The characteristics of the transmission medium play an important part in determining the performance of a communications system. We have already discussed the influence of the channel over the mobile radio signal in Chapters 2 and 3, but we also have to consider noise. Although research engineers are interested in understanding the nature of the noise so that it can be satisfactorily characterized, the more important aspect from a practical point of view is the ability to predict the performance of communication systems that have to operate in the presence of noise.

Man-made noise

This paper describes in detail the criteria for the design of a mobile laboratory for the characterization and measurement of manmade electromagnetic noise in the urban, suburban, and rural environment. A significant difference from previous similar measurements is the bandwidth of the receiving system, which is here of the order of 1 MHz. A simple model is proposed to describe the impulsive noise together with a series of experiments to validate the model and determine the significant necessary parameters. The detailed requirements for each of the subsystems of the mobile laboratory are discussed and some typical results obtained in trial runs are presented.

A Mobile Wide-Band Measurement System for Urban Man-Made Noise

This paper describes in detail the criteria for the design of a mobile laboratory for the characterization and measurement of man-made electromagnetic noise in the urban, suburban, and rural environment. A significant difference from previous similar measurements is the bandwidth of the receiving system, which is here of the order of 1 MHz. A simple model is proposed to describe the impulsive noise together with a series of experiments to validate the model and determine the significant necessary parameters. The detailed requirements for each of the subsystems of the mobile laboratory are discussed and some typical results obtained in trial runs are presented.

http://ieeexplore.ieee.org/iel5/25/34015/01622174.pdf

A mobile wide-band measurement system for urban man-made noise

Modern measurement campaigns of man-made radio frequency (RF) noise have reported results from fixed locations that are assumed to be representative of the surroundings. Models derived from these measurements include parameters to express the variability in time and in space over very large distances (i.e., differences between cities). Despite the rapidly evolving mixture of noise sources, especially in modern urban environments, spatial variation of RF noise power at the scale of streets and blocks is essentially unknown in the very high frequency and ultra high frequency bands. Using a portable calibrated noise measurement system of our design, RF noise was recorded over a 1-MHz bandwidth for frequencies of 142.0, 246.5, and 972 MHz. Noise surveys were conducted during daytime working hours in two different neighborhoods within Boston, Massachusetts, USA, with each survey transiting a fixed, several kilometer long route, repeated twice to enable separation of temporal from spatial variability. Significant and spatially repeatable variations in median power, peak power, and voltage deviation were observed over distances of tens to hundreds of meters, dependent upon the measurement frequency. The observed spatial patterns of median and peak power appear to be repeatable on timescales of hours to weeks, and likely beyond, suggesting that these noise patterns are persistent features of the urban environment.

/pdf/street-scale-mapping-of-urban-radio-frequency-noise-at-very-5aw7cp6gya.pdf

Street-Scale Mapping of Urban Radio Frequency Noise at Very High Frequency and Ultra High Frequency

The error performance of multi-transmitter data systems is described for mobile and stationary users in overlap areas, as a function of carrier frequency and modulation timing difference. Plots of bit error rate and error distribution are given, and the conclusion is reached that performance is comparable to single transmitter systems at the same signal level. The constraints on the choice of data modulation are discussed

http://ieeexplore.ieee.org/iel5/5266378/5269750/05269753.pdf

J.H. Sangster

Papers

The effects of fading and impulse noise on digital transmission over a land mobile radio channel