A new approach for considering the interference impact on digital radio systems from complex interference environments
Doctoral thesis, 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
emission
non-Gaussian interference
performance estimation
man-made noise
measurement
emission requirements
micro-wave oven
MSK
coding gain
APD
interference
10.00 HC1, Hörsalsvägen 14, Chalmers
Opponent: Dr. Yasushi Matsumoto, National Institute of Information and Communications Technology (NICT, Tokyo, Japan