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  • 101.
    Jilani, Umer Naeem
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Siddiqui, Tauseef Ahmed
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Tariq, Umar
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Analysis on Fixed and Mobile WiMAX2007Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    WiMAX which represents World Interoperability for Microwave Access is a major part of broadband wireless network having IEEE 802.16 standard provides innovative fixed as well as mobile platform for broadband internet access anywhere in anytime. This thesis provides the detail about the two main applications of WiMAX which are fixed WiMAX and Mobile WiMAX. Fixed WiMAX 802.16 delivers point to multipoint broadband wireless access to our homes and offices. Whereas Mobile WiMAX gives full mobility of cellular networks at higher broadband speeds than other broadband networks like Wi-Fi. Both applications of WiMAX are designed in a proper network planning which is helpful to offer better throughput broadband wireless connectivity at a much lower cost.

  • 102. Johnson, Henric
    Lightweight Authentication for Bluetooth2004Conference paper (Refereed)
    Abstract [en]

    Authentication of Bluetooth devices on a per-packet basis is a challenging research problem since it is a low power technology with limited computational resources and storage capacity. In this paper, we describe a lightweight per-packet authentication protocol well suited for Bluetooth's constrained environment. The proposed authentication protocol is presented with one bit for authentication but could with facility be extended to $k$ bits for a higher security level. Since packets might be lost due to a bad wireless channel or an attack, the protocol needs to be robust and not lose synchronization of the authentication bits. A detailed description of a synchronization algorithm is presented and evaluated via simulation and analysis.

  • 103. Johnson, Henric
    Lightweight Authentication in Wireless Networks2004Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, we develop and analyse two novel authentication protocols well suited for wireless devices. iven that wireless devices have limited resources such as processing power, bandwidth, storage, and energy, the proposed authentication protocols need to be lightweight. Due to these limitations there is a tradeoff between security and performance. To guarantee complete network access control the authentication is performed on a per-packet basis. Therefore, a Lightweight Authentication Code (LAC) is embedded in each packet as an authenticator. Authentication is necessary to guarantee the identity of a source since, with a wireless network, an adversary could easily inject traffic to get access to a network or launch a Denial-of-Service attack. The protocols are designed to be generic and applicable to standards such as IEEE 802.11 and Bluetooth. In order to handle packet loss or an attack, synchronization algorithms are advanced and analysed to synchronize the sender's and the receiver's LACs. We further propose to use the lightweight authentication protocol as part of a detection and response scheme to handle Denial-of-Service attacks such as resource exhaustion. Five Adaptive Packet Discard Mechanisms (APDMs) are presented, in which the lightweight authentication protocols function as a first line of defense to protect the second and much stronger security service from exhaustion. With these mechanisms, we believe it is possible to reduce, if not remove, the effects of a Denial-of-Service attack on complex security systems. Finally, we extend the applicability to secure usage-based accounting, in which lightweight authentication per-packet is necessary to utilize accounting resources efficiently and guarantee accounting correctness.

  • 104. Johnson, Henric
    Toward Adjustable Lightweight Authentication for Network Access Control2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The increasing use of Internet access networks raises the demand for secure and reliable communication for both users and businesses. Traditionally, the aim has been to provide the strongest possible security. However, with the demand for low-power computing it has become desirable to develop security mechanisms which efficiently utilize available resources. The tradeoff between performance and security plays an important role. In general, strong security is added even if there is no attack. The implementation of strong and resource demanding security often implies more than a secure system; it may deteriorate the performance of a device with limited resources and pave the way for new threats such as resource exhaustion. It is, therefore, unwise to use strong cryptographic algorithms for devices with limited resources in the absence of an adversary. It is more efficient to begin with lightweight security, taking further measures when an attack is detected. The overall focus of this thesis is on adjustable and lightweight authentication protocols for network access control. The thesis studies the performance degradation of strong security using empirical tests on IP security (IPSec) with a visual bottleneck indicator based on the time-discrete fluid flow model and throughput histogram differences. The results emphasize the possibility of a Denial of Service (DoS) attack against IPSec itself. The redundant authentication performed in a Wireless Local Area Network (WLAN) also motivates the development and evaluation of novel lightweight authentication protocols for the link and network layer. The developed authentication protocols are resource efficient, per-packet based, and robust in terms of handling packet loss. The protocols are further used as part of a hierarchical defense structure, which has been implemented and evaluated in order to mitigate protocol based DoS attacks. Finally, this thesis presents the concept of Always Best Security (ABS) and a practical decision making model based on the Analytic Hierarchy Process. The model takes a number of factors into consideration, including subjective and objective aspects of security in order to select an adequate authentication level. It is a flexible model which formalizes quantitative and qualitative considerations of a defined set of criteria, keeping Quality of Service in mind.

  • 105. Johnson, Henric
    et al.
    Isaksson, Lennart
    Fiedler, Markus
    Wu, Felix
    A Decision System for Adequate Authentication2006Conference paper (Refereed)
    Abstract [en]

    A practical decision system is developed for finding the adequate authentication level based on desirable security criteria and alternatives. Even though the notion of lightweight security is acknowledged, the process of determining when to use it instead of strong security is not well understood. The process of making such a decision can be very complex. By defining an overall security goal and a set of criteria with corresponding alternatives, the Analytic Hierarchy Process (AHP) is used to select the most suitable, preferred (and thus, adequate) authentication level, which is demonstrated by a realistic case study.

  • 106.
    Johnson, Henric
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Nilsson, Arne A.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Detection and Response Policies Using a Hierarchical Scheme2004Conference paper (Refereed)
    Abstract [en]

    To protect and secure critical wireless network communications, high-end security services are used to encrypt, authenticate and validate packets. This approach opens up a new area of system attacks. Since the security services are time and resource demanding, a service may be easily overworked. Using Adaptive Packet Discard Mechanisms in conjunction with a lightweight packet classifying mechanism, it is possible to reduce, if not remove, the effects of a Denial-of-Service attack on complex security services, and thus creating a hier-archical approach to security.

  • 107. Johnson, Henric
    et al.
    Qaisrani, Babar
    Fiedler, Markus
    Wu, Felix
    Nilsson, Arne A.
    Analysis of IPSec Performance2005Conference paper (Refereed)
    Abstract [en]

    In this paper we present the results of an experimental analysis of IPSec performance. IPSec serves as a security service to protect a communication session over unreliable networks using several cryptographic functions. The different IPSec features used to obtain confidentiality, authentication, replay protection, and integrity introduce performance costs brought about by the increased processing overhead. The performance parameters of interest are delay and throughput. However, there is a tradeoff between performance and security. The results of the performance tests indicate the vulnerability of a Denial-of-Service attack against a gateway running IPSec due to resource exhaustion.

  • 108. Johnson, Henric
    et al.
    Qaisrani, Babar
    Fiedler, Markus
    Wu, Felix
    Nilsson, Arne A.
    Hierarchical Defense Structure for Mitigating DoS Attacks2006Conference paper (Refereed)
    Abstract [en]

    This paper provides the contribution of mitigating a Denial-of-Service (DoS) attack via a developed hierarchical defense structure with proactive functionality. An important aspect is the tradeoff between performance and security. This novel hierarchical architecture is presented with lightweight authentication protocols acting as a classifier to deny access to harmful traffic. An empirical test of the proposed structure has been performed and results are reported which display the capability of the structure to filter and separate the attack traffic before reaching the target of an IPSec gateway. Thus, the filtering of traffic is performed without being the target itself for new resource exhaustion attacks. The considered IPSec environment is based on IPSec gateways for the low-end market, i.e., for small businesses or private networks.

