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  • 151. Hossain, M. M. Aftab
    et al.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Bjornson, Emil
    Jantti, Riku
    Energy-Efficient Load-Adaptive Massive MIMO2015In: 2015 IEEE GLOBECOM WORKSHOPS (GC WKSHPS), 2015Conference paper (Refereed)
    Abstract [en]

    Massive MIMO is a promising technique to meet the exponential growth of global mobile data traffic demand. However, contrary to the current systems, energy consumption of next generation networks is required to be load adaptive as the network load varies significantly throughout the day. In this paper, we propose a load adaptive massive MIMO system that varies the number of antennas following the daily load profile (DLP) in order to maximize the downlink energy efficiency (EE). A multi- cell system is considered where each base station (BS) is equipped with a large number of antennas to serve many single antenna users. In order to incorporate DLP, each BS is modeled as an M/G/m/m state dependent queue under the assumption that the network is dimensioned to serve a maximum number of users at the peak load. For a given number of users in a cell, the optimum number of active antennas maximizing EE is derived. The EE maximization problem is formulated in a game theoretic framework where the number of antennas to be used by a BS is determined through best response iteration. This load adaptive system achieves overall 19% higher EE compared to a baseline system where the BSs always run with the fixed number of antennas that is most energy efficient at peak load and that can be switched-off when there is no traffic.

  • 152.
    Hossain, M. M. Aftab
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Jantti, Riku
    Aalto Univ, Sch Elect Engn, Espoo, Finland..
    Dynamic capacity sharing based energy saving market for MNOs2017In: Globecom 2017 - 2017 IEEE Global Communications Conference, Institute of Electrical and Electronics Engineers (IEEE), 2017Conference paper (Refereed)
    Abstract [en]

    As the larger share of total energy consumed by mobile network operators (MNOs) is wasted in order to ensure coverage, three to five MNOs covering the same geographical area results in enormous energy waste. In order to cater for the data tsunami with almost zero marginal revenue, required densification of cells are not sustainable from both Capex and Opex perspective. Even with densification of networks, it is hard to satisfy the performance requirement of the cell edge users due to interference. However, the performance can be upgraded as well as energy can be saved by the offloading of the cell edge users to other MNOs if regulator and MNOs resort to appropriate mechanism. In our previous work, we proposed a double auction based energy saving market mechanism where MNOs participate in bidding to share coverage and capacity in order to save energy, especially during low to medium load. Unlike previous work, in this paper we use this mechanism that involve cell level bidding, i.e., cells bid for each user which not only allows total offloading of the cells at the low load but also offloading of cell edge users among the MNOs during high load. As a result, the energy saving potential becomes very high also at high load conditions along with improvement in performance of cell edge users.

  • 153.
    Hossain, M. M. Aftab
    et al.
    AALTO.
    Jantti, Riku
    AALTO.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Dimensioning of PA for massive MIMO system with load adaptive number of antennas2014In: Globecom Workshops (GC Wkshps), 2014, 2014, p. 1102-1108Conference paper (Refereed)
    Abstract [en]

    This paper takes into consideration the non-ideal efficiency characteristics of realistic power amplifiers (PAs) along with the daily traffic profile in order to investigate the impact of power amplifier dimensioning on the energy efficiency of load adaptive massive MIMO system. A multicellular system has been considered where each base station (BS) is equipped with large number of antennas to serve many single antenna users. For a given number of users in a cell, the optimum number of active antennas maximizing energy efficiency (EE) has been derived where total BS downlink power is assumed to be fixed. Under the same assumption, the power amplifiers have been dimensioned in a way that maximize network energy efficiency not only for a for a single time snapshot but over twenty four hours of operation while considering dynamic efficiency characteristics of the PAs. In order to incorporate this daily load profile, each BS has been modeled as an M/G/c/c state dependent queue under the assumption that the network is dimensioned to serve a maximum number of users at a time corresponding to 100% cell traffic load. This load adaptive system along with the optimized PA dimensioning achieves 30% higher energy efficinecy compared to a base line system where the BSs always run with a fixed number of active antennas which are most energy efficient while serving 100% traffic load.

  • 154.
    Hu, Ning
    et al.
    Tsinghua University.
    Chen, Xiang
    Tsinghua University.
    Zhong, Xiaofeng
    Tsinghua University.
    Ben Slimane, Slimane
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Li, Yunzhou
    Tsinghua University.
    Wang, Jing
    Tsinghua University.
    Energy-Efficient Relaying Strategy with Network Coding in Two-Way Parallel Channels2011In: ISRN Communications and Networking, ISSN 2090-4355, Vol. 2011Article in journal (Refereed)
    Abstract [en]

    We consider a two-way communication assisted by parallel regenerative decode-and-forward relays operating in orthogonal channels. In a system with limited channel state information at each source and relay node, an optimum distributed power allocation strategy is proposed to minimize the total transmit power, providing a target signal-to-noise ratio at each destination with a target outage probability. Moreover, combined with opportunistic relaying and network coding, a distributed decision mechanism is proposed for the relay node to decide whether to help the transmission or not. In this proposal, each source works out the transmit power and the decision threshold then broadcasts them. The selected relay compares the decision threshold with the channel gain of its weaker relay-to-destination link, then determines whether to forward the networkcoded data or not. Simulation results show the advantage of this strategy in terms of energy efficiency for a two-hop two-way communication scenario. The proposed strategy is very flexible as it can trade outage to power consumption and vice versa.

  • 155.
    Hultell, Johan
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Berg, Miguel
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Generalized Roaming and Access Selection in Multi-Operator Environments2005Conference paper (Refereed)
    Abstract [en]

    In a multi-operator environment where several operators offer high-speed local wireless access, geographical sharing is an attractive way to increase the coverage and resource effificiency so that 'interesting' services can be offered. This paper investigates two different access selection strategies for three typical environments (hotspot, urban, and suburban) to establish when, and to what extent, the performance can be improved. In the first strategy users simply connect to the strongest access point (AP) whereas the users within the second strategy connect to the AP maximizing the instantaneous aggregated capacity according a greedy algorithm. Both strategies are compared to a reference case where users connect to the strongest AP belonging to their home operator.  We investigated a two-operator scenario with APs using CSMA/CA and the results indicate that a significant improvement, both in terms of coverage and resource efficiency, can be achieved if users simply connect to the strongest AP. Moreover the results show that further improvement is possible, especially in urban and hotspot environments, with more complex strategies.

  • 156.
    Hultell, Johan
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Ileri, Ömer
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture, Communication Systems, CoS.
    Selfish users in energy constrained ALOHA systems with power capture2011In: Wireless networks, ISSN 1022-0038, E-ISSN 1572-8196, Vol. 17, no 1, p. 199-212Article in journal (Refereed)
    Abstract [en]

    We consider a slotted ALOHA setting where backlogged, energy-constrained users selfishly select the probability with which they transmit packets. Packets are successfully received, even in case of collision, if the signal to interference plus noise ratio at the access point exceeds some threshold (power capture). The user problem of finding appropriate transmission probabilities is formulated as a static non-cooperative game and the performance limits for stationary and mobile scenarios are determined. The equilibrium analyses show that for stationary scenarios, users with high pathgains share the channel fairly while others never transmit. In the mobile case users utilize a binary strategy where they try to monopolize the channel when their pathgain exceeds some threshold that depends on system parameters (number of users, transmission costs, etc.). Otherwise they shut their transmitters off. Compared to traditional nondiscriminatory distributed multiaccess protocols the operating points achieved by selfish users generally increase sum-utility although this comes at the expense of larger user performance variations.

