Study Of Adaptive Measurement Quantum Receivers In Laser Communication System

Due to the existence of scattered noise in the communication system,the performance of the receiver cannot break through the classical detection limit,which is called standard quantum limit(SQL).By using quantum receiver to detect coherent states,the performance of the receiver can exceed the SQL,obtaining lower error probability and higher channel capacity.Up to now,there have been many significant achievements and breakthroughs in quantum receiver theory and experiment.However,the quantum receivers in laser communication system can only approach the ultimate performance limit theoretically so far.In order to achieve practical application of quantum receiver in laser communication system,and break through the quantum limits of receiver performance in practice.We need to furtherly investigate the signal modulation mode and channel coding schemes,and the most important thing is to optimize the structure and control strategy of the quantum receiver to make it robust and achievable.In my academic dissertation,I will mainly investigate three theoretical parts in the following:1.Research on partitioned-interval adaptive measurement quantum receiver for phase shift keying(PSK)signals.The partitioned-interval adaptive measurement quantum receiver with optimal displacement which has been proposed lately does not take into account various non-ideal factors of the device.Therefore,we investigate the performance of this receiver under non-ideal conditions for PSK modulation signals in this paper.In addition,since the bit error rate performance of he partitioned-interval adaptive measurement quantum receiver is related to the partitioning strategy.So in this paper,we extends the global optimization method in both the receiver strategy and the modulation signal,and present a globally optimal partitioned-interval adaptive measurement quantum receiver which can be applied to high-order PSK modulation signals.2.Research on adaptive measurement quantum receiver for binary coding signals.The joint-detection quantum receiver can not only obtain the low bit error rate performance,but also achieve the superadditivity of channel capacity and thus approach the channel capacity limit.Based on the previous proposed joint-detection quantum receiver,we present an optimized adaptive measurement quantum receiver scheme in this paper.Besides,we applied this receiver to binary coding signals,and prove that the receiver provides the performance beating the SQL,and its superiority over the conditional pulse nulling(CPN)receiver in weak signal region is also demonstrated.3.Research on low-complexity adaptive measurement quantum receiver for pulse position modulation(PPM)and multi-pulse position modulation(MPPM)signals.PPM/MPPM signals are widely used due to its simple structure of modulation circuit and strong anti-interference ability in channels.Considering that when the state dimension of the detected signal of the optimal detection quantum receiver is high,the complexity of the dynamic programming algorithm is too high,which is prone to "dimensional disaster".In order to optimize the value of control variables to obtain superior performance and also prevent the occurrence of"dimensional disaster",we present a low-complexity detection scheme based on the maximum a posteriori(MAP)criterion in this paper.