Abstract—The use of directional antennas in ad hoc networks has received growing attention because of its high spatial reuse and high antenna gains. The medium access control (MAC) protocol design with directional antennas is nontrivial due to the deafness and collision problems. The existing protocols assumed that the nodes can operate in both directional and omnidirectional modes. However, using both modes leads to the asymmetry-in-gain prob-lem. In this paper, we propose a directional-to-directional (DtD) MAC protocol, where both senders and receivers operate in a directional-only mode. We also derive the saturation throughput of ad hoc networks using DtD MAC. The analytical and simulation results show that DtD MAC can significantly improve the through-put and maintain good fairness among competing flows. We further evaluate the DtD MAC with millimeter-wave (mmWave) communication technologies, which rely on a directional antenna to perform well and can achieve gigabit data rates. The results obtained are exciting and show that DtD MAC is a promising candidate for mmWave ad hoc networks. Index Terms—Ad hoc networks, directional antennas, medium access control (MAC) protocols, millimeter wave (mmWave). I.

Abstract—Directional antennas provide great performance im-provement for wireless networks, such as increased network capacity and reduced energy consumption. Nonetheless new media access and routing protocols are required to control the directional antenna system. One of the most important protocols is neighbor discovery, which is aiming at setting up links between nodes and their neighbors. In the past few years, a number of algorithms have been proposed for neighbor discovery with direc-tional antennas. However, most of them cannot work efficiently when taking into account the collision case that more than one node exist in one directional beam. For practical considerations, we propose a new neighbor discovery algorithm to overcome this shortcoming. Moreover, we present a novel and practical mathematical model to analyze the performance of neighbor discovery algorithms considering collision effects. Numerical results clearly show our new algorithm always requires less time to discover the whole neighbors than previous ones. To the best of our knowledge, it is the first complete, practical analytical model that incorporates directional neighbor discovery algorithms. I.

In this paper we designed a modern Medium access control (MAC) protocol for wireless ad-hoc network that focuses on neighbor node information availability and uses directional antenna. MAC protocol coordinates different users to share the wireless channel fairly and resourcefully in the wireless networks. However, using directional antennas in ad-hoc networks causes new challenges such as new hidden terminal, deafness problems, unnecessary blocking of nodes etc. The problems arise mostly due to lack of information of the neighbor node’s activities. Thus, we proposed a new directional MAC protocol name Adjacent Collaborative Directional MAC Protocol (ACDM) for wireless ad-hoc networks. The objective is to improve the throughput and delay performance together with overhead reduction of the wireless network. In addition, the integrity of the ACDM has been verified using the distributed network simulator tool NS-3. The simulation results have shown that the ACDM protocol outperforms the existing protocols of wireless networks using directional antennas by minimizing the depressing effect of hidden-terminal, deafness and head of line blocking problems that also avoids asymmetry-in-gain problem. The performance of ACDM protocol shows that it improves the throughput and reduces the overhead from the state-of-art works.