TKK | Tietoverkkolaboratorio

The Research Seminar for Dept. Communications and Networking

The presentations (future first). If no other information is given, the presentations are at E208, 2:30pm.

Some information about organization at the bottom of the page.

Day and place	Presenter	Topic	Host
Thu18.12.2008 G317	Hannu Verkasalo	Handset-based analysis of mobile service usage: Method, Applications, and Implications
28.11.2008 G317	Marko Luoma	about Ethernet
14.11.2008 G317	Mikko Pitkänen	Data Availability in the Grid and Challenging Networking Environments
31.10.2008 G317	Dr. Jose Costa-Requena Nokia	Nokia Home Connectivity UPnP based applications available in existing devices with WLAN and future plans in that area.	Jouni Karvo
24.10.2008 G317	Dr. Pirkko Kuusela VTT	Spanning tree approach for dependability	Jouni Karvo
17.10.2008 G317	Doc. Kalevi Kilkki	Communications Ecosystem
3.10.2008 G317	Janne Lindqvist	Privacy of Mobile Computers: Chattering Laptops and Protecting Privacy with Protocol Stack VirtualizationGlobal Information Infrastructure/Next Generation Networks Mobile computer users often have a false sense of anonymity when they connect to the Internet at cafes, hotels, airports or other public places. We have analyzed information leaked by mobile computers to the local access link when they are outside their home domain. We found that all layers of the protocol stack leak various plaintext identifiers of the user, the computer and their affiliations to the local link, which a casual attacker can observe. We propose two independent mitigation mechanisms for these leaks: network location awareness can be used to prevent unnecessary service discovery attempts and protocol stack virtualization provides isolation for the traffic sent to the network, for example, every application uses a distinct identifier space on all layers of the protocol stack.	Jouni Karvo
13.6.2008 D302	Prof. Joaquim E Neves University of Minho, Portugal	Global Information Infrastructure/Next Generation Networks By definition, the Global Information Infrastructure (GII) will be an infrastructure which facilitates the development, implementation and interoperability of existing and future information services and applications within and across the telecommunications, information technology, consumer electronics and content provision industries. A Next Generation Network (NGN), as a packet-based network, is able to make use of multiple broadband, QoS-enabled transport technologies to provide Telecommunication Services to users: the service-related functions are independent of the underlying transport-related technologies and supports generalised mobility which will allow consistent and ubiquitous provision of services to users. Presentation
30.5.2008	Pasi Sarolahti	Future Internet Research in Nokia Research Lablet
23.5.2008	Olli Pottonen	The perfect binary codes of length 15 Perfect codes, such as the Hamming codes, are an interesting class of error-correcting codes. By using a combinatorial approach and utilizing the classification of Steiner quadruple systems, a complete classification of the perfect binary codes of length 15 is achieved.
16.5.2008	Vesa Vaskelainen	Settling the optimality question of the Steiner triple covering problem A135 Optimality of the best known solution for a difficult set covering problem A135 that arises from a Steiner triple system of the order of 135 has been an open problem last decade. The question can be settled with reasonable computational time by utilizing the orbits of subsets in the pruning of the search space.
9.5.2008 10:30	Mauri Honkanen, Nokia Research Center	Internet of Things	Riku Jäntti
9.5.2008 S1 12:00	Juha Leino	FLOW-LEVEL PERFORMANCE ANALYSIS OF DATA NETWORKS USING PROCESSOR SHARING MODELS Doctoral dissertation	Jorma Virtamo
25.4.2008	Dr. Simone Leggio Nokia Devices	Open Source development for embedded linux devices. A general introduction and a use case: the telepathy framework	Jukka Manner
18.4.2008 S4 12:00	Ilmari Juva	TRAFFIC MATRIX ESTIMATION IN THE INTERNET: MEASUREMENT ANALYSIS, ESTIMATION METHODS AND APPLICATIONS Doctoral dissertation	Jorma Virtamo
28.3.2008 14:00	Mika Kukkonen Senior Specialist, Open Source, Nokia Siemens Networks	Impact of Open Source to Software Development in Nokia Siemens Networks Open Source software is easily seen as a way to lower R&D costs, and so is an attractive choice in modern communications industry. Still, the "free" software does not come without a price. In this presentation some of these hidden costs and long term effects are briefly presented. Finally some software research areas in Nokia Siemens Networks are highlighted on the topic level.	Jukka Manner
7.3.2008	Dr. Samuli Aalto	SRPT applied to bandwidth-sharing networks My presentation will be based on a forthcoming paper by Samuli Aalto and Urtzi Ayesta, to appear in Annals of Operations Research, Special Issue: "Stochastic Performance Models for Resource Allocation in Communication Systems" Abstract: We consider bandwidth-sharing networks, and show how the SRPT (Shortest Remaining Processing Time) discipline can be used in order to improve the delay performance of the system. Our main idea is not to use SRPT globally between the traffic classes, which has been shown to induce instability, but rather deploy SRPT only locally within each traffic class. We show that with this approach, the performance of any stable bandwidth allocation policy can be improved. Importantly, our result is valid for any network topology and any flow size distribution. A numerical study is included to illustrate the results. Presentation
