A novel method to determine the performance degradation of co-located frequency-hopping systems

In practical applications, frequency-hopping (FH) systems using different independent hopping patterns can be co-located close together. Even if the different FH systems use the same frequency band, the use of independent hopping patterns reduces the impact of intersystem interference. However, it is important to determine the performance degradation due to intersystem interference in the early design stage of such applications. If this is not done, any interference problems in the final application can be very difficult and expensive to handle. A method for such analyses has been developed where both the desired signals and the undesired spurious emissions are considered. With this method the bit error probability (BEP) for the co-located radio systems is estimated by use of the complete transmitted frequency spectrum of the radio systems. The method has been validated through measurements on real co-location situations for the Swedish army combat radio, the Ra 180. The analysis method is justified by the tight agreement between theoretical and experimental results. The results from this validation are presented, as well as a comparison with a simpler method where only the desired signal is considered. It is shown that for small co-location distances, the BEP for the co-located radio receiver will be seriously underestimated if other emissions than the desired output are neglected. Furthermore, three examples of applications of the method in radio design issues are shown