Radio propagation for local loop applications at 2 GHz

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Abstract
Wireless local loop systems-e.g. as one component of PCS-networks-enable a flexible connection of fixed subscribers to network operators. Such systems are applied in urban, suburban and rural areas with base station antennas on local exchange buildings in microcell or macrocell environments. The design and optimisation of these systems is essentially determined by the radio channel properties. One key-point is the time-variability of the radio channel by Doppler shift. Due to fixed subscribers this time-variability is caused mainly by moving scatterers in the surroundings. Measurements show its minor impact on the radio system performance compared to conventional mobile radio systems. Therefore wideband propagation measurements in the 2 GHz frequency range are performed in different realistic scenarios with respect to PCS applications for fixed base station and subscriber station. Measurement results of the wideband complex channel impulse response, data evaluations according to its time-variability and frequency selectivity are presented. These results are applicable to different multiple access schemes like TDMA and CDMA to obtain the necessary system requirements for the air interface, the signal processing algorithms and radio link engineering.