O crescente aumento da demanda de tráfego nas redes celulares vem aumentando a necessidade de uma melhor utilização dos recursos do sistema, já que sua expansão é custosa. Nas estações rádio base (ERB), a disponibilidade de largura de faixa de freqüências é limitada e desta maneira, em uma rede de comunicação móvel celular, o controle de admissão de chamadas exerce grande influência no desempenho do sistema, pois determina a utilização de banda das ERBs e se uma determinada quantidade de recursos (banda) será alocado ou não para uma determinada chamada. O desempenho da rede pode ser atrelado a determinados parâmetros, como a probabilidade de bloqueio de novas chamadas, probabilidade de bloqueio de chamadas handoff e a utilização de banda da rede. Este trabalho propõe um controle de admissão de chamadas que, no atendimento de uma chamada, faz o empréstimo de banda de chamadas em andamento na célula no caso de banda insuficiente. O sistema adota um mecanismo heurístico que determina a banda disponível para novas chamadas conforme os valores de certos parâmetros do sistema. O empréstimo de banda é realizado em chamadas em andamento nas células até níveis mínimos estabelecidos para cada tipo de chamada...
A tecnologia WDM (Wavelength Division Multiplexing) e a introdução de OXCs (Optical Cross Connect) e OADMs (Optical Add/Drop Multiplexer) puramente ópticos podem dotar as redes ópticas da função de networking, ou seja, da capacidade de manipular comprimentos de onda de forma a implementar o roteamento destes. Esta possibilidade implica em uma nova forma de relacionamento das aplicações com a camada física, sendo a arquitetura GMPLS candidata a estabelecer tal relacionamento. Soluções eficientes para o problema de alocação de recursos e roteamento de tráfego tornam-se uma necessidade imperiosa em projeto, expansão e gerenciamento de redes ópticas. A contribuição desta tese consiste em relacionar funcionalidades tais como: agregação (grooming) de tráfego, mecanismo de controle de admissão de chamadas (CAC), mecanismos de restauração e alocação de conversores em redes ópticas heterogêneas, avaliando-se as métricas de probabilidade de bloqueio, probabilidade do tráfego bloqueado e imparcialidade (fairness). Tais funcionalidades são tratadas separadamente na literatura. Com este objetivo em mente modela-se a rede com duas camadas: a camada física e a camada virtual. Estabelecem-se duas políticas de agregação de tráfego MrTV (minimização da rota na topologia virtual) e MrTF (minimização da rota na topologia física) e analisa-se o desempenho destas em relação à porcentagem de tráfego bloqueado. Em seguida um mecanismo de controle de admissão de chamadas (CAC) é implementado e sua influência em termos de imparcialidade (fairness) e probabilidade de bloqueio é analisada. A simulação e análise de redes ópticas...
Nesta dissertação se propõe um método de controle de admissão de chamadas fuzzy (FCAC) e um método de controle de fluxo fuzzy (FFC), considerando tráfegos multiclasses. Ambos métodos trabalham em conjunto e são implementados na interface aérea das redes 3G UMTS. O método FCAC aceita ou rejeita a requisição de uma nova chamada considerando a prioridade de cada classe de tráfego, assim como a banda efetiva total disponível na interface aérea. Devido a natureza de controle fuzzy, o método FCAC-FFC proposto é considerado como um método de bloqueio gradual. Os usuários de menor prioridade serão sempre os primeiros a serem bloqueados se a banda efetiva total disponível não for suficiente. O método FFC reduz a taxa de transmissão dos usuários ativos de menor prioridade caso seja necessário e, como consequência, a banda efetiva disponível aumenta. Desta forma, temos um uso mais eficiente dos recursos do sistema incrementando o número médio de usuários ativos. O método proposto foi implementado no ambiente de simulação MATLAB e foi utilizada a toolbox de lógica fuzzy para projetar os controladores fuzzy. Os resultados da simulação mostram que o esquema de controle de admissão proposto garante o uso eficiente dos recursos da interface aérea e obtém um melhor desempenho em comparação com os esquemas CAC-FC e FCAC-FC analisados...
