Resourse Allocation in Multi-Service Wireless Access Network
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Date
2007
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Publisher
UMT.Lahore
Abstract
Wireless Access Networks offer an alternative method for connecting subscribers to the
global telecommunication networks. They will become widespread only if they can
provide an attractive set of communication services at competitive prices and quality.
Fundamental to achieving these goals is how the scarce radio frequency is managed. We
evaluate a few alternative resource management principles and highlight some key design
issues for such networks. The emphasis is on providing services that require certain
minimum performance guarantees in order to be useful. High quality communication
services and efficient resource management is only possible if the resource requirements
of different services can be adequately described. We propose a framework for
expressing wireless communication services in terms upon which radio resource
management algorithms can operate. A price/priority component can be used to prioritize
between different services. A comparison is made between fixed (PCA) and dynamic
(DCA) channel allocation for multi-service TDMA networks. We show that if access
networks should be capable of offering high peak-rate services, i.e., requiring more than a
few percent of the available frequency spectrum, dynamic channel allocation techniques
seem an imperative design component.
Applications that can adapt to varying service levels enable higher resource utilization.
The resulting admission control problem is formulated as a flexible knapsack problem. A
few simple service-pricing models illustrate some tradeoffs involved in defining and
pricing new services. Distributed quality-based power control has previously been shown
to achieve substantial quality and capacity gains over a constant transmitter power
scheme. We compare two classes of quality based power control, differentiated by the
rate of the feedback information. A slow power control is preferable when the radio
environment changes fast or coding and interleaving can be used to compensate for
multi-path fading degradations. A fast scheme is preferred when communication links are
established for only short periods, such as when providing busty data services, and for
slowly moving terminals. A new technique is also developed to decrease the transmitter
power dynamic range when using fast step-wise quality based power control.
We demonstrate that with a suitable set of channel selection and channel access
procedures, services for moderately busty data users can be provided without unduly
degrading the quality of real-time services. This is possible without splitting of the
available frequency resource between different user classes. A novel method is developed
to "prepare" channels for rapid channel reassignments. Further, a traffic model for WWW
and distributed file system access over wireless links is derived, based on an analysis of