Wireless Networking - 2

Wireless Networking - 2

Summary on What we have Studied in last Tutorial :-

• Wireless technologies allow one or more devices to communicate with each other without any physical connections such as cables.
• Wireless networking allows you to establish a communication between two or more computers. The communication is established using radio frequency (RF) and without the use of cables.
• Wired Networking requires cables to be connected to each and every computer in the network. It becomes difficult to run cables through walls and under the floor making it time consuming.
• Wireless Network can be configured in two ways: Ad hoc or infrastructure mode.
• Reliability of wireless network is less as compared to wired network. The main concern in wireless networks is interference from appliances using same frequency spectrum. However, with the proper installation the interference can be minimized.
• The different wireless standards that are used in wireless networking are IEEE 802.11, Bluetooth, HomeRF, and IrDA. 
• 802.11 is a standard created by Institute of Electrical and Electronic Engineers (IEEE) for defining all aspects of Radio Frequency Wireless Networking. 
• The most widely used adopted wireless networking type is Wireless Fidelity. i.e. Wi-Fi. The difference different standards certified by Wi-Fi are 802.11b, 802.11g and 802.11n.

(2) Different types of IEEE Standards :-

• IEEE 802.11 : Released in year 1997, this is the original version of 802.11 standard. It has a typical data rate of 1Mbps and maximum of 2Mbps in the 2.4 GHz band. The data is transmitted via frequency Hopping Spread Spectrum (FHSS) for 1 Mbps or Direct-sequence Spread Spectrum (DSSS) for 1 and 2 Mbps. The medium access method used in Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA). The security protocol used here is Wired Equivalent Privacy (WEP) and Wi-Fi Protected Access (WPA). WPA is a Wi-Fi standard has improved security features as compared to WEP. It can cover a distance up to 150 feet (approximately 46 meters ).
• IEEE 802.11a : Modified in the year 1999. this is the improved version of the original 802.11 standard. The 802.11a standard operates in the 5 GHz band and uses 52-subcarrier orthogonal frequency-division multiplexing (OFDM) for signal generation. It has a typical data rate of 6Mbps and a maximum data rate of 54Mbps. One of the advantages of using 802.11a is less interference as the operating range in 5 GHz and most of wireless device operate in the 2.4 GHz range. The disadvantage of 802.11a is that it is limited to only line of sight applications due to high carrier frequency and they also cannot penetrate the network as far as 802.11b standard is concerned. The security protocol used is Wired Equivalent Privacy (WEP) and Wi-Fi protected Access (WPA). The maximum range of 802.11a is 50 Meters at the lowest speed, but range is less than 25 meters at higher speeds. The data is transmitted through DSSS and it is not used widely now a days.
• IEEE 802.11b : This standard was also released in 1999. It has typical data rate of 6.5 Mbps and a maximum data rate of 11 Mbps in the 2.4 GHz band. The media access method used here is also Carrier Sense Multiple Access with collision Avoidance (CSMA/CA). IEEE 802.11b uses Direct-Sequence Spread Spectrum (DSSS). The typical indoor range is 30 m at 11Mbps and 90 m at 1Mbps. The security protocol used here is also Wired Equivalent Privacy (WEP) and Wi-Fi Protected Access (WPA). The data is less susceptible to errors due to interference and signal attenuation because the lower data rate use less complex and more redundant methods of Encoding the data.
• IEEE 802.11g : This standard was released in June 2003. It has a typical data rate 0f 22Mbps and maximum data rate 54Mbps in a 2.4 GHz band. The indoor range is 30 m. The security protocol used here is also Wired Equvalent Privacy (WEP) and Wi-Fi Protected Access (WPA). Microwave Ovens, Bluetooth Device and cordless telephones are the device that operate in 2.4 GHz range. Hence, 802.11g suffers interference problem due to lots devices in the 2.4 GHz range. It can cover a distance upto 300 feet (approx. 91 meters). It is backward compatible with 802.11b.
• IEEE 802.11n : This is the latest version of IEEE 802.11 standard. It has typical data rate 300 Mbps and a maximum data rate of 600 Mbps in the 2.4 or 5 GHZ frequency band. 802.11n should be upto 100 times faster than 802.11b and 10 times faster than 802.11a or 802.11g. It also offers better operating distance than the current existing networks. Orthogonal frequency-Division Multiplexing (OFDM) is the modulation scheme used here and security protocol also is Wired Equivalent Privacy (WEP) and Wi-Fi Protected Access (WPA). 802.11n is built on the existing 802.11 standards with an added feature of Multiple-Input Multiple-Output (MIMO). MIMO uses multiple transmitter and receiver antennas for increase data throughput.
• IEEE 802.16 : WiMax is a Wireless Digital Communication System also known as IEEE 802.16, which is intended for Wireless Metropolitan Area Networks. WiMax can provide Broadband access (BWA) upto 30 miles (50 kilometer) for fixed stations, and 3-10 miles (5-15 kilometers) for mobile sations. In contrast, the Wi-Fi/802.11 wireless local area network standard is limited in most cases to only 100-300 feet (30-100 meter ). With Wimax, Wi-Fi like data rates are easily supported, but the issues of interference is less. WiMAX operates on both license and non-license frequencies, providing a regulated environment and viable economic model for wireless carriers.

       WiMax can be used for wireless networking in much the same way as the more common Wi-Fi protocol. WiMax is the second-Generation Protocol that allows for more efficient bandwidth use, Interfernce avoidance, and is intended to allow higher data rates over longer distances. 

The table given below is to summarise the 802.11 standards :

IEEE 802.11 Standards

Wireless Networking -1

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