Research On High-efficiency MC-CDMA Technology Under The Background Of Underwater Acoustic Communication

The underwater acoustic channel is a time-frequency extension channel with limited bandwidth.It is currently recognized as one of the most complex communication channels.It has the characteristics of serious multipath effects,large Doppler shifts,and large fading.It requires more other communication technologies combined with improving the performance of underwater acoustic communication.According to the channel characteristics of underwater acoustic communication,this paper aims to improve the transmission efficiency and reliability of underwater acoustic MC-CDMA communication technology,and proposes an efficient underwater acoustic MC-CDMA communication model,and improves the efficiency and speed of synchronization acquisition,and reduces the solution.Adjust the bit error rate of the algorithm,and carry out the research on the key technology of high-efficiency underwater MCCDMA communication.The high-efficiency underwater acoustic MC-CDMA communication model proposed in this paper has the advantages of anti-Rayleigh fading characteristics of underwater acoustic MC-CDMA communication and higher transmission efficiency,and has good application prospects in the field of military and civil underwater communication.The main research work of this article:1.According to the characteristics of the underwater acoustic channel,after comparative analysis,based on MC-DS-CDMA,combined with parallel combined spread spectrum communication technology,an underwater acoustic parallel combined MC-CDMA communication system with higher transmission efficiency is proposed,which improves the transmission efficiency of underwater acoustic MC-CDMA communication technology;proposes an underwater acoustic parallel combined MC-CDMA communication system with the least transmitted sequence,which effectively reduces the number of transmission sequences and bandwidth,saves transmitter power,and reduces the system error rate.The simulation shows that the underwater acoustic parallel combination MC-CDMA communication system has higher reliability,lower bit error rate,and has good anti-multipath interference characteristics.2.Aiming at the common MC-CDMA communication synchronization acquisition algorithm that does not take into account the characteristics of the spreading sequence,a new joint rapid acquisition algorithm based on dual cyclic prefix and fixed spreading sequence is proposed,which can greatly reduce the amount of calculations and multipliers that synchronization acquisition needs and reduce the complexity of acquisition circuit and make the full use of the M correlator groups in the receiver and improve the acquisition speed and performance.Simulation analysis shows that the acquisition performance is improved.Improved the new fast acquisition algorithm based on pilot header and data parallel transmission,which can greatly reduce the amount of acquisition calculations.Under the condition of large signal-to-noise ratio,the acquisition system based on pilot header and data parallel transmission is better and has better Stability,reliability.3.By analyzing the regular pattern distribution of possible errors in the sequence of the receiving end of the system,the system can reduce the bit error rate when the mapping relationship is not greatly reduced.This paper proposes a demodulation algorithm based on the iterative method,which effectively overcomes the change of the hard threshold is affected by the receiving end signal-to-noise ratio,and the sending sequence is determined by the iterative soft decision of the receiving end.Theoretical analysis and simulation results show that while ensuring the efficiency of information transmission,the iterative method has lower bit error rate performance.In this dissertation,a new parallel combined underwater acoustic MC-CDMA communication model is proposed to improve the reliability of communication transmission,reduce the system error rate,and have better suppression characteristics for multi-path spread interference.The model and algorithm proposed above is analyzed and verified by computer simulation,and the effectiveness of the model and algorithm is verified.