Ahmed Hasswa

Handoffs in fourth generation heterogeneous networks

As mobile wireless networks increase in popularity and pervasiveness, we are faced with the challenge of combining a diverse number of wireless networks. The fourth generation of wireless communications is expected to integrate a potentially large number of heterogeneous wireless technologies in what could be considered a huge step forward toward universal seamless access. One of the main challenges for seamless mobility is the availability of reliable horizontal (intrasystem) and vertical (intersystem) handoff schemes. Efficient handoff schemes enhance quality of service and provide flawless mobility. This article presents different and novel aspects of handoff and discusses handoff related issues of fourth generation systems. Desirable handoff features are presented. Handoff decisions, radio link transfer, and channel assignment are described as stages of the complete handoff process. A vertical handoff decision function, which enables devices to assign weights to different network parameters, is also presented

Tramcar: A Context-Aware Cross-Layer Architecture for Next Generation Heterogeneous Wireless Networks

Major research challenges in the next generation (4G) of wireless networks include the provisioning of worldwide seamless mobility across heterogeneous wireless networks, the improvement of end-to-end Quality of Service (QoS) and enabling users to specify their personal preferences. Under this motivation, we design a novel cross-layer architecture that provides context-awareness, smart handoff and mobility control in heterogeneous wireless IP networks. We develop a Transport and Application Layer Architecture for vertical Mobility with Context-awareness (Tramcar). Tramcar is tailored for a variety of different network technologies with different characteristics and has the ability of adapting to changing environment conditions and unpredictable background traffic. Furthermore, Tramcar allows users to identify and prioritize their preferences. Simulation results demonstrate that Tramcar increases user satisfaction levels and network throughput under rough network conditions and reduces overall handoff latencies.

Generic vertical handoff decision function for heterogeneous wireless

As mobile wireless networks increase in popularity and pervasiveness, we are facing the challenge of integration of diverse wireless networks such as WLANs and WWANs. Consequently, it is becoming progressively more important to arrive at a vertical handoff solution where users can move among various types of networks efficiently and seamlessly. The ability to remain connected as a mobile device roams across different types of networks still remains an unachieved objective. Frequently, just choosing the best network to connect to, is a challenging problem due to the large number of network characteristics that need to be considered. Identifying these decision factors is therefore one of the principal objectives for seamless mobility. In this paper, we discuss the different factors and metric qualities that give an indication of whether or not a handoff is needed. We then describe a vertical handoff decision function, VHDF, which enables devices to assign weights to different network factors such as monetary cost, quality of service, power requirements, personal preference, etc.

A seamless context-aware architecture for fourth generation wireless networks

The integration of a multitude of wireless networks is expected to lead to the emergence of the fourth generation (4G) of wireless technologies. Under the motivation of increasing the levels of user satisfaction while maintaining seamless connectivity and a satisfactory level of QoS, we design a novel cross-layer architecture that provides context-awareness, smart handoff and mobility control in heterogeneous wireless IP networks. We develop a Transport and Application Layer Architecture for vertical Mobility with Context-awareness (Tramcar). Tramcar presents a new approach to vertical handoff decisions, which is not exclusively based on network characteristics but also on higher level parameters which fall in the application and transport layers. Tramcar is tailored for a variety of different network technologies with different characteristics and has the ability of adapting to changing environment conditions and unpredictable background traffic. Furthermore, Tramcar allows users to identify and prioritize their preferences. Tramcar is a smart and practical system, which is more capable of dealing with 4G challenges. Simulation results demonstrate that Tramcar increases user satisfaction levels and network throughput under rough network conditions and reduces overall handoff latencies.

Routeguard: an intrusion detection and response system for mobile ad hoc networks

As wireless networks increase in pervasiveness and popularity, it is becoming more important to have an effective intrusion detection and response solution. Wireless ad hoc networks are particularly vulnerable to denial of service attacks (DoS) due to their open decentralized architecture, highly dynamic topology and shared wireless medium in which they exist. One of the primary concerns with respect to ad hoc networks is to provide secure communication among mobile nodes in a hostile environment. In this paper, we propose a novel intrusion detection and response system called Routeguard. Routeguard employs a smart and smooth architecture in order to effectively discover malicious nodes and then proceeds to protect the network. The presented intrusion detection scheme produces a more natural system, which is more capable of dealing with malicious or suspected nodes. Simulation results demonstrate that this scheme improves network throughput by smartly classifying the nodes into different categories depending on their current actions and previous history.

