1. CognitiveRadio-Aware TransportProtocolfor Mobile Ad Hoc Networks
Abstract:
With the proliferation of new wireless service, scarce wireless resources is
expected to become a critical issue. For this reason, cognitive radio mobile
ad hoc networks (CogMANET) are being developed as a promising
solution to this problem. However, in CogMANET, channel switching is
inherently necessary whenever a primary user with a license appears on
the channel. Allowing secondary users to choose an available channel from
among a wide spectrum range thus enables reliable communication in this
context, but communication characteristics such as bottleneck bandwidth
and RTT will change with channel switch. In response to this change, TCP
has to adaptively update its congestion window (cwnd) to make an
efficient use of the available resources. For this purpose, TCP CRAHN was
proposed for CogMANET. In this paper, TCP CRAHN is first evaluated in
cases where bottleneck bandwidth and RTT drastically change. Based on
these results, TCP CoBA is proposed to further improve the throughput of
the above use cases. TCP CoBA updates the cwnd based upon the available
buffer space in the relay node upon channel switch, as well as other

2. communication characteristics. Through simulations, we show that
compared with TCP CRAHN, TCP CoBA improves the throughput by up
to 200 percent.