Rosewill RNX-N400LX - Manual (Page 68)

Wireless Router RNX-N400LX User Manual
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 transmissions that allows reflections (from
multipath) from the previous data transmission to settle before transmitting a new symbol.
The 802.11n draft 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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