Unfortunately, the two new specifications were incompatible because they used different frequencies. This means that 802.11a network interface cards (NICs) and access points cannot communicate with 802.11b NICs and
access points. This incompatibility forced the creation of the new draft standard known as 802.11g. 802.11g supports up to 54 Mbps and is interoperable with 802.11b products on the market today. The concern is that the 802.11g specification is currently in development and products will not be available until a later date.
802.11 Specifications
The 802.11 specifications were developed specifically for Wireless Local Area Networks (WLANs) by the IEEE and include four subsets of Ethernet-based protocol standards: 802.11, 802.11a, 802.11b, and 802.11g.
802.11
802.11 operated in the 2.4 GHz range and was the original specification of the 802.11 IEEE standard. This specification delivered 1 to 2 Mbps using a technology known as phase-shift keying (PSK) modulation. This specification is no longer used and has largely been replaced by other forms of the 802.11 standard.
802.11a
802.11a operates in the 5 - 6 GHz range with data rates commonly in the 6 Mbps, 12 Mbps, or 24 Mbps range. Because 802.11a uses the orthogonal frequency division multiplexing (OFDM) standard, data transfer rates can be as high as 54 Mbps. OFDM breaks up fast serial information signals into several slower sub-signals that are transferred at the same time via different frequencies, providing more resistance to radio frequency interference. The 802.11a specification is also known as Wi-Fi5, and though regionally deployed, it is not a global standard like 802.11b.
802.11b
The 802.11b standard (also known as Wi-Fi) operates in the 2.4 GHz range with up to 11 Mbps data rates and is backward compatible with the 802.11 standard. 802.11b uses a technology known as complementary code keying (CCK) modulation, which allows for higher data rates with less chance of multi-path propagation interference (duplicate signals bouncing off walls).
U.S. Robotics 22 Mbps 802.11b
Recent developments to 802.11b have seen numerous improvements to this well-established and widely-deployed wireless standard. New U.S. Robotics 22 Mbps products are designed to support Packet Binary Convolutional Coding (PBCC) in addition to CCK modulation. This not only increases performance but also
maintains complete 802.11b compatibility with both 11 Mbps and 22 Mbps products. The overall benefits include:
- Up to twice the data rate of conventional 11 Mbps 802.11b standard products.
- Greater WLAN coverage: up to 70% greater than standard 11 Mbps 802.11b products.
- Full interoperability with all 802.11b products: works with 802.11b 11 Mbps, 802.11b 22 Mbps, and upcoming 802.11g products.
- Improved security over standard 802.11b: 256-bit WEP encryption and MAC address authentication*.
802.11g is the most recent IEEE 802.11 draft standard and operates in the 2.4 GHz range with data rates as high as 54 Mbps over a limited distance. It is also backward compatible with 802.11b and will work with both 11 and 22 Mbps U.S. Robotics wireless networking products. 802.11g offers the best features of both 802.11a and 802.11b, but as of the publication date of this document, this standard has not yet been certified, and therefore is unavailable.