Wireless network

The workplace continues to evolve beyond the traditional desktop as employees and workgroups become more mobile. When professionals conduct business away from their desktop environment, they lose access to valuable applications, Internet content and communications tools. This separation from the desktop negatively impacts the productivity of teams and individuals.
Why Wireless LANs?
Organizations around the world are installing wireless networks to increase employee productivity. Wireless mobility solutions extend the enterprise by keeping employees connected to the corporate network's applications, content, and communications channels for a larger percentage of each day whether they are at work, at home, or on the road.
WLAN Security Concerns - Is Mobility Secure?
With the increased reliance on Wireless LANs, businesses are becoming more concerned about network security. Network managers need to provide end users with freedom and mobility without offering intruders access to the Wireless LAN or the information sent and received on the wireless network. Fortunately, the security technology is now available to provide privacy of corporate data that rides over all types of networks: private corporate networks, the Internet, and wireless LANs. The IEEE 802.1X standard provides reliable, scalable and centralized security management with mutual authentication and dynamic encryption features to protect the privacy of transmitted data.
Productivity Zone
As employees move away from the desktop their productivity decreases. Businesses can improve employee and workgroup productivity by extending secure, high-speed access to the corporate network while at the workplace via wireless and IP Communications at home via telework, and on the road via secure wireless solutions at hotspots. As businesses add mobility solutions, they extend employees access to the corporate network beyond the desktop, thus increasing employee productivity.
In November 2001, an independent study by NOP World—one of the world's largest research and business information companies— found that WLANs enabled end users to stay connected an additional 1.75 hours each day, resulting in an increase in productivity of up to 22 percent.
Praxis Computing - Your Wireless Networking Experts
Praxis Computing offers expert advice and services as you plan, design, implement, operate, and optimize your wireless network . Our Los Angeles based consultants and engineers have direct experience in all phases of deploying wireless networkinfrastructures. They hold Microsoft and Cisco certifications and have experience with companies ranging from small local firms to global enterprises. With specialized tools and knowledge of the latest wireless networking technology, Praxis computing can gain an in-depth knowledge of your business objectives to assist you in successfully deploying your wireless network.

The new Nokia 6236 gives you cool technology for a great price. The VGA-quality camera takes printable photos as well as short video clips for sharing. There’s also a cool FM stereo radio that’s great when you’ve got a few minutes to yourself. Plus, with voice-activated dialing, a vibrant colorful screen, built-in speakerphone, and downloadable games, ringtones and wallpaper, the Nokia 6236 is a nice phone for not a lot of money.Highlights
VGA-quality camera lets you take and share great pictures
Record video clips and share them with friends
Built-in FM stereo radio
Voice-activated dialing gives you convenient hands-free operation
Vibrant colorful screen displays over 65,000 colors
Large internal memory to store pictures and videos
Convenient built-in speakerphone lets you have a group meeting anywhere you are
Downloadable games, ringtones and wallpapers from Verizon Wireless Get It Now Service What's In The Box With The Phone
Additional Items Included - Battery, Wall Charger, User GuideAdvanced Features
Digital Camera - VGA-quality (640 x 480 Pixel Resolution Max)
Streaming Multimedia Support - Yes, Video Playback Capable
FM Radio - Yes, Stereo
Video Capture / Camcorder - Yes, H.263 Format, Sub-QCIF Resolution (128 x 96 Pixel Resolution Max)
Infrared Port - Yes
Voice-driven Menus - Yes
Data Capable / Use This Phone As A Modem - Yes, Via Infrared Or USB Cable Sold Separately
PC Synchronization - Yes, Via Infrared Or USB Cable Sold SeparatelyMessaging Features
Verizon Wireless Mobile Web 2.0 - Yes
Multimedia Messaging - Yes, TXT/PIX Compatible, Send Picture Slideshows To Other Compatible SMIL Phones
Text Messaging (SMS) - Yes, TXT/PIX Compatible, Pre-created Message TemplatesPersonalization and Fun Features
Polyphonic Ringtones - Yes, 24 Chords, Downloadable From Verizon Wireless Get It Now Service
Custom Ringtones - Yes
MP3 Ringtones - Yes
Ringer Profiles - Yes, MP3 and AAC Formats
Picture Caller ID - Yes
Multiple Languages - Yes
Games - Downloadable From Verizon Wireless Get It Now Service
Customizable Graphics - Downloadable From Verizon Wireless Get It Now ServiceCore Features
Color Main Display - Yes, 128 x 160 Pixels, Over 65,000 Colors Displayed
Speakerphone - Yes
Voice-activated Dialing - Yes
To-Do List - Yes
Voice Memo - Yes
Standard 2.5mm Headset Jack - Yes
Alarm - Yes
Calculator - Yes
Calendar - Yes
Mini-USB Port - Yes
Vibrate - Yes
Multiple Numbers Per Name - YesBattery Life
Battery Type - LiIon
Talk Time - Up to 210 Minutes
Standby Time - Up to 288 HoursTechnical Specifications
Application Platform - BREW
Network Compatibility - CDMA 850, 1900, AMPS 850
Ringtone Types Supported - MP3, AAC, QCELP
Data Download Speed - 1xRTT (Up to 130 Kbps)
Predictive Text Entry - Yes, T9
Built-In Memory - 10MB
Dimensions - 4.15 in x 1.67 in x 0.71 in
Weight - 3.46 ozCompatibility Features
Device Supports Voice Plans - Yes
Available For Purchase Without Service Plan - Yes
Device Supports IN Messaging (TXT-PIX-FLIX) - Yes

