Hybrid optical switching (HOS) combines the advantages of optical circuit switching (OCS) and optical burst switching
(OBS). But HOS can not dynamically change the optical switching paradigm according to the traffic fluctuation. it can
not efficiently support burst traffic. And the utilization of some lightpath in HOS networks is low. To solve the problems,
a self-adaptive hybrid optical switching (S-HOS) is proposed in the paper. In S-HOS networks, ingress edge nodes
monitor the traffic between a pair of an ingress node and an egress node, and based on the monitor results edge nodes
self-adaptively adjust optical switching paradigm. Based on minimum burst length maximum assembly period algorithm,
a new assembly algorithm of S-HOS is proposed to improve the lightpath utilization and efficiently support burst IP
traffic. And a data channel scheduling is proposed to assign data channel resources for the lightpaths and data bursts by
regarding lightpath as a huge data burst. And it can decrease the complexity of hybrid optical switching and improve the
network performance. Simulation results show that S-HOS outperforms OBS in term of IP packet dropping probability
and end-to-end delay.
The proportional differentiated model is very convenient for network operators to quantitatively adjust the quality
differentiation among service classes. And optical burst switching (OBS) is considered as the promising switching
paradigm of optical internet. So it is very important for OBS to support the proportional differentiated model. A
preemption scheme based on batch-scheduling is proposed to provide proportional differential QoS for OBS networks in
the paper. The expected burst dropping probability equation of every service class is deduced from the proportional
differentiated model. When a batch burst control packets and their corresponding bursts are completely scheduled by
LAUC with burst arrival order and some bursts are scheduled unsuccessfully, the preemption scheme is triggered to keep
proportional burst dropping probability among service classes according to the expected burst dropping probability
equations. The proposed scheme adopts the batch scheduling based on LAUC and burst arrival scheduling order to
decrease burst dropping probability. And it adopts the preemption scheme to keep proportional burst dropping
probability among service classes. Simulation results show that the proposed scheme can provide proportional
differential QoS and efficiently decrease the burst dropping probability.
The paper proposes a close-looped decision-directed pre-equalization scheme for OFDM systems, which can be divided into two stages: i) initialization stage; ii) calibrating and tracking stage. At the first stage, the transmitter set the pre-load information to all ones, and the receiver estimates the real channel information and returns it to the transmitter; after that the receiver would view an almost-flat fading channel and directly decode the constellations, and when no error found, it remap the data to constellation to create a local pilot to obtain a better estimation of apparent channel for the transmitter to repeatedly adjust its pre-load information. Simulation results show that the performance of iterative pre-equalization is better than that of conventional pre-equalization and post-equalization in the receiver and will be much better at high SNR.
Recently, IP over WDM has been envisioned as dominant network architecture to meet the ever-increasing bandwidth requirement in the IP networks and to eliminate the intermediate layers and able to make better use of advanced optical technologies. Among existing several optical switching paradigms for IP over WDM, optical burst switching (OBS) is the more promising one, which combines the advantages of optical circuit switching (OCS) and optical packet switching (OPS), and can also loose the implementation complexity even though the optical random-access buffer is unavailable, and optical logic processing is not mature up to now. Therefore, OBS will play a very important role in next generation IP networks. However as much more trends shown, OBS-based IP optical network requires an appropriate control plane able to control and manage resource/service between IP and WDM. Currently, Generalized Multi-Protocol Label Switching (GMPLS) has been regarded as one of excellent candidate control planes for most of network scenarios because it enhances some issues of MPLS (including routing and signaling, link management, and fault protection and restoration), and also supports various granularity switching (such as packet, TDM timeslot, wavelength, waveband, and fibre-switched). Moreover, some practical deployments have shown GMPLS able to achieve automatic path provisioning and online network management. Therefore naturally, the integration and cooperation between GMPLS and OBS attracts more attentions from many research institutes and organizations. Of course, the similar concepts are originally given in the labeled OBS (LOBS) framework proposed by Dr. Qiao. Most of importance, LOBS provides the basic ideas for the collaboration of MPLS and OBS. However, how to efficiently integrate GMPLS and OBS to make the best of their advantages requires much more detailed discussions. To our knowledge, there are very few literatures and material to expatiate on the related issues. Here, the paper will present our some research results and viewpoints related to the integration and extension of GMPLS into OBS. Firstly, the paper proposes a GMPLS-based OBS network model for the integration of IP and WDM. Secondly, it defines the packets format for control and data information. Third, it also gives the node's functional architecture and the collaborative control operations between GMPLS and OBS. Finally, it proposes a unified software system to integrate the functions of GMPLS and OBS. Besides, the paper also presents some GMPLS enhancements to support OBS, such as traffic engineering, fault recovery, and link management, etc.
Recently, some solutions (such as UCLP, GARA and GridJIT, etc.) have been proposed to manage optical network resources as other grid resources. However, most of them are focused on using grid technologies to encapsulate the management and control functions of optical control plane. And actually, they do not perform schedule optical network resources as grid resources. This paper proposes an economic-based scheme for lightpath resources scheduling and leveraging in grid-enabled optical networks. We also present the scheduling model and algorithm, and finally demonstrate their effectiveness by experiments on GridSim.