共查询到20条相似文献,搜索用时 31 毫秒
1.
Energy conservation and interference reduction are the two ultimate goals of topology control in wireless multihop networks.
However, the existing energy-conserving algorithms rarely consider interference reduction or at most consider it implicitly.
It has been proved that the power-efficient topology does not guarantee low interference. Considering that in any topology,
the nodes affected by the communications between any other nodes should be as few as possible, we propose in this article
two algorithms, the interference-aware local minimum spanning tree (MST) based algorithm (IALMST) and the interference-bounded
energy-conserving algorithm (IBEC). In IALMST, each node builds its local MST independently according to the costs of interference
and energy consumption, while in IBEC, each node commonly selects the edge with the least energy consumption, and only when
the interference exceeds a predefined bound, it is allowed to select a more expensive edge to reduce interference. Theoretical
analysis and simulations illustrate that both algorithms can effectively conserve energy and reduce interference.
相似文献
Yao ShenEmail: |
2.
By taking advantage of statistical multiplexing gain in the burst level, optical burst switching (OBS) technology enables
optical Internet to handle huge volume of data in an efficient manner without requiring optical buffers in the optical domain.
However, when congestion builds up in the optical network core, large amount of data might be lost. In this article, we propose
an efficient optical burst control algorithm that operates based on the awareness of future burst traffic condition to eliminate
the effect of congestion reaction delay. The proposed algorithm takes advantage of multiple statistics to improve the estimation
accuracy.Through performance evaluation, it is verified that the proposed algorithm proactively controls inbound burst traffic
so that the OBS network can stay in a stable traffic condition while keeping the network throughput high.
相似文献
Myungsik YooEmail: |
3.
EasiTPQ: QoS-Based Topology Control in Wireless Sensor Network 总被引:1,自引:0,他引:1
With the rapid development of wireless sensor networks (WSNs), the requirements for quality of service (QoS) are growing,
particularly in applications where real time imaging, video or audio communications are involved. The system needs to meet
both optimized energy consumption design metric and to satisfy certain QoS requirements simultaneously from long view. Different
from most of the existing works which deal with resource allocation (e.g., scheduling or buffering) or routing strategy to
achieve QoS, we extend QoS support to the topology control layer by introducing a number of active nodes distributed in a
gradient fashion based on their logical distances to the sink node. In this paper, a novel topology control algorithm, namely
EasiTPQ (Easy QoS-based topology control) is proposed to improve QoS performance in wireless sensor networks. Simulation results
show that data loss rate and latency are averagely improved by 55 and 45%, respectively.
相似文献
Wei Liu (Corresponding author)Email: |
4.
Routing on pre-configured topology for dynamic optical networks 总被引:1,自引:0,他引:1
Yongli Zhao Jie Zhang Dahai Han Lei Wang Wanyi Gu Yuefeng Ji 《Photonic Network Communications》2009,17(3):299-310
5.
In this article we describe a feedback-based OBS network architecture in which core nodes send messages to source nodes requesting
them to reduce their transmission rate on congested links. Within this framework, we introduce a new congestion control mechanism
called congestion control with explicit reduction request (CCERQ). Through feedback signals, CCERQ proactively attempts to
prevent the network from entering the congestion state. Basic building blocks and performance tradeoffs of CCERQ are the main
focus of this article.
相似文献
Farid FarahmandEmail: |
6.
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: |
7.
Adaptive Max SNR Packet Scheduling for OFDM Wireless Systems 总被引:1,自引:1,他引:0
Noureddine Hamdi 《Wireless Personal Communications》2008,46(2):223-232
In this paper, we consider scheduling and resource allocation for a downlink in a wireless OFDM system. If each broadcast
sub channel is allocated to a user according to max SNR selection, optimal system throughput is obtained for the cost of a
significant loss in fairness among users. As a solution to resolve this issue and in an attempt at reaching a compromise between
fairness and throughput, we propose to add to the max SNR scheme a weak control based on user QoS requirements. In this work,
user latency between two successive channel accesses is considered as a parameter for the control. The feedback of quantized
channel state information (CSI) is proposed to reduce the feedback burden. Performance analysis of the proposed scheme has
been presented to illustrate the capacity-fairness-feedback trade-off of the considered scheme compared to max SNR and proportional
fair algorithms used as benchmark.
相似文献
Noureddine HamdiEmail: |
8.
