The Architecture And Performance Study Of Optical Burst Switching

The trends in optical communication network are introduced. The background and the inevitability of the coming forth of optical burst switching technology are presented. The architecture and the key technology of the optical burst switching are discussed.The default of traditional output schedule algorithm of the latest available unscheduled channel(LAUC) in OBS is given. In the traditional LAUC algorithm the effective window of packet loss vs unit delay time of fiber delay lines is very sharp. And the packet loss is increased greatly under delay reservation protocol. The reason the default produced is analyzed and a new latest available unscheduled channel with smallest void(LAUC-SV) algorithm is presented. The performance of the two algorithms is simulated. The results show that in LAUC-SV algorithm the effective window of the packet loss versus unit delay time of fiber delay lines is expanded significantly and the packet loss ratio is decreased about 100.5. The algorithm complexity of the LAUC-SV is only increased arithmetically with LAUC. Both the algorithms can not support delay reservation protocol effectively.The bursty characteristics in the output port doesn't exist almost when traditional bursty traffic goes through large scale switching with the probability of 1/N independently(N is the port number of the switch). In this paper a bursty assignment model under this case is presented. With this model the performance of the switching and the output schedule algorithm of latest available unscheduled channel with void filling(LAUC-VF) in OBS is simulated and compared with traditional model. This model presents a new method to analysis the performance of OBS under more badly conditions.The performance of switching architecture with multiple port shared is analyzed under nonbursty and bursty traffic model. The results show that the packet loss under bursty traffic model is much higher than nonbursty traffic. The packet loss under bursty and nonbursty traffic model is 10-8 and 10-15 separately when the number of the shared ports is 8, the fan-out number is 4 and the input traffic ratio is 0.8.The impact of the number of tunable wavelength converter in the switching architecture with shared tunable wavelength converter is analyzed. The results show that the packet loss is 10-1 higher without wavelength converter. And the packet loss goes down to 10-9 and 10-6 separately when the wavelength converter number are 1/3 and 1/4 of the total port number of the switching.The packet loss of the LAUC-VF algorithm under nonbursty and bursty traffic is simulated. The packet loss of the LAUC-VF algorithm under nonbursty and bursty traffic versus the the number of fiber delay lines, the unit delay time of fiber delay lines, the bursty traffic intensity, the bursty period are presented. The results show that the packet loss decreases significantly with the increase of the number of fiber delay lines. When the unit delay time of fiber delay lines D is less than 6 us the increase of D can significantly decrease the packet loss. But when D is larger than 6 us the packet loss decreases smoothly with the increase of D. The packet loss goes up with the increase of the bursty intensity. When the bursty period T1 is less than 4 times of the burst assemble time Ta the packet loss increases quickly with the increase of the bursty period. And when T1>4Ta the packet loss increases slowly with the increase of the bursty period.