Browsing by Author "Schober, Robert"

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Citation Count: 0
Detection of Multiple Primary Systems Using DAA UWB-IRs
(IEEE, 2009) Erküçük, Serhat; Lampe, Lutz; Schober, Robert
Underlay ultra wideband (UWB) systems have to be able to detect the presence of primary systems operating in the same band for detect-and-avoid (DAA) operation. In this paper the performances of joint and independent detection of multiple primary systems are investigated assuming that the primary systems are potentially dependent (e.g. frequency division duplex uplink-downlink communications). Joint detection is performed based on generating the maximum a posteriori (MAP) decision variables at the receiver where some bias terms are used with these variables in order to achieve a desired trade-off between the detection and false alarm probabilities. Independent detection is performed based on the Neyman-Pearson (NP) test which optimizes system threshold values individually in order to achieve the best detection probability for a given false alarm probability value. When the two detection schemes are compared it is shown that the gain of joint detection depends on the joint system activity values and the considered receiver operating characteristic (ROC) region where the complementary ROC curves illustrate the trade-off between missdetection and false alarm probabilities.
Citation Count: 5
Joint Detection of Primary Systems Using UWB Impulse Radios
(IEEE-INST Electrical Electronics Engineers Inc, 2011) Erküçük, Serhat; Lampe, Lutz; Schober, Robert
Regulation in Europe and Japan requires the implementation of detect-and-avoid (DAA) techniques in some bands for the coexistence of licensed primary systems and secondary ultra wideband (UWB) systems. In a typical coexistence scenario a primary system may have potentially interdependent uplink-downlink communication channels (e. g. simultaneous uplink-downlink communications in a frequency division duplex system) overlapping with the frequency band of a UWB system. If such interdependencies of primary systems' activities are known the UWB system's ability to detect primary systems can be improved. In this study we are interested in determining the possible gains in the detection performance when taking interdependencies into account for practically implementable detection methods. Contrary to selecting the detection thresholds individually for each band as in a conventional detection approach the bands are jointly processed. To this end maximum a posteriori (MAP) decision variables are generated at the receiver and bias terms are introduced to achieve a desired trade-off between the probabilities of detection and false alarm. In addition to finding the optimal detection results based on the Neyman-Pearson (NP) test a suboptimal but practically implementable approach is also considered and the gain compared to conventional independent detection is quantified for various practical scenarios. The results obtained from this study can be used for improving the primary system detection performance of UWB systems as well as for cognitive radios that perform spectrum sensing in multiple bands.