Current Research Projects @ WiNG

A brief summary of research projects that are currently being carried out at the WiNG are summarized on this page. Further information may be obtained by contacting WiNG leader. For the summary of previous research projects, please see other parts of the webpage.

· Multi-layer and Cognitive Wireless Mesh Networks

Wireless Mesh Networks (WMN) have been introduced as a promising technology towards forming the backbone of the next generation Internet. The main elements of a WMN are mesh routers and mesh clients, where the interconnected mesh routers with multiple interfaces form the backbone network providing connectivity to the neighboring routers and clients. Achieving acceptable quality of service (QoS) levels requires distributed control over the network resources, and subsequent awareness of the dynamically changing conditions of the WMN. As part of this project, for facilitating such control, a cognitive mechanism is introduced, which facilitates cooperation among multiple mesh routers and edge routers for routing clients traffic. The aim of the cognition is to fairly maximize the fulfillment of the clients from the achieved QoS (i.e., delay, data rate, packet loss). This control is gained through observing and learning the network behavior, and finally deciding on the distribution of the traffic into multiple paths. Further in this project, a novel technique is designed for routing the particular type of traffic, which is sensitive to both packet loss and delay. This robustness against packet loss (due to link and node failures) is gained by cognitively sending copies of packets through multiple mesh paths, while the selection of paths is formulated in a way that redundant packets do not result in network congestion.

· A Unified Mobility Management Architecture for Interworked Heterogeneous Mobile Networks

The buzzword of this decade has been convergence. Thus the future Next Generation Mobile Network (NGMN) is envisioned as a group of co-existing heterogeneous wireless mobile data networking technologies sharing a common Internet Protocol (IP) based backbone. In such all-IP based heterogeneous networking environments, ongoing sessions are subjected to frequent vertical handoffs. Therefore, ensuring uninterrupted service continuity during session handoffs requires successful architectures, protocols, and standards to be implemented in these participating access networks. This research introduces a common interworking framework for ensuring seamless service continuity over dissimilar networks. Hence the key achievements of this project can be stated as: to propose a mobility-aware novel architecture for interworking between heterogeneous mobile data networks and to propose a framework for facilitating unified real-time session management across these different networks. This interworking framework is capable of interworking 3G cellular technologies (e.g., UMTS and CDMA2000), Wireless Local Area Networking (WLAN) technologies, and Wireless Metropolitan Area Networking (WMAN) technologies (e.g., WiMAX) under a common signaling platform. It is also a pioneering project where the IP Multimedia Subsystem (IMS) is used as a universal coupling mediator for real-time session negotiation and management. As a result, it enables a roaming user to seamlessly handoff sessions between different heterogeneous networks. Another significant contribution of this project is the proposal put forward for harmonizing two international mobile communication standards, i.e., the 3rd Generation Partnership Project (3GPP) standard and the 3rd Generation Partnership Project 2 (3GPP2) standard.

· Network Mobility Support for Interworked Heterogeneous Mobile Networks

The future Next Generation Mobile Network (NGMN) is envisioned as a group of co-existing heterogeneous wireless mobile data networking technologies sharing a common Internet Protocol (IP) based backbone. As a result, it enables a roaming user to seamlessly handoff sessions between different heterogeneous networks, thus giving the opportunity of anywhere, anytime, connectivity on the go. For example, users are now able to check their emails on the bus or watch online news while travelling in the train. Therefore, as a result of ubiquitous service access, group mobility scenarios have emerged. To this effect, the existing session mobility management mechanisms need to be extended for supporting group mobility in NGMNs. Having understood this importance, the IETF has recently standardized a framework called NEtwork MObility (NEMO) basic support protocol (RFC 3963) for a set of users moving as a unit. However, much work needs to be done for extending the NEMO framework for supporting a heterogeneous networking environment, or the NGMN. Therefore, this project aims towards integrating the NEMO framework to NGMN architecture to enable group mobility management between heterogeneous networks. The expected benefits of this project are power saving, low complexity, low cost, and reduced handoff latency to both end users and service providers.

· Cross-correlated Security and QoS in Heterogeneous Mobile Networks

The aspiration of this research is to address both the security and Quality of Service (QoS) aspects of heterogeneous networks concurrently. Our main approach is to consider the security aspect as a Quality of Service (QoS) parameter, and thereby managing the security of the network in conjunction with other QoS metrics. Approaching security under the family of QoS would not only simplify its implementation when administering interconnection over heterogeneous networks, but also avoid having to sacrifice QoS metrics for the sake of another as they are implemented on a common platform. In order to achieve this objective, a generic security framework for the heterogeneous environment is going to be developed. Once the security framework is defined, a novel network attack detection technique will be proposed for detecting and capturing malicious network attacks such as denial of service (DoS) and distributed DoS (DDoS). The proposed detection technique will incorporate several prominent QoS parameters as its control parameters, thus enables the correlation between the security and QoS requirements. Besides the aforementioned aspects (i.e., security and QoS), it is crucial to ensure that the proposed framework and associated protocols or algorithms remain scalable to new Internet applications and services.

