  Recent advances in antenna technology have made the design of multi-beam
antennas (MBA) feasible. Compared to an omni-directional or a single beam
directional antenna, an MBA equipped node can achieve a throughput of up to m
times, by simultaneously communicating on its m non-interfering beams. As a
result, a few multi-beam directional medium access control (MAC) schemes have
been proposed in the literature recently, which are implemented mostly on the
in-house simulation setups in Matlab or C/C++. These implementations make many
assumptions to simplify their design, without a thorough implementation of
other network layers. However, the implementation of a multi-beam MAC scheme on
the well-known discrete event network simulator platforms (such as the Riverbed
Modeler, NS3, QualNet) is challenging as it requires extensive changes and
additions to various source code modules. In fact, the network protocols in
these simulator packages have been mainly designed for omni-directional
communication, and very few implementations of directional MAC and other
network protocols exist in the literature.
  This paper presents a framework to implement a multi-beam directional MAC
scheme in multi-hop wireless networks, by using the Wireless Suite of Riverbed
Modeler. The detailed implementation procedures are described for multi-beam
antenna module, multi-beam node model, concurrent packet transmission and
reception, scheduling, collision avoidance, retransmission, and local node
synchronization. These MAC modules and methodology can be very helpful to the
researchers and developers for implementing the single-beam as well as
multi-beam directional MAC and routing protocols in Riverbed Modeler.
