General description -2

4.2.4 The impact of handling mobile STAs
One of the requirements of IEEE Std 802.11 is to handle mobile as well as portable STAs. A portable STA
is one that is moved from location to location, but that is only used while at a fixed location. Mobile STAs
actually access the LAN while in motion.
For technical reasons, it is not sufficient to handle only portable STAs. Propagation effects blur the
distinction between portable and mobile STAs; stationary STAs often appear to be mobile due to
propagation effects.
Another aspect of mobile STAs is that they may often be battery powered. Hence power management is
an important consideration. For example, it cannot be presumed that a STA’s receiver is always powered on.
4.2.5 Interaction with other IEEE 802® layers
IEEE Std 802.11 is required to appear to higher layers [logical link control (LLC)] as a wired IEEE 802
LAN. This requires that the IEEE 802.11 network handle STA mobility within the MAC sublayer. To meet
reliability assumptions (that LLC makes about lower layers), it is necessary for IEEE Std 802.11 to
incorporate functionality that is untraditional for MAC sublayers.
In a robust security network association (RSNA), IEEE Std 802.11 provides functions to protect data
frames, IEEE Std 802.1X-2004 provides authentication and a Controlled Port, and IEEE Std 802.11 and
IEEE Std 802.1X-2004 collaborate to provide key management. All STAs in an RSNA have a
corresponding IEEE 802.1X entity that handles these services. This standard defines how an RSNA utilizes
IEEE Std 802.1X-2004 to access these services.
When used to support applications with QoS requirements, each IEEE 802.11 LAN provides a link within an
end-to-end QoS environment that may be established between, and managed by, higher layer entities. To
handle QoS traffic in a manner comparable to other IEEE 802 LANs, the IEEE 802.11 QoS facility requires
the IEEE 802.11 MAC sublayers to incorporate functionality that is not traditional for MAC sublayers. In
addition, it may be necessary for certain higher layer management entities to be “WLAN aware” at least to
the extent of understanding that the available bandwidth and other QoS characteristics of a WLAN are
subject to frequent, and sometimes substantial, dynamic changes due to causes other than traffic load and are
outside the direct control of network management entities.
4.2.6 Interaction with non-IEEE-802 protocols
An RSNA utilizes non-IEEE-802 protocols for its authentication and key management (AKM) services.
Some of these protocols are defined by other standards organizations, such as the Internet Engineering Task
Force (IETF).