Projects at Aalborg University

I have a masters degree in Communications Systems (cand. polyt.) from Aalborg University. Class of 2009.

This is a collection of the projects I participated in during my education (2004-2009). Titles and abstracts are written in the original language of the project (Dansih or English).

Udgangspunktet for dette projekt er at øve gruppearbejde og herved nå et resultat i form af en fælles rapport.

Formålet med projektet er at undersøge de effektværdier som højttalerproducenter angiver på deres produkter.

Forbrugerne er i vildrede, da forskellige effektangivelser benyttes på højttalersæt. For at dokumentere omfanget af denne problemstilling er foretaget en mindre spørgeskemaundersøgelse blandt de studerende på Den Teknisk-Naturvidenskabelige Basisuddannelse på Aalborg Universitet.

For teknisk at belyse problemet, er et højttalersæt med en imponerende effektangivelse blevet indkøbt. Det vil blive undersøgt, om det er muligt at få højttalersættet til at levere de 360 watt, som producenten angiver på emballagen.

Denne rapport omhandler overordnet prioritering af forskellige former for trafik på Internettet. Indgangsvinklen er online gruppearbejde, og altså prioriteringen af de applikationer der bruges til dette.

Vi har undersøgt om studerende i dag har behov for at kunne være mere i kontakt med gruppen når der arbejdes hjemmefra end det er muligt i dag. Lige ledes har vi undersøgt hvilke muligheder der er for at realisere ideen.

For at undersøge hvilke praktiske muligheder der er for at prioritere mellem de applikationer online gruppearbejde kræver samtidig, har vi lavet en forsøgs-opstilling som skal simulere Internettet.

Forsøget har vist at der er behov for prioritering hvis realtidsapplikationer skal kunne afvikles problemfrit. Dette er gøres på portnummer, men det er ikke en brugbar løsning. ToS og MPLS ville være en bedre løsning.

Formålet med dette projekt er, at undersøge mulighederne for at forbedre de nuværende brugervejledninger ved hjælp af programmer til visualisering og simulering af produktets funktioner.

Vi har gennem en problemanalyse undersøgt, hvilke forbedringer elektroniske brugervejledninger til en mobiltelefon giver i forhold til traditionelle, og hvordan disse formidles bedst muligt. Derudover har vi lavet en mindre spørgeskemaundersøgelse for, at undersøge brugerens synspunkter på og behov for den elektroniske brugervejledning. På baggrund af problemanalysen har vi fundet ud af, at der er potentiale i at udvikle en elektronisk brugervejledning som supplement til de traditionelle vejledninger. Det skyldes at der kan bruges flere modaliteter til formidling, og derfor er det muligt at nå flere dele af en målgruppe end ellers.

Vi har i løsningsforslaget søgt, at udvikle en elektronisk brugervejledning, der kan hjælpe med forståelsen af brugen af mobiltelefoner, og samtidig virke som salgsmateriale. Vi har anvendt SPU's V-model til udvikling af et sådant program, hvor vi anvender teorierne om formidling og læring. Produktet af dette projekt er en elektroniske brugervejledning som er udformet som en Java Applet, hvilket gør at brugervejledningen er let tilgængelig og samtidig velegnet til salgsmateriale.

Rapporten beskriver udviklingen og implementeringen af et styresystem til en lagerrobot. Styresystemet er udviklet til microprocessoren MSP430F149. For at teste systemet bygges en lagerrobot, af LEGO Mindstorms styret af mikroprocessoren. Derudover defineres et testlager, hvor robotten navigerer rundt ved hjælp af streger på gulvet. Forbindelsen til robotten er en standard RS232 seriel forbindelse over bluetooth. Robottens formål er at kunne flytte pallerne rundt på forskellige pladser på lageret, hvor der er ikke taget højde for eventuelle forhindringer. Udover automatisk navigation, er det desuden muligt at kontrollere robotten manuelt. Til dette er der lavet en brugerflade i GTK, der muliggør denne styring, samt tilføje og fjerne automatiske opgaver. Kravspecifikationen bliver opfyldt på de de fleste punkter, hvilket kan bekræftes ved accepttesten.

The purpose of this project has been to develop a new way to send SMS-messages by making unanswered phone calls which makes it possible to send the messages for free.

Different methods could be used to accomplish this and the most robust method with groups of phones calling each other was selected. By letting the phones from the sender group make calls in a specific pattern it is possible to derive different bit combination.

An application using this method has been developed for Nokia Series 60 phones. The application has been implemented using Python for Series 60 with extension modules in Symbian C++.

The application has been tested on Nokia 6600 and N70 and can successfully send a message of 20 character from one group of phones to another in 65% of the attemts. With the current implementation the avarage time of sending one character is 94 seconds with each group containing 2 members.

