About definition of 802.11 and Frames
802.11 and Frames
The 802.11 is a global standard that is used to describe the attributes of the wireless local area network. The term WIFI is commonly used to make sure that there is compatibility in the hardware devices that apply the 802.11 standard.
The 802.11 standard reserves the bottom layer of the OSI model for wireless connection that applies the electromagnetic waves (Gast, 2002). For instance the physical layer that provides three forms of information encoding and the data link layer composed of two sub-layers: there is the Logical Link Control and the Media Access Control also known as MAC.
The physical layer describes the radio wave modulation and signaling features for data transmission while data link layer describes the connection between machine bus and physical layer, precisely an access mode that is close what is applied in Ethernet standard and policies for communication in the several stations within the network. The 802.11 standard is composed of three physical layers that describe the alternative forms of transmission:
Data Link Layer
(MAC) 802.2 802.11 Physical Layer
(PHY) DSSS FHSS Infrared
The 802.11 standard is latest standard that allows 1-2 Mbps of bandwidth. The original standard has been developed to optimize bandwidth, for instance 802.11a, 802.11b and 802.11g standards also known as the 802.11 physical standards. The development enables a better specification of the components so as make sure that the security is enhanced or compatible. The following describes the varied 802.11 standards.
The 802.11a standard makes it possible to have higher bandwidth of 54 Mbps. The standard offers 8 channels of 5 GHz in frequency.
The 802.11b is the most used standard and provides optimum bandwidth of 11 Mbps that go up to 300 meters. It applies 2.4 GHz in frequency with 3 channels.
The 802.11c is standard that is considered of interest to the public. It is an advanced model of the 802.1d standard that brings 802.1d bridge using 802.11 compatible devices on the data link.
The 802.11d is a standard that supplements the 802.11 standard so as to make it possible for global application of local 802.11 networks(Gast, 2002). It allows varied devices to exchange information about frequency with regard to what is allowed in the state of origin of device.
The 802.11e standard is supposed to elevate the quality of service at the data link level. The main objective is to describe the needs of the varied packets in regard to bandwidth and transmission delay for it to bring about improved transmission of voice and video.
The 802.11f is a standard that is meant for access point vendors that accept products for compatibility. It applies the Inter-Access Point Roaming Protocol that makes it possible for users that roam to switch as they roam.
The 802.11g is a standard that provides great bandwidth of 54 Mbps on the 2.4 GHz frequency range. It is backwards-compatible with the b standard, hence stating that the devices that back this standard may be compatible with the 802.11b standard.
The 802.11h is targeted at integrating the 802.11 and the European standard while laying reference to the European regulations connected to frequency and energy efficiency.
The 802.11i this standard is supposed to elevate the security of information change. It is grounded on the AES and is able to encrypt transmissions that use the 802.11a, b and g.
The 802.11a, 802.11b and 802.11g standards are physical standards that are interfaced with the 802.11 standard and provide varied modes of operation that allows them to transfer speeds with regard to their range.
Standard Frequency Speed Range WiFi a (802.11a) 5 GHz 54 Mbit/s 10 m WiFi B (802.11b) 2.4 GHz 11 Mbit/s 100 m WiFi G (802.11b) 2.4 GHz 54 Mbit/s 100 m
The 802.11a standard has flow of 54 Mbps and uses the OFDM technology. It sends data in the frequency of 5GHz and applies 8 channles that do not overlap. It is due to this that they are not compatible with the 802.11b devices. They on the other hand use 802.11 a and b chips known as dual band devices. A range of 10 to 70 have speeds of 54 to 6 Mbits/s respectively. The 802.11b has a speed of 11 Mbps of range 100m internally and 200 externally. While the 802.11g has a data sped of 54 Mbps is range comparable to the 802.11b. This standard applies the 2.4 GHz frequency with OFDM coding it is compatible with the 802.11b devices excluding older devices.
The 802.11 standard describes a number of frames that stations like NICs and access points, apply for communications, in addition to the management of wireless links. Each and every frame has a control field that follows the 802.11 protocol model, frame type and indicators for instance if the WEP is working or not among others. Moreover, all of the frames have MAC addresses of the source and destination points, a frame sequence number, frame body and sequence (so as to detect errors).
The 802.11 data frames have protocols and data from great levels in the body of the frame. A data frame is able to use the HTML code from the web page, other frames that are applied for management and control to carry precise information about the wireless links in the body of the frame.
Data frames are known as the pack horses of the 802.11 standard that hauls data from one point to another. The control frames on the other hand are applied in connection with data frames so as to undertake area clearance operations, channel acquisition, carrier-sensing maintenance tasks and positive acknowledgement of acquired data (Gast, 2002). There are also management frames that undertake supervisory duties like integrating and leaving wireless networks and moving relations from one access point to another access point.
The data frames carry high protocol data in the body of the frame. They are composed of: frame control, the data duration, address and frame body.
In the frame control, they follow certain rules. The bot in this section have an impact on other fields. In duration, the field carries the value of the NAV and follows four vital rules: it has a contention-free duration of 32768, and the frames are sent to a multicast destination that has no duration. The addressing and DS Bits has fields that rely on the distribution system which is set, hence the application of the address fields relies on the form of network allocated.
The control frame helps in the delivery of data frames. They manage access to the wireless channels and offer the MAC-layer reliability duties. It is composed of a common frame control field, request to send, clear to send, acknowledgment and Power-Save Poll.
Lastly there is the management frame which is the biggest component of the standard (Gast, 2002). There are varied forms of management frames that are applied to offer services on a wired network. Acquiring the identity of the network station is made simple since the interface needs the dragging of wires from a point to the new station.
The wireless networks have to form management characteristics so as to offer similar the operability. The standard breaks the process into three forms. The stations looking for connectivity have to acquire compatibility in the wireless network for access. Then the network authenticates the stations to acquire identity for connection. Lastly, the stations have to be associated with the access points so as to acquire the wired core, a process that is similar to plugging the cable into wired network.
Gast Mathew (2002). 802.11 Wireless Networks: The Definitive Guide. San Fransisco: O’Reilly Media, Inc.