High speed data transmission in wireless networks demands better radio resource management schemes. A fair packet scheduling
is proposed for downlinks of a cellular TD-CDMA system for delay-tolerant applications. It is based on the combined consideration
of channel conditions, required throughput and achieved average throughput. A system dependent parameter is introduced to
control the maximum achievable date rate as well as the degree of fairness. Through analysis and simulation, we study the
tradeoff between system throughout (i.e., efficiency) and individual throughput (i.e., fairness). The relative performance
between the proposed scheme and the traditional schemes is evaluated through simulation to confirm the analytical observations.
The sensitivity of the system tolerance factor towards efficiency and fairness is also investigated.
相似文献
Alagan AnpalaganEmail: |
9.
In this article, new Dynamic Bandwidth Allocation (DBA) algorithms which give high priority to some ONUs corresponding to
important agencies are studied in order to manage emergency cases causing severe network traffic. In order to deal with such
cases, the network state is divided into two states, namely the normal and the emergency states. We apply the Weighted Round Robin (WRR)-based algorithm to the normal state, and three priority-based DBA algorithms
are applied to the emergency state. These algorithms are different from each other according to the mode of protecting non-priority
ONUs from starving. Each algorithm is analyzed in terms of utilization of the uplink bandwidth and the average packet delay.
Simulation and theoretical results show that the proposed algorithms are working properly at the emergency state and can satisfy
more stringent QoS requirements than WRR algorithms.
相似文献
Kyoung-Rok ChoEmail: |
10.
Yining Cao Hongyi Xie Xiaoping Zheng Yanhe Li Hanyi Zhang 《Photonic Network Communications》2009,18(2):211-217
In this article, we consider the capacity fairness problem in IP-over-WDM networks. Since connections with different bandwidth
granularities may be established over a shared lightpath, fairness in bandwidth allocation among different users becomes a
crucial problem. A simple, yet efficient hop constraint-based admission control scheme is proposed to accommodate more high-bandwidth
requests. Through rejecting some of the low-capacity requests that would go through alternative paths with more hops and thus
would consume a larger amount of bandwidth, the blocking probability of high-capacity requests reduces notably. Numerical
results show that this proposal achieves significant improvement in capacity fairness without raising the overall blocking
probability. In addition, it achieves excellent fairness performance at both light and heavy loads by selecting the rejection
probability dynamically.
相似文献
Yining CaoEmail: Email: |
11.
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: |
12.
Zizhi Qiao Ramesh K. Venkatasubramanian Lingfen Sun Emmanuel C. Ifeachor 《Wireless Personal Communications》2008,45(2):189-207
Jitter buffer plays an important role in Voice over IP (VoIP) applications because it provides a key mechanism for achieving
good speech quality to meet technical and commercial requirements. The main objective of this paper is to propose a new, simple-to-use
jitter buffer algorithm as a front-end to conventional static or adaptive jitter buffer algorithms to provide improved performance,
in terms of enhanced user-perceived speech quality and reduced end-to-end delay. Supported by signal processing features,
the new algorithm, the so-called Play Late Algorithm, alters the playout delay inside a speech talkspurt without introducing
unnecessary extra end-to-end delay. The results show that the new algorithm achieves the best performance under different
network conditions when compared to conventional static and adaptive jitter buffer algorithms. The results reported here are
based on live tests and emulated network conditions on real mobile phone prototypes. The mobile phone prototypes use AMR codec
and support full IP/UDP/RTP stack with IPSec function in some of the tests. The method for perceived speech quality measurement
is based on the ITU-T standard for speech quality evaluation (PESQ).
相似文献
Zizhi QiaoEmail: |
13.
Providing differentiated services in IP/MPLS over WDM networks has attracted a lot of recent attention. This article extends
the Path Inflation Control (PIC) policy recently proposed by us to provide differentiated services in IP/MPLS over WDM networks
with traffic grooming. Three different algorithms are considered for provisioning differentiated services. The simulation
results show that, with two of the three algorithms, the network cannot only provide differentiated services when the traffic
load is high but also gives significantly lower blocking for the lower priority class traffic and for the overall traffic
at low traffic loads.
相似文献
Sanjay K. BoseEmail: |
14.
We present an adaptive antenna algorithm for Gaussian minimum-shift keying (GMSK)-based cellular systems with beamformer weights
that are iteratively computed using re-encoded data to suppress cochannel interference (CCI). Filtered training sequences
are proposed in order to compensate for the effects of timing offsets that occur for asynchronous cochannel signals. Also,
we extend the receiver to include a linear equalizer that mitigates intersymbol interference (ISI). Various multistage receivers
incorporating the proposed beamformer and equalizer algorithms are presented. Their performance is evaluated using simulated
and real time-division multiple-access (TDMA) data, demonstrating that the proposed beamforming algorithms suppress CCI and
significantly improve the performance compared to a conventional GMSK receiver.