  • 157.
    Hultell, Johan
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Johansson, Klas
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    An Estimation of the Achievable User Throughput with National Roaming.Manuscript (preprint) (Other academic)
    Abstract [en]

    National roaming, that is allowing users to access networks of multiple domestic operator's, was discussed already during development of first and second generation mobile systems.For mobile voice services, however, the operators afforded to build networks with (almost) full coverage alone. The benefits with national roaming, in terms of increased coverage, trunking efficiency and lowered risk exposure, did consequently not exceedthe drawbacks associated with increased operator cooperation.Motivated by the considerable investments for providing coverage for mobile data services, and enabled by the commonradio resource management proposed for systems “Beyond 3G”,this paper1 evaluates the benefits with national roaming for besteffort data services. The results show that national roaming more than doubles the data rates for users at the cell border. Thisg ain is motivated by reduced path loss and lowered interference levels. Around half of the potential gain is captured already with nearly co-sited base stations, which suggests that the benefits for operators to coordinate their base station site plans are limited.

  • 158.
    Hultell, Johan
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Johansson, Klas
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Performance analysis of non-cosited evolved 2G and 3G multi-access systems2006In: IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, Helsinki, 2006Conference paper (Refereed)
    Abstract [en]

    An efficient combination of radio access technologies, integrated in a multi-access network, will be a key enabler in future provisioning of mobile data services. This paper addresses a scenario where an incumbent mobile network operator, with an existing 2G and 3G infrastructure, has deployed a dense WCDMA/HSPA macro-cell network in an urban area. With this high capacity network deployed, upgrading previous 2G and 3G systems with EDGE and HSPA respectively may seem obsolete. However, even though these systems may not support the intended data rates alone, they could, thanks to favorable propagation characteristics and the additional spectrum available, be useful as complements. Simulation results indicate that upgrading GPRS base stations with EDGE, or a sparse WCDMA macro cell layer with HSPA, mainly would benefit uplink transmission. For this case, the data rate that can be guaranteed with 95 % area availability (coverage) can be increased with approximately 40-100 %. In the downlink, though, the dense WCDMA/HSPA system alone supports user data rates of 500 kpbs for all relevant user densities. Thus, upgrading legacy infrastructure would be obsolete.

  • 159.
    Hultell, Johan
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Lungaro, Pietro
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Service Provisioning with Ad-hoc Deployed High-Speed Access Points in Urban Environments2005Conference paper (Refereed)
  • 160.
    Hultell, Johan
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Lungaro, Pietro
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Service Provisioning with Ad-Hoc Deployed High-Speed Access Points in Urban environments2005In: 2005 IEEE 16th International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC 2005, IEEE conference proceedings, 2005, Vol. 3, p. 2019-2023Conference paper (Refereed)
    Abstract [en]

     Exploiting user-deployed networks as part of a public infrastructure has been proposed as a concept to radically lower the cost of provisioning access and services in urban environments. An important question is how dense a network with spotty coverage has to be in order to support interesting services. In this paper1, we introduce a framework for evaluating the user-perceived performance for two service types, a time-critical news subscription service (involving streaming) and a more delay tolerant entertainment service ("web browsing"). The user terminals contain a memory cache and an "agent" that opportunistically downloads and stores relevant pieces of information as users walk close to the access points. Results show that above a critical access point density, that is still significantly lower than the one required for continuous coverage, the services start performing very well with little or no outdated information. In most studied scenarios, we are communication limited meaning that memory capacity is not a problem, but energy is.

  • 161.
    Hultell, Johan
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Markendahl, Jan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Competition and Cooperation in Wireless Multi-Access Networks2007In: Cognitive Wireless Networks: Concepts, Methodologies and Visions Inspiring the Age of Enlightenment of Wireless Communications / [ed] Frank H. P. Fitzek and Marcos D. Katz, Springer , 2007, 1, p. 109-132Chapter in book (Refereed)
  • 162.
    Hwang, Youngju
    et al.
    Yonsei University.
    Kim, Seong-Lyun
    Yonsei University.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Scenario making for assessment of secondary spectrum access2012In: IEEE wireless communications, ISSN 1536-1284, E-ISSN 1558-0687, Vol. 19, no 4, p. 25-31Article in journal (Refereed)
    Abstract [en]

    Secondary spectrum access, through which secondary users opportunistically access the underutilized radio spectrum, has emerged as a solution to cope with the perceived spectrum scarcity. The potential of secondary spectrum has therefore attracted industry players and regulators worldwide. To assess the real-life benefits of the secondary spectrum, it is crucial to estimate the amount of spectrum available for secondary use. This estimation requires a well defined set of models and parameters, which are collectively termed a scenario. In this article, we demonstrate the importance of scenario making in the quantitative assessment of secondary spectrum access. We first describe the elements that constitute a comprehensive secondary access scenario: a primary system and spectrum, a secondary system and usage, and the methods and context of spectrum sharing. Then we demonstrate how the assessment results of the spectrum availability differ depending on the scenario elements. We also illustrate the crucial aspects of a scenario in the business analysis, which, together with the technical assessment, is the input for the regulatory decision.

  • 163.
    Hwang, YoungJu
    et al.
    Yonsei University.
    Park, JiHong
    Yonsei University.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Kim, Seong-Lyun
    Yonsei University.
    On the throughput gain of device-to-device communications2015In: ICT Express, ISSN 2405-9595, Vol. 1, no 2, p. 67-70Article in journal (Refereed)
    Abstract [en]

    In an uplink underlaid device-to-device (D2D) cellular network, this paper considers its two aspects of throughput improvement. The two-fold gain comprises the throughput increase by offloading downlink cellular traffic to D2D communications, duplexing gain, and the increase by reusing uplink resources of D2D transmissions, capacity gain. Both impacts are investigated by exploiting stochastic geometry. On the basis of the analysis, a throughput optimal D2D operation guideline is provided for different network congestion environments.

  • 164.
    Händel, Peter
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Prasad, Sathyaveer
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Beckman, Claes
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Maximum likelihood estimation of reverberation chamber direct-to-scattered ratio2009In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 45, no 25, p. 1285-U24Article in journal (Refereed)
    Abstract [en]

    The exact maximum likelihood estimator of the direct-to-scattered ratio of the Rician channel in a reverberation chamber is derived and its performance analysed. It is shown that the estimator obeys a non-central F-distribution, the mean value and variance of which are derived. For well stirred chambers, it is shown that the systematic error in the estimated ratio may be significant.

