Department Publications

The paper presents the combined application of Geographical Information Systems (GIS), the Global Positioning System (GPS), the General Packet Radio Service (GPRS) and the Internet for tracking of vehicle fleets. It is one component of an enterprise solution that is designed to manage and track a large fleet. The key features of the system are an open-source GIS platform, real-time location information update, and a web-based user interface. The system consists of GPS-based vehicle tracking devices, a communications server, a web-server, a database server, and a map server. The tracking devices mounted in the vehicles collect location information in real-time via the GPS. This information is transferred continuously through GPRS to a central database. The users are able to view the current location of each of the vehicles in the fleet via a web-based application, and thereby manage the fleet. The vehicle positions and other related information are displayed on a digital map, which is made available by a map server. It is a typical example of how the advantages of ICTs may be leveraged for the efficient and effective management of a company's resources, particularly in the face of skyrocketing fuel costs.

The database correlation method (DCM) is a network based positioning technology which has shown superior in terms of accuracy. DCM is based on a pre-measured database of a location dependent variable such as received signal strength (RSS). Even though the technique has good potential, the practical difficulty in forming the database (fingerprints) using field measurements has become the major challenge in implementing this in large, dynamic networks. A remedy for this is to make use of propagation model predictions instead of field measurements to create the fingerprints. However, due to the considerable deviation between the predictions and the actual measurements, the positioning accuracy diminishes with this approach. In order to overcome this issue, tuning of the predictions using a small number of field measurements can be applied. The work presented in this paper proposes a technique for the correction of such deviations which would improve the performance of DCM. The proposed tuning process, Cell-wise Calibration, is based on artificial neural networks (ANN). Two different training algorithms, particle swarm optimization Algorithm (PSO) and BFGS Algorithm are applied for ANN training. The results of the trials carried out in urban, suburban and rural environments are presented. With the PSO algorithm, the level of accuracy is comparable to that obtained with a measured fingerprint database in urban and suburban environments, and is better in rural environment.

Churn is a measure of the number of subscribers who leave or switch to another carrier's service. The frequent migration of customers is in a way a threat to mobile operators as the expense on customer acquisition is greater than retention. On the other hand, for any operator it is difficult to maintain a steady growth in the market without maintaining the existing customers. Due to profound competition, controlling churn rate is becoming a challenge to Mobile Operators and identifying reasons for Churn is an even greater challenge as it is highly dependent on the values, culture, attitudes and perception of the different segments.

Abstract œ The paper describes the design and development of an emergency warning network that can disseminate disaster early warnings in three languages, to vulnerable communities over the GSM network. The Disaster Early Warning Network (DEWN) is a last-mile solution for early warning of disasters, and consists of a server at a warning dissemination centre, the GSM network and user terminals. The user terminals are mobile phones with the DEWN application and electronic alarm devices capable of generating audible, high-volume alarms and flashlights. The user devices generate alarms in response to a warning message from an authorized entity via GSM‘s short message service (SMS) or cell broadcast (CB). The design of DEWN follows international guidelines on emergency communications, such as the ability to reach a large number of people very fast, awaken sleeping communities, and be able to acknowledge warning messages.

The paper proposes an improved network-based positioning technique based on database correlation and presents the application of the proposed technique to GSM. The fingerprint database is created using field measurements and a novel and a more practical method for gathering fingerprints is introduced. The authors propose a Weighted k-Nearest Neighbor (WkNN) method for location estimation and the trial results obtained in urban and suburban environments in Sri Lanka are presented. Comparison with the Geometrical method shows that the proposed method is a competitive alternative for GSM location.

