灵活大容量的OFDM-PON若干关键技术研究

发布时间：2018-12-27 12:02

【摘要】：随着用户对带宽接入需求的不断增长,光接入网步入了快速发展的阶段。接入网正向着更高速率、更长距离、带宽分配更灵活、业务类型更多样化的方向发展。以正交频分复用无源光网络(OFDM-PON)为代表的新型接入网技术引起越来越多的关注。OFDM-PON拥有较强的抗色散能力,频谱效率更高,带宽分配更灵活,扩展性和兼容性更强等优点,因此具有重要的研究价值。然而,OFDM-PON仍存在一些关键问题有待解决。例如：光OFDM信号发送与接收技术相对复杂因而成本较高；OFDM信号存在较大的峰均功率比(PAPR),直接调制激光器(DML)的调制效率较低；接入带宽的进一步提高受到数模转换模块(DAC/ADC)的采样率限制；时频域的带宽资源二维动态带宽分配(DBA)方案尚不完善,等等。围绕上述技术难题,论文对OFDM-PON中上行调制、直接检测(DD)下的偏振复用(PDM).时域与频域的带宽资源二维DBA等技术方案展开了研究。论文的主要研究工作和创新点如下： 1).为了提高OFDM-波分复用(WDM)-PON的波长自适应能力,设计了一种反射型半导体激光放大器(RSOA)与OFDM调制相结合的无色ONU方案。仿真结果表明,在传输距离为40km,误码率(BER)小于等于10-6量级时,基于RSOA的无色ONU上行带宽可从2.5Gbit/s提高到10Gbit/s。 2). OFDM信号具有较高的PAPR,要求激光器线性区间较大,且ONU的总能耗占接入网能耗的比重较大。因此,提高调制效率和降低激光器的能耗是OFDM-PON的重要问题。针对上述问题,提出了一种将非对称截断光正交频分复用(ACO-OFDM)与ONU激光器无数据关闭机制相结合的上行节能调制方案。该方案具有以下两个特点：(1)利用偏置在阈值点的DML在光域产生ACO-OFDM信号,降低了电路实现信号的难度与成本；(2)无上行数据时,激光器处于关闭状态,降低激光器能耗。仿真结果表明,与传统OFDM-PON调制方式相比,该方案可降低激光器发射功率,增大调制深度。在传输距离为20kmm,传输速率为10Gbit/s, BER为3.8×10-3(前向编码纠错FEC门限值)时,可节省发送功率约4.3dB。 3).针对OFDM-PON接入带宽受限于DAC/ADC采样率,提出了一种双边带(DSB)-PDM-DD-OFDM-PON无保护间隔下行调制方案。仿真结果表明,该方案无需信号与载波的保护间隔,在调制格式为16Q AM的情况下,下行链路仅用采样率为10GSa/s的DAC/ADC,即可使接入带宽到达40Gbit/s量级,辅以数字信道均衡后,在传输距离为20km时,BER小于3.8×10-3(FEC门限值)。 4).为了提高OFDM-PON带宽利用率,提出了一种基于业务流水线轮询(SPP)的时频域二维DBA算法。该算法解决了将TDM-PON算法直接搬用到OFDM-PON造成的资源分配粒度较大、存在信道空闲时间等问题。仿真结果表明,与OFDM-PON现有的顺序动态子载波分配(SDSCA)算法和自适应周期性间插轮询(IPACT) DBA相比,该算法可减小带宽碎片和时延,在满负载无丢包下,提高带宽利用率5%和7%。
[Abstract]:With the increasing demand for bandwidth access, optical access network has entered the stage of rapid development. Access networks are moving towards higher rates, longer distances, more flexible bandwidth allocation, and more diversified service types. New access network technology, represented by orthogonal Frequency Division Multiplexing (OFDM-PON) passive Optical Network (OFDM-PON), has attracted more and more attention. OFDM-PON has strong anti-dispersion capability, higher spectral efficiency and more flexible bandwidth allocation. The expansibility and compatibility are stronger and so on, so it has important research value. However, there are still some key problems to be solved in OFDM-PON. For example, the technology of transmitting and receiving optical OFDM signal is relatively complex and the cost is high, the modulation efficiency of (PAPR), direct modulation laser (DML) is lower than that of (PAPR), direct modulation laser because of the large peak-to-average power of OFDM signal. The further improvement of access bandwidth is limited by the sampling rate of digital-to-analog conversion module (DAC/ADC), and the two-dimensional dynamic bandwidth allocation (DBA) scheme in time-frequency domain is not perfect, and so on. According to the above technical difficulties, this paper directly detects the polarization multiplexing (PDM). In OFDM-PON by uplink modulation. Two-dimensional DBA of bandwidth resources in time domain and frequency domain are studied. The main research work and innovation are as follows: 1). In order to improve the wavelength adaptation of OFDM- wavelength division multiplexing (WDM) PON, a colorless ONU scheme combining (RSOA) with OFDM modulation is designed. Simulation results show that the uplink bandwidth of colorless ONU based on RSOA can be increased from 2.5Gbit/s to 10Gbit / s when the transmission distance is 40km and the bit error rate (BER) is less than 10-6. 2) The high PAPR, of OFDM signals requires a large linear range of lasers, and the total energy consumption of ONU accounts for a large proportion of the access network energy consumption. Therefore, improving modulation efficiency and reducing laser energy consumption are important problems in OFDM-PON. In order to solve the above problems, an uplink energy saving modulation scheme combining asymmetric truncated optical orthogonal frequency division multiplexing (ACO-OFDM) with a data-free switching mechanism for ONU lasers is proposed. The scheme has the following two characteristics: (1) the ACO-OFDM signal is generated in the optical domain by using the biased DML at the threshold point, which reduces the difficulty and the cost of realizing the signal in the circuit; (2) when there is no uplink data, the laser is closed and the energy consumption is reduced. The simulation results show that the scheme can reduce the laser power and increase the modulation depth compared with the traditional OFDM-PON modulation method. When the transmission distance is 20 kmm, the transmission rate is 10 Gbit / s and the BER is 3.8 脳 10 ~ (-3) (forward coding error correction FEC threshold), the transmission power can be saved about 4.3 dB. 3) Considering that the bandwidth of OFDM-PON access is limited by the sampling rate of DAC/ADC, an unprotected downlink modulation scheme with (DSB)-PDM-DD-OFDM-PON is proposed. The simulation results show that the scheme does not need the protection interval between signal and carrier. In the case of 16Q AM modulation format, the access bandwidth can reach the 40Gbit/s level in the downlink only by DAC/ADC, with a sampling rate of 10GSa/s. After digital channel equalization, when the transmission distance is 20km, the BER is less than 3.8 脳 10-3 (FEC threshold). 4) In order to improve the bandwidth utilization of OFDM-PON, a two-dimensional DBA algorithm in time and frequency domain based on traffic pipeline polling (SPP) is proposed. The algorithm solves the problem of large granularity of resource allocation and channel idle time caused by TDM-PON algorithm moving directly to OFDM-PON. The simulation results show that compared with the existing sequential dynamic subcarrier allocation (SDSCA) algorithm of OFDM-PON and adaptive periodic interleaved polling (IPACT) DBA), the proposed algorithm can reduce bandwidth fragmentation and delay without packet dropping. Increase bandwidth utilization by 5% and 7%.
【学位授予单位】：北京邮电大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN929.1

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