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Figure 14. Throughput Comparison according to the number of used channels
period inefficiencies as in LCM-MAC or MMAC.
Also, note that H-MAC, in fact, provides k time
the throughput relative to 802.11 while using k
channel. This is because of using the hybrid scheme
by H-MAC. LCM MAC also provides substantial
improvement over 802.11, slightly less than k
times for the 3 and 6 channel simulations. But,
the throughput does not increase proportionately
for 13 channels.
among all MAC protocols which use hybrid
scheme and channel diversity with a single radio.
H-MAC performs better than Z-MAC although
their channel utilization rate is almost the same.
In addition, the simulation results on channel
diversity show that H-MAC provides a far supe-
rior performance compared to both LCM-MAC
and MMAC.
Some of the issues not discussed in this article
are the non-negligible channel switching delay and
different data packet sizes as well as mechanisms
for broadcasts in our protocols. Thus, we have
not performed the simulation tests which allow
to evaluate the QoS support and its impact on
data throughput measurement. This is because
of non availability of MAC protocols with QoS
implementations during our simulation. In future
work, we intend to study the above issues. We will
implement and test the studied protocols in real
wireless testbeds using different software-based
MAC platforms.
CONCLUSION
This article presents a new multi-channel MAC
protocol, called H-MAC for the multi-hop wire-
less mesh networks. H-MAC can dynamically
adjust the behavior of MAC between CSMA and
TDMA depending on the level of contention in
the network.
The observed simulation results show that our
protocol provides much superior performance
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