The initial ieee 802.11 PAR (project authorization request) states, “…the scope of the proposed [wireless LAN] standard is to develop a specification for wireless connectivity for fixed, portable, and moving stations within a local area.” The PAR further says, “…the purpose of the standard is to provide wireless connectivity to automatic machinery and equipment or stations that require rapid deployment, which may be portable, handheld, or which may be mounted on moving vehicles within a local area.”
The resulting standard, which is officially called “IEEE Standard for Wireless LAN Medium Access (MAC) and Physical Layer (PHY) Specifications,” defines over-the-air protocols necessary to support networking in local areas. As with other IEEE 802-based standards (e.g. 802.3, and 802.5), the primary service of the 802.11 standard is to deliver MAC service data units (MSDUs) between peer logical link controls (LLCs). Typically, a radio card and AP provide functions of the 802.11 standard
IEEE 802.11 Features :
The 802.11 standard provides MAC and PHY functionality for wireless
connectivity of fixed, portable and moving stations moving at pedestrian and vehicular speeds within a local area . The 802.11 standard takes into account the following significant differences between wired and WLANs:
Power management: Most WLAN network interface cards (NICs) are available in PCMCIA format; thus one can outfit portable and mobile handheld computing equipment with WLAN connectivity. The problem, though, is that these devices must often rely on batteries to power the electronics within them. The addition of a WLAN NIC to a portable computer can quickly drain batteries. The 802.11 working group (WG) struggled with finding solutions to conserve battery power; however, they found techniques enabling wireless NICs to switch to lower-power standby modes periodically when not transmitting, reducing the drain on the battery. The MAC layer implements power management functions by putting the radio to sleep (i.e., lowering the power drain) when no transmission activity occurs for some specific or user-definable time period. The problem, though, is that a sleeping station can miss critical data transmissions. 802.11 solves this problem by incorporating buffers to queue messages. The standard calls for sleeping stations to awaken periodically and retrieve any applicable messages.
Bandwidth: The industry, scientific, and medical (ISM) spread spectrum (SS) bands do not offer a great deal of bandwidth, keeping data rates lower than desired for some applications. The 802.11 WG, however, dealt with methods to compress data, making the best use of available bandwidth.
Security: WLAN signals can be received within a certain area and do no need a galvanic connection with wired media, such as twisted-pair, coaxial cable, and optical fiber. In terms of privacy, therefore, wireless LANs have a much larger area to protect. To employ security, the 802.11 group coordinated its work with the IEEE 802.10 standards committee responsible for developing security mechanisms for all 802 series LANs. This IEEE 802.11 security solution is enhanced by IEEE 802.11.
Addressing: The topology of a wireless network is dynamic; therefore, the destination address does not always correspond to the destination’s location. This raises a problem when routing packets through the network to the intended destination. The 802.11f recommendation on inter access point protocol (IAPP) solves this issue.