en 5-Wireless Access (WLL, WLAN, WPAN) Wireless Access (WLL, WLAN, WPAN) Research Paper Research Paper The use of directional antennas in wireless ad hoc networks can significantly improve global performance due to a high spatial channel reuse. Nevertheless, its introduction poses new location dependent problems related to the MAC protocol. In this paper, the Balanced Incomplete Block Design theory has been exploited to develop a new MAC protocol for wireless ad hoc networks using directional antennas. It is a time slotted protocol, which is highly scalable. Moreover, it can provide a high number of concurrent communications, depending on the number of directional antennas mounted on each node, great fairness in bandwidth sharing and significant energy saving. In particular, energy saving provided by our scheme is consistently higher compared to those of usual directional MAC protocols for the following reasons. Firstly, control packets are sent only over fairly selected beams rather than over all the available ones. Secondly, our protocol provides a filtering, i.e. a fair selection, of the nodes that can try the access to the medium in each time slot. Simulation results validate the advantages of our protocol by proving high spatial reuse, great fairness and significant energy saving and by showing that it improves the overall system performance. Directional Antennas,Medium Access Control,Spatial Reuse,Wireless Ad Hoc Networks, 93 101 http://ijeee.iust.ac.ir/browse.php?a_code=A-10-3-83&slc_lang=en&sid=1 Gennaro Boggia 18003194753284600413 18003194753284600413 Yes Pietro Camarda 18003194753284600414 18003194753284600414 No Claudia Cormio 18003194753284600415 18003194753284600415 No Luigi Alfredo Grieco 18003194753284600416 18003194753284600416 No