This letter proposes a new adaptive power management mechanism (APM2) which takes into account the remaining energy in an IEEE 802.16e system. Benefits of the mechanism are the reduction of frame response delay in a state with sufficient remaining energy, and an increase in the life of a station in a state of insufficient remaining energy. An analytical model for sleep mode operation is developed, and the proposed mechanism is validated by computer simulation.

Suitably aggregated data burst enhances link utilization and reduces data processing complexity of optical transport networks rather than just transmitting each bursty input traffic from access networks. This data burst generation method is called as a burst assembly process and has two assembly parameters, timer and threshold, for regulating burst release time and burst size. Since the traffic characteristics of data burst generated at the burst assembler may affect network performance, the decision of burst assembly parameters should be carefully designed. Thus, in this paper we study the dimensioning burst assembly process to find the burst assembly parameter values satisfying target performance. For this purpose, we first analyze timer-based and threshold-based burst assembly processes, respectively. As constraints on the dimensioning burst assembly process, we consider the following performance metrics: 1) processing delay of control packet, 2) burst loss at control plane, and 3) link utilization. Based on these constraints, a decision mechanism of the burst assembly parameters is proposed. From numerical analysis, we suggest a possible lower boundary value for the burst assembly parameters satisfying the target burst loss rate and delay time at the control plane.

In this paper, we develop an analytical model to evaluate the performance of optical burst switching (OBS) node with optical-level buffers for retransmission of blocked bursts. First, currently used burst blocking models and modelling of optical buffers at OBS nodes are shown to be inappropriate as a blocking model for retransmission in OBS nodes. Thus, we propose a new blocking model for the burst transmission mechanism with retransmission technique in an optical-level buffered OBS node. From the numerical analysis, we show the performance enhancement by applying optical buffers for retransmission of blocked bursts in terms of burst blocking probability and link utilization.

Optical Burst Switching (OBS) is one of the most promising switching technologies for next generation optical networks. As delay-sensitive applications such as Voice-over-IP (VoIP) have recently become popular, OBS networks should guarantee stringent Quality of Service (QoS) requirements for such applications. Thus, this paper proposes an Adaptive Loss-aware Flow Control (ALFC) scheme, which adaptively decides on the burst offset time based on loss-rate information delivered from core nodes for assigning a high priority to delay-sensitive application traffic. The proposed ALFC scheme also controls the upper-bounds of the factors inducing delay and jitter for guaranteeing the delay and jitter requirements of delay-sensitive application traffic. Moreover, a piggybacking method used in the proposed scheme accelerates the guarantee of the loss, delay, and jitter requirements because the response time for flow control can be extremely reduced up to a quarter of the Round Trip Time (RTT) on average while minimizing the signaling overhead. Simulation results show that our mechanism can guarantee a 10-3 loss-rate under any traffic load while offering satisfactory levels of delay and jitter for delay-sensitive applications.