Coarse First Arriving Path Detection for Subscriber Location in Mobile Communication Systems

Publication in the conference proceedings of EUSIPCO, Toulouse, France, 200

Cramer-Rao bounds in the estimation of time of arrival in fading channels

This paper computes the Cramer-Rao bounds for the time of arrival estimation in a multipath Rice and Rayleigh fading scenario, conditioned to the previous estimation of a set of propagation channels, since these channel estimates (correlation between received signal and the pilot sequence) are sufficient statistics in the estimation of delays. Furthermore, channel estimation is a constitutive block in receivers, so we can take advantage of this information to improve timing estimation by using time and space diversity. The received signal is modeled as coming from a scattering environment that disperses the signal both in space and time. Spatial scattering is modeled with a Gaussian distribution and temporal dispersion as an exponential random variable. The impact of the sampling rate, the roll-off factor, the spatial and temporal correlation among channel estimates, the number of channel estimates, and the use of multiple sensors in the antenna at the receiver is studied and related to the mobile subscriber positioning issue. To our knowledge, this model is the only one of its kind as a result of the relationship between the space-time diversity and the accuracy of the timing estimation.Peer ReviewedPostprint (published version

HoPP: Robust and Resilient Publish-Subscribe for an Information-Centric Internet of Things

This paper revisits NDN deployment in the IoT with a special focus on the interaction of sensors and actuators. Such scenarios require high responsiveness and limited control state at the constrained nodes. We argue that the NDN request-response pattern which prevents data push is vital for IoT networks. We contribute HoP-and-Pull (HoPP), a robust publish-subscribe scheme for typical IoT scenarios that targets IoT networks consisting of hundreds of resource constrained devices at intermittent connectivity. Our approach limits the FIB tables to a minimum and naturally supports mobility, temporary network partitioning, data aggregation and near real-time reactivity. We experimentally evaluate the protocol in a real-world deployment using the IoT-Lab testbed with varying numbers of constrained devices, each wirelessly interconnected via IEEE 802.15.4 LowPANs. Implementations are built on CCN-lite with RIOT and support experiments using various single- and multi-hop scenarios

Effect of multiuser interference on subscriber location in CDMA networks

The last few years have witnessed an ever growing interest in the field of mobile location systems for cellular systems. The motivation is the series of regulations passed by Federal Communications Commission, requiring that wireless service providers support a mobile telephone callback feature and cell site location mechanism. A further application of the location technology is in the rapidly emerging field of intelligent transportation systems, which are intended to enhance highway safety, location based billing etc. Many of the existing location technologies use GPS and its derivatives which require a specialized subscriber equipment. This is not feasible for popular use, as the cost of such equipments is very high. Hence, for a CDMA network, various methods have been studied that use the cellular network as the sole means to locate the mobile station (MS), where the estimates are derived from the signal transmitted by the MS to a set of base station\u27s (BS) This approach has the advantage of requiring no modifications to the subscriber equipment. While subscriber location has been previously studied for CDMA networks, the effect of multiple access interference has been ignored. In this thesis we investigate the problem of subscriber location in the presence of multiple access interference. Using MATLAB as a simulation tool, we have developed an extensive simulation technique which measures the error in location estimation for different network and user configurations. In our studies we include the effects of log-normal shadow and Rayleigh fading. We present results that illustrate the effects of varying shadowing losses, number of BS\u27s involved in position location, early-late discriminator offset and cell sizes in conjunction with the varying number of users per cell on the accuracy of radiolocation estimation

Softswitch Design and Performance Analysis

The increasing number of subscribers’ demands in telecommunication sector has motivated the operators to provide high quality of service in cost effective way. Moreover, operators need to have an open structure system so that they can move their systems to the next generation network architecture. For this purpose, Softswitch is an appropriate technology because it is a safe and cost efficient solution and though it can migrate from traditional circuit-switching based telephone system to internet protocol packet-switching based networking. Softswitch network divides the logical switch into several parts with different functions such as signaling gateway, media gateway, media server, etc. Standard communication protocols are implemented between those parts. Softswitch is software-based system to make connection between devices, and moreover to control voice calls, data and routes calls through different entities of the networks. Softswitch supports management functions such as provisioning, fault handling and reporting, billing, operational support, etc. Softswitch suitable for all types of traffic and services so it is very demanding in the competitive world of mobile operators. In this thesis, Softswitch has been studied and analyzed in details. Softswitch network consisted of different integrated modules such as transportation, calling and signaling, service application and management. Each module provides different services such as call control, routing, billing and network management. Each module is discussed from functional and service point of views. Softswitch based wireless network architecture as well as variety of service solutions is presented. Different protocol interfaces in softswitch network such as signaling system number 7 are explained. Moreover, bearer calls, independent call control protocol, gateway control protocol, IP bearer control protocol are explained as well. Variety of softswitch network architectures analysis has been done based on their performance and the applicability. Three Softswitch network architectures are proposed which are validated through simulations.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format

