The conventional Hotelling’s charts are evidently inefficient as it has resulted in disorganized data with outliers, and therefore, this study proposed the application of a novel alternative robust Hotelling’s charts approach. For the robust scale estimator , this approach encompasses the use of the Hodges-Lehmann vector and the covariance matrix in place of the arithmetic mean vector and the covariance matrix, respectively. The proposed chart was examined performance wise. For the purpose, simulated bivariate bootstrap datasets were used in two conditions, namely independent variables and dependent variables. Then, assessment was made to the modified chart in terms of its robustness. For the purpose, the likelihood of outliers’ detection and false alarms were computed. From the outcomes from the computations made, the proposed charts demonstrated superiority over the conventional ones for all the cases tested.
The wireless mesh network (WMN) has proven to be a great choice for network communication technology. WMNs are composed of access points (APs) that are installed and communicate with each other through multi-hop wireless networks. One or more of these APs acts as a gateway (GW) to the internet. Hosts of WMNs are stationary or mobile. According to the structure of WMNs, some network features may be affected, such as the overall performance, channel interference, and AP connectivity. In this paper, we propose a new adaptive channel allocation algorithm for a multi-radio multi-channel wireless mesh network. The algorithm is aimed to minimize the number of channel reassignments while maximizing the performance under practical constraints. The algorithm defines a decision function for the channel reassignments. The decision function aims to minimize the traffic around the GW. Whenever the traffic changes in the wireless mesh network, the decision function decides which channel radio reassignment should be done. We demonstrated the effectiveness of our algorithm through extensive simulations using Network Simulator 2 (NS-2).
As a scalable, flexible access network to the Internet, we have studied the design optimization and the implementation of the wireless Internet-access mesh network (WIMNET). WIMNET is composed of multiple access points (APs) that are connected with each other by wireless communications. At least one AP performs as the gateway (GW) to the Internet. Any host in the network can access to the Internet through this GW, after associating its neighbor AP and communicating with multihop wireless links between APs. The delay along the routing path degrades the performance of WIMNET. To avoid the bottleneck of communications by minimizing the maximum delay, we formulate the routing tree problem for AP communications, and prove the NP-completeness of its decision version. Then, we propose the greedy heuristic algorithm of sequentially selecting one link that minimizes the delay of the predicted tree containing the link. The effectiveness of our algorithm is verified through extensive simulations in instances with 25 APs using the WIMNET simulator.
1 January 2010 in IEICE Transactions on Communications