| 1. |
- Agrawal, P, et al.
(författare)
-
Multimedia multicast/broadcast services in 3G/4G networks
- 2004
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Ingår i: IEEE Communications Magazine. - : Institute of Electrical and Electronics Engineers (IEEE). - 0163-6804 .- 1558-1896. ; 42:2, s. 62-63
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 2. |
- Ahlin, Lars, et al.
(författare)
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Automous tactical communication : problems & possibilities
- 1996
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Konferensbidrag (refereegranskat)abstract
- On the battlefield of the future, more and more information will be available for making decisions on a tactical level, provided that this information can be dispersed rapidly and accurately. Sophisticated electronic equipment for communication, information processing and for collection of sensor data are becoming light-weight, small and inexpensive. As a consequence, advanced tactical decision support that now is limited to advanced platforms (e.g. combat aircrafts) will become available at a much lower level, maybe down to the individual soldier. In such a scenario, the number of communicating entities is one or several orders of magnitude larger than in todays tactical systems. Establishing reliable wireless communications in such a large group constitutes a considerable engineering challenge. In this paper we investigate the specific engineering challenges and the fundamental limitations of such low level, autonomous communication systems. Our conclusions are that mainly distributed computing complexity, device power consumption and available bandwidth constitute the fundamental problems.
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| 3. |
- Ahlin, Lars, et al.
(författare)
-
Automous Tactical Communications Possibilities and Problems
- 1997
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Ingår i: MILCOM 97 Proceedings. - 0780342496 ; , s. 393-397
-
Konferensbidrag (refereegranskat)abstract
- In the battlefield of the future, more and more information will be available for making decisions on a tactical level, provided that this information can be dispersed rapidly and accurately. As a consequence, advanced tactical decision support that now is limited to advanced platforms (e.g. combat aircrafts) will become available at a much lower level, ranging from different kinds of vehicles, down to the individual soldier by means of ultra-light weight ``wearable'' equipment. Establishing reliable wireless communications in such a large group of users with unprecidented bandwidth demands and requirements on survivability constitutes a considerable enginerring challenge. In the paper we will, after a short review of some existing approaches, investigate the specific engineering challenges and the fundamental limitations of such low level, autonomous communication systems. Further we give an example of a system architecture, harmonized with a proposed structure for third generation commercial wireless systems (e.g. UMTS). Our conclusions show that mainly distributed computing complexity, device power consumption and available bandwidth constitute the fundamental problems.
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| 4. |
- Ahlin, Lars, et al.
(författare)
-
Principles of Wireless Communications
- 2006
-
Bok (refereegranskat)abstract
- This textbook provides the reader with a basic understanding of the design and analysis of wireless and mobile communication systems. It deals with the most important techniques, models and tools used today in the design of mobile wireless links and gives an introduction to the design of wireless networks. Topics covered include: fundamentals of radio propagation and antennas; transmission schemes, including modulation, coding and equalising schemes for broadband wireless communications; diversity systems; wireless data transmission; introduction to Wireless Network design and resource management. The fundamentals are illustrated by examples from state-of-the-art technologies such as OFDM, WCDMA, WLANs and others. The book contains a significant number of worked examples and more than 160 problems with answers. It is intended for use in a first graduate course in wireless communications and the reader should be familiar with the fundamentals of probability and communication theory.
