1,721,091 research outputs found
Improving call admission control procedures by using hand-off rate information
No full textThis paper introduces a general decision model, in the shape of a Markov Decision Process, as an instrument to analytically compare the behavior of call admission control policies. This approach allows the study of a wide class of policies, including well-known pure stationary as well as randomized policies, in a way that explicitly incorporates the dependency between the hand-off rate and the system state, assuming that the hand-off rate arriving to a cell is proportional to the occupancy level of the adjacent cells. In particular, some well-known non-preemptive prioritization schemes are analyzed, including the Cutoff Priority Policy (CPP), which consists of reserving a number of channels for the high priority requests stream. Using our analytical approach, we prove the optimality of CPP within the analyzed class. Copyright © 2001 John Wiley & Sons, Ltd
Call admission control in wireless multimedia networks
No full textThis paper addresses the call admission control problem for the multimedia services that characterize the third generation of wireless networks. In the proposed model each cell has to serve a variety of classes of requests that differ in their traffic parameters, bandwidth requirements and in the priorities while ensuring proper quality of service levels to all of them. A Semi Markov Process is used to model multi-class multimedia systems with heterogeneous traffic behavior, allowing for call transitions among classes. It is shown that the derived optimal policy establishes state-related threshold values for the admission policy of handoff and new calls in the different classes, while minimizing the blocking probabilities of all the classes and prioritizing the handoff requests. It is proven that in restrictive cases the optimal policy has the shape of a Multi-Threshold Priority policy, while in general situations the optimal policy has a more complex shape
End-to-end QoS Framework for Heterogeneous Wired-cum-Wireless Networks
No full textWith information access becoming more and more ubiquitous, there is a need for providing QoS support for communication that spans wired and wireless networks. For the wired side, RSVP/SBM has been widely accepted as a flow reservation scheme in IEEE 802 style LANs. In this paper, we investigate the integration of RSVP and a RSVP-like flow reservation scheme in wireless LANs, as an end-to-end solution for QoS guarantee in wired-cum-wireless networks. We propose WRESV, an RSVP-like flow reservation and admission control scheme for IEEE 802.11 wireless LAN. Using WRESV, wired/wireless integration can be easily implemented by cross-layer interaction at the access point. Main components of the integration are RSVP-WRESV parameter mapping, and the initiation of new reservation messages, depending on where senders/receivers are located. In addition, we also propose various optimizations for supporting multicast session, mobility management, and admission control
A Knowledge Plane for Wireless Mesh Networks
No full textThe quest for the autonomic management of communication systems dates
back to more than two decades ago. In practice, it became a compelling
need when such systems started growing in size and complexity. The risk,
in fact, was that the support/management of the infrastructure became so
expensive to be the major design constraint. In telecommunication networks, in particular, autonomicity is perceived practically as an alias of
Autonomic Network Management (ANM) [1]: proper handling of network
complexity, in fact, is perceived as a cornerstone for achieving robustness
and performance. But, despite the expectations, whileANM is emerging as
one of the hottest research topics, little concrete results have been achieved
so far. This can be ascribed, on one hand, to the complexity of the issue
itself, whose theoretical foundations have not been completed so far, and
on the other one to the lack of a research platform on which novel solutions
can be tested in a controlled and replicable fashion. In such a scenario, due
to their reconfigurability and ease of deployment, wireless mesh networks
provide us the opportunity to design from scratch an autonomic control
plane on top of a network of practical interest. In this paper we propose
a novel Knowledge Plane, tailored specifically for the WMNs scenario
and capable of enabling consistent sharing of services ontology among the
entities participating the WMNs. As a case study, we present JANUS, a
novel and freely available monitoring framework exploiting the proposed
Knowledge Plan
Biological Approach to Autonomic Communication Systems
No full textAmong the most important research topics in computer sciences, a primary role is played by design and control of next-generation communication networks (NGCNs). Such networks will be characterized by heterogeneity at all levels, encompassing a large variety of users, media, processes and channels. Another important feature of NGCNs will be the ability to interact with the environment. Various agents will collect information from the surroundings, and, then take appropriate actions in response, either in a centralized or in a distributed fashion. These features will characterize a pervasive computing and communication environment, a challenging scenario for scientists in all comp-uter sciences-related research fields. Users will be highly mobile, and will need to access services without relying on a end-to-end connection. These factors will reflect into an increasing network management complexity, that will be approaching the limits of human capability.
Consequently, necessary features of NGCNs will be the ability to self-manage, self-adapt and self-organize. These features may be summarized into one single paradigm: autonomic communication (AC). AC is an example where biological systems are considered as models of self-management and self-organization.
This suggests that an appealing approach for governing the complexity of NGCNs is to draw inspiration from biology, as in autonomic computing, in order to achieve an efficient and robust communication system. This requires a multi-disciplinary approach to ICT-related research, which in our view can lead to innovative and creative solutions to the challenges related to next generation networks
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