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Communications computing

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  • Electrical and electronic engineering [2]
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  • Communication system theory [2]
  • Multiple access communication [2]
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  • Radio links and equipment [2]
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Simulation of S-UMTS system
Author(s): M.A.K. Sumanasena, B.G. Evans, R. Tafazolli
Source: Simulation and Modelling of Satellite Systems, 2002, p. 4 - 4
Type: ConferencePaper
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This paper presents simulation aspects of the standard satellite universal mobile telecommunication system (S-UMTS) air interface and the generic models used for the simulation of the physical layer. It is very important to validate the accuracy of the individual models before combining them. Therefore, a full description of the important models for parameters such as modulation, encoding, interleaving and rate matching is presented, together with the performance comparison with the theoretical/expected results. Having justified the accuracy of these models, a complete physical layer is then developed by combining these individual models. A system corresponding to the satellite wideband code division multiple access, SW-CDMA (as proposed for S-UMTS standardisation by the European Space Agency, ESA), with suitable modifications, has been considered as a reference system. Performance evaluation of the proposed adaptive physical layer was carried out in a lightly wooded environment. The average BER of 6.4×10-4 is less than our target of 10-3. In addition, throughput was improved from 35 kbps (conventional system) to 44.5 kbps (adaptive system). (5 pages)

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Band sharing between CDMA based non-geostationary satellite-PCNs
Author(s): H.M. Aziz, R. Tafazolli, B.G. Evans
Source: Fifth International Conference on Satellite Systems for Mobile Communications and Navigation, 1996, p. 97 - 101
Type: ConferencePaper
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The demand for global telephony services for mobile users requires the use of constellations of non-geostationary orbits. The proposed S-PCNs are Iridium, Inmarsat-P, Globalstar, Odyssey and Ellipse. The first two systems propose to use a time division multiple access (TDMA) scheme and the others code division multiple access (CDMA) scheme. It is claimed that CDMA based S-PCNs can share the allocated frequency bands due to the interference resistant property of CDMA. Spectrum sharing must be based on defined interference criteria being satisfied. The interference events are based on the statistics of the C/I. For this a computer simulation was developed to model the dynamic nature of any constellation, and produces all the statistical values of the C/I to a mobile in a fading channel. The simulation includes constellations the results of proposed S-PCNs with multi-spotbeam antennas (MBA). We present the results of the investigation on the effect of totally overlapped band sharing on the bandwidth utilisation and resultant capacity and compare this capacity with that of a band segmentation approach. Computed values of the C/I in totally overlapped band sharing and segmented band sharing scenarios are translated into the system capacity. The results lead to specific criteria which must be satisfied for band sharing.

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