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
A direct detection optical orthogonal frequency division multiplexing(DDO-OFDM)system using turbo codes is built,and the transmission performance comparison between coded system and uncoded system is analyzed.Three de...A direct detection optical orthogonal frequency division multiplexing(DDO-OFDM)system using turbo codes is built,and the transmission performance comparison between coded system and uncoded system is analyzed.Three decoding algorithms,which are Log-maximum a posteriori(MAP),Max-Log-MAP and threshold Max-Log-MAP,are used in the turbo coded system.By comparing three decoding algorithms,the system using Max-Log-MAP algorithm has the best bit error rate(BER)performance.At the transmission distance of 240 km,the uncoded system with transmission rate of 30 Gbit/s can get the BER performance at the degree of 8.93×10-3 with optical signal to noise ratio(OSNR)of24 d B,while the turbo coded system with transmission rate of 50 Gbit/s can achieve it within OSNR of 20 d B.展开更多
A novel architecture of wavelength-division multiplexing/optical code division multiplexing access-passive optical network （WDM/OCDMA-PON） based on superstructure fiber Bragg grating （SSFBG） and wavelength re-modu...A novel architecture of wavelength-division multiplexing/optical code division multiplexing access-passive optical network （WDM/OCDMA-PON） based on superstructure fiber Bragg grating （SSFBG） and wavelength re-modulation technology is proposed. In this scheme, WDM is overlaid on OCDMA channel in a single network by virtue of a kind of SSFBC, and the total capacity of hybrid PON can be extended by regulating the transmission power reasonably. Re, modulation technology is also a good method to save wavelength-specific components at the optical network unit （ONU） and cost of wavelength management on the customer side. In simulation system, 1.25 Gb/s up/downstream data are transported with good performance. In addition the crosstalk penalties from adjacent wavelength channels （with the same OC） are found to be negligible in upstream and downstream transmissions.展开更多
All optical network based on wavelength division multiplexing transmission system with optical cross connect (OXC) is an essential approach for optical commumications.Crosstalk introduced by OXC (specially large scale...All optical network based on wavelength division multiplexing transmission system with optical cross connect (OXC) is an essential approach for optical commumications.Crosstalk introduced by OXC (specially large scale one) is a key limiting factor for its capacity. Optical signal passing through a typical OXC is analyzed in this paper, followed by description of the generation and effect of intraband crosstalk.The power penalties induced by intraband crosstalk versus the number of multiplexed wavelengths M and the number of input fibers N have been given by numerical simulations. The results show that the coherent crosstalk is the most critical limitation on OXC and depends more closely on the number of multiplexed wavelengths M than the number of input fibers N . Crosstalk is suppressed by doubly filtering, fixing optimum decision-threshold and appropriately choosing the number of multiplexed wavelengths M .展开更多
With the increasing requirements of the multicast services in the whole data traffic service, the optical multicast technology becomes a key technology supporting wide bandwidth and high speed multicasting communicati...With the increasing requirements of the multicast services in the whole data traffic service, the optical multicast technology becomes a key technology supporting wide bandwidth and high speed multicasting communication. The transmission efficiency, capacity and robustness of optical multicast network can be further improved by introducing network coding technology into optical multicast networks. Meanwhile, facing to demand of emerging rate-variable multi-granularity multicast service, a multi-path transmission scheme based on network coding for routing and spectrum allocation (RSA) is proposed. It can not only allocate spectrum resources effectively and flexibly for various-rate multicast traffic, but also balance the network load, improve network throughput and reduce transmission blocking rate. In this paper, RSA problem is decomposed into two subproblems, namely routing allocation based on network coding and spectrum allocation based on maximum spectrum first (MSF) strategy, which are solved sequentially. Simulation experiments are carried out to analyze transmission performance with proposed RSA scheme. The simulation results show that the proposed RSA mechanism can allocate spectrum resources efficiently and flexibly for multi-granularity multicast traffic. Compared with RSA schemes based on shortest path tree (SPT) and minimal spanning tree (MST), the proposed RSA scheme is more efficient for spectrum resource utilization and load balancing, and spectrum resource is saved more than 20%.展开更多
A hybrid wavelength division multiple access （WDMA）/optical code division multiplexing （OCDM） system is proposed, where the optical code is not the same as the address of every optical network unit （ONU）; rather...A hybrid wavelength division multiple access （WDMA）/optical code division multiplexing （OCDM） system is proposed, where the optical code is not the same as the address of every optical network unit （ONU）; rather, the code is a virtual fiber of hybrid passive optical network （PON）. To our knowledge, this is the first report analyzing a single encoder/decoder with a single corresponding optical code being exploited to encode/decode multiple wavelength signals simultaneously. This system enables OCDM to become transparent to ONU so that the existing wavelength division multiplexing （WDM） PON can be upgraded. Thus, redesigning the optical line terminal and ONU can be easily accomplished, and greatly decreasing the number of encoder/decoder becomes possible. In experiment, we only employ two encoder/decoder pairs to combine two WDM-PONs in one fiber. Simulation results confirm the feasibility of the proposed system.展开更多
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.
