Burst segmentation (BS) is a high-efficiency contention resolution scheme in bufferless optical burst switching (OBS) networks. A prioritized BS scheme for quality of service (QoS) support is developed. Unlike the existing work on the BS scheme, the proposed BS model considers path-correlated factors, such as path length, the adjoining paths carrying traffic on a given path, and the multipriority traffic coming from all paths. Byte loss probability for high-priority and low-priority bursts under the time-based assembly approach and the length-based assembly approach to estimate the performance of the proposed BS scheme by comparing the cumulative distribution function of a burst length in an OBS ingress node (source) with that in an egress node (destination) is introduced. A preemptive BS policy for different priority bursts is proposed to support the QoS of the OBS network. Finally, a simulation is given to validate the proposed analytical model in an existing OBS network with two priority bursts. It is shown that the proposed BS scheme can realize the service differentiation for multipriority traffic under the consideration of network topology-dependent parameters.
In an optical burst switching core node, each output port is equipped with a different network interface unit that can provide a specific data rate. Bursts will use different probabilities of select output ports, which is in accordance to the path-length metric-based routing optimal algorithm and wavelength resource situation. Previous studies ignore this issue. We establish a burst-outputted model considering the different service rate of output ports and different port-selected probabilities. We calculate burst-blocking probability and analyze the relationship between service rate and output-port-selected probability in detail.
In optical burst switching (OBS) networks, burst contentions in OBS core nodes may cause data loss. To reduce this data loss, a retransmission scheme has been applied. However, uncontrolled retransmission may significantly increase network load and data loss probability, thus defeating the retransmission purpose. In addition, in a priority traffic existing OBS network, OBS nodes may apply different retransmission mechanisms to priority bursts for quality-of-service (QoS) support. We present a controlled retransmission scheme for prioritized burst segmentation to support QoS in OBS networks. Different from previous work in the literature, we set a different value to retransmission probability at each contention and propose a retransmission analytical model for a burst segmentation contention resolution scheme. In addition, we apply the proposed retransmission scheme to the prioritized burst segmentation for QoS support. We take into account the load at each link due to both the fresh and the retransmitted traffic and calculate the path-blocking probability and the byte loss probability for high-priority and low-priority bursts to evaluate the network performance. An extensive simulation is proposed to validate our analytical model.
In this paper, the delay issue in unequal outputting probabilities applied optical burst
switching (OBS) network has been proposed and analyzed. The average waiting
length of queue in optical buffer and the average total length of queue in OBS core
router have been given. Analytical results indicate that, the performance of delay will
affected by the ratio among different length traffic.
The simulating technique is used to investigate generating and distributing Ultra-Wide-Band signals depend on fiber
transmission. Numerical result for the system about the frequency response shows that the characteristics of band-pass
filter is presented, and the shorter the wavelength is, the bandwidth of lower frequency is wider. Transmission
performance simulation for 12.5Gb/s psudo-random sequence also shows that Gaussian pulse signal after transported in
fiber is similar to UWB wave pattern mask of FCC in time domain and frequency spectrum specification of FCC in
frequency domain .
In this paper, we present an analytical model to study the performance of unequal probability outputting issue in optical burst switching network. In our model, we give a method to evaluate the blocking probability for multi-class traffic at core router when they choose output ports depending on unequal probability.
We present an analytical model to study the multiclass-traffic-based optical burst switching system. In contrast with the previous on-off burst arrival process model, which is based on a single class of traffic and depends on just one probability of bursts to choose output ports, in our scheme we evaluate the blocking probability for multiclass bursts at the core router, which chooses output ports depending on differential probability, and we give some useful discussion for the design of real optical burst switching networks.
Segment-dividing model is appropriate for research on PMD. Mathematical deduction is made to change it into iterative model. It is easy to find the new model gives clear meaning in physics and reveals the process of PMD accumulation in fiber. It is applicable for being transplanted to analysis on PMD. This iterative method is put forward for practical numeration. When stochastic factor is taken into account on PMD analysis, more elements should be added. Thus statistical mode is put forward. In the statistical mode, the stochastic factor contains two parameters: the mean length of the whole little segments L and the number of the segments N. the choice on the mean length and the number of the segments is a complex problem. Research is done on this problem and results indicate that the choice of L determines the veracity of the statistical model.
Optical burst switching (OBS) network has been proposed as a novel network scheme which can realize IP over WDM and also been regarded as the trend of the next optical generation network. In OBS network, burst contention phenomena may often occur at the output data channel in core routers and the contention can bring on the data losing.
Optical composite burst switching (OCBS) has been regarded as an efficient approach for the resolution scheme in burst contention, which segments and drops the header of contending burst, but OCBS may bring unfairness to burst dropping, this unfairness causes the OBS network can't well support quality of service (QoS). The previous works that focus on the resolution approaches for the unfairness have some limitations and also could bring unfairness to OBS network. An improved resolution approach has been proposed to solve the unfairness of burst segmentation and dropping in optical burst switching multi-hop network in this paper, this approach not only could maintain the advantage of conventional resolution approach, which could make the packets loss probability coherence in
multi-hop network but also could decreases the data losing and increase the throughput for OBS network. At last, some simulations prove the validity of the proposed approach and it has the theoretic meaning to design the real OBS network in practice.
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