| With the rapid development of modern communications technologies, with the great advantages of their own, digital communication has gradually replaced analogue communications, and in the field of wireless communications it has occupied a dominant position. In the communication system model, channel coding and modulation technology play a decisive role in the entire communication system, and become a hot research and theory of modern communications technology .In the field of wireless communications, characteristics of channel is more complex. With the growing demand of users of telecommunications of data transmission speed and quality, as well as the continuous improvement of visual communications business and the quality of services and diversified business requirements, new communications technologies continue to emerge. In these new technologies, the new channel coding program and decoding ideas a revolution to wireless communications.BICM-ID is designed to be used in the wireless communication channel coding methods. This is a combination of coding, modulation and iterative decoding technology. BICM-ID adopted the idea of combination of coding and modulation, firstly proposed by the TCM, and the application of the principle of iterative decoding of Turbo Codes. By adding bits in the interleave design and soft-input soft-output SISO decoder and using MAP or the combination of LOG-MAP method and iterative decoding idea, it improve the quality of decoding.In the characteristics of the wireless Channel, multi-path transmission will result in Rayleigh fading and frequency dispersion; frequency selectivity will also be weakened. Digital transmission needs relatively high digital signal transmission rate and the relatively high rate of the digital transmission requires a broader signal bandwidth .So, serious inter-symbol interference occur frequently because of the existence of selective fading phenomenon. In order to reduce inter-symbol interference, digital signal transmission rate is usually limited. The limitations of the Shannon formula are above.In the AWGN, diversity is not a major factor decoding performance, also play a major role in the dominant signal is the smallest Euclidean distance. Li and Ritcey, iterative decoding signals can improve BICM the Euclidean distance between the minimum, Hamming while maintaining expectations. Bit intertwined because of thefreedom of small random modulation causes Euclidean distance, the use of iterative decoding. Through carefully designed signal mapping, the indirect free Hamming distance can change at National Cheng free Euclidean distance.Knowledge is the basis for the three preceding chapters were part of the background on the subject on the basis of knowledge and communication. Three coding and related technology Chapter IV of the decoding algorithm and Labeling System constellation of methods for mapping analysis MAP V to the new improved algorithm and the analysis of the mapping rules. BICM-ID with the diversity of technology while integrating the attempt.In theory, BICM-ID System, the deeper the cutting depth of interleaver, the smaller the signal correlation, the stronger the capability of anti-burst error .This essay studies the relationship between the cutting depth of BICM-ID and the timely extension and the error rate of the system. The simulation results show the greater cutting depth, the smaller the error rate.The simulation results show that using feedback iterative soft-decision decoding, the performance of BICM-ID is over BICM and TCM. We are aware of the Diversity technology is a major technology of anti-diversity technology in the Rayleigh fading channels. So adding the interleaver and deinterleaver to BICM-ID transceiver ends, greatly enhances the performance of the anti-fading of BICM-ID, improving performance of BICM-ID in the Rayleigh fading channels. The simulation results show that BICM and BICM-ID performance better than TCM due to a bit interleaver. The idea of BICM-ID is a iterative decoding system, therefore, the number of iterations dealing with different decoding quality. Through the research of BICM-ID we can find that BICM-ID iterative process makes demodulator and decoder to transmit information between each other. As a result, the mutual message can benefit from each other; the ultimate realization of the firm's improved the performance of decoding. Based on the number of different decoding simulation to test the merits of iterative decoding. The simulation results show the iterative error rate of system was significantly lower than the error rate.BICM-ID the ideological successor of the TCM design signal mapping, Constellation type of error correction coding , interleaver and signal to the premise, 8-PSK signal mapping for a greater effect on the performance of BICM-ID System. Guidelines drawn to maximize coding gain equivalent to a constellation of space to maximize the Euclidean distance have no wrong feedback from the harmonic mean theory.In the view of the three existing mapping standards Gray, SP and SSP. Scientists have tried different mapping program expecting to get one or more better standards in theory. This paper studies SP, SSP and Gray mapping methods. Meanwhile, a new analysis of recent MSP Constellation mapping method has been found. The analysis concluded: although MSP constellation map get the same maximize Euclidean distance as SSP through the design, but because of its design, MSP sacrifices parts of mapping rules for the max Euclidean distance. So only when it is in a particular area of NSR can MSP be better than the three other traditional mapping methods .The conclusions have once again confirmed the rules of mapping.By designing signal mapping program ,BICM-ID system indirectly changes big Hamming distance to the free Euclidean distance, which improves the system performance in the AWGN channel; interleaver used in the technical aspect of a system realizes Diversity Reception ,enhances anti-jamming capability and reliability of the system; meanwhile, iterative decoding greatly approaches the Shannon Limit. The article also compares the MAP and revolved LOG-MAP algorithm and MAX-LOG-MAP. Simulation results show that the appropriate changes to the MAP algorithm, although reducing the amount of calculate and setting up the hardware with a convenient, it increases the system bit error rate. We can see that MAP decoding algorithm is the best one in theory.Finally, the article introduces frequency diversity, improving the performance of decoding. The results also prove the Effectiveness of diversity technology against wireless channel fading. Diversity has become a hot area and critical technologies of wireless communications.A ware of the advantages of the system performance, at the same time we should also recognize that the existing inadequate. Although in the theoretical simulation stage, BICM-ID is good, if as a single product, put this technology into the market, to business; it needs millions of experiments under the conditions of wireless communications. Whether It is as mature as the Turbo and can meet the requirements to improve the quality and diversity of communication, needs to get a conclusion from experiment and the test network in the global wireless communications market. In order to have a better future, BICM-ID should not only on the theoretical stage but also cooperate with advanced communications technology, such as the combination with smart antennas, with SDMA technologies, and multi-user detection technology, which are worthy of study and exploration. |
PDF Full Text Request