  • 165.
    Ileri, Ömer
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture, Communication Systems, CoS.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture, Communication Systems, CoS.
    Broker Coordination in Demand Responsive Dynamic Spectrum Access Settings2009In: 2009 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS, VOLS 1-8, 2009, p. 2781-2786Conference paper (Refereed)
    Abstract [en]

    In this paper we propose cooperative/noncooperative operation models for revenue seeking spectrum brokers who coordinate to manage access to the same spectrum bands in adjacent areas. We consider a setting where users of spectrum are involved in peer-to-peer links with QoS requirements. Each wireless transmission (link) is priced collectively by all revenue seeking brokers whose responsibility areas are affected by the transmission (via interference). We propose a two-level coordination mechanism. At the pricing-level, the brokers affected by a given link collectively determine prices. At the admission level, all brokers potentially affected by all transmissions collectively determine the set of link requests that are to be permitted. The links are modeled as price sensitive users who may or may not form connections, based on the total price asked. Experimental results show that cooperation significantly increases both the number of active links and broker revenues. Relative gains achieved by pricing level cooperation alone or admission level cooperation alone depend on price sensitivity parameters for the links as well as the total number of link formation requests.

  • 166.
    Jalalinia, Shabnam S.
    et al.
    KTH, School of Information and Communication Technology (ICT).
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Green and resilient design of telecom networks with shared backup resources2017In: OPTICAL SWITCHING AND NETWORKING, ISSN 1573-4277, Vol. 23, p. 97-107Article in journal (Refereed)
    Abstract [en]

    Backbone telecommunication network infrastructures are deployed with redundant resources taking into account the backup capacity for protection in order to be resilient against link failures, and serving extremely large amount of data transmission resulting in increasing power consumption. In this study, the interplay between green and resilient network design, and flow routing mechanisms is analyzed. We propose Mixed Integer Linear Programming (MILP) models to obtain optimum solutions under various objectives: Minimizing consumption of (I) Capacity, (II) Capacity+ Power, and (III) Power. Two different shared backup protection (SBP) schemes (1) SBP-ind (failure independent) and (2) SBP-dep (failure dependent) are compared with dedicated path protection (DPP). It is assumed that network links utilized by only backup paths can be put into sleep mode. It is observed that when power consumption is minimized, the backup sharing decreases in SBP and, in the extreme case, it behaves similar to DPP. The models are generalized and valid for both IP traffic flow routing and lightpath routing. It is shown that for a sample network topology, to save e.g., 32.33% power, capacity consumption increases significantly, e.g., in SBP-ind up to 127.53%. In order to achieve a compromise between power and capacity consumption, we propose a multi-objective approach. All the MILP models are run and results are presented for a small scale European network topology as well as a larger scale sample US network topology. For larger problem instances ILP solutions are not scalable. Therefore, a novel energy efficient and survivable routing and network design algorithm, called energy-aware shared path protection (EASPP), addressing the trade-off caused by conflicting objectives of green and resilient network planning is proposed. Moreover this study presents a complete picture of various survivability mechanisms when power consumption is minimized together with the capacity consumption.

  • 167.
    Jansson, Carl-Gustaf
    et al.
    KTH, School of Information and Communication Technology (ICT), Computer and Systems Sciences, DSV. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Jonsson, Martin
    KTH, School of Information and Communication Technology (ICT), Computer and Systems Sciences, DSV. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Kanter, Theo G.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. Ericsson Research, Sweden.
    Kilander, Fredrik
    KTH, School of Information and Communication Technology (ICT), Computer and Systems Sciences, DSV. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Maguire Jr., Gerald Q.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Li, Wei
    KTH, School of Information and Communication Technology (ICT), Computer and Systems Sciences, DSV. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Context Middleware for Adaptive Services in Heterogeneous Wireless Networks: Concepts, Approach and Work-In-Progress in the ACAS Project2005In: VTC 2005-Spring: 2005 IEEE 61st Vehicular Technology Conference, Proceedings, IEEE , 2005, Vol. 5, p. 2954-2958Conference paper (Refereed)
    Abstract [en]

    This paper provides an overview of important results and work-in-progress within the ACAS project concerning context middleware to enable adaptive, user-centric, mobile services available to users via a heterogeneous wireless infrastructure.

  • 168. Jie, Xu
    et al.
    ShiChao, Li
    Ling, Qiu
    Slimane, Ben S.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    ChengWen, Yu
    Energy efficient downlink MIMO transmission with linear precoding2013In: Science China Information Sciences, ISSN 1674-733X, Vol. 56, no 2, p. 022309-Article in journal (Refereed)
    Abstract [en]

    Energy efficiency (EE) is becoming increasingly important for wireless cellular networks. This paper addresses EE optimization problems in downlink multiuser MIMO systems with linear precoding. Referring to different active transmit/receive antenna sets and transmission schemes as different modes, we propose a joint bandwidth/power optimization and mode switching scheme to maximize EE. With a specific mode, we prove that the optimal bandwidth and transmit power is either full transmit power or full bandwidth. After deriving the optimal bandwidth and transmit power, we further propose mode switching to select the mode with optimal EE. Since the optimal mode switching, i.e. exhaustive search, is too complex to implement, an alternative heuristic method is developed to decrease the complexity through reducing the search size and avoiding the EE calculation during each search. Through simulations, we demonstrate that the proposed methods can significantly improve EE and the performance is similar to the optimal exhaustive search.

  • 169.
    Jirattigalachote, Amornrat
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Skorin-Kapov, Nina
    Furdek, Marija
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Sparse power equalization placement for limiting jamming attack propagation in transparent optical networks2011In: Optical Switching and Networkning Journal, ISSN 1573-4277, E-ISSN 1872-9770, Vol. 8, no 4, p. 249-258Article in journal (Refereed)
    Abstract [en]

    The latest advances in Wavelength Division Multiplexing (WDM) technology are making it possible to build all-optical transparent WDM networks, which are expected to be able to satisfy the rapid growth of today's capacity demand. However, the transparency of such networks makes them highly vulnerable to deliberate attacks, specifically targeting the physical layer. Physical-layer attacks, such as high-power jamming, can cause severe service disruption or even service denial, enhanced by their capability to propagate through a transparent optical network. Several attack-aware routing and wavelength assignment algorithms have been proposed to reduce the possible disruption caused by high-power jamming attacks. However, even with network planning approaches which take network security, specifically physical-layer attacks, into account, resilience to deliberate attacks in such scenarios remains an issue. In this paper, we propose the use of wavelength-selective attenuators as power equalizers inside network nodes to limit the propagation of high-power jamming attacks. Due to the increased cost of optical switching nodes associated with the addition of power equalizers, we aim at minimizing their number through sparse power equalization placement. We developed a set of greedy algorithms to solve what we call the Power Equalization Placement (PEP) problem with the objective of minimizing the number of power equalizers needed to reduce, to a desired level, the propagation of high-power jamming attacks for a given routing scheme. We further improved upon these results by proposing a GRASP (Greedy Randomized Adaptive Search Procedure) heuristic with a somewhat longer execution time, but with significantly superior results. The performance evaluation results indicate that the proposed GRASP heuristic can achieve the same attack propagation reduction as can be obtained by equipping all nodes with power equalizers by placing them at less than 50% of the nodes on average, potentially yielding significant cost savings.