8.2.2008	Dr. Pasi Lassila	Combining channel-aware and age-based scheduling in HSDPA systems We analyze the impact of size-based scheduling on the flow level performance of elastic traffic in wireless downlink data channels. In the case, where the scheduler only has information about the averate rate of the users' channels, the gains from employing flow-level size information can be significant. However, when instantanous rate variations (e.g., due to fast fading) are taken into account, the scheduler must simultanously utilize instantaneous rate information and the flow-size information. We experiment with several different approaches for utilizing rate and size information. Some numerical results are shown, where the tradeoffs between the two types of information are explored.
1.2.1008 14:00	Prof. Jukka Manner	UFOs on the Internet
25.1.2008	M.Sc Young Ju Hwang, Yonsei University, Korea	On the achievable capacity of network coding with carrier-sensing MAC protocol. It is known that coding over wired networks increases spectral efficiency, reducing the required number of transmissions. However, the properties of wireless networks, such as omni-directional transmissions and interference, make the gain of network coding different from that in wired networks. In wireless networks, network coding strongly reflects interactions with underlying MAC protocols, and recently many researchers jointly study on network coding with MAC of scheduling. Starting from the same motivation as above, however, we take a different viewpoint in this study. We investigate the gain of network coding using spectral radius analysis, based on carrier-sensing MAC protocol such as CSMA/CA. For the purpose, we firstly analyze if there exists an optimal forwarding factor, which means the ratio between the number of packets transmitted and the number of packets received, per node.	Riku Jäntti
18.1.2008	Dr. Petteri Mannersalo, VTT	Power management in large wireless ad hoc networks: is it worth doing? In an ad hoc network, important performance measures include connectivity, capacity, and energy consumption. Compared to the uniform power allocation where each node has same transmission power, the optimized power configuration may result in large savings in energy usage without losing the connectivity or capacity of the network. In this talk, we introduce and analyse a distributed algorithm which converges to the optimal power configuration for a given initial connectivity graph defined e.g. by the maximal powers at each node.	Jouni Karvo
11.1.2008	M.Sc. Matti Vesterinen, Nokia Siemens Networks	XMPP - Extensible Real-Time Services Traditionally Extensible Messaging and Presence Protocol (XMPP) has been thought to be the "Linux of instant messaging". However, Internet service providers, such as Google, Twitter and Jaiku, have proved that XMPP is suitable for a wide variety of near real-time services. While XMPP is easily extensible, it is also extremely efficient compared to Session Initiation Protocol (SIP). That combined with the complexity of SIP have made XMPP a respectable solution also for mobile and fixed operators. Presentation	Seppo Saastamoinen
2007
30.11.2007	prof. Olav Tirkkonen	Feedback Partitioning for Wireless Communication In modern cellular communication systems, channel feedback is used in multiple ways to improve the link between transmitter and receiver. Related to the physical layer, the most pertinent types of feedback are 1) Channel Quality Indication (CQI) feedback, where the receiver suggests the best Modulation and Coding Scheme to be used. 2) ACK/NACK feedback, related to a Hybrid ARQ retransmission protocol 3) multiantenna feedback, where the received SINR is improved by properly selecting the antenna configuration at the transmitter (so-called precoding). In this talk, the characteristics of these three kinds of feedback are first discussed. Related to multiantenna feedback for multistream MIMO systems, splitting of precoding to beamforming and orthogonalization parts is considered. The problem of feedback partitioning is presented: a limited amount of bits has to be partitioned between these types of feedback. Metrics for feedback partitioning, as well as initial results, are discussed.
23.11.2007	prof. Raimo Kantola	Post IP networking It is becoming more and more evident that IP does not meet customer requirements anymore. A lot of effort is spent on patching up IP networks with ever new tricks that break the original IP principles. Dave Clark has formulated that from the End to End principle we have moved to Trust to Trust. Moreover, the original assumption that receivers wish to receive what senders are sending (or otherwise they would not send) does not hold either. The talk will discuss the problem and outline a solution (without going to details) that we are pursuing in a forthcoming EU project. The discussion hopefully will enlighten us on why any solution would succeed.
