Patrik Eliardsson

Architectures for cognitive radio testbeds and demonstrators — An overview

Wireless communication standards are developed at an ever-increasing rate of pace, and significant amounts of effort is put into research for new communication methods and concepts. On the physical layer, such topics include MIMO, cooperative communication, and error control coding, whereas research on the medium access layer includes link control, network topology, and cognitive radio. At the same time, implementations are moving from traditional fixed hardware architectures towards software, allowing more efficient development. Today, field-programmable gate arrays (FPGAs) and regular desktop computers are fast enough to handle complete baseband processing chains, and there are several platforms, both open-source and commercial, providing such solutions. The aims of this paper is to give an overview of five of the available platforms and their characteristics, and compare the features and performance measures of the different systems.

Electromagnetic environment mapping for the assessment of critical wireless services in ISM bands

Wireless technologies for critical societal functions is becoming more common today. Criminals have already recognized this vulnerability and used it in various types of crimes. Unintentional radiated electromagnetic interference can also be a big problem for these types of services. Before deployment of critical societal functions based on wireless technologies, mapping and analysis of the electromagnetic environment area is essential. In this work a cost efficient system for qualified mapping and analysis of the electromagnetic environment is described and demonstrated. The example results herein presents a methodology to identify areas with increase background interference. Furthermore, an example of a system that operates in an unlicensed ISM-band is given and based on the mapping data, its vulnerability to other transmitters is analyzed and qualified.

Military HF communications considering unintentional platform-generated electromagnetic interference

High Frequency (HF) communications are of vital importance for modern military operations. It has the potential to move voice and data communications around the world by bouncing signals off the ionosphere, and at a fraction of the cost of heavily burdened satellite communication frequencies. However, HF-channels are touchy, unpredictable and prone to noise, fading, jamming and interference. Therefore, a number of prediction tools for channel selection have been developed. However, existing tools do not consider the local actual electromagnetic interference at receivers located on navy and army platforms. In this paper we propose a method to include this local electromagnetic interference in the frequency selection and we show how this method can improve the communication performance significantly. We also show that the consideration of local interference in combination with new wideband HF applications creates new challenges for power allocation and we show that the common water-filling solution is not always optimal with respect to data capacity in the system.

Power Control in Interference Channels With Class A Impulse Noise

In this letter, we consider optimal power allocation, with respect to sum capacity, for an interference channel affected by additive independent Class A impulse noise. The probability distribution of the sum of a Gaussian and a Class A distributed variable is derived, and the result is exploited to derive the sum capacity of an interference channel with independent Class A distributed impulse noise. Moreover, we show that the optimal power allocation strategy for the Class A interference channel can differ significantly from the solution to the commonly used additive white Gaussian noise interference channel.

Mitigation of multiple impulse noise sources through selective attenuation

On modern military platforms, there are many electronic systems that can cause interference to other. In order to mitigate the performance degradation this cosite interference might cause, attenuation of the received power from the interference sources is needed. In this work, we propose simple methods to select appropriate attenuation values for multiple impulse noise sources. The methods are based on approximations of the total bit error probability (BEP), in order to determine the impact from each individual source on the total system performance. Different methods for approximating the resulting BEP, and thereafter selecting the appropriate attenuations, are proposed based on different levels of knowledge of the individual interference signals. Either the BEP as a function of receive SIR or the impulsiveness correction factors (ICFs) and average powers are assumed to be known for each individual interference signal. The proposed methods are evaluated numerically and perform well in different scenarios.

Mitigation of co-channel interference by transmit power control

Interference in the vicinity of a receiving radio system can cause serious degradation of the radio communication performance. This may even result in disruptions and lost calls. For a co-location scenario of several communication systems, the combination of output powers will affect the total Signal-to-Noise Ratio (SNR) for receivers involved. In this paper, we show the dependence between output power, antenna coupling, out-of-band characteristics and communication distance. We present results of how these parameters can be combined to guarantee that necessary interference requirements in terms of SNR are met. Furthermore, it is shown that under certain conditions, the maximum achievable SNR only depends on the physical geometry of the co-location scenario.