  • 170.
    Johansson, Klas
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    On the cost efficency of user deployed access points integrated in mobile networks.Manuscript (preprint) (Other academic)
    Abstract [en]

    Open access to private, user deployed, access points is a promising candidate for provisioning of high data rates in public wireless access systems. This deployment strategy should especially be an efficient method to serve indoor users in cities with a significant penetration of fixed broadband networks. We estimate the infrastructure cost for different mixes of operator deployed (HSDPAmacro cells and 802.11g WLAN) and user deployed access points. The network is dimensioned according to a stochastic(log-normally distributed) model for traffic density.Results indicate that, with the modelling and assumptions used, user deployed access points lower the infrastructure cost for traffic densities above 10Mbps/km2 (10 times thetraffic of typical private speech users in a city center).Moreover, only a few percent of the subscribers need to install open access points to cover a signifficant fraction of the total trafffc terminated indoors.

  • 171.
    Johansson, Klas
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture, Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Furuskär, Anders
    Ericsson Research, Sweden.
    Cost efficient capacity expansion strategies using multi-access networks2005In: VTC2005-SPRING: 2005 IEEE 61ST VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-5, PROCEEDINGS, IEEE , 2005, p. 2889-2993Conference paper (Refereed)
    Abstract [en]

    Multi-access networks and hierarchical cell structures are two common capacity expansion strategies for mobilenetwork operators. In both cases costs can be minimized fora set of available radio access technologies, given heterogeneous requirements on area coverage, capacity and quality of service. In this paper we quantify the infrastructure cost for a multi-accessnetwork composed of macro cellular HSDPA base stations and IEEE 802.11g WLAN access points. The network is dimensioned for an urban environment using a stochastic model for heterogeneous traffic density.With the used assumptions and modelling it is shown that a combination of HSDPA base stations deployed with 400mcell radius together with WLAN in hot spots are suffcient foraver age traffic densities up to around 50Mbps/km2 (50 timesthe traffic of typical private voice users today). In order to evaluate the sensitivity to different design features, we introducethe elasticity of infrastructure cost and can thereby show that it is more important to improve capacity in HSDPA than coverageper 802.11g access point. However, with a sparse deployment of HSDPA macro cells (800m radius) infrastructure cost ismore elastic to 802.11g coverage. The paper also indicatessome possibilities to differentiate future radio access technologies towards current systems.

  • 172.
    Johnsson, Martin
    et al.
    Ericsson Research.
    Markendahl, Jan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Ambient networking and related business concepts as support for regulatory initiatives and competition2006In: 5th Conference on Telecommunication Techno-Economics (CTTE 2006), 2006Conference paper (Refereed)
    Abstract [en]

    It is envisaged that future internetworkingtechnologies, such as those proposed within the AmbientNetworks (AN) project, would continue to further the openness ofinterfaces, and would open up new business opportunities for newplayers on the global market. This paper investigates andanalyses in what way regulatory support is needed to supportnew business models and value chains. It also checks whethercurrent trends in regulations support deployment of ambientnetworking concepts. Our view is that Ambient Networksconcepts like network composition, dynamic roaming andnew interfaces will enable the de-coupling of business rolesof the traditionally vertically integrated value chain. Thiscontributes to increased competition since any user will beable to use any service using “any” provider or network.

  • 173.
    Kang, Du Ho
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Cost Effective Interference Management in Ultra-dense Hotspot Mobile Broadband Systems2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Rapid mobile data traffic growth is becoming in a reality and several forecasts expect that it will be continued in upcoming years. It is expected that significant indoor investment will be made not only by traditional operators but also by facility owners for their own purposes. A key challenge to such local network providers is provisioning ever-increasing mobile traffic demand at the current level of production cost per bit. A popular deployment strategy so far is deploying WLAN networks. While denser indoor deployment is foreseen, the interference from inside of a network as well as other neighboring operators can be a limiting factor for higher capacity. Tighter interference management will certainly provide higher efficiency in network and spectrum usage. Nevertheless, costs to allow fast information sharing among access points are necessary for advanced interference coordination. Moreover, managing interference across networks owned by different operators raises not only infrastructure cost but also the network interrelatedness which operators are typically reluctant for business independency. When taking into account the cost and barriers for interference coordination, it is still not so obvious that coordination in wireless broadband systems will be advantageous to operators.

    In this thesis, we address the operator benefit of downlink interference coordination in two aspects: 1) multi-cell coordination with no interference from neighboring operators, and 2) inter-operator coordination in shared spectrum. In order to deal with interference and cost tradeoff analysis, we explicitly develop a techno-economic analysis framework and reform a traditional cost model. Numerical results indicate that the economic benefit of the multi-cell coordination significantly depends on propagation conditions and average user demand level. A self-deployed WLAN network can be the cheapest deployment option in closed areas up to certain average demand level. Over the demand level or in open areas, advanced joint processing schemes in a cellular domain may be a viable solution. The drawback is that it requires extremely accurate channel state information at transmitters for practical usage. When inter-operator interferences is present, asymmetric cellular networks will be likely to appear due to business independency and selfishly compete to access spectrum with no or little network-level coordination. A network designed for more fairness with higher transmission power will have more benefit against the other counterpart. Although asymmetric competition lets operators unfairly utilize spectrum, sharing spectrum with reasonable geographical separation can outperform over static coordination, i.e., traditional spectrum split. Tight cooperation to maximize a common objective can further offer the performance benefit to both involved partners. However, the cooperation gain quickly diminishes as network separation and size increases because self-interference becomes more dominant.

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  • 174.
    Kang, Du Ho
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Interference Coordination for Low-cost Indoor Wireless Systems in Shared Spectrum2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Mobile broadband services have become a big success over the last several years. Innovative, smart handsets have caused explosive traffic growth which has led to a severe capacity shortage. Since the majority of traffic originates from indoor locations or hotspots, significant invest- ment in indoor wireless infrastructure is predicted in order to resolve the capacity problem. While existing public operators mainly focus on high-mobility wide-area services, non-traditional local access providers (LAPs) such as facility owners are more and more interested in high data rate indoor services for their employees or customers. An obstacle is that they do not have access to dedicated spectrum. One proposal is spectrum sharing between LAPs. In shared spectrum, interference management emerges as a key technical challenge, and this becomes more critical as indoor systems become increasingly dense.

    This thesis concentrates on the interference management problem when spectrum is shared between high-density indoor wireless systems. There are two different design directions which require different system architectures. A Wi-Fi or femtocell system works in a fully uncoordinated manner without any inter-cell signaling. This allows high network scalability with cheap devices but leads to poor performance. Alter- natively, advanced interference coordination can be used. It certainly improves the performance; however, it usually requires expensive infras- tructure for real-time information exchange. A key question asked in this thesis is if the interference coordination gives sufficient economic gain to a LAP in terms of a total deployment cost. In order to answer this question, we first develop a conceptual framework to define and compare various levels of coordination. Then, we measure the re- quired number of access points (APs) at a given area capacity demand to estimate the economic gain.

