The Study Of Viterbi Algorithm In Digital Trunking System

Trunking communication system is a private mobile communication system, which is used for commanding and dispatching, with resource sharing, communication channels sharing, efficient methods of wireless control and many other advantages. To ensure the reliable transmission of voice and data, the channel encoding method which the digital trunking communication system uses is CRC (circle redundant code) & RCPC (rate-compatible punctured convolution code) &interleave. In channel decoding, CRC and interleave are reversible in mathematics. The decoding of RCPC is using Viterbi decoding after filling the deleted bits'position with zero.Viterbi algorithm has been widely used in data transmission systems since it brings out in 1967, because of its high efficiency, fast speed, simply structure. Generally the structure of traditional Viterbi algorithm is complex, occupying a bit more parts of the resource in the hardware. Therefore, how to optimize design and reduce their complexity and loss is directly related to the size and function hall and performance of system hardware.Based on the (3,1,5) convolution code in digital trunking system, this paper first studied the decoding depth of the convolution code and fund out the right decoding depth for digital trunking system, then proposed a modified Viterbi decoding algorithm. This algorithm improved performance by united-decision estimating according to the relations of several groups near data. In the condition of equal decoding performance, the modified algorithm can reduce size and power consumption.The whole paper had been divided into four parts: the first part introduces the general situation of digital trunking system and its channel encoding, the recent development of Viterbi decoding; the second part studies the error control scheme, and the convolution decoding depth which is most fit to digital trunking system; the third part introduces several low power Viterbi decoder and its principle; the last part proposes a united-decision estimating Viterbi decoding algorithm. Based on the study of channel encoding scheme of digital trunking system, through the theoretic...