· Cooperative Cellular Networks

Conventional cellular systems have provided voice services since the introduction of the first analog systems. In the last decade, with the increased demand of access, the types of services supported by cellular networks have also expanded from simple voice to multimedia services such as video conferencing. These new services in conjunction with the wireless access to the Internet generate more bursty and unbalanced traffic than conventional voice traffic. It is therefore expected that the probability of having congestion in the next generation systems will be high. In other words, even though the traffic load does not reach the maximum capacity of the entire system, a significant number of calls will be dropped or blocked due to localized congestion.

Recently there has been some interest in integrating multi-hop relaying functionalities into cellular wireless networks to overcome this problem. However, none of these architectures consider cooperative communications. The notion of cooperative communication is to enable transmitting and receiving cooperatively at user level by exploiting the broadcast nature of wireless radio waves. The purpose of this project is to address the important problem of how to evolve from the existing heavily invested cellular infrastructure to next generation cooperative systems that scale well with the number of mobile hosts and, in particular, overcome the congestion by dynamically balancing the load among different cells in a cost effective way.

· Opportunistic Mobile Ad Hoc Networks

Opportunistic mobile ad hoc networks (also referred to as intermittently connected mobile ad hoc networks (ICMANs)) are one of main evolutions of mobile ad hoc networks. In ICMANs, due to node mobility, sporadic node density, short transmission range, and so on, there is no assumption about a complete path existing between two nodes wishing to communicate. Thereby in the ICMANs context, the mobility and storage space of the intermediate mobile nodes have to be employed to bring the message closer to its eventual destination. Therefore, applications over ICMANs must tolerate extra introduced delays. To this effect, ICMANs are a type of delay tolerant networks (DTNs). The topic of DTN services is still at its early stages. Therefore, our project aims to develop a feasible content distribution network over ICMANs. This content distribution network should provide efficient content dissemination and content search under the restricted resource conditions such as storage spaces and link bandwidths. In addition, the underlying routing protocol for ICMANs is investigated as well.

· Inter-Vehicular Communications Networks

As part of the research in the field of inter-vehicular communication networks, this work focuses on improving the performance of the safety message broadcasting in Vehicular ad-hoc Networks (VANETs). In the IEEE 802.11 based vehicular networks, broadcast storms, neighboring interferences, and packet collisions may lead to failure of receiving safety messages, particularly under high density vehicular traffic conditions. Unfortunately, the current safety message broadcasting schemes are unable to address these issues. Our main approach is to consider variable broadcasting transmission range and topology changes aspects as the performance improvement parameters. The change in broadcasting transmission range control is based on categorizing safety messages according to their danger level. Each safety category assigns a unique transmission range according to the emergent level. Furthermore, we group vehicles into clusters, where each cluster has a cluster head to manage safety message broadcasting in its domain and rebroadcast safety message from neighbor clusters. The proposed broadcasting framework can reduce the broadcast storm and message collisions and improves the performance of safety message dissemination in VANETs.

· Data Aggregation Techniques in Wireless Sensor Networks

Recent advances in technology make it feasible to mass produce small sensor nodes with sensing, computation, and communication capabilities. Protocols for sensor networks should be carefully designed so as to make the most efficient use of the limited resources especially for energy. Development of data aggregation techniques is thought as an effective way to save energy in order to prolong the lifetime of Wireless Sensor Networks (WSNs). Particular characteristics of data gathered from spatial-temporal domain may represent certain level of correlation among data values. Based on this observation, analyzing and exploit the correlation is an efficient way to remove the redundancy information. A cross-layer approach to design WSNs is likely to be needed for optimal performance. Application oriented aggregation methods are investigated for different scenarios, such as data harvesting and event detection. The effects of complicate environment are considered in the practical problems for WSN systems.

· MAC Framework for Cognitive Radio Networks

The aim of this project is to investigate and develop MAC layer techniques that will assist in the deployment of Cognitive Radio (CR) Networks in various environments, and for various purposes. The following areas will be examined as part of this research: Cognitive Radio Link layer control, Flow scheduling in Cognitive Radio environments, Cognitive Radio Power control, Cross layer design, QoS Maintenance in Primary and Cognitive Radio users.

Link Layer Control research includes the design of the medium access scheme, incorporating spectrum sensing, sensing scheduling, channel decision and channel reservation. The aim is to jointly consider these issues that are required for effective operation of Cognitive Radio Networks, and to construct and effective MAC protocol for different applications, including Intermittently Connected Networks. Flow Scheduling and Power Control research will examine recent developments in both areas for as applied to Cognitive Radio systems, and develop methods to apply them to various operating environments and network configurations. Joint Power Control and Scheduling design and Optimization methods will also be examined and applied.

Cross Layer Design research includes methods of optimizing the operation of Physical, MAC and Network layer methods by considering the relationships between them. QoS Maintenance research will include methods of QoS guarantee provision by Cognitive Radio Networks (also considering Power and Scheduling), as well as the effect of Cognitive Radio operation on Primary User QoS. Methods of guaranteeing Primary user QoS and appropriate compensation for lost QoS including spectrum access pricing methods for different Primary and Cognitive radio users.