    The coordination decision problem for a LAP is divided into two. Firstly, the LAP needs to choose the right level of coordination within its own network. Secondly, it determines whether or not to cooperate with neighboring LAPs for coordinating interference across the net- works. Regarding the intra-network decision, the comparison ranges from uncoordinated CSMA/CA to ideal interference cancellation. We find the total deployment cost of the uncoordinated CSMA/CA network soars when an area capacity requirement exceeds a certain threshold. The performance gain of the ideal coordination does not pay off the cost of high-speed backhaul because walls effectively suppress interference. Therefore, the most viable approach in a typical indoor environment is using dynamic coordination schemes via existing backhauls, for example Ethernet or xDSL. As for the cooperation decision, our major finding is that non-cooperative spectrum sharing is feasible provided that the transmit power of the APs is properly regulated. Although cooperation with advanced inter-network coordination schemes brings about cost savings, it is not sufficient to overcome practical barriers to a cooperation agreement especially when the capacity demand is high.

     

     

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    Thesis
  • 175.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Han, Sang-Wook
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Competitive Network Power Control between Operators in Shared SpectrumManuscript (preprint) (Other academic)
  • 176.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Li, Zhe
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Luo, Qiuchan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Fathali, Farnaz
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Vizcaino, Alexandre
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Impact of asymmetric transmission power on operator competition in shared spectrum2012In: Communication Technologies Workshop (Swe-CTW), 2012 Swedish, IEEE , 2012, p. 25-29Conference paper (Refereed)
    Abstract [en]

    To maintain affordable access for the rapidly increasing mobile traffic, base station deployment has to be tailored to hot-spot areas and primarily indoors where facility owners, e.g., shopping malls or hotels, mostly provide wireless service. Since such local access providers (LAPs) do not have access to exclusive spectrum, one proposed option is sharing spectrum with other nearby LAPs, e.g. unlicensed or secondary spectrum. Due to limited or no coordination between the LAPs, they selfishly access the spectrum, causing harmful interference to the neighboring networks. Especially by increasing transmission power, one operator may attempt to improve its own throughput at the expense of its neighbors. In this paper, we explore the impact of power asymmetry on competition between LAPs. We model the competition between two networks with different maximum power constraints as a network-wide power control game. By analyzing the pure Nash equilibria, we find that a lower power (LP) network becomes more aggressive to overcome the inter-network interference. Due to the aggressive behavior, sharing spectrum can out-perform fixed spectrum split even for the LP network, provided that the power asymmetry is below a certain limit. On the other hand, a higher power (HP) network is mainly affected by its own 'self-interference' so that it has little incentive to employ complicated inter-operator interference management schemes. In addition, we demonstrate that the power asymmetry limit strongly depends on the inter-network propagation conditions, e.g., inter-building distance or building penetration loss.

  • 177.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Jens, Zander
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    The Validity of Unlicensed Spectrum for Future Local Highcapacity Services2013Conference paper (Refereed)
    Abstract [en]

    Unlicensed spectrum indeed initiates high-data rate wireless services with the combination of the great success of Wi-Fi technology. Interestingly, the local high data rate services are deployed and invested by non-traditional local actors, e.g., facility owners who have local fixed line infrastructure. Motivated by the great success of the Wi-Fi eco-system, there are growing interests from various regulatory initiatives on short-range indoor shared spectrum access to continuously foster new business innovations and local investment by new players. Despite of flexible spectrum access and almost no regulatory management overhead, it is still not so clear that the traditional unlicensed approach can work for future high-capacity services where require extremely denser deployment than today. In this paper, we aim to discuss the validity of the traditional unlicensed approach for the new local operators in an economic aspect. We evaluate the required deployment cost of conventional Wi-Fi system and compare it with a hypothetical cellular-like system with marginal regulatory coordination. We found that the traditional node-level etiquettes in unlicensed band work as system design constraints, leading to too conservative full distributed systems. Although the current unlicensed band approach is the lowest cost solution for relatively low-capacity services, it may not be work at future high-capacity provisioning. Thus, regulations need to be designed to allow more coordinated systems such as cellular-like technologies with certain inter-network regulation.

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    fulltext
  • 178.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Attainable User Throughput by Dense Wi-FiDeployment at 5 GHz2013In: 2013 IEEE 24th International Symposium on Personal Indoor and Mobile Radio Communications (PIMRC), IEEE conference proceedings, 2013, p. 3418-3422Conference paper (Refereed)
    Abstract [en]

    Most of currently deployed Wi-Fi networks use the IEEE 802.11b/g standard and operate in 2.4 GHz ISMband. As mobile traffic demand rapidly increases, significant Wi-Fi deployment in the still very lightly used 5 GHz band is anticipated. In combination with the recent PHY amendments, e.g., 802.11ac, such Wi-Fi in many settings emerges as a strong competitor to small cellular deployment. In this paper, we aim to quantify what total capacity and which data rates per user can be supported by high-density, the state-of-the-art 5 GHz Wi-Fi deployment. Unlike previous studies, we consider the effect of densification by explicitly modeling the different level of interference among access points for office-type scenarios with various internal wall losses. Although abundant spectrum availability at 5 GHz may compensate for system inefficiency caused by carrier sensing and contention, we find that there is a capacity limit. This capacity limit depends on propagation environments and is especially low in 'open' environments or environments with low wall losses. To operate at capacities above this limit, cellular systems with their more advanced interference mitigation techniques are required.

  • 179.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Cooperation and Competition between Wireless Networks in Shared Spectrum2011In: 2011 IEEE 22nd International Symposium On Personal Indoor And Mobile Radio Communications (PIMRC), New York: IEEE , 2011, p. 284-288Conference paper (Refereed)
    Abstract [en]

    As the regulation in wireless communications is moving toward a more flexible and efficient way of managing radio spectrum, it is envisaged that multiple small-sized cellular networks owned by different operators will operate in close vicinity on shared spectrum. This brings a new interference environment where a cell is interfered by not only base stations in own network but also those in other networks. These networks may compete for their own utilities in a selfish manner or cooperate in order to minimize the mutual interference. Since a cooperation between the networks requires a business-wise agreement or extra infrastructure cost, the operators have to identify how much they will benefit from the cooperation. In this paper, we compare the effects of competition and cooperation between the cellular networks. The competition and cooperation are modeled as a transmit power control in downlink. It is observed that the cooperation in an average sense gives better network utility. However, as the network size increases, the cooperation gain diminishes significantly. Furthermore, the marginal separation of network deployments, e.g., indoor deployments in adjacent buildings, can notably shrink the cooperation incentive.

