How Does a Wireless LAN Work

If you want to connect a few laptops within a limited range, to form a network, then wireless LAN is perhaps the best solution. Most laptops that are manufactured today, come along with the wireless network feature. It thus becomes a very simple task to connect all the laptops in a local area network. You have to simply follow the steps in the wireless network connection wizard to form a network of your own and allow other laptop users to join your network. Similarly, you can connect more than one desktop computers to form a wireless LAN, but in this case you will need a wireless setup or a wireless router. Now, the question is, how does a wireless LAN work, when there is no medium for the transfer of information. Let us try to answer this question from the technical perspective.

Wireless LAN Protocol
A protocol is a set of rules that decides the performance or execution of a certain task. In communication it is the set of rules that decides the way information will be transferred and received. It also decides the speed and bandwidth that can be allowed for the flow of information. For a wired LAN structure, the Ethernet LAN standard was used. However, this structure was not sufficient for the wireless LAN, as there was no fixed medium for the transfer of information. Additional information was needed for transmitting the packets or frames of data. For wireless LAN, IEEE 802.11g standards are used. Previously, IEEE 802.11b standards were used. 802.11g standard can work with a speed upto 56Mbps, where as 802.11b could work at speeds of 10-12Mbps. This standard also allows the working at a frequency of 2.4GHz.

Frame Structure
802.11 standard defines the two basic layers for the transmission and reception of data; the physical layer and the MAC (Media Access Control) layer. The data in wireless LAN is sent in the form of frames, just as in the case of any other network. The frame structure in wireless network can be described as under:

Frame Control Field: It is a 2 bytes long field. A lot of information is confined in this field and it has 11 sub-fields. Information like, what is the version of the protocol, power management and whether the information being transmitted is data or command, is mentioned in this field. There are various other factors too, that are mentioned in this field.

Address Field: Here the destination address is defined. Unlike other network protocols, the 802.11 structure allows four address fields. One of the fields, holds the MAC address of the final recipient and another holds the MAC address of the source recipient. The remaining two fields are used to hold the MAC address of the immediate recipient and the transmitting station.

Frame Body: This is the field that contains the data that is to be transmitted.

Frame Check Sequence(FCS): This is the last field of the frame. It is 4 bytes long and allows the receiver to perform error control operations.

The data is thus sent by one device to another in the format described above. All these information in a frame help it in successfully identifying the destination machine. The destination machine does the required checks before acknowledging the frame. It also performs the required checks like whether the received information is data or a command. This type of information, as mentioned above in the frame structure, is contained in the Frame Control Field.

Other Features
The 802.11 structure allows the different client machines connected in a LAN to communicate at multiple data rates. The data rate is selected depending upon the highest possible speed at which there will be minimum number of errors.

Here, in this article, I have tried to answer the question how does a wireless LAN work, with a technical perspective. There are various features of wireless LAN that make it an easy to implement setup. For laptops, it does not require any external accessory. If you want to connect a wireless LAN network to a wired LAN, you just need to simply bridge the connection and your network gets enlarged.