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1.
A dynamic routing scheme for public switched telephone networks is introduced which employs satellite broadcast to distribute
network load data. The proposed network architecture closely resembles the IN (Intelligent Network) architecture, whereby
the IN SCPs (Service Control Points) serve as so‐called Routing Control Points (RCPs). The key functions of an RCP are (i)
to execute the routing algorithm and issue routing instructions in response to routing queries it receives from its associated
switches for calls which overflow from the default network links, and (ii) to monitor and evaluate the pattern of received
routing queries to obtain an estimate for the traffic loads present in each RCP's domain of associated switches. Satellite
broadcast is used to distribute the load information among all RCPs in the network in a periodic fashion. This paper also
reports on the results of extensive call‐by‐call simulations. The objective of the simulations was to validate this new routing
scheme and compare its performance with well‐known existing schemes. Real traffic and network data as measured in the Austrian
PSTN were used in the simulations. The main results are that, under all realistic network and traffic conditions including
link and node failures, the proposed scheme yields lower blocking rates and significantly less routing and crankback attempts
than the existing dynamic routing schemes. Note that this is achieved in the absence of any load measurements within the switches.
As regards the periodic satellite based RCP‐RCP broadcast for the PSTN studied, it was shown that an update period of 10 seconds
yields an excellent routing performance which is close to the limit of a vanishing update period.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
2.
Tabu search for dynamic routing communications network design 总被引:1,自引:0,他引:1
This paper presents a tabu search approach for optimizing the link capacities in a dynamic routing telecommunications network.
The traffic between any two nodes in the network is routed over a one‐link direct path or, if no direct capacity is available,
over a two‐link alternate path. The alternate routing paths can be changed dynamically from hour to hour as the traffic between
pairs of nodes may vary with the time of day. The problem is to determine the optimal capacity level for each link in the
network to minimize cost while satisfying the grade‐of‐service constraints. Although the problem can be formulated as a nonlinear
integer programming problem, no efficient solution procedures are available. In this paper, we develop a two‐level tabu search
heuristic for solving the problem that utilizes probabilistic move selection and coordinated solution recovery strategies.
The macro level of the algorithm iteratively determines an hour for possible improvement and then the micro level seeks to
optimize the routing paths for that hour. Our computational experience with both real and simulated problems indicates that
significant savings can be obtained by this approach over the conventional network designs.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
3.
We consider a Virtual Path (VP) based ATM network supporting multiple traffic classes with heterogeneous traffic characteristics.
Using simple FIFO scheduling policy at the ATM multiplexer, we assume that all traffic require identical end‐to‐end quality
of service (QoS) requirement. The concept of effective bandwidth is used to determine the required bandwidth to guarantee
the specified QoS requirement. We study the problem of using dynamic routing to VP‐based ATM networks by transforming it into
an equivalent multi‐rate circuit‐switched network problem. To further simplify the analysis, we restrict the choice of path
to single‐link and two‐link routes. We propose a dynamic routing algorithm based on the Least Loaded Routing (LLR) with packing.
Simulation results are used to compare the performance of this algorithm with other dynamic routing schemes.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
4.
A novel network architecture based on the IEEE 802.6 metropolitan area networks (MAN) is proposed to integrate the wireless
and wired segments of a regional enterprise network (REN) within a city. This architecture functions like a distributed switch
for all types of services, reducing traffic congestion by sharing the high capacity link dynamically and facilitating signaling,
mobility management, call processing and network management through its distributed functions, transport facilities and broadcasting
capability. It also serves as a peripheral gathering network of REN traffic for transport over a wide area ATM/BISDN, enabling
integration of an enterprise's regional networks into a global EN. Two major wireless applications, i.e., wireless PABX (WPABX)
and wireless LAN (WLAN) are discussed to illustrate the advantages of this MAN‐based architecture. Although a REN is likely
to support a wide range of different services, voice and data will continue to be the predominant traffic generated by WPABXs
and WLANs, respectively, and are also representative of isochronous and asynchronous multimedia traffic carried by future
wireless networks. We compare the traffic capacity of several voice transport alternatives under integrated (voice/data) network
traffic with various data traffic loads, and study voice and data integration under three different integration schemes by
simulations. Results indicate that the MAN‐based architecture is most effective employing queue arbitrated (QA) access for
asynchronous traffic, pre‐arbitrated access for constant bit‐rate isochronous traffic, and the new reservation arbitrated
(RA) access for variable bit‐rate isochronous traffic, under a scheme that permits full sharing between QA and RA traffic.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
5.
