Chapter 01

Wireless Standards,Organizations, and Applications

Center for Information Technology

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Why Standards are need?

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Objectives

Define the roles of the organizations

- Regulatory Domain Governing Bodies

- IEEE

- Wi-Fi Alliance

Identify some of the uses for spread spectrum technologies

- Wireless LANs, PANs, MANs, and WANs

Identify technology roles for WLAN technologies

Advantages and Disadvantages of WLAN

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Roles Organizations PlayWithin the WLAN Industry

There are three primary categories of organizations that guide the wireless industry. These categories include regulation, standardization, and compatibility.

The Federal Communications Commission (FCC) is an example of regulatory bodies.

The Institute of Electrical and Electronics Engineers (IEEE) is an example of a standards development organization

The Wi-Fi Alliance is a compatibility testing and certification group.

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FCC – IEEE – Wi-Fi Alliance

The FCC sets the boundaries within which the IEEE may develop standards.

The Wi-Fi Alliance tests equipment to certify it as being reasonably interoperable.

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FCC

WLAN devices use radio wave communications, they fall under the regulatory control of the FCC.

The factors regulated by the FCC include:

■ Radio frequencies available

■ Output power levels

■ Indoor and outdoor usage

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FCC

Radio Frequencies Available

The FCC regulates which frequencies may be used within the regulatory domain it manages

The FCC provides two types of license-free bands for radio communications: the Industrial Scientific Medical (ISM) bands and the Unlicensed National Information Infrastructure (U-NII) bands.

2.4 GHz is used by IEEE 802.11. U-NII bands exist in the 5 GHz frequency range, and are all used by IEEE 802.11

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FCC

Output Power Levels

The 2.4 GHz ISM band may be used indoors or outdoors, and the output power at the intentional radiator cannot exceed 1 watt.

For indoor devices, the output power is usually well under 1 watt and generally resides in a range from 30 to 300 milliwatts.

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IEEE

The Institute of Electrical and Electronics Engineers

The IEEE developed standards that impact and benefit wireless networking.

These standards include wireless specific standards as well as standards that have been implemented in the wired networking domain, which are now being utilized in the wireless networking domain.

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IEEE 802.11 standards

IEEE 802.11b-1999 (amended slightly in 2001)

Uses high-rate direct-sequence spread spectrum (HR/DSSS) instead of the original DSSS.

Provides data rates up to 11 Mbps.

Uses the 2.4 GHz ISM band.

Backward compatible with DSSS.

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IEEE 802.11g-2003

Supports DSSS and HR/DSSS and adapts OFDM modulation to 2.4 GHz band.

Provides data rates up to 54 Mbps.

IEEE 802.11 standards

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IEEE 802.11n (2008)

Defines modifications to the IEEE 802.11 physical and media access control layers that will allow for much higher throughputs and a maximum throughput of at least 100 Mbps.

This is currently being accomplished with the use of MIMO (multiple-input-multiple-output) technology in conjunction with OFDM technology.

IEEE 802.11 standards

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Wi-Fi Alliance

The Wi-Fi Alliance is a certification organization that provides testing and interoperability analysis for the wireless industry.

While the FCC makes the rules and the IEEE determines how to live within those rules, the Wi-Fi Alliance ensures that devices are compatible with the IEEE’s way of implementing WLAN technology.

Only products of Alliance members that have been tested successfully by the Wi-Fi Alliance are actually allowed to claim that they are Wi-Fi Certified.

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Spread Spectrum Technology Uses

Spread spectrum technology is used in multiple ways that can be organized within four primary categories: wireless LANs, wireless PANs (WPANs), wireless MANs (WMANs) and wireless WANs.

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Wireless LANs

There are three primary roles that wireless LANs play in today’s enterprise organizations:

■ Access role

■ Distribution role

■ Core role

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In the access role, the wireless network is used to provide wireless clients with access to wired resources. The access point remains fixed while the clients may move.

The access point is usually connected to an Ethernet network where other resources, such as file servers, printers,…, reside.

In this role, the access point provides access to the wireless medium first and then, when necessary, provides bridging to the wired medium or other wireless networks

Access role

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In the distribution role, wireless bridges provide a backhaul connection between disconnected wired networks.

In this case, each network is connected to the Ethernet port of a wireless bridge and the wireless bridges communicate with each other using the IEEE 802.11 standard.

Once these connections are made, network traffic can be passed across the bridge link so that the two previously disconnected networks may act as one.

Distribution role

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Distribution role

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In the core role, the wireless LAN is the network. This

may be suitable for small networks built on-the-fly, such

as those built at construction sites or in disaster areas.

However, the limited data throughput will prohibit the

wireless LAN from being the core of the network in a

large enterprise installation.