  • 109.
    Karlberg, Magnus
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Keycaller: Mobila tjänster inom telematik med ett telefonstyrt motorlås2004Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [en]

    This is a thesis report concerning mobile services within telematics for a telephone controlled motor lock. This report constitutes a pre-study on how to develop this from an idea to a fully operational product. The basic idea is to make it possible to control a lock no matter where you are in the world. This thesis is made in association with the company Creab/Trossö Lås in Karlskrona, Sweden and I would like to take the opportunity to thank all those that in some way have been involved in this project. First I would like to thank Tommy Romlin and Ola Corneliusson at Creab/Trossö Lås for their patience with the project. I would also like to thank my first examiner Ulrick Rodin as well as my new examiner Gunnar Råhlén for their support in this. A special thanks to my family for their support during this thesis.

  • 110.
    Kautto, Toni
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Söderberg, Torbjörn
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Implementation of a Short Message Service Centre in a TCP/IP environment2003Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    Developing Short Message Service (SMS) and Enhanced Message Service (EMS)services require advanced and complex testing to assure the reliability, durability and credibility of the services. Such tests include various error scenarios within the Global System of Mobile communications (GSM) networks, i.e. packet loss and bit errors. In any arbitrary GSM networks such errors rarely appear and are almost impossible to repeat, which makes test results quite unreliable. This master thesis presents a simulation of a Short Message Service Centre (SMSC). A SMSC is the part of a GSM network that handles the messaging, e.g. SMS and EMS transmissions. By placing the SMSC in a Transport Control Protocol/Internet Protocol (TCP/IP) environment both money and time are saved, through the reliability and speed of modern Local Area Networks (LAN). The implementation of the SMSC Simulator (SMSCS) proved to be very satisfying. It was very well received by the developers, as an eagerly awaited complement for the SMS and EMS service development. Almost any kind of error scenario can be generated through the simulator, since it allows both data manipulation and traffic generation.

  • 111.
    KHAN, ABID-AZIZ
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    LATIF, MUHAMMAD-AMIR
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    QUALITY OF SERVICE DURING VERTICAL HANDOVER IN 3G/4G WIRELESS NETWORKS2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Handover means transferring an on going call or data sessions one cell to another. Handovers occur due to the movement of the mobile user from one area to another area. Handovers are used to prevent an on going call to be disconnected. If we don’t use handovers then whenever a user leaves the area of a particular cell then its on going call is immediately disconnected. The process of handovers requires a number of parameters e.g. what is the handover scheme we are using, how many channels are free. In the handover process we should also keep the QoS up to the standard. Vertical handover may be referred to a process of transferring call connected to a network/data session from one channel connected in a cell to the core network of another. A suitably equipped device may be able to use both technologies at a time, the high speed Wireless LAN and cellular technology. Wireless LAN connections generally provide higher bandwidth but smaller coverage area as compared cellular networks which have lower bandwidth and wide coverage. Thus the user can use a Wireless LAN connection whenever it’s available, while when it isn’t available can switch to a cellular connection as an alternative. Vertical handover refers to automatic switching the communication/data session from one technology to the other. So, it’s different from a horizontal handover among various wireless access points using the same technology. In this thesis we’ll try to find out reason behind the quality degradation during vertical handover and try to suggest improvements to maintain a minimum standard of quality during handover.

  • 112.
    Khan, Mubbashar Altaf
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Ahmad, Sohaib
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Decision Making Techniques for Cognitive Radios2008Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    Spectrum scarcity is one of the biggest challenges that the modern world is facing. The efficient use of available licensed spectrum is becoming more and more critical with increasing demand and usage of the radio spectrum. Different researches show that the usage is not uniform throughout the licensed spectrum rather it is heavy in certain parts of the spectrum and has portions that are utilized inefficiently. Some researchers even claim that more than 70% of the licensed frequency band is not in use, most of the time. So, there is much room for work yet in the unutilized parts or the inefficiently utilized parts of the spectrum, to overcome the spectrum scarcity problem. Different researches are in progress and ways are being found to efficiently utilize the available licensed spectrum. One of the ways is the use of “Cognitive Radio”, according to this; the already licensed spectrum can be used more efficiently by introducing artificial intelligence, the decision-making to be specific, in the radio. This enables the radio to learn from its environment, considering certain parameters. Based on this knowledge the radio can actively exploit the possible empty frequencies in the licensed band of the spectrum that can then be assigned to other processes in such a way that they don’t cause any interference to the frequency band that is already in use. This makes the efficient usage of the available licensed spectrum possible. The users that are allocated the licensed frequency bands of the spectrum are the primary users and the users that are allocated the empty frequencies within the licensed frequency band, according to their requested QoS specifications, are known as the secondary users or the cognitive users. They are called as the secondary users as they utilize the unused spectrum resources only, on non-interfering basis, with the primary users. This thesis will focus on the implementation of different spectrum allocation techniques for these secondary users, based on Genetic Algorithms and an evaluation of the performance of these techniques using Matlab coding. This research will focus on the decision-making process mainly, with an assumption that the radio environment has already been sensed and the QoS requirements for the application have been specified either by the sensed radio environment or by the secondary user itself.

  • 113.
    Khan, Waqas Ahmad
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Impact of DRX on VoIP Performance and Battery Life in LTE2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Along with higher data rates and application-enriched user terminals, LTE has even higher requirements to conserve the battery power in mobile devices compared to the WCDMA terminals. In LTE, Discontinuous Reception (DRX) has been introduced as one of the key solutions to conserve battery power in mobile terminal. It is very meaningful to investigate the possible impact of DRX on power consumption and also the VoIP performance. This study evaluates several different parameter settings for DRX, and tries to find a reasonable trade-off between VoIP performance and battery life. This study report proposes DRX parameter setting to achieve maximum possible power saving with minimum VoIP degradation. Based on the assumed power saving model and simulation scenario presented in chapter 4 and chapter 5 of this report respectively, the proposed parameter settings can achieve up to ~60% of the terminal power saving. Furthermore, it is concluded that longer DRX cycles are not suitable for VoIP traffic since they introduces longer delays and degrades the VoIP performance particularly in downlink.

  • 114.
    Kim, Ngan Trieu
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Ajiboye, Olumide
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    PERFORMANCE ANALYSIS OF ADAPTIVE ARRAY SYSTEM AND SPACE-TIME BLOCK CODING IN MOBILE WIMAX (802.16e) SYSTEMS2008Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    We live in an information hungry age, we generate and process information at a rate never before recorded in the history of mankind. Today’s computing platforms are run on Gigahertz multi-core processors churning out Gigabits streams of data that need to be transmitted as quickly as possible. Often times the source and the destination are mobile which means wired connections are not a choice. This has led to an ever increasing need to develop wireless access technologies that support high throughput regardless of the transmission environment. Till date, many proprietary solutions exist that seek to bridge this gap with little or no support for interoperability. For the sheer scale of development that is required, a standard based solution is the key. The IEEE 802.1x committee oversees the development of standards for wireless systems, it formed the 802.16 working group to develop a standards-based Wireless Metropolitan Area Network (MAN) solution. One of the fruits of this effort is the 802.16e standard fondly referred to as mobile WiMAX and it is the subject of study in this thesis. This thesis seeks to analyze the transmission characteristics of two of the antenna systems defined in the standard i.e. Adaptive Beamforming Systems and Multiple-Input Multiple-Output Systems. Multiple-Input Multiple-Output (MIMO): utilizes multiple antennas at the transmitter and receiver to provide diversity gain, multiplexing gain or both. Adaptive Antenna Systems (AAS): Adaptive array system uses an antenna array to generate in real-time radiation patterns with the main lobes and/or nulls dynamically tuned to specific directions in order to increase or suppress signal power in that direction.