  • 180.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Cost and Feasibility Analysis of Self-deployed Cellular Networks2011In: 2011 IEEE 22nd International Symposium On Personal Indoor And Mobile Radio Communications (PIMRC), New York: IEEE , 2011, p. 248-252Conference paper (Refereed)
    Abstract [en]

    A self-deployed network is considered to be one of cost-efficient deployment solutions by skipping an expensive network planning process. However, it may result in the serious degradation of capacity or the infeasibility of coverage constraint due to the rise of interference although radio adaptation techniques are employed. Therefore, deployment decision makers, e.g., operators, need to identify when and where the self-deployed network is feasible and economical compared with the planned network. For this, we estimate the average network throughput of the self-deployed network subject to a coverage constraint and compare it with the planned network. Three distinct regions of self-deployment are identified where different deployment strategies are required: infeasible, cost-effective, and uneconomical. We evaluate how the regions alter according to different channel environments and make suggestions for economical deployment.

  • 181.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Cost saving of DynamicCoordination using Best-effortBackhaulManuscript (preprint) (Other academic)
  • 182.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Economic Hotspot Deployment Strategy: Denser Wi-Fior Coordinated Pico-cellular?Article in journal (Other academic)
    Abstract [en]

    Rapidly increasing traffic demand has forced indoor operators to deploy more and more Wi-Fi access points (APs). As AP density increases, inter-AP interference rises and may limit the capacity. Alternatively, cellular technologies using centralize dinterference coordination can provide the same capacity with the fewer number of APs at the price of more expensive equipment and installation cost. It is still not obvious at what demand level more sophisticated coordination pays off in terms of total system cost. To make this comparison, we assess the required AP density of three candidate systems for a given average demand: a Wi-Fi network, a conventional pico-cellular network with frequency planning, and an advanced system employing multi-cell joint processing. Numerical results show that dense Wi-Fi is the cheapest solution at a relatively low demand level. However, the AP density grows quickly at a critical demand level regardless of propagation conditions. Beyond this “Wi-Fi network limit”, the conventional pico-cellular network works and is cheaper than the joint processing in obstructed environments, e.g., furnished offices with walls. In line of sight condition such as stadiums, the joint processing becomes the most viable solution. The drawback is that extremely accurate channel state information at transmitters is needed.

  • 183.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Economic Spectrum Reuse between Inbuilding Wireless Access NetworksManuscript (preprint) (Other academic)
  • 184.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    High capacity indoor and hotspot wireless systems in shared spectrum: A techno-economic analysis2013In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 51, no 12, p. 102-109Article in journal (Refereed)
    Abstract [en]

    Predictions for wireless and mobile Internet access suggest an exponential traffic increase, particularly in in-building environments. Non-traditional actors such as facility owners have a growing interest in deploying and operating their own indoor networks to fulfill the capacity demand. Such local operators will need spectrum sharing with neighboring networks because they are not likely to have their own dedicated spectrum. Management of internetwork interference then becomes a key issue for high capacity provision. Tight operator-wise cooperation provides superior performance, but at the expense of high infrastructure cost and business-related impairments. Limited coordination, on the other hand, causes harmful interference between operators, which in turn will require even denser networks. In this article, we propose a techno-economic analysis framework for investigating and comparing indoor operator strategies. We refine a traditional network cost model by introducing new inter-operator cost factors. Then we present a numerical example to demonstrate how the proposed framework can help us to compare different operator strategies. Finally, we suggest areas for future research.

  • 185.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Is Multicell Interference Coordination Worthwhile in Indoor Wireless Broadband Systems?2012In: 2012 IEEE Global Communications Conference (GLOBECOM), IEEE , 2012, p. 4255-4260Conference paper (Refereed)
    Abstract [en]

    The rapid growth in demand for mobile and nomadic wireless access forces the use of more and more base stations (BSs). In such dense networks, various techniques for multicell interference coordination have been investigated. However, whether or not the interference coordination provides cost benefit compared with a loosely coordinated system is not obvious because the tight coordination at PHY-layer is likely to need an expensive high-speed backbone infrastructure. In this paper, we assess the worthiness of the tight interference coordination, referred to as coordination gain, in various indoor environments. We compare a hypothetical interference-free system as an upper bound with a simple interference-limited system opportunistically avoiding interference. The range of possible coordination gain is examined for various wall losses, path loss exponents, building shapes, and deployment density. Results show that substantial gain can be achieved in dense deployment at open areas with low path loss exponent, e.g., lightly furnished offices partitioned with soft walls. Nevertheless, the coordination gain significantly drops in the presence of marginal wall loss regardless of the other environmental factors.

  • 186.
    Kang, Du Ho
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Operator competition with asymmetric strategies in shared spectrum2012In: 2012 IEEE Wireless Communications and Networking Conference, WCNC, IEEE Communications Society, 2012, p. 3183-3187Conference paper (Refereed)
    Abstract [en]

    As the regulation in wireless communications is moving toward a more flexible and efficient way of managing radio spectrum, it is envisaged that multiple small-sized cellular networks owned by different operators, e.g., facility owners or local operators, will operate in close vicinity on shared spectrum. In this environment, the networks may compete for their own utilities in a selfish manner with giving harmful internetwork interference to competitors. In practice, it is not so unusual that each operator has different fairness criteria or quality of service (QoS) strategies by employing distinct objective functions from competitors. Particularly, we in this paper study power control competition between two networks with the sum of rates (SR) and the minimum rate (MR) as their objective functions, respectively. By exploring Nash equilibria, we identify that the MR network benefits from the objective asymmetry thanks to the adaptability of its competitor, i.e., no constraint in the SR objective. On the other hand, the SR network takes disadvantage due to the fairness requirement reflected in the MR objective of its competitor. However, such asymmetry effects in competition becomes negligible with marginal network separation, e.g., indoor deployment in adjacent buildings. Additionally, we identify cooperation potential with the proper choice of a common objective function although the asymmetric objectives are difficult to be aligned.

  • 187.
    Karlsson, Alexander
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Al-Saadeh, Osama
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Gusarov, Anton
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Challa, Renuka Venkata Ramani
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Tombaz, S.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Energy-efficient 5G deployment in rural areas2016In: 12th IEEE International Conference on Wireless and Mobile Computing, Networking and Communications, WiMob 2016, IEEE Computer Society, 2016, article id 7763258Conference paper (Refereed)
    Abstract [en]

    Energy efficiency is of profound importance for prospective 5G wireless networks, especially in sparsely populated rural areas where broadband mobile services should be provided at a reasonable cost. In this paper the impact of beamforming (BF) and cell discontinuous transmission (cell DTX) technologies on the average area power consumption is studied. The required density of base stations for a 5G cellular system in a rural environment is also investigated. For this purpose, we propose a simple rural area model that captures a non-uniform distribution of users and employ the generalized Lloyd algorithm to determine the deployment of base stations. We assume a 5G system operating in mmWave band centered at 28 GHz with the bandwidth of 100 MHz, compared with existing LTE networks at 0.8 GHz with a 20 MHz bandwidth. Simulation results show that for the 5G network the density of base stations needed to provide 50 Mbps for 95% of users at the busy hour will be reduced by 8-9 times with the implementation of BF. It is also observed that BF has a greater effect on the energy saving of 5G networks in rural areas in comparison to the cell DTX.

