communication systems is that there is no physical (visible) lines between two communication parties. Therefore, a wireless system is able to support user roaming. For example, we do not have to use a remote control in a particular position to.., we can use our cellular phones almost everywhere. However, there are many impairments to a wireless channel, causing a lot of limitations to wireless communications system such as geographical.. (signal fading, additional noise, cochannel interference. Wireless systems also suffers from limit usable spectral width, so that the transmission rate is relatively low. Specifically, wireless cellular systems based on radio propagation has been evolving from narrow band (1G, late 170s) to wide-band(3G). With their geographical coverage limitation, wireless systems need a backbone network to extend their geographical coverage to enable global communications. The interoworking of a wireless network as the front-end and the Internet as the backbone has received much attention in recent years. So we will first take a look at the network architecture of current wireless systems,…, Then we will talk about the evolution from 2G to 3G systems. Dr. Xinbing Wang

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Infrared Higher data rates possible (than spread spectrum) 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

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

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

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

Comparison: Infrared vs. Radio Transmission 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 Dr. Xinbing Wang

Overview of WLAN Classification Dr. Xinbing Wang

After Class Reading materials Exercises Chapter 13.1-13.4 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