The paper describes the design and development of an emergency warning network that can disseminate disaster early warnings in three languages, to vulnerable communities over the GSM network. The Disaster Early Warning Network (DEWN) is a last-mile solution for early warning of disasters, and consists of a server at a warning dissemination centre, the GSM network and user terminals. The user terminals are mobile phones with the DEWN application and electronic alarm devices capable of generating audible, high-volume alarms and flashlights. The user devices generate alarms in response to a warning message from an authorized entity via GSM’s short message service (SMS) or cell broadcast (CB). The design of DEWN follows international guidelines on emergency communications, such as the ability to reach a large number of people very fast, awaken sleeping communities, and be able to acknowledge warning messages.

This paper illustrates two techniques for improved estimation of the location of Mobile Stations (MS) in cellular Networks. The first approach is the statistical method in which signal properties are treated as random variables which are statistically dependent on the location of the transmitter and the receiver. Location estimation for a set of observed signal strengths at a specific location is done as an inference problem. In the second approach, Database Correlation, signal information seen by an MS is stored in the form of fingerprints. To estimate the location, difference between the measurement and the database fingerprints is calculated using a correlation algorithm. Database fingerprints with least difference are selected as the nearest fingerprints for the location to be estimated. The two techniques have been tested through extensive measurements in two environments, urban and sub urban, to verify their …

The vision of this research paper is that the mobile phone is aware of its user's motion state and surroundings and modifies its behaviour especially the characteristics of Location-Based-Services based on this information. In the research it is implemented, and evaluated a methodology which can identify individual user, states. This learning is expected to occur online and not expected the requirement of any external supervision. The proposed system relies on hidden markov modelling and Log Likelihood Method. The implementation of the methodology is performed by first training the hidden markov model for the required number of states by an intended network trace. The log likelihood value of the data for each hidden markov model in the set is computed and the motion state is identified by choosing the hidden markov model that produced the highest value. The results of simulations carried out in WCDMA environment indicate that the proposed method is able to assist to create a meaningful user context model at various propagation conditions defined by both 3rd Generation Partnership Project (3GPP) and Wireless World Initiative New Radio (WINNER) propagation scenarios while only requiring a network trace without having an integrated sensor onboard cellular phone or any other wearable sensor device.

The paper describes the design and development of an alarm device that can disseminate disaster early warnings to threatened communities over the GSM network. The device is capable of generating audible, high-volume alarms, flashlights and turning on an in-built radio in response to a warning message from an authorized entity via GSM's short message service (SMS) or cell broadcast (CB). The design of the device follows international guidelines on emergency communications, such as the ability to reach a large number of people very fast, awaken sleeping communities, and be able to acknowledge warning messages. The alarm has been designed as a last-mile technology in a larger disaster early warning network (DEWN). It is intended to be place in selected locations such as police stations, places of religious places and community centres. Thus the DEWN system and thus the alarm device presents a …

Managing data related to Tsunami damage, and providing sufficient detailed information to interested parties in the reconstruction and recovery process is a challenge faced by the National Data Center, Sri Lanka. The paper proposes a Web-based GIS system to assist the post - Tsunami recovery process. The data components needed to provide timely information for decision makers were identified from the ambiguous subject domain of the massive-scaled disaster. It facilitates the user to access interactive maps and query information through the maps via a standard Web browser. All tools used are free and open source software which makes the system affordable to a developing country such as Sri Lanka. The Hambantota district was selected for a pilot-scale implementation of the proposed system.

The paper describes a system to automate the monitoring and recording of rainfall using cellular network infrastructure. The paper describes the hardware and the software components and the data communication aspects of the design, and their integration as a complete system. Ancient Sri Lanka had been proud for centuries, of a very successful agricultural economy. Today, even though Agriculture still plays a key role in the Sri Lankan Economy, the agricultural sector has failed to keep up with the adoption of advancing technology and has thus fallen behind many other developing nations. Weather information such as rainfall is critical for successful agricultural activities. Unfortunately present methods of monitoring such information utilize manual observation and recording of data which is highly error-prone. Automation of these monitoring methods can not only increase the reliability, but also improve the timely availability of data, and hence contribute significantly to the betterment of agriculture in day-to-day activities as well as to long-term planning. The system consists of rain gauges with wireless interfaces and a central station. The rainfall information is transferred via SMS (Short Message Service) messages to the central station via a GSM cellular network. The information is received in a database at the central station and can be accessed via the Internet, and the data analyzed.

