What is it?
802.11g is a new IEEE standard for wireless LANs that is currently in draft form, and expected to be ratified (finally approved) in July 2003. I'll explain more about the implications of this later. Its key claims to fame are 54Mbps raw data rate and 802.11b backward compatibility.
802.11g's higher speed comes from using the Orthogonal Frequency Division Multiplexing (OFDM) modulation scheme - the same as used in 802.11a. Backward compatibility comes from using the 2.4GHz band, supporting the old Complementary Code Keying (CCK) modulation scheme used by 802.11b, and new "protection" mechanisms described in the 11g draft standard.
802.11g's negatives are the same as 802.11b's, i.e. only three non-overlapping channels and interference from cordless phones and microwave ovens. So if you're having interference problems with your 802.11b network, you'll still have them with 802.11g.
Broadcom's 54g FAQ describes some of the technical details of the draft specification, which includes:
A new physical layer for the 802.11 Medium Access Control (MAC) in the 2.4 GHz frequency band, known as the extended rate PHY (ERP). The ERP adds OFDM as a mandatory new coding scheme for 6, 12 and24 Mbps (mandatory speeds), and 18, 36, 48 and 54 Mbps (optional speeds). The ERP includes the modulation schemes found in 802.11b including CCK for 11 and 5.5 Mbps and Barker code modulation for 2 and 1 Mbps.
- An optional MAC mechanism called RTS/CTS that governs how 802.11g devices and 802.11b devices interoperate. RTS/CTS is also optional in 802.11b.