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Dynamic link asymmetry in `bunched' wireless networks.
KTH, Superseded Departments, Signals, Sensors and Systems.
KTH, Superseded Departments, Signals, Sensors and Systems.ORCID iD: 0000-0003-4986-6123
1999 (English)In: Vehicular Technology Conference, 1999. VTC 1999 - Fall. IEEE VTS 50th, 1999, 352-356 p.Conference paper (Refereed)
Abstract [en]

In most future wireless applications an increasing fraction of the total offered traffic is expected to appear in the downlink (fixed-to-mobile) segment of the system. This requirement matches rather poorly with the system design and spectrum allocation for current and future systems which employ symmetric frequency division duplex (FDD). In contrast, TDMA/TDD systems, at least in principle, allow for a more flexible resource allocation by moving the boundary between uplink and downlink time-slots, the switching point. The key problem caused by moving the switching point; is interference between mobiles and base stations. In the paper, some algorithms to select and adapt the switching point in a `bunched' cellular environment are investigated. A simple scheme using a `soft' switching point, is shown to provide a capacity, while not as high as a fully dynamic scheme, still considerably higher than the capacity of a traditional fixed switching point scheme. Further, the `soft' scheme is also adaptive, in the sense that it tracks varying traffic asymmetry ratios.

Place, publisher, year, edition, pages
1999. 352-356 p.
Keyword [en]
cellular radio, time division multiple access, time division multiplexing
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
URN: urn:nbn:se:kth:diva-25405DOI: 10.1109/VETECF.1999.797155OAI: diva2:357981
IEEE VTS 50th, 19 sep 1999 - 22 sep 1999, Amsterdam
QC 20101020Available from: 2010-10-20 Created: 2010-10-20 Last updated: 2010-10-21Bibliographically approved
In thesis
1. Demand responsive resource management for cellular networks: link asymmetry, pricing and multihopping
Open this publication in new window or tab >>Demand responsive resource management for cellular networks: link asymmetry, pricing and multihopping
2005 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Economic affordability of services and infrastructures has rapidly become one of the key issues in the evaluation and design of wireless access systems. The provisioning of high data rates, at an ``affordable'' price, constitutes a serious challenge to the structure and management of current and future wireless networks.

The management of radio resources, Radio Resource Management or RRM for short, has traditionally been benchmarked mostly by technical merits such as throughput (data delivery capability) and Quality of Service (QoS). When comparing different RRM schemes, the scheme that can deliver more bits per Hertz (unit of bandwidth) or per Euro is often assumed the more efficient. From an economic point of view, however, cost efficiency is not equivalent to profitability.

We conjecture that the economic efficiency and profitability can be improved both by better technical efficiency and by better accounting for users' service appreciation and willingness to pay. While we shall, primarily treat the operator's benefit of improved RRM, we will try to improve the RRM by means of being more responsive to the demands of the users. In eight conference and journal papers, we investigate: Provisioning of support for asymmetric traffic, Quality and pricing aware resource management and Creation of forwarding incentive in multihop cellular networks.

We show that implementing support for asymmetric links can improve the efficiency of (service) production in Time Division Duplexing (TDD) mode wireless networks with asymmetric traffic. That is, more traffic can be handled with the same system resources. Compared to Frequency Division Duplexing (FDD), TDD offers more flexible use of spectrum resources. The benefits of TDD and support for asymmetric links are readily available for systems providing high-rate spotty coverage. For systems aiming at full coverage and tight reuse, however, proper measures must be taken to control inter-mobile- and inter-base-station-interference.

We present the MEDUSA model framework for taking users' service appreciation and willingness to pay into account in performance evaluations of wireless networks with elastic traffic. Assuming that user satisfaction depends on both the quality and the price of the service, numerical experiments show that the economic efficiency of an RRM scheme is affected by the pricing scheme. We also introduce the concepts of speculative resource management to exploit traffic elasticity and improve resource utilisation. With speculative admission control, users with good propagation conditions may be admitted to a full system at the expense of a slight degradation of the QoS of some or all users, if the expected total revenue would thereby increase. Results indicate significant revenue gain with speculative admission control. Service perception aware scheduling was evaluated as a means to improve resource utilisation, but yielded only marginal gain compared to a weighted proportional fair scheduler.

For the third area studied in this Thesis, i.e. multihopping in cellular networks, economic efficiency was both the goal and one of the means to achieve it. By means of a resource re-distribution scheme called Resource Delegation we eliminated the bandwidth bottle neck of the relays. We combined Resource Delegation with economic compensation for the energy expenditures of the relays and were able to achieve significantly increased operator revenue with maintained or improved user utility. Assuming that the added complexity of keeping track of reward transactions is negligible, profitability was correspondingly improved.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. viii, 90 p.
Trita-S3-RST, ISSN 1400-9137 ; 0509
Electrical engineering, Elektroteknik, elektronik och fotonik
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
urn:nbn:se:kth:diva-180 (URN)
Public defence
2005-04-29, Sal C1, Electrum, Isafjordsgatan 22, Kista, 14:00
QC 20101021Available from: 2005-04-27 Created: 2005-04-27 Last updated: 2010-10-21Bibliographically approved

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