The resource allocation in the Broadband Integrated Services Digital Network (B-ISDN) can be based in an overall network performance function described in this paper and named quality of operation.
The quality of operation function is determined itself by bandwidth and quality of service functions.
The traffic patterns of the quality of service for each call are predicted by neural networks.
The applicability of the quality of operation function to connection admission control and call routing is proposed and supported by simulation results.
This paper discusses a technique for call admission and routing control, based on a global quality function, which is dependent on the allocated bandwidth, the free network capacity and the call rejection rate, and incorporates quality of service functions, predicted by neural networks. The superior capability of this technique to support admission and routing decisions, according to the characteristics of the traffic generated by admitted calls, is demonstrated by simulation results carried out using suitable traffic and network models, which are equally discussed.
It is also shown that the proposed technique, being based on several observed traffic parameters, offers better results than methods based only on declared bandwidth parameters.
http://wts2010.eng.usf.edu/; In NGN service-provisioning platforms the existence of an efficient and flexible admission control mechanism is essential for providing quality of service in a reliable and stable way, avoiding congestion scenarios caused by indiscriminate and uncontrolled service requests. The capability of modulating and regulating the rate of call acceptance, and provide service differentiation allow indirect control of the load submitted to the platform. This paper presents a service admission control solution that enables to differentiate, limit and modulate the rate by which service requests are submitted into a NGN service-provisioning platform. The solution is focused on providing a fair level of bandwidth sharing among service classes, in a configurable and dynamic way so that it can adapt the distribution by which service requests are served. To sustain the design goals of our solution, major scheduling disciplines and rate control mechanisms are here studied and compared in order to elect the more adequate components. The implemented solution was submitted to unit and charge tests; the results show its effectiveness and robustness in controlling and differentiating incoming service calls.
In real-time service provisioning platforms the existence of an efficient and flexible admission control mechanism is essential for providing quality of service in a reliable and stable way, avoiding congestion scenarios caused by indiscriminate and uncontrolled service request admission. The capability of modeling and regulating the rate of call acceptance, and provide service differentiation allow indirect control of the load submitted to the platform. This paper presents a service differentiated admission control solution that allows to limit and modulate the rate by which service requests are submitted into a service provisioning platform. The solution is focused on providing a fair level of bandwidth sharing among service classes, in a configurable and dynamic way so that it can adapt the distribution by which service requests are served. To sustain the design decisions of our solution, major scheduling disciplines and rate control mechanisms, some of them proposed recently, are studied and compared. The solution was submitted to unit and charge tests, whose results show its effectiveness and robustness.
PhD Thesis; In this thesis we developed a resource allocation framework for wireless code division multiple access (CDMA) networks that support multi-class traffic with different data rates and bit error rate requirements. We proposed a new resource allocation scheme using joint adaptive power control and antenna array multiuser receiver in multipath fading system. In this scheme both transmit power and receiver filter adapt to time- varying fading channel state. By dynamically assigning users appropriate transmit power and receiver filter, the scheme can guarantee users' diverse quality of service (QoS) requirements and significantly improve quality and capacity of the system. We derived theory for abstraction of bandwidth resource and characterization of system capacity for multi-class traffic in multipath fading system. Bandwidth resource allocated to a user can be abstracted as "effective bandwidth", determined by the user's source data rate and target bit error rate. Capacity inmultipath fading system can be characterized by a theoretical bound. Simulations show that actual system capacity in multipath fading environment is close to the theoretical bound at large power constraint. The multirate multiuser receiver can achieve significantly larger capacity for users with higher source data rate and lower target bit error rate than conventional matched-filter receiver. The antenna array multiuser receiver can provide large capacity for users with higher signal-to-interference ratio requirement and achieve high bandwidth utility at lower power constraints. We also proposed a new call admission control scheme for CDMA cellular system that incorporates adaptive power control and antenna array multiuser receiver and supports multi-class traffic. The scheme is based on estimation of othercell interferenceand implemented distributively in each cell. The scheme can adapt to various traffic distribution. Capacity determined by the admission control agrees well with the actual system capacity in the simulation. The scheme can achieve high bandwidth utilization and guarantee QoS requirements of all the users.; Texas Advanced Technology Program; Nokia; National Science Foundation
One of the enabling technologies for Long Term Evolution (LTE) deployments is the
femtocell technology. By having femtocells deployed indoors and closer to the user,
high data rate services can be provided efficiently. These femtocells are expected
to be depolyed in large numbers which raises many technical challenges including
the handover management. In fact, managing handovers in femtocell environments,
with the conventional manual adjustment techniques, is almost impossible to keep
pace with in such a rapidly growing femtocell environment. Therefore, doing this
automatically by implementing Self Organizing Network (SON) use cases becomes a
necessity rather than an option. However, having multiple SON use cases operating
simultaneously with a shared objective could cause them to interact either negatively
or positively. In both cases, designing a suitable coordination policy is critical in
solving negative conflicts and building upon positive benefits.
