Wireless Networks Standards and Protocols

& x Standards and x refers to a family of specifications developed by the IEEE for wireless LAN (WLAN) technology specifies an over-the-air interface between a wireless client and a base station or between two wireless clients. The IEEE accepted the specification in 1997.

standards in the OSI model

There are several specifications in the family: — applies to wireless LANs and provides 1 or 2 Mbps transmission in the 2.4 GHz band using either frequency hopping spread spectrum (FHSS) or direct sequence spread spectrum (DSSS) a a — an extension to that applies to wireless LANs and provides up to 54-Mbps in the 5GHz band a uses an orthogonal frequency division multiplexing encoding scheme rather than FHSS or DSSS b b (also referred to as High Rate or Wi-Fi) — an extension to that applies to wireless LANS and provides 11 Mbps transmission (with a fallback to 5.5, 2 and 1-Mbps) in the 2.4 GHz band b uses only DSSS b was a 1999 ratification to the original standard, allowing wireless functionality comparable to Ethernet.

DSSS & FHSS direct sequence spread spectrum (DSSS In direct sequence spread spectrum (DSSS), the stream of information to be transmitted is divided into small pieces, each of which is allocated across to a frequency channel across the spectrum. A data signal at the point of transmission is combined with a higher data-rate bit sequence (also known as a chipping code) that divides the data according to a spreading ratio. The redundant chipping code helps the signal resist interference and also enables the original data to be recovered if data bits are damaged during transmission. Frequency hopping Frequency hopping is one of two basic modulation techniques used in spread spectrum signal transmission. It is the repeated switching of frequencies during radio transmission, often to minimize the effectiveness of "electronic warfare" - that is, the unauthorized interception or jamming of telecommunications. It also is known as frequency- hopping code division multiple access (FH-CDMA). Frequency hopping requires a much wider bandwidth than is needed to transmit the same information using only one carrier frequency.

DSSS & FHSS

802.11e e — a wireless draft standard that defines the Quality of Service (QoS) support for LANs, and is an enhancement to the a and b wireless LAN (WLAN) specifications e adds QoS features and multimedia support to the existing IEEE b and IEEE a wireless standards, while maintaining full backward compatibility with these standards g g — applies to wireless LANs and is used for transmission over short distances at up to 54-Mbps in the 2.4 GHz bands n MIMO n — n builds upon previous standards by adding multiple-input multiple-output (MIMO). The additional transmitter and receiver antennas allow for increased data throughput through spatial multiplexing and increased range by exploiting the spatial diversity through coding schemes like Alamouti coding. The real speed would be 100 Mbit/s (even 250 Mbit/s in PHY level), and so up to 4-5 times faster than g.

Wireless Protocols

WEP WEP - Wired Equivalent Privacy ◦Short for Wired Equivalent Privacy, a security protocol for wireless local area networks (WLANs) defined in the b standard.

WAP WAP - Wireless Application Protocol ◦A secure specification that allows users to access information instantly via handheld wireless devices such as mobile phones.

WEP vs. WAP The Differences Between WEP and WPA ◦WPA has been a mainstream technology for years now, but WEP remains a standard feature on virtually every wireless router on store shelves today.  When using a wireless access point or router it is important to remember that if you can send information from one device and receive it at another, anyone else within range might also be able to receive it. When protecting data send via wireless, security and protection is offered through encryption schemes that come with your wireless hardware you can enable.

WEP vs. WAP WEP's Major Weakness ◦WEP's major weakness is its use of static encryption keys. When you set up a router with a WEP encryption key, that one key is used by every device on your network to encrypt every packet that's transmitted. But the fact that packets are encrypted doesn't prevent them from being intercepted, and due to some esoteric technical flaws it's entirely possible for an eavesdropper to intercept enough WEP- encrypted packets to eventually deduce what the key is.

WEP vs. WAP Wi-Fi Protected Access (WPA) Address WEP's Shortcomings ◦WPA aims to provide stronger wireless data encryption than WEP, but not everyone has or was able to jump onboard with the new wireless encryption technology. In order to use WPA all devices on the network must be configured for WPA. ◦If a device is not configured for WPA, it will usually fall back to the lesser WEP encryption scheme, enabling the wireless devices to communicate on the network. The technology was designed to work with existing Wi-Fi products that have been enabled with WEP (i.e., as a software upgrade to existing hardware), but the technology includes two improvements over WEP: temporal key integrity protocol  Improved data encryption through the temporal key integrity protocol (TKIP). TKIP scrambles the keys using a hashing algorithm and, by adding an integrity-checking feature, ensures that the keys haven't been tampered with. extensible authentication protocol  User authentication, which is generally missing in WEP, through the extensible authentication protocol (EAP). WEP regulates access to a wireless network based on a computer's hardware-specific MAC address, which is relatively simple to be sniffed out and stolen. EAP is built on a more secure public-key encryption system to ensure that only authorized network users can access the network.