  • 115.
    Mahesar, Fayaz Ahmed
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Dynamic Channel Allocation in GSM Network2008Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    The rapid evolution of cellular technology and the more user demand for advanced mobile services leads the industry to develop more efficient network structures. The increasing number of cellular subscribers and the demand for cellular networks communication (3rd and 4th generation) drives to the research of the new methodologies for the design of cellular networks and services. This thesis has been generated and complied with the objective of proposing GSM Network Utilizing DYNAMIC CHANNEL ALLOCATION starting with the architecture of GSM Network with system design. In next chapter we define the channels that are transmitted over the Air Interface, leading further towards the Channel Allocation Schemes in GSM. In this chapter we describe the various types of channels are used in GSM Network. Furthermore define the main two strategies for channel assignment, briefly differentiate between the FCA (Fixed Channel Allocation) and (Dynamic Channel Allocation) as well as advantages of both schemes. Then the major is study of (Dynamic Channel Allocation) and the proposed Algorithm for Dynamic Channel Allocation in GSM network is presented and discussed. All channels will placed in a pool and on demand or on request will be assigned to the user for that particular call that will be helpful to maintain the grade of service and increase system capacity.

  • 116.
    Mama, Mounchili
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Short Range Wireless Network Integration in Intelligent Environments2007Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    The advent of low powered battery computing devices such as laptops, personal digital assistants (PDAs), faced up new challenge when it come to sharing information and available resources. We need to adopt a more reliable and efficient or cost effective approach to interconnect them together in order to make various services access possible. The idea of wired connectivity is to be discarded since do not fit with the cost policy and not self organizing as generally requires human intervention. Therefore considering the reliability aspect, the breakthrough for such application, is to design a short range wireless network that will enable automatic connectivity and immediately share data among them. In many circumstances, short-range wireless networks like Bluetooth serves as a prototype environment for demonstrating ad-hoc network access in intelligent environments. If we believe all of the hype surrounding Bluetooth technology, we can expect our fridge to use our mobile phone to order groceries over the Internet, and, of course, end up ordering an extremely expensive new car instead of a steak. The ability to access such services heavily depend on the platform providing integrated and discovered services. Bluetooth devices must register as platform services that need to be available as Bluetooth services. In both environments, system integration must be performed and additional communication link must be established. The goal of the work is to enable access services on an integrated non-Bluetooth intelligent system via Bluetooth enabled device (Client-Server architecture), vice versa. Finally the design and implementation of a prototype application supporting short-range wireless network is implemented in embedded Java APIs for Bluetooth Wireless.

  • 117.
    Mehari, Tariku Temesgen
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Frequency Hopping in LTE Uplink2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    In the 3GPP LTE, different radio resource management (RRM) techniques have been proposed in order to improve the uplink performance. Frequency hopping is one of the techniques that can be used to improve the uplink performance by providing frequency diversity and interference averaging. The hopping can be between subframes (inter-subframe) or within a subframe (intra-subframe). 3GPP specifies two types of frequency hopping for the LTE uplink, hopping based on explicit hopping information in the scheduling grant and sub-band based hopping according to cell-specific hopping and mirroring patterns. In this master’s thesis, theoretical discussion on the frequency hopping schemes is carried out followed by dynamic simulations in order to evaluate the performance gain of frequency hopping. Based on the theoretical analysis, the second type of hopping is selected for detailed study. As a baseline for comparison, dynamic frequency domain scheduling with random frequency resource allocation has been used. Single cell and multi-cell scenarios have been simulated with VoIP traffic model using user satisfaction as a performance metric. The simulation results show that frequency hopping improves the uplink performance by providing frequency diversity in the single cell scenario and both frequency diversity and interference averaging in the multi-cell scenario. The gains in using the hopping schemes were reflected as VoIP capacity (the number of satisfied users) improvement. In this study, the performance of the selected hopping schemes under different hopping parameters is also evaluated.

  • 118.
    Mughal, Muhammad Irfan Younas
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Khan, Mustafa
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    A Study Report on Content Distribution Network’s Technology & Financial Market2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    With the advancement of the Internet age, the need for more and more data distribution to different users on different types of networks in short time and at a nominal cost has also increased significantly. To achieve these objectives several technologies have been used with different sorts of implementations but only few survive in today’s very competitive financial market. The objective of our thesis is to study the technology and the financial market of the Content Distribution Network, which has up till now proven to be a very good and effective way to meet the always increasing demands of the rapidly developing Internet age. In this thesis, we will not only discuss the taxonomies of the Content Distribution Network or CDN, its different types and implementations but we will also focus on its financial issues and its performance in the financial market. The aim of our project is to study and understand the technology of the CDN, the problems related to its implementations, research work and its money matters.

  • 119.
    Muhammad, Bilal
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Closed loop power control for LTE uplink2008Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    This thesis study involves designing, implementing and testing of a novel radio resource control algorithm for the closed loop power control in the LTE uplink. Different values of the path loss compensation factor are investigated in the range 0.7-1.0 and an optimal value of 0.8 as allowed by the LTE standard is proposed. Both the ideal and a more realistic case modeled by including delay, error, and power headroom reporting were studied. Simulation results indicated that the closed loop power control with fractional path loss compensation factor is advantageous compared to closed loop power control with full path loss compensation. Using a simple upload traffic model, the closed loop power control with fractional path loss compensation factor improved the system performance in terms of mean bit rate by 68% in the ideal case and 63% in the realistic case. The power headroom report triggering at change in path loss gave better performance than triggering at periodic intervals.

  • 120.
    Mwanza, Jason
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Nyirenda, Bained
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Performance Evaluation of Routing Protocols in Mobile Ad hoc Networks (MANETs)2008Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    The IETF MANET working group mandate was to standardise IP routing protocols in MANETs. The RFC 2501 specifies the charter for the working group. The RFCs still has unanswered questions concerning either implementation or deployment of the protocols. Nevertheless, the working group identifies the proposed algorithms as a trial technology. Aggressive research in this area has continued since then, with prominent studies on routing protocols such as AODV, DSR, TORA and OLSR. Several studies have been done on the performance evaluation of routing protocols using different evaluation methods. Different methods and simulation environments give different results and consequently, there is need to broaden the spectrum to account for effects not taken into consideration in a particular environment. In this project, we evaluate the performance of AODV, OLSR, DSR and TORA ad hoc routing protocols in OPNET. We simulate a Mobile ad hoc network with all nodes in the network receiving FTP traffic from a common source (FTP server). In this way, the results of this analysis would also represent a situation where the MANET receives traffic from another network via a common gateway. In addition, the mobile nodes were randomly placed in the network to provide the possibility of multihop routes from a node to the server. The performance of these routing protocols is evaluated with respect to routing overhead, throughput, end-to-end delay and packet delivery ratio. In this study, results show that OLSR floods the network with the highest amount of routing traffic followed by TORA, AODV and DSR. All the protocols exhibit a low packet delivery ratio of maximum 59%. This degradation is expected due to huge retransmissions in the network because of using TCP traffic. OLSR outperforms AODV, DSR and TORA in terms of end-to-end delay and throughput. Varying traffic volumes or speeds in the network, leaves OLSR superior in terms of end-to-end delay and throughput. OLSR build and maintains consistent paths resulting in low delay. The results in this study also confirm TORA’s inability to handle rapid increases in traffic volumes. TORA performs well in networks where the volume of traffic increases gradually.

