IEEE 802.11g

- an overview or tutorial about the 802.11g Wi-Fi standard providing 54 Mbps data transfer rates at 2.4 GHz

This IEEE 802.11 standard for WLANs tutorial is split into several pages each of which addresses different aspects of IEE 802.11 / Wi-Fi operation and technology:

After the introduction of Wi-Fi with the 802.11a and 802.11b standards, the 802.11b standard became the most popular operating in the 2.4 GHz ISM band. This standard proved to be the most popular despite the faster operating speed of the a variant of the standard because the cost of producing chips to operate at 2.4 GHz were much less than ones to run at 5 GHz.

In order to provide the higher speeds of 802.11a while operating on the 2.4 GHz ISM band, a new standard was introduced. Known as 802.11g, it soon took over from the b standard. Even before the standard was ratified, 802.11g products were available on the market, and before long it became the dominant Wi-Fi technology.

With the possible of interoperability with 802.11b, the 802.11g standard soon took off, offering a higher level of performance than its predecessor.

802.11g specifications

The 802.11g standard provided a number of improvements over the 802.11b standard which was its predecessor. The highlights of its performance are given in the table below.

802.11g operation

Like 802.11b, its predecessor, 802.11g operates in the 2.4 GHz ISM band. It provides a maximum raw data throughput of 54 Mbps, although this translates to a real maximum throughput of just over 24 Mbps.

Although the system is compatible with 802.11b, the presence of an 802.11b participant in a network significantly reduces the speed of a net. In fact it was compatibility issues that took up much of the working time of the IEEE 802.11g committee.

A variety of modulation schemes can be sued by 802.11g. For speeds of 6, 9, 12, 18, 24, 36, 48, and 54 Mbps Orthogonal frequency Division Multiplexing (OFDM) is used, but for 5.5 and 11 Mbps it uses Complementary Code Keying (CCK), and then for 1 and 2 Mbps it uses DBPSK/DQPSK+DSSS.

The maximum range that can be achieved by 802.11g devices is slightly greater than that of those using 802.11b, but the range at which the full 54 Mbps can be achieved is much shorter than the maximum range of an 802.11 device. Only when signal levels and interference levels are low can the maximum specified performance be achieved.

Further pages from this tutorial
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