  IEEE 802.11ad specifies a hybrid medium access control (MAC) protocol
consisting of contention as well as noncontention-based channel access
mechanisms. Further, it also employs directional antennas to compensate for the
high freespace path loss observed in 60GHz frequency band. Therefore, it
significantly differs from other IEEE 802.11(b/g/n/ac) MAC protocols and thus
requires new methods to analyze its performance. In this paper, we propose a
new analytical model for performance analysis of IEEE 802.11ad employing a
threedimensional Markov chain considering all the features of IEEE 802.11ad
medium access mechanisms including the presence of non-contention access and
the different number of sectors due to the use of directional antennas. We show
that the number of sectors has a high impact on the network throughput. We also
show that the MAC packet delay is significantly affected by the duration of the
contention period. Our results indicate that a suitable choice of the number of
sectors and contention period can illustriously improve the channel utilization
and MAC delay performance.
