基于微波光子学的光纤无线电-无源光网络融合系统的研究进展

Research Progress of Converged Radio Over Fiber-Passive Optical Network System Based on Microwave Photonics

伴随着移动通信和多媒体业务的飞速发展,下一代接入网络的带宽需求呈现出了爆炸式增长的趋势。作为光接入网络的关键技术,无源光网络(PON)提供了巨大的带宽资源和长距离链路,但其灵活性受光纤铺设的严重限制。而光纤无线电(RoF)技术能够结合无线接入和光纤通信,发挥低损耗、高带宽的技术优势,促进两者的融合和发展。因此RoF技术与PON融合,能够充分利用光纤提供的巨大带宽和无线通信的灵活接入,更好地产生、处理和传输有线信号和微波信号,满足人们对多业务的需求。本文回顾了近几年的RoF-PON融合系统和关键技术,概述了微波信号的光子产生技术、RoF系统和下一代PON技术(NG-PON2)。此外,重点讨论和验证了RoF技术与波分复用PON(WDM-PON)、时分/波分复用PON(TWDM-PON)与正交频分复用PON(OFDM-PON)三种PON的融合方案。在经过20 km光纤传输后,所提的四通道RoF-WDM-PON和RoF-TWDM-PON的系统传输容量均为10 Gbit/s,误码率低至10-9。而RoF-OFDMWDM-PON系统可以实现下行50 Gbit/s的系统容量、50 km的光纤传输以及无源光网络单元(ONU)。最后,从系统的传输距离和误码率等方面对比分析了三种系统的可行性和优缺点。因此,基于微波光子学的RoF-PON融合系统不仅能够降低系统成本,提供高带宽和多业务服务,而且能够有效提升未来接入网络的容量和链路质量。

With the rapid development of mobile communication and multimedia services,the bandwidth demand for the next generation access network demonstrates an explosive growth trend.The passive optical network(PON)is a key technology of optical access that provides huge bandwidth resources and long-distance links,but its flexibility is severely limited by optical fiber laying.However,the radio over fiber(RoF)technology can combine wireless access and optical fiber communication to benefit from low loss and high bandwidth,and thus,promote the integration and development of the two.Therefore,making full use of the huge bandwidth provided by optical fiber and the flexible access of wireless communication,the integration of RoF technology and PON can better generate,process,and transmit wired signals and microwave signals to meet people’s needs for multi-services.This paper reviews the subsystems and key technologies of converged RoF-PON in recent years.The photon generation technology of microwave signal,RoF system,and next generation-PON(NG-PON2)are also summarized.Furthermore,the paper emphasizes the converged schemes of RoF technology and wavelength division multiplexing-PON(WDM-PON),time/wavelength division multiplexing-PON(TWDM-PON),and orthogonal frequency division-PON(OFDM-PON).The proposed four-channel RoF-WDM-PON and RoF-TWDM-PON system transmission capacity after 20 km of optical fiber transmission is 10 Gbit/s,with a bit error rate of 10-9.The RoF-WDM-OFDM-PON can realize a downstream system capacity of 50 Gbit/s,50 km of optical fiber transmission,and passive optical network unit(ONU).Finally,the feasibility,advantages,and disadvantages of these systems are compared and analyzed in terms of transmission distance and bit error rate.In a nutshell,the converged RoFPON system based on microwave photonics can not only reduce the system cost and provide high bandwidth and multiservices but also effectively improve the capacity and link quality of future access networks.