In this work, we focus on studying the interactions between three self optimization
use cases aiming at improving the overall handover procedure in LTE femtocell
networks. These self optimization use cases are handover, Call Admission Control
(CAC) and load balancing. We develop a comprehensive...
To meet growing demand for wireless access to multimedia traffic, future generations of wireless networks need to provide heterogenous services with high data rate and guaranteed quality-of-service (QoS). Many enabling technologies to ensure QoS
have been investigated, including cross-layer admission control (AC), error control and congestion control.
In this thesis, we study the cross-layer AC problem. While previous research focuses on single-antenna systems, which does not
capitalize on the significant benefits provided by multiple antenna
systems, in this thesis we investigate cross-layer AC policy for a code-division-multiple-access (CDMA) system with antenna arrays at the base station (BS). Automatic retransmission request (ARQ)
schemes are also exploited to further improve the spectral efficiency.
In the first part, a circuit-switched network is considered and an exact outage probability is developed, which is then employed to derive the optimal call admission control (CAC) policy by formulating a constrained semi-Markov decision process (SMDP). The derived optimal policy can maximize the system throughput with
guaranteed QoS requirements in both physical and network layers.
In the second part, a suboptimal low-complexity CAC policy is
proposed based on an approximate power control feasibility condition (PCFC) and a reduced-outage-probability algorithm. Comparison between optimal and suboptimal CAC policies shows that the suboptimal CAC policy can significantly reduce the computational
complexity at a cost of degraded performance.
In the third part...
Depuis quelques années, la recherche dans le domaine des réseaux maillés sans fil ("Wireless Mesh Network (WMN)" en anglais) suscite un grand intérêt auprès de la communauté des chercheurs en télécommunications. Ceci est dû aux nombreux avantages que la technologie WMN offre, telles que l'installation facile et peu coûteuse, la connectivité fiable et l'interopérabilité flexible avec d'autres réseaux existants (réseaux Wi-Fi, réseaux WiMax, réseaux cellulaires, réseaux de capteurs, etc.). Cependant, plusieurs problèmes restent encore à résoudre comme le passage à l'échelle, la sécurité, la qualité de service (QdS), la gestion des ressources, etc. Ces problèmes persistent pour les WMNs, d'autant plus que le nombre des utilisateurs va en se multipliant. Il faut donc penser à améliorer les protocoles existants ou à en concevoir de nouveaux.
L'objectif de notre recherche est de résoudre certaines des limitations rencontrées à l'heure actuelle dans les WMNs et d'améliorer la QdS des applications multimédia temps-réel (par exemple, la voix). Le travail de recherche de cette thèse sera divisé essentiellement en trois principaux volets: le contrôle d‟admission du trafic, la différentiation du trafic et la réaffectation adaptative des canaux lors de la présence du trafic en relève ("handoff" en anglais).
Dans le premier volet...