  • 121.
    Mynampati, Vittal Reddy
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Kandula, Dilip
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Garimilla, Raghuram
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Srinivas, Kalyan
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Performance and Security of Wireless Mesh Networks2009Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    The thesis aims to find issues that may affect the performance of meshed wireless networks. There is no denying the fact that out of the wireless technologies being used in today’s environment, the wireless meshed technology is one of the most advanced and can be viewed as the technology of the future. This thesis deals closely with aspects like throughput, security and performance as these metrics have a direct influence on the performance of the wireless mesh.The thesis is subdivided into various categories explaining the primary structure of wireless mesh networks. Performance of the network has always been a key issue and reliability is the core metric of evaluating the quality of a network. Routing protocols for these networks and which help in improving the performance are examined and the best routing protocol is suggested. This helps to improve the throughput which is the main aspect for maintaining a good performance. The main problem with wireless networks is making them security. This area is also considered as it improves the performance of the whole network. Also the network should be scalable to properly utilize the frequency and get optimal performance. This is required for the successful delivery of data packets. Thus, this area is also investigated together with some other factors that influence the behaviour of these networks. Last, but not least, we provide a discussion about possible future work as well as specifying a system that will help to increase the performance.

  • 122.
    Nawaz, Omer
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems. Blekinge Inst Technol, Dept Commun Syst, Karlskrona, Sweden..
    Minhas, Tahir Nawaz
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems. Blekinge Inst Technol, Dept Commun Syst, Karlskrona, Sweden..
    Fiedler, Markus
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems. Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems. Blekinge Institute of Technology, School of Computing. Blekinge Inst Technol, Dept Commun Syst, Karlskrona, Sweden..
    Optimal MTU for Realtime Video Broadcast with Packet Loss - A QoE Perspective2014In: 2014 9TH INTERNATIONAL CONFERENCE FOR INTERNET TECHNOLOGY AND SECURED TRANSACTIONS (ICITST), IEEE , 2014, p. 396-401Conference paper (Refereed)
    Abstract [en]

    Multimedia applications have become the prime source of Internet traffic in recent years due to high bandwidth offered by almost all access mechanisms. This highlights the need of intense research efforts to improve the already demanding user perception levels for high-performance video delivery networks. Quality of Experience (QoE) based metrics are often used to quantify user satisfaction levels regarding an application or service. In this paper, we have analyzed the impact of variable frame sizes at link layer with different packet loss scenarios to evaluate the performance degradation of H.264 based live video streams from the end user perspective using subjective tests. We have focused on both subjective and objective quantitative measures to analyze the myth that smaller packets provide better quality in error-prone networks. We found that this assumption may not be true for some cases with a considerable packet loss ratio. Moreover, we observed that full-reference video assessment software like PEVQ predicts QoE to an acceptable extent, which allows cutting cost and effort coming with subjective evaluations. Keywords-Quality of Experience, Multimedia communication, Streaming media

  • 123.
    Nwabude, Arinze
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Wireless Local Area Network (WLAN): Security Risk Assessment and Countermeasures2008Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Wireless LANs popularity has been on the rise since the ratification of the IEEE 802.11b standard in 1999. In recent years, wireless LANs are widely deployed in places such as business organizations, government bodies, hospitals, schools and even home environment. Mobility, flexibility, scalability, cost-effectiveness and rapid deployment are some of the factors driving the proliferation of this technology. However, the architecture of this technology made it insecure as WLANs broadcast radio-frequency (RF) data for the client stations to hear. This presents new challenges for network administrators and information security administrators. This study was undertaken to find out if wireless networks are inherently insecure thereby limiting enterprise deployment. If yes, what are the known holes, and can they be fixed? The security mechanisms of wireless LANs were not within the scope of this work. The author tried to answer these questions through comprehensive and broad literature study. The study shows that wireless LANs are prone to many different kinds of attacks – ranging from passive to active, and that wireless security initiative has come a long way, from weak WEP to a more robust WPA2. It also show that optimal security solution for Wireless LANs involves a combination of security technologies, and that vulnerability assessment and risk analysis are essential for development of effective security policy and determination of appropriate security measures for risk mitigation.

  • 124.
    Nwup, Emineimo Kennedy
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Akande, Adesola Idris
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Evaluation of the pre IEEE 802.11s RFC: Aspects of the Design and Implementation of the Mesh Station with RA-OLSR in the C-Core2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    The demand for ubiquitous networks has pushed the designs of networks all the way. The requirement for access point to be integrated into IEEE 802.3 standard and other networks has always been a sore point in the limitation of wireless coverage of IEEE 802.11 standard networks. Wireless Mesh Network (WMN) is expected to be the future of the next generation wireless network. It is experiencing a fast growing development due to its attractive features which includes high reliable connectivity, easy deployment, self healing, self configuring, flexible network expansion etc. Hence the mobility of the WMN nodes has been of paramount importance, which would make it independent of wired infrastructure and flexible interoperability with various networks and devices. The requirements like mobility, transparency etc. have led to the amendment of the WMN standard by the Institute of Electronics and Electrical Engineering (IEEE) 802.11 Working Group (WG), Task Group (TG) “S. The IEEE 802.11s standard tackles these issues by its operation on layer 2 of Open Systems Interconnection (OSI) reference model and creates a transparent IEEE 802 broadcast domain that supports any higher layer protocol. In our work we give the evaluation of the upcoming IEEE 802.11s standard based on its features some of which include routing at layer 2 and medium access control to enable its design and implementation in the existing mesh frame work of Communication Research Labs (CRL) using the proposed IEEE 802.11s routing protocols with focus on RA-OLSR and HWMP. We concentrate on how to integrate these features into the existing CRL’s C-CORE which runs other layer 3 routing protocols and complex functions as Application Programming Interface (API) modules. The implementation of the IEEE 802.11s standard creates major challenges as we have to create a roadmap on integrating the new wireless kernel interfaces like the nl80211, cfg80211 and the Wireless Extension (Wext) into the CRL’s C-CORE framework for communication between user space and kernel space, especially taking into consideration of the existing HAL and madwifi wireless drivers of the CRL’s framework. To support the evaluation of the features like the layer 2 routing and the modified MAC performance, we compare results of the CRL’s real time mesh network test with our simulation result of the IEEE 802.11s standard using the Qualnet 4.5 simulator with focus on the basic network parameters like delay, jitter and throughput. The comparison shows that the CRL’s network has higher throughput running its existing layer 3 protocols. The analysis also proves that the 802.11s is flexible, scalable and efficient in delivering multi hop capabilities to clients that cannot afford the deployment time or the cost for wired networks that use access points. With the complete integration, of the 802.11s standard specifications the CRL’s C-CORE framework can be much more capable of supporting more diverse network scenario deployments.

