Vol. 64, No 3-4, March-April 2009
Content available on SpringerLink http://www.springerlink.com/content/0003-4347
Open Topics
A next-generation service overlay architecture
Emmanuel Lavinal1, Noëmie Simoni1, Meng Song2, Bertrand Mathieu2
1 Télécom ParisTech, 46 rue Barrault - 75013 Paris (France)
2 France Télécom R&D, 2 av. Pierre Marzin, 22300 Lannion (France)
Abstract The rapid evolution of next-generation networks and, in particular, fixed mobile convergence infrastructures raises the issue of providing personalized services adapted to the user's context such as its device, access network, preferences, or quality of service (QoS) requirements. To design such value-added services, one solution consists in composing dynamically distributed service entities. In this paper, we propose a service overlay architecture in which a service level path is dynamically established to fulfill the user's requirements. In order to meet this goal, two main issues have to be considered: service components discovery and service path management (i.e., setup, reconfiguration,release). The former issue is addressed based on a peer-to peer approach in which QoS features are integrated in service lookup. For the latter issue, we rely on the Session Initiation Protocol to automate the setup of the service composition as well as its adaptation in case of perturbations (e.g., user switching device or service component failure).
Keywords Next-generation services . QoS-based service discovery . SIP-based service paths
Service business processes for the netx generation of services: a required step to achieve service convergence
Emmanuel Bertin*, Noel Crespi** * Orange Labs, Caen
(France) ** Télécom SudParis,
Evry, France Abstract Users' needs are the driver of
the next generation of telecom services. Founding the services on users' needs requires that
various services cooperate together to meet specific needs. As a consequence,
services should no more be developed as "silo" but with composable service enablers.
This enabler paradigm raises the issues of the identification of the enablers
and of the consistency of a service composed from various enablers. These
issues must be addressed by considering the service from the user point of
view: what is the added value for the user and through which perceived steps is
this added value provided? Such service business processes are then a key tool
to identify enablers and to ensure the coherence of composed service. Keywords NGS . Service enabler .
Business process . Service modeling
WComp middleware for ubiquitous computing: Aspects and composite event-based Web services
Jean-Yves Tigli*, Stéphane Lavirotte*,Gaëtan Rey*,Vincent Hourdin*, Daniel Cheung-Foo-Wo*, Eric Callegari*,Michel Riveill
*Laboratoire I3S, Université de Nice - Sophia Antipolis / CNRS,
Bâtiment Polytech'Sophia - SI 930 route des Colles, B.P. 145, 06903
Sophia-Antipolis Cedex, France Abstract After a survey of the
specific features of ubiquitous computing applications and corresponding
middleware requirements, we list the various paradigms used in the main
middlewares for ubiquitous computing in the literature. We underline the lack
of works introducing the use of the concept of Aspects in middleware dedicated
to ubiquitous computing, in spite of them being used for middleware improvement
in other domains. Then, we introduce our WComp middleware model, which
federates three main paradigms: eventbased Web services, a lightweight
component-based approach to design dynamic composite services, and an adaptation approach
using the original concept called Aspect of Assembly. These paradigms lead to
two ways to dynamically design ubiquitous computing applications. The first
implements a classical component-based compositional approach to design
higher-level composite Web Services and then allow to increment the graph of
cooperating services for the applications. This approach is well suited to
design the applications in a known, common, and usual context. The second way uses
a compositional approach for adaptation using Aspect of Assembly, particularly
well-suited to tune a set of composite services in reaction to a particular variation
of the context or changing preferences of the users. Having detailed Aspect of
Assembly concept, we finally comment on results indicating the expressiveness and
the performance of such an approach, showing empirically that principles of
aspects and program integration can be used to facilitate the design of
adaptive applications. Keywords Ubiquitous computing · Web
services for devices · Event-based
component middleware · Software
composition
TCP throughput guarantee in the DiffServ Assured Forwarding service: what about the results ?
