This paper presented a performance and fairness evaluation
study, in wireless mesh networks, of the most popular
congestion control protocol, TCP, against new congestion
control techniques, namely XCP and RCP, that use network
interaction for rate adaptation. Different strategies were used
for the evaluation. Initially, a static network was used, and then
different mesh topologies with both fixed and mobile nodes
were tested.
Our results show that TCP is more efficient than XCP and RCP
in mesh scenarios. TCP is more fair and stable than XCP and
RCP. This is due to the AIMD strategy of TCP. XCP is the less
efficient protocol, as it increases delay in the communications.
To obtain the available network capacity, both XCP and RCP
need that all nodes in the network cooperate, which increases
network overhead, specially when dealing with wireless mesh
networks. Moreover, TCP, RCP and XCP are not taking
into consideration losses due to interference or weak signal
strength; this is more relevant in XCP and RCP as they need
to evaluate the available capacity. Finally, the nodes in XCP
and RCP are not evaluating precisely network capacity, thus
leading to a poor network performance.
We believe that new techniques for congestion control can be
developed and can increase congestion control performance.
We are currently studying and applying new congestion control
techniques to these control protocols, making use of
cross-layer information and techniques to provide accurate
mechanisms to evaluate the available bandwidth in dynamic
networks, as it is the case of WMNs.