Wireless Internet-access Mesh Network Research Articles

Cross-layer selective routing for cost and delay minimization in IEEE 802.11ac wireless mesh network

A Wireless Internet-access Mesh NETwork (WIMNET) provides scalable and reliable internet access through the deployment of multiple access points (APs) and gateways (GWs). In this work, we propose a selective routing algorithm aiming at a hierarchical minimization of the operational cost and the maximal end-to-end delay. In particular, by deploying redundant APs/GWs in the network field, the WIMNET becomes robust to the link or AP/GW failure. However, these redundant APs/GWs increase the operational cost like the power consumption. By using Dijkstra algorithm and 2-opt algorithm, the proposed algorithm iteratively deactivates the deployed APs/GWs and performs the routing that reduces the maximal end-to-end delay based on the APs/GWs remaining active. The generated route meets the real-world constraints like fairness criterion. We further propose a cross-layer design to enhance the routing performance by exploiting the MAC-layer frame aggregation technique. The selective routing algorithm is then implemented in the WIMNET simulator proposed by our group. The numerical experiments demonstrate that in both indoor and open space environments, the proposed selective routing greatly reduces the operational cost, i.e., up to \(80\%\) APs/GWs can be deactivated.

An extended active access-point selection algorithm for link speed changes in wireless mesh networks

As an inexpensive, scalable internet-access network, a wireless internet-access mesh network ( WIMNET ) is composed of multiple access-points ( APs ) connected by wireless links. WIMNET can improve the dependability to link or AP failures by allocating APs redundantly in the network field. Because redundant APs may increase the operational cost and degrade the performance due to increasing radio interferences, only the necessary APs for communications between the hosts and the internet gateway should be activated in conventional situations. Previously, we proposed an active AP selection algorithm to select the minimum number of APs to be activated such that the overall throughput is maximised, assuming that every link has the same constant speed. However, our preliminary experiments for the emerging high-speed IEEE802.11n protocol that should be introduced into WIMNET, found that this speed is greatly affected by the link environment such as the distance. In this paper, we present an extension of the active AP selection algorithm to efficiently select active APs under link speed changes. Besides, we extend the routing tree algorithm used in the algorithm procedure and the WIMNET simulator for throughput evaluations. We verify the effectiveness through extensive simulations in three instances.

A Fixed Backoff-Time Switching Method for CSMA/CA Protocol in Wireless Mesh Networks

SUMMARY As a flexible and cost-efficient scalable Internet access network, we studied architectures, protocols, and design optimizations of the Wireless Internet-access Mesh NETwork (WIMNET) .W IMNET is composed of multiple access points (APs) connected through multihop wireless communications on IEEE 802.11 standards. The increasing popularity of real-time applications such as IP-phones and IP-TV means that they should be supported in WIMNET. However, the contention resolution mechanism using a random backoff-time in the CSMA/CA protocol of 802.11 standards is not sufficient for handling real-time traffic in multihop wireless communications. In this paper, we propose a Fixed Backoff-time Switching (FBS) method for the CSMA/CA protocol to improve the real-time traffi cp erformance in WIMNET by giving the necessary activation chances to each link. We implement our proposal on the QualNet simulator, and verify its effectiveness through simulations on three network topologies with four scenarios.

AN ACTIVE ACCESS-POINT SELECTION APPROACH FOR DEPENDABLE WIRELESS MESH NETWORKS

As an inexpensive, flexible, and scalable Internet-access wireless network, we have studied the architecture, protocols, and design optimizations of the Wireless Internet-access Mesh NETwork (WIMNET) that adopts multiple access-points (APs) connected through wireless links. WIMNET can improve the dependability to failures of APs and/or their links by allocating APs redundantly in the network field. Because redundant APs may increase the operational cost and degrade the throughput due to increasing radio interferences, only the necessary APs for connectivity between the hosts and the Internet gateway should be activated in communications. In this paper, we first define the active AP selection problem of selecting the minimum number of active APs, and prove the NP-completeness of its decision version through reduction from the known minimum set cover problem. Then, we propose an active AP selection algorithm of deactivating APs one by one until no more AP can be deactivated. Due to the limited transmission capacity in WIMNET, we further present an algorithm extension for throughput maximization. We verify the effectiveness of our proposal through simulations in three instances, where the number of active APs is reduced by more than 40% and the throughput is improved by more than 10% from the original in any instance.

Extensions of the Access Point Allocation Algorithm for Wireless Mesh Networks

Previously, we have proposed an access point (AP) allocation algorithm in indoor environments for the Wireless Internet-access Mesh NETwork (WIMNET) using one gateway (GW) to the Internet. WIMNET consists of multiple APs that are connected wirelessly mainly by the Wireless Distribution System (WDS), to expand the coverage area inexpensively and flexibly. In this paper, we present two extensions of this algorithm to enhance the applicability to the large-scale WIMNET. One is the multiple GW extension of the algorithm to increase the communication bandwidth with multiple GWs, where all the rooms in the network field are first partitioned into a set of disjoint GW clusters and then, our previous allocation algorithm is applied to each GW cluster sequentially. The APs in a GW cluster share the same GW. The other is the dependability extension to assure the network function by maintaining the connectivity and the host coverage, even if one link/AP fault occurs, where redundant APs are added to the AP allocation by our previous algorithm. The effectiveness of our proposal in terms of the number of APs and the throughput is verified through simulations using the WIMNET simulator.

An Access Point Allocation Algorithm for Indoor Environments in Wireless Mesh Networks

As a flexible, cost effective solution for a large-scale access network to the Internet, we have studied the design optimization of the Wireless Internet-access Mesh NETwork (WIMNET). WIMNET consists of multiple access points (APs) that have wireless links between them mainly on the wireless distribution system (WDS). In WIMNET, the links around the Internet gateway can be bottlenecks because every packet passes through it after multihop link activations. Besides, the link quality may be degraded by obstacles in indoor environments. Thus, the proper allocation of APs is essential in WIMNET, so that the communication quality should be ensured while the installation and management cost be minimized. In this paper, we formulate this AP allocation problem for indoor environments in WIMNET with the proof of the NP-completeness of its decision version. Then, we present its two-stage heuristic algorithm composed of the initial greedy allocation and the iterative improvement. The effectiveness of our proposal is verified through extensive simulations in three indoor environments.