相似文献
Richard P. GoochEmail: |
15.
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: |
16.
Maciej Jan Zawodniok Sarangapani Jagannathan 《International Journal of Wireless Information Networks》2007,14(4):251-263
In this paper, two novel energy-efficient rate adaptation schemes are presented. The proposed protocols use the Distributed
Power Control (DPC) algorithm to predict the channel state and determine the necessary transmission power which optimizes
the energy consumption. The first proposed rate adaptation scheme heuristically alters the modulation rate to balance the
energy-efficiency and the required throughput which is estimated with queue fill ratio. Moreover, the back-off scheme is incorporated
to mitigate congestion and reduce packet losses due to buffer overflows thus minimizing energy consumption. Consequently,
the nodes will conserve energy when the traffic is low, offer higher throughput when needed and save energy during congestion
by limiting transmission rates. The second rate adaptation scheme employs dynamic programming (DP) principle to analytically
select modulation rate and a burst size to be used during transmission. The proposed quadratic cost-function minimizes the
energy consumption while alleviating network congestions and buffer overflows. The proposed DP solution renders a Riccati
equation ultimately providing an optimal rate selection. The simulation results indicate that an increase in throughput by
96% and energy-efficiency by 131% is observed when compared to other available protocols, for example Receiver Based AutoRate
(RBAR).
相似文献
Sarangapani JagannathanEmail: |
17.
An analytical model is derived to evaluate the performance of an optical switch using a feed-forward fiber delay line (FDL)
per output for contention resolution. Two different forwarding algorithms for the switch are presented and evaluated: a simple
forwarding algorithm (SFA) that is easier to implement, and an enhanced algorithm that provides better performance in terms
of both packet loss probability and packet delay. The analytical model can be utilized with both packet and burst switching
schemes to characterize the performance of the proposed architecture. Results show that the proposed architecture reduces
the packet loss probability compared to that without FDLs. Finally, the same architecture is shown to be capable of supporting
Quality of Service (QOS).
相似文献
Anura Jayasumana (Corresponding author)Email: |
18.
The paper sets forth an improved edge-directed image interpolation algorithm with low time complexity which is the combination
of Newton’s method and edge-directed method. It first partitions images into homogeneous areas and edge areas by setting a
preset threshold value based on the local structure characteristics, and then specified algorithms are assigned to interpolate
each classified areas, respectively. In this way, it achieves the goals of real-time interpolation and good subjective quality.
The interpolated images have higher peak signal noise ratios (PSNR) and better visual effects using proposed method than that
of using other algorithms referred to in this paper. Experimental results show that proposed method is highly performed in
image interpolation.
相似文献
Chen Zhi-FengEmail: |
19.
Víctor P. Gil Jiménez Thomas Eriksson Ana García Armada M. Julia Fernández-Getino García Tony Ottosson Arne Svensson 《Wireless Personal Communications》2008,47(1):101-112
In this paper, several algorithms for compressing the feedback of channel quality information are presented and analyzed.
These algorithms are developed for a proposed adaptive modulation scheme for future multi-carrier 4G mobile systems. These
strategies compress the feedback data and, used together with opportunistic scheduling, drastically reduce the feedback data
rate. Thus the adaptive modulation schemes become more suitable and efficient to be implemented in future mobile systems,
increasing data throughput and overall system performance.
相似文献
Arne SvenssonEmail: |
20.
Onur Alparslan Shin’ichi Arakawa Masayuki Murata 《Photonic Network Communications》2009,18(2):237-243
According to a famous rule-of-thumb, buffer size of each output link of a router should be set to bandwidth-delay product
of the network, in order to achieve high utilization with TCP flows. However, ultra high speed of optical networks makes it
very hard to satisfy this rule-of-thumb, especially with limited choices of buffering in the optical domain, because optical
RAM is under research and it is not expected to have a large capacity, soon. In this article, we evaluate the performance
of our explicit congestion control protocol-based architecture designed for very small Optical RAM-buffered optical packet
switched wavelength division multiplexing networks with pacing at edge nodes in order to decrease the required buffer size
at core nodes. By using a mesh topology and applying TCP traffic, we evaluate the optical buffer size requirements of this
architecture and compare with a common proposal in the literature.
相似文献
Onur AlparslanEmail: |