基于Laguerre模型的光子计数无线光通信系统研究

发布时间：2018-09-10 09:22

【摘要】：无线光通信即自由空间光(Free-Space Optical, FSO)通信,因其具有高带宽、抗干扰、高数据传输率等特点,越来越受到国内外的重视,是无线通信领域研究的重要方向之一。FSO虽然有很多优点,但也存在诸多影响FSO通信性能的因素,比如大气湍流,背景噪声,热噪声等,因此本文首先阐述了FSO通信的原理和关键技术,针对自由空间光通信系统中光子计数技术,研究通信过程中各类噪声、干扰的影响,综合考虑热辐射、背景辐射及大气湍流的影响并进行系统建模,推导了基于Laguerre模型采用开关键控(On-Off Keying, OOK)调制以及脉冲位置调制(Pulse Position Modulation, PPM)时在不同大气湍流模型下的误码率(Bit Error Rate, BER)计算方式,并通过计算机蒙特卡洛仿真验证了所提出算法的正确性,通过仿真结果表明大气湍流和噪声是影响自由空间光通信性能的主要因素。之后本文提出通过空间分集技术来调高系统性能,并分别推导了基于Laguerre模型采用发射分集、接收分集以及多输入多输出技术(Multiple-Input Multiple-Output, MIMO)系统在强大气湍流下的误码率表达式,通过仿真评估了空间分集对系统性能的改进效果。此外,本文还研究了基于Laguerre模型的交织分多址(Interleave-Di vision Multiple-Access, IDMA)多用户系统的迭代检测技术,提出基于最优贝叶斯(Optimum Bayesian, OB)算法的多用户检测(Multiuser Detection, MUD)方案。通过计算机仿真,测试系统在不同环境下的性能,仿真结果表明IDMA技术可以有效削弱多用户干扰(Multiple Access Interference, MAI),而OB算法可加快系统检测收敛速度,提升系统性能。
[Abstract]:Wireless optical communication, known as free space optical (Free-Space Optical, FSO) communication, has attracted more and more attention at home and abroad because of its high bandwidth, anti-jamming and high data transmission rate, although it has many advantages in the field of wireless communication. However, there are many factors that affect the performance of FSO communication, such as atmospheric turbulence, background noise, thermal noise and so on. Therefore, the principle and key technology of FSO communication are first expounded in this paper, aiming at photon counting technology in free space optical communication system. The effects of various kinds of noise and interference in the communication process are studied. The effects of thermal radiation, background radiation and atmospheric turbulence are considered and the system model is established. Based on the Laguerre model, the (Bit Error Rate, BER) calculation method of bit error rate (BER) under different atmospheric turbulence models using open key control (On-Off Keying, OOK) modulation and pulse position modulation (Pulse Position Modulation, PPM) is derived. The correctness of the proposed algorithm is verified by computer Monte Carlo simulation. The simulation results show that atmospheric turbulence and noise are the main factors affecting the performance of optical communication in free space. After that, this paper proposes to improve the performance of the system by spatial diversity, and derives the BER expressions based on Laguerre model using transmit diversity, receiving diversity and multiple input and multiple output (Multiple-Input Multiple-Output, MIMO) systems under strong gas turbulence. The improvement effect of spatial diversity on system performance is evaluated by simulation. In addition, this paper also studies the iterative detection technology of interleaved division multiple access (Interleave-Di vision Multiple-Access, IDMA) multiuser systems based on Laguerre model, and proposes a multiuser detection (Multiuser Detection, MUD) scheme based on the optimal Bayesian (Optimum Bayesian, OB) algorithm. Through computer simulation, the performance of the system in different environments is tested. The simulation results show that the IDMA technology can effectively weaken the multi-user interference (Multiple Access Interference, MAI), while the OB algorithm can accelerate the convergence speed of the system detection and improve the system performance.
【学位授予单位】：复旦大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.1

【共引文献】