Wireless MAN - metropolitan area network
Wireless LAN - local area networks
Wireless PAN - personal area networks
GSM - Global standard for digital mobile communication, common in most countries except South Korea and Japan
PCS - Personal communication system - not a single standard, this covers both CDMA and GSM networks operating at 1900 MHz in North America
Mobitex - pager-based network in the USA and Canada, built by Ericsson, now used by PDAs such as the Palm VII and Research in Motion BlackBerry
GPRS - General Packet Radio Service, upgraded packet-based service within the GSM framework, gives higher data rates and always-on service
UMTS - Universal Mobile Telephone Service (3rd generation cell phone network), based on the W-CDMA radio access network
AX.25 - amateur packet radio
NMT - Nordic Mobile Telephony, analog system originally developed by PTTs in the Nordic countries
AMPS - Advanced Mobile Phone System introduced in the Americas in about 1984.
D-AMPS - Digital AMPS, also known as TDMA
Wi-Fi - Wireless Fidelity, widely used for Wireless LAN, and based on IEEE 802.11 standards.
Wimax - A solution for BWA (Broadband Wireless Access) and conforms to IEEE 802.16 standard.

Wireless networks are based on the IEEE 802.11 standards. A basic wireless network consists of multiple stations communicating with radios that broadcast in either the 2.4GHz or 5GHz band (though this varies according to the locale and is also changing to enable communication in the 2.3Ghz and 4.9Ghz ranges).
802.11 networks are organized in two ways: in a BSS one station acts as a master with all the other stations associating to it; this is termed infrastructure mode and the master station is termed an access point (AP). In BSS mode all communication passes through the AP; even when one station wants to communicate with another wireless station messages must go through the AP. In the second form of network there is no master and stations communicate directly. This form of network is termed an IBSS and is commonly know as an adhoc network.
802.11 networks were first created in the 2.4GHz band using protocols defined by the IEEE 802.11b standard. These specifications include the operating frequencies, MAC layer characteristics including framing and transmission rates (communication can be done at various rates). Later the 802.11a standard defined operation in the 5GHz band, including different signalling mechanisms and higher transmission rates. Still later the 802.11g standard was defined to enable use of 802.11a signalling and transmission mechanisms in the 2.4GHz band in such a way as to be backwards compatible with 802.11b networks.
Separate from the underlying transmission techniques 802.11 networks have a variety of security mechanisms. The original 802.11 specifications defined a simple security protocol called WEP. This protocol uses a fixed pre-shared key and the RC4 cryptographic cipher to encode data transmitted on a network. Stations must all agree on the identity of the fixed key in order to communmicate. This scheme was shown to be easily broken and is now rarely used except to discourage transient users from joining networks. Current security practice is given by the IEEE 802.11i specification which defines new cryptographic ciphers and an additional protocol to authenticate stations to an access point and exchange keys for doing data communication. Further, cryptographic keys are periodically refreshed and there are mechanisms for detecting intrusion attempts (and for countering intrusion attempts). Another security protocol specification commonly used in wireless networks is termed WPA. This was a precursor to 802.11i defined by an industry group as an interim measure while waiting for 802.11i to be ratified. WPA specifies a subset of the requirements found in 802.11i and is designed for implementation on legacy hardware. Specifically WPA defines the TKIP protocol that is derived from the original WEP protocol. 802.11i permits use of TKIP but most stations will instead use the AES cipher for encrypting data; a cipher that is too computationally costly to be implemented on legacy hardware.
Other than the above protocol standards the other important standard to be aware of is 802.11e. This defines protocols for deploying multi-media applications such as streaming video and voice over IP (VoIP) in an 802.11 network. Like 802.11i, 802.11e also has a precursor specification termed WME (and now WMM) that has been defined by an industry group as a subset of 802.11e that can be implemented now to enable multi-media applications while waiting for the final ratification of 802.11e. The most important thing to understand about 802.11e and WME/WMM is that it enables prioritized traffic use of a wireless network through Quality of Service (QoS) protocols and enhanced media access protocols. Proper implementation of these protocols enable high speed bursting of data and prioritized traffic flow.
FreeBSD 6.0 supports networks that operate using 802.11a, 80.211b, and 802.11g. The WPA and 802.11i security protocols are likewise supported (in conjunction with any of 11a, 11b, and 11g) and QoS and traffic prioritization required by the WME/WMM protocols are supported for a limited set of wireless devices.

WLAN is expected to continue to be an important form of connection in many business areas. The market is expected to grow as the benefits of WLAN are recognized. Frost & Sullivan estimate the WLAN market to have been 0.3 billion US dollars in 1998 and 1.6 billion dollars in 2005. So far WLANs have been installed in universities, airports, and other major public places. Decreasing costs of WLAN equipment has also brought it to many homes. However, in the UK the exorbitant cost of using such connections in public has so far limited use to airports' Business Class lounges, etc. Large future markets are estimated to be in health care, corporate offices and the downtown area of major cities. New York City has even begun a pilot program to cover all five boroughs of the city with wireless internet.
Originally WLAN hardware was so expensive that it was only used as an alternative to cabled LAN in places where cabling was difficult or impossible. Such places could be old protected buildings or classrooms, although the restricted range of the 802.11b (typically 30 ft.) limits its use to smaller buildings. WLAN components are now cheap enough to be used in the home, with many being set-up so that one PC (a parent's PC, for example) can be used to share an internet connection with the whole family (whilst retaining access control at the parents' PC).
Early development included industry-specific solutions and proprietary protocols, but at the end of the 1990s these were replaced by standards, primarily the various versions of IEEE 802.11 (Wi-Fi) (see separate articles) and HomeRF (2 Mbit/s, intended for home use, unknown in the UK). An alternative ATM-like 5 GHz standardized technology, HIPERLAN, has so far not succeeded in the market, and with the release of the faster 54 Mbit/s 802.11a (5 GHz) and 802.11g (2.4 GHz) standards, almost certainly never will.

From en.wikipedia.org