Farooq Bari

Automated network selection in a heterogeneous wireless network environment

Service delivery in a heterogeneous all-IP wireless network environment requires the selection of an optimal access network. Selection of a non-optimal network can result in undesirable effects such as higher costs or poor service experience. Network selection in such an environment is influenced by several factors, and currently a complete solution is not available to solve this problem. This article describes a comprehensive decision making process to rank candidate networks for service delivery to the terminal. The proposed mechanism is based on a unique decision process that uses compensatory and non-compensatory multi-attribute decision making algorithms jointly to assist the terminal in selecting the top candidate network

Multi-Attribute Network Selection by Iterative TOPSIS for Heterogeneous Wireless Access

Contemporary multimedia consumer devices are increasingly obtaining network connectivity mostly through wireless means. In order to economically support the mobile lifestyle of users, a new class of multimodal consumer devices has emerged that are equipped with heterogeneous wireless access capability. Inter-working of heterogeneous packet switched wireless networks, e.g., cellular and WLANs, via IP is a key step to provide ubiquitous service delivery via seamless connectivity of consumer devices. These wireless networks have a diverse range of capabilities and therefore selection of a specific network to optimize service delivery is an issue. Various algorithms have been proposed for use in the decision making process, with the class of Multi Attribute Decision Making (MADM) methods being one of the most promising. MADM methods, however, are known to suffer from ranking abnormalities. This paper applies TOPSIS, a MADM algorithm, to the problem of network selection. The causes of ranking abnormalities in TOPSIS are analyzed. An improvement to the algorithm as applied to the problem of network selection, where only the top ranking alternatives are considered important for decision making, is proposed. The new approach iteratively applies TOPSIS to the problem, removing the bottom ranked candidate network after each iteration. Simulation results are presented to demonstrate the effectiveness of the proposed iterative TOPSIS approach.

Service delivery over heterogeneous wireless systems: networks selection aspects

The problem of service delivery over heterogeneous wireless access networks is quite complex and is a topic of ongoing research. Although a unifying aspect of current packet based wireless access technologies is that all of them support IP transport, a common architecture that would allow a mix of autonomous heterogeneous wireless networks to coexist and inter work to provide ubiquitous service using the best network for service delivery at any location does not currently exist. Such a common architecture is essential to enable interoperability across autonomous wireless systems. This paper provides components of a common architectural solution that enables automatic network selection at user terminals with network assistance. It defines new network layer nodes along with new functionality for some of the existing nodes in current systems. A concept of directory assistance type of functionality is introduced where the network could inform the user terminal about the best suited network for the requested service. The proposed architecture allows the user terminal to intelligently and automatically select the network, based on several parameters including service to be used, network QoS capabilities and current network conditions. The proposed architecture is flexible and would enable a variety of business models through different deployment scenarios.

Use of non-monotonic utility in multi-attribute network selection

Network convergence across different access technologies holds a promise of enabling ubiquitous service availability but faces several technical challenges. With anticipated proliferation of multimode IP devices, the optimal selection of a service delivery network among multiple IP based wireless access alternatives is one of the important issues that is actively studied and discussed in several standardization forums. Use of multi attribute decision making (MADM) algorithms has been proposed in the past for network selection decisions in a heterogeneous wireless network environment. A direct comparison of these algorithms is difficult as this would require the use of another MADM algorithm. A better approach instead is to ascertain the appropriateness of the algorithm to the problem space. This paper provides the basis for evaluating the appropriateness of MADM algorithms for network selection. It analyzes the use of MADM algorithms such as TOPSIS, ELECTRE and GRA for network selection and argues that GRA provides the best approach in scenarios where the utilities of some of the attributes are non-monotonic. The paper proposes a novel stepwise approach for GRA that uses multiple reference networks and explains its working with network selection scenarios.

Architectural aspects of automated network selection in heterogeneous wireless systems

Next-generation heterogeneous wireless systems using an all-IP transport allow converged services such as those based on IP Multimedia Subsystem (IMS) to be delivered over a variety of access technologies. These services however require underlying access technologies to support certain capabilities like Quality of Service. For devices supporting multiple access technologies this results in a complex problem of selection of an optimal service delivery access network. This paper addresses the architectural aspects of the problem by enhancing the roles of policy related components defined in cellular standards and by combining them with novel network selection components to enable automated network selection.

An AAA based service customization framework for public WLANs

An important aspect of providing ubiquitous coverage is service portability to different access network technologies. Current public WLAN deployments lack enablers for a proper delivery of value added data services to which the user may have subscribed in his home cellular network. The paper addresses some of the challenges associated with delivering such value added data services over public WLANs. It suggests enhancements to the currently deployed public WLAN AAA infrastructure by separating user authentication from service authorization. It further proposes that the users home network get additional information from the public WLAN operator as part of the initial user authentication. This information can be used by the home network to authorize or customize home network based services delivered to the user. The proposed enhancements would leverage the existing WLAN AAA infrastructure for carrying this information.

Telecommunications standards: Part II [Guest Editorial]

Telecommunications is driving what is perhaps the most significant social revolution that mankind has ever known, changing the way people live, work, interact, and socialize. Telecommunications has been thus attracting ever increasing attention from researchers in both academia and industry. Although both communities have made great achievements and outstanding contributions to communications, these two domains are frequently unaware of the capacities, expertise, and challenges faced by the other.