LMDS/LMCS is a broadband wireless local loop, millimeter‐wave alternative to emerging integrated multiservice access networks.
Significantly large amounts of bandwidth – in the order of one GHz of spectrum – are made available to residential subscribers
or supported business users respectively that employ highly directional antennas and signal polarization to establish communication
with a central hub. Besides the requirement for dynamic bandwidth allocation capabilities, these networks should be able to
guarantee negotiated quality of service (QoS) levels to a number of constant‐length (ATM) – and possibly variable length (TCP/IP)
– packet streams. In this context, we analyze the performance of contention, polling/probing and piggybacking mechanisms that
will be used by the LMDS MAC protocol for the dynamic support of both real‐time and non‐real‐time traffic streams. More specifically,
we focus on the end‐to‐end performance of a real‐time variable bit rate connection for which the LMDS link is only the access
component of a multi‐link path through an ATM network. Results are presented on maximum end‐to‐end cell delays under a Weighted
Round Robin service discipline and buffer requirements are calculated for no‐loss conditions. In parallel, we also consider
the case in which variable length IP packet traffic is supported as such by the same wireless access network. Backbone interconnection
alternatives of LMDS hubs, multiple access proposals and scheduling algorithms are addressed in this framework.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
6.
Future cellular communication systems must seamlessly support services for a wide range of user needs, including voice, data,
video and multi‐media. It is envisioned that mobile users may do much computer processing in an off‐line mode but must occasionally
connect to a network in order to exchange data and/or files. For this purpose a communication session is initiated. During
the session the user has access to network resources, although this access may be shared with others. Owing to the mobile
environment, the user's connection to the network during a session may be severed. Since the mobile user can act semi‐autonomously,
such disconnections can be transparent. That is, the mobile user can continue to function in an off‐line mode while the system
will begin transparent automatic reconnection attempts to reestablish a link to the network. Only after a fixed (given) number
of such attempts to reconnect have failed, is the session deemed to have failed. The issue is complicated by the hostile mobile
radio environment and by user mobility. We consider session‐oriented communications and develop a tractable analytical model
for traffic performance based on multi‐dimensional birth–death processes. The approach allows consideration of various platform
types, such as pedestrians, automobiles, and buses, which may have very different mobility characteristics. Performance characteristics,
such as: blocking, forced session termination, carried traffic, the average time per suspension, and the average number of
suspensions per session, are calculated.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
In order to support diverse communication‐intensive real‐time and non‐real‐time data flows over a scarce, varying and shared
wireless channel with location‐dependent and bursty errors, we define a service model that has the following characteristics:
short‐term fairness among flows which perceive a clean channel, long‐term fairness for flows with bounded channel error, worst‐case
delay bounds for packets, short‐term throughput bounds for flows with clean channels and long‐term throughput bounds for all
flows with bounded channel error, expanded schedulable region, and support for both delay sensitive and error sensitive data
flows. We present the wireless fair service algorithm, and show through both analysis and simulation that it achieves the
requirements of the service model in typical wireless network environments. The key aspects of the algorithm are the following:
(a) an enhanced fair queueing based service scheme that supports decoupling of delay and bandwidth, (b) graceful service compensation
for lagging flows and graceful service degradation for leading flows, (c) support for real‐time delay sensitive flows as well
as non‐real‐time error sensitive flows, and (d) an implementation within the framework of the simple and robust CSMA/CA wireless
medium access protocol.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
We propose a framework for quality‐of‐service (QoS) provisioning for multimedia services in next generation wireless access
networks. This framework aims at providing a differentiated treatment to multimedia traffic flows at the link layer, which
can be broadly classified as real‐time (or delay‐sensitive) and non‐real‐time (or delay‐tolerant). Various novel schemes are
proposed to support the differential treatment and guarantee QoS. These schemes include bandwidth compaction, channel reservation
and degradation, with the help of which a call admission and control algorithm is developed. The performance of the proposed
framework is captured through analytical modeling and simulation experiments. Analytically, the average carried traffic and
the worst case buffer requirements for real‐time and non‐real‐time calls are estimated. Simulation results show up to 21%
improvement in the admission probability of real‐time calls and up to 17% improvement in the admission probability of non‐real‐time
calls, when various call control techniques like bandwidth compaction are employed. Using our channel reservation technique,
we observe a 12% improvement in the call admission probability compared to another scheme proposed in the literature.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
9.
