Yu Wenbin, Chen Fei, Xu Zeyu, Zhang Yifan, Liu Alex X, Zhang Chengjun
Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology (CICAEET), Nanjing University of Information Science and Technology, Nanjing 210044, China.
School of Computer Science, Nanjing University of Information Science and Technology, Nanjing 210044, China.
Entropy (Basel). 2022 Jul 29;24(8):1044. doi: 10.3390/e24081044.
In this paper, we propose a novel multi-user access in wireless optical communication based on the quantum detection of the coherent state. In this case, the coherent states are used as the signal carrier and a technique of quantum detection is applied to distinguish between signals from different users. To accomplish this task, two main quantum measurement methods are introduced; one is minimum error discrimination (MED), and the other is unambiguous state discrimination (USD). The theoretical derivation implies that the two methods can both distinguish between the signals from different users efficiently when the average photon number is large enough. Typically, the numerical result shows that in the two-user case, the channel capacity will approach the theoretical maximum limit when the average photon number is greater than 2.5 for MED and 5 for USD in the absence of noise. The MED gains more channel capacity than the USD at the same average photon number. However, the USD wins the error-correction scene with its free-error capability. Furthermore, the detection error probability and channel capacity for the USD with the thermal noise are examined. The result shows that increasing the signal average photon number can continue the USD's advantage of error-free detection even if in the presence of thermal noise. In addition, compared with non-orthogonal multiple access (NOMA), the bit error rate (BER) against signal-to-noise rate (SNR) performance of USD has been improved.
在本文中，我们基于相干态的量子检测提出了一种新颖的无线光通信多用户接入方案。在这种情况下，相干态被用作信号载体，并且应用量子检测技术来区分来自不同用户的信号。为完成此任务，引入了两种主要的量子测量方法；一种是最小错误判别（MED），另一种是无误状态判别（USD）。理论推导表明，当平均光子数足够大时，这两种方法都能有效地区分来自不同用户的信号。通常，数值结果表明，在两用户情况下，在无噪声时，对于MED，当平均光子数大于2.5，对于USD，当平均光子数大于5时，信道容量将接近理论最大极限。在相同平均光子数下，MED比USD获得更多的信道容量。然而，USD凭借其无误能力在纠错场景中胜出。此外，还研究了存在热噪声时USD的检测错误概率和信道容量。结果表明，即使存在热噪声，增加信号平均光子数也能延续USD无误检测的优势。此外，与非正交多址接入（NOMA）相比，USD的误码率（BER）相对于信噪比（SNR）的性能得到了改善。
