The Research On All-Optical Virtual Private Network And Wavelength Plan In Optical Access Networks

In optical access network (OAN), compared with active opticalnetwork (AON), passive optical network (PON) has many features, such ascompatibility with high-speed transmission, transparency to modulationformat and higher reliability. The advantages make PON become apromising candidate in future optical access areas, and make PON becomea hot research topic in both the academia and industry instead of OAN.Nowadays, APON, BPON, EPON and GPON have been put into practice.And the next-generation PONs, such as NG-PON1and NG-PON2, havebeen investigated and operated in the labs. Meanwhile, PONs, takingadvantages of all-optical virtual private network (VPN) which offersdedicated optical channels to connect optical network units (ONUs), cansupport fast communication services among ONUs, thus enablingguaranteed the bandwidth of data transmission between ONUs andenhanced security at the physical layer. The flexibility and concurrency ofVPN communications among ONUs are highly desirable in thenext-generation PON.In the thesis, we first investigate the generation approaches of16QAM. And then, we propose an orthogonal frequency division multipleaccess-based PON (OFDMA-PON) architecture supporting flexibleall-optical VPN with source-free ONUs, and a scheme of flexible andconcurrent all-optical VPN in OFDMA-PON. Finally, we focus on thewavelength plan of the next-generation PON. 1. Investigation of the generation approaches of16QAMCompared with amplitude shift keying (ASK) and phase-shiftingkeying (PSK), for16QAM modulation format a symbol carries4-bitmessages. As a result, with the same baud rate, the bit rate of16QAM datawould be four times of that of ASK or PSK data. PONs, taking advantagesof16QAM modulation format, can greatly improve the data capacity,while maintaining good transmission performance. Therefore,16QAM isthe commom modulation format in high-speed long-reach fibertransmission system. In addition, in the following chapters of this thesis,the signals in the experiments adopt16QAM format. We first investigatethe generation appraoches of16QAM, and we give the some generationschemes of star-16QAM, square-16QAM and16APSK.2. The flexibility and concurrency of all-optical VPNAll-optical VPN is a promising approach to offer dedicated opticalchannels to connect ONUs, which provides fast data communications forONUs. In the current schemes of all-optical VPN in PON systemsproposed by scholars at home and abroad, a laser is utilized to transmitVPN data in each ONU, which is not good for reducing the cost andenergy consumption of the optical access network. In addition, in thecurrent schemes published, each ONU can only transmit the same VPNdata to one or more ONUs at the same time, which can not meet the needof the next-generation dynamic optical networks. Here, we first generatethree-tone downlink signal employing dual-parallel Mach-Zehndermodulator (DPMZM) at the OLT. And then one sideband is separated fromthe downlink signal and reused for the uplink and VPN data at the ONUside, thus realizing all-optical VPN with source-free ONUs inOFDMA-PON. In addition, in this thesis, using orthogonal frequencydivision multiplexing (OFDM), we assign each ONU multiple subcarriersin a given time slot to carry different VPN data to other ONUs, thusrealizing the flexibility and concurrency of VPN communications inOFDMA-PON. 3. The wavelength plan of the next-generation PONThe current PON can not meet the increasing service demand ofONUs. Therefore, the next-generation PON system emerges as the timesrequire. NG-PON1includes symmetric10G GPON and asymmetric10GEPON. NG-PON2includes WDM-PON, TWDM-PON and OFDM-PON.When NG-PON1and NG-PON2are integrated into the current PONsystem, nonlinear effects, such as four wave mixing (FWM), stimulatedRaman scattering (SRS) and cross phase modulation (XPM), can not beneglected. In the coexistence system of GPON, VIDEO, NG-PON1andNG-PON2, these effects will degrade the system performance. In the thesis,with the software of VPI transmissionMaker Optical Systems, we simulatethe wavelength plan of the next-generation PON system to realize lowcrosstalk in the case of the integration of different networks, and error-freetransmission of high split-ratio PON system.