Two frame‐based ATM scheduling strategies, Delayed Frame Queueing (DFQ) and Virtual Frame Queueing (VFQ), are described for
real‐time network applications. Both strategies guarantee explicit upper bounds on delay and jitter on a per virtual connection
(VC) basis without relying on per‐VC queueing. They also resolve the disadvantages often associated with other frame‐based
schedulers. The DFQ scheduler employs Resource Management cells to enable work‐conserving forwarding at intermediate nodes
while retaining the option for non‐work‐conserving forwarding at terminal nodes. This allows delay bounds to be uncoupled
from jitter bounds. The VFQ scheduler requires no such overhead cell transmissions, but is more limited in its ability to
uncouple these two types of bounds. ATM network simulation results indicate that both proposed disciplines offer favorable
multiplexing performance in comparison to a well documented high performance service discipline. Finally, we contrast our
proposal against the significant difficulties that alternative scheduling strategies based on bandwidth guarantees will face
with regard to network management and network synthesis issues.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
10.
Instead of providing separate solutions for each individual network, a unified theory is desirable to cover the study of a
class of networks. Cartesian product graphs provide a common framework to investigate the performance of several individual
networks. This paper addresses communication capabilities of product networks. Communication cost is generally characterized
by the diameter, the average distance, the total number of paths, the traffic intensity, the saturation level, the queue length
in each node, the communication delay and the network throughput. The diameter and average distance of product networks have
been studied. However, no work has addressed the remaining measures for product networks. This paper presents a unified theory
to evaluate the traffic intensity and the saturation level of product networks. We have theoretically computed the traffic
intensity and the saturation level. Intensive simulations have been conducted to validate the analytical results and to compute
the other measures for different workloads, different networks, and different network sizes. Examples of product networks
that have been investigated are multidimensional meshes, multidimensional toruses, and r‐ary n‐cube networks. We have also shown that the structure (geometry) of a network is a primary factor for network high performance.
For meshes and toruses, square networks present an optimal structure. While in case of an r‐ary n‐cubes, networks with higher radix outperform those with smaller radix. In particular, cross‐cubes (4‐ary n‐cube) are shown to perform better than binary cubes.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
11.
Sivalingam Krishna M. Chen Jyh‐Cheng Agrawal Prathima Srivastava Mani B. 《Wireless Networks》2000,6(1):73-87
This paper describes the design and analysis of a low‐power medium access control (MAC) protocol for wireless/mobile ATM networks.
The protocol – denoted EC‐MAC (energy conserving medium access control) – is designed to support different traffic types with
quality‐of‐service (QoS) provisions. The network is based on the infrastructure model where a base station (BS) serves all
the mobiles currently in its cell. A reservation‐based approach is proposed, with appropriate scheduling of the requests from
the mobiles. This strategy is utilized to accomplish the dual goals of reduced energy consumption and quality of service provision
over wireless links. A priority round robin with dynamic reservation update and error compensation scheduling algorithm is
used to schedule the transmission requests of the mobiles. Discrete‐event simulation has been used to study the performance
of the protocol. A comparison of energy consumption of the EC‐MAC to a number of other protocols is provided. This comparison
indicates the EC‐MAC has, in general, better energy consumption characteristics. Performance analysis of the proposed protocol
with respect to different quality‐of‐service parameters using video, audio and data traffic models is provided.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
12.
