Web-based reference databases and subject gateways to locate current research information in agricultural and food sciences : a Finnish perspective

Selostus: Maatalous- ja elintarviketieteiden www-pohjaiset viitetietokannat ja aihehakemistot - suomalaisen tiedonetsijän näkökulma

Handling of TDM Connections with Cello Media Gateway

UMTS is a 3rd generation telecommunication system, which introduces new network architecture. The change in the network architecture introduces new logical network nodes and changes the role of existing nodes in the network. This architecture changes the current vertically specialized network into a horizontally layered structure. In practice, the layering means that different levels in network hierarchy are separated, and they communicate over well-specified interfaces. The Connectivity Layer, at the bottom of the UMTS network architecture, contains Media Gateways (MGW). The GSM radio access network and UMTS access network are connected to the connectivity network via a MGW. External networks, e.g. ISDN networks, are accessed via other MGWs. The user plane is transported across the connectivity network between/via MGWs. ATM network is used as the backbone in Ericsson’s UMTS core network release 2.0. The main goal of this thesis is to study how the MGW is used to bridge ATM and TDM networks. The Circuit Emulation Service (CES) for ATM is studied, as the conversion from TDM to ATM is made according it. The transportation is made using AAL2 and the issues that it has with voice traffic are studied. The implementation and usage of TDM switching service in MGW are described in detail.

Measuring mobile WAP protocol based services

WAP tulee olemaan tulevaisuudessa tärkeässä roolissa, kun etsitään sopivaa tiedonsiirtoprotokollaa uusille mobiilipalveluille. Vaikka WAP jollain tavalla epäonnistui ensimmäisessä tulemisessaan sen suosio varmasti tulevaisuudessa tulee kasvamaan. WAP:in heikko suosio ei johtunut niinkään protokollan tiedonsiirto ominaisuuksista, vaan WAP-palveluiden kehittymättömyydestä. Tulevaisuuden palvelut kuitenkin ovat kehittyneempiä ja WAP:in suosio tulee kasvamaan. Viimeisimpänä WAP:ia käyttävänä palveluna on esitelty MMS. Kun uudet WAP:iin pohjautuvat palvelut yleistyvät, asettaa se uusia vaatimuksia myös WAP gateway:lle. Työssä tarkastellaan erilaisia mahdollisuuksia mitata mobiilisti WAP palvelujen palvelun tasoa. Työssä myös toteutetaan mobiili WAP palveluiden mittauskomponentti, joka toimii osana laajempaa ohjelmistoa. Tarkoituksena on toteuttaa mittauskomponentti, joka emuloi mahdollisimman hyvin todellista loppukäyttäjää.

Performance Analysis of IP based WSNs in real time systems

Wireless sensor networks (WSNs) are the key enablers of the internet of things (IoT) paradigm. Traditionally, sensor network research has been to be unlike the internet, motivated by power and device constraints. The IETF 6LoWPAN draft standard changes this, defining how IPv6 packets can be efficiently transmitted over IEEE 802.15.4 radio links. Due to this 6LoWPAN technology, low power, low cost micro- controllers can be connected to the internet forming what is known as the wireless embedded internet. Another IETF recommendation, CoAP allows these devices to communicate interactively over the internet. The integration of such tiny, ubiquitous electronic devices to the internet enables interesting real-time applications. This thesis work attempts to evaluate the performance of a stack consisting of CoAP and 6LoWPAN over the IEEE 802.15.4 radio link using the Contiki OS and Cooja simulator, along with the CoAP framework Californium (Cf). Ultimately, the implementation of this stack on real hardware is carried out using a raspberry pi as a border router with T-mote sky sensors as slip radios and CoAP servers relaying temperature and humidity data. The reliability of the stack was also demonstrated during scalability analysis conducted on the physical deployment. The interoperability is ensured by connecting the WSN to the global internet using different hardware platforms supported by Contiki and without the use of specialized gateways commonly found in non IP based networks. This work therefore developed and demonstrated a heterogeneous wireless sensor network stack, which is IP based and conducted performance analysis of the stack, both in terms of simulations and real hardware.