  • 188.
    Karlsson, Carl
    et al.
    Center for RF Measurement Technology, University of Gävle, Gävle, Sweden.
    Ängskog, Per
    Center for RF Measurement Technology, University of Gävle, Gävle, Sweden.
    Ferrer Coll, Javier
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Chilo, Jose
    Center for RF Measurement Technology, University of Gävle, Gävle, Sweden.
    Stenumgaard, Peter
    Center for RF Measurement Technology, University of Gävle, Gävle, Sweden.
    Outdoor electromagnetic interference measurements in industrial environments2009In: AMTA 2009, 2009Conference paper (Refereed)
    Abstract [en]

     The performance of wireless applications in outdoor industrial environments is degraded by the effect of unknown interferences. Therefore, characterization of these environments has to be done. Measurements have been performed to determine electromagnetic interference in three outdoor industrial environments: steel mill, freight train marshalling yard and paper plant. In this paper it is shown how the measurements of the Amplitude Probability Distribution (APD) can be combined with conventional electric field measurements for such characterization in order to determine the interference impact on digital wireless systems.

  • 189.
    Khamit, Saltanat
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Towards Open Mobile Broadband Market with Energy-Efficient Deployment2011In: Proceedings of the 10th Scandinavian Workshop on Wireless Ad-hoc Networks (ADHOC'11): Wireless Architectures for the Internet Things, 2011Conference paper (Other academic)
    Abstract [en]

    A growing demand for mobile broadband services will, sooner or later, cause a service provider to face problems in terms of network capacity. The pressurizing situation is more noticeable in a highly competitive environment. It is challenging for a new service provider to maximize the profitability while, at the same time, maintain high quality services. For virtually any network deployment strategy, the service provider will need to look at ways to reduce capital expenses (CAPEX) to decrease the cost per service. A better energy utilization is believed to have the potential to lower the network operation expenses (OPEX) and to balance network coverage versus user traffic. A cost structure and energy-efficiency in the mobile broadband network is crucial for success. In this paper, we consider a competition between incumbent and entrant providers, where the entrant chooses a suitable deployment strategy at the market entry. Both providers are profit- maximizers. We propose two competitive deployment strategies (“Cost Leadership” and “Differential Pricing” strategy) with an energy consumption constraint. The system performance is evaluated in terms of network size (market share), transmitted power, antenna height and user preference. The simplistic model used in this paper gives a clear understanding of investment needed for the expected coverage and capacity of the network. A provider who chooses to deploy a radio access technology smartly, focusing primarily on business strategy and cost efficiency, would benefit greatly.

  • 190. Kimura, K.
    et al.
    Yamamoto, Koji
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Murata, H.
    Yoshida, S.
    End-to-end throughput aware adaptive channel and route selection for enhancing system throughput in multi-hop radio networks2008Conference paper (Refereed)
    Abstract [en]

    A distributed power, channel, and route selection scheme for multi-hop radio networks is proposed by extending Multichannel Asynchronous Distributed Pricing (MADP) algorithm, which is a power and channel selection scheme for single-hop radio networks. MADP algorithm achieves suboptimal system throughput in single-hop radio networks, however, since MADP algorithm allocates more resources to links with good quality, there may be a large difference in throughput among communication links. Particularly in multi-hop radio networks, MADP algorithm might not necessarily achieve high system throughput because the link with the lowest throughput limits the end-to-end throughput of a given multi-hop route. In order to achieve high system throughput in multi-hop radio networks, a modification of MADP algorithm named End-to-end Throughput Aware MADP (ETA-MADP) algorithm is proposed. It is proved that all links in a given multi-hop route have the same throughput through the use of ETA-MADP algorithm. Simulation results reveal that the introduction of the proposed algorithm achieves high spectral efficiency in multi-hop radio networks even with lower transmit power compared to that in single-hop radio networks.

  • 191. Kumar, Pavan
    et al.
    Lungaro, Pietro
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Nandakumar, Vikrant
    Segall, Zary
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    A novel experimental framework to investigate context-aware solutions for opportunistic M2M content delivery2011Conference paper (Refereed)
    Download full text (pdf)
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  • 192.
    Laya, Andres
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Bratu, Vlad Ioan
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Markendahl, Jan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Who Is Investing in Machine-to-Machine Communications?2013In: 24th European Regional ITS Conference, Florence 2013, 2013Conference paper (Refereed)
    Abstract [en]

    Machine-to-Machine (M2M) communications refers to the automate exchange of information between devices for control and monitoring applications. This type of communication is not new since automated systems have been present for more than three decades. However, miniaturization of device’s size, reduction of production costs and drop in communication fees (altogether with the massive adoption of real-time access of information in current society) are expanding the set of applications and solutions currently under consideration. The real complexity relies on the fact that M2M is not only an add-on communication solution, like the case of traditional human-centric broadband communications. M2M usually entails a change in the core business of an industry, since the relationship with external partners and the internal tasks can be radically modified

    In this paper, we anaylise the players involved in M2M communications and how they position themselves in a market which requires them to adjust their traditional business approach. The main question addressed in this work refers to “which players are investing in M2M, which is their view and how could their approach affect the current ICT sector?” We highlight the dominance and relationship between different actors and also look at barriers that prevent investments, regulations in the area and standardization efforts.

    Using data from interviews, use case analysis, and expert workshops we place our analysis in a real-market context. It can be concluded that there is a consensus about the potential benefits of services based on M2M communications and key succes factors are partnerships among different actors, re-thinking of roles, e.g., transition to a service provider and defining the right type of value added service

  • 193.
    Laya, Andres
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Ghanbari, Amirhossein
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Markendahl, Jan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Tele-economics in MTC: what numbers would not show2015In: EAI Endorsed Transactions on Internet of Things, ISSN 2414-1399, Vol. 1, no 1Article in journal (Refereed)
    Abstract [en]

    This paper elaborates on the relevance of Tele-Economic research to understand the effect that Machine-Type Commu- nications (MTC) has on different markets and also the market forces affecting the adoption of services based on MTC. The paper is presented in a tutorial form, offering concept and definitions of economic terms that are gaining relevance in the technical community in the MTC context. The concept of services is further analysed in as a change in the tele- communication industry mind-set in order to tap into the economic value of MTC in the realization of the Internet-of- Things. Finally, insights are presented looking forward into the relevance of Tele-Economic research for 5G.

    Download full text (pdf)
    fulltext
  • 194.
    Laya, Andrés
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Markendahl, Jan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    The M2M promise, what could make it happen?2013In: 2013 IEEE 14th International Symposium on a World of Wireless, Mobile and Multimedia Networks, WoWMoM 2013, IEEE , 2013, p. 6583489-Conference paper (Refereed)
    Abstract [en]

    Machine-to-Machine (M2M) communications is a topic of great importance that maintains an ongoing interest in the academic community and in countless industries and services. Technological advances allow the successful deployment of particular solutions but many potential applications still face limitations that prevent them from happening. This paper compares data collected from five implementation cases in order to analyze key issues related to their value proposition and the challenges that currently limit the adoption of M2M communications.