Emmanuel Lochin* · Pascal Anelli** * Université de Toulouse -
LAAS-CNRS - ISAE, Toulouse, France ** Université de la Réunion -
LIM, Saint-Denis Messag, France Abstract Since the proposition of
quality of service (QoS) architectures by the Internet Engineering Task Force
(IETF), the interaction between TCP and the QoS services has been intensively
studied. This paper proposes to look forward to the results obtained in terms
of TCP throughput guarantee in the Diff- Serv assured forwarding (DiffServ/AF)
service and to present an overview of the different proposals to solve the
problem. It has been demonstrated that the standardized IETF DiffServ
conditioners such as the token bucket color marker and the time sliding window color
maker were not good TCP traffic descriptors. Starting with this point, several
propositions have been made, and most of them present new marking schemes in
order to replace or improve the traditional token bucket color marker. The main
problem is that TCP congestion control is not designed to work with the AF
service. Indeed, both mechanisms are antagonists. TCP has the property to share
in a fair manner the bottleneck bandwidth between flows while DiffServ network
provides a level of service that is controllable and predictable. In this
paper, we build a classification of all the propositions made during the past
few years and compare them. As a result, we will see that these conditioning
schemes can be separated into three sets of action levels and that the
conditioning at the network edge level is the most accepted one. We conclude
that the problem is still unsolved and that TCP, conditioned or not
conditioned, remains inappropriate for the DiffServ/AF service. Keywords QoS · End to end guarantee · TCP · DiffServ · Assured forwarding
Quality of service for voice over IP in networks with congestion avoidance
Vitalio A. Reguera* · Evelio M. G. Fernandez** · Felix A. Paliza* · Walter Godoy J***. · Eduardo P. Ribeiro** * Telecommunications
Department, Central University of Las Villas, Santa Clara, Cuba ** Electrical Engineering
Department, Federal University of Parana, Curitiba, Brazil *** Electrical
Engineering Department, Federal University of Technology-Parana, Curitiba,
Brazil Abstract This paper assesses the
impact of active queue management schemes on the quality of service of voice
over Internet protocol applications. A new analytical method based on a fixed
point approach to estimate the end-user satisfaction is proposed. The results obtained
were validated using discrete event simulation techniques. In all the studied
cases, it was observed a great deal of agreement between the analytical results
and the results obtained through simulation. The theoretical predictions, as
well as the presented empirical evidences confirm, as demonstrated in previous
works, that the use of active queue management offers better quality of service
than the traditional queue control mechanisms used in Internet. From these
results, we may reasonably conclude that the presented method can be used for
network design in the presence of voice traffic. Keywords VoIP · Congestion avoidance · AQM · Quality of service · Internet
Internet connection with UMTS
Jahangir Dadkhah
Chimeh*, Mohammad Hakkak** Paeiz Azmi**, Hamidreza
Bakhshi*** * Iran Telecommunication
Research Center, Tehran, Iran ** Tarbiat Modares
University, Tehran, Iran *** Shahed University, Tehran,
Iran Abstract Mobile telecommunication
new services are based on data networks specially Internet. These services
include http, telnet, ftp, Simple Mail Transfer Protocol, etc. Besides, we
recognize a mobile network as a multiuser network. Transmission Control
Protocol (TCP)/Internet Protocol which is sensitive to link congestion in
wireline data links is also used in wireless networks. In order to improve the
system performance, the TCP layer uses flow control and congestion control.
Besides, radio link control (RLC) and medium access control sublayers have been
introduced to compensate the deficiency of TCP layer in wireless environment.
RLC has an important role in quality of service enhancement of the Universal
Mobile Telecommunications System (UMTS). In this paper, we review the protocol
stack of UMTS Terrestrial Radio Access Network which is based on
Third-Generation Partnership Project. Then,
we evaluate its layer 2 error control mechanisms and verify TCP over automatic
repeat request error control mechanism and finally quality of service improvement
results from it in fading channels. Keywords TCP/ARQ
. UTRAN . Fading channel
Some experimental investigation of the effect of railway tunnels on mobile communications in Western India
M. V. S. N. Prasad*, P. K. Dalela** * National Physical
Laboratory, Dr K S Krishnan road, New Delhi 110012, India ** C-DOT, Mandigaon road,
Opp. New Manglapuri, Chatterpur, Mehrauli, New Delhi 110030, India Abstract Establishing of mobile
communications in guided structures like railway tunnels, coal mines, etc., is gaining
increasing importance due to the passage of high speed and high density of
trains in tunnels and for monitoring of information on safety of workers and
dayto- day operations in various mines. The present study reports investigation
of mobile communication experiments in ultra high frequency band in railway
tunnels of western India conducted in a moving train both in uplink and downlink
directions. The observed signal fluctuations are discussed in terms of tunnel
characteristics and different modes of propagation in tunnels and compared with
model deduced values. Keywords Mobile
communications . Path loss measurements .
Tunnels
An efficient receiver scheme for downlink ZP-CDMA
F. S. Al-kamali*, M. I. Dessouky**, & B. M. Sallam**, F. E. Abd El-Samie** * Department of Electronics, Faculty of Engineering, Ibb University,
Ibb, Yemen ** Department of
Electronics and Electrical Communications, Faculty of Electronic Engineering,
Menoufia University, Menouf 32952, Egypt Abstract A signal transmitted
through a wireless channel may be severely distorted by intersymbol
interference (ISI) and multiple access interference (MAI). In this paper, we
propose an efficient CDMA receiver based on frequency domain equalization (FDE)
with a regularized zero forcing (RZF) equalizer and parallel interference cancellation
with a unit clipper decision function (CPIC) to combat both the ISI and the
MAI. We call this receiver the FDE-RZF-CPIC receiver. This receiver is suitable
for downlink zero padding CDMA cellular systems. The effects of the decision
function, the channel estimation, the number of cancelled users, and the user
loading on the performance of the proposed receiver are discussed in the paper.
The bit error rate (BER) of the data received by the proposed receiver is
evaluated by computer simulations. The experimental results show that the
proposed receiver provides a good performance, even with a large number of
interfering users. At a BER of 10-3, the performance gain of the proposed receiver is
about 2 dB over the RAKE receiver with a clipper decision function and PIC in
the half-loaded case (eight users) and is much larger in the full-loaded case
(16 users). Keywords Downlink CDMA . Decision functions
. PIC . Zero padding . Channel estimation
