The Ethemet passive optical network （EPON） is the next generation of broad-band network technique. A crucial issue in EPONs is the sharing of uplink bandwidth among optical network units （ONUs）. This article provi...The Ethemet passive optical network （EPON） is the next generation of broad-band network technique. A crucial issue in EPONs is the sharing of uplink bandwidth among optical network units （ONUs）. This article provides a novel dynamic bandwidth allocation algorithm, i.e. threshold dynamic bandwidth allocation （TDBA）, which is based on adaptive threshold, to increase resource utilization. The algorithm uses ONU data-transmitting rate to adjust optical line terminal （OLT） receiving data threshold from an ONU. Simulation results show that this algorithm can decrease average packet delay and increase network throughput in a l 0G EPON system.展开更多
A passive optical network （PON） scheme based on optical code division multiplexing （OCDM） for the downstream traffics is proposed and analyzed in detail. In the PON, the downstream traffics are broadcasted by OCDM...A passive optical network （PON） scheme based on optical code division multiplexing （OCDM） for the downstream traffics is proposed and analyzed in detail. In the PON, the downstream traffics are broadcasted by OCDM technology to guarantee the security, while the upstream traffics pass through the same optical fiber by the common time division multiple access （TDMA） technology to decrease the cost. This schemes are denoted as OCDM/TDMA-PON, which can be applied to an optical access network （OAN） with full services on demand, such as Internet protocol, video on demand, tele-presence and high quality audio. The proposed OCDM/TDMA-PON scheme combines advantages of PON, TDMA, and OCDM technology. Simulation results indicate that the designed scheme improves the OAN performance, and enhances flexibility and scalability of the system.展开更多
An optical network is a type of data communication network built with optical fibre technology. It utilizes optical fibre cables as the primary communication medium for converting data and passing data as light pulses...An optical network is a type of data communication network built with optical fibre technology. It utilizes optical fibre cables as the primary communication medium for converting data and passing data as light pulses between sender and receiver nodes. The major issue in optical networking is disjoints that occur in the network. A polynomial time algorithm Wavelength Division Multiplexing-Passive Optical Networking (WDM-PON) computes disjoints of an optical network and reduces the count of disjoints that occur in the network by separating Optical Network Units (ONU) into several virtual point-to-point connections. The Arrayed Waveguide Grating (AWG) filter is included in WDM-PON to avoid the traffic in the network thereby increasing the bandwidth capacity. In case of a failure or disjoint Ant Colony Optimization (ACO) algorithm is used to find the optimized shortest path for re-routing. For enhanced security, modified Rivert Shamir Adleman (RSA) algorithm encrypts the message during communication between the nodes. The efficiency is found to be improved in terms of delay in packet delivery, longer optical reach, optimized shortest path, packet error rate.展开更多
In order to realize broadband and high-speed transmission in the last mile access network,the Coded Wavelength-Division Multiplexing(Coded-WDM)technique on PON(so-called CDM-PON)is presented on fiber-to-the-home acces...In order to realize broadband and high-speed transmission in the last mile access network,the Coded Wavelength-Division Multiplexing(Coded-WDM)technique on PON(so-called CDM-PON)is presented on fiber-to-the-home access network.In this paper,the codcd-WDM coder/decoder(codec}is configured on Optical Network Unit(ONU)and Optical Line Terminal(OLT)in Ethemet Passive Optical Network(E-PON).Here,network codecs are constructed with Arrayed Waveguide Grating(AWG)devices and the signature address code is employed as complementary Walsh code whose original code is for data bit'1'and complementary code is for data bit'0'respectively.It is shown that the simultaneous active user of proposed scheme using CWH code is improved 100%than using M-Sequence and conventional Walsh code for given bit error rate of 10^-9.In addition,the signal to noise ratio(SNR)performance is improved by 6dB compared with conventional scheme employed M-sequence and Walsh code.展开更多
Coherent passive optical network(PON)is a promising architecture that offers high sensitivity and support for advanced modulation formats.However,fully coherent systems have high complexity and cost,making them unsuit...Coherent passive optical network(PON)is a promising architecture that offers high sensitivity and support for advanced modulation formats.However,fully coherent systems have high complexity and cost,making them unsuitable for cost-sensitive user-end applications.Additionally,in coherent access architectures,the lasers of optical network units(ONUs)in the upstream are typically kept on rather than being switched off to avoid wavelength drift,with the Mach–Zehnder modulators(MZMs)biased at the null point for modulation.However,the limited extinction ratio(ER)of the MZM introduces direct current(DC)leakage,which degrades system performance and limits the number of users the network can support.To address this issue,we design and fabricate the first silicon-photonics-based ultimate-simplified coherent-optics chip for ONU.The simplified transmitter employs a single MZM combined with a high-speed optical switch(OS),while the simplified receiver adopts a hybrid and a standalone photodetector(PD)for coherent detection with Alamouti coding.By integrating the OS,the upstream achieves a maximum ER of 63.93 d B,while the OS switching speed meets the guard interval requirements of PON systems.Compared to a traditional single MZM with a 26 d B ER,our design achieves an additional 37.93 d B improvement,which significantly increases the user capacity in PON systems.Comprehensive experiments were conducted to validate the proposed design.Ultimately,leveraging this ultimate-simplified coherent-optics chip,a 100 Gbps bidirectional transmission was successfully demonstrated with a power budget exceeding 29 d Bm,verifying its feasibility and cost-effectiveness for next-generation coherent optical access networks.展开更多
