As the applications of circular polarization (CP) antennas are widely used in the wireless communications, it is
significant to improve the CP antenna performance in aspect of axial ratio at the boresite direction. A good CP
performance is always desired. In this paper, we fabricate the amendatory one-dimensional photonic crystals for SHF
reflector antenna based on previous simulation results to compensate the circular-polarization discrimination as
encountered in many antenna's applications. The goal is to widen the beamwidth of radiation for crossed-dipole. The
performance is evaluated by measuring the 3dB axial ratio. Transfer matrix theory of multi-layer theory is used to solve
the field distribution cross layer. Although some tabulate plane-based (TPB) compensations can achieve a great
improvement for the crossed-dipole based reflector antenna, but it can only compensate the CP in a specified direction
and may distort in other directions. The one-dimensional approach can smooth the discrimination introduced by the
reflector and noise. The energy distribution of TE/TM polarizations are regulated with a one dimensional photonic
crystal to achieve a broader beamwidth, also the reflector antenna is fabricated and measured to validate the efficiency of
the proposed approach. The measured results show that the beamwidth is much wider than that before compensation.
The gain of 3D plot and the radiation patterns are also shown to verify if the side effect of compensation.
In this paper, a p-cycle generation algorithm is proposed that can protect service of static traffic model in WDM network.
As the basic p-cycle sets calculated by algorithm such as the straddle link algorithm (SLA) always contain a straddle link
in it. That is why the protection efficiency is higher than bidirectional line switch ring (BLSR). Any idle resource can be
used for traffic restoration. But if the resource is not configured carefully then not all the resource of idle state can be
utilized efficiently. Some extensions of algorithms are brought into effect to improve the protection capability. Based on
these extensions, a novel iterative expanding p-cycle is introduced. A platform is constructed in OPNET modeler to
verify the performance of this algorithm. Simulation results show that after several expansions for the basic p-cycle sets,
the efficiency is improved. The pre-configured resource is deployed before any requests come. Comparison between
different network topologies is studied. Finally, the results are analyzed and some directivity is given for further
research.
As the scalability of network grows rapidly, multiple carriers can interoperate under a common control plane and operate
separately. A large network is often composed of a lot of network nodes which incurs great burdens for network
management and controlling bandwidth spending. Networks comprised of LSRs with different data plane switching
layers controlled by a single GMPLS control plane instance is referred as multi-region network (MRN). Most of previous
researches are focus on network partition with the principles of shortest path first or simply based on the geographical
position. However, the performance of the call block ratio is always not so good. In this paper, we consider a kind of
least imbalance flows among all the sub domains, which aims at providing relative average load for each routing area in
the network. This work also introduces a method for the address confliction while more than two areas are united, and
also the address.
A cost-effective capacity planning method of WDM networks is proposed for increase of traffic load. An improved costbased
ant colony algorithm is presented from pheromone increase and update mechanisms to solve the planning problem.
Simulation results show the applicability of our planning method.
Clock synchronization is an essential problem faced by packet transport network. PTP (precise time protocol) can be
used to solve this problem.Its feasibility has been verified by related literatures. In this paper, we use the OPNET
simulation platform to further study the key factors affect the clocks' accuracy of packet-based synchronization schemes,
e.g., queuing disciplines, network traffic load, whether low-pass filter is used or not, and deployment of the PTP enabled
router. We intend to answer the question how much influence can each factor make to the clocks' synchronization
performance.
With ever increasing requirements posed by significant advances in networking, service providers may use traffic
engineering (TE) techniques to efficiently manage resources and provide consistent quality of service (QoS). Briefly,
constraint-based path computation involves the pruning of links that do not satisfy constraints and subsequently using the
shortest path algorithm on the resulting sub-graph. This process is simple and efficient when the path involves only one
domain, but can potentially become severely resource heavy, complex, and inefficient when multiple domains are
involved. To address this problem, the Path Computation Element (PCE) architecture has been proposed to allow multilayer
path computation to be simple and efficient. The PCE architecture introduces a special computational entity that
will cooperate with similar entities to compute the best possible path through multiple layers. This paper analyses the
PCE architecture and the traditional method to computing the routing through multiple layers, and then an improved
scheme of path selection for multi-layer network based on PCE and VNTM is present and evaluated on the simulation
platform of NSFNET, which is used to avoid traffic redundancy caused by low layer's invisibility to the high layer.
A reconfigurable protection is extended in ASON survivability testbed SURBED, the performance and extra overhead
are presented and also compared with several survivability techniques (1+1, shared mesh, rerouting, etc) in SURBED.
Pre configured protection cycles (p-cycle) is a kind of preconfigured protection mechanism that can have mesh-like
resource efficiency and ring-link protection speed. But under multi-region survivable network, the topology and resource
information is not always available due to policy reasons or other else, so distributed approach with agent negotiation is
attractable. As the dimensions of WDM optical network grows larger and larger, it tends to be a mesh structure. Based
on SURBED, we take extensive simulation to investigate the performance of different signaling strategies by multiregion
agent negotiations. Unlike previous work, we focus on the reconfiguring process rather than the switching over
operation of control plane in ASON. The backbone is overlaid, in which most of devices are IP router networks. Routers
are interconnected by fibers or SDH or WDM links. It is the same with non-reconfigured p-cycle, the reconfiguration
need a criterion, and here we use the network real-time performance as a reconfiguration trigger to take actions on pcycle
reconfiguration.
T-MPLS is a connection-oriented packet switched solution for transport networks. In this paper, we investigate the signaling mechanism in T-MPLS control plane with BRR-N and SRR strategies and simulate it in OPNET modeler.
The standardization process is pushed by ITU-T and IETF. T-MPLS is much easier to achieve a convergent packet platform for any L2 protocol. It focuses on the packet transport application that adheres to the standard groups. With the proposed mechanisms, the performance was deeply studied in this paper for the controlling overhead and the block probability of the transport network. The realization of the T-MPLS network router model and its associated structure is also presented to show the detail functional components. The convergent packet transporting platform for any L2 and L3 protocols is attractive for future telecom applications.
Keywords: T-MPLS, backward reservation, forward reservation, packet transport
In this paper, we propose and describe a new distributed reservation protocol for establishing lightpaths in multi-domain optical networks. Distributed reservation scheme is a promising solution for resource reservation and path computation element (PCE), proposed by IETF and considered as a promising scheme to deal with the issue of path computation in support of multi-domain networks, establishes architecture to solve the reservation problem in multi-domain network. Thus, we propose a novel distributed reservation mechanism (PBDR) for PCE-based multi-domain optical network to ease the inefficiency of the step by step reservation process (Source Initiated Reservation and Destination Initiated Reservation). Also, we evaluate the performance of the proposed PBDR through simulation and the result shows the efficiency and availability of the distributed reservation scheme proposed in multi-domain optical network.
T-MPLS is regarded as one of the most important transport technologies in the next generation network, it a
connection oriented packet transport technology develop from MPLS techniques, now defined by ITU-T SG13 &
SG15. In this paper, we analyze the architecture of the transport MPLS networks, the most important building
blocks for the modular design of the common T-MPLS equipment are introduced. And based on the functional
blocks, a four-layer simulation T-MPLS node structure is developed. And the simulation environment is introduced.
Many kinds of research can be done using this T-MPLS simulation tool, such as the research of the feasibility
T-MPLS design, the inter-working between the T-MPLS and the PWE.
KEYWORDS: Network architectures, Networks, Switching, Signal processing, Seaborgium, Asynchronous transfer mode, Switches, Time division multiplexing, Cerium, Control systems
T-MPLS is a connection-oriented packet switched solution for transport networks. The standardization process is
pushed by ITU-T and IETF, many recommendation appeared in these days. T-MPLS is much easier to achieve
a convergent packet platform for any L2 protocol. It focuses on the packet transport application that adhere to the
standard groups. Although IETF PWE3 WG have already specified the common architecture for L2/L3 service
encapsulation, as different service always has different characteristics. So we propose a control mechanism for
dual label transport across T-MPLS in this paper, through which we can easily achieve a convergent packet
transporting platform for any L2 and L3 protocols, . At last, a flow chart for T-MPLS realization and a FSM
structure have been introduced.
p-cycle provides a new protection scheme which provides fast protection switching time as that in ring networks and high resource efficiency as that in mesh networks. Extensive research has shown that the concept of p-cycle can also be applied to Automatically Switched Optical Network (ASON), which is the direction of the next generation optical network. This paper proposes a novel dynamic p-cycle algorithm in ASON named Routing in Spare plus Protecting Capacity Dynamic p-cycle Algorithm (RSPC-DP). Different from traditional dynamic p-cycle algorithms, the proposed algorithm takes traffic forecast matrix into account, and it is capable of tracing the changes of network environment and dynamic traffic matrix on-line. Extensive simulation results show that the proposed algorithm outperforms the existing algorithms significantly.
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