Interference analysis in the GSM-system

In the planning phase of a cellular radio network information on the expected radio interference between cells is needed many times. A new approach to the prediction of radio interference in GSM is introduced. Instead of concerning the carrier to interferer ratio C/I, often used in planning analog systems, an adequate algorithm for planning digital systems is presented. Including the fading statistics of the mobile radio channel, the algorithm calculates the probability that a digital quality threshold in terms of bit error rate (BER) is exceeded. The benefits of discontinuous transmission (DTX) in GSM to interference reduction is studied. Furthermore the impact of a partly traffic loaded interferer cell on interference is analysed. As a result of the analysis the use of DTX and a traffic load factor of e.g. 75% can reduce interference down to 63%.<
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