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| 5. |
- Ahmed, Ashraf Awadelkarim Widaa
(författare)
-
Towards Affordable Provisioning Strategies for Local Mobile Services in Dense Urban Areas : A Techno-economic Study
- 2017
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The future mobile communication networks are expected to cope with growing local usage patterns especially in dense urban areas at more affordable deployment and operation expenses. Beyond leveraging small cell architectures and advanced radio access technologies; more radio spectrum are expected to be required to achieve the desired techno-economic targets. Therefore, the research activity has been directed towards discussing the benefits and needs for more flexible and local spectrum authorization schemes. This thesis work is meant to be a contribution to this ongoing discussion from a techno-economic perspective. In chapter three, the engineering value of the different flexible authorization options are evaluated from the perspective of established mobile network operators using the opportunity cost approach. The main results in chapter three indicate the economic incentives to deploy more small cells based on flexible spectrum authorization options are subject to the potential saving in the deployment and operation costs. Nonetheless; high engineering value can be anticipated when the density of small cells is equal or larger than the active mobile subscribers’ density. While in chapter four, the possible local business models around different flexible authorization options are investigated from the perspective of emerging actors with limited or ’no’ licensed spectrum resources. In this context, dependent or independent local business can be identified according to surrounding spectrum regulations. On possible independent local business models for those emerging actors is to exploit the different flexible spectrum authorization options to provision tailored local mobile services. Other viable dependent local business models rest with the possibility to enter into different cooperation agreements to deploy and operate dedicated local mobile infrastructure on behalf established mobile network operators.
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| 6. |
- Anderlind, Erik, et al.
(författare)
-
A Traffic Model for Non-Real-Time Data Users in Wireless Radio Networks
- 1997
-
Ingår i: IEEE Communications Letters. - : IEEE. - 1089-7798 .- 1558-2558. ; 1:2, s. 37-39
-
Tidskriftsartikel (refereegranskat)abstract
- Based on an analysis of Internet protocols for data communication, we propose a simple model for future data traffic in wireless radio networks. Model parameters are selected so as to resemble traffic from the Worldwide Web (WWW) access and from distributed file systems. By changing a single parameter, the model can be switched between resembling up- or down-link traffic. The model is intended for design and performance analysis of radio resource allocation algorithms in future wireless systems.
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| 7. |
- Andersin, Michael, et al.
(författare)
-
Distributed Discrete Power Control in Cellular PCS
- 1998
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Ingår i: Wireless personal communications. - : Springer. - 0929-6212 .- 1572-834X. ; 6:3, s. 211-213
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Tidskriftsartikel (refereegranskat)abstract
- Transmitter power control has proven to be an efficient method to control cochannel interference in cellular PCS, and to increase bandwidth utilization. Power control can also improve channel quality, lower the power consumption, and facilitate network management functions such as mobile removals, hand-off and admission control. Most of the previous studies have assumed that the transmitter power level is controlled in a continuous domain, whereas in digitally power controlled systems, power levels are discrete. In this paper we study the transmitter power control problem using only a finite set of discrete power levels. The optimal discrete power vector is characterized, and a Distributed Discrete Power Control (DDPC) algorithm which converges to it, is presented. The impact of the power level grid on the outage probability is also investigated. A microcellular case study is used to evaluate the outage probabilities of the algorithms.<
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| 8. |
- Andersin, Michael, et al.
(författare)
-
Gradual removals in cellular PCS with constrained power control and noise
- 1995
-
Ingår i: IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC. - 0780330021 ; , s. 56-60
-
Konferensbidrag (refereegranskat)abstract
- In this paper we study the mobile removal problem in a cellular PCS network where transmitter powers are constrained and controlled by a distributed constrained power control (DCPC) algorithm. Due to transmitter mobility and random signal propagation, there are system states where not all transmitters can be supported, even under the optimal power control. Thus, some of them should be removed. It can be shown that finding the optimal removal set is an NP-complete problem, and therefore gives rise to heuristic algorithms. In this paper we study and compare among three classes of transmitter removal algorithms, one-by-one removals, multiple removals and power control with removals combined. All removal algorithms are compared with respect to their outage probabilities and their time to convergence to a steady state. The power control with removals combined algorithm emerges as the best approach with respect to both criteria.
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| 9. |
- Andersin, Michael, et al.