Improving Quality of Vehicle Tracking Systems in Hill Stations Using IEEE 802.16 Networks

IEEE 802.16 standard was designed to support the vehicle tracking system applications with quality of service(QOS). Tracking system is used for tracking the vehicles in hill stations with quality of service(QOS). With the help of subscriber station(SS) can track the vehicles. Subscriber station’s will provide signals to the mobiles and vehicles .In this paper, we propose a scheme, named vehicle tracking system, to track the vehicles without any interrupt in hill stations with quality of service(QOS). The idea of the proposed scheme is to track the vehicles in the roads of the hill stations which is coming in opposite direction and back of the vehicle. Analysis and simulations are used to evaluate the proposed scheme. Simulation and analysis results confirm  that the proposed can track the vehicles with the help of subscriber station by given quality of service(QOS). Scheduling algorithms are proposed to improve the overall throughput. The simulation results show that our proposed algorithm improves the overall throughput by 40% in a steady network.DOI:http://dx.doi.org/10.11591/ijece.v3i1.213

Implementing an event-driven service-oriented architecture in TIP

Many mobile devices have a density of services, many of which are context or location-aware. To function, many of these services have to collaborate with other services, which may be located in many different places and networks. There is often more then on service suitable for the task at hand. To decide which service to use, quality of service measurements like the accuracy or reliability of a service need to be known. Users do not want third parties to have statistics on how and where they used services. Therefore the collaboration needs to be anonymous. This project implements a model of event-based context-aware service collaboration on a publish/subscribe basis. We compare different implementation designs, with focus on anonymity and quality of service of the services

Enhancing Cache Robustness in Named Data Networks

Information-centric networks (ICNs) are a category of network architectures that focus on content, rather than hosts, to more effectively support the needs of today’s users. One major feature of such networks is in-network storage, which is realized by the presence of content storage routers throughout the network. These content storage routers cache popular content object chunks close to the consumers who request them in order to reduce latency for those end users and to decrease overall network congestion. Because of their prominence, network storage devices such as content storage routers will undoubtedly be major targets for malicious users. Two primary goals of attackers are to increase cache pollution and decrease hit rate by legitimate users. This would effectively reduce or eliminate the advantages of having in-network storage. Therefore, it is crucial to defend against these types of attacks. In this thesis, we study a specific ICN architecture called Named Data Networking (NDN) and simulate several attack scenarios on different network topologies to ascertain the effectiveness of different cache replacement algorithms, such as LRU and LFU (specifically, LFU-DA.) We apply our new per-face popularity with dynamic aging (PFP-DA) scheme to the content storage routers in the network and measure both cache pollution percentages as well as hit rate experienced by legitimate consumers. The current solutions in the literature that relate to reducing the effects of cache pollution largely focus on detection of attacker behavior. Since this behavior is very unpredictable, it is not guaranteed that any detection mechanisms will work well if the attackers employ smart attacks. Furthermore, current solutions do not consider the effects of a particularly aggressive attack against any single or small set of faces (interfaces.) Therefore, we have developed three related algorithms, namely PFP, PFP-DA, and Parameterized PFP-DA. PFP ensures that interests that ingress over any given face do not overwhelm the calculated popularity of a content object chunk. PFP normalizes the ranks on all faces and uses the collective contributions of these faces to determine the overall popularity, which in turn determines what content stays in the cache and what is evicted. PFP-DA adds recency to the original PFP algorithm and ensures that content object chunks do not remain in the cache longer than their true, current popularity dictates. Finally, we explore PFP-β, a parameterized version of PFP-DA, in which a β parameter is provided that causes the popularity calculations to take on Zipf-like characteristics, which in turn reduces the numeric distance between top rated items, and lower rated items, favoring items with multi-face contribution over those with single-face contributions and those with contributions over very few faces. We explore how the PFP-based schemes can reduce impact of contributions over any given face or small number of faces on an NDN content storage router. This in turn, reduces the impact that even some of the most aggressive attackers can have when they overwhelm one or a few faces, by normalizing the contributions across all contributing faces for a given content object chunk. During attack scenarios, we conclude that PFP-DA performs better than both LRU and LFU-DA in terms of resisting the effects of cache pollution and maintaining strong hit rates. We also demonstrate that PFP-DA performs better even when no attacks are being leveraged against the content store. This opens the door for further research both within and outside of ICN-based architectures as a means to enhance security and overall performance.Ph.D.College of Engineering & Computer ScienceUniversity of Michigan-Dearbornhttps://deepblue.lib.umich.edu/bitstream/2027.42/145175/1/John Baugh Final Dissertation.pdfDescription of John Baugh Final Dissertation.pdf : Dissertatio