About Wireless Standards
Traditionally a connection to the Internet or LAN (local area
network) was established using some kind of physical media such as a LAN
or phone cable. With a wireless network users are liberated from the
dependence on a hard-wired connection. In a location set up for
wireless access there is a anytime/anywhere network connection. A user
with a specially equipped laptop will be able to roam throughout such a
location without losing their network connection. A wireless connection
to the Internet or LAN is exactly the same as a wired one except there
is no physical connection (cable).
802.11 Standard
Much of the recent growth in wireless networks can be attributed to
the adoption of the 802.11 standard. This is a standard for wireless
networks that provides guidelines for the manufacture of wireless
hardware. Wireless hardware that meets the 802.11 standard will be
compatible across different manufacturers. For example a wireless
network card manufactured by 3Com will work with a wireless access point
manufactured by Lucent. Because of this standard there has a been a
significant reduction in the price of wireless hardware which has in
turned helped it to grow.
802.11Subcategories (802.11b / 802.11a / 802.11g)
Toward the end of 1999, the 802.11b standard was ratified by the
IEEE. The 802.11b standard operates in the 2.4 GHz unlicensed ISM
spectrum. Because of abundant industry expertise in building 2.4 GHz
radios for existing products like cordless phones, wireless LAN
products based on 802.11b quickly arrived on the market, offering
Ethernet-class data rates (up to 11 Mbps) and backward compatibility
with the initial 802.11 standard. 802.11b products quickly
penetrated the mass market because they were the first to deliver
acceptable speeds at accessible prices. Furthermore, the Wi-Fi
Alliance (formerly known as the Wireless Ethernet Compatibility
Alliance) began to certify 802.11b products for interoperability
with one another. Because 802.11b was the first technology to meet
the requirements of enterprise LANs, much of the mainstream wireless
infrastructure has been built on it.
- 802.11a
The 802.11a standard delivers data rates of 6-54 Mpbs using
Orthogonal Frequency Division Multiplexing (OFDM) in the 5 GHz
frequency bands. Because of difficulties in developing 5 GHz chips,
802.11a-based products did not become available until late 2001.
This has led to a low level of adoption and relatively high prices.
A major problem is that 802.11a is not compatible with 802.11b.
The cost disadvantage of an 802.11a system is not limited to the
price of the individual components. Because it uses the higher 5 Ghz
bandwidth, 802.11a has a practical range of approximately half that
of 802.11b. Lower range requires the use of more access points to
cover the network geography, adding to the total cost of an 802.11a
system.
- 802.11g
The 802.11g standard can deliver up to 54 Mbps data rates in the 2.4
GHz frequency band. Since both 802.11g and 802.11b operate on the
2.4 GHz frequency band, they are completely interoperable.
Therefore, users can protect the investments they've made in 802.11b
equipment when purchasing compatible 802.11g products. Other
characteristics of 802.11g are:
- High performance that satisfies bandwidth-intensive
applications and areas with many wireless users
- Backward compatibility with the installed base of 802.11b
wireless LANs, reducing upgrade costs
- Lower product costs compared to an 802.11a/b solution,
because only one radio is necessary with 802.11g
- Good range compared to 802.11a, which lessens deployment
costs due to fewer access points in most applications
- A method of prioritizing data packets to improve quality of
streaming media, such as VoIP, voice and video conferencing
- Because of these features, 802.11g is quickly replacing
802.11b as the mainstream wireless LAN technology.