The Call admission control (CAC) is one of the Radio Resource Management
(RRM) techniques plays instrumental role in ensuring the desired Quality of
Service (QoS) to the users working on different applications which have
diversified nature of QoS requirements. This paper proposes a fuzzy neural
approach for call admission control in a multi class traffic based Next
Generation Wireless Networks (NGWN). The proposed Fuzzy Neural Call Admission
Control (FNCAC) scheme is an integrated CAC module that combines the linguistic
control capabilities of the fuzzy logic controller and the learning
capabilities of the neural networks .The model is based on Recurrent Radial
Basis Function Networks (RRBFN) which have better learning and adaptability
that can be used to develop the intelligent system to handle the incoming
traffic in the heterogeneous network environment. The proposed FNCAC can
achieve reduced call blocking probability keeping the resource utilisation at
an optimal level. In the proposed algorithm we have considered three classes of
traffic having different QoS requirements. We have considered the heterogeneous
network environment which can effectively handle this traffic. The traffic
classes taken for the study are Conversational traffic...
Provisioning of Quality of Service (QoS) is a key issue in any multi-media
system. However, in wireless systems, supporting QoS requirements of different
traffic types is more challenging due to the need to minimize two performance
metrics - the probability of dropping a handover call and the probability of
blocking a new call. Since QoS requirements are not as stringent for
non-real-time traffic types, as opposed to real-time traffic, more calls can be
accommodated by releasing some bandwidth from the already admitted
non-real-time traffic calls. If we require that such a released bandwidth to
accept a handover call ought to be larger than the bandwidth to accept a new
call, then the resulting probability of dropping a handover call will be
smaller than the probability of blocking a new call. In this paper we propose
an efficient Call Admission Control (CAC) that relies on adaptive multi-level
bandwidth-allocation scheme for non-real-time calls. The scheme allows
reduction of the call dropping probability along with increase of the bandwidth
utilization. The numerical results show that the proposed scheme is capable of
attaining negligible handover call dropping probability without sacrificing
The Call admission control (CAC) is one of the Radio Resource Management
(RRM) techniques that plays influential role in ensuring the desired Quality of
Service (QoS) to the users and applications in next generation networks. This
paper proposes a fuzzy neural approach for making the call admission control
decision in multi class traffic based Next Generation Wireless Networks (NGWN).
The proposed Fuzzy Neural call admission control (FNCAC) scheme is an
integrated CAC module that combines the linguistic control capabilities of the
fuzzy logic controller and the learning capabilities of the neural networks.
The model is based on recurrent radial basis function networks which have
better learning and adaptability that can be used to develop intelligent system
to handle the incoming traffic in an heterogeneous network environment. The
simulation results are optimistic and indicates that the proposed FNCAC
algorithm performs better than the other two methods and the call blocking
probability is minimal when compared to other two methods.; Comment: International Journal of Computer Science Issues online at
The Next Generation Wireless Networks (NGWN) will be heterogeneous in nature
where the different Radio Access Technologies (RATs) operate together .The
mobile terminals operating in this heterogeneous environment will have
different QoS requirements to be handled by the system. These QoS requirements
are determined by a set of QoS parameters. The radio resource management is one
of the key challenges in NGWN. Call admission control is one of the radio
resource management technique plays instrumental role in ensure the desired QoS
to the users working on different applications which have diversified QoS
requirements from the wireless networks . The call blocking probability is one
such QoS parameter for the wireless network. For better QoS it is desirable to
reduce the call blocking probability. In this customary scenario it is highly
desirable to obtain analytic Performance model. In this paper we propose a
higher order Markov chain based performance model for call admission control in
a heterogeneous wireless network environment. In the proposed algorithm we have
considered three classes of traffic having different QoS requirements and we
have considered the heterogeneous network environment which includes the RATs
that can effectively handle applications like voice calls...
