Browsing Institutt for elektroniske systemer by Author "Ekman, Torbjörn"

Now showing items 1-11 of 11

    • Cluster Based MIMO Radio Channel Modeling 

      Li, Xin (Doctoral theses at NTNU;2020:379, Doctoral thesis, 2020)
      Modeling of wireless channels is perhaps the most complex task in implementing a wireless communication system because wireless channels change over time, vary with frequency and space. That is, the transmit signal with ...

    • Design of a practical and compact mm-wave MIMO system with optimized capacity and phased arrays 

      Cella, Tommaso; Orten, Pål; Ekman, Torbjörn (Journal article; Peer reviewed, 2014)
      In this paper we evaluate the feasibility of short range outdoor mm-wave MIMO links in the 70 GHz portion of the E-band (71–76 GHz). We use phased arrays in order to strongly reduce the impact of the multipath components, ...

    • Detection of radio interference in the UHF amateur radio band with the Serpens satellite 

      Quintana-Diaz, Gara; Nodar-López, Diego; González Muíño, Alberto; Aguado Agelet, Fernando; Cappelletti, Chantal; Ekman, Torbjörn (Peer reviewed; Journal article, 2021)
      High packet losses when uplinking commands to small satellites have been reported in the UHF amateur band (430–440 MHz) since late 2013. Measurements of the uplink radio environment have shown high levels of in-band ...

    • Effective Channel Hardening in an Indoor Multiband Scenario 

      Ghiaasi, Golsa; Abraham, Jens; Eide, Egil; Ekman, Torbjörn (Journal article; Peer reviewed, 2019)
      We evaluate channel hardening for a large scale antenna system by means of indoor channel measurements over four frequency bands, 1.472 GHz, 2.6 GHz, 3.82 GHz and 4.16 GHz. NTNU’s Reconfgurable Radio Network Platform has ...

    • In-orbit Interference Measurements and Analysis in the VDES-band with the NorSat-2 Satellite 

      Quintana Díaz, Gara; Birkeland, Roger; Løge, Lars; Andersen, Even; Bolstad, Anton; Ekman, Torbjörn (Peer reviewed; Journal article, 2022)
      Maritime activity in the Arctic is increasing, triggering a need for better communication infrastructure. With limited terrestrial infrastructure available, satellite services are essential for distributing maritime safety ...

    • In-orbit measurements and analysis of radio interference in the UHF amateur radio band from the LUME-1 satellite 

      Quintana Díaz, Gara; Ekman, Torbjörn; Lago Agra, José Miguel; Hurtado de Mendoza, Diego; González Muíño, Alberto; Agelet, Fernando Aguado (Journal article; Peer reviewed, 2021)

    • Increasing sum-rate in large-scale cognitive radio networks by centralized power and spectrum allocation 

      Vijayandran, Luxmiram; Byun, Sang-Soon; Øien, Geir Egil; Ekman, Torbjörn (Journal article; Peer reviewed, 2012)
      We revisit the widely investigated problem of maximizing the centralized sum-rate capacity in a cognitive radio network. We consider an interference-limited multi-user multi-channel environment, with a transmit sum-power ...

    • Methods for Finite Massive MIMO Analysis 

      Abraham, Jens (Doctoral thesis, 2022)
      Massive MIMO is a core technology for 5G cellular networks, that matured from a concept to commercial implementations over the last decade. It uses large-scale antenna systems to provide unprecedented access to the spatial ...

    • A Multi-purpose Software Defined Radio Payload for the HYPSO-2 Satellite 

      Birkeland, Roger; Quintana Díaz, Gara; Honoré-Livermore, Evelyn; Ekman, Torbjörn; Agelet, Fernando Aguado; Johansen, Tor Arne (Peer reviewed; Journal article, 2022)
      Recent developments in flexible Software Defined Radio (SDR) platforms provide researchers with a framework for small satellite missions that combine several parallel objectives. A part of the mission for the HYPer-spectral ...

    • Satellite uplink interference measurements in the 437 MHz UHF amateur radio band onboard LUME-1 

      Quintana Diaz, Gara; Ekman, Torbjörn; Camanzo, Alejandro; Birkeland, Roger; Lago, José Miguel; Muíño, Alberto González; Aguado, Fernando (Peer reviewed; Journal article, 2023)
      Satellite operators struggle to communicate with their satellites over Europe in the UHF amateur band (430–440 MHz) due to high power in-orbit interference. Statistical characterisation of the interference beyond average ...

    • Statistics of the Effective Massive MIMO Channel in Correlated Rician Fading 

      Abraham, Jens; Ramírez-Espinosa, Pablo; Ekman, Torbjörn (Peer reviewed; Journal article, 2022)
      Massive multiple-input multiple-output base stations use multiple spatial diversity branches, which are often assumed to be uncorrelated in theoretical work. Correlated branches are seldom considered since they are ...