In this paper a novel optical burst assembly technique, namely path loss rate driven burst assembly which is an enhancement on an adaptive threshold based burst assembly is proposed. Path loss rate driven burst assembly adjusts the threshold values based on the feedback obtained from the network. Each egress node sends feedback packets periodically to each ingress node informing them on the contention level along the path. As the traffic along the corresponding path becomes lighter, an ingress node allows the corresponding burst generator to use greater time and size threshold values. Conversely, under heavy traffic along the path, the corresponding burst generators are forced to decrease the time and size threshold parameters. The results are obtained in terms of byte loss rate and delay, and compared with those obtained under nonadaptive (static) burst assembly and previously proposed link loss rate based adaptive threshold burst assembly. It is observed that the proposed technique significantly decreases the byte loss rate as the traffic gets heavier by keeping the end to end delay in a feasible range.