Wireless Fidelity (Wi-Fi) allows you the freedom to connect to the Internet at high speed without wires. Wi-Fi technology works just like a cordless phone, transmitting a wireless signal from a base station to a device in the 2.4 GHz and 5 GHz radio bands. Wi-Fi-enabled devices are designed to transmit data across a wireless network at broadband speeds.
A Wi-Fi network works through base stations called access points, which connect to high-speed lines back into the data network and the Internet. Many newer laptop computers and PDAs are equipped with built-in Wi-Fi antennas and software. As a result, selecting a few settings in the Wi-Fi software lets you connect using a Wi-Fi data signal. In fact, most Wi-Fi software is set up to find and display the Wi-Fi signals available in your location.
While Wi-Fi is designed to transmit data over the wireless portion of the network connection at speeds well into the megabit range, the ultimate speed of the connection you receive on your Wi-Fi device is governed by many factors, including the number of active users using a single access point, the device's distance from the access point, any obstructions that are blocking the signal, the model of Wi-Fi card and software you are using on your device, and the speed of the wired line that connects to the access point.
Generally, Wi-Fi signals transmit reasonably well through glass and gypsum board, but not well through metal or concrete buildings, water, or people—since we tend to be mostly water.
A Wi-Fi access point location that is available in a public location (away from your home or office) is commonly called a HotSpot. Typically, a HotSpot has a limited range of service—up to 300 feet (150-foot radius) with no obstructions for a single access point. But by using multiple access points, the range of service can be extended to cover almost any size area. Many business owners are using multiple access points to attract patrons to their "Hot Destinations."
It is important to remember that the network only maintains a given data rate as long as the access point and client maintain a strong connection. Translation: the closer the client is to the access point, the more likely the ability to communicate at the network's maximum data rate. And the bandwidth of the wireless network is shared among all the clients.
Whenever you communicate over the Internet using a wired or wireless connection, there is a certain level of security risk. Unless you connect to your office network through a Virtual Private Network (VPN), hackers may try to intercept your e-mails, files, and data, or use your Internet connection to distribute their own messages. VPN software provides an encrypted tunnel through the Internet to and from the destination server or database. If you are not familiar with the term, you probably do not have a VPN. So, only use Wi-Fi when you are Web surfing to avoid sending confidential or sensitive information.
The three flavors of Wi-Fi
While 802.11b is more than enough bandwidth for single-user clients at 11 Mbits/sec, file sharing between multiple clients or large file transfers will be unacceptably slow to users who are accustomed to wired LAN speeds.
But there are two other choices that offer up to five times the raw data rate, at 54 Mbits/sec:
802.11g, which operates within the same 2.4 GHz frequency band and is backward-compatible with 80.211b; and 802.11a, which operates in the 5 GHz band but is not compatible with 802.11b or g.
While 802.11a offers less operating range (25- to 75-foot radius) than 802.11b and 802.11g (up to 150-foot radius), it has up to 12 non-overlapping channels, compared to three for 802.11b and 802.11g. Translation: 802.11a can handle far more traffic.
The combination of short operating range and capability for handling high-volume traffic makes 802.11a a great choice for high-bandwidth applications like streaming media, or small high-traffic areas like crowded conference rooms.
Today, the fastest-growing wireless LAN technology is 802.11g. More and more computer manufacturers are offering laptops with built-in, dual-band 802.11a/g capability. Because of its longer operating range and backward compatibility with 802.11b, 802.11g is the best choice for larger areas and for legacy equipment in Internet cafes or HotSpots.
Does this mean that 802.11b will disappear? Not likely. 802.11b is great for mobile devices like phones and personal digital assistants that require low-bandwidth connectivity for such applications as voice, e-mail, text messaging, and calendar management.
The standards
In the beginning —like about five or so years ago—there was only the IEEE 802.11 standard for wireless. But now, the list is a bit overwhelming:
- 802.11a describes wireless networking using the 5 GHz band that supports data-transfer rates up to 54 Mbits/sec.
- 802.11b describes wireless networking using the 2.4 GHz band that supports data-transfer rates up to 11 Mbits/sec.
- 802.11dexpands 802.11 definitions to allow operation in more countries.
- 802.11ewill improve the quality of service for multimedia applications over wireless networks by adding the ability to give priority to voice or video traffic. A release is expected this year.
- 802.11fdescribes recommended practices that ensure interoperability between equipment from various vendors.
- 802.11gdescribes wireless networking using the 2.4 GHz band, supports data-transfer rates up to 54 Mbits/sec, and is backward-compatible with 802.11b.
- 802.11h provides for band selection within the 5 GHz range and other frequency-management features essential for operation within the European Union.
- 802.11i. will provide enhanced security for wireless network transmissions, using Advanced Encryption Standard (AES). A release is expected this year.
- 802.11k will provide methods for wireless network hardware to measure and report on radio resources, such as interference and signal strength. A 2005 release is expected.
- 802.11n will create networks equivalent to 100Base-T wired Ethernet network connection. A 2006 release is expected.
- 802.16a/WiMAX will describe a fixed broadband wireless network designed with a theoretical range of 50 kilometers (km) and data rate up to 280 Mbits/sec. A release is expected this year.
- 802.16e will describe a mobile broadband version of WiMAX that will enable connections between moving access points. A 2006 release is expected.
- 802.20/MBWA will describe a Mobile Broadband Wireless Access system that will support mobility for vehicles moving up to 155 MPH within a 15-km range, at a transmission rate of 1 Mbit/sec or better. A 2005 release is expected.
- 802.15.3a/UWB will describe an ultrawideband, short-range, high-speed system using a range of frequencies, which could be used to replace cables in home entertainment and computing products. A 2005 release is expected.
- Bluetooth 1.2 will be an improved version of Bluetooth that adds adaptive frequency-hopping to reduce interference, improve voice quality, and speed linking between devices. A release is expected this year.
- LWAPP lets multiple Wi-Fi access points be managed by central servers, thus avoiding having to make configuration changes at each device.
- MIMO (Multiple Input Multiple Output) is a technology that uses an array of antennas and adaptive modulation to improve throughput and reception.
- WPA is an improved security system for Wi-Fi networks, using user authentication and dynamic keys. It will be replaced by 802.11i.
The Get IEEE 802 program makes IEEE 802 standards available at no charge in PDF format after they have been published in PDF for six months. To download available documents, see http://standards.ieee.org/getieee802.
Wireless networking is an evolving technology, and new standards are constantly being developed to address the call for additional features. It will require due diligence on your part to stay informed.
Donna Ballast is BICSI's standards representative, and a BICSI registered communications distribution designer (RCDD). Send your questions to Donna via e-mail: [email protected]