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5. Another scheme is multihop RTS MAC (M-MAC) for
transmission on multihop paths. As directional antennas
have a higher gain and transmission range than omnidirec-
tional antennas, a node that is far away from another node
communicates directly. For communicating with distant
nodes, M-MAC uses multiple hops to send RTS packets to
establish a link, but the subsequent CTS, data, and ACK
packets are sent in a single hop. is protocol can achieve
better throughput and end-to-end delay than the basic
IEEE 802.11 and the D-MAC schemes. Depending on
the topology configuration and flow patterns of the system,
the performance also varies. Directional antennas bring in
three new problems: (1) new kinds of hidden ter