  • 195. Lindmark, B.
    et al.
    Lundgren, S.
    Beckman, Claes
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Dual polarized aperture coupled patch multibeam antenna1998In: IEEE Antennas and Propagation Society International Symposium. 1998 Digest. Antennas: Gateways to the Global Network. Held in conjunction with: USNC/URSI National Radio Science Meeting (Cat. No.98CH36, 1998, Vol. 1, p. 328-331 vol.1Conference paper (Refereed)
    Abstract [en]

    We present a dual polarised multibeam antenna intended for use in a PCS (1850-1990 MHz) base station. Although the coupling between adjacent antenna columns is quite high the radiation patterns and cross-polar characteristics are satisfactory. The port-to-port isolation between polarisations is also limited by inter-array coupling but still exceeds 22 dB in the frequency band.

  • 196.
    Lindström, Magnus
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture, Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Lungaro, Pietro
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture, Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Resource Delegation and Rewards to Stimulate Forwarding in Multihip Cellular Networks2005In: VTC 2005-Spring: 2005 IEEE 61st Vehicular Technology Conference, Proceedings, IEEE , 2005, no 4, p. 2152-2156Conference paper (Refereed)
    Abstract [en]

    Multihop cellular networks that base the forwarding process on user terminals are challenged by a lack of forwarding incentive. In this paper 1, we present the novel concept of Resource Delegation which, applied in combination with pricing based rewards, guarantees both the separation of resources between originating transmitters and relays and the economic compensation of the energy investments of the relays. The results show that this strategy leads to the definition of a broad region of prices in which multihopping solutions can achieve the following advantages over classical single-hop architectures: operator's revenues and provided datarates increase significantly, the users' appreciation of the service is enhanced, and the average interference level of the network is lowered.

  • 197. Liu, Lingjia
    et al.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zhang, Jianzhong(Charlie)
    Energy-Efficient Scheduling for Downlink Multi-User MIMO2012In: IEEE International Conference on Communications (ICC) 2012, IEEE conference proceedings, 2012, p. 4390-4394Conference paper (Refereed)
    Abstract [en]

    Multi-user MIMO is the enabling technology forLTE-Advanced systems to meet IMT-Advanced targets. The gainof multi-user MIMO is achieved partially through advanced usergrouping,user-scheduling, and precoding. Traditionally, multiuserMIMO scheduling focuses solely on spectral-efficiency [1].That is, the scheduler will strike to balance the cell-edge userspectral-efficiency as well as the cell-average spectral-efficiency.Similar to spectral-efficiency, energy-efficiency is becoming increasinglyimportant for wireless communications. The energyefficiency is measured by a classical measure, “throughput perJoule”, while both RF transmit power and device electronic circuitpower consumptions are considered. In this paper, an energyefficientproportional-fair scheduling is proposed for downlinkmulti-user MIMO systems. To specific, the scheduling algorithmis proposed to balance cell-edge energy-efficiency and the cellaverageenergy-efficiency. The energy-efficient proportional-fairmetric is defined and the optimal power allocation maximizingthe performance measure is identified. System level evaluationsuggests that multi-user MIMO could improve the energyefficiencyof a wireless communication system significantly.

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    fulltext
  • 198.
    Lungaro, Pietro
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    "Word-of-Mouth" in Radio Access Markets2005Conference paper (Refereed)
    Abstract [en]

    Opening up interoperability between wide and local area networks seems to be a very promising solution for delivering improved user experience while reducing overall service costs. In a scenario, where a single operator owns different types of networks, QoS provision can be achieved by introducing complex multi-system resource management. On the contrary, if local area networks are deployed by different entities, due to the lack of both coordination and centralized RRM management, the experienced QoS may drastically fluctuate, ranging from SLAs in wide area, to only ''best effort" expectations in local area networks.

    In order for "nomadic" terminal agents to perform "informed" access selection decisions, we propose the adoption of "Word-of-Mouth" (WoM), a novel scheme for sharing, in a peer-to-peer fashion, information about the service quality experienced with different networks. The performances of our proposed WoM scheme have been evaluated for a file pre-fetching service, considering information characterized by various degrees of time criticality, when different RRM strategies are implemented in the local area networks. The results show that if a critical mass of terminal agents exchange experienced QoS information, the overall network selection decision is improved: terminal agents can estimate, on beforehand, which type of performances to expect with different candidate networks, and avoid to select those not satisfying service requirements. This, in turn brings two main positive effects: on one hand, user perceived performance is improved, and, on the other hand, the adoption of RRM strategies providing some degree QoS is incentivated.

  • 199.
    Lungaro, Pietro
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Segall, Zary
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Application-centric Content Delivery Schemes for Future Wireless Networks2011In: 2011 IEEE 22nd International Symposium On Personal Indoor And Mobile Radio Communications (PIMRC), New York: IEEE , 2011, p. 2128-2132Conference paper (Refereed)
    Abstract [en]

    The apps paradigm is rapidly changing the way in which content is transferred and consumed in mobile networks. Currently, the traffic loads generated by apps are mostly provided as Over-The-Top (OTT) services, essentially transparent to the cellular network operators, while some of the content is delivered and updated in user terminals through "background transmissions", without user intervention. With increasing traffic volumes, associated to richer content and more advanced devices, the apps paradigm might create severe system inefficiencies. In this paper we explore a number of apps based content delivery methods and investigate their performances on multiple relevant dimensions,such as: terminal energy consumption, time for accessing in-apps content and their impact on the user experience associated with other mobile data services. The proposed methods include opportunistic content pre-fetching and are characterized by different degrees of context-awareness. One approach considers only context information at the individual user terminals, while another one includes network context information and assumes that content distribution coordination is performed by the network operators. The results show that when one is increasing the numbers of apps, whose content needs to be simultaneously maintained updated, only the operator-driven approach can be feasible, mainly from an energetic perspective. However, for a small number of maintained apps, pre-fetching schemes are superior to standard "on-demand" content delivery solutions, suggesting that pre-fetching should be limited only to the subset of terminal apps with higher user access probabilities.

  • 200.
    Lungaro, Pietro
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Segall, Zary
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    ActiveCast - a network and user aware mobile content delivery system2010In: Ubiquitous and Future Networks (ICUFN), 2010 Second International Conference on, IEEE , 2010, p. 309-313Conference paper (Refereed)
    Abstract [en]

    Most of the currently deployed networks are typically dimensioned considering the "peak hour" traffic demand. Opportunistically utilizing these "excess" resources might be an effective way for improving utilization and lowering the "production" costs. This paper is proposing and evaluating a novel concept, called ActiveCast, and the corresponding architecture for a network and user behavior aware mobile content delivery system. When considering real traffic measurements in urban scenarios we showed that the concept improves the resource utilization and allows serving significantly more users in a pre-existing network. Even with moderate amounts of reliable context information, ActiveCast have been shown to drastically improving both user quality of experience perception and network efficiency, as compared to conventional on-demand content delivery schemes.

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