| 1. |
- Al-Dulaimi, Anwer, et al.
(författare)
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5G Green Communications : C-RAN Provisioning of CoMP and Femtocells for Power Management
- 2016
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Ingår i: 2015 IEEE International Conference on Ubiquitous Wireless Broadband (ICUWB). - Piscataway, NJ : IEEE Communications Society. - 9781467365550
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Konferensbidrag (refereegranskat)abstract
- The fifth generation (5G) wireless network is expected to have dense deployments of cells in order to provide efficient Internet and cellular connections. The cloud radio access network (C-RAN) emerges as one of the 5G solutions to steer the network architecture and control resources beyond the legacy radio access technologies. The C-RAN decouples the traffic management operations from the radio access technologies leading to a new combination of virtualized network core and fronthaul architecture. In this paper, we first investigate the power consumption impact due to the aggressive deployments of low-power neighborhood femtocell networks (NFNs) under the umbrella of a coordinated multipoint (CoMP) macrocell. We show that power savings obtained from employing low power NFN start to decline as the density of deployed femtocells exceed certain threshold. The analysis considers two CoMP sites at the cell-edge and intra-cell areas. Second, to restore the power efficiency and network stabilization, a C-RAN model is proposed to restructure the NFN into clusters to ease the energy burden in the evolving 5G systems. Tailoring this to traffic load, selected clusters will be switched off to save power when they operate with low traffic loads
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| 2. |
- Celik, Haris
(författare)
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Feasibility and Performance of Dynamic TDD in Dense and Ultra-Dense Wireless Access Networks
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Meeting the seemingly never-ending increase in traffic over wireless networks presents a major challenge for future mobile network design. Given that much of the traffic is expected to be more time-varying and unpredictable, time division duplexing (TDD) is gaining increasing favorability in part thanks to its ability to better accommodate network-wide traffic variations. In order to account for traffic variations in individual cells on much shorter time scales, a more flexible variant called dynamic TDD has resurfaced as a promising technique to further improve resource utilization and performance. In dynamic TDD the traffic in each cell can be served immediately in either direction, but generates same-entity interference which is potentially more harmful. To avoid the much stronger downlink from saturating the uplink, this thesis considers dynamic TDD for dense and ultra-dense networks where transmission powers in the two directions are of comparable strength. Still, inter-cell interference remains an issue given the close proximity of some links. Because of the large number of cells comprising dense and ultra-dense networks, it is imperative that the interference management be both effective and scalable, which is the main focus of this thesis.In the first part we focus on scalable radio resource management (RRM). We show that non-cooperative dynamic TDD is feasible for indoor ultra-dense deployment and highlight the benefit of employing beamsteering at both the base station (BS) and user equipment (UE) to mitigate interference distributively, especially at high load. Recognizing that beamsteering is better suited for higher frequencies and high data rate applications, we proceed to investigate the efficacy of receive-side interference management in the form of successive interference cancellation (SIC). Being that the interference distribution is different in dynamic TDD, we show that it suffices to cancel only strongest interferer at the UE side and the two strongest interferers at the BS. The combined benefit of SIC and dynamic TDD in reducing delay for low-rate traffic is also displayed. Next, we introduce limited inter-cell information exchange in order to leverage the resource allocation in the medium access control (MAC). To minimize the amount of information exchange and preserve scalability, a scheduling framework is proposed that relates real-time traffic to inter-BS interferences measured offline and mapped to the individual activation probability of each BS. The proposed scheme is shown to perform well with respect to comparable scalable schedulers when interference is high, and optimally when interference is low.In ultra-dense networks it is expected that some BSs might not have a UE to serve. In the second part, we therefore introduce cooperation to utilize the otherwise idle BSs to improve network performance. To mitigate both same- and other-entity interference, zero forcing (ZF) precoding is employed where not only downlink UEs but also uplink BSs are included in the beamforming. Results show that both uplink and downlink performance improves at low and medium load, and that it is possible to trade performance in the two directions at high load.
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| 3. |
- Osseiran, Afif, et al.
(författare)
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CELTIC CP5-026 WINNER+, D2.1 Preliminary WINNER+ System Concept
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This deliverable provides an overview of the WINNER+ system concept which encompasses the following innovations areas for IMT-Advanced technologies: advanced RRM, spectrum technologies, advanced co-located antennas and coordinated multipoint systems. The concepts of each of these areas are described thoroughly. These concepts are composed of techniques and methods that were identified out of a wider set.
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| 4. |
- Osseiran, Afif, et al.
(författare)
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CELTIC CP5-026 WINNER+, D2.2 Enabling Techniques for LTE-A and beyond
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This deliverable summarizes the most promising enabling techniques for LTE-A and beyond in seven major areas. These areas are: Carrier Aggregation, Coordinated Multipoint Systems, Femtocells, Network Coding, MIMO, Quality of Service, Resource allocation, and Relaying. A description of the most relevant scenarios where the techniques can be used is given. Further the end-2-end performance approach is presented. Finally future research directions of enabling techniques beyond LTE-A are given.
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| 5. |
- Svensson, Tommy, 1970, et al.
(författare)
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CELTIC CP5-026 WINNER+, D1.9 Final Innovation Report
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This deliverable is the final innovation report from the innovation workpackage in WINNER+. The document describes the latest innovations and their assessment as well as summarizes the innovations developed in the work package during the project. We analyze the suitability of these innovations as technology enablers for improving current systems, in particular IMT Advanced and beyond.
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| 6. |
- Wang, Chihyu, et al.
