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

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. 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

7. 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

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)
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

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 b, 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 b
The IEEE and b 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 Ad-hoc Network AP: Access Point 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 and HIPERLAN.
WPAN: IEEE (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. 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

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

23. 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.
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. 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

28. Overview of WLAN Classification
Dr. Xinbing Wang

29. 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