Helsinki University of Technology

Latest Content From Helsinki University of Technology

Whitepaper: MIMO-OFDM

by Helsinki University of TechnologyJan 01, 2008

The growing demand of multimedia services and the growth of Internet related contents lead to increasing interest to high speed communications. To obtain diversity, the signal is transmitted through multiple (ideally) independent fading paths e.g. in time, frequency or space and combined constructively at the receiver. Multiple Input-Multiple-Output (MIMO) exploits spatial diversity by having several transmit and receive antennas.

Whitepaper: Municipal WLAN: Case Examples In Finland

by Helsinki University of TechnologyJan 01, 2008

This research paper from Helsinki University of Technology concentrates on current WLAN cases especially from the viewpoint of different cities and municipalities. Framing of the paper has been made for only current WLAN cases in Finland. This paper presents three leading municipal involved WLAN cases in Finland: SparkNet, PanOULU and Mastonet. In addition the paper also introduces other smaller and newer network cases which are related to municipal WLAN development.

Whitepaper: Tracking Based Material Flow Transparency For Small and Medium Sized Enterprises

by Helsinki University of TechnologyJan 01, 2008

Efficient supply chain management demands transparency for inventory and deliveries along the whole supply network. This research paper from Helsinki University of Technology identifies the distinct difficulties small and medium sized enterprises experience with the prevalent solutions for material flow transparency. A lean, tracking based approach is proposed that enables integration of small and medium sized enterprises within multi-company supply networks. The technical feasibility and applicability of the proposed approach are discussed on the basis of data gathered in two pilot installations and three case studies.

Whitepaper: Encrypted Watermarks and Linux Laptop Security

by Helsinki University of TechnologyJan 01, 2008

The most common way to implement full-disk encryption (as opposed to encrypted file systems) in the GNU/Linux operating system is using the encrypted loop device, known as CryptoLoop. This paper demonstrates clear weaknesses in the current CBC-based implementation of CryptoLoop, perhaps the most surprising being a very simple attack which allows specially watermarked files to be identified on an encrypted hard disk without knowledge of the secret encryption key. Disk encryption is not a performance bottleneck nor does it significantly decrease the usability of the system. Therefore there are few excuses for not deploying it where ever possible.

Whitepaper: The Impact Of Referents On Entrepreneurship

by Helsinki University of TechnologyJan 01, 2008

The foundation of this paper is the assumption that social constructionism offers a fruitful theoretical perspective within which growth phenomena of small companies in information intensive industries can be understood. The perspective helps to understand where the growth oriented mindset that guides the managers of entrepreneurial companies originates from. The paper applies the perspective and other complementary cognitive and motivational theories upon the question of how the growth orientation of management is born and further how growth orientation together with management mental models affect growth of small software companies.

Whitepaper: A Multi-Level TCP Model With Heterogeneous RTTs

by Helsinki University of TechnologyJan 01, 2008

This paper published by Helsinki University of Technology studies TCP performance focusing on the mean flow transfer delay and the average number of concurrent flows in the system. This is done for a dynamic population of users, rather than a static number of permanent flows. The modeling approach relies on using idealized processor sharing models as a starting point and modifying their properties to take into account some of TCP?s non-ideal behavior. To this end, a model is derived that incorporates the effect of packet losses and RTTs on the good put, as well as limited sending rates.

Whitepaper: Jamming Resistant Architecture for WiMAX Mesh Network

by Helsinki University of TechnologyJan 01, 2008

The paper presents a jamming resistant architecture for military applications of WiMAX (802.16) mesh network. The main idea is to use multiple Base Stations (BS), access points to the fixed core network. This will facilitate network survivability both in case of BS destruction and in case of jamming. When the nodes are affected by jamming they can reroute to another base station if possible. The multiple BS architecture requires distributed scheduling as there is no single point of control that can execute centralized scheduling.