基金supported by the National Natural Science Foundation of China(No.61107052)the Tianjin Natural Science Foundation of China(No.11JCYBJC0010)the Tianjin Youth Foundation of China(No.13JCQNJC01800)
文摘A direct detection optical orthogonal frequency division multiplexing(DDO-OFDM)system using turbo codes is built,and the transmission performance comparison between coded system and uncoded system is analyzed.Three decoding algorithms,which are Log-maximum a posteriori(MAP),Max-Log-MAP and threshold Max-Log-MAP,are used in the turbo coded system.By comparing three decoding algorithms,the system using Max-Log-MAP algorithm has the best bit error rate(BER)performance.At the transmission distance of 240 km,the uncoded system with transmission rate of 30 Gbit/s can get the BER performance at the degree of 8.93×10-3 with optical signal to noise ratio(OSNR)of24 d B,while the turbo coded system with transmission rate of 50 Gbit/s can achieve it within OSNR of 20 d B.
基金Project supported by the Shanghai Leading Academic Discipline Project (Grant No.S30108)the Science and Technology Commission of Shanghai Municipality (Grant No.08DZ2231100)
文摘A novel architecture of wavelength-division multiplexing/optical code division multiplexing access-passive optical network （WDM/OCDMA-PON） based on superstructure fiber Bragg grating （SSFBG） and wavelength re-modulation technology is proposed. In this scheme, WDM is overlaid on OCDMA channel in a single network by virtue of a kind of SSFBC, and the total capacity of hybrid PON can be extended by regulating the transmission power reasonably. Re, modulation technology is also a good method to save wavelength-specific components at the optical network unit （ONU） and cost of wavelength management on the customer side. In simulation system, 1.25 Gb/s up/downstream data are transported with good performance. In addition the crosstalk penalties from adjacent wavelength channels （with the same OC） are found to be negligible in upstream and downstream transmissions.
文摘All optical network based on wavelength division multiplexing transmission system with optical cross connect (OXC) is an essential approach for optical commumications.Crosstalk introduced by OXC (specially large scale one) is a key limiting factor for its capacity. Optical signal passing through a typical OXC is analyzed in this paper, followed by description of the generation and effect of intraband crosstalk.The power penalties induced by intraband crosstalk versus the number of multiplexed wavelengths M and the number of input fibers N have been given by numerical simulations. The results show that the coherent crosstalk is the most critical limitation on OXC and depends more closely on the number of multiplexed wavelengths M than the number of input fibers N . Crosstalk is suppressed by doubly filtering, fixing optimum decision-threshold and appropriately choosing the number of multiplexed wavelengths M .
文摘With the increasing requirements of the multicast services in the whole data traffic service, the optical multicast technology becomes a key technology supporting wide bandwidth and high speed multicasting communication. The transmission efficiency, capacity and robustness of optical multicast network can be further improved by introducing network coding technology into optical multicast networks. Meanwhile, facing to demand of emerging rate-variable multi-granularity multicast service, a multi-path transmission scheme based on network coding for routing and spectrum allocation (RSA) is proposed. It can not only allocate spectrum resources effectively and flexibly for various-rate multicast traffic, but also balance the network load, improve network throughput and reduce transmission blocking rate. In this paper, RSA problem is decomposed into two subproblems, namely routing allocation based on network coding and spectrum allocation based on maximum spectrum first (MSF) strategy, which are solved sequentially. Simulation experiments are carried out to analyze transmission performance with proposed RSA scheme. The simulation results show that the proposed RSA mechanism can allocate spectrum resources efficiently and flexibly for multi-granularity multicast traffic. Compared with RSA schemes based on shortest path tree (SPT) and minimal spanning tree (MST), the proposed RSA scheme is more efficient for spectrum resource utilization and load balancing, and spectrum resource is saved more than 20%.
基金supported by the National Natural Science Fundation of China(Nos.60972032 and 60632010)the National"863"Project of China(Nos. 2006AA01Z251 and 2007AA01Z271)
文摘A hybrid wavelength division multiple access （WDMA）/optical code division multiplexing （OCDM） system is proposed, where the optical code is not the same as the address of every optical network unit （ONU）; rather, the code is a virtual fiber of hybrid passive optical network （PON）. To our knowledge, this is the first report analyzing a single encoder/decoder with a single corresponding optical code being exploited to encode/decode multiple wavelength signals simultaneously. This system enables OCDM to become transparent to ONU so that the existing wavelength division multiplexing （WDM） PON can be upgraded. Thus, redesigning the optical line terminal and ONU can be easily accomplished, and greatly decreasing the number of encoder/decoder becomes possible. In experiment, we only employ two encoder/decoder pairs to combine two WDM-PONs in one fiber. Simulation results confirm the feasibility of the proposed system.