(författare)
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Game-theoretic approaches in heterogeneous networks
- 2015
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Ingår i: Game Theory Framework Applied to Wireless Communication Networks. - Hershey, PA : IGI Global. - 9781466686434 ; , s. 88-102
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Bokkapitel (refereegranskat)abstract
- Improving capacity and coverage is one of the main issues in next-generation wireless communication. Heterogeneous networks (HetNets), which is currently investigated in LTE-Advanced standard, is a promising solution to enhance capacity and eliminate coverage holes in a cost-efficient manner. A HetNet is composed of existing macrocells and various types of small cells. By deploying small cells into the existing network, operators enhance the users' quality of service which are suffering from severe signal degradation at cell edges or coverage holes. Nevertheless, there are numerous challenges in integrating small cells into the existing cellular network due to the characteristics: unplanned deployment, intercell interference, economic potential, etc. Recently, game theory has been shown to be a powerful tool for investigating the challenges in HetNets. Several game-theoretic approaches have been proposed to model the distributed deployment and self-organization feature of HetNets. In this chapter, the authors first give an overview of the challenges in HetNets. Subsequently, the authors illustrate how game theory can be applied to solve issues related to HetNets.
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| 7. |
- Wang, Chih-Yu, et al.
(författare)
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Game-Theoretic Approaches In Heterogeneous Networks
- 2018
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Ingår i: Game Theory: Breakthroughs in Research and Practice. - Hershey, PA : IGI Global. - 9781522525943 - 1522525947 - 9781522525950 ; , s. 204-218
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Bokkapitel (refereegranskat)abstract
- Improving capacity and coverage is one of the main issues in next-generation wireless communication. Heterogeneous networks (HetNets), which is currently investigated in LTE-Advanced standard, is a promising solution to enhance capacity and eliminate coverage holes in a cost-efficient manner. A HetNet is composed of existing macrocells and various types of small cells. By deploying small cells into the existing network, operators enhance the users' quality of service which are suffering from severe signal degradation at cell edges or coverage holes. Nevertheless, there are numerous challenges in integrating small cells into the existing cellular network due to the characteristics: unplanned deployment, intercell interference, economic potential, etc. Recently, game theory has been shown to be a powerful tool for investigating the challenges in HetNets. Several game-theoretic approaches have been proposed to model the distributed deployment and self-organization feature of HetNets. In this chapter, the authors first give an overview of the challenges in HetNets. Subsequently, the authors illustrate how game theory can be applied to solve issues related to HetNets.
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| 8. |
- Yang, Guang
(författare)
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Throughput and Latency of Millimeter-Wave Networks : Performance Analyses and Design Principles
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Nowadays, the ever-increasing demands on higher data rates and better serviceperformance have posed extremely huge challenges to the existing wireless communicationswithin sub-6 GHz bands, mainly due to the spectrum scarcity in lowerfrequency bands. In recent years, the millimeter-wave (mm-wave) technology, as apromising candidate to meet the aforementioned demands, have attracted extensiveresearch attention, and has been regarded as one of the key enablers for theforthcoming the 5th generation (5G) mobile communications. The main featuresof mm-wave communications include: abundant spectral resources, high penetrationloss, severe path loss, weak multi-path effects, and narrow antenna beams, andthese particular features make the potential challenges and solutions with mm-wavediffer a lot from those in the conventional 6-GHz systems.It is known that the high throughput and the low latency are two critical qualityof-service (QoS) aspects in future mobile networks, while the related research withmm-wave are fairly recent and insufficient in the past few years. Motived by theurgent needs for further development and the blanks remained in previous works,in this doctoral thesis, we investigate the throughput and the latency in mm-wavenetworks through conducting performance analyses and identifying design principles,with the objective of seeking clues for improving the QoS of mm-wave wirelesscommunications in practice.Our main research regarding throughput and latency in mm-wave networksthat are included in this doctoral thesis can be categorized from the following threeaspects:(i) Throughput of mm-wave relay networks: For indoor scenarios, we study thehalf-duplex (HD) relaying with mm-wave in the presence of random linkblockages, where a distance-based routing algorithm is proposed to maximizethe throughput. For outdoor scenarios, focusing on a two-hop amplifyand-forward (AF) relay network in the HD or the full-duplex (FD) mode, weinvestigate the impacts of beamwidth, ground reflections, and self-interferencecoefficient on the throughput, where Gaussian-type directional antenna modeland two-ray channel model are jointly adopted.(ii) Latency analysis via stochastic network calculus: With the aid of stochasticnetwork calculus, we derive upper bounds for the probabilistic delay tokeep track of the latency performance of buffer-aided mm-wave networks. We mainly study mm-wave systems designed in tandem or parallel manners,and also consider a hybrid design that combines the tandem and parallelschemes in a flexible manner. Moreover, the capability of achieving low-latencymm-wave communications is characterized and investigated in terms of effectivecapacity, and the comparison among different transmission schemes isconducted to identify the respective strengths and proper conditions for theirapplications.(iii) Traffic allocation for low-latency mm-wave systems: Traffic allocation schemesfor low latency in buffer-aided mm-wave networks are investigated. Due tothe use of buffers, the delay optimization problem hereby differs from thosewithout buffers, where the conventional graph-based network optimizationtechniques become intractable. We demonstrate the impacts of different trafficallocation schemes on the latency. For multi-hop networks with multipleparallel channels in each hop, we consider both local and global traffic allocationschemes, quantify their resulting end-to-end (E2E) latencies, and analyzethe respective strengths and weaknesses.
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