  • 125.
    Obiekwe, Obinna
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Optimizing Application Traffic on MPLS-Enabled Network Links.2008Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    The expectations of every user of today’s internet is becoming relatively high more especially as the internet applications are becoming steadily sensitive to time and delays. The critical nature of some of these applications is more apparent now that they are real-time. These pose a whole lot of challenges to network operators and service providers because they will not only need to provide these services to users but also ensure that these services rendered meet up to quality expectations and standards. It is therefore very necessary and important for them to provide good quality of service with appreciable good performance at no incurable costs- that is while maximizing revenue- to them. A need therefore arises for the adoption of a scalable method or tool for meeting up to these challenges. Multi-Protocol Label Switching (MPLS) stands out to be the choicest tool and key for providing these requirements because of its traffic engineering (TE) capability in IP network and as such the internet needs to be equipped with this all-embracing technology. This report presents the performance analysis of this technology (MPLS TE) vis-à-vis the traditional IP with respect to the average throughput, Quality of service rendered, delay suffered and minimization of congestions or traffic overflow in a bid to seeing how and why MPLS is more capable in optimizing traffic applications when adopted by service providers and network operators. And from the conclusion of the analysis and results it would have been established that MPLS appeared to be more capable in the optimization of traffic applications with respect to the above characteristics when compared with the traditional IP.

  • 126.
    OLADIPO, ANDREW AYOOLA OLUSEYI
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Stratospheric Propagation And HAPs Channel Modeling2007Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    High Altitude Platform Stations (HAPs) are communication facilities situated at an altitude of 20 to 50 km and at a specified, nominal, fixed point relative to the Earth. They are mostly solar-powered, unmanned, and remotely-operated. These platforms have the capability of carrying multipurpose communications relay payload, which could be in the form of full base station or, in some cases, a simple transponder as is being used in satellite communication systems. Services and applications that will be provided and supported by HAPs include; future generation mobile telephony, broadband wireless access, navigation and positioning systems, remote-sensing and weather observation/monitoring systems, etc. HAPs are billed to be the next big thing in providing infrastructure for wireless communications and there are several ongoing and exciting research works into various aspects of this emergent technology. Expectedly, the need to predict the channel quality and analyze the performance evaluation of such stratospheric propagation has generated quite a few models. This thesis work provides some insight into this new aspect of wireless communications in terms of the need for a new system, its benefits, challenges services provided and applications supported. Finally, 4 channel models developed for the HAPs environment are reviewed and one that has been found, upon analysis, to be broad-based and rather realistic in its results is implemented in order to evaluate the system performance using the bit error rate (BER).

  • 127.
    OLAYINKA, ABDULAZEEZ
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    ADENUGA, KEHINDE
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    SECURITY FOR BROADBAND METROPOLITAN AND WIDE AREA NETWORK AT THE ACCESS INTERFACE LEVEL2007Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    These thesis report deals with a range of secure high-speed networking over a metropolitan or wide area. Since this is quite active research area, a full report is given of the interfaces that thrive in removing the bandwidth burden from long distance networks. Only those with the status or potential of a standard are taking into consideration. Next, the position of security is evaluated. It is recommended that the access Interface enjoys certain advantages over the upper layers. Hence, the results of this work are directly applicable to virtually any layered communication architecture. Amongst the security protocols that are available, the IEEE802.11 represents the only viable solution to have the CLS service properly secured. This protocol is designed for a different type of environment and the implications of this are known. In the real sense, IEEE802.11 proves to be a very valuable tool to built multi-level secure private and public networks using the most recent MAN/WAN technologies. Furthermore, it shows how to enhance the security issues related to Metropolitan and Wide Area Network considering the required security services and mechanism.

  • 128.
    Onoabhagbe, Solomon
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Zigbee versus Radio Frequency Identification (RFID)2008Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    The growth of Telecommunication in the world has brought about the need for regular update, research and findings, to meet the demands of the global world. With the rising demand of home automation and sensor network, the ZigBee protocol has been identified to target on low power devices, Personal Area Network (PAN) and sensor nodes. Wireless wearable systems crave room for new user interface components. This fosters the ease of mobility and availability of devices, in order to accomplish things when necessary. Since the technology of the global world is fast changing, it therefore brings about a very high level of competition and challenges among developers, programmers, systems engineers, telecommunication engineers and a host of others. When people fail to measure up to the present day demand, their design and market structure tends to drop. Wireless systems are gradually phasing out wired systems due to the ease of operation and usage. Also, with the existence of wireless systems, there tend to be the need to invest as little as possible and then having an operation that can be maximally effective and reliable. This research work talks about the ZigBee versus RFID technology and how they are correlated. Zigbee is solely targeted at Radio Frequency Identification (RFID) applications, requiring a low data and battery life and also a secure network. At a technical level, it is more reliable, supports larger networks and is more fully featured. However, a very good comparison is made between ZigBee and RFID. The choice therefore of a company, individual or organization is determined by their utmost priorities in line with some factors like performance output, implementation cost, security, usability and profit marginalization.

  • 129.
    Onuzulike, Vincent
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    ROUTING FOR QoS IN AD HOC WIRELESS NETWORKS2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    ABSTRACT Ad hoc network is a collection of wireless mobile nodes which dynamically form a temporary network without the use of any pre-existing network infrastructure or centralized administration. They operate by interactions among their neighbourhood wireless mobile nodes. Such interactions provide the required administration and control functions that support networks of that nature. Ad hoc wireless networks provide significant advantages on wide environments and certain applications. These types of networks could be internally fault-resilient, since they do not work under fixed topology. However, the networks are time-varying since all the nodes operate as mobile. Ad hoc networks automatically adapt to environments which are at the extremes of high mobility with low bandwidth and vice versa. In an ad hoc network that is multi-hop and for two nodes that are not direct neighbours, the communication between these nodes require that there should be a relay of message by the node that is in between them. Each of these nodes in the network acts as a router and also as a communication end-point. The cooperation and collaboration of all network layers is required for the provision of QoS support. Growth in wireless communication has been very astronomical in the past few years. Every technology is going wireless. Quality of service is a big issue that has to be addressed. Our main concern here is QoS routing. Every node broadcasts beacon packets periodically identifying it and its QoS characteristics. In the centre of ad hoc networking lies beaconing mechanism because without this, a node will not know its adjacent neighbours that changes dynamically in an ad hoc networking scenario. For routing, the knowledge of adjacent neighbours is very essential. To support QoS for real time traffic we need to know not only the minimum delay path to destination, but also the bandwidth available on it. We would also deal with how to improve QoS in an ad hoc wireless network; and Universal Mobile Telecommunications Systems (UMTS). QoS in an ad hoc wireless network pose a complex issue because of dynamic nature of the network topology; but, it would be addressed here.

  • 130.
    Osagie, Solomon Ighodalo
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Ighagbon, Oziegbe
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    IP Routing for Next Generation Network Services2007Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    As the market for high speed Internet and cellular communication services reaches maturity, communication services have shown a limit to growth based on the number of subscribers. Next Generation Networks services based on IP Routing form the beginning of a new age of innovative and affordable services where consumers will witness substantial new service offerings and also savings in their consumption bills for such services. The requirement of these applications challenges the limitations of the network technologies that are in place today. Next Generation Networks are based on internet technologies including Internet Protocol (IP) and Multi-protocol Label Switching (MPLS). The thesis therefore presents an overview of the converged IP Network services, focusing on opportunities for service differentiation and introducing current service oriented technology to meet up the demands of consumers. These technologies allow service providers to build and operate networks that can be able to provide local, long distance, global, mobile, data, voice and internet services to consumers. In meeting the demands of these newer services to its customers adequately with high Quality of Service (QoS), Speed, Traffic Engineering and Scalability, Internet Service Providers have engaged Next Generation Networks using the more reliable Multi-Protocol Label Switching in the core of their networks while also delivering such services through a secure means over the public internet by using Virtual Private Networks.

