Golay Code / Convolutional Codes Applied Research In The Digital Trunking System

With the transition to 3G of the cellular mobile communication, the trunked system is converting from analog technology to digital technology. As a special mobile system, the trunked system is not entirely the same as the cellular mobile system even if it inherits many advantages of the cellular communications. The purpose of this thesis is to accomplish encoding and decoding of the extened Golay code and the 1/2 convolutional code with Xilinx FPGA applicable in the trunked system.FPGA has been largely used in ditital communication systems.In the trunked system, (23,12) Golay code transfering signaling has a minimum distance of seven,so it has very strong error-correcting capability . The syndrome-decoding algorithm is adopted for the extened golay code. Because of occupying excessive memory in FPGA, the error-pattern table has to place not in FPGA but external memory. We encode and decode extened golay code with FPGA and test connected with PC. The voice data has been transmited with covolutional code that Viterbi decoded algorithm is adopted. In terms of the module design principle,the (2,1,2) parallel decoding porcess is composed of eight function modules.But the design performance is very weak and the maximum clock frequency is very low.The pipeline technology and other optimizing step are applied in the design. Contrasting with Xilinx Viterbi IP Core,we achieved the results of 63.103MH maximum frequency and 205 logic Slices.Because of overabundance data exchange of the (2,1,6) code, the block RAM must be used. For the tradeoff of resource saving and enhancing speeds, a parallel- series decoding structure is adoped.Accoding to this structure, the results of 44.064 MHz maximum frequency and 1428 slices are achieved.