FIELD: radio engineering. SUBSTANCE: invention specifically refers to methods of data decoding in direct channel of project of UMTS-2000 standard for second type of intermittent transmission. Technique of data decoding in direct channel of UMTS-2000 for second type of intermittent transmission ( type II DTX ) consists in decoding of data of transport channel from point of start of frame to all possible points of termination of data block of frame to form decoded chains of data. Resolving value is formed per each chain of data. Minimum value from obtained resolving values is isolated and compared with threshold value. If minimum value is less than threshold value then cyclic control sum ( CRC ) for this chain of decoded data which corresponds to minimum resolving value is calculated. If cyclic control sum (CRC ) coincides then corresponding chain of decoded data is considered true. Novelty of technique lies in calculation of cyclic control sum per each chain of decoded data beginning from shortest chain. Independent of resolving value evaluation of probability of symbol error ( SER ) is formed by way of backward coding which is used as resolving value for comparison with threshold if cyclic control sum per decoded data block coincides. If evaluation of probability of symbol error is less than threshold then decision is made that given chain of decoded symbols is true and decoding of frame is stopped. Otherwise decoding is continued to next possible point of stop. When end of frame is reached and decision oncorrect chain of decoded data is not made yet then this decision is made on following conditions: if cyclic control sum coincides per one chain of decoded data only then it is considered true; if cyclic control sum coincides per k chains of decoded data, where k>1 ( any integral number ), then sum providing for minimum evaluation of probability of symbol error is considered true; if cyclic control sum did not coincide with single chain of decoded data then chain that provided for minimum evaluation of probability of symbol error ( SER ) is considered true. EFFECT: increased authenticity of data decoding. 4 dwg
