Multiuser Detection for WDM Long-Haul Fiber-Optic Communication Systems

WDM 长距离光纤通信系统的多用户检测

• 批准号: 0311198
• 负责人: Maite Brandt-Pearce
• 金额: $ 31.8万
• 依托单位: University of Virginia Main Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-15 至 2006-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0311198&HistoricalAwards=false
• 关键词: Multiuser; Detection; WDM; Long; Haul

Fiber-optic links have the potential of terabit per second transmission. Long-haul links, such as transoceanic and transcontinental data-trunks, have demonstrated a need for such high data throughput. System designers are able to provide the high data throughput using a technique known as dense wavelength division multiplexing (WDM), where multiple lower rate signals are combined unto a single fiber by using several wavelengths of light. Long-haul WDMfiber channels are performance limited by linear dispersion and nonlinear crosstalk. The nonlinear effects create a correlation between the signals received at different wavelength channels. In this research multiuser detection schemes to exploit this dependence and jointly demodulate multiple channels are developed. Multiuser detection has attracted enormous attention in RF multiuser communications in the last twenty years. They are powerful at combating the harmful effects of interference from other users in the system. In so doing they allow the channel capacity per user toincrease from that possible in single-user communications. The same advantages are suspected to persist in applying these detectors to WDM fiber systems. Many aspects of the physical model of the fiber system differ from the RF model. Because of the fiber nonlinearities and the photodetector processing, the interference and dominant noise are signal dependent, giving a very different statistical description of the received signal. Moreover, the modulation and the signal detection act only on the intensity of the signal, prohibiting the use of the signal phase at either end.Therefore, multiuser detectors developed for RF communications cannot be used directly for the fiber problem.In this research, optimal and suboptimal detectors such as maximum likelihood, linear, quadratic, and decision feedback detectors are designed to suit fiber-optic systems. Special attention is placed on the hardware requirements of each design to ensure that it can be implemented at 10 or even 40 gigabits per second, as required for these types of systems. A system of small simultaneous detectors over small groups of adjacent channels allows the most significant nonlinear crosstalk to be cancelled without requiring a prohibitive computational complexity. Detectors must alsooperate on data with very coarse resolution. The performance of these detectors can be measured using variants of minimum distance, bounds on the error probability, calculations of the asymptotic multiuser efficiency, and simulation. By using these techniques, system designers will be able to increase the span length between fiber amplifiers to more than the 100 km currently possible, increase the channel density by decreasing the channel spacing to below the current20 GHz limit, and improve the quality of service of each channel to below an error-rate of 10- 12 .

光纤链路具有每秒太比特传输的潜力。长途链路，如跨洋和跨洲的数据干线，证明了对如此高的数据吞吐量的需求。系统设计人员能够使用一种称为密集波分复用(WDM)的技术来提供高数据吞吐量，在该技术中，通过使用多个波长的光将多个较低速率的信号组合到一根光纤中。长距离WDM光纤信道的性能受到线性色散和非线性串扰的限制。非线性效应在不同波长信道上接收的信号之间产生相关性。在这项研究中，开发了利用这种相关性并联合解调多个信道的多用户检测方案。在过去的二十年里，多用户检测在射频多用户通信中引起了极大的关注。它们在对抗来自系统中其他用户的干扰的有害影响方面非常强大。在这样做时，它们允许每个用户的信道容量在单用户通信中可能的基础上增加。人们怀疑，将这些检测器应用于WDM光纤系统具有相同的优势。光纤系统的物理模型的许多方面不同于RF模型。由于光纤的非线性和光电探测器的处理，干扰和主要噪声依赖于信号，给出了对接收信号非常不同的统计描述。此外，调制和信号检测只作用于信号的强度，禁止在任何一端使用信号相位。因此，为射频通信开发的多用户检测器不能直接用于光纤问题。在本研究中，最优和次最优检测器如最大似然检测器、线性检测器、二次检测器和判决反馈检测器被设计成适合光纤系统。要特别注意每种设计的硬件要求，以确保能够按照这些类型的系统的要求以每秒10或甚至40千兆位的速度实施。在一小群相邻信道上的小型同时检测器的系统允许在不需要令人望而却步的计算复杂性的情况下消除最显著的非线性串扰。探测器还必须对分辨率非常低的数据进行操作。这些检测器的性能可以使用最小距离的变量、差错概率的界、渐近多用户效率的计算和仿真来测量。通过使用这些技术，系统设计人员将能够将光纤放大器之间的跨度长度增加到超过目前可能的100千米，通过将信道间隔降低到当前的20 GHz限制来增加信道密度，并将每个信道的服务质量提高到10-12以下的误码率。