Kamil Kloch

Collaborative PDR Localisation with Mobile Phones

We investigate how an ad hoc collaboration between devices which happen to be physically close to each other can improve the quality of pedestrian dead-reckoning (PDR). The general idea is that whenever two users come close to each other, their devices use the proximity information to improve their PDR location estimates. In a public space the improvement will not only affect the two involved users, but also all the other people that they will meet and collaborate with in the future. On data collected from the mobile phones of 12 users over a course of three days during an open air festival in Malta (a total of 60 walked kilometres) we demonstrate that such collaboration can improve the localisation accuracy by a factor of four and prevent unbounded PDR error. The results imply that collaboration in crowded public spaces enables even simple smart phone-based PDR systems to provide effective localisation over long time periods and distances.

On-Line Chain Partitions of Orders: A Survey

AbstractOn-line chain partition is a two-player game between Spoiler and Algorithm. Spoiler presents, point by point, a partially ordered set. Algorithm assigns incoming points (immediately and irrevocably) to the chains which constitute a chain partition of the order. The value of the game for orders of width w is a minimum number val(w) such that Algorithm has a strategy using at most val(w) chains on orders of width at most w. There are many recent results about variants of the general on-line chain partition problem. With this survey we attempt to give an overview over the state of the art in this field. As particularly interesting aspects of the article we see: The sketch of the proof for the new sub-exponential upper bound of Bosek and Krawczyk:

Analytical and simulation models for collaborative localization

{\rm{val}}(w)\leqslant w^{16\lg(w)}

Scenario Based Modeling for Very Large Scale Simulations

.The new lower bound:

Sound-based proximity detection with mobile phones

{\rm{val}}(w)\geqslant(2-o(1))\binom{w+1}{2}

ON-LINE CHAIN PARTITIONS OF UP-GROWING SEMI-ORDERS

.The inclusion of some simplified proofs of previously published results.The comprehensive account on variants of the problem for interval orders.The new lower bound for 2-dimensional up-growing orders.

Emergent behaviour in collaborative indoor localisation: an example of self-organisation in ubiquitous sensing systems

Abstract Collaborative localization is a special case for knowledge fusion where information is exchanged in order to attain improved global and local knowledge. We propose analytical as well as agent based simulation models for pedestrian dead reckoning (PDR) systems in agents collaborating to improve their location estimate by exchanging subjective position information when two agents are detected close to each other. The basis of improvement is the fact that two agents are at approximately the same position when they meet, and this can be used to update local position information. In analytical models we find that the localization error remains asymptotically finite in infinite systems or when there is at least one immobile agent (i.e. an agent with a zero localization error) in the system. In the agent model we tested finite systems under realistic (that is, inexact) meeting conditions and tested localization errors as function of several parameters. We found that a large finite system comprising hundreds of users is capable of collaborative localization with an essentially constant error under various conditions. The presented models can be used for predicting the improvement in localization that can be achieved by a collaboration among several mobile computers. Besides, our results can be considered as first steps toward a more general collaborative (incremental) form of knowledge fusion.

On-Line Dimension of Semi-Orders

In order to develop complexity science based modeling, prediction and simulation methods for large scale socio-technical systems in an Ambient Intelligence (AmI) based smart environment, we propose a scenario based modeling approach. With a case study on AmI technology to support the evacuation from emergency scenarios, i.e. the Life Belt, a wearable computing systems for vibro-tactile directional guidance, we introduce the concept of model scaling from a micro to a macro level. Aligned with the scenario, we present how crowd simulation strategies encoded into a small scale simulation setup can be extended to a mixed-level simulation based on combining model aspects also coming from the large scale model. The experimental results of a real evacuation trail at a local railway station are incorporated to compare the evacuation efficiency for three strategies: (i) Potential Map, (ii) Evacuees familiarity of the exits and (iii) Exits usage optimization. A comparison with the earlier results from small scale simulation suggest that a real large scale simulation results may not be similar to that of small scale simulation due to dynamics of crowd built up and complexity of building structure.

On-line version of Rabinovitch theorem for proper intervals

We present a method for proximity detection with mobile phones that is based on a combination of Bluetooth communication (for the detection of coarse proximity) and sound beacons in an inaudible spectrum around 18kHz for a finer spatial resolution. The system performs a real-time recognition of personal encounters in two common situations: standing together and walking by each other. We evaluate our approach in a variety of settings ranging from office corridor, through a busy street to a shopping mall.

Ad-Hoc information spread between mobile devices: a case study in analytical modeling of controlled self-organization in IT systems

On-line chain partition is a two-player game between Spoiler and Algorithm. Spoiler presents a partially ordered set, point by point. Algorithm assigns incoming points (immediately and irrevocably) to the chains which constitute a chain partition of the order. The value of the game for orders of width w is a minimum number val(w) such that Algorithm has a strategy using at most val(w) chains on orders of width at most w. We analyze the chain partition game for up-growing semi-orders. Surprisingly, the golden ratio comes into play and the value of the game is