This project covers the analysis and design of a Mission Control Client for the Global Educational Network for Satellite Operations (GENSO) project, a project managed by the International Space Education Board (ISEB).The main purpose of the GENSO project is to widen the communication window with student satellites. This is done by allowing remote control of ground stations connected in a network, The network interface application is called a Mission Control Client (MCC)

Initial requirements for the GENSO project, did not fulll requirements for a sufficient requirement specication. Therefore work was done to restructure and reformulate these. The final requirement specication is still missing important parts regarding functionality, because the GENSO project is still in the requirement iteration phase. Most of this project report documents the first design iteration from the requirement specification. The conclusion states that the design is ready to implement prototype code, but more iterations are needed before implementation can begin.

Wireless sensor networks consist of spatially distributed autonomous small devices, often called „motes“, which cooperatively monitor, collect and exchange data from the surrounding environment.

Aalborg University has developed a mote which integrates a Bluetooth module and a low cost Industrial, Scientic and Medical (ISM) band module which makes possible to establish a multi-hop connection between the motes.

The purpose of this project is to design and implement a Medium Access Control (MAC) protocol for the ISM module of the mote platform, proving a solution to avoid collisions between packets during transmission. A collision avoidance scheme with acknowledgements and carrier sensing has been designed and implemented to minimize data loss and duplication. This is also known as Request-To-Send (RTS) / Clear-To-Send (CTS) medium reservation mechanism.

To test the implementation of this protocol, a mobile phone application is developed which allows a user to exchange text, image and audio files through the mote network. The acceptance test concludes that the implementation is robust and works as stated in the requirements specification except for one requirement regarding maximum transmission range. This is however due to the antenna calibration and is not software related.

Wireless sensor networks are expected to be widely used in communication and control systems in the future. Some applications introduce only partially connected sensor networks leading to lower reliability or availability of the measured data. The objective of this project is to develop and analyze a data distribution method which can increase the system reliability and keep the memory consumption low on each device.

A Reed-Solomon coding scheme is applied as a solution where a certain number of unavailable devices can be tolerated without jeopardizing the system reliability. A probabilistic system model is derived to describe the distribution and reconstruction of a message from a sensor to the gateway. This model is verified and visualized by means of a simulation implemented in Java. A prototype of a system containing two data devices and one redundant device is implemented to test the model in a real life scenario. Performance evaluation shows that the probability to receive all sensor measurements by using the proposed cooperative data distribution method is higher compared with the non-cooperative case.

Reliable data retrieval from a sensor network can require a temporal distributed data storage of the measured data among all motes. This is the case when a source of information, or a gateway, is only occasionally present in the network. We consider a network consisting of motes that in order to save energy independently of each other go into offline mode, switching their radios off. We propose a cooperative mechanism for data distribution that increases system reliability, and at the same time keeps the memory consumption for data storage low on each device. A Reed-Solomon coding scheme is applied as a solution where a certain number of unavailable devices can be tolerated without jeopardizing the system reliability. A prototype of a system is implemented to test the protocol behavior under realistic conditions. Prototyping is done on the OpenSensor platform developed at Aalborg University. To observe the system performance in different settings, additionally a simulator is developed. Performance results indicate that the proposed cooperative data distribution method outperforms the non-cooperative one. The metric used to estimate the system reliability is the probability to retrieve all sensor measurements.

The aim of this project is to investigate how to do indoor positioning based on Bluetooth. This is done by outlining different possible scenarios and the actions needed to obtain the position of a Mobile Device. A prototype system is designed to track a Mobile Device in a room in two dimensions by measuring Received Signal Strenght at three Base Stations. Two different methods are tested on the obtained measurements: A simple trilateration based on measurements from all three Base Stations without any history of the position, and a particle filter implementing a mobility model of the user.

The methods are compared and it is concluded that the measurements are too noisy to obtain a clear trend using trilateration. The Particle Filter using the Less Drunk model performs better and is able to produce a track with a trend similar to the correct path.

It is concluded that Bluetooth with use of Received Signal Strenght measurements is not an optimal technology for indoor positioning, but it gives good estimation.

In this project we investigate three different CSMA/CA based MAC protocols in terms of saturated throughput, channel access delay and energy consumption. The considered protocols are: Basic CSMA/CA, Packet Aggregation and Cooperative MAC. The investigation is based on analytical models and measurements obtained from an implementation of the three protocols. While the basic CSMA/CA approach is alike IEEE 802.11, the other two approaches are based on aggregation of packets per node and a clustered approach. It is shown that both Packet Aggregation and Cooperative MAC increases the throughput compared to the basic CSMA/CA approach, but only Cooperative MAC results in lower channel access delay. The energy consumption of Packet Aggregation and Cooperative MAC is very similar, but lower than the basic CSMA/CA.

In this paper we investigate three different MAC protocols based on CSMA/CA in terms of throughput and channel access delay. The investigation is based on analytical models and real implementations on a testbed developed for this purpose. While the first MAC approach is alike IEEE802.11, the other two approaches are based on Packet Aggregation per node and on cooperative approaches. It can be shown that the two novel MAC schemes are increasing the throughput compared to the standard CSMA/CA approach, but only the cooperative approach is resulting in lower channel access delays.