In optical burst switching networks, a larger value of the offset time (the time duration between the burst assembly finishing time and the transmission time of the burst) is desirable to decrease packet loss rate. However, a larger offset value introduces a longer delay at edge routers because packet arriving during the offset time are not assembled into the current burst in conventional methods. In this paper, we consider a strategy where a larger offset time is used and packets arriving during the offset time are assembled into the current burst. In order to attain the policy, we propose two methods A and B. In the method A, we estimate the amount of packets arriving duration the offset time and we reserve wavelength channels so that the packets can be transmitted by the current burst. The method A however has a weak point that the reserved time is partly useless when the estimated amount is too large. In order to resolve it, the method B again estimates the amount of arrived packets halfway through the offset time and releases the redundant reserved time when the second estimated amount is less that the first one. Numerical examples shows the effectiveness of the proposed methods, and the method B is superior to the method A when the packet arrival process is the Pareto ON-OFF process.