16.11.2007	Dr. Jyri Hämäläinen	On the Impact of Control Imperfections The efficiency of wireless mobile systems can be greatly improved by using the channel state information in the transmitter. Well-known theorethical results promize large gains for e.g. transmit diversity and scheduling methods especially when SNR is large in receiver. Yet, from practical investigations related to development of systems like WCDMA, HSPA, 3G LTE and IEEE802.16e it is known that imperfect feedback information may seriously degrade the system performance and even destroy theorethical gains. In presentation we examine some examples that are inspired by practical systems. Aim is to show that impact of control imperfections can be also investigated by theorethical means.
9.11.2007	prof. Patric Östergård	Discrete Objects and Algorithms Whereas much of the research in our labs is application-oriented, or at least applied, my own work is almost entirely basic research. However, my knowledge in (construction and classification of) discrete structures and development of algorithms for hard combinatorial problems could probably turn out useful now and then in studies by other people done in the laboratory. After all, discrete mathematics is the mathematics of the digital, communicating world. In this presentation I'll give an overview of the main themes of my work and interest.
2.11.2007	prof. Jörg Ott	DTN-based Content Storage and Retrieval Delay-tolerant networking (DTN) enables nodes to communicate by means of asynchronous messaging without the need for an end-to-end path. Suitably designed application protocols may operate in DTNs by minimizing end-to-end interactions and using self-contained messages for communication. The store-carry- and-forward operation and message replication of many DTN routing protocols may result in multiple copies of messages spread across many nodes for an extended period of time. We leverage these properties for application support in (mobile) intermediate DTN nodes which act as ad-hoc routers. We add explicit application hints to messages that are visible to each node, allowing them, e.g., to cache content, act as distributed storage, or perform application-specific forwarding.
29.10.2007	prof. Heikki Hämmäinen	First the presentation gives a brief overview to the research topics of my networking business team. Then the actual substance concentrates around the demand side analysis of new services. The traditional concept of positive network effects is presented via examples. Based on that, the concept of two-sided markets and platforms is then described. This novel theory has interesting implications for instance in the regulatory deciison-making.
19.10.2007 D302	prof. Jorma Virtamo	Minimum Transmission Energy Trajectories for a Linear Pursuit Problem We study a pursuit problem in the context of a wireless sensor network, where the pursuer trying to capture a pursuee moving with constant velocity is always directly communicating with a sensor node in the near proximity of the pursuee. Assuming that the sensor nodes can adjust their transmission power depending on the distance between the pursuer and pursuee according to the usual power law, P~d^a, the task is to find the optimal trajectory of the pursuer minimizing the total transmission energy. We approach this classical control theoretic problem by the method of dynamic programming. The optimal trajectories can be solved numerically. The qualitative behavior of the trajectories is discussed.
12.10.2007 D302	prof. Riku Jäntti	Wireless sensor and actuator networks - cross layer design issues As the interest of automation industry rises towards different networked systems; also wireless communication becomes an option for data transmission in control systems. Networking solutions in automation dramatically decrease costs as every sensor and actuator do not have to be separately wired to the control room. Wireless solutions would make the systems even more flexible and cost effective. Wireless provides appealing opportunities for measuring in industrial systems, but closing the loop over wireless (control) also involves some threats that need further research. The well known problems arising from wireless networking are varying time-delays and packet losses in communication. The traditional control theory assumes constant sample times and it is not well suited for asynchronic systems such as Wireless Networked Control Systems. Thus we need to develop new theory to deal with integrated wireless communications and control, but obviously we are simultaneously obliged to develop simulation platforms for testing and verifying the theories before implementing them on real industrial systems. Based on widely used simulation software tools such as MATLAB/Simulink (control design) and ns-2 (communications), we will develop a platform for evaluating and demonstrating interactions of wireless communications and embedded control systems. The platform supports pure simulation and hardware-in-the-loop simulation of communication protocols and control algorithms on hardware.
14.9.2007 D302 14:00	prof. Yrjö Neuvo	Wireless Future Trends and Challenges
7.9.2007 D302	Dr. Georgios Paschos, VTT	Sleep mode for WiMAX networks Standards 802.16e have defined a mechanism for power saving. I will describe the mechanism, and then I will present some work I have been doing on that.	Jouni Karvo
