The term wireless refers to the communication or transmission of information over a distance without requiring wires or cables. The devices used for wireless communication may include cordless telephones, mobiles, GPS units, ZigBee technology, wireless computer parts, satellite television, etc. Wireless Networking technologies connect multiple computers, systems and devices together without requiring wires or cables: a wireless local area network or WLAN comes under Wi-Fi. Most of our discussion would be in wireless LANs and related areas as per the broad objectives of the exam.
802.xx standards:
1. IEEE 802.1 : Standards for LAN/MAN bridging and management and remote media access control (MAC) bridging.
2. IEEE 802.3 describes CSMA/CD Ethernet standard.
3. IEEE 802.4 is a standard for Token bus networks.
4. IEEE 802.5 describes Token Ring networks.
5. IEEE 802.10 : Standards for LAN/MAN security implementations.
6. IEEE 802.11: Standard for wireless LAN.
The following are the important features of 802.11 standard:
1. The 802.11g standard supports data rates up to 54 Mbps, whereas 802.11b supports data rates only up to 11 Mbps.
2. The hardware complying to 802.11g operates at 2.4 GHz range
3. The 802.11g equipment is as susceptible to interference as 802.11b.
4. IEEE 802.11g is compatible with 802.11b, but not compatible with 802.11a, or Bluetooth.
5. 802.11n works in both 2.4GHz, and 5GHz bands. The standard supports up to 600Mbits/sec bandwidths. It is downward compatible with 802.11a, 802.11b, and 802.11g standards.
6. 802.11a, and 802.11g use OFDM (short for Orthogonal Frequency Division Multiplexing). IEEE 802.11b uses DSSS (short for Direct Sequence Spread Spectrum) for encoding.
7. IEEE 802.16 : Wireless Networking - "WiMAX"
The data rates supported by various wireless standards are as given below:
Bluetooth has the lowest data rates (up to 1 Mbps), whereas 802.11ac supports very high data rates.
Important Points to Remember:
802.11 standards are typically used in wireless LAN configurations. Bluetooth supports low speeds up to 1 Mbps over short distances up to a max of 30 feet. The technology is well suited for connecting PDAs or wireless mouse to a computer.
802.11g is compatible with 802.11b. Note that 802.11b is not compatible with either 802.11a or 802.11g. Similarly, 802.11a is not compatible with either 802.11b or 802.11g. Therefore, from compatibility point of view, 802.11g, and 802.11ac have better compatibility.
All Bluetooth, 802.11b, and 802.11g use 2.4GHz spectrum, where as 802.11a uses 5 GHz spectrum. Note that 2.4GHz band is more susceptible to noise compared with 5 GHz because several ISM band compatible devices work in the 2.4GHz frequency band.
IEEE 802.3 defines the MAC layer for bus networks that use CSMA/CD. This is the basis of the Ethernet standard.
Bluetooth is a standard for the short-range wireless interconnection of mobile phones, computers, and other electronic devices.
Rendezvous, based on open Internet Engineering Task Force (IETF), uses standard networking protocols and zero configuration technology to automatically discover and connect devices over any IP network, such as Ethernet or 802.11-based wireless networks like Apple's Airport.
IEEE 802.11x is the standard that pertains to wireless LANs.
802.11ac is called Gigabit Wi-Fi or 5G Wi-Fi.
802.11ac is a 5-GHz only technology that can use wider channels in the 5-GHz band, more spatial streams, and multi-user MIMO (MU-MIMO) as shown in the figure.
Worldwide Interoperability for Microwave Access (WiMAX) is based on 802.16.
Wi-Fi Standards
802.11ax (Wi-F 6): Delivers faster speeds, support more devices simultaneously, decrease latency, improve security, and increase bandwidth. 802.11ax operates in both 2.4 GHz and 5 GHz ranges.
802.11ac(Wi-Fi5 ): Supports 2.4GHz (through 802.11n tech) and 5GHz bands and has speeds up to 1300 Mbps.
802.11ac: Uses dual-band wireless technology, supporting simultaneous connections on both 2.4 GHz and 5 GHz
802.11n (Wi-Fi 4): Uses the 2.4GHz and 5GHz bands and improves speeds up to 600 Mbps.
802.11g(Wi-Fi 3): Combined the best of 802.11a/b to achieved speeds up to 54 Mbps on the 2.4GHz band.