To address network congestion stemmed from traffic generated by advanced user
equipments, in  we propose a novel network resource allocation strategy,
time-frequency resource conversion (TFRC), via exploiting user behavior, a
specific kind of context information. Considering an LTE-type cellular network,
a call admission control policy called double-threshold guard channel policy is
proposed there to facilitate the implementation of TFRC. In this report, we
present state transition analysis of this TFRC-based call admission control
policy for an LTE-type cellular network. Overall, there are five categories of
events that can trigger a transition of the system state: 1) a new call
arrival; 2) a handoff user arrival; 3) a handoff user departure; 4) a call
termination; and 5) a periodic time-frequency resource conversion. We analyze
them case by case in this report and the validation of the analysis has been
provided in .; Comment: 10 pages
We examine the problem of accepting a new request for a pre-stored VBR video
stream that has been smoothed using any of the smoothing algorithms found in
the literature. The output of these algorithms is a piecewise constant-rate
schedule for a Variable Bit-Rate (VBR) stream. The schedule guarantees that the
decoder buffer does not overflow or underflow. The problem addressed in this
paper is the determination of the minimal time displacement of each new
requested VBR stream so that it can be accomodated by the network and/or the
video server without overbooking the committed traffic. We prove that this
call-admission control problem for multiple requested VBR streams is
NP-complete and inapproximable within a constant factor, by reducing it from
the VERTEX COLOR problem. We also present a deterministic morphology-sensitive
algorithm that calculates the minimal time displacement of a VBR stream
request. The complexity of the proposed algorithm make it suitable for
real-time determination of the time displacement parameter during the call
admission phase.; Comment: 12 pages, 9 figures, includes appendix
The increasing demand for advanced services in wireless networks raises the
problem for quality of service (QoS) provisioning with proper resource
management. In this research, such a provisioning technique for wireless
networks is performed by Call Admission Control (CAC). A new approach in CAC
named by Uniform Fractional Band (UFB) is proposed in this work for the
wireless networks for providing proper priority between new calls and handover
calls. This UFB scheme is basically a new style of handover priority scheme.
Handover priority is provided by two stages in this scheme which help the
network to utilize more resources. In addition, the handover call rate
estimation and its impact on QoS provisioning is discussed widely to attain the
optimum QoS in proposed handover priority scheme. In multiple services
providing wireless network, excessive call blocking of lower priority traffic
is very often event at very high traffic rate which is a concerning issue for
QoS provisioning. To attain such QoS provisioning for multiple services,
another CAC scheme is proposed in this research work. This scheme is recognized
by Uniform Band Thinning (UBT) scheme which is based on uniform thinning
technique (UTT) and this is quite similar idea as UFB scheme. In this scheme...
Due to the fact that Quality of Service (QoS) requirements are not as
stringent for non-real-time traffic types, as opposed to real-time traffic,
more calls can be accommodated by releasing some bandwidth from the existing
non-real-time traffic calls. If the released bandwidth to accept a handover
call is larger than to accept a new call, then the probability of dropping a
call is smaller than the probability of blocking a call. In this paper we
propose an efficient Call Admission Control (CAC) that relies on adaptive
multi-level bandwidth-allocation scheme for non-real-time calls. The features
of the scheme allow reduction of the call dropping probability along with the
increase of the bandwidth utilization. The numerical results show that the
proposed scheme is able to attain negligible handover call dropping probability
without sacrificing bandwidth utilization.; Comment: International Conference on ICT Convergence (ICTC), Nov. 2010, Jeju,
The provision of multiclass services is gaining wide
acceptance and will be more ubiquitous in future wireless and mobile
systems. The crucial issue is to provide the guaranteed mobile
quality of service (QoS) for arriving multiclass calls. In multimedia
cellular networks, we should not only minimize the dropping rate
of handoff calls, but also control the blocking rate of new calls at
an acceptable level. This paper proposes a novel multiclass call-admission-
control mechanism that is based on a dynamic reservation
pool for handoff requests. In this paper, we propose the concept
of servicing multiclass connections based on priority determination
through the combined analysis of mobile movement information
and the desired QoS requirements of multimedia traffic. A
practical framework is provided to determine the occurrence time
of handoff-request reservations. In our simulation experiments,
three kinds of timers are introduced for controlling the progress
of discrete events. Our simulation results show that the individual
QoS criteria of multiclass traffic such as the handoff call-dropping
probability can be achieved within a targeted objective and the
new-call-blocking probability is constrained to be below a given
level. The proposed scheme is applicable to channel allocation of
multiclass calls over high-speed wireless multimedia networks