Sirin Tekinay

A survey of game-theoretic approaches in wireless sensor networks

Wireless sensor networks (WSNs) comprising of tiny, power-constrained nodes are gaining popularity due to their potential for use in a wide variety of environments like monitoring of environmental attributes, intrusion detection, and various military and civilian applications. While the sensing objectives of these environments are unique and application-dependent, a common performance criteria for wireless sensor networks is prolonging network lifetime while satisfying coverage and connectivity in the deployment region. Security is another important performance parameter in wireless sensor networks, where adverse and remote environments pose various kinds of threats to reliable network operation. In this paper, we look at the problems of security and energy efficiency and different formulations of these problems based on the approach of game theory. The potential applicability of WSNs to intruder detection environments also lends itself to game-theoretic formulation of these environments, where pursuit-evasion games provide a relevant framework to model detection, tracking and surveillance applications. The suitability of using game theory to study security and energy efficiency problems and pursuit-evasion scenarios using WSNs stems from the nature of strategic interactions between nodes. Approaches from game theory can be used to optimize node-level as well as network-wide performance by exploiting the distributed decision-making capabilities of WSNs. The use of game theory has proliferated, with a wide range of applications in wireless sensor networking. In the wake of this proliferation, we survey the use of game-theoretic approaches to formulate problems related to security and energy efficiency in wireless sensor networks.

Cochannel interference computation and asymptotic performance analysis in TDMA/FDMA systems with interference adaptive dynamic channel allocation

It has been shown through simulation results that the interference adaptive dynamic channel allocation (IA-DCA) scheme is a promising resource allocation strategy in time/frequency-division multiple-access (TDMA/FDMA) communication systems. The major obstacle in analyzing IA-DCA is the computation of cochannel interference without the constraint of conventional channel reuse factors. To overcome this difficulty, one needs a computationally efficient representation which can approximate the interference distribution accurately. For this purpose, a concept called channel reuse zone (CRZ) is introduced. Based on this new concept, both downlink and uplink cochannel interference are computed with two different propagation models, namely, a simplified deterministic model and a shadowing model. The results are then used to calculate the outage probability of the idealized, interference adaptive maximum parking (IAMP) scheme. Finally, as a significant contribution, an asymptotic performance bound for the two-way IA-DCA strategy is derived.

Adaptive density control in heterogeneous wireless sensor networks with and without power management

The authors study the design of heterogeneous two-tier wireless sensor networks (WSNs), where one tier of nodes is more robust and computationally intensive than the other tier. The authors find the ratios of densities of nodes in each tier to maximise coverage and network lifetime. By employing coverage processes and optimisation theory, the authors show that any topology of WSN derived from random deployments can result in maximum coverage for the given node density and power constraints by satisfying a set of conditions. The authors show that network design in heterogeneous WSNs plays a key role in determining key network performance parameters such as network lifetime. The authors discover a functional relationship between the redundancy, density of nodes in each tier for active coverage and the network lifetime. This relationship is much less pronounced in the absence of heterogeneity. The results of this work can be applied to network design of multi-tier networks and for studying the optimal duty cycles for power saving states for nodes in each tier.

An adaptive location registration scheme with dynamic mobility classification

An adaptive location registration scheme is proposed for wireless cellular networks. A high speed mobile on a highly directed path does not need to update its location as long as the mobile maintains its speed and direction since the network can predict the location of the mobile using the mobiles speed and direction information. On the other hand, for a mobile doing a random walk, the location prediction using the speed and direction information is inefficient in terms of the signaling cost and prediction accuracy. With this observation, we dynamically classify mobiles based on the predictability of their trajectory. A mobile with predictable trajectory is prescribed a predictive distance-based location update scheme and a mobile with random trajectory is prescribed a (non-predictive) distance-based location update scheme. The performance of the adaptive scheme is compared with the predictive and non-predictive schemes.

Location based services for next generation wireless mobile networks

We study how wireless network can support location based services (LBS) a to mobile users. WE assume that each mobile is capable of self-geolocation using GPS and indoor geolocation [K. Pahlavan et al., Feb 2002]. The wireless network collects the geolocation information from mobiles and provides this information to application service so that the services can be custom-tailored for each mobile user. The main challenge in wireless network is to keep track of geolocation of mobile users so that the application service can maintain the quality of the service (QoS). In general, the quality of service depends on how often mobile terminals update their geolocation. Since geolocation update requires battery power and radio resource, optimizing the geolocation update frequency is critical. In this paper, we present geolocation update schemes that minimize the update frequency while satisfying the QoS of application service. For case study, we consider location based traffic report service (LBS-TR) and location based navigation service (LBS-NS). In LBS-TR, mobile users who are about to enter heavily jammed highways are informed in a timely manner so that the mobile users can avoid traffic congestion. In LBS-NS, mobile users are provided with navigation instructions that are custom-tailored to the geolocation of the users. The granularity of navigation instruction changes as the user moves from highway to local street and from local street into building complex.

