The value of position field will be used later in DSIA routing metric, but how to use it depends on traffic pattern and we will show it below.
We define traffic-related factor as [[delta].sub.l], which exhibits the service differentiated characteristics of DSIA routing metric.
So DSIA metric for path p can be expressed as follows:
DSIA (p) = [n.summation over (link l [member of] o)] CC_[PBLoadi.sub.I] + [gamma] x [m.summation over (node i [member of] p)] [CSC.sub.i] + [theta] x (1 - [Capr.sub.g]), (13)
DSIA is an isotonic metric which takes traffic pattern, node load, gateway load, and interference into consideration and it can detect heavy load and heavy interference areas in the network and guide packets to bypass these areas.
In order to evaluate the decisions made by proposed DSIA routing metric, we designed extensive simulations to compare it with other metrics.
Superiority of DSIA. In order to demonstrate the effectiveness of our DSIA routing metric in distinguishing service and selecting gateway, respectively, the experiments are conducted in two scenarios.
In single-gateway WMNs, our DSIA is compared with MIC and INX based on the metrics listed in Section 4.1.
Our DSIA routing metric outperforms MIC and INX, as it comprehensively takes traffic pattern, node load, and intraflow and interflow interference into consideration and provides powerful assistance for routing selection.
As shown in Figure 4, DSIA has the lowest packet loss rate among the three metrics, which is due to the comprehensive consideration of factors affecting packet loss, so that packets will be guided to route through paths with low loss rate.
In multigateway WMNs, our DSIA is compared with the nearest gateway selection algorithm, load-based gateway selection algorithm, and BP2BG based on the metrics listed in Section 4.1.