| | 1 | [[TracNav(802.11/TOC)]] |
| | 2 | |
| | 3 | = 802.11 Reference Design: Frame Retries = |
| | 4 | |
| | 5 | An important role of the 802.11 DCF is to detect the presence of transmission failures and properly recover from those errors through the use of a retransmission mechanism. This behavior is subtle and often misunderstood. This document serves two roles: |
| | 6 | |
| | 7 | 1. To describe the behavior implemented in the Mango 802.11 Reference Design. |
| | 8 | 1. To defend the behavior with references to the 802.11 standard. |
| | 9 | |
| | 10 | The organization of this document is a series of examples that build on one another and show corner cases in the behavior. The retransmission mechanism in 802.11 is further complicated by the presence of RTS/CTS medium reservation handshakes prior to the transmission of an MPDU, so examples are broken up into sections depending on whether RTS/CTS is not used (i.e. an MPDU is "short") or RTS/CTS is used (i.e. an MPDU is "long"). Without loss of generality, the examples in this document assume the following parameters: |
| | 11 | |
| | 12 | * ''dot11ShortRetryLimit'' = 7 |
| | 13 | * ''dot11LongRetryLimit'' = 4 |
| | 14 | |
| | 15 | === Glossary of Terms === |
| | 16 | |
| | 17 | ||= '''Term''' =||= '''Definition''' =|| |
| | 18 | || '''SRC''' || Short Retry Count || |
| | 19 | || '''LRC''' || Long Retry Count || |
| | 20 | || '''SSRC''' || Station Short Retry Count || |
| | 21 | || '''SLRC''' || Station Long Retry Count || |
| | 22 | || '''CW''' || Contention Window || |
| | 23 | |
| | 24 | = Short MPDUs (MPDU length ≤ ''dot11RTSThreshold'') = |