Next-generation passive optical networks(PONs)demand power conservation to create a green environment.A reduction in power consumption of the traditional Ethernet passive optical network(EPON)can be achieved by increa...Next-generation passive optical networks(PONs)demand power conservation to create a green environment.A reduction in power consumption of the traditional Ethernet passive optical network(EPON)can be achieved by increasing the sleep count in optical network units(ONUs).In this paper,this is accomplished by introducing a first-in-last-out(FILO)polling sequence in the place of a fixed polling sequence to increase the number of ONUs entering sleep mode(sleep count).In a fixed polling sequence,the optical line terminal(OLT)allocates idle time to the ONUs based on the overall load of the ONUs.This leads to a situation that whenever the idle time does not meet the wakeup time threshold of sleep mode,the ONUs are put into doze/active mode,which consumes more power.In the FILO polling sequence,the first polled ONU in the current cycle is made to be polled last in the following cycle.Polling continues in this way,and by this rearrangement,the idle time of delayed poll ONUs increases;hence,it helps to reduce the power consumption.Additionally,a modified load adaptive sequence arrangement(MLASA)method is suggested,where the ONUs are categorized into doze ONUs and sleep ONUs.A numerical simulation of the FILO polling sequence with a vertical cavity surface emitting laser(VCSEL)ONU shows a maximum reduction in power consumption of 15.5 W and a 20%improvement in energy savings compared with the traditional fixed polling sequence.The MLASA method results in better power consumption with minimum delay than that of the proposed FILO and existing LASA methods.展开更多
A simple and cost-effective remodulation scheme using a two-section reflective semiconductor optical amplifier （RSOA） is proposed for a colorless optical network unit （ONU）. Under proper injection currents, the fr...A simple and cost-effective remodulation scheme using a two-section reflective semiconductor optical amplifier （RSOA） is proposed for a colorless optical network unit （ONU）. Under proper injection currents, the front section functions as a modulator to upload the upstream signal while the rear section serves as a data eraser for efficient suppression of the downstream data. The dependences of the upstream transmission performance on the lengths and driven currents of the RSOA, the injection optical power and extinction ratio of the downstream are investigated. By optimizing these parameters, the downstream data can be more completely suppressed and the upstream transmission performance can be greatly improved.展开更多
文摘The Ethemet passive optical network （EPON） is the next generation of broad-band network technique. A crucial issue in EPONs is the sharing of uplink bandwidth among optical network units （ONUs）. This article provides a novel dynamic bandwidth allocation algorithm, i.e. threshold dynamic bandwidth allocation （TDBA）, which is based on adaptive threshold, to increase resource utilization. The algorithm uses ONU data-transmitting rate to adjust optical line terminal （OLT） receiving data threshold from an ONU. Simulation results show that this algorithm can decrease average packet delay and increase network throughput in a l 0G EPON system.
文摘A passive optical network （PON） scheme based on optical code division multiplexing （OCDM） for the downstream traffics is proposed and analyzed in detail. In the PON, the downstream traffics are broadcasted by OCDM technology to guarantee the security, while the upstream traffics pass through the same optical fiber by the common time division multiple access （TDMA） technology to decrease the cost. This schemes are denoted as OCDM/TDMA-PON, which can be applied to an optical access network （OAN） with full services on demand, such as Internet protocol, video on demand, tele-presence and high quality audio. The proposed OCDM/TDMA-PON scheme combines advantages of PON, TDMA, and OCDM technology. Simulation results indicate that the designed scheme improves the OAN performance, and enhances flexibility and scalability of the system.
文摘An optical network is a type of data communication network built with optical fibre technology. It utilizes optical fibre cables as the primary communication medium for converting data and passing data as light pulses between sender and receiver nodes. The major issue in optical networking is disjoints that occur in the network. A polynomial time algorithm Wavelength Division Multiplexing-Passive Optical Networking (WDM-PON) computes disjoints of an optical network and reduces the count of disjoints that occur in the network by separating Optical Network Units (ONU) into several virtual point-to-point connections. The Arrayed Waveguide Grating (AWG) filter is included in WDM-PON to avoid the traffic in the network thereby increasing the bandwidth capacity. In case of a failure or disjoint Ant Colony Optimization (ACO) algorithm is used to find the optimized shortest path for re-routing. For enhanced security, modified Rivert Shamir Adleman (RSA) algorithm encrypts the message during communication between the nodes. The efficiency is found to be improved in terms of delay in packet delivery, longer optical reach, optimized shortest path, packet error rate.
