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BuildOrBuy Group Network
www.buildorbuy.org | www.buildorbuy.net ]

BuildOrBuy News - Wireless Topologies:
  1. Network Protocols:
  2. ../images/bullet2.gifWhen considering anything wireless, think Security first! 
  3. Transfer Rate Specs: Data Rates & Throughputs. 
  4. WPA - Wi-Fi Protected Access:
  1. ../images/bullet2.gifHoustonWireless IEEE Standards:

  2. ../images/bullet2.gifIEEE Standards Association:

  3. ../images/bullet2.gifIEEE P802.11, The Working Group for Wireless LANs:

IEEE 802.11 is a shared, Wireless Local Area Network (LAN) Standard including 80211b, 80211a, 80211g, 80211i (enhanced security), 80211h (spectrum and power control management) & 80211e (QoS - Quality of Service).

"The 802.11 Wireless LAN Standard defines Authentication and Encryption Services based on the Wired Equivalent Privacy (WEP) algorithm. The lack of a WEP Key Management Protocol is a principal limitation to providing 802.11 Security." www.Microsoft.com

Hence WPA - Wi-Fi Protected Access released in March 2003.

 

Physical Layer Terminologies:

A variety of radio transmission methods continuously changing frequencies or signal patterns.

  1. FHSS - (Frequency Hopping Spread Spectrum):  Continuously changes center frequency of a conventional carrier several times per second according to a pseudo-random set of channels, while chirp spread spectrum changes the carrier frequency. Because a fixed frequency is not used, illegal monitoring of spread spectrum signals is extremely difficult, if not downright impossible depending on the particular method.
  2. DSSS - (Direct Sequence Spread Spectrum): Used in CDMA, multiplies Data Bits by a very fast pseudo-random bit pattern (PN sequence) and "spreads" Data into a large coded stream taking full bandwidth of the channel. Used by the original IEEE 80211 Wireless Standard. 
  3. OFDM -  (Orthogonal Frequency Division Multiplexing): This Spread Spectrum technique distributes data over a large number of carriers spaced apart at precise frequencies. This spacing provides the "orthogonality" in this technique thus preventing the demodulators from seeing frequencies other than their own.
  4. CCK-OFDM - (Complementary Code Keying-Orthogonal Frequency Division Multiplexing): CCK works only in conjunction with the DSSS and not FHSS. CCK applies sophisticated mathematical formulas to the DSSS codes, permitting the codes to represent a greater volume of information per clock cycle. Technology by www.Intersil.com 
  5. PBCC - (Packet Binary Convolutional Coding): Technology by www.Ti.com
 

Bluetooth

80211b

80211a

80211g

HyperLAN2

HomeRF

Data Rate:

1Mbps

11Mbps

54Mbps

54Mbps

54Mbps

1,2,10Mbps

Physical Layer:

FHSS

CCK

OFDM

CCK, OFDM

OFDM

FHSS

Freq Band:

2.4GHz

2.4GHz

5.0GHz

2.4GHz

5.0GHz

2.4GHz

Usage:

Personal Area Network

Office, SOHO LAN

Office, SOHO LAN

Office, SOHO LAN

Office, SOHO LAN

SOHO LAN

Device Type:

PC's, PDA, Pager & Devices

PC's, PDA, Pager, Devices & Internet Gateway

PC's, PDA, Pager, Devices & Internet Gateway

PC's, PDA, Pager, Devices & Internet Gateway

PC's, PDA, Pager, Devices & Internet Gateway

PC's, PDA, Pager, Devices & Internet Gateway

Range:

30 feet

50 to 300 feet

50 to 300 feet

 

50 to 300 feet

150 feet

Asset:

Pervasive PAN - Personal Area Network

Based on EtherNet

More Channel & Reliability

Backwards compatible with 80211b.

QoS for Voice over Video

Voice plus Data. Lower cost than 802.11

 

Copyright 1992, 1994, 1995-97, 2000-2008, BuildOrBuy Group Network News!
Web Development, Gill Boyd & Team - Posted 10/07/2003; Updated 04/26/2008