Reducing transmit power and extending network lifetime via user cooperation in the next generation wireless multihop networks

In this paper, we introduce a new approach to the minimum energy routing (MER) for next generation (NG) multihop wireless networks. We remove the widely used assumption of deterministic, distance-based channel model is removed, and analyze the potentials of MER within the context of the realistic channel model, accounting for shadowing and fading. Rather than adopting the conventional unrealistic assumption of perfect power control in a distributed multihop environment, we propose to exploit inherent spatial diversity of mobile terminals (MT) in NG multi-hop networks and to combat fading using transmit diversity. We propose the cooperation among MTs, whereby couples of MTs cooperate with each other in order to transmit the signal using two MTs as two transmit antennas. We provide the analytical framework for the performance analysis of this scheme in terms of the feasibility and achievable transmit power reduction. Our simulation result indicate that significant gains can be achieved in terms of the reduction of total transmit power and extension of network lifetime. These gains are in the range of 20–100% for the total transmit power, and 25–90% for the network lifetime, depending on the desired error probability. We show that our analytical results provide excellent match with our simulation results. The messaging load generated by our scheme is moderate, and can be further optimized. Our approach opens the way to a new family of channel-aware routing schemes for multihop NG wireless networks in fading channels. It is particularly suitable for delivering multicast/geocast services in these networks.

Location-Based Service Provisioning for Next Generation Wireless Networks

We study how the wireless network infrastructure can support location-based services (LBSs). We assume that each mobile is equipped with self-geolocation capability. The wireless network can provide geolocation information of mobiles to an application services provider (ASP) so that the ASP can customize services based on the geolocation of the users. The main challenge in wireless networking is to keep track of the geolocation of mobile users such that the application service can maintain a certain quality of service (QoS). In general, the quality of service depends on how often mobiles update their geolocation. Because geolocation updates require battery power, radio resources, and signaling in the wired network, optimization of the geolocation update frequency is critical. In this paper, we present geolocation update schemes in which we can minimize the update frequency while satisfying the QoS of application service. For case study, we consider location-based traffic report service (LBS-TR) and location-based navigation service (LBS-NS). In LBS-TR, each mobile user about to enter a heavily jammed highway is informed in a timely manner so that the user can avoid traffic congestion. In LBS-NS, a mobile user is given navigation instructions custom-tailored to the geolocation of the user. The granularity of navigation instructions changes as the user moves from highway to local street and from local street to building complex.

A novel adaptive bandwidth allocation: wavelet-decomposed signal energy approach

Traffic measurements are key in the development of robust resource management and scheduling algorithms. Bandwidth allocation methods are either static or they adaptively change the bandwidth assigned to applications. Adaptive algorithms predict the near future behavior of traffic based on average queue size and utilization information to update the allocated bandwidth. This work introduces a novel feedback mechanism that uses wavelets and measures the energy of a byte counting process at the output of each dyadic subband filter. The output is then used to predict short and long term fluctuations in the incoming traffic pattern and to readjust the bandwidth allocation accordingly.

Performance evaluation framework and quality of service issues for mobile ad hoc networks in the MOSAIC ATD

This paper identifies and describes the issues facing quality of service (QoS) provisioning in multihop mobile ad hoc networks, particularly in tactical environments such as those described by the multifunctional on-the-move secure adaptive integrated communications (MOSAIC) advanced technology demonstration (ATD). The MOSAIC ATD focuses on integrating a highly adaptive communications infrastructure that supports the seamless flow of multi-media services across terrestrial and space based platforms using advanced QoS techniques, ad hoc networking, bandwidth management, and traffic scaling. The paper first discusses issues and challenges related to wireless communications in tactical mobile ad hoc networks and then describe some performance evaluation criteria that should be used to assess the capabilities of network protocols as they operate in such environments. It also identifies issues associated with QoS, presents some parameters that should be used to evaluate QoS support, and discusses some solutions in order to support QoS in ad hoc networks and wireless ATM. Finally it concludes with areas of future work that would be appropriate for the extension of QoS technologies.

Ad hoc enhanced routing in UMTS for increased packet delivery rates

Wireless communications is moving from cellular networks towards a more distributed, self-configuring ad hoc oriented networks. Until a complete metamorphosis occurs, the emerging techniques that allow communication by using no infrastructure at all can be enjoyed at the presence of the vast infrastructure of cellular systems. Alternatively, this situation can be viewed as the cellular systems of today benefiting from the flexible new techniques of ad hoc communications in order to improve current levels of performance. In this paper, we propose ad hoc routing techniques that allows improved packet delivery performance in the next generation of a UMTS system. Our results show that a hybrid network, where each mobile terminal is capable of communicating to a base station and to other mobile terminals in the network, and delivers packets much more successfully than the conventional UMTS network. Furthermore, the number of nodes that can be supported by such a system is much higher than the case of a pure cellular network. We construct 2 alternative routing schemes that exploit the hybrid architecture and show that performance is superior as compared to UMTS.