Modeling competition - optical transport network modeling and value evaluation

1、 Content abstract

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370- Can communicate 、 consulting 、 Answering question

2、 Content description

Optical fiber Communication is the use of light as Information carrier 、 With Optical fiber As a transmission medium Of New communication mode . Optical transport network yes A number based Optical fiber communication Technical figures Communication network . Compare with Conventional microwave signal communication , Optical fiber communication With communication Large capacity 、 Long relay distance 、 Electromagnetic resistance The ability to interfere is strong 、 Confidentiality is good. 、 Rich in resources and easy to lay etc. characteristic . because Unique communication advantages of optical fiber communication , Optical transport network has been developing rapidly since its birth To promote the The rapid development of the whole communication field , The planning and construction of optical transmission network has become a further advance information technology innovation An important topic . among High reliability and high effect Optical transport network Network planning and construction Key content .

First , Due to the transmission loss of the transmission medium 、 Channel noise and other interference It's noisy influence , must not avoid Will cause Numbers In the communication system Transmit information appear error . Modulation and demodulation technology yes promote Digital communications A type of system reliability Important method . stay Numbers In optical fiber communication system , It has high resistance to noise Ability and comparison high Spectrum utilization Of M-ary Phase modulation and M-ary Amplitude phase joint modulation Become Main modulation methods . Ben The text is divided into Research QPSK、8QAM as well as 16QAM Three Modulation mode . according to Given in the title Modulation scheme construction Digital optical fiber communication system Simulation Model , Simulation calculation Get three different modulation The way Of Bit error performance curve as well as The bit error rate is 0.02 when Signal to noise ratio tolerance of ,QPSK Modulation mode ,BER=0.02 The SNR tolerance of is 8db;8QAM Modulation mode ,BER=0.02 The SNR tolerance of is 11.2db;16QAM Modulation mode ,BER=0.02 The SNR tolerance of is 14.2db. This part The main involve Communication simulation model establish And the problem of mathematical solution . Compared with multi-level phase modulation ,MQAM Modulation breaks the limitation that constellation points are located on the same circumference . Constellation points are evenly distributed on the signal plane , The minimum signal distance is processed by the principle of maximization , The anti-interference performance of the digital communication system is obviously improved . because Light transmission send link from Many are the same Span Cascade , take Maximum transfer distance Of The calculation model is equivalent to Maximum Span number solve The mathematical model of . Through mathematical iterative calculation, the single span transmission distance is 80km and 100km Optical transmission link at QPSK Maximum communication distance under modulation mode 38400km and 48100km, stay 8QAM Maximum communication distance under modulation mode 9120km and 11400km, stay 16QAM Maximum communication distance under modulation mode 2640km and 3300km.

Second, the second question, the first question , The connection matrix between cities is established , Its value is 0（ There is no link in the city ） perhaps 1（ Cities have links ）, For only 16 In the case of a link , The objective function and limit conditions are established , The maximum network value obtained by genetic algorithm is 1826300 wTb/s. stay 16 When the city links are determined, add 17 Links , The constraints of the optimization model have been updated , At this time, every city is no longer required to be connected to the network , Because this condition is in 16 The link model has been satisfied , At this point, the maximum network value of the whole system is 3652600wTb/s.

Last , In a typical star shape 16QAM And rectangular 16QAM The constellation structure is the prototype , According to the main rule of maximizing the minimum Euclidean distance , Arbitrarily change 16QAM Position of constellation points in the scheme 、 Number or probability of each point , Exploration produces several superior 8QAM Modulation scheme . Build a digital optical fiber communication system model , Through the comparison of BER performance curves corresponding to different modulation modes, it is determined that one with lower SNR Of the tolerance point 8QAM Modulation scheme . It turns out that ,8QAM Rectangle has the best bit error performance ,8QAM The star shape is the worst , Then the constellation modulation scheme with maximum and minimum Euclidean distance is optimal .

3、 Simulation analysis

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4、 Reference paper

[1] be based on Matlab Become QPSK The simulation of , Houzhouguo , Qianshengyou , Journal of Guangxi Normal University （ Natural science edition ）,March 2005 21-24

[2] https://map.baidu.com/

[3] Constellation based 8QAM Optimal structure selection

[4] https://www.mathworks.com/help/gads/ga.html#d120e46268

[5] Xuan Guangnan , Chengrunwei . Genetic algorithm and engineering optimization [M]. Tsinghua University Press Co., Ltd , 2004.