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IS516 Computer Communication and Networks การสื่อสารคอมพิวเตอร์และเครือข่าย. Asst.Dr.Surasak Mungsing [email protected] [email protected] Sripatum University. Lecture 09 Wireless Networking. Topic.

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Computer Communication and Networks

Asst.Dr.Surasak Mungsing [email protected] [email protected]://

Sripatum University

Lecture 09Wireless Networking


  • Introduction to Wireless Technologies

  • Wireless Networking Overview

  • Non-Technical considerations

  • Other Comparable Technologies

Access Point

Wireless NIC cards

What is Wi-Fi

Wi-Fi is an abbreviation for Wireless Fidelity and a catch all phrase for the several different standards and recommendations that comprise wireless networking.

Wi-Fi enables the user to deploy a computer network without needing to run cable throughout the facility.

International standard for wireless networking that operates in the 2.4 GHz frequency range (2.4 GHz to 2.4835 GHz) and provides a throughput of up to 11 Mbps with a range of just over 300 feet indoors. This is a very commonly used frequency. Microwave ovens, cordless phones, medical and scientific equipment, as well as Bluetooth devices, all work within the 2.4 GHz frequency band.

Standard: IEEE 802.11b 2.4GHz - 11 Mbps

Standard: IEEE 802.11b 2.4GHz - 11 Mbps

802.11b enables transfers of up to 11 Mbps. Comparable to 10BaseT in speeds, 802.11b is the most common wireless standard deployed today. In comparison T1 speeds are 1.54Mbps and DSL is normally in the 640Kbps range.Most deployments of Wireless utilize 802.11b

International standard for wireless networking that operates in the 5 GHz frequency range (5.725 GHz to 5.850 GHz) with a maximum 54 Mbps data transfer rate. The 5 GHz frequency band is not as crowded as the 2.4 GHz frequency, because the 802.11a specification offers more radio channels than the 802.11b. These additional channels can help avoid radio and microwave interference.

Cost of 802.11a equipment is approximately twice that of 802.11b and current deployment is limited.

Standard: IEEE 802.11.a 5 GHz - 54 Mbps


IEEE 802.11.a 5GHz 11Mbps


  • IEEE 802.11b 2.4GHz 11Mbps

  • IEEE 802.11a 5GHz 54 Mbps

  • IEEE 802.11g 2.4Ghz Hybrid 11/54Mbps

    802.11g is in the final stages of development. The current draft (V5.0) is open for comments until January 8, 2003.

Limitations of WiFi

  • 300 ft. effective range from access point

    • 1400 ft maximum range

  • Structural interference

  • Interference from other devices such as cordless phones.


  • Any application currently used on a traditional wired network can be used on a wireless network.

  • New applications may be available or can be developed to take advantage of wireless, such as Wireless PDA access to a card catalog.

Wireless Network Components

  • APAccess Points

  • NICs - Network Interface Cards

    • PCMCIA

    • USB

    • PCI

    • CompactFlash

  • Other Wireless Devices

    • Bridges and Routers

    • Print Servers

  • PCs, Laptops, PDAs

Connecting To a Legacy Network

Access Points connect the wireless network to the legacy network.

Why Deploy Wireless?

  • Cost savings over wireline.

  • Can not run wire to locations needed.

  • To enable patrons to bring their own laptop, therefore reducing the cost of owning many PCs.

  • To enable you to easily move PCs.

  • To be on the leading edge.

Environment Assessment

  • Look at the structure of your building.

    • Steel, Concrete, Stone, Glass

    • Open w/ few walls or many separate rooms?

  • Current technologies used

    • Do you use a 2.4 GHz cordless phone? Does it work throughout your environment?


  • 802.11b Wireless Access Points start around $130.00 for basic connectivity and run up to $500.00 for more management features.

  • 802.11b Network Interface Cards (NICs) cost between $50-$100 and come in USB, PCI, PCMCIA and CompactFlash versions.

The A-B-Gs of Wireless

Which standard is right for you?

  • 802.11a

    • 54 Mbps @ 5MHz

    • Not widely adopted

  • 802.11b

    • 11 Mbps @2.4GHz

    • Low Cost

  • 802.11g

    • New technology - Available late 2003

    • Compatible with 802.11b

Bluetooth 802.15

Bluetooth is the standard for wireless personal area networks or WPAN.

It allows high speed transmission of data over very short distances.

Bluetooth is normally used for transferring data between laptops, or in Internet Kiosk type applications where roaming is not needed.

