Radio frequency noise measurements and models for indoor wireless communications at 918 MHz, 2.44 GHz, and 4.0 GHz

The authors describe average and impulsive noise measurements inside several office buildings and retail stores. The receiver had a 70 dB dynamic range and operated at 918 MHz, 2.44 GHz, and 4.0 GHz with a nominal 40 MHz 3 dB RF bandwidth. Omni-directional and directional antennas were used to investigate the characteristics and sources of RF noise in indoor channels. Statistical analyses of the measurements are presented in the form of noise level distributions, amplitude probability distributions, pulse duration distributions, and interarrival time distributions. These analyses indicate that photocopiers, printers (line printers and cash register receipt printers), elevators, and microwave ovens are significant sources of impulsive noise in office and retail environments