Core role

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Core role

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Wireless PANs

A wireless PAN (personal area network) provides hands-free connectivity and communications within a confined range and limited throughput capacity.

Bluetooth is a perfect example of a wireless PAN technology that is both beneficial and in widespread use.

Operating in the 2.4 GHz ISM band, Bluetooth technologies can cause interference with wireless LAN technologies like DSSS, HR/DSSS, and ERP. However, the newer adaptive frequency hopping technology helps to reduce this interference if not completely remove it. Adaptive frequency hopping is a new feature found in Bluetooth 1.2 devices and higher.

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Wireless PAN Network

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Wireless MANs

WiMAX is the most commonly referenced wireless MAN technology.

WiMAX is based on the IEEE 802.16 standard and provides expected throughput of approximately 40 Mbps for fixed, line of sight connections and approximately 15 Mbps for mobile, non–line of sight connections.

In addition to the throughput speeds, WiMAX incorporates QoS mechanisms that help to provide greater throughput for all users and important applications using the network.

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Wireless WANs

Wide area networks (WANs) are usually used to connect LANs together. If the LANs are separated by a large distance, WAN technologies may be employed to connect them. These technologies include Frame Relay, analog dial-up lines, Digital Subscriber Line (DSL), ISDN, and others.

Free Space Optics is an example of wireless WAN technologies.

The key differentiator of wireless WAN technologies from WLAN, WPAN, and WMAN is that the wireless WAN link aggregates multiple communications channels together (multiplexing) and passes them across the single WAN link.

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Wireless LAN Technology Roles

Corporate Data Access and End-User Mobility

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Wireless LAN Technology Roles

Network Extension to Remote Areas

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Wireless LAN Technology Roles

Building-to-Building Connectivity: Bridging

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Wireless LAN Technology Roles

Last-Mile Data Delivery: Wireless ISP

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Small Office/Home Office (SOHO) Use

Wireless LAN Technology Roles

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Mobile Office Networking

Educational/Classroom Use

Wireless LAN Technology Roles

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Industrial: Warehousing and Manufacturing

Health Care: Hospitals and Offices

Hotspots: Public Network Access

A Wi-Fi hotspot provides wireless Internet access in public areas.

Hospitals can benefit from wireless LAN technology in order to have roaming access to patient records as well as pharmacy information. Medical prescriptions can be sent to the hospital pharmacy directly from the patient’s rooms, and nurses can give instant digital feedback using PDAs as they make their rounds throughout the hospital.

Wireless LAN Technology Roles

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Advantages of WLAN

Mobility is primary advantage of wireless technology

Easier and Less Expensive Installation: Installing network cabling in older buildings difficult and costly

Increased Reliability

– eliminates certain types of cable failures and increases overall network reliability

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Disadvantages of WLAN

Security: Wireless signals broadcast in open air

– Security for wireless LANs is the prime concern

Unauthorized users might access network

Attackers might view transmitted data

Employees could install rogue access points

Attackers could easily crack existing wireless security Radio Signal Interference: Signals from other devices can

disrupt wireless transmissions

Health Risks: Wireless devices emit RF energy

– Not known if or to what extent low levels of RF might cause adverse health effects

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Glossary

FCC The Federal Communications Commission (FCC) is responsible for defining limitations and allowances for radio frequency communications—among other things—in the United States and its territories. They define the regulations that are then implemented in IEEE and other standards.

IEEE The Institute of Electrical and Electronics Engineers specifies standards based on regulations defined by regulatory bodies.

Wi-Fi Alliance An organization that certifies equipment to be interoperable with other equipment in the WLAN industry based on their certification standards.

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Glossary

direct sequence spread spectrum (DSSS) One of the originalPhysical layer technologies specified in the IEEE 802.11 standard that provides instantaneous data rates of 1 or 2 Mbps and operates in the 2.4-GHz frequency band.

HR/DSSS Originally specified in the IEEE 802.11b amendment, the high-rate/direct-sequence spread spectrum Physical layer specifies data rates up to 11 Mbps.

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Review Questions

1. Which of the following organizations is responsible for compatibility testing of 802.11 hardware?

A. IEEE

B. ETSI

C. Wi-Fi Alliance

D. FCC

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Review Questions

2. You want to read the 802.11 standard so that you can better understand the details of the MAC and PHY layer functionality in wireless LANs. Which organization’s web site should you visit?

A. IEEE

B. ETSI

C. Wi-Fi Alliance

D. FCC

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Review Questions

3. Which of the following technologies are not wireless WAN solutions? (Choose all that apply.)

A. Zigbee

B. Free Space Optics

C. Wi-Fi Access Points

D. Bluetooth

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Review Questions

4. What are the two types of wireless bridge links that can be created? (Choose two.)

A. Point-to-point

B. Building-to-building

C. Point-to-multipoint

D. Remote-to-local