(författare)
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Gradual Removals in Cellular PCS with Constrained Power Control and Noise
- 1996
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Ingår i: Wireless networks. - : Kluwer Academic Publishers. - 1022-0038 .- 1572-8196. ; 2:1, s. 27-43
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper we study the mobile removal problem in a cellular PCS network where transmitter powers are constrained and controlled by a Distributed Constrained Power Control (DCPC) algorithm. Receivers are subject to nonÂnegligible noise, and the DCPC attempts to bring each receiver's CIR above a given target. To evaluate feasibility and computational complexity, we assume a paradigm where radio bandwidth is scarce and interÂbase station connection is fast. We show that finding the optimal removal set is an NP-Complete problem, giving rise for heuristic algorithms. We study and compare among three classes of transmitter removal algorithms. Two classes consist of algorithms which are invoked only when reaching a stable power vector under DCPC. The third class consist of algorithms which combine transmitter removals with power control. These are One-by-one Removals, Multiple Removals, and Power Control with Removals Combined. In the class of power control with removals combined, we also consider a distributed algorithm which uses the same local information as DCPC does. All removal algorithms are compared with respect to their outage probabilities and their time to converge to a stable state. Comparisons are made in a hexagonal macro-cellular system, and in two metropolitan micro-cellular systems. The Power Control with Removals Combined algorithm emerges as practically the best approach with respect to both criteria.
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| 10. |
- Andersin, Michael, et al.
(författare)
-
Soft Admission in Cellular PCS with Constrained Power Control and Noise
- 1995
-
Ingår i: Proc 5th WINLAB Workshop on Third Generation Wireless Information Networks. ; , s. 287-320
-
Konferensbidrag (refereegranskat)abstract
- We study the mobile admission control problem in a cellular PCS network where trans- mitter powers are constrained and controlled by a Distributed Constrained Power Control (DCPC) algorithm. Receivers are subject to non-negligible noise, and the DCPC attempts to bring each receiver's CIR (Carrier to Interference Ratio) above a given quality target. Two classes of distributed admission controls are considered. One is a Non-Interactive Admission Control (N-IAC), where an admission decision is instantaneously made based on the system state. The other is an Interactive Admission Control (IAC), under which the new mobile is permitted to interact with one or more potential channels before a decision is made. The algorithms are evaluated with respect to their execution time, and their decision errors. Two types of errors are examined. Type I error, where a new mobile is erroneously accepted and results an outage; and type II error, where a new mobile is erroneously rejected and results in blocking. The algorithms in the N-IAC class accept a new mobile, if and only if the uplink and the downlink interferences are below certain corresponding thresholds. These algorithms are subject to errors of type I and type II. In the IAC class, we derive a Soft and Safe (SAS) admission algorithm, which is type I and type II error free, and protects the CIRs of all active links at any moment of time. A Fast-SAS version which is only type I error free, is proposed for practical implementation, and evaluated in several case studies.
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| 11. |
- Andersin, Michael, et al.
(författare)
-
Soft and safe admission control in cellular networks
- 1997
-
Ingår i: IEEE/ACM Transactions on Networking. - : IEEE/ACM. - 1063-6692 .- 1558-2566. ; 5:2, s. 255-265
-
Tidskriftsartikel (refereegranskat)abstract
- We study the mobile admission control problem in a cellular PCS network where transmitter powers are constrained and controlled by a distributed constrained power control (DCPC) algorithm. Receivers are subject to nonnegligible noise, and the DCPC attempts to bring each receiver's CIR (carrier-to-interference ratio) above a given quality target. Two classes of distributed admission control are considered. One is a noninteractive admission control (N-IAC), where an admission decision is instantaneously made based on the system state. The other is an interactive admission control (IAC), under which the new mobile is permitted to interact with one or more potential channels before a decision is made. The algorithms are evaluated with respect to their execution time and their decision errors. Two types of errors are examined: type I error, where a new mobile is erroneously accepted and results in outage; and type II error, where a new mobile is erroneously rejected and results in blocking. The algorithms in the N-IAC class accept a new mobile if and only if the uplink and the downlink interferences are below certain corresponding thresholds. These algorithms are subject to errors of type I and type II. In the IAC class, we derive a soft and safe (SAS) admission algorithm, which is type I and type II error free, and protects the CIR's of all active links at any moment of time. A fast-SAS version, which is only type I error-free, is proposed for practical implementation, and is evaluated in several case studies.