  • 131.
    Pjanic, Dino
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Jönsson, Tomas
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Ad Hoc Routing for Bluetooth2005Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    The number of Bluetooth equipped devices has increased tremendously over the last couple of years and many new products using Bluetooth are expected to be launched on the market. Bluetooth is a low cost, low power, short range radio technology, developed as a cable replacement to connect devices such as cellular phones, headsets, Personal Digital Assistants (PDA's) and so on. Bluetooth is a part of the Wireless Personal Area Network (WPAN). In a WPAN the members may be constantly changing as devices move in and out of range. A basic formation of a Bluetooth network is called a piconet, consisting of maximum eight devices, where one of the devices acts as master unit. The Bluetooth specification defines a method for the interconnection of piconets: the scatternet. A scatternet can be dynamically constructed in an ad hoc manner when some nodes belong, at the same time, to more than one piconet. The current Bluetooth specification only defines the notation of a scatternet but does not provide the mechanism to construct the scatternet. In order to make Bluetooth more suitable and efficient in an ad hoc environment routing algorithms are needed. However, routing algorithms are not defined in Bluetooth specification. The time-to-connect is essential when creating an ad hoc network. An implementation of the Modified Reverse Path Forwarding (MRPF) routing algorithm based on the original Reverse Path Forwarding (RPF) routing algorithm is evaluated. Empirical data are extracted and compared to the original. The results show that MRPF uses less number of connections and decreases the time-to-connect compared to the RPF algorithm.

  • 132.
    Popescu, Adrian
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Cognitive Radio Networks2012Conference paper (Other academic)
    Abstract [en]

    Cognitive Radio Networks (CRNs) are emerging as a solution to increase the spectrum utilization by using unused or less used spectrum in radio environments. The basic idea is to allow unlicensed users access to licensed spectrum, under the condition that the interference perceived by the licensed users is minimal. New communication and networking technologies need to be developed, to allow the use of the spectrum in a more efficient way and to increase the spectrum utilization. This means that a number of technical challenges must be solved for this technique to get acceptance. The most important issues are regarding Dynamic Spectrum Access (DSA), architectural issues (with focus on network reconfigurability), deployment of smaller cells and security.

  • 133.
    Popescu, Adrian
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Routing on Overlay Networks: Developments and Challenges2005In: IEEE Communications Magazine, ISSN 0163-6804, Vol. 43, no 8Article in journal (Refereed)
    Abstract [en]

    Overlay networks are networks operating on the inter-domain level, where the edge hosts learn of each other and, based on knowledge of underlying network performance, they form loosely coupled neighboring relationships. These relationships can be used to induce a specific graph, where nodes are representing hosts and edges are representing neighboring relationships. Graph abstraction and the associated graph theory can be further used to formulate routing algorithms on overlay networks. The main advantage of overlay networks is that they offer the possibility to augment the IP routing as well as the QoS functionality offered by the Internet.

  • 134.
    Popescu, Adrian
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Constantinescu, Doru
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Measurement of One-Way Transit Time in IP Routers2005Other (Other academic)
    Abstract [en]

    The main goals of the tutorial are towards an understanding of the delay process in best-effort Internet for both non-congested and congested networks. A novel measurement system is reported for delay measurements in IP routers, which follows specifications of the IETF RFC 2679. The system is using both passive measurements and active probing and offers the possibility to measure and analyze different delay components of a router, e.g., packet processing delay, packet transmission time and queueing delay at the output link. Dedicated application-layer software is used to generate UDP traffic with TCP-like characteristics. Pareto traffic models are used to generate self-similar traffic in the link. The reported results are in form of several important statistics regarding processing and queueing delays of a router, router delay for a single data flow, router delay for more data flows as well as end-to-end delay for a chain of routers. We confirm results reported earlier about the fact that the delay in IP routers is generally influenced by traffic characteristics, link conditions and, at some extent, details in hardware implementation and different IOS releases. The delay in IP routers may also occasionally show extreme values, which are due to improper functioning of the routers. Furthermore, new results have been obtained that indicate that the delay in IP routers shows heavy-tailed characteristics, which can be well modeled with the help of three distributions, either in the form of single distribution or as a mixture of two distributions. There are several components contributing to the One-Way Transit Time (OWTT) in routers, i.e., processing delay, queueing delay and service time. Our results have shown that, e.g., the processing delay in a router can be modeled with the Normal or skewed Normal distribution, and the queueing delay is well modeled with a mixture of Normal distribution for the body probability mass and of Weibull distribution for the tail probability mass. It has been also observed that One-Way Transit Time (OWTT) is well modeled with the generalized Pareto distribution. Furthermore, OWTT has several component delays and it has been observed that the component delay distribution that is most dominant and heavy-tailed has a decisive influence on OWTT. To the best of our knowledge, this is the first time we understand the distributional properties of the delay process in an IP router.

  • 135. Popescu, Adrian
    et al.
    Erman, David
    Ilie, Dragos
    Popescu, Alexandru
    Fiedler, Markus
    Vogeleer, Karel De
    Seamless Roaming: Developments and Challenges2008Conference paper (Other academic)
    Abstract [en]

    The paper reports on recent developments and challenges focused on seamless handover. These are subject for the research projects MOBICOME and PERIMETER, recently granted by the EU EUREKA and EU STREP FP7, respectively. The research projects are considering the recently advanced IP Multimedia Subsystem (IMS), which is a set of technology standards put forth by the Internet Engineering Task Force (IETF) and two Third Generation Partnership Project groups, namely 3GPP and 3GPP2. The foundation of seamless handover is provided by several components, the most important ones being the handover, mobility management, connectivity management and Internet mobility. The paper provides an intensive analysis of these components.

  • 136. Popescu, Adrian
    et al.
    Fiedler, Markus
    Kouvatsos, Demetres
    Content Distribution over IP: Developments and Challenges2006Conference paper (Refereed)
    Abstract [en]

    This is an invited tutorial on "Content Distribution over IP: Developments and Challenges", with special focus on overlay routing

  • 137. Popescu, Alexandru
    et al.
    Erman, David
    Fiedler, Markus
    Kouvatsos, Demetres
    Routing in Content Addressable Networks: Algorithms and Performance2009Conference paper (Refereed)
    Abstract [en]

    Over the last years, virtual networking has evolved towards becoming a dominant platform for the deployment of new services and applications such as large-scale data sharing, multimedia services, application-level multicast communication. A consequence of this evolution is that features like robust routing, efficient search, scalability, decentralization, fault tolerance, trust and authentication have become of paramount importance. Since network virtualization basically represents the process of combining resources of different types, two distinct aspects stand out. The first aspect is virtualization of hardware on network entities, while the second being in essence a virtualized network such as an overlay network. In this context, overlay networks act as enablers by providing the addressing and routing substrates needed to implement a virtualized network structure. In this paper, we focus on the second aspect of network virtualization and consider the specific case of structured overlay networks with a particular focus on Content Addressable Networks (CAN). An investigation of the existing approaches for structured P2P overlay networks is provided, where we point out their advantages and drawbacks. The essentials of CAN architecture are presented and based on that, we report on the implementation of a CAN simulator. Our initial goal is to use the simulator for investigating the performance of the CAN with focus on the routing algorithm. Preliminary results obtained in our experiments are reported as well. The results indicate that greedy routing algorithms perform better than non-greedy algorithms.