24.8.2007 D302	Dr. Huizhen Yu, HIIT	Recent Works on MDP and POMDP In this talk I will present some of my recent works on partially observable Markov decision processes (POMDP) and on reinforcement learning in Markov decision processes (MDP). For POMDP I will address lower bounds of the optimal average cost function and near-optimality of finite-state controllers, both of which are useful in approximately optimal control. For MDP I will address efficient least squares-based temporal difference learning algorithms for approximating the cost function of polices. The talk will focus more on general ideas than technical details.	Jorma Virtamo
15.6.2007 D302 15:00	Dr. Lars Eggert, Nokia	An Experimental Evaluation of Voice Quality over the Datagram Congestion Control Protocol Most Internet telephony applications currently use either TCP or UDP to carry their voice-over-IP (VoIP) traffic. This choice can be problematic, because TCP is not well suited for interactive traffic and UDP is unresponsive to congestion. The IETF has recently standardized the new Datagram Congestion Control Protocol (DCCP). DCCP has been designed to carry media traffic and is congestion- controlled. This paper experimentally evaluates the voice quality that Internet telephony calls achieve over prototype implementations of basic DCCP and several DCCP variants, under different network conditions and with different codecs. It finds that the currently- specified DCCP variants perform less well than expected when compared to UDP and TCP. Based on an analysis of these results, the paper suggests several improvements to DCCP and experimentally validates that a prototype implementation of these modifications can significantly increase voice quality.	Jörg Ott
25.5.2007 D302	Nicklas Beijar	Mobile Peer-to-Peer The talk will discuss the challenges and opportunities of peer-to-peer applications in mobile networks and give an overview over the research on mobile peer-to-peer in the Networking laboratory.
4.5.2007 D302	prof. Bronwyn Howell, Victoria University of Wellington	The Tale of Two Telco Markets - initial impressions on the state of play in the Finnish and New Zealand markets	Heikki Hämmäinen
2.5.2007 E111 11:00	prof. Evsey Morozov, Petrozavodsk University	Stability analysis of backoff protocols and retrial queues We present stability analysis of backoff protocols and a wide class of multiserver retrial queues. Under mild assumptions stability condition of a wide class of back-off protocols with general backoff function describing transmission mechanism in N-station network is presented. Also optimality condition of backoff protocol minimizing expected transmission time is given. Asymptotic analysis as N goes to infinity is discussed. (The work by A.Lukianenko, PhD student, Kuopio U.) Moreover, we show that multiserver retrial queues with general service time and renewal input of primary calls are stable under the same conditions which imply stability of the corresponding multiserver queues with infinite buffer. An important element of the analysis is the regenerative property of the basic queueing process and a characterization of the limiting unfinished regeneration time.	Jorma Virtamo
27.4.2007 D302	prof. Carsten Bormann, Univ. Bremen	Header Compression: Overview and current work Since RFC 1144 (Van Jacobson header compression) in 1990, header compression has been used to make existing packet protocols work better over limited-performance links and to make the design of new packet protocols less dependent on the characteristics of such links. The talk will give a quick overview over the last decade of IETF work on header compression and then look at a couple of current works in progress.	Jörg Ott
26.4.2007 D302	prof. V. Sridhar, MDI, India	Techno-Economic Characteristics of Mobile Communication Services in Developing Countries: Case of India Quick deployment, competition, advancement in technologies, and reduced cost of access have propelled the growth of mobile services in India much like in other developing countries. While the fixed line subscriber base in India is saturated at around 50 million, the mobile subscriber base is growing at a compounded annual rate of over 90 percent and has reached about 155 million. However, the techno-economic characteristics of these evolving mobile markets are very different from matured markets. Lower Average Revenue Per User, lower call charges, high regulatory and interconnect levies and low call volumes create challenges for policy makers, operators, equipment and handset manufacturers. The talk will focus on issues and challenges for creating successful business models in such an environment. The use of diffusion models and technology acceptance models in the study of growth and adoption of mobile services will also be discussed.	Heikki Hämmäinen

Organization

Typically we ask our contacts in the industry, visiting scholars, and our own researchers to give presentations, and hope to have some discussion afterwards. The presentations are expected to last from twenty minutes to two hours, preferably around 45min. After the presentation, discussion can last arbitrarily long, as people that are not so interested can leave during the discussion without disturbing the event too much.

Tietoverkkolaboratorio on nyt osa Tietoliikenne- ja tietoverkkotekniikan laitosta. Tällä sivulla oleva tieto voi olla vanhentunutta.