However, standard SCTP uses only a pair of primary IP addresses at a time which does not allow concurrent transmissions. CMT is a modified version of SCTP that allows concurrent transmissions and includes selleck kinase inhibitor few improvements on fast retransmission, congestion window update, and delayed acknowledgment algorithms. It was found in  that the receiving buffer, referred to as rBuf in the original paper, can be a performance bottleneck of CMT. Therefore, we only compare the best CMT results without such constraint, called CMT Unlimited, as a reference in this section. We did not implement our proposal over TCP or SCTP because in the TCP scheme, due to various control mechanisms, for example, rate control and congestion avoidance control, end-to-end delays do not generally follow a Gaussian distribution.
There are a few special cases when TCP traffic does follow a Gaussian distribution [20, 21]; however, we leave the investigation of those cases as a future work. Currently, to study the pure behavior of our proposal, we assume that the end-to-end information is known to the source node without an actual measurement. However, a feedback mechanism can be easily implemented to deliver this information to the source node. Since the statistical information is needed only once every execution interval, the overhead can be considered negligible and the actual results should be similar to the simulation results shown in this paper. Moreover, to have a fair comparison, our comparison targeting MPRTP also uses the same assumptions.4.2.
Static ScenarioWe set up the simulation scenario exactly the same as described in ; see Figure 3. There are two chains of nodes where the distance between nodes on the same chain is 300m and the distance between chains is 450m. The transmission range of each node is approximately 370m where the carrier sensing range and the interference range span farther under the two-ray path loss model without fading. The default transmission range in QualNet 5.2 is only 300m and we matched the transmission range to  by slightly increasing the TX power.Figure 3Simulation scenario from .In this scenario, one chain serves as the main concurrent multipath sessions for bandwidth evaluation and the other chain serves as interfering background traffic. On the main chain, each node is equipped with two IEEE 802.
11b interfaces connected to two noninterfering channels. On the background traffic chain, each node is equipped with only one interface connected to the second channel which is used in the main chain. The data rate for IEEE 802.11b is 2Mbps and the RTS/CTS mechanism is enabled. Static routes are used in this simulation to eliminate complications due to the effect of the routing protocol.The number of nodes varies from 10 to 34 (4, 8, and Cilengitide 16 hops on each chain). The traffic used in this evaluation is CBR with 1000 bytes per packet.