  • 138. Popescu, Alexandru
    et al.
    Ilie, Dragos
    Kouvatsos, Demetres
    On the Implementation of a Content-Addressable Network2008Conference paper (Refereed)
    Abstract [en]

    Over the last years, the Internet has evolved towards becoming the dominant platform for deployment of new services and applications such as real time and multimedia services, application-level multicast communication and large-scale data sharing. A consequence of this evolution is that features like robust routing, efficient search, scalability, decentralization, fault tolerance, trust and authentication have become of paramount importance. We consider in our paper the specific case of structured peer-to-peer (P2P) overlay networks with a particular focus on Content-Addressable Networks (CANs). An investigation of the existing approaches for structured P2P overlay networks is provided, where we point out their advantages and drawbacks. The essentials of CAN architecture are presented and based on that, we report on the implementation of a CAN simulator. Our initial goal is to use the simulator for investigating the performance of the CAN with focus on the routing algorithm. Preliminary results obtained in our experiments are reported as well.

  • 139.
    Qaisar, Naeem
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Ahmad, Mushtaq
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Challenges and Solution of UMTS Handover2008Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    ABSTRACT Universal Mobile Telecommunications System (UMTS) is the third-generation (3G) cell phone technology. UMTS offers telecommunications services (like speech or SMS) and bearer services, which provide the capability for information transfer between access points. It is possible to negotiate and renegotiate the characteristics of a bearer service at session or connection establishment and during ongoing session or connection. Both connection-oriented and connectionless services are offered for Point-to-Point and Point-to-Multipoint communication. The radio interface of UMTS is called UTRAN (UMTS Terrestrial Radio Access Network) which uses W-CDMA as the underlying air interface [19]. 4G technology is also being developed for the heterogeneous networks e.g. WiMax. Today mobile wireless infrastructure is commonly-seen as one of the most advanced form of human communications. The last decade GSM technology has been a leading force in this revolution. Simultaneously with the phenomenal deployment of wireless networks and distribution of user terminals, also the Internet has seen a similar revolutionary growth. Handover means changing/switching of a mobile transmission from one channel to another. The main purpose of handover is to maintain an ongoing call when the hardware changes the channel, whether it is in the same cell or a different cell. Whenever a handover occurs there is always a handover delay which dictates that we cannot guarantee the service continuity. Though the handover time is msec but if there is a long handover latency, it will results in high packet losses and degradation of end-to-end TCP performance in case of packet switched data. Delay sensitive real-time applications demands packet lossless and low latency Quality-of-Service (QOS) guarantee during handover. In this thesis we will find the reasons of delay and packet loss during the handover and effect on the QOS (quality of services).

  • 140.
    Rahim, Shafqat
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Evalution of VOD by using MPLS network.2009Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    My project aims to develop the solution in iptv for Video-on-Demand to provide users with a world of choices - for more channels to view along with the ability to enjoy what they want, when they want, according to their desires and time constraints. This contribution briefly proposes areas that need familiarity and implementation of network technology that brings forward the requirements of the bearer network for the IPTV service VOD.

  • 141.
    Rehman, Sheikh Riaz Ur
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Investigation of different VPN Solutions2009Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    Abstract The rapid growth of e-business in past few years has improved companies efficiency and revenue growth. E-business applications such as e-commerce, remote access has enabled companies to manage processes, lower operating costs and increased customer satisfaction. Also the need rises for the scalable networks that accommodate voice, video, and data traffic. With the increased dependability of networks the security issues are raised and networks become more and more vulnerable to different types of security threats. To overcome security issues different security technologies are in action by vendors and technologists. Also for the survival of many businesses to allow open access to network resources, today’s networks are designed with the requirement of availability to the Internet and public networks, therefore, information confidentiality is the major issue in these networks to ensure that the network resources and user data are as secure as possible. With the requirement of network security, concept of Virtual private network was established. A Virtual Private Network (VPN) can be defined as a network in which connectivity between multiple customers’ sites is deployed on a shared network with the same security as a private network. Different VPN technologies and protocols architectures are available in market among are MPLS VPN architecture, IPSec VPN architecture, and SSL VPN architecture. Like With the introduction of Multiprotocol Label Switching (MPLS), which combines the benefits of Layer 2 switching and Layer 3 routing, it became possible to construct a technology that combines the benefits of an overlay VPN with the benefits of peer-to-peer VPN implementation in which routing is simple. MPLS/VPN is a new and simple technology, which provides simpler to routing and also makes number of topologies easy to implement which are otherwise difficult to implement. All architectures have benefits and drawbacks, also each of them can be implemented separately or in combination of other according to customer security requirement and performance of the network.

  • 142.
    Rubin, Andreas
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    IF Trions hemsida2005Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [sv]

    Detta är rapporten för hur IF Trions hemsida kom till och utvecklades. Från det att iden kläcktes tills det att hemsidan var helt färdigställd. Arbetet bygger mycket på de olika säkerhetsbrister som en hemsida kan ha, till exempel hur lösenord ska hanteras. Med avseende på detta så ingår ett avsnitt i rapporten om de vanligaste säkerhetsproblem som man kan tänkas stöta på under uppbyggnadsfasen och exempel på hur man kan lösa dem. PHP är det programmeringsspråk som IF Trions hemsida är kodat med. För att göra det lättare att välja vilket programmeringsspråk man ska använda sig av när man ska börja koda en hemsida så ingår ett kapitel som tar upp fördelar och nackdelar om PHP och ASP. Detta är de två ledande programmeringsspråken för producering av hemsidor.

  • 143.
    Sackey, Eric
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Performance Evaluation of M-ary Frequency Shift Keying Radio Modems via Measurements and Simulations2006Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    M-ary Frequency Shift Keying is a power efficient modulation scheme that is currently used by manufacturers of low power low data rate data transmission equipment. The power efficiency of this modulation increases as the signal alphabet increases at the expense of increased complexity and reduced bandwidth efficiency. There is, however, a gap between the performance of real world systems employing Frequency Shift Keying (FSK) and that of theoretical FSK systems. To investigate the nature of this gap, a comparison is needed between the performance of real world systems using FSK and that of theoretical FSK systems. This thesis investigates the nature of this gap by simulating 2, 4 and 8-level FSK systems in additive white Gaussian noise channel using MATLAB, measuring of the performance of commercially available data transmission equipment manufactured by RACOM s.r.o of the Czech Republic, and comparison of their performances. Some important results have been illustrated and also, it is observed that the gap between the performance of theoretical and real world systems using FSK is about 1 dB at a bit error rate (BER) of 10-3 and widens as BER decreases.