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| 12. |
- Azari, Amin, 1988-
(författare)
-
Energy Efficient Machine-Type Communications over Cellular Networks : A Battery Lifetime-Aware Cellular Network Design Framework
- 2016
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Internet of Things (IoT) refers to the interconnection of uniquely identifiable smart devices which enables them to participate more actively in everyday life. Among large-scale applications, machine-type communications (MTC) supported by cellular networks will be one of the most important enablers for the success of IoT. The existing cellular infrastructure has been optimized for serving a small number of long-lived human-oriented communications (HoC) sessions, originated from smartphones whose batteries are charged in a daily basis. As a consequence, serving a massive number of non-rechargeable machine-type devices demanding a long battery lifetime is a big challenge for cellular networks.The present work is devoted to energy consumption modeling, battery lifetime analysis, and lifetime-aware network design for massive MTC services over cellular networks. At first, we present a realistic model for energy consumption of machine devices in cellular connectivity, which is employed subsequently in deriving the key performance indicator, i.e. network battery lifetime. Then, we develop an efficient mathematical foundation and algorithmic framework for lifetime-aware clustering design for serving a massive number of machine devices. Also, by extending the developed framework to non-clustered MTC, lifetime-aware uplink scheduling and power control solutions are derived. Finally, by investigating the delay, energy consumption, spectral efficiency, and battery lifetime tradeoffs in serving coexistence of HoC and MTC traffic, we explore the ways in which energy saving for the access network and quality of service for HoC traffic can be traded to prolong battery lifetime for machine devices.The numerical and simulation results show that the proposed solutions can provide substantial network lifetime improvement and network maintenance cost reduction in comparison with the existing approaches.
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| 13. |
- Azari, Amin, 1988-
(författare)
-
Serving IoT Communications over Cellular Networks : Challenges and Solutions in Radio Resource Management for Massive and Critical IoT Communications
- 2018
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Internet of Things (IoT) communications refer to the interconnections of smart devices, with reduced human intervention, which enable them to participate more actively in everyday life. It is expected that introduction of a scalable, energy efficient, and reliable IoT connectivity solution can bring enormous benefits to the society, especially in healthcare, wellbeing, and smart homes and industries. In the last two decades, there have been efforts in academia and industry to enable IoT connectivity over the legacy communications infrastructure. In recent years, it is becoming more and more clear that the characteristics and requirements of the IoT traffic are way different from the legacy traffic originating from existing communications services like voice and web surfing, and hence, IoT-specific communications systems and protocols have received profound attention. Until now, several revolutionary solutions, including cellular narrowband-IoT, SigFox, and LoRaWAN, have been proposed/implemented. As each of these solutions focuses on a subset of performance indicators at the cost of sacrificing the others, there is still lack of a dominant player in the market capable of delivering scalable, energy efficient, and reliable IoT connectivity. The present work is devoted to characterizing state-of-the-art technologies for enabling large-scale IoT connectivity, their limitations, and our contributions in performance assessment and enhancement for them. Especially, we focus on grant-free radio access and investigate its applications in supporting massive and critical IoT communications. The main contributions presented in this work include (a) developing an analytical framework for energy/latency/reliability assessment of IoT communications over grant-based and grant-free systems; (b) developing advanced RRM techniques for energy and spectrum efficient serving of massive and critical IoT communications, respectively; and (c) developing advanced data transmission/reception protocols for grant-free IoT networks. The performance evaluation results indicate that supporting IoT devices with stringent energy/delay constraints over limited radio resources calls for aggressive technologies breaking the barrier of the legacy interference-free orthogonal communications.
