自适应调制技术在OFDM-PON系统动态平衡带宽分配中的应用

发布时间：2018-06-22 17:56

本文选题：OFDM-PON + 动态带宽分配　；参考：《南京邮电大学》2017年硕士论文

【摘要】：随着PON系统的发展,正交频分复用无源光网络(OFDM-PON)凭借其高效率和灵活多变的优势,成为下一代接入网的主要研究内容之一。然而,怎样在大量的ONU之间有效地分配系统带宽成为OFDM-PON系统在实际部署前的重要问题之一。首先,本文对无源光网络的网络结构进行了介绍,探讨了OFDM技术的基本原理,并且对OFDM-PON中的相关关键技术进行了概括分析。其次,本文研究了基于OFDM-PON系统的动态带宽分配算法,探讨了自适应调制算法的发展历史和基本原理。在传统的时间、波长和功率的三维动态带宽分配模型的基础上,结合自适应调制技术,提出了一种基于四维动态带宽分配的自适应调制算法,并且将单个ONU的传输性能进行优化。其中比特加载算法根据各ONU比特率需求之比分配各子载波的调制格式,在子载波数一定情况下,对比特率要求高的ONU用更高阶的调制方式来实现,灵活的分配系统容量。功率加载算法用于根据各自采用的调制格式而产生的不同的信噪比,从而为各个ONU发射不同的功率。这样,即使各个ONU运行的比特率不同,也能有平衡的传输性能。在长短距离共存OFDM-PON系统中,由于用户之间地理位置的差异性,距离不同带来的时延是不可避免的。本文结合分组动态带宽分配(MG-DBA)算法将ONU根据距离不同进行分组,并且结合自适应调制算法优化了长距离ONU的OSNR,实现了不同ONU的比特率需求,实现了长距离OFDM-PON系统带宽的动态均衡分配。最后,本文利用OptiSystem 14软件设计了一个OFDM-PON传输系统验证了所提出的带宽分配模型以及自适应算法的可行性。
[Abstract]:With the development of PON system, orthogonal Frequency Division Multiplexing passive Optical Network (OFDM-PON) has become one of the main research contents of next generation access network because of its high efficiency and flexibility. However, how to allocate the bandwidth between a large number of ONUs effectively becomes one of the important problems before the actual deployment of OFDM-PON systems. Firstly, the network structure of passive optical network is introduced, the basic principle of OFDM technology is discussed, and the key technologies in OFDM-PON are analyzed. Secondly, the dynamic bandwidth allocation algorithm based on OFDM-PON system is studied, and the development history and basic principle of adaptive modulation algorithm are discussed. Based on the traditional 3D dynamic bandwidth allocation model of time, wavelength and power, an adaptive modulation algorithm based on four-dimensional dynamic bandwidth allocation is proposed. The transmission performance of a single ONU is optimized. The bit-loading algorithm allocates the modulation format of each subcarrier according to the ratio of each ONU bit rate requirement. In the case of a certain number of sub-carriers, the ONU with high bit rate requirements is implemented in a higher-order modulation mode, and the system capacity is allocated flexibly. The power loading algorithm is used to transmit different power for each ONU according to the different SNR generated by each modulation scheme. Thus, even if the bit rate of each ONU is different, it can achieve balanced transmission performance. In long-distance coexistence OFDM-PON systems, the delay caused by different distances is inevitable due to the difference of geographical location among users. In this paper, we combine packet dynamic bandwidth allocation (MG-DBA) algorithm to group ONU according to different distance, and combine with adaptive modulation algorithm to optimize OSNR of long distance ONU, and realize different bit rate requirement of ONU. The dynamic equalization allocation of long distance OFDM-PON system bandwidth is realized. Finally, an OFDM-PON transmission system is designed using OptiSystem14 software to verify the feasibility of the proposed bandwidth allocation model and adaptive algorithm.
【学位授予单位】：南京邮电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.1

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