IEEE 802.16(WiMAX)

IEEE 802.16(WiMAX)

IEEE 802.16(WiMAX)

  • WiMAX (Worldwide Interoperability for Microwave Access)IEEE 802.16IEEE 802.16a 2004 IEEE (Institute of Electrical and Electronics Engineers) 30 ( 48 ) 75 (Mbps) 10 30 3G

IEEE 802.16(WiMAX) ()

IEEE 802.16a (Point-to-Multipoint) Non-Line-of-Sight IEEE 802.16a 2-11 (GHz) IEEE 802.16a IEEE 802.16a (QoS) (Video) (Voice) (Low Latency Network) Security (Privacy) (Authentication) (Encryption)

IEEE 802.16(WiMAX) ()

  • WiMAX- IEEE 802.16 1.6-4.8 LoS (Line of Sight) 10-16 GHz- IEEE 802.16a IEEE 802.16 2-11 GHz 802.16 NLoS (Non-Line-of-Sight) 30 75 Mbps WiMAX 1 (T1-Type) 60 DSL - IEEE 802.16e 1.6-4.8

Mobile Phones

Smart Phones

Mobile Phone

  • (Generation) 1G, 2G, 3G, 4G

  • (First Generation) (Voice) AMPS (Advanced Mobile Phone Service), TACS

  • (Multiple Access) FDMA(Frequency Division Multiple Access)

2G (Second Generation : 2G)

  • (Second Generation) FDMA TDMA (Time Division Multiple Access)

  • TDMA (Time Division Multiple Access)

  • Digital Amps GSM (Global System for Mobile Communications)

2G (Cont.)

  • ,

  • 9600 bps


  • GPRS(General Packet Radio Service)

  • Packet


  • AIS

  • MobileLIFE"


  • DTAC 2.75 EDGE

  • EDGE : Enhanced Data rates for Global Evolution

  • 2.75G

  • EDGE ..2538


  • EDGE 3 G

  • EDGE 473.6Kbps 384Kbps EDGE GSM384

3G (Third-generation Wireless :3G)

  • NTT DoCoMo 3G 2001

  • 3G 3G


  • 3 (Third-generation Wireless ; 3G)

  • , , , Hutch

  • Hutch 3 2000 (CDMA 2000 1X) MMS (Multimedia Messaging Service)

4G (Fourth Generation)

  • 4 2553

  • 4 100 1 3

Security Overview

  • WEP - Wired Equivalent Privacy

    40 bit vs. 128 bit

    Is Encryption Necessary?

  • Open access vs. Secured

  • Other Security Measures

    Content Filtering

    Network Partitioning

Security(Encryption, Content Filtering, Privacy, etc.)

Partition The Network

  • A safe practice is to create two separate networks. A private network for day to day business and a network for public access. Both can be wireless. These networks can talk to one another through a proxy server that will protect the private network from malicious attacks via the public network.

Security(Encryption, Content Filtering, Privacy, etc.)


  • Encryption on the pubic network can be used but would create administrative overhead. Encryption keys would have to be changed regularly and anyone using their own laptop would have to be given the key.

  • Encryption works best in a network that does not allow people to use their own laptops.

  • Encryption increases privacy, but can be thwarted, either by software, or by gaining access to a PC configured with wireless and writing down the key.

Security(Encryption, Content Filtering, Privacy, etc.)

Content Filtering & Proxy Servers

Web content filtering that has generally been software on the desktop would have to be handled by a server if people are allowed to use their own laptops.

Proxy servers allow you to control what information people have access to. This is a good practice anyway, allowing you to control at a global level what information travels over your network. It also allows you to track usage.

Security(Encryption, Content Filtering, Privacy, etc.)

Viruses and Hacker

  • Wireless does not add any additional threat in the way of viruses.

  • Anyone, anywhere can attack a network that is connected to the Internet. Wireless does not increase that chance. Security measures such as firewalls, can reduce the risk.

Security Planning

Develop a Security Plan. It should include:

  • What are your special security needs?

  • What known vulnerabilities exist?

  • How to safe guard against the risks?

  • How do you recover from a security breech?

Virtual Hours

Your wireless network may not stop at your door. This means anyone can access your network after hours by sitting outside with a laptop.


  • NIC Wi-Fi

LAN ()

  • IEEE802.11b SSID (Service Set Identifier) MAC (Media Access Control)

LAN ()

  • WEP(Wired Equivalent Privacy) AP MAC LAN

  • Authentication UsersRADIUS

Next Lecture

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