This paper presents ultra-wideband (UWB) indoor propagation channel measurement techniques and results for the parameters of an empirical channel model. To analyze the channel impulse response an improved technique is applied to remove the parasitic effects of the employed hardware properly. The transmission between the ports of a transmit (TX) and receive antenna (RX) is measured with a vector network analyzer (VNA). As the impulse responses of the antennas are deconvolved from the measurements, the channel transfer function in the frequency range of 2-8 GHz can be determined. This approach is applicable as omnidirectional antennas with almost angularly independent impulse responses are used. A statistical model is employed, based on a large database measured in a commercial indoor environment. The measurements include line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios, where the distance between the transmitter and receiver is varied from 1-5.5 m. To characterize small-scale and large-scale statistics of the channel, at each receiver position 25 measurements are accomplished over a grid with 5x5 spatial points.
Abstract. In this paper an approach for indoor localization based on already installed communication transceiver infrastructure is presented. Only marginal additional hardware is required to implement the localization functionality. The idea is to use a power level detection evaluation of the received signals in communication receivers to localize participants. In the planned configuration the power transmitted from mobile terminals is received by a leaky wave cable. Its length and coupling properties are dimensioned according to the dynamic range of two access points connected to the two cable heads. In order to adapt the problem to circuit-based analysis techniques the leaky wave cable is represented by a distributed antenna system. Thereby the considered design consists of a cascade of coupling structures with broadband Vivaldi antennas connected to the coupling ports. An experimental system has been built and also tested using an automated frequency domain measurement setup. Measurement results relating the system bandwidth to positioning accuracy show good agreement with theoretical investigations.
Abstract. An ultra-wideband (UWB) software defined radio (SDR) implementation is presented. The developed impulse radio (IR) transceiver employs first order bandpass (BP) sampling at a conversion frequency which is four times the channel bandwidth. The subsampling architecture directly provides the RF signal avoiding any non-ideal mixer stages and reduces the requirements of digital signal processing implemented in a field programmable gate array (FPGA). The transmitter consists basically of a multi-Nyquist digital to analog converter (DAC), whereas the implemented matched filter (MF) receiver prototype employs a standard digitizing oscilloscope. This design can be adaptively reconfigured in terms of modulation, data rate, and channel equalization. The reconfigurable design is used for an extensive performance analysis of the quadrature phase shift keying (QPSK) modulation scheme investigating the influence of different antennas, amplifiers, narrowband interferers as well as different equalizer lengths. Even for distances up to 7 m in a multipath environment robust communication was achieved.
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