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| 14. |
- Badia, Leonardo, et al.
(författare)
-
An Economic Model For The Radio Resource Management In Multimedia Wireless Systems
- 2004
-
Ingår i: Computer Communications. - : Elsevier BV. - 0140-3664 .- 1873-703X. ; 27:11, s. 1056-1064
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we study the connection between radio resource management (RRM) and economic parameters, whose application in multimedia communication system is a challenging task. In fact, a real network provider has to consider other parameters, besides the common goals of RRM like throughput maximisation or meeting constraints connected with the quality of service. In particular, when the financial needs of the provider and the reaction of the users to prices are taken into account, economics have to be introduced in the analysis. We intend to study multimedia communication systems by including well-known economic models and reasonable considerations in the usual radio resource allocation scenario. To do this, we present a model of users' satisfaction, which considers the effects of both users' request and price paid. In this way, it is possible to investigate the relationship between the radio resource allocation and the provider revenue. Other conclusions can be derived as well, e.g. for the pricing strategy planning or the network dimensioning. Thus, we give analytical insight and numerical results, which highlight that the network management is heavily affected by the economic scenario.
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| 15. |
- Badia, Leonardo, et al.
(författare)
-
An Economic Model for the Radio Resource Management in Multimedia Wireless Systems
- 2003
-
Konferensbidrag (refereegranskat)abstract
- In this paper, we study the connection between Radio Resource Management and economic parameters, whose application in multimedia communication system is a challenging task. In fact, a real network provider has to consider other parameters, besides the common goals of Radio Resource Management like throughput maximisation or meeting constraints connected with the Quality of Service. In particular, when the financial needs of the provider and the reaction of the users to prices are taken into account, economics have to be introduced in the analysis. We intend to study multimedia communication systems by including well-known economic models and reasonable considerations in the usual Radio Resource Allocation scenario. To do this, we present a model of users'satisfaction, which considers the effects of both users' request and price paid. In this way it is possible to investigate the relationship between the Radio Resource Allocation and the provider revenue. Other conclusions can be derived as well, e.g., for the pricing strategy planning or the network dimensioning. Thus, we give analytical insight and numerical results which highlight that the network management is heavily affected by the economic scenario.
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| 16. |
- Badia, Leonardo, et al.
(författare)
-
Demand and Pricing Effects on the Radio Resource Allocation of Multimedia Communication Systems
- 2003
-
Ingår i: Conference Record / IEEE Global Telecommunications Conference. - : IEEE. ; , s. 4116-4121
-
Konferensbidrag (refereegranskat)abstract
- Over the years, Radio Resource Management has been benchmarked mostly by its technical merits. For a service provider, however, also economics must be reckoned with. When the financial needs of the provider and the satisfaction of the users are considered, common objectives in radio resource management like maximising throughput or meeting various quality constraints, may no longer be sufficient. We analyse next generation communication systems by including models of economics, presented in the literature, and reasonable considerations to depict the users/provider relationship in a generalised multimedia environment. In particular, we develop a model of users' satisfaction, in which both requested Quality of Service and price paid are taken into account. The model enables us to investigate how resource allocation dynamics affect operator revenues and to derive some useful insights. The Radio Resource Management can be shown to highly depend on economic considerations. The provider's task to determine the best usage of the network capacity is heavily affected by the users' service demand and their reactions to the pricing policy. Thus, the economic scenario needs to be taken into account to efficiently exploit the constrained radio resource.
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| 17. |
- Berg, Miguel, et al.
