Large-scale Wireless Local Area Networks Research Articles

Multiobjective planning of indoor Wireless Local Area Networks using subpermutation-based hybrid algorithms

Wireless Local Area Network (WLAN) has become the most popular technology for mobile Internet access in recent decades. This manuscript presents a novel approach, based on hybrid optimization algorithms, for planning WLANs. Two objective functions are optimized: to maximize network load balance and signal-to-noise ratio. In addition, constraints related to coverage, customer, and equipment demand are considered. A key aspect of the proposed algorithm is its new representation/decoding scheme, based on subpermutations, which considerably reduces the search space dimension. This structure guarantees feasibility of the obtained solutions and increases the computational efficiency of the method. Several tests were performed in two scenarios, one of them using real data from a large-scale WLAN. When compared to other three approaches, such results show that the proposed method provides solutions that reduce costs and improve the WLAN throughput.

User Behavior and Devices Analysis of a Large-scale Wireless Local Area Network Based on DHCP

The Dynamic Host Configuration Protocol (DHCP) is used to effectively allocate IP addresses on a local area network. Despite the widespread usage of DHCP, few studies related to users exist on DHCP server logs, and even less is known about the user behavior and devices of a large-scale wireless local area network (WLAN). In this paper, we propose a methodology to feasibly analyse mobility and concentration of users and generally analyse the temporal distribution and the providers’ distribution of wireless devices. The method is not involved with user privacy and safety, and fully explores available DHCP metrics and logs. Our results show that individual users are more likely to concentrate in labs and classrooms on weekdays while they prefer to concentrate in their dormitory and library on the weekends. The online time of 80% of wireless devices is less than 10 hours and the provider Apple takes nearly 50% of all wireless devices according to the data set of T University. We except similar benefits to arise for analyzing large-scale WLAN and optimize DHCP.

Link-Layer Multicast in Large-Scale 802.11n Wireless LANs with Smart Antennas

In wireless local area networks (WLANs), link-layer multicast is a promising technology for many multimedia applications, e.g., video streaming, as multicast frames can reach multiple clients simultaneously. However, the efficiency of multicast in WLANs is usually low since multicast frames are transmitted at a basic data rate to reach clients with poor channel quality. Moreover, the reliability of multicast cannot be guaranteed either, as multicast transmissions are not acknowledged. Some recent works have utilized smart antennas to improve multicast performance. However, most of them require customized hardware and are not designed for the latest IEEE 802.11 standard, 802.11n WLANs. More importantly, these works did not consider the impact of AP association strategies on the performance of link-layer multicast. In this paper, we study the problem of link-layer multicast in large-scale 802.11n WLANs where each AP is equipped with a smart antenna that supports multiple antenna patterns. Based on channel gains of various antenna patterns from different APs, we choose the associated AP for multicast clients, partition associated clients of each AP into multiple groups, select an antenna pattern and data rate for each group of client, and transmit multicast frames to each group once. We first examine the limitation of multicast in 802.11n WLANs and the benefits of smart antennas to multicast via experiments. We then introduce the system model and formulate the problem into an optimization problem, and prove its NP-hardness. The objective is to minimize the time to transmit a multicast frame to all clients while guaranteeing high packet reception ratio (PRR) for each client. For generic WLANs where APs are sparsely deployed, we propose an optimal algorithm under the condition that the PRR of antenna patterns and data rates are known for every client. For generic large-scale WLANs, we further propose an on-line algorithm in which the AP association strategy, the partition of clients, the antenna pattern and data rate of each group are adapted dynamically, based on PRR reports from clients. We have implemented the on-line algorithm on off-the-shelf WLAN products, and conducted extensive experiments and simulations to evaluate the performance. The results show that the proposed algorithm can significantly improve multicast performance compared to other schemes, and at the same time guarantee high PRR for all clients.

Cloudlet- and NFV-based carrier Wi-Fi architecture for a wider range of services

Over the past few years, Wireless Local Area Networks (WLANs) have been extensively deployed and have significantly evolved. However, the deployment of large-scale WLAN still presents management issues. Moreover, while newer WLAN technologies and services have been emerging at a prolific rate, the architecture of WLAN networks has been quite static and has seen difficulties to evolve. In this paper, we present a novel architecture for carrier-managed WLAN networks which leverages Network Function Virtualization concepts and virtualization technology in general. It is based on a WLAN Cloudlet which offloads MAC layer processing from access points and consolidates network functions and value-added services. All these functions and services are based on software instances. This brings more flexibility and adaptability and allows operators to easily implement new services while reducing CAPEX/OPEX and network equipment costs (e.g., access points).