Performance evaluation of a transport layer solution for seamless vertical mobility

Major research challenges in the next generation of wireless networks include the provisioning of worldwide seamless mobility across heterogeneous network interfaces and the improvement of end to end quality of service. The integration and interoperability of the multitude of available networks will lead towards the emergence of the fourth generation of wireless networks. In this paper we introduce a transport layer mobility solution that supports roaming of a mobile host without any necessary modifications to the underlying network and data link layers. A modified version of the new IETF transport protocol, SCTP, is shown to improve the handoff latency and delay. Using simulation results, we show that a noticeable improvement in performance is possible by monitoring the accessible networks, and making the appropriate handoff decisions. Furthermore, we prove that a higher level of user preferences and context awareness can be achieved with the employment of our scheme.

On Extending IMS Services to WLANs

The IP multimedia subsystem (IMS) provides a framework that accommodates current and future services in wired and wireless networks. However, IMS does not handle non-3G elements such as wireless local area networks (WLANs). In order to provide interconnection at the service layer between 3G and WLANs, interworking between IMS and WLAN is necessary. Extending IMS beyond 3G to WLANs is a crucial step towards the evolution of a seamless universal next generation wireless network, commonly known as 4G. In this paper, a novel architecture for service layer interworking between WLAN and 3G is presented. The architecture takes into consideration the interaction of WLAN Application SIP servers with the IMS call session control functions (CSCFs) and the extensibility of application servers (ASs) beyond the core IMS network. A WLAN AS is introduced into the IMS network and an SIP server into the WLAN. These act as interworking arbitrators and communicate with each other to provide service and session continuity. The main advantage of this architecture is its feasibility within the standard. It is also non-intrusive to the IMS core or the WLAN.

A smart spaces architecture based on heterogeneous contexts, particularly social contexts

Advances in smart technologies, wireless networking, and the increased interest in services have led to the emergence of ubiquitous and pervasive computing as one of the most promising areas of computing in recent years. Researchers have become specifically interested in smart spaces and the significant improvements it can introduce to our lives. Most smart spaces rely on physical components such as sensors to sense and acquire information about the real world environment and surroundings. Although sensor networks can provide useful contextual information, they are known for their high degree of unreliability and limited resources.We believe that it is necessary to augment physical sensors with other kinds of data to create more reliable and truly context-aware smart spaces. In this paper we therefore utilize mobile devices and social networks to acquire more detailed and useful contextual information that can help create smarter spaces. We then propose a smart spaces architecture that utilizes these new contexts and in particular the social context.

Using heterogeneous and Social Contexts to create a smart space architecture

Advances in smart technologies, wireless networking, and the increased interest in services have led to the emergence of ubiquitous and pervasive computing as one of the most promising areas of computing in recent years. Smart Spaces in particular have gained a lot of interest within the research community. Most smart spaces rely on physical components such as sensors to sense and acquire information about the real world environment. Although sensor networks can provide useful contextual information, they are known for their high degree of unreliability and limited resources. We believe that it is necessary to augment physical sensors with other kinds of data to create more reliable and truly context-aware smart spaces. In this paper we therefore utilize mobile devices and social networks to acquire more detailed useful contextual information that can help create smarter spaces. We then propose a Smart Spaces architecture that utilizes these new contexts and in particular the Social context.

Managing Presence and Policies in Social Network dependent systems

Social Networks have recently experienced a significant increase in popularity and are now an integral part of millions of peoples daily lives. Through these Social Networks, users create profiles, build relationships, and join groups forming intermingled sets and communities. There is a wealth of information within Social Networks, which if exploited properly and combined with rules and policies, can lead to a whole new level of smart contextual services. A mechanism is therefore needed to extract data from heterogeneous Social Networks, link profiles across different networks and aggregate the data obtained. We design a Presence and Policies Server that manages the information exchange between Social Networks, services and the environment and passes along the relevant information and rules to different entities. The Presence and Policies server is capable of querying, importing and aggregating data from across multiple Social Networks and services and then converting that data into standardized semantic information that can be interpreted and translated into meaningful information by other users and services.