Cerio OW-200N2 User Manual page 93

set to 3, then the Wi-Fi clients will expect to receive a multicast frame after receiving
three Beacon frame. The higher DTIM interval will help power saving and possibly
decrease wireless throughput in multicast applications.
3.5.3 Fragment Threshold : The Fragment Threshold is in the range of 256~2346 byte.
The default is 2346 byte.
Each Wi-Fi packet can be divided into smaller packets, marked with a sequential
fragment number and re-assemble in the receiving ends. The purpose is to make a
short frame, instead of long frame, transmitting by radio in a heavy noisy environment.
Because of sending smaller frames, corruptions are much less likely to occur. The
pros is obvious, the cons is the overhead for transmission. So, in a clean environment,
higher fragment threshold can be an option to increase throughput.
Fragmentation will be triggered by setting the Fragment Threshold, usually in
Byte-length. Only when the frame size is over the Threshold, fragmentation will take
place automatically.
3.5.4 RTS Threshold : TRTS Threshold is in the range of 1~2347 byte. The default is 2347
byte.
The main purpose of enabling RTS by changing RTS threshold is to reduce possible
collisions due to hidden wireless clients. RTS in AP will be enabled automatically if
the packet size is larger than the Threshold value. By default, RTS is disabled in a
normal environment supports non-jumbo frames.
3.5.5 Short Preamble : By default, it's "Enable". To Disable is to use Long 128-bit
Preamble Synchronization field.
The preamble is used to signal "here is a train of data coming" to the receiver. The
short preamble provides 72-bit Synchronization field to improve WLAN transmission
efficiency with less overhead.
3.5.6 Short Slot : By default, it's "Enable" for educing the slot time from the standard 20
microseconds to the 9 microsecond short slot time
Slot time is the amount of time a device waits after a collision before retransmitting a
packet. Reducing the slot time decreases the overall back-off, which increases
throughput. Back-off, which is a multiple of the slot time, is the random length of time
a station waits before sending a packet on the LAN. For a sender and receiver own
right of the channel the shorter slot time help manage shorter wait time to re-transmit
from collision because of hidden wireless clients or other causes. When collision
500mW eXtreme Power 11Na Outdoor Bridge
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User's Manual