An overview of IEEE 802.11 (wireless network standard) Essay

An overview of IEEE 802.11 (wireless network standard) - Essay Example It is the most widely used wireless network standard. 802.11b standard was ratified by IEEE in 1999. The main features of this standard are as given below.These features are adequate for most data transfer applications and for accessing internet but might be inadequate for multimedia acce It might also face problems when users in large number access the network from a single access point. The frequency of operation, i.e., 2.4 GHz, coincides with the spectrum used by cordless phones, microwave ovens, etc. Therefore the interference problems are more likely to occur.802.11a suits to the conditions of multiple users accessing the network with high data rates. It is best suited for classrooms where students can access multimedia, digital video or database packages (BECTA, 2005).IEEE accepts the 802 standard logical link control (LLC) protocol. It also offers, for the purpose of wireless communication, physical layer (PHY) and medium access control (MAC) sub layers. There are two physical layers offered by 802.11 namely, direct sequence spread spectrum (DSSS) and frequency hopping spread spectrum (FHSS). According to the transmission methods and frequencies 802.11 is categorised into three main groups; 802.11b, 802.11a, 802.11g. The main features of these three categories have already been stated above. The main drawback of 802.11a is that it is not backward compatible with 802.11b as both of them use a different frequency spectrum. This results in lesser interest of users towards 802.11a. The advantage of 802.11a, however, is that it operates in 5 GHz spectrum which can be used unlicensed. The 2.4 GHz spectrum used by other two standards interferes with that of other devices such as cordless phones and microwave ovens. The 802.11 MAC supports two basic medium access protocols: contention-based distributed coordination function (DCF) and optional point coordination function (PCF). (Zhu, Hua, Li, Ming, Chlamtac, Imrich & Prabhakaran, B., 2004). PCF causes the wireles s channel to be divided into super frames. Super frames in turn provides two periods, a contention-free period (CFP) for PCF and a contention period (CP) for DCF. There is a device known as point co-ordinator which is usually an access point (AP). The point co-ordinator polls for grant of access to the wireless channel at the start of CFP. On obtaining the channel, it checks the stations regularly and sets priorities to these stations as per their importance, i.e., their