Wi Fi : The IEEE 802.11 Standards
The IEEE (Institute of Electrical and Electronic Engineers) released the 802.11 specifications in June 1999. The initial specification, known as 802.11. In late 1999, two new addenda were released. The 802.11b specification increased the performance to 11 Mbps in the 2.4 GHz range while the 802.11a specification utilized the 5 GHz range and supported up to 54 Mbps.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.
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 operated in the 2.4 GHz range and was the original specification of the 802.11 IEEE standards.
- Data rates commonly in the 1 to 2 Mbps range.
- 802.11a uses the 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- This specification is no longer used and has largely been replaced by other forms of the 802.11 standard.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 operates in the 5 - 6 GHz
- Data rates commonly in the 6 Mbps, 12 Mbps, or 24 Mbps range.
802.11a uses the orthogonal frequency division multiplexing (OFDM) standard, so 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.
- 802.11a specification is also known as Wi-Fi5.
- The 802.11b standard (also known as Wi-Fi) operates in the 2.4 GHz range.
- Data rates commonly are in the 11 Mbps range.
- It is backward compatible with the 802.11 standard.
- 802.11b uses a technology known as complementary code keying (CCK) modulation
- (CCK) modulation allows higher data rates with less chance of multi-path propagation interference.
- 802.11g operates in the 2.4 GHz range.
- 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 wireless networking products.
- 802.11g offers the best features of both 802.11a and 802.11b.
- This standard has not yet been certified, and therefore is unavailable.
- Additional extensions have been developed for both IEEE 802.11a and / or IEEE 802.11b to address European regulation needs and advanced MAC specifications such as authentication, Quality of Service (QoS), and encryption. Shown in figure5.1