Yiming Ji

ARIADNE: a dynamic indoor signal map construction and localization system

Location determination of mobile users within a building has attracted much attention lately due to its many applications in mobile networking including network intrusion detection problems. However, it is challenging due to the complexities of the indoor radio propagation characteristics exacerbated by the mobility of the user. A common practice is to mechanically generate a table showing the radio signal strength at different known locations in the building. A mobile users location at an arbitrary point in the building is determined by measuring the signal strength at the location in question and determining the location by referring to the above table using a LMSE (least mean square error) criterion. Obviously, this is a very tedious and time consuming task. This paper proposes a novel and automated location determination method called ARIADNE. Using a two dimensional construction floor plan and only a single actual signal strength measurement, ARIADNE generates an estimated signal strength map comparable to those generated manually by actual measurements. Given the signal measurements for a mobile, a proposed clustering algorithm searches that signal strength map to determine the current mobiles location. The results from ARIADNE are comparable and may even be superior to those from existing localization schemes.

A survey and comparison on localisation algorithms for wireless ad hoc networks

In wireless ad hoc networks, nodes location information is useful for efficient routing and location-aware applications. This paper surveys this active area of research and presents a detailed comparison of most localisation algorithms in literature. Hardware requirements, reliability and accuracy are reviewed. The localisation methods are evaluated and compared under the same network settings.

Optimal Sniffers Deployment On Wireless Indoor Localization

Location determination of indoor mobile users is challenging due the complex and volatile indoor radio propagation signals. A radio-frequency (RF) based indoor localization system, like RADAR or ARIADNE, typically operates by first constructing a lookup table mapping the radio signal strength at different known locations in the building, and then a mobile users location at an arbitrary point in the building is determined by measuring the signal strength at the location in question and searching the corresponding location from the above lookup table. Usually, the mobiles signal strength is measured by three or more sniffers deployed inside the building. Obviously, the number of sniffers and their positions greatly affect the localization performance. This paper presents a detailed analysis and experimental results that explore the impact of the sniffers deployment on the performance of the indoor localization. The results demonstrate that the best localization performance is obtained when the center of gravity of the equilateral triangular (formed by three sniffers) coincides with that of the floor plan; and in order to provide optimal localization for all positions of a large floor, it is necessary to deploy more than three sniffers in a semi-mesh style such that any position in the building is always covered by three nearby sniffers.

Impact of Building Environment on the Performance of Dynamic Indoor Localization

Location determination of mobile users within a building is challenging due to the complexities of the indoor radio propagation characteristics. For a RF based indoor system, a common practice is to construct a signal strength map table showing the radio signal strength at different known locations in the building. A mobile users location at an arbitrary point in the building is then determined by measuring the signal strength at the location in question and determining the location by referring to the above map table using a LMSE (least mean square error) criterion. Much work has been done lately in the indoor radio propagation in order to automatically generate the signal strength map table according to the changing environment. This research is based on the ARIADNE indoor localization system with the purpose to analyze the impact of building structures and indoor furniture on the performance of the indoor localization. We provide a simple strategy to model these indoor structures, and we verify the methodology using a complex basement building. Experimental results indicate that up to 15% improvement in location estimation is achievable from the proposed method

Impact of sniffer deployment on indoor localization

The demand for location based applications including network intrusion detection has grown tremendously lately. However, location determination of indoor mobile users is challenging because of the complexities of the indoor radio propagation characteristics. A radio-frequency (RF) based indoor localization system, like ARIADNE, typically operates by first constructing a lookup table mapping the radio signal strength at different known locations in the building, and then a mobile users location at an arbitrary point in the building is determined by measuring the signal strength at the location in question and searching the corresponding location from the above lookup table. Usually, the mobile users signal strength is measured by three or more sniffers mechanically deployed inside the building. Obviously, the sniffers position configuration and the number of available sniffers greatly affect the localization performance. This paper presents experimental results that explore the impact of the sniffers deployment on the localization based on the ARIADNE system. The results demonstrate that the triangular deployment and extra available sniffers generally generate better localization performance

Dynamic indoor localization using wireless ethernet: the ARIADNE system

Location determination of mobile users within a building has attracted much attention lately due to its many applications in mobile networking including network intrusion detection problems. However, it is challenging due to the complexities of the indoor radio propagation characteristics exacerbated by the mobility of the user. A common practice is to mechanically generate a table showing the radio signal strength at different known locations in the building. A mobile users location at an arbitrary point in the building is determined by measuring the signal strength at the location in question and determining the location by referring to the above table using a LMSE (least mean square error) criterion. Obviously, this is a very tedious and time consuming task. This paper proposes a novel and automated location determination method called ARIADNE. Using a two dimensional construction floor plan and only a single actual signal strength measurement, ARIADNE generates an estimated signal strength map comparable to those generated manually by actual measurements. Given the signal measurements for a mobile, a proposed clustering algorithm searches that signal strength map to determine the current mobiles location. The results from ARIADNE are comparable and may even be superior to those from existing localization schemes.

An interference-aware routing metric in multi-radio multi-hop networks

It is generally admitted that the performance of ad hoc networks can be quite poor and disappointing due to high contention and lack of an optimal MAC protocol. Here we investigate one approach to alleviate the contention: allowing nodes to communicate simultaneously on different channels by configuring them with multiple radios. Though simply adding radios improves throughput, a more dramatic enhancement can be obtained when using an interferenceaware routing metric, which improves the TCP throughput by an average of 89% against single radio network.

A glance at MAC protocols for ultra wideband

Ultra wideband (UWB) technology offers unique advantages for wireless communications: precise location-timing capabilities, imperceptibility, low power, low complexity, and low cost. No existing wireless network successfully takes advantage of the properties of this technology because of the lack of an efficient medium access control (MAC) technology. In this brief, we overview the strengths of UWB and take a glance at research on MAC protocols for UWB. UWB is a promising technology suitable for cross-layer optimizations from physical layer to network layer. Precise location, arrival of angle, and directional antennas may well open the door to an optimal usage of the spectrum and highly energyefficient routing schemes.

Interactive software architecture design with modeling & simulation

Due to the increasing complexity of real world problems, it is costly and difficult to evaluate todays software-intensive systems. This paper explores component interaction pattern, and provides a set of methodologies for specifying, verifying, and validating (by simulation) system temporal behavior, with the aim of validating software design iteratively at design and development time. The methods combine such components and technologies as UML, XMI, database, model checking, and simulation.

BaseStation assisted TCP: a simple way to improve wireless TCP

In recent years, extensive research effort has been devoted to TCP congestion control in hybrid wired-wireless networks. A general agreement is that the TCP sender should respond differently to wireless losses and disconnection, i.e., not slow down as drastically as for congestion losses. Thus, research focus for wireless TCP congestion control is the discrimination between the wireless inherent packet losses and the network congestion packet losses in wired network. In addition, researchers attempt to detect temporary or lengthy wireless disconnection. This paper proposes a simple but novel strategy, dubbed BSA-TCP (Base Station Assisted TCP), (1) to accurately discriminate wireless losses from wired network congestion losses and (2) to detect and notify a TCP sender about wireless disconnections. The key distinctive feature of the proposed scheme is its general use for most issues at stake for TCP over wireless: loss discrimination, wireless disconnection and handoffs. It also circumvents the asymmetric problem that acknowledgements might follow different paths from those of data packets. Such asymmetry problem is common to mechanisms that buffer and retransmit wireless lost data packets locally at the base station. The proposed method also addresses energy efficiency