Figure 9-15. Transaction Between Stations A And B - Alvarion BreezeNET PRO.11 Series User Manual

Appendix
The NAV State is combined with the physical carrier sense to indicate the busy
state of the medium.
9.5.3.3 MAC Level Acknowledgments
As mentioned earlier in this document, the MAC layer performs Collision
Detection by expecting the reception of an acknowledge to any transmitted
fragment (Packets that have more than one destination, such as Multicasts, are not
acknowledged.)
9.5.3.4 Fragmentation and Reassembly
Typical LAN protocols use packets several hundred bytes long (the longest
Ethernet packet could be up to 1518 bytes long).
There are several reasons why it is preferable to use smaller packets in a wireless
LAN environment:
Due to the higher Bit Error Rate of a radio link, the probability of a packet
getting corrupted increases with the packet size.
In case of packet corruption (either due to collision or noise), the smaller the
packet, the less overhead it causes to retransmit it.
On a Frequency Hopping system, the medium is interrupted periodically for
hopping (in our case every 20 milliseconds), so, the smaller the packet, the
smaller the chance that the transmission will be postponed after dwell time.
User's Guide

Figure 9-15. Transaction Between Stations A and B

9-30 BreezeNET PRO.11 Series