  • 144.
    Saleem, Muhammad Kamran
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Electrostatic Forces for Swarm Navigation and Reconfiguration2007Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    In this study, we have developed a navigation scheme for a swarm of satellites equipped with both electrostatic and conventional actuators. The main features of two new concepts for formation flying control i.e. electrostatic actuation, used for active control of spacecraft charging for relative position control and equilibrium shaping, which is a behavior based swarm navigation technique are highlighted in this study. The work described in this report is divided into two main sections. In the first section, the propulsion system is investigated. The GEO region is selected for this study since, the Debye length is sufficiently high in this region and a model of the interaction between plasma and a charged spacecraft is derived. On the basis of this result the requirements for the hybrid propulsion system are defined and a new charge control strategy with two currents i.e. charging and stabilizing current is proposed. The stabilizing current Ist counteracts the natural environmental currents and drive the spacecraft potential toward zero and charging current is emitted with the acceleration voltage of desired potential level and drives the spacecraft to desired potential level in certain range. The candidate propulsion system consists of a radio frequency ion thruster engine (RIT) and an electron gun for emission of charges from the spacecraft. In the second phase of the study the applicability of the electrostatic actuation for formation keeping and reconfiguration of swarms of satellites is considered. The recently developed equilibrium shaping navigation technique has been selected to control the maneuvers of the swarm. There is a specified set of formations that can be acquired in an autonomous way by means of the ES technique and a specified set of formation can be maintained only relying upon the EA concept. The compatible formations are those that can be acquired autonomously relying upon the ES path planning scheme and maintained using only the EA. These formations enjoy both a high level of autonomy, ensured by the equilibrium shaping, and high fuel efficiency, provided by the electrostatic actuation. Exploiting the results on the compatibility, the electrostatic interaction between the SC has been considered to increase the efficiency of acquisition or reconfiguration maneuvers. In particular it has been demonstrated that the electrostatic force can be used to reduce the fuel expenditure of the whole swarm.

  • 145.
    Salih, Sami H O
    et al.
    Sudan University of Science and Technology, SDN.
    Erman, Maria
    Blekinge Institute of Technology, Faculty of Engineering, Department of Applied Signal Processing.
    Mohammed, Abbas
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    A Novel Spectrum Sensing Scheduling Algorithm for Cognitive Radio Networks2012In: Self-Organization and Green Applications in Cognitive Radio Networks / [ed] Al-Dulaimi, Anwer; Cosmas, John; Mohammed, Abbas, IGI Global , 2012, p. 136-153Chapter in book (Other academic)
  • 146.
    Sandberg, Daniel
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Automatiserad unit testning2005Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    Det första en utvecklare tänker på när man hör de tre magiska orden automatisk unit testning är att han äntligen slipper sitta med den tråkiga testningen. Medan chefen och ekonomiansvarige börjar räkna på hur mycket pengar de kan spara efter de sagt upp halva testavdelningen. Tyvärr får båda tänka om då oftast den automatiska testningen har lika lång utvecklingstid men förhoppningvis om den blir lyckad så förbättrar den kodkvalitén. Vilket kan vara minst lika mycket värt som att man sparar några kronor i minskade personalkostnader.

  • 147.
    sarkar, sanjay kumar
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    A Long Term Evolution (LTE) Downlink (DL) inspired channel simulator using the SUI 3 channel model2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    LTE (Long Term Evolution) is the last step towards the 4th generation of radio technologies designed to increase the capacity and speed of cellular networks. Where at present current generation of cellular technology dominated by 3G (third generation), LTE is marked as 4G. The third generation partnership project (3GPP) currently work for developing the 3rd generation mobile and telecommunication system with a future 4th generation system. This thesis mainly focuses on design of a LTE DL (downlink) inspired channel simulator using the SUI 3 channel model, here OFDM uses as a multiple access scheme. The performance of SUI 3 channel at LTE DL is measured by comparing the AWGN limit.

  • 148.
    Shah, Syed Hamid Ali
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Iqbal, Mudasar
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Hussain, Tassadaq
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Comparison Between WiMAX and 3GPP LTE2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Mobile communication technology evolved rapidly over the last few years due to increasing demands such as accessing Internet services on mobile phones with a better quality of the offered services. In order to fulfil this, wireless telecommunication industry worked hard and defined a new air interface for mobile communications which enhances the overall system performance by increasing the capacity of the system along with improving spectral efficiencies while reducing latencies. For this, two technologies, called Worldwide Interoperability for Microwave Access (WiMAX) and Third Generation Partnership Project Long Term Evolution (3GPP LTE), emerged with an aim of providing voice, data, video and multimedia services on mobile phones at high speeds and cheap rates. In this thesis, we have conducted a detailed comparative study between WiMAX and 3GPP LTE by focusing on their first two layers, i.e. Physical and MAC layer. The comparison specifically includes system architecture, radio aspects of the air interface (such as frequency band, radio access modes, multiple access technologies, multiple antenna technologies and modulation), protocol aspects of the air interface (in terms of protocol architecture, modulation and frame structure), mobility and Quality of Service (QoS). We have also given a brief comparative summary of both technologies in our thesis. In the thesis, we investigated the LTE uplink and performed link level simulations of Single Carrier Frequency Domain Equalization (SC-FDE) and Single Carrier Frequency Division Multiple Access (SC-FDMA) in comparison with Orthogonal Frequency Division Multiplexing (OFDM). The comparison has been in terms of Signal-to-Noise Ratio (SNR) and Symbol Error Rate (SER). In order to verify the theoretical results, we simulated the Peak to Average Power Ratio (PAPR) of SC-FDMA system in comparison with OFDMA. We also simulated the capacity of Multiple Input Multiple Output (MIMO) systems in comparison with Single Input Single Output (SISO) systems. The simulation was performed on a PC running MATLAB 7.40 (R2007a). The operating system used in the simulation was Microsoft Windows Vista.

  • 149.
    Shaikh, Junaid
    et al.
    Blekinge Institute of Technology, School of Computing.
    Fiedler, Markus
    Blekinge Institute of Technology, School of Computing.
    Collange, Denis
    Quality of Experience from End-to-End and Network Perspective2008Conference paper (Other academic)
    Abstract [en]

    Knowing user experience resulting from the performance of network services is an extremely important target for service providers and researchers. Effects of even slight disturbances in network performance were not so damaging for user satisfaction level ever before than they are in today’s changing network conditions in heterogeneous network environment, involving fixed, wireless and mobile networks. Quality of Service (QoS) is the ability of network to provide a service with an assured service level and Quality of Experience (QoE) is how a user perceives the usability of a service when in use. Monitoring the QoS can be an important indicator for the level of user satisfaction if the monitored parameters are strongly correlated to that user satisfaction. This paper presents a comprehensive analysis on the changing user behaviour at different service performance levels through both objective and subjective measurements. At first, it discusses the correlation of subjective grading of the service by users with service performance parameters and observes certain thresholds on the performance parameters where user experience changes. This analysis is based on the results of web surfing experiments on a testbed. Secondly, it discusses the correlation of traffic characteristics of user sessions with session throughputs in order to observe the dependence of these characteristics on network performance metrics. This discussion is based on traffic launched by real users on an ADSL network. Finally, the objectively measured traffic characteristics like user session volumes are compared to subjective responses of the users to see to what extent the session volumes reflect the user satisfaction level.

  • 150.
    Silva, Lakmal
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Xin, Yu
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Mobile Service For the Olympic Games 20082008Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Mobile tourism service applications can be developed and successfully deployed with the rapid developments in mobile phones, communication technologies and tourism. In many situations, when travelers visit a country for a special event or just as travelers, it is obvious that they want to utilize the time and resources efficiently to enjoy the events and visit many places as possible. To achieve this, a traveler needs variety of information to make decisions and travel plans. Traditionally, this means purchasing tour guide books about a county or a city that refer them. At the same time, the 29th Olympic game is coming to the oldest civilized country China in 2008. The goal of our mobile service is to provide needed tourist information of the host country as well as event specific information. In the case of traveling for a special event, it is crucial to be informed about the last minute changes in the schedules. Our implementation tries to address these issues as much as possible.

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