A new approach for considering the interference impact on digital radio systems from complex interference environments
Doktorsavhandling, 2007

Interference from electrical equipment can severely degrade a co-located digital radio receiver. To avoid such performance degradation, it is necessary to have estimation methods to predict the influence of an interference environment on a radio receiver. In order to protect radio services, electrical equipment must fulfill international standards regarding maximum allowed levels of radiated electromagnetic energy. Unfortunately, present emission requirements are not developed to protect digital radio receivers. This work considers the influence of electrical equipment on digital radio receivers. As interference generated from electrical equipment often has a non-Gaussian amplitude probability distribution, the commonly used Gaussian approximation is not always applicable for performance analysis. Thus, a practical method of estimating the performance degradation is necessary for this kind of interference. Amplitude probability distribution (APD) of an interference signal has earlier been shown to be correlated to the impact on a digital radio receiver. In this thesis, the use of this measure in conventional expressions of the error probability is clarified. It is also shown that the relationship between the measured APD of an interference source and the maximum degradation, in terms of bit error probability, of the receiver can be deployed for emission requirements. On the basis of these results, a new method of defining emission requirements is proposed. The method is developed for both uncoded systems and systems that use forward error-correction codes. The direct use of the measured APD of an interference source for performance estimation of a radio system requires that the bandwidths of the measuring and the radio receiver under investigation are approximately the same. When this is not the case, a solution is presented that demonstrates how to convert the APD measured by one bandwidth to an APD that is valid for another bandwidth. The conversion of the APD to another bandwidth is developed for a certain type of noise. Furthermore, the thesis treats the practical problem to achieve an approximate value of the coding gain for binary phase shift keying (BPSK) system with convolutional codes in an impulsive interference environment, which is essential for deriving emission requirements for communication systems using such kind of error-correction codes.

minimum shift keying

class A

amplitude probability distribution

bandwidth conversion

Gaussian approximation


non-Gaussian interference

performance estimation

man-made noise


emission requirements

micro-wave oven


coding gain



10.00 HC1, Hörsalsvägen 14, Chalmers
Opponent: Dr. Yasushi Matsumoto, National Institute of Information and Communications Technology (NICT, Tokyo, Japan


Kia Wiklundh

Chalmers, Signaler och system, Kommunikation, Antenner och Optiska Nätverk





Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 2590

10.00 HC1, Hörsalsvägen 14, Chalmers

Opponent: Dr. Yasushi Matsumoto, National Institute of Information and Communications Technology (NICT, Tokyo, Japan

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