August 1999 | NTIA Technical Report TR-99-369
Perry F. Wilson; Peter B. Papazian; Michael G. Cotton; Yeh Lo
Abstract: An advanced antenna test bed for evaluating adaptive antennas and next-generation mobile communication systems is described. The key elements of the data acquisition system are 8 simultaneous channels, broadband impulse channel sounding, high speed analog to digital data conversion and storage, and flexible post processing. Mobile channel sounding measurements were made in two sectors at 1920 MHz using 4 receiving antennas. Received signal strength and transmission loss are examined. Path loss exponents for the two sectors are found to be 4.89 and 4.08. These are typical for urban to suburban environments. RMS delay spreads for the two sectors are found to be less than 1.38 µs and 0.65 µs at the 90% probability level and 3.14 µs and 1.35 µs at the 99% probability level respectively. Fast fading reduction using antenna diversity (up to 4 antennas) and increased channel bandwidth (19.6 kHz, 1.25 MHz, 5.0 MHz, and 10.0 MHz) is examined. Three signal combining methods are considered: selection diversity, equal gain combining, and maximal ratio combining. Measured results indicate that increasing the number of diversity antennas or the channel bandwidth significantly reduces fading. Maximal ratio combining yields the largest diversity gain exceeding 11.0 dB and 17.0 dB at the 90% and 99% fast fade depth probability levels respectively when all four channels are used.
Keywords: transmission loss; adaptive antennas; power delay profiles; RMS delay spread; wideband measurements; advanced antenna test bed; equal gain combining; fast signal fading; impulse channel sounding; maximal ratio combining; selection diversity
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Peter B. Papazian
Institute for Telecommunication Sciences
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