文摘In order to realize broadband and high-speed transmission in the last mile access network,the Coded Wavelength-Division Multiplexing(Coded-WDM)technique on PON(so-called CDM-PON)is presented on fiber-to-the-home access network.In this paper,the codcd-WDM coder/decoder(codec}is configured on Optical Network Unit(ONU)and Optical Line Terminal(OLT)in Ethemet Passive Optical Network(E-PON).Here,network codecs are constructed with Arrayed Waveguide Grating(AWG)devices and the signature address code is employed as complementary Walsh code whose original code is for data bit'1'and complementary code is for data bit'0'respectively.It is shown that the simultaneous active user of proposed scheme using CWH code is improved 100%than using M-Sequence and conventional Walsh code for given bit error rate of 10^-9.In addition,the signal to noise ratio(SNR)performance is improved by 6dB compared with conventional scheme employed M-sequence and Walsh code.
基金National Key Research and Development Program of China(2023YFB2905700)National Natural Science Foundation of China(62171137,62235005)Natural Science Foundation of Shanghai Municipality(24ZR1490500)。
文摘Coherent passive optical network(PON)is a promising architecture that offers high sensitivity and support for advanced modulation formats.However,fully coherent systems have high complexity and cost,making them unsuitable for cost-sensitive user-end applications.Additionally,in coherent access architectures,the lasers of optical network units(ONUs)in the upstream are typically kept on rather than being switched off to avoid wavelength drift,with the Mach–Zehnder modulators(MZMs)biased at the null point for modulation.However,the limited extinction ratio(ER)of the MZM introduces direct current(DC)leakage,which degrades system performance and limits the number of users the network can support.To address this issue,we design and fabricate the first silicon-photonics-based ultimate-simplified coherent-optics chip for ONU.The simplified transmitter employs a single MZM combined with a high-speed optical switch(OS),while the simplified receiver adopts a hybrid and a standalone photodetector(PD)for coherent detection with Alamouti coding.By integrating the OS,the upstream achieves a maximum ER of 63.93 d B,while the OS switching speed meets the guard interval requirements of PON systems.Compared to a traditional single MZM with a 26 d B ER,our design achieves an additional 37.93 d B improvement,which significantly increases the user capacity in PON systems.Comprehensive experiments were conducted to validate the proposed design.Ultimately,leveraging this ultimate-simplified coherent-optics chip,a 100 Gbps bidirectional transmission was successfully demonstrated with a power budget exceeding 29 d Bm,verifying its feasibility and cost-effectiveness for next-generation coherent optical access networks.
文摘Next-generation passive optical networks(PONs)demand power conservation to create a green environment.A reduction in power consumption of the traditional Ethernet passive optical network(EPON)can be achieved by increasing the sleep count in optical network units(ONUs).In this paper,this is accomplished by introducing a first-in-last-out(FILO)polling sequence in the place of a fixed polling sequence to increase the number of ONUs entering sleep mode(sleep count).In a fixed polling sequence,the optical line terminal(OLT)allocates idle time to the ONUs based on the overall load of the ONUs.This leads to a situation that whenever the idle time does not meet the wakeup time threshold of sleep mode,the ONUs are put into doze/active mode,which consumes more power.In the FILO polling sequence,the first polled ONU in the current cycle is made to be polled last in the following cycle.Polling continues in this way,and by this rearrangement,the idle time of delayed poll ONUs increases;hence,it helps to reduce the power consumption.Additionally,a modified load adaptive sequence arrangement(MLASA)method is suggested,where the ONUs are categorized into doze ONUs and sleep ONUs.A numerical simulation of the FILO polling sequence with a vertical cavity surface emitting laser(VCSEL)ONU shows a maximum reduction in power consumption of 15.5 W and a 20%improvement in energy savings compared with the traditional fixed polling sequence.The MLASA method results in better power consumption with minimum delay than that of the proposed FILO and existing LASA methods.
基金supported by the National High Technology Research and Development Program of China(No.2013A014401)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20120142110064)
文摘A simple and cost-effective remodulation scheme using a two-section reflective semiconductor optical amplifier （RSOA） is proposed for a colorless optical network unit （ONU）. Under proper injection currents, the front section functions as a modulator to upload the upstream signal while the rear section serves as a data eraser for efficient suppression of the downstream data. The dependences of the upstream transmission performance on the lengths and driven currents of the RSOA, the injection optical power and extinction ratio of the downstream are investigated. By optimizing these parameters, the downstream data can be more completely suppressed and the upstream transmission performance can be greatly improved.