(författare)
-
A Radio Resource Management Concept for "Bunched" Personal Communication Systems
- 1997
-
Konferensbidrag (refereegranskat)abstract
- The radio resource management (RRM) techniques used in current 2nd generation mobile communication systems rely heavily on fixed frequency or timeslot allocation techniques which are not well suited for large variations in data rates. Spread spectrum systems proposed provide partial solutions to this problem but exhibit deficiencies when faced with uneven user populations. The overall objective of ACTS project AC090 FRAMES is to define, develop and evaluate a wideband multiple radio access scheme fulfilling the UMTS requirements. Within the project several RRM concepts have been proposed. The "bunch" concept discussed in this paper uses synchronous dynamic physical layer radio resource reservation combined with fast SIR based power control in a local cluster ("bunch"). Uncontrolled, "inter bunch", interference is handled by time/frequency hopping ("interference averaging"). In the paper some initial performance results are presented.
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| 18. |
- Berggren, Fredrik, et al.
(författare)
-
Dynamic Spectrum Access, Phase 1 Scenarios and research challenges
- 2004
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The currently used mechanisms for spectrum management are a contributing factor to the long lead times from innovation to market in wireless technologies andsystems. This has in turn been a major contributing factor to the dominance of the large telecom companies in the European and World markets, whereas very few innovative enterprises have exhibited consistent growth, although the technicalcompetence in Sweden is very high in this area. Alternative spectrum management regimes, such as the introduction of "unlicensed bands" have proven very effective in lowering entry thresholds for smaller companies (e.g the WLAN business). In addition, experts claim that the spectrum requirements for communication purposes will increase by as much as 200-300 % up to 2010. At the same time the actual usage of the electromagnetic spectrum is very inefficient.The project aims at studying new more, flexible, spectrum allocation regimeswhich, in combination with new technologies, such as multi-radio access, novelbroadband access techniques, software defined radio and spatial techniques (e.g.smart antennas, multi-hop schemes) have the potential of lowering the entry thresholds for new actors and provide radical improvement to the efficiency ofspectrum usage. Further the aim is to investigate the economic and regulatory consequences of such Dynamic Spectrum Access technologies and managementregimes. The results will provide input to future policies in spectrum management. The project has been divided into a first, pre-study phase and a second, research phase. The first phase was launched in Dec of 2004 and the second phase is planned to start in Jan 2005. The first phase of the project, reported here, has the aim toprovide a qualitative assessment of the potential benefits of dynamic spectrum access regimes. The analysis in the report and other studies in the area, indeed indicate there is a potential to both lower the entry thresholds for new actors as well as provide radical improvement to the efficiency of spectrum usage. The area isdefinitely of significant issues and the project should be continued studying the DSA concepts in more detail.Further, using a systematic procedure, a number of critical areas and bottleneck problems were identified. Our conclusion is that more research is needed in theseareas to achieve the above mentioned benefits. As `side effect' in this procedure, a number of novel and interesting spectrum management concepts were derived, e.g.the `real-time spectrum trading' and `use rights' concepts. Out of this gross list ofinterest problems, a number of highly important problems were selected, matching the competence of the project team. These problems are proposed to be the focus ofthe next phase in the project.Finally, the report provides an overview of the most important ongoing research and policy-making activities in the DSA-area.
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| 19. |
- Berggren, F., et al.
(författare)
-
Joint power control and intracell scheduling of DS-CDMA nonreal time data
- 2001
-
Ingår i: IEEE Journal on Selected Areas in Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8716 .- 1558-0008. ; 19:10, s. 1860-1870
-
Tidskriftsartikel (refereegranskat)abstract
- The performance of DS-CDMA systems depends on the success in managing interference arising from both intercell and intracell transmissions. Interference management in terms of power control for real time data services like voice has been widely studied and shown to be a crucial component for the functionality of such systems. In this work we consider the problem of supporting downlink nonreal time data services, where in addition to power control, there is also the possibility of controlling the interference by means of transmission scheduling. One such decentralized schedule is to use time division so that users transmit in a one-by-one fashion within each cell. We show that this has merits in terms of saving energy and increasing system capacity. We combine this form of intracell scheduling with a suggested distributed power control algorithm for the intercell interference management. We address its rate of convergence and show that the algorithm converges to a power allocation that supports the nonreal time data users, using the minimum required power while meeting requirements on average data rate. Numerical results indicate a big potential of increased capacity and that a significant amount of energy can be saved with the proposed transmission scheme.