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Telecommunications services in Sri Lanka were a total government monopoly until recently. Today, according to international estimates, it is one of the most deregulated telecom markets in Asia with regard to privatization and competition. Recent deregulatory measures, combined with several other social and economic factors have resulted in phenomenal advances in the telecommunications sector. However, the telecommunication revolution has been limited to urban areas, with the rural population being mostly left out. 78% of the telephone lines are concentrated in a few major urban areas, and the main line penetration stood at a mere 1.95% by the end of 1997.

New methods for generating additional capacity from the limited available spectrum for digital mobile, cellular and personal communications systems are introduced. Techniques for the improvement of spectral efficiency and capacity with modulation schemes currently in use are first investigated. The adoption of more spectrally efficient multilevel modulation formats to yield further improvements in capacity is then undertaken.

The spectral/power efficiency and performance of the pi /4-quadrature phase-shift keying (QPSK) modems (American and Japanese digital cellular emerging standards) are studied and briefly compared to GMSK modems (proposed for European Digital European Cordless Telephone System) (DECT) and Group Special Mobile System (GSM) cellular standards). Improved filtering strategies and digital pilot aided (digital channel sounding) techniques are considered for pi /4-QPSK and for other digital modems. More spectrally efficient modem trends and some research results for future cellular/mobile (land mobile) and satellite communication systems applications are also highlighted.<>

The Cellular Intercom enables users to make voice calls among themselves within a local area, using Bluetooth enabled mobile phones. It is an enterprise solution which enables people to use their mobile phones as a wireless intercom or PABX within their office premises. Conventional PABX or intercom systems provide terminals to the office desks of employees. If a person is not at his/her desk, he/she is unreachable. The Cellular Intercom is an attractive alternative for such environments, providing flexibility, ease of use and mobility within the office premises.

There is a growing call for the use of open source content standards for all-hazards, all-media alert and notification systems. This paper presents findings on the implementation of Common Alerting Protocol (CAP) as a content standard for a community-based hazard information network in Sri Lanka. CAP is being deployed as part of the HazInfo project, which has established last-mile networking capability for 32 tsunami-affected villages in Sri Lanka in order to study the suitability of various Information Communication Technologies (ICTs) for a standardsbased community hazard information system. Results to date suggest that the basic internetworking arrangement at lower technical layers has proven to be reasonably robust and reliable but that a key challenge remains in the upper layers of application software and content provision. This is evident in the apparent difficulties faced when implementing CAP messaging over multiple last-mile systems that include GSM Technology in modes of text messaging. Lessons learned from silent tests and live exercises point to several key bottlenecks in the system where the integrity of CAP messages is compromised due to problems associated with technological boundaries, technical difficulties, software interoperability or direct human intervention. The wider implication of this finding is that content standards by themselves are not sufficient to support appropriate and timely emergency response activities. Those working with content standards for hazard information systems must consider closely the interoperability issues at various layers of interconnectivity. It is also evident that before Cell Broadcasting …

This paper presents the results of work carried out to apply and evaluate the use of network planning tool predictions to the Database Correlation Method (DCM), for location estimation in cellular environments. In Database Correlation Method (DCM), the location dependent signal information seen by a mobile station is stored in a database in a form of fingerprints. During the location estimation, the measured signal sample is compared with the fingerprints stored in the database to come up with an accurate estimation. Even though the method has proven superior in accuracy over other cellular positioning techniques, the higher demanding effort involved in database formation using field measurements has become a big challenge which prevents the technique being deployed in large dynamic networks. Formation of a database using the predictions from the network planning tools or theoretical propagation models would be a possible solution for the issue. Then, the motivation arises to evaluate the accuracy of the method using predicted fingerprints instead of measured ones.