Study On Key Technologies Of Optical Label Switching

With the explosive growth of Internet, various data services and multi-media services, it is required with much wider bandwidth of network, the larger transmission capability and the more rapid switching speed. Although the wavelength division multiplexing (WDM) technology can make full use of the huge bandwidth resource of optical fiber and enhance the transmission capacity and speed, the electrical switching is still the main technology in the switching node, and results in the mismatch between low processing speed of electrical components and the fast rate of transmission network, restricting the deeper development of communication. The optical switching will solve the electric bottleneck with the all-optical switching technologies, and support services with multi-granularity. However, the all-optical components are still in the laboratory phase. Therefore, the optical label switching (OLS) is proposed with a mixed optoelectronic structure and combined the advantage of electrical and optical technologies. OLS has been the focus in the optical switching research area.A great deal of domestic and foreign literatures have been analyzed and summarized in this paper, about the optical label schemes, optical label switching technologies and so on. Two main optical labeling techniques, orthogonal modulated optical labeled technique and optical code (OC) labeled technique, have been theoretically researched, and the parameters and the performance of the optical labeled system has been investigated by simulation. Besides, the label swapping and recognition have also been studies and some methods have been proposed in these respects. The main work and innovations are as follows: 1. Study on orthogonal modulated optical labeled technique based on frequency shift keying (FSK)(1) A novel scheme is proposed to generate the FSK signal with semiconductor optical amplifier (SOA), which has the advantage of simple architecture and integrating easily. Based on this scheme, the 40Gbit/s FSK/ASK optical labeled system is founded by simulation. The performance of this system is investigated, including the average power of laser, the extinction ratio (ER) of signal light in the FSK transmitter, the performance of whole system, and the ER of ASK payload. The results show that the FSK/ASK labeled system with the FSK label generated by cross gain modulation (XGM) has a promising transmission performance and receiver sensitivity.(2) A novel scheme is proposed to realize the FSK transmitter adopting the polarization shift keying (PolSK) modulation, with the advantages of transparence for data rate and the tuning of frequency spacing. Based on this FSK transmitter, the FSK/ASK orthogonal modulated labeled system is implemented, with 1.25Gbit/s FSK label and 40Gbit/s ASK payload. By simulation, the bit-rate ratio (BER) performance of ASK payload and FSK label in the case of back-to-back (B2B),60km and 96km optical fiber transmission are analyzed. Besides, the ER of ASK payload and frequency spacing of FSK label are investigated and the optimal values are chosen.(3) Inverse return-zero modulation method is adopted to solve the limitation of ER of ASK payload. The FSK/inverse return-to-zero (IRZ) orthogonal modulation labeled system based on the PolSK has been founded by simulation. Compared with the FSK/ASK labeled system at the same rate, the influence of the ER of IRZ payload has discussed in the FSK/IRZ labeled system. Moreover, the transmission performance of the FSK/IRZ labeled system with different duty ratio has also been analyzed in the B2B and 96km fiber transmission. The results have been presented that the IRZ modulation can enhance the ER of payload, and higher duty ratio of IRZ payload is helpful for the FSK label detection, but deteriorates the IRZ payload.2. Study on the orthogonal modulated labeled system with differential phase shift keying (DPSK) label and pulse position modulation (PPM) payload(1) PPM technique is induced to solve the ER limitation of payload in the DPSK/ASK optical labeled system. The 40Gbit/s DPSK/PPM optical labeled system has been founded by simulation. Compared with the DPSK/ASK labeled system at the same rate, the ER of PPM payload has been analyzed. Besides, the relationship between BER and received optical power of DPSK label and PPM payload after the transmission of B2B and 96km fiber has also been investigated. The PPM pulse width has been studied for the influence on the system performance. The results show that DPSK/PPM labeled signal has a potential transmission performance and the ER of payload has been improved with the PPM format.(2) A novel scheme of DPSK label erasure has been proposed using four wave mixing (FWM) in SOA for the DPSK/PPM labeled system. The scheme has been analyzed theoretically with the advantages of transparence for the data rate, fast processing speed and simple architecture. By the simulation, the 40Gbit/s DPSK/PPM labeled switching system has been performed with the 2.5Gbit/s and 10Gbit/s DPSK label. In the core node, the label erasure is realized by the FWM effect and the new DPSK label is inserted by phase re-modulation. The performance of PPM payload after the label erasure and the new DPSK label has been investigated. The results show that the label erasure scheme can implement the label erasure at different date rate of label.3. Study on spectrum amplitude code (SAC) labeled switching system(1) The SAC labeled switching system with time-stacked labels has been proposed, which has the flexible and simple architecture. Based on this optical label system with time-stacked labels, the FWM and fiber Bragg grating (FBG) has been adopted to realize the label recognition. This scheme has the advantages of fast processing speed, transparence for data rate, and avoiding the payload information lost when removing the leading label in the time-stacked labels.(2) The 40Gbit/s optical label switching system with two time-stacked SAC labels and two forwarding nodes has been founded by simulation. In the core node, The SAC labels are recognized by the FWM sidebands which are generated by the two wavelength in each the SAC label and the FBG with the fixed Bragg wavelength for each node. The performance of the two forwarding nodes has been investigated by analyzing the BER of the output for each node. The results show that the forwarding nodes have promising forwarding performance and prove the feasibility of SAC label recognition with FWM effect.