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| 20. |
- Berggren, F., et al.
(författare)
-
Throughput and energy consumption tradeoffs in pathgain-based constrained power control in ALOHA networks
- 2000
-
Ingår i: IEEE Communications Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1089-7798 .- 1558-2558. ; 4:9, s. 283-285
-
Tidskriftsartikel (refereegranskat)abstract
- Power control has been proposed as a tool to improve the performance of packet radio systems in terms of increased throughput and battery lifetime for mobile terminals. In this paper we study the tradeoff between transmitter dynamic range, average energy consumption and the achievable throughput for a simple pathgain based power control algorithm in a slotted ALOHA radio system. The results show that increasing the throughput significantly by means of transmitter power control requires only a very moderate increase in energy consumption and transmitter dynamic range.
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| 21. |
- Bria, Aurelian, et al.
(författare)
-
4th Generation Wireless Infrastructures : Scenarios and Research Challenges
- 2001
-
Ingår i: IEEE personal communications. - : IEEE. - 1070-9916 .- 1558-0652. ; 8:6, s. 25-31
-
Tidskriftsartikel (refereegranskat)abstract
- A "fourth generation" of wireless systems, likely to appear after the successful deployment of the current third-generation systems, is frequently debated these days. This article presents some of the results of the Fourth Generation Wireless project (4GW) of the Personal Computing and Communications program (PCC), the major Swedish academic research effort on future communications systems, launched in late 1997. In the 4GW project, scenarios have been used as tools for formulating relevant research topics related to future wireless systems. By working with scenarios the project group has been able to challenge some of the assumptions commonly made in the field of wireless research. Since the project group is multidisciplinary, the work has also helped the members of the project group to understand the differences between the research traditions to which they belong. The scenarios, as well as the ensuing research into various wireless related topics, point to a vision of fourth-generation systems where "low-hierarchy" user-deployed infrastructures are the prime candidate. Fourth-generation systems will offer short- to moderate-range communications with very high data rates (>100 Mb/s). They are likely to employ array signal processing and ad hoc operation to provide the required coverage. A key aspect of their design will be the fact that they will be deployed in environments where large-scale wireless, and wired, infrastructures are already in operation.
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| 22. |
- Bria, Aurelian, 1975-
(författare)
-
Mobile Multimedia Multicasting in Future Wireless Systems : A Hybrid Cellular-Broadcasting System Approach
- 2008
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This dissertation addresses the problem of providing a®ordable mobile mul-timedia services in wide area wireless networks. The approach is to con-sider novel system architectures, based on reusing and sharing of the ex-isting network infrastructure for cellular and terrestrial TV broadcastingsystems. The focus has been on the radio resource management techniques,and the evaluation of the potential cost savings, compared to traditionalevolution tracks of the cellular and broadcasting systems.The studies show that deployment cost of a wide area broadcastingnetwork, using DVB-H technology, is very large if high data rate and fullarea coverage is targeted. For this reason we propose to avoid the broad-casting infrastructure dimensioning for full area coverage, and use insteadthe cellular systems to enable error correction for broadcasting transmis-sions. For the special case of mobile users, the chosen approach is to tradesystem's cost and capacity for improved perceived coverage. This trade-o®is enabled by the use of application layer forward error correction, usingRaptor coding.The general purpose Ambient Networks technology was chosen to en-able a platform for inter-operability between cellular and broadcasting sys-tems, especially the necessary interfaces. Under the Ambient Networksframework, we investigate the achievable cost savings o®ered by a hybridcellular-broadcasting system when combinations of broadcast and point-to-point transmissions are jointly utilized to provide ¯le transfers and stream-ing services. Two cases were investigated: one where the cellular systemacts as a replacement and deliver the data in the areas where broadcastingtransmissions cannot reach, and another one where cellular system carriesparity data to users that experience temporary outage in the broadcastingsystem. The results are encouraging, as they show that ¯le transfer costcan be reduced by more than 50%, but only under certain conditions.On a short term, hybrid cellular-broadcasting systems based on 3G andDVB-H, o®er a good platform for testing new and innovative mobile TVservices, enriched with interactivity and content personalization. From atechnical perspective, the outcomes of the presented studies indicate thatfuture systems built on hybrid cellular-broadcasting infrastructures are ableprovide a long term and cost e±cient solution for delivery of a®ordablebroadband multimedia services to mobile users. However, today's cellularand broadcasting systems live in di®erent worlds, are driven by di®erentrevenue models, and they are now starting to compete, instead of cooperate,for controlling the multimedia delivery channels to mobile users.
