5%
and 31.3% respectively due to the increased probability of collision. The fundamental
conclusion is that by using AIFSN=3, an EDCA station can be set to operate like a legacy
17 Quantification is easy: after a successful transmission, a DCF station transmits in the slot 0 only if it extracts a
backoff counter equal to 0. This occurs with probability 1/(1+CWmin) 3.1%. This conditional probability is
consistent with the absolute probability value reported in Figure 4.17 (about a half of this), since about half of the
busy periods are successful DCF transmissions.
?‰?
Performance Study of IEEE 802.11 DCF and IEEE 802.11e EDCA 99
DCF station. With reference to the proposed EDCA parameter settings reported in Table
4.3, we thus conclude that an EDCA station belonging to the Access Category AC_BE will
experience similar performance than a legacy DCF station. The above quantitative analysis
also justifies why DCF shows a slightly superior throughput performance over EDCA
AC_BE, as depicted in Figure 4.15 under the case of AIFSN=3.
4.5.3.3 AIFSN=2 and Legacy DCF Stations
As shown in Table 4.3, AIFSN=2 is the minimal setting allowed for an EDCA station.
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