Ensuring Predictable Contact Opportunity for Scalable Vehicular Internet Access on the Go

With increasing popularity of media-enabled handhelds and their integration with the in-vehicle entertainment systems, the need for high-data-rate services for mobile users on the go is evident. This ever-increasing demand of data is constantly surpassing what cellular networks can economically support. Large-scale wireless local area networks (WLANs) can provide such a service, but they are expensive to deploy and maintain. Open WLAN access points, on the other hand, need no new deployments, but can offer only opportunistic services, lacking any performance guarantees. In contrast, a carefully planned sparse deployment of roadside WiFi provides an economically scalable infrastructure with quality-of-service assurance to mobile users. In this paper, we present a new metric, called Contact Opportunity, to closely model the quality of data service that a mobile user might experience when driving through the system. We then present efficient deployment algorithms for minimizing the cost for ensuring a required level of contact opportunity. We further extend this concept and the deployment techniques to a more intuitive metric-the average throughput-by taking various dynamic elements into account. Simulations over a real road network and experimental results show that our approach achieves significantly better cost versus throughput tradeoff in both the worst case and average case compared to some commonly used deployment algorithms.

Extensions of Access-Point Aggregation Algorithm for Large-scale Wireless Local Area Networks

Recently, many organizations such as universities and companies have deployed wireless local area networks (WLANs) to cover the whole site for ubiquitous network services. In these WLANs, wireless access-points (APs) are often managed independently by different groups such as laboratories or departments. Then, a host may detect signals from multiple APs, which can degrade the communication performance due to radio interferences among them and increase operational costs. Previously, we proposed the AP aggregation algorithm to solve this problem by minimizing the number of active APs through aggregating them using the virtual AP technology . However, our extensive simulations in various instances found that 1) the minimization of active APs sometimes excessively degrades the network performance, and 2) the sequential optimization of host associations does not always reach optimal where slow links are still used. In this paper, we propose two extensions of the AP aggregation algorithm to solve these problems by 1) ensuring the minimum average throughput for any host by adding active APs and 2) further optimizing host associations by changing multiple hosts simultaneously in the host association finalization phase. We verify the effectiveness through simulations in four network instances using the WIMNET simulator.Â

TDOCP: A two-dimensional optimization integrating channel assignment and power control for large-scale WLANs with dense users

In order to improve the throughput of high-density and large-scale wireless local area networks (WLANs), a novel heuristic algorithm Two-DimensionalOptimization IntegratingChannel Assignment andPower Control (TDOCP) is proposed. Based on the traffic characteristic analyzed from real network, we take both uplink and downlink traffic into account in network modeling. The analysis of network utility shows that it has a controllable upper bound. So this paper develops a scheme to maximize the upper bound of network utility, and then make network utility converge to the enhanced upper bound. Both channel assignment (CA) and power control (PC) are performed in each iteration. To illustrate the advantages of TDOCP, a compared algorithm One-DimensionalOptimization IntegratingChannel Assignment andPower Control (ODOCP) is designed, which implements the least congested channel search (LCCS) in CA, and the power control for AP performance (PCAP) in PC. Only one-dimensional optimization is implemented in each iteration of ODOCP. Extensive simulations show that the network model in this paper is effective, and TDOCP outperforms current popular one-dimensional optimization algorithms LCCS, PCAP, and the compared ODOCP in the aspect of increasing throughput and reducing network delay.

OVERVIEW OF WIRELESS NETWORK CONTROL PROTOCOL IN SMART PHONE DEVICES

The computer network connection without wire or any cable is referring as wireless network. These wireless local area networks are popular for its worldwide applications. It has covered wide scale wireless local area network. The large scale systems to all applicable areas make large numbers of wireless termination and covering very much area. To reduce the complexity associated with server management, Information Technology organizations begins the process of centralizing servers. It used with architecture principles of centralized management requirement for network to scale, network architecture needs to be able to support enhanced services in addition to just raw connectivity, distributed processing is required both for scalability ability and services, network support continuously increase the level of throughputs etc. Wireless LAN product architectures have evolved from single autonomous access points to systems, consisting of a centralized Access Controller and Wireless Termination Points. The basic goal of centralized control architectures is to move access control, including user authentication and authorization, mobility & radio management, from one access point to centralized controller. The Wireless network Control Protocol allows for access and control of large-scale wireless local area networks. It can allows management of these networks, Control and Provisioning of Wireless Access Points In computer networking, a wireless access point is a device that allows wireless devices to connect to wired network using Wi-Fi, Bluetooth or related standards. The WAP usually connects to a router via a wired network, and can relay data between the wireless devices such as computers or printers and wired devices on the network.