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| 23. |
- Bria, Aurelian, et al.
(författare)
-
Overall design of 4th Generation Wireless Infrastructures (4GW)
- 2002
-
Konferensbidrag (refereegranskat)abstract
- An important factor contributing to this uncertainty is that we have very limited knowledge about the future environment in which a fourth generation wireless infrastructure should function. Which of today's systems will still exist when a potential 4G infrastructure is deployed? Which systems and solutions will be considered successful then? What technical bottlenecks will be apparent ten years from now? What market impact will third generation wireless systems have? How will this affect user behavior, and user demands? How much money do prospective users have available to pay for services provided over this infrastructure? This paper presents some of the conclusion of of the Fourth Generation Wireless Infrastructure project (4GW) of the Personal Computing and Communications program (PCC), the major Swedish academic research effort on future communications systems launched in late 1997(1). The vision of the PCC project has been "Personal Multimedia to everyone at today's prices for fixed telephony". In 4GW a scenario-based approach has been used to tackle the issue of identifying reasonable research topics. In the paper we will present this method, and demonstrate how it interfaces with traditional research methods in the fields that the 4GW project incorporates. We will also give an overview of some research results from the project. Finally, we will conclude these results as a vision of what fourth generation wireless infrastructures might become
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| 24. |
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| 25. |
- Casimiro Ericsson, Nilo, 1970-
(författare)
-
Revenue Maximization in Resource Allocation : Applications in Wireless Communication Networks
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Revenue maximization for network operators is considered as a criterion for resource allocation in wireless cellular networks. A business model encompassing service level agreements between network operators and service providers is presented. Admission control, through price model aware admission policing and service level control, is critical for the provisioning of useful services over a general purpose wireless network. A technical solution consisting of a fast resource scheduler taking into account service requirements and wireless channel properties, a service level controller that provides the scheduler with a reasonable load, and an admission policy to uphold the service level agreements and maximize revenue, is presented.Two different types of service level controllers are presented and implemented. One is based on a scalar PID controller, that adjusts the admitted data rates for all active clients. The other one is obtained with linear programming methods, that optimally assign data rates to clients, given their channel qualities and price models.Two new scheduling criteria, and algorithms based on them, are presented and evaluated in a simulated wireless environment. One is based on a quadratic criterion, and is implemented through approximative algorithms, encompassing a search based algorithm and two different linearizations of the criterion. The second one is based on statistical measures of the service rates and channel states, and is implemented as an approximation of the joint probability of achieving the delay limits while utilizing the available resources efficiently.Two scheduling algorithms, one based on each criterion, are tested in combination with each of the service level controllers, and evaluated in terms of throughput, delay, and computational complexity, using a target test system. Results show that both schedulers can, when feasible, meet explicit throughput and delay requirements, while at the same time allowing the service level controller to maximize revenue by allocating the surplus resources to less demanding services.
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