Abstract—In this paper, we present experimental studies on the throughput of IEEE 802.11b wireless networks for UDP and VoIP traffic. Our experiments show that the maximum data throughput of a single station sending out UDP traffic is 6.1 Mbps. The maximum number of VoIP calls in a single cell of an IEEE 802.11b network is six if the ITU G711a-Law codec is used with 10 milliseconds of audio data per RTP packet. The experiments also show that the effective available bandwidth in the wireless network is reduced by ongoing VoIP connections. Specifically, for the above codec settings, each VoIP connection reduces the bandwidth available for data traffic by 900 Kbps. I.

Location-based Access Control (LBAC) techniques allow taking users' physical location into account when determining their access privileges. In this paper, we present an approach to LBAC aimed at integrating location-based conditions along with a generic access control model, so that a requestor can be granted or denied access by checking her location as well as her credentials. Our LBAC model includes a novel way of taking into account the limitations of the technology used to ascertain the location of the requester. Namely, we describe how location verification can be encapsulated as a service, representing location technologies underlying it in terms of two semantically uniform service level agreement (SLA) parameters called confidence and timeout. Based on these parameters, we present the formal definition of a number of location-based predicates, their management, evaluation, and enforcement. The challenges that such an extension to traditional access control policies inevitably carries are discussed also with reference to detailed examples of LBAC policies.

Location-based Access Control (LBAC) techniques allow the definition of users ’ access rights based on location predicates that exploit the users ’ physical location. However, evaluating the physical location of a user is a specialized activity that is unlikely to be performed by the same entity (e.g., organization or system) in charge of the access control decision. For this reason, location evaluation is usually assumed to be provided by specific Location Services (LSs) possibly coexisting in a same area and competing one with the others. In this paper, we address the issues related to the communication and negotiation between an Access Control Engine (ACE) enforcing access rules that include location-based predicates and multiple, functionally equivalent, LSs. We introduce metadata for the exchange of service level agreement attributes between the ACE and the LSs. Based on such metadata we develop different negotiation protocols, from a basic negotiation protocol that shows the core aspects of our proposal to an enhanced protocol that enriches the interaction by taking into account a cost/benefit analysis and some service requirements. Finally, we present an extension to the enhanced protocol to consider possible time validity constraints on access control decisions.

Recent technological advances have made it feasible to measure and track the location of users, vehicles, and practically any mobile object. Positioning and tracking systems are then collecting a huge amount of potentially sensitive location information, which is a set of data describing a user’s location over a period of time. Since the activities of a user are often related to the locations where such activities are performed, it is natural for users to demand privacy, that is, to require control over the access to their location information. In this chapter, we focus on the privacy aspects of using location information in location-based services (LBSs). LBSs are services that take the current position of the user into consideration when performing their tasks. These services can be accessed from mobile phones, PDA, and any other mobile device. We start the chapter by characterizing the location privacy protection problem and introducing a classification of the main techniques that have been proposed to protect the location privacy. We also survey and discuss recent proposals and ongoing work in the location-based systems area. 1

Abstract. Recent enhancements in location technologies reliability and precision are fostering the development of a new wave of applications that make use of the location information of users. Such applications introduces new aspects of access control which should be addressed. On the one side, precise location information may play an important role and can be used to develop Location-based Access Control (LBAC) systems that integrate traditional access control mechanisms with conditions based on the physical position of users. On the other side, location information of users can be considered sensitive and access control solutions should be developed to protect it against unauthorized accesses and disclosures. In this chapter, we address these two aspects related to the use and protection of location information, discussing existing solutions, open issues, and some research directions. 1

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The proposed research aims to provide the technical framework which will enable multiple Wireless LANs to provide the assured network service while being in communication range of each other. The Access Points involved compete and cooperate while keeping the overall goal of maximum system utilization above individual optimization. We use channel access time as the means of resource allocation, while keeping the system modular so that any other unit can also be used without changing the protocol. We provide a secondary protocol to ensure robustness of our main algorithm for Access Allocation. We also

So as to guarantee the fairness of electronic transactions, users may require a NonRepudiation (NR) service in any type of network. However, most existing NR protocols cannot work properly in a Mobile Ad hoc Network (MANET) due to their characteristics (e.g. limited resources and lack of central authority). The design of the Probabilistic NonRepudiation Protocol (PNRP) is comparatively suitable for the nature of a MANET, but it still poses some QoS issues. This article points out the QoS issues which are caused by using PNRP in a MANET environment. These issues explain the difficult of performing PNRP in such an infrastructureless environment.