PLANET WNAP-7205 - Manual (Page 89)

User’s Manual of WNAP-7205
29. What is WLAN Block Relay between Clients?
An Infrastructure Basic Service Set is a BSS with a component called an Access Point (AP). The
access point provides a local relay function for the BSS. All stations in the BSS communicate with the
access point and no longer communicate directly. All frames are relayed between stations by the
access point. This local relay function effectively doubles the range of the IBSS.
30. What is WMM?
WMM is based on a subset of the IEEE 802.11e WLAN QoS draft standard. WMM adds prioritized
capabilities to Wi-Fi networks and optimizes their performance when multiple concurring applications,
each with different latency and throughput requirements, compete for network resources. By using
WMM, end-user satisfaction is maintained in a wider variety of environments and traffic conditions.
WMM makes it possible for home network users and enterprise network managers to decide which
data streams are most important and assign them a higher traffic priority.
31. What is WLAN ACK TIMEOUT?
ACK frame has to receive ACK timeout frame. If remote does not receive in specified period, it will be
retransmitted.
32. What is Modulation Coding Scheme (MCS)?
MCS is Wireless link data rate for 802.11n. The throughput/range performance of an AP will depend on
its implementation of coding schemes. MCS includes variables such as the number of spatial streams,
modulation, and the data rate on each stream. Radios establishing and maintaining a link must
automatically negotiate the optimum MCS based on channel conditions and then continuously adjust
the selection of MCS as conditions change due to interference, motion, fading, and other events.
33. What is Frame Aggregation?
Every 802.11 packet, no matter how small, has a fixed amount of overhead associated with it. Frame
Aggregation combines multiple smaller packets together to form one larger packet. The larger packet
can be sent without the overhead of the individual packets. This technique helps improve the efficiency
of the 802.11n radio allowing more end user data to be sent in a given time.
34. What is Guard Intervals (GI)?
A GI is a period of time between symbol transmission that allows reflections (from multipath) from the
previous data transmission to settle before transmitting a new symbol. The 802.11n specifies two
guard intervals: 400ns (short) and 800ns (long). Support of the 400ns GI is optional for transmit and
receive. The purpose of a guard interval is to introduce immunity to propagation delays, echoes, and
reflections to which digital data is normally very sensitive.
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