Multicasting is a desired function in both wired and wireless networks. Currently, multicasting‐based applications have pervasive
presence and influence in our Internet. Wireless ATM aims to support different traffic types over a high speed wireless network.
In particular, traditional approaches towards multicasting in wired networks cannot be directly applied to mobile ATM networks.
This includes the mechanism proposed to handle mobility in wired networks. In this paper, we address the issues behind multicasting
in wireless ATM networks and the underlying mechanisms to support handoffs of both unicast and multicast connections. Through
simulation, we evaluated the performance of optimal core‐based tree (CBT), late‐joined CBT, optimal source‐based tree (SBT),
and late‐joined SBT during changing multicast host membership conditions. In addition, we evaluated the impact of multicast
receivers' migration on the total link cost of the resultant multicast tree. Simulation results revealed that source‐based
trees incur more total link costs under both dynamic host membership and receivers' migration scenarios. However, it generates
less control messages than the distributed CBT and SBT approaches.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
13.
The major challenges of designing multicast traffic control protocols for a combined wired/wireless network are the varying
transmission characteristics (bandwidth, error, and propagation delay) of the wireless and wired media, and the different,
possibly conflicting frame rate requests from multiple sources. To address these issues, in this paper we design and evaluate
new unicast and multicast guaranteed frame rate (GFR) schemes for supporting TCP/IP traffic over a combined wired/wireless
ATM network. We first propose a new, flexible weighted buffer management, and a frame‐based virtual spacing (VS) mechanism
implementing weighted fair queueing. The unicast GFR scheme is based on the integration of the new weighted buffer management,
and either cell‐based or frame‐based VS. It is then extended to support multicast GFR flows. The multicast scheme presented
in this paper is the first multicast GFR scheme appeared in the literature. These schemes are carefully evaluated over several
network configuration, supporting heterogeneous TCP/IP traffic with various frame rates. Simulation results show that the
new schemes guarantee the minimum rates requested, provide excellent fairness, and achieve reasonably high efficiency. The
new schemes may be extended to provide differentiated service in both IP and mobile IP frame work.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
14.
This paper proposes an architecture design for a tool suitable for emulating DA‐TDMA (demand‐assignment‐time division multiple
access) satellite access schemes. The tool presented, named FRACAS, is particularly suitable for comparing the performance
of different satellite channel allocation policies. Using FRACAS, a service provider can choose from different policies for
sharing a satellite channel among a number of users. Some allocation policies, selected from those available in the literature,
are built‐in, while others can be designed from scratch and added without much effort. The parameters of the built‐in allocation
policies can easily be changed in order to exploit the full potential of the allocation schemes. FRACAS's features permit
the optimisation of satellite resource usage in accordance with the traffic pattern supported. FRACAS enables research teams
and students to explore and compare different multiple access schemes, and to develop simulation runs for various kinds of
service‐induced traffic, including aggregate traffic, which is typical in a local area network (LAN) interconnection environment.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
15.
In this paper, we develop approximation methods to analyze blocking in circuit switched networks with nonstationary call arrival
traffic. We formulate generalizations of the pointwise stationary and modified offered load approximations used for the nonstationary
Erlang loss model or M(t)/M/c/c queue. These approximations reduce the analysis of nonstationary circuit switched networks to solving a small set of simple
differential equations and using the methods for computing the steady state distributions for the stationary versions of such
loss networks. We also discuss how the use of time varying arrival rates literally adds a new dimension to the class of telecommunication
networks we can model. For example, we can model the behavior of alternate routing due to link‐failure, which is a feature
that the classical stationary version of the model cannot capture. Our nonstationary model can also describe aspects of the
dynamic calling traffic behavior arising in cellular mobile traffic. For the special case of a two‐link, three node network,
we present numerical results to compare the various approximation methods to calculations of the exact blocking probabilities.