OVERVIEW OF WIRELESS NETWORK CONTROL PROTOCOL IN SMART PHONE DEVICES

The computer network connection without wire or any cable is referring as wireless network. These wireless local area networks are popular for its worldwide applications. It has covered wide scale wireless local area network. The large scale systems to all applicable areas make large numbers of wireless termination and covering very much area. To reduce the complexity associated with server management, Information Technology organizations begins the process of centralizing servers. It used with architecture principles of centralized management requirement for network to scale, network architecture needs to be able to support enhanced services in addition to just raw connectivity, distributed processing is required both for scalability ability and services, network support continuously increase the level of throughputs etc. Wireless LAN product architectures have evolved from single autonomous access points to systems, consisting of a centralized Access Controller and Wireless Termination Points. The basic goal of centralized control architectures is to move access control, including user authentication and authorization, mobility & radio management, from one access point to centralized controller. The Wireless network Control Protocol allows for access and control of large-scale wireless local area networks. It can allows management of these networks, Control and Provisioning of Wireless Access Points In computer networking, a wireless access point is a device that allows wireless devices to connect to wired network using Wi-Fi, Bluetooth or related standards. The WAP usually connects to a router via a wired network, and can relay data between the wireless devices such as computers or printers and wired devices on the network

Wireless LAN Security Management with Location Detection Capability in Hospitals

In medical institutions, unauthorized access points and terminals obstruct the stable operation of a large-scale wireless local area network (LAN) system. By establishing a real-time monitoring method to detect such unauthorized wireless devices, we can improve the efficiency of security management. We detected unauthorized wireless devices by using a centralized wireless LAN system and a location detection system at 370 access points at the University of Tokyo Hospital. By storing the detected radio signal strength and location information in a database, we evaluated the risk level from the detection history. We also evaluated the location detection performance in our hospital ward using Wi-Fi tags. The presence of electric waves outside the hospital and those emitted from portable game machines with wireless communication capability was confirmed from the detection result. The location detection performance showed an error margin of approximately 4 m in detection accuracy and approximately 5% in false detection. Therefore, it was effective to consider the radio signal strength as both an index of likelihood at the detection location and an index for the level of risk. We determined the location of wireless devices with high accuracy by filtering the detection results on the basis of radio signal strength and detection history. Results of this study showed that it would be effective to use the developed location database containing radio signal strength and detection history for security management of wireless LAN systems and more general-purpose location detection applications.

Agent-Based Optimization for Large Scale WLAN Design

The complex nature of wireless local area networks (WLAN) design has led many of the deployments being done in an ad-hoc fashion without efficient design methodologies. Although this approach may work for a small environment with a small number of access points, it is infeasible to use such a process when designing a larger wireless infrastructure. Due to the low cost that is indicative of WLAN deployments, many practitioners view formal optimization techniques as being too complex and costly to implement. There have been a number of research works that investigate the use of formal optimization techniques for the accurate design of a WLAN. Unfortunately, the approaches taken do not address one major issue when designing a complex and demanding wireless network infrastructure, namely scalability. An optimization algorithm must consider a multitude of design criteria and therefore needs to be scalable to be successfully applied to large scenarios. The main contribution of the work presented in this paper is the development of a scalable optimization algorithm based on the tools of distributed artificial intelligence, which overcomes the failings of current approaches and can be utilized for WLAN design regardless of size or complexity of site specific requirements.

Gateway Deployment optimization in Cellular Wi-Fi Mesh Networks

With the standardization of IEEE 802.11, there has been an explosive growth of wireless local area networks (WLAN). Recently, this cost effective technology is being developed aggressively for establishing metro-scale “cellular Wi-Fi” network to support seamless Internet access in the urban area. We envision a large scale WLAN system in the future where Access Points (APs) will be scattered over an entire city enabling people to use their mobile devices ubiquitously. The problem addressed in this paper involves finding the minimum number of gateways and their optimal placement so as to minimize the network installation costs while maintaining reliability, flexibility and an acceptable grade of service. The problem is modeled taking a network graph, where the nodes represents either the Access Points of IEEE 802.11 or wired backbone gateways. In this paper, we present two methods (1) an innovative approach using integer linear programming (ILP) for gateway selection in the cellular Wi-Fi network, and (2) a completely new heuristic (OPEN/CLOSE) to solve the gateway selection problem. In the ILP model, we developed a set of linear inequalities based on various constraints. The ILP model is solved by using lp-solve, a simplex-based software for linear and integer programming problems. The second approach is an OPEN/CLOSE heuristic, tailored for cellular Wi-Fi, which arrives at a sub-optimal solution. Java programming language is used for simulation in OPEN/CLOSE heuristic. Extensive simulations are carried out for performance evaluation. Simulation results show that the proposed approaches can effectively identify a set of gateways at optimal locations in a cellular Wi-Fi network, resulting in an overall cost reduction of up to 50%. The technique presented in this paper is generalized and can be used for gateway selection for other networks as well.