共查询到20条相似文献,搜索用时 718 毫秒
1.
Bart Puype Didier Colle Mario Pickavet Piet Demeester 《Photonic Network Communications》2009,18(2):150-159
Multilayer traffic engineering (MLTE) serves to provide cross-layer online network optimization techniques to cope with rapid
variations and short-term evolutions in traffic patterns. MLTE extends traffic engineering as it exists in IP/MPLS-based technology
toward the multilayer IP/MPLS-over-optical transport network. In addition to the IP/MPLS traffic routing, MLTE exposes much
larger adaptation flexibility by building on next-generation automatic switched optical transport networks. These offer fast
setup and teardown of end-to-end multi-hop optical connections (lightpaths), which are offered to the IP/MPLS layer as dynamically
provisioned capacity. This dynamic nature leads to an IP/MPLS logical topology that can be reconfigured on the fly, and IP/MPLS
link capacity that can be up- or downgraded as client traffic demand varies. These MLTE techniques are generally used to increase
perceived network performance in terms of throughput or QoS. As such, a MLTE-managed network offers a better than best-effort
service. Many types of traditional and novel services are shifting toward IP/MPLS technology. Consequentially, MLTE algorithms
and strategies should be conceived with the characteristics of such services in mind. We present a MLTE strategy that can
be implemented in a robust and distributed way. This strategy is then taken as the starting point in a study which evaluates
its suitability to such services. We show how the strategy can be adapted considering service performance metrics such as
end-to-end delay, traffic loss, and routing stability, and how such service optimizations impact general MLTE objectives such
as IP/MPLS logical topology mesh size reduction.
相似文献
Bart PuypeEmail: |
2.
This paper proposes the use of the saturated cut (SC) method to improve the network performance through efficient dynamic
traffic grooming in IP/MPLS over WDM networks using an overlay model. With the SC information from the IP/MPLS layer, the
optical layer can calculate a lightpath between two node sets rather than the earlier suggested approach of calculating such
paths just between two nodes for better performance. We have used two criteria, bandwidth and path length, to find SCs and
have proposed two algorithms which incorporate this in the path inflation control (PIC) policy proposed earlier. Two typical
networks, NSF and COST239, were used for examining the network performance. The simulation results show that though both methods
can significantly improve the overall network performance the SC method is more efficient for a sparse network like the NSF
network rather than for a dense network like the COST239 network. Since calculating lightpaths for all node pairs for a SC
is time consuming, we propose a considerably simpler heuristic approach that can provide almost the same level of performance
improvement as the SC method but with much lower complexity.
相似文献
Hui WangEmail: |
3.
The article addresses a simulation-based optimization approach for allocation of ADMs in WDM optical networks with stochastic
dynamic traffic. Since ADMs are expensive, it is desirable that if each node in WDM optical networks can use a minimum number
of ADMs to achieve a near-ideal performance. In this article, first, the utilization statistics of ADMs are gathered by simulation.
Then, ADMs are allocated based on the utilization statistics. In this respect, a simple sorting mechanism is used. The distinguished
feature of the proposed approach is that it shows the way to allocate ADMs at the nodes of WDM optical networks with stochastic
dynamic traffic. The experimental results ensure that the proposed approach can solve the problem of allocating ADMs in practical
WDM optical networks considering stochastic dynamic traffic.
相似文献
Mrinal Kanti NaskarEmail: |
4.
Satoshi Konishi Xiaoqiu Wang Takeshi Kitahara Hajime Nakamura Toshinori Suzuki 《Wireless Personal Communications》2008,44(1):57-73
Traffic demand for real-time services as well as non real-time services has recently been increasing, due to the rapid improvement
in transmission bit-rate within communication networks. In the future ubiquitous network society, in addition to traffic demand
for user-to-user real-time communications services, traffic of real-time applications is set to explode due to new communications
traffic for machine-to-machine communications. This paper proposes “ultra low-latency mobile networks,” where the target value
for unidirectional end-to-end latency per IP packet is 10 ms, in order to establish a new communications infrastructure capable
of providing next-generation real-time services. This paper introduces a model of such ultra low-latency mobile networks and
the results of a feasibility study are also presented. The simulation study shows the potential to realize a mobile network
with ultra low-latency of less than 10 ms for IP packets and a low IP packet error rate of < 0.1% through simulations. A
test-bed developed to measure actual latency is also introduced in this paper as well as measurement results using this test-bed.
The measurement results also confirm the possibility indicated by the simulation studies.
相似文献
Toshinori SuzukiEmail: |
5.
Dynamic restoration algorithms which support real-time and multi-services recovery are significant for the survivability of
WDM (wavelength division multiplexed) networks. In this article, an intelligent dynamic restoration algorithm for multi-services
in WDM networks based on the partheno genetic algorithm is proposed. In these networks, partial wavelength conversion is used.
The algorithm is implemented within an interconnected multilayer-graph model and two kinds of optical networks matrix models.
Compared with the basic restoration scheme, the proposed algorithm can make use of available network state information and
can restore the affected multi-services fast and parallel. Simulation showed that the proposed algorithm can improve the restoration
efficiency under high loads and reduce the service disruption ratio on the basis of fully utilizing resources of the network.
相似文献
Na ZhuEmail: |
6.
In optical wavelength-division multiplexing (WDM) networks, traffic can be unevenly distributed across the network causing
inefficient utilization of resources. To solve this problem, an improved soft preemptive (SP) scheme is proposed by considering
dynamic resource distribution to deal with the uneven network utilization. A novel unevenly distributed traffic model in cross-time-zone
networks is also presented to evaluate the efficiency of the new scheme. Compared with other schemes such as normal shortest
path first (SPF) routing and wavelength conversion (WC), the new proposed scheme results demonstrate significantly better
performance with respect to the network utilization and overall network blocking probability.
相似文献
Nan HuaEmail: |
7.
Der-Rong Din 《Photonic Network Communications》2009,18(1):1-13
In a Wavelength Division Multiplexing (WDM) network, the performance of the virtual topology (VT) designed for a pre-specified traffic pattern can be improved
by performing virtual topology reconfiguration (VTR). Simultaneously, the provision of survivability of WDM networks is important, because the transmission of huge data
should be protected when a fiber fails. Thus, the combination of survivability and reconfiguration is an important issue in
WDM networks. In this paper, the Virtual Topology Reconfiguration Problem (VTRP) in survivable WDM networks with a reconfiguration constraint is studied. Given the physical topology, dedicated path-protection VT, and a new traffic demand matrix, the goal of VTRP
is to reconfigure the current VT under the pre-specified reconfiguration constraint so that the objective value can be minimized.
The object cost of VTRP is the average weighted propagation delay (AWPD). Because designing a polynomial time algorithm to find the optimal solution of VTRP is impractical, in this paper,
a simulated annealing (SA) algorithm and a genetic algorithm (GA) are proposed to solve this problem. Experimental results of these algorithms are also given.
相似文献
Der-Rong DinEmail: Email: |
8.
A hierarchical network model can effectively reduce the complexity of routing and wavelength assignment (RWA) in wavelength
division multiplexing (WDM) networks compared to a flat model. However, the resource utilization may greatly suffer if the
hierarchical architecture is not properly arranged. By considering the degree of each WDM node and the location effect, this
paper proposes a systematic approach to construct the hierarchical topology in WDM networks so that resource utilization can
be maximized. Simulation results demonstrate that the performance of the proposed scheme is superior to that of another scheme.
相似文献
Yen-Wen Chen (Corresponding author)Email: |
9.
Distributed lightpath provisioning in wavelength-division multiplexing (WDM) networks has gained wide research interests.
In this article, we study the performance of distributed lightpath provisioning in WDM networks with dynamic routing and wavelength
assignment (RWA). Specifically, we consider the case where routing of each lightpath is calculated based on globally flooded
link-state information, and wavelength assignment is decided through local information exchanges. Simulation results show
that such schemes steadily outperform those schemes with only global flooding or only local information exchanges. More significantly,
the impacts of various factors on the proposed scheme, including RWA algorithm, network topology, number of wavelengths per
fiber, global flooding interval, and traffic load, have been evaluated. Such evaluations help to achieve some insights useful
for the future developments of efficient lightpath provisioning schemes.
相似文献
Gaoxi XiaoEmail: |
10.
I-Shyan Hwang Zen-Der Shyu Chun-Che Chang Jhong-Yue Lee 《Photonic Network Communications》2009,18(2):160-173
This study proposes a novel cost-based fault-tolerant WDM-EPON (CFT-WDM-EPON) to provide overall protection. It only equips
a backup feeder fiber to recover the system failure. Additionally, a prediction-based fair wavelength and bandwidth allocation
(PFWBA) scheme is proposed to enhance the differentiated services for WDM-EPON based on dynamic wavelength allocation (DWA)
and prediction-based fair excessive bandwidth reallocation (PFEBR) from our previous work. PFEBR involves an early-DBA mechanism,
which improves prediction accuracy by delaying report messages of unstable traffic optical network units (ONUs), and assigns
linear estimation credit to predict the arrival of traffic during waiting time. DWA can operate in coordination with an unstable
degree list to allocate the available time of wavelength precisely. Simulation results show that the proposed PFWBA scheme
outperforms WDM IPACT-ST and DWBA3 in terms of packet delay, jitter performance, throughput, wasted bandwidth, gain ratio
of bandwidth, and packet loss.
相似文献
Jhong-Yue LeeEmail: |
11.
In this article, a genetic evolutionary algorithm is proposed for efficient allocation of wavelength converters in WDM optical
networks. Since wavelength converters are expensive, it is desirable that each node in WDM optical networks uses a minimum
number of wavelength converters to achieve a near-ideal performance. The searching capability of genetic evolutionary algorithm
has been exploited for this purpose. The distinguished feature of the proposed approach lies in handling the conflicting circumstances
during allocation of wavelength converters considering various practical aspects (e.g., spatial problem, connectivity of a
node with other nodes) rather than arbitrarily to possibly improve the overall blocking performance of WDM optical networks.
The proposed algorithm is compared with a previous approach to establish its effectiveness and the results demonstrate the
ability of the proposed algorithm to efficiently solve the problem of Optimal Wavelength Converters Allocation (OWCA) in practical
WDM optical networks.
相似文献
Mrinal K. NaskarEmail: |
12.
Jae-Woo So 《Wireless Personal Communications》2008,47(2):247-263
While the voice over Internet protocol (VoIP) services is expected to be widely supported in wireless mobile networks, the
performance of VoIP services has not previously been evaluated in the IEEE 802.16e orthogonal frequency division multiple
access (OFDMA) system taking the adaptive modulation and coding scheme into consideration. To support real-time uplink service
flows, three different types of scheduling have been designed in the IEEE 802.16e standard: the unsolicited grant service
(UGS), the real-time polling service (rtPS), and the extended rtPS (ertPS). In this paper, we compare the three real-time
scheduling algorithms in terms of the performance of VoIP services by using the analytical and simulation models that we developed.
相似文献
Jae-Woo SoEmail: |
13.
Li-Der Chou Jui-Ming Chen Hung-Sheng Kao Shao-Feng Wu Wayne Lai 《Mobile Networks and Applications》2006,11(6):873-887
As the mobile networking technologies evolve, people are able to access the Internet through heterogeneous wireless access
networks, such as WLAN, GPRS, 3G and Beyond 3G networks. For the coverage, bandwidth and cost of these heterogeneous mobile
access networks are quite different, a mobile host may hand over among them, and this is called vertical handoffs. One of
the most important issues for heterogeneous mobile networks is that vertical handoffs may degrade the quality of the time-sensitive
streaming media services, even interrupt them. To overcome the problem, in the paper a multicast-based redundant streaming
architecture is proposed. The proposed architecture is implemented in the all-IPv6 heterogeneous mobile networks. Five experiments
are performed to evaluate the performance of the proposed architecture. The experimental results and the analysis show that
the proposed architecture is capable of providing seamless streaming services even if the vertical handoffs or the traffic
congestion occurs. Moreover, it is found that the traffic overhead is only 1.0368% per vertical handoff for each mobile access
network, and thus the feasibility of the proposed architecture is demonstrated.
相似文献
Jui-Ming ChenEmail: |
14.
P. P. Sahu 《Photonic Network Communications》2008,16(3):233-238
In this paper, two traffic grooming approaches based on alternate path routing are proposed to accommodate a greater number
of connections in optical networks. In the first approach (called as Source_SWG), the connections of same source and different
destinations along a path are groomed in a wavelength channel, whereas in the second approach (called as Des_SWG), the connections
of the same destination and different sources along a path are groomed in a wavelength channel. These approaches are compared
with existing heuristic traffic grooming algorithms based on fixed routing. It is found that both the approaches provide less
wavelengths than the existing heuristic traffic grooming algorithms for establishment of all the connections present in the
network. The comparative studies of these approaches are also made under restricted shared protection. It is seen that in
case of Source_SWG, the number of wavelengths required for establishment of all the connections present in the network is
less than that for Des_SWG.
相似文献
P. P. SahuEmail: |
15.
Yan Zhang Yifan Chen Jianhua He Cheng-Xiang Wang Athanasios V. Vasilakos 《Wireless Personal Communications》2009,50(1):99-114
Orthogonal frequency division multiplexing (OFDM) is becoming a fundamental technology in future generation wireless communications.
Call admission control is an effective mechanism to guarantee resilient, efficient, and quality-of-service (QoS) services
in wireless mobile networks. In this paper, we present several call admission control algorithms for OFDM-based wireless multiservice
networks. Call connection requests are differentiated into narrow-band calls and wide-band calls. For either class of calls,
the traffic process is characterized as batch arrival since each call may request multiple subcarriers to satisfy its QoS
requirement. The batch size is a random variable following a probability mass function (PMF) with realistically maximum value.
In addition, the service times for wide-band and narrow-band calls are different. Following this, we perform a tele-traffic
queueing analysis for OFDM-based wireless multiservice networks. The formulae for the significant performance metrics call
blocking probability and bandwidth utilization are developed. Numerical investigations are presented to demonstrate the interaction
between key parameters and performance metrics. The performance tradeoff among different call admission control algorithms
is discussed. Moreover, the analytical model has been validated by simulation. The methodology as well as the result provides
an efficient tool for planning next-generation OFDM-based broadband wireless access systems.
相似文献
Athanasios V. VasilakosEmail: |
16.
We consider the problem of maximizing the lifetime of a given multicast connection in wireless networks that use directional
antennas and have limited energy resources. We provide a globally optimal solution to this problem for a special case of using
omni-directional antennas. This graph theoretic approach provides us insights into more general case of using directional
antennas, and inspires us to produce a group of heuristic algorithms. Experimental results show that our algorithms outperform
other energy-aware multicast algorithms significantly in terms of multicast lifetime.
相似文献
Song GuoEmail: |
17.
Utpal Biswas Ujjwal Maulik Anirban Mukhopadhyay Mrinal Kanti Naskar 《Photonic Network Communications》2009,18(1):105-115
Traffic grooming in optical networks is the process of multiplexing and demultiplexing low-speed traffic streams onto high-speed
wavelengths. The research in the domain of traffic grooming mainly focuses on minimizing number of SONET add/drop multiplexers
(SADMs) in SONET/WDM rings and it has been shown that they can potentially be reduced by careful assignment of low-speed traffic
streams onto high-speed wavelengths. However, the cost of the network not only depends on the number of SADMs, but also the
number of wavelengths and the grooming ratio. It is often the case that all of them cannot be minimized simultaneously. In
this article, the problem of minimization of cost of a SONET/WDM unidirectional ring has been modeled as a multiobjective
optimization problem which simultaneously minimizes the number of SADMs, the number of wavelengths, and the grooming ratio.
A popular multiobjective genetic algorithm (NSGA-II) has been used as the underlying optimization tool. The resultant set
of near-Pareto-optimal solutions contains a number of nondominated solutions, which the user can judge relatively and pick
up the most promising one according to the problem requirements. Performance of the proposed algorithm has been demonstrated
on different network topologies.
相似文献
Mrinal Kanti NaskarEmail: |
18.
Haitham S. Hamza 《Photonic Network Communications》2009,17(3):277-291
In this paper, we propose a new Benes-type wavelength division multiplexing (WDM) optical network with space-wavelength switching
capability. Intuitively, adding wavelength switching capability to space Benes networks requires the use of additional hardware
components (i.e., wavelength converters). However, in this paper, we show that a Benes network with full-permutation capability
in both space and wavelength domains can be designed using a smaller number of hardware components but the same number of
stages as that in a space-only Benes network. In addition, wavelength conversion in the proposed network occurs only between
two pre-defined wavelengths, eliminating the need for any expensive wide-range wavelength converters. The proposed Benes network is based
on the newly proposed concept of wavelength-exchangeable permutation networks. Wavelength-exchangeable networks implement
single-step space and wavelength switching and hence reduces the number of hardware components. We show that, such wavelength-exchangeable
networks possess some interesting properties that can be used for designing routing algorithms to improve signal quality.
相似文献
Haitham S. HamzaEmail: |
19.
We explain a systematic way of interfacing data-flow hardware accelerators (IP) for their integration in a system on chip.
We abstract the communication behaviour of the data flow IP so as to provide basis for an interface generator. Then we measure
the throughput obtained for different architectures of the interface mechanism by a cycle accurate bit accurate simulation
of a SoC integrating a data-flow IP. We show in which configuration the optimal communication scheme can be reached.
相似文献
Tanguy Risset (Corresponding author)Email: |
20.
In this article, we find that the limiting hop count in a lightpath impacts on the performance of optical networks. Based
on this observation, we propose a dynamic hop count shifting (DYHOS) algorithm that limits the hop count of lightpaths dynamically,
depending on the traffic load. The proposed algorithm searches an available route, while minimizing the waste of network resources
and limiting excessive traffic on the network. Hence, the proposed algorithm increases the network throughput and reduces
the blocking probability. Comparing with shortest path routing and adaptive path routing algorithms, we show the performance
of the proposed algorithm has the lowest blocking probability influenced by the hop count of lightpaths for a given routing
algorithm.
相似文献
Jeonghoon MoEmail: |