We also adapt these calculations to approximate the behavior of rerouting calling traffic due to link‐failure. The results
are achieved by formulating some new recursions for evaluating the steady state blocking probabilities of such networks. We
also generalize these techniques to develop analogous formulas for a linear N‐node circuit switched network.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
16.
This paper reports on an analytical study of the performances of the ATM‐ABR service category in transporting TCP/IP flows
over an ATM network. We explore the behavior of a TCP connection over an ATM‐ABR VC, in presence of exogenous non‐controlled
traffic. This fluid analysis of the system allows the study of the interaction between the window‐based end‐to‐end flow control
TCP protocol and the rate‐based flow control ABR mechanism, which is restricted to the ATM part of the network. The main aim
of this study is to give performance evaluation formulae to model the behavior of such a TCP over ABR connection.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
17.
With the combination of telecommunication, entertainment and computer industries, computer networking is adopting a new method
called Asynchronous Transfer Mode (ATM) networking. Congestion control plays an important role in the effective and stable
operation of ATM networks. Traffic management concerns with the design of a set of mechanisms which ensure that the network
bandwidth, buffer and computational resources are efficiently utilized while meeting the various Quality of Service (QoS)
guarantees given to sources as part of a traffic contract. In this paper, the most widely recognized congestion control schemes
for ABR service are investigated. Some of these schemes show either lack of scalability or fairness while other well‐behaved
schemes may require a highly complex switch algorithm that is unsuitable for implementation in cell‐switching high‐speed ATM
networks. A new and improved congestion control scheme is proposed to support the best‐effort ABR traffic. This algorithm
provides the congestion avoidance ability with high throughput and low delay, in addition to achieving the max–min fairness
allocation.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
18.
In recent years, IP networks have become increasingly complex and the range of network applications has widened. As a result,
the need for experimental evaluation of application performance has increased. We introduce a measurement‐based performance
evaluation method that combines a function to generate various patterns of application traffic with one to measure end‐to‐end
network performance at the application level. For our method, we also propose traffic models of various applications that
can represent the characteristics of these applications, for example, the burstiness of traffic. This method has already been
implemented as a benchmarking tool on UNIX operating systems.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
19.
Heo Jeong Won Byun Sung Hyuk Lee Ju Yong Sung Dan Keun Lee Soo Jong 《Telecommunication Systems》2000,14(1-4):291-309
A B‐ISDN national project in Korea has been carried out to develop a National Information Superhighway since 1992. An ATM
switching system has been developed as one of the most important parts in the project, and has been tested in the National
Information Superhighway testbed. In this paper, we develop a cell‐level/call‐level ATM switch simulator using cell‐level
and call‐level input traffic models for evaluating the ATM switching system. The cell‐level simulator models various cell‐level
switching functions such as priority control and multicast, and evaluates the cell‐level performance indices of the ATM switch
in terms of cell delay, throughput, and cell loss probability. On the other hand, the call‐level simulator uses call‐level
traffic models and evaluates the call blocking rate as a call‐level quality of service (QoS).
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
20.
An analytical and simulation performance evaluation is presented for a multi‐access protocol for a data packet radio network
with a limited user capacity. The network employs direct‐sequence code division multiple access (DS‐CDMA) in a centralised
channel load‐sensing scheme with channel overload (collision) detection and blocking via a separate ancillary channel state
information broadcast system. Traffic models that incorporate both a finite population and an infinite population and variable
length data messages are considered. Results show that an improved throughput/delay performance can be obtained by implementing
a channel overload detection (message dropping) scheme as well as a channel overload avoidance (message blocking) scheme.
The channel overload threshold β is fixed at the system's maximum user capacity whereas it is shown that the overload avoidance
blocking threshold α should be variable and dependent on the mean message arrival rate.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献