How Conservative IEEE 802.11 DCF Is When Using Directional Antenna?

Directional antennas have been introduced to improve the performance of 802.11 based wireless networks. Station equipped with directional antennas can beamform data in a specific direction. However, IEEE 802.11 is developed with omni-directional antennas in mind. Thus, deploying IEEE 802.11 in a directional antenna environment leads stations to be conservative in blocking their own transmissions in favor of the ongoing transmissions. In this paper we study and analyze the limitation of IEEE 802.11 networks with directional antennas. We show analytically that a station with directional antenna and using 802.11 protocol is conservative in terms of assesses channel availability, with as much as 60% of unnecessary blocking assessments. Moreover, by altering the way the 802.11 accessing its MAC data queue, we show that the unnecessary blocking assessments of a node could be increased up to 90%.