Loss of pointer in SDH digital radio relay systems

The use of synchronous digital hierarchy (SDH) in digital radio relay systems (DRRS) requires the analysis of the effect of error statistics on the transmission frame. In fact, due to the recent adoption in high capacity SDH DRRSs of transmission techniques such as low redundancy error-correcting codes, trellis coded modulations, Viterbi receivers, etc., the errors produced in the presence of noise tend to be clustered in bursts. The occurrence in the SDH transmission systems of error bursts may cause severe malfunctioning, such as, for example, the loss of a virtual container due to the incorrect detection of a pointer. In order to evaluate the loss of pointer probability due to errors, as defined in CCITT Rec. G.709 and G.783, it is necessary to know the error distribution in a time interval of N bits. The paper first describes the new model adopted to represent the error distribution and the probability to have an incorrect detection of a pointer. Then, the results obtained by means of a such new model are presented and compared with those obtained by both simulation and measurements, using the above-mentioned transmission techniques. Finally, the characteristics of the simulated transmission system and measurement set-up are described