Showing papers by "Timo Hämäläinen published in 1998"
08 Sep 1998
TL;DR: TUTMAC is connection oriented: the bandwidth is allocated deploying constant bit-rate TDMA based data channels that are reserved by exchanging short control messages that can be dynamically altered during the data exchange session.
Abstract: This paper presents a medium access control (MAC) protocol called TUTMAC for a new wireless local area network (TUTWLAN). The design objective has been to develop a simple, multimedia service capable protocol that provides sufficient medium utilisation efficiency and guarantees QoS (quality of service) parameters. The developed system utilises a centralised (base station controlled) network architecture. A limited number of portable stations can be associated with the same base station, i.e. in the same TUTWLAN cell. TUTMAC is connection oriented: the bandwidth is allocated deploying constant bit-rate TDMA based data channels that are reserved by exchanging short control messages. The connection parameters can be dynamically altered during the data exchange session. Currently, a TUTWLAN prototype is being developed comprising both TUTMAC software and platform hardware modules. The prototype will support up to eight simultaneous data-transfer connections each having 64 to 512 kbit/s data transmission bandwidth.
32 citations
08 Sep 1998
TL;DR: A security scheme for a medium access control protocol in a new wireless local area network TUTWLAN (Tampere University of Technology WLAN) that provides both privacy of wireless data communications and the authenticity of communicating parties.
Abstract: This paper presents a security scheme for a medium access control protocol in a new wireless local area network TUTWLAN (Tampere University of Technology WLAN). The design objective has been to develop a security scheme that will be scalable for various needs and offer high security for demanding applications. The designed security scheme provides both privacy of wireless data communications and the authenticity of communicating parties. Our authentication scheme allows also the communicating entities to establish a shared secret key for secure communication session. Data security schemes have also been introduced. There are three optional data security modes that offer flexible ciphering and data security level.
22 citations
02 Sep 1998
TL;DR: Mapping of Kanerva’s Sparse Distributed Memory is presented for a partial tree shape neurocomputer and rowwise mapping parallelized the activation mechanism so that it is better in slower activation methods or when needed a very fast writing procedure.
Abstract: Mapping of Kanerva’s Sparse Distributed Memory (SDM) is presented for a partial tree shape neurocomputer. We discuss the original model and give a detailed parallel mapping for improved SDM models, using Karlsson’s activation mechanism and efficient reading methods. Both row-wise and column-wise mappings can be effectively used, but column-wise mapping is analysed in more details because it minimizes communication in the improved read operation. Instead, rowwise mapping parallelized the activation mechanism so that it is better in slower activation methods or when needed a very fast writing procedure. Performance